One of the great challenges in this world, is knowing enough about a subject to think you're right...but not enough about the subject, to know that you're wrong...
@@BritishBeachcomber That-s typical among Scientism adepts. You can find a lot of PhD holders who are dishonest idiots My favorite example is a PhD in MATHEMATICS who said 10^12 > 10^23 just to slander the target of his hatred
An even greater challenge is knowing when you're being hoodwinked by social manipulators who are actively molesting you and insulting your intelligence by directly appealing to known preconceived notions and preferred (habitually maintained) bias, while making you believe they're "clarifying" something for your intellectual benefit. See my other comment for more details
I for one appreciate that he actually got the "lift" concept correct, aside from the speed of the air concept. But explaining lift is as simple as saying that air *does* push up on the wing because there is a greater concentration of air molecules below than above it on the other side, and the forces aren't equal. AKA "static differential". The wing, being between these two pressure zones, will want to move in the direction of least pressure... generally "up" in a plane. Bernoulli's principle is virtually a separate "issue" and is only the *cause of the differential* pressure. Just look at the smoke trail clip. Notice how the smoke is spread out above, and highly concentrated below. Not sure why this is such a difficult concept for people to grasp. No need to over complicate it until you need to do the actual math.
Lift is cause by action and reaction - molecules been deflected downwards, which cases lift. The pressure differential is a reaction to the deflection of molecules, not the cause if lift. R
@@RalphEllisCorrect. F=Ma. The amount of lift is equal to the mass of the air and how much it is accelerated. Maybe not equal but that’s essentially it.
I went to engineering school with guys like NDT - so eager to teach and or sound smart that they have to sound authoritative in everything, regardless of how little understanding they have of whatever topic they're wandering through at the moment.
So did I. I was shocked at how many people knew so little about what they wanted and tried to teach. I'm now a pilot and was tutoring someone on instrument flying. Another pilot who didn't even have an instrument rating kept interrupting to also teach the student. He NEEDED to be the center of attention and seen as smart. It was a pathology he didn't see in himself. After he finally left the room I told the student to completely disregard what he interjected. And since then I would never have him near the controls of any aircraft I was in.
@@timn4481 I didn't intend to claim he doesn't know much, he's obviously very intelligent, and so we're my engineering peers, but he and they had this attitude of, "I'm good at a difficult subject, therefore I must be smart about all other subjects." You can tell he's thinking about some of this stuff for the first time, and assuming that as he solves the issue(s) in real time while discussing them he must be coming up with the same solution that others had already figured out over the years. In this case: runway configurations at airports.
There are MANY aerodynamics engineers that get this wrong because it IS what we were taught in college back in the 80s and later years. It wasn't until later that some professors put their videos on youtube to correct the mistake. So that he got it wrong isn't surprising nor does it mean he doesn't know what he is talking about with respect to other subjects just as I posted.
@@diegom8 >> There are MANY aerodynamics engineers that get this wrong This is maybe the most basic thing in all of aerodynamics. If an aero engineer today gets this wrong, they have been in a coma for 40 years. This is roughly equivalent to a doctor using blood-letting.
I'm gonna correct one thing - he wants us to think he knows it all. I wish he'd stick to topics he really knows, but he likes the sound of his own voice, so I know he won't stop.
I'd blame the current need of "marketization of the self" nowadays more than him "liking the sound of his own voice". If you want to stay relevant as a 'product', you need to keep pushing out content, so ppl like deGrasse Tyson push themselves out of their zones of actual knowledge. Same goes for many of the science communicators on SoMe. Another example is Sabine Hossenfelder, and I'm sure you can find many more that have started within their fields of expertise, but then started reaching outside of that and start getting things wrong.
@@Jarlerus It wouldn't be surprising for mistakes to crop into anyone's work, particularly after making a lot of videos, but are there examples of videos from Hossenfelder where the entire video is wrong or misleading?
@@oliverbatt3559 Videos with outdated, limited, and narrow perspectives. Often around more politicized topics. Still, it shows a lack of actual expertise in subjects. Just like the Tyson video referenced here; The explanation is simplified, parts of it (f.ex. how Bernoulli's is explained) might be correct, but the whole lacks a lot.
@@HopDavid If you can do a better job, you should give it a go. We need more people advocating science for people too lazy to put in the work themselves.
His take on helicopters falling like a brick in the event of an engine failure was disappointing. Just a quick Google search would answer it. But I have a feeling he doesn’t feel the need to Google much.
Years ago before he was exposed as a hack, I listened to him on star talk explaining that elon musk could not accomplish the things he is doing easily today, and that the privatization of space would never happen, and this should always be the governments job. Then went on to explain incorrectly fundamental aspects of rocketry
As a pilot, listening to Tyson's explanation of lift was like listening to fingernails on a blackboard... Also, anytime anyone says that natural phenomenon "wants" to do something, it's time to change the channel.
Yeah, that was the first obvious error. After all, once the parcel of air has been split by the leading edge of the wing, don't the two halves want to get as far apart as possible, like any recently split couple?
@@MStoica I disagree. Speaking and writing as if physical phenomena (such as air molecules) have conscious volition _is not_ helpful or instructive to subject-matter novices. Better is to explain in a manner consistent with the know science, yet slowly and carefully and within the audience’s capacity to comprehend. Often, the false attribution of conscious volition is an indication that the speaker himself doesn’t fully understand the subject matter.
@@MStoica If he's purposely spreading falsehoods to build his follower count, that's even worse than his own not understanding the subject in the first place.
Magnar, well done! I too watched the Neil deGrasse Tyson video (due, in part, to his celebrity status), only to find myself muttering “no, no, no ….”. Thanks for putting together such a well researched, technically correct, exposé of three common misconceptions in aeronautics.
From the outside, it appears that Mr Tyson's self worth is wrapped around being the smartest person in any room he enters. And it doesn't seem like that meshes well with the final quote in this video.
Lao Tzu - The wise man is one who, knows, what he does not know. And its corollary - Stay in your lane. In short, no one has a good grasp of everything. When one thinks they do, that's precisely when they get into trouble.
He’s successful because a frustratingly large ratio of ppl respect charisma more than intelligence. Say the thing dramatically and commandingly, and ppl will think there’s substance behind your confidence-but that’s only because most ppl aren’t bold enough to lie that well.
I love it when you can ‘see’ the low pressure envelope above a wing when planes are close to landing in wet humid conditions. That cloud above the wing.... now you see me, now you don’t. The same conditions also show the powerful vortices coming from the outboard tips of the trailing edge flaps. When lift and wake air turbulence become visible.
A perfectly flat panel, with no curvature, generates lift. Small wooden children's toy airplanes use flat sheets for wings, and they fly just fine. Properly curved airfoils can increase lift efficiency. Cantilevered wing tips can help with reducing vortices, thereby reducing stall speed. There are optimal designs for these also. Long thin wings are more efficient than short fat wings at generating lift, but long thin wings are more susceptible to turbulence. Each blade in a jet engine is a type of wing.
I used to like Neil’s science descriptions. Then I saw him give a keynote live at a technical conference in San Francisco. I forgot what topic he was talking about, but the number and level of bombastic arguments and assumptions was counter to what I learned from my scientific mentors. (Three of them are notable enough to have Wikipedia articles.) But upon watching this (and I’m only at 11:30 ), my level of Picard facepalming has reached a new level. How does he get these cowpies past his fact-checking team?
Does anybody ask the question WHY? I bet he never did actual calculations on aerodynamics all by himself. Sure he CAN, but this video only leaves the impression, Tyson did not go into detail, here. Mind you, there is a whole lot more to know about wings and planes. The first supersonic planes went down like a brick, trying to kill the pilot. It took a while before it was clear what caused such problems. And that is just one example. See? It is even difficult explaining how wings work, before you know it, you are marketing an out dated theory. And these weird tit for tat comments here, well, it doesn't make me happy, either.
@@christopheryellman533he made his own mistakes too. There was a whole segment in the original Cosmos about the burning of the Library of Alexandria and the middle ages which is entirely misinformation for example. Everyone has their blindspots.
@@AdamBrusselback A friend of mine was an undergraduate at Cornell, and one of his classmates worked in Sagan's lab. He said when he went in there to visit him, there were clouds of smoke from the good weed.
I respect Dr. Tyson, but it surprised me when he stated that a helicopter cannot glide if its only engine stops. I fly single-engine airplanes and helicopters, and I'd rather be in the latter when the engine quits.
Interesting. Do you chalk that up yo your autorotation skills, or are you saying autorotation has better odds than gliding, period? If the latter, care to elaborate please?
@@--SPQR--i guess autorotation allows you to land where you choose in a small area; a plane still needs a nice flat field or similar. though bush planes can land pretty easily in a small space
I heard the bit about the air going a longer distance and wanting to "catch up" 50 years ago when I was 12. Seemed wrong to me even back then. Thanks for finally setting the record straight.
@@davetime5234 I'm not trying to dispute Bernoulli; just sayin' that it's Newton that *entirely* accounts for LIFT. "Equal and opposite" is not "optional"!
Thanks for confirming what I have known as a pilot for years. Interesting to note, I still, on occasion have to correct certified flight instructors during bi-annual reviews, that bernoulli alone is not sufficient. In fact, there are still manuals out there that still teach it incorrectly.
As noted by others - if “Equal transit time” were correct then inverted flight would be impossible, as would flat high-speed wings that have no curvature. Holding angled cardboard out a car window forces it upward.
That's a misconception. Inverted flight wouldn't work if equal transit time were the ONLY way to create lift. AoA can create lift AND the airfoil shape and resulting different velocities ALSO create lift. Claiming that Bernoulli lift makes inverted flight impossible is like saying that the existence of pizza makes hamburgers impossible. BOTH exist. Then you have explanations based on air flowing downward long after the wing has passed by. Such as mentioned early in this video. But that explanation violates the law of causation - the air going down later can't push the wing up earlier. Cause always comes BEFORE effect. The cause can't come AFTER the effect. The air flowing downward AFTER it has left the wing is a result, an effect, of lift - it can't be the cause.
@@thomasward4505 Put most simply, wings generate lift via momentum transfer. The airfoil redirects the flow of air downward (provided there is AoA or camber) and this results in a reaction force on the wing that both produces lift and drag. Conventional wings will produce lift inverted provided there is sufficient angle of attack. Symmetric airfoils will also generate lift in both orientations, but require that there is always some angle of attack or no lift will be generated as the airflow will be unperturbed. Conventional wings like those on an airliner are designed to generate lift even in the absence of AoA so that the plane can fly level during cruise to reduce drag. There is a lot more to it, such as the wing being “high performance” capable of generating large quantities of lift even at relatively slow speeds. This also comes with proportional amounts of drag (which is a lot) which is one reason jets have such large powerful turbofans.
@@thomasward4505 And fwiw flying inverted will generally require more power since the wing is not optimized for negative angles of attack unless it’s specifically designed for it. But most of the time inverted flight is impossible due to the design of the fuel and lubrication systems since they are gravity fed. The fluids will collect on the opposite side and expose the sump to air. I believe in fighter jets there are reserve lubrication and fuel tanks designed specifically for negative g’s that allow for brief periods of flight inverted. Also the famous “vomit comet” used for low-g training gets around this by having specific minimum requirements for the quantity of fuel onboard so that the pickups remain submerged even in near zero g.
A simple experiment I was shown in the 1960s, long before I gained my humble private pilots license, involved 2 pieces of paper. Take a sheet of, let’s say, copy paper and hold it horizontally, like a mouth organ, but just under your bottom lip. If you blow across that paper, even quite gently, the sagging sheet will lift to be horizontal in both directions, left to right and front to back. A more dramatic experiment is to hold 2 sheets of paper vertically, close together and up against your lips. When you blow between them, fairly hard, you will be rewarded with the noisy report of the 2 sheets flapping wildly against each other. These are but 2 examples of Daniel Bernoulli’s principle at work. Oh. another example, I experience it every morning, is the way a shower curtain is drawn inwards by the water rushing past it, same principle. Smart man that Dutch born Swiss mathematician/physicist! The other factor keeping aircraft airborne is that the wings push the air down, via the angle of attack, not unlike a water skier’s skis. This is well illustrated by the slight drop in altitude noticed when an aircraft moves out of ground effect immediately after it leaves the end of the flight deck of an aircraft carrier. This is more pronounced with lower powered planes.
My father was a pilot and owned a cessna 150. You definitely learn about ground effect when landing! It's said that it has an effect within 1/2 of the wingspan from the ground. One trick for short field over obstacle grass runway takeoffs he would use was to wind up the engine, release the brakes, lift off the ground early long before normal rotation speed was reached, by using ground effect, then level our a foot or two above the runway, thus using ground effect, to remove the rolling resistance of the wheels to "run like hell" gaining momentum until he could "pop" it up just over the trees then level off again to gain speed back to establish normal climb rate. Bush pilot's trick. Flying is about energy management. I know of a "gotta go!" fatal plane crash of a plane from a short slush covered runway that failed to clear an obstacle because this wasn't followed. The slush slowed the acceleration and they knew this would be a factor. It's usually against policy but as soon as you are commited to the takeoff in this situation, and the plane will fly in ground effect lift up a couple feet, retract the gear to reduce drag and "run like hell!" Gradually gaining a few more feet to prevent a tail strike if needed get all the speed you can, and trade energy for required altitude, then unload the airplane to gain back climbing speed. Instead, they lied to the airplane, stayed on the runway, trying to get to normal rotation speed, failed, and then just kept hauling back on the stick, willing it to fly, gained a mabey 50 ft and stalled. "You can lie to your friends and family, but if you lie to your airplane, it will kill you!"
blowing on a sheet of paper has nothing to do with a airplane wing , airplanes fly because of the air pressure difference between the top and bottom of the wing and that's it , exactly how a vacuum cleaner works , shape , size, thickness, delta all has to do with application ,
@@cardboardboxification Starve the lizards! I have provided everyone, even you, with some easy experiments that beautifully demonstrate the theory of pressure differential and is EXACTLY what I was refering to, because the air above the sheet is travelling at a greater speed than that below, albiet at zero speed, the air pressure below the paper sheet is higher than that above the “wing” thereby lifting it skyward. Anyway that’s how it was explained in the 1960’s by a senior TAA pilot,on Channel 9 TV. He also demonstrated the blowing between 2 sheets routine. A retired Cathey Pacific flight engineer cousin of mine mentioned the shower curtain phenomenon to me last year. How else would these paper sheets react the way I’ve explained, perhaps you should try it it sometime?
It's worth noting that whilst most flaps on modern aircraft typically do two things to increase lift - extend the wing surface area by travelling rearwards somewhat to temporarily make a bigger wing, and tilting downwards to temporarily increase the camber of the wing - not all flaps do this, some types work a bit differently. There are quite a few types of flaps, including plain flaps, slotted flaps, fowler flaps and split flaps and they all have somewhat different features and work in slightly different ways, but the interesting one where discussions about what produces lift are concerned, is split flaps. Two very famous aircraft which we all know pretty well - the Supermarine Spitfire and the Douglas DC-3 - have split flaps, whereby the bottom half of the rear wing area lowers, but the wing surface above that section does not move at all, so this arrangement neither increases the wing surface area, nor does it alter the overall camber of the wing, yet it still produces lift; it does that largely by deflecting air downwards, which in turn forces the wing upwards, i.e. it is taking advantage of the effect of Newton's Third Law of Motion - to every action, there is an equal and opposite reaction - so, no Bernoulli Effect required here at all. Split flaps create a lot of drag however, thus they are typically more helpful for landing than for taking off, where you basically want a lot of drag to slow your descent speed. They are not quite so great for take-off, because they act on the rear of the wing, so they significantly increase pitch down too. All this is why you don't really tend to see split flaps much these days. Nevertheless, despite there being more efficient flap types than those found on the DC-3 and the Spitfire, the existence of split flaps is enough proof that there is more than just the Bernoulli Effect involved in creating the effects necessary for an aeroplane to fly around. To be fair to Neil DeGrasse Tyson, the gist of what he is saying is more or less true and probably just about good enough for people who don't really need to know everything about a subject. Really this is his oeuvre, in making layman's terms simplified explanations of stuff to people with no knowledge of a subject whatsoever. He could probably do with sorting out his terminology a bit however, for example when he refers to elevators as rear wing flaps, whilst this is kind of what they are in terms of function, it adds to the confusion a bit to use these simplified terms. It's not too hard for people to grasp things in using the correct terminology, so he should really endeavour to do that. Being someone who trains people on aircraft, I do find myself on occasion having to explain the various bits of an aeroplane when walking around them and pointing to those parts, so whilst I can appreciate that you don't want to overload people with information, giving a proper explanation and using the correct names for things is never a bad idea; people will 'get it' if you tell them things properly.
On another explainer, Tyson said that airplanes taxi in the air above the airport, and not on the ground. Chuck Nice was visibly disturbed by Tyson's explanation, because even Chuck knew that aircraft taxi on the ground….on taxi ways.
High time you all start paying real taxi's. Then everybody can go to excellent public schools and that will avoid having so many people losing contact with mother earth. Educate like everybody, like it was like centuries like ago. Like. Duh.
@@marquisdelafayette1929 Yes, and he uses exactly the WRONG word for that. Besides, that word taxi is ridiculous, anyway. Who invented that, deserves spanking on his taxi area's.
It's probably reaching to apply that to everyone. They only used 45 people in the study, and they were all ivy league undergrads. I think Tyson has an idea that "smart" means he can't be wrong, and that anything that sounds reasonable to him must be right. Also that anything that confirms what he already assumes or believes must be right, and this gets extended to subjects that aren't science-related. You never really become smart without sufficient self-doubt.
Several years ago I was looking through a graduate level aeronautics textbook where the author was discussing lift via Bernoulli & upper/lower path length. He concluded that a Cessna 182 would have to accelerate to over 400MPH to lift its own weight if this were the mechanism that enabled a wing to generate lift. It is amazing that this myth is still being taught by the FAA and was a multiple choice answer on the airman 3rd class written test.
When taking those silly FAA written exams, I studied normally to learn the stuff, sure, but then a couple days before the test just start going through the list of all the FAA questions that they publish (do they still?) that has every question and every answer and memorizing--and there was always at least one question where the book warns "the FAA wants you to answer B even though that's wrong". Sure makes it go quicker when you recognize the question and don't have to read it and can just pick B or D or whatever without any work. I finished the instrument 3 hour test in about 25 minutes. Proctor asked "are you giving up?" "No, I'm done". 98/100. Dunno what I missed and that still haunts me.
lift is pressure differential between the top and bottom of wing and that is it , nothing more... shape, size ,flat bottom , fully symmetrical , straight , delta ... all has to do with application , weight , speed
The problem is that as kids we were all taught about this cool effect, and it stuck with us. What we seemed to forget about is sticking our hand out of the car window at 60 mph. AoA trumps airfoil effects. A brick can fly with enough thrust and AoA.
This was one of the first lessons I had for my private pilot certificate. I remember my flight instructor explaining it like Neil explained it but my ground instructor explained the way you did. I eventually convinced my flight instructor to talk to the ground instructor so they would be on the same page. Fun times! Thanks for the video! 🙂
Neil DeGrasse Tyson, and most others, also forget that you can build a plane with thin flat wings and it will still fly. Inefficient, yes, but I build balsa models like that for fun.
Some acrobatic airplanes have symmetrical (top-to-bottom) wings that fly upside down, just as well as they fly upright. And people sometimes fly upside down (at -1G) using wings that are optimized for upright flying.
I knew that from childhood because a paper aeroplane would fly. Many of the balsa wood toy planes from my childhood also had wings cut from a flat sheet of wood which was curved slightly by the attachment to the "fuselage". They would also fly perfectly well.
Only one of those three should be recommended, and that is Doug. The only video people should watch is his. Prof Babinsky uses a simplification that has existed in the literature since the 1920's, and it only captures the flow around the leading edge. He explains none of the transient effects that are important. It is as bad as all of the others, Coanda or Bernoulli, and it equates to "just look at this one part, and ignore everything else". It is very Wizard of Oz. Prof Fidkowski make the common engineering mistakes, talking about inviscid lift and does not address some key aspects. Doug's video, his book, and his articles in The Physics Teacher are amazing. He makes it clear that to calculate lift you are solving the Reynolds-averaged Navier-Stokes. The work by Prof Tianshu Liu from WMU makes it very clear that the Navier-Stokes are needed, given viscosity is fundamental for the generation of lift. That is, the Navier-Stokes are the fluid equations we have with viscosity (unlike Euler). So, Magnar, I am sorry to say that you are also incorrect because what NASA have is incorrect. In 2D, where most of the fundamental airfoil data comes from, flow does not accelerate downwards, it returns horizontal, and you can show the lift force as a the pressure difference between the upper and lower surface on the wind tunnel, which is what NASA measured back in the 30's and 40's to characterise all the NACA airfoils. So, while Newton's 2nd law, which must include pressure and viscous forces, will show a momentum flux across an airfoil, it will not be equal to all lift. In fact, this was shown by Prandtl back in 1919. The most important point is that lift generation is a transient effect, where by viscosity if the fluid results in a vortex being shed at the trailing edge, which due to conservation of angular momentum results in a bound vortex around the airfoil. This is what makes the flow over the top faster, and the flow under slower, this then equates to lower pressure above and higher pressure below, which is the lift force.
I dont know what you think pressure is but for sure its the air hitting the underside of the wing (actually all sides). Infact pressure measured at the surface of the wing (or any other surface) is precisely the amount of force being applied by impacts of the air molecules onto the surface (by definition). This is why, for example, pressure increases with temperature (as the air molecules have higher kinetic energy on average, and its also why we have ideas like density altitude). So saying the pressure is higher under the wing than above the wing exactly means that more force is being applied by the impact of air molecues to the lower surface than the upper surface.
Airports also consider prevailing wind directions. So runways at a 30° angle may be the best if the winds almost never are at 90° from the first runway.
Yes, I'm based at an airport with runways 12-30 and 23-5 and other than when a weather front is crossing and the wind is switching direction it is pretty much always straight down one of those runways.
What really scares me is that I have never taken a single class in aerodynamics... yet I still knew many of the things he said were wrong. Particularly the part about all airports and aircraft carriers have more than one runway are they are never at 90 degrees... you know... because I have eyes.
@@cardboardboxification and to miss the mountains regardless of airflow. and not all airfields have the luxury of two runways. I have landed on islands where a cross strip would be way too short, and for that matter the runways they did have were always bloody short.
The old abandoned santa susana ( simi valley )airport had a very small strip, the east side had hill that was cut away so exposing the runway for incoming planes.@@SuperSrjones
Neil does touch on this by pointing out that when the angle of attack changes from the pilots deflecting the tail surface with the elevator, the pressure differential over the wing changes. This only shows the internet has no chill.
I was working on my pilot licenses while in college pursuing my civil engineering degree. My hydraulics professor was the first engineer I had heard who was so perplexed at how many otherwise credible people had the flawed "understanding" of Bernoulli and lift. To this day, from the FAA publications down, that misunderstanding continues. It's hard to understand why it has not been corrected after having been explained by so many sophisticated aerodynamic experts like those Magnar refers to at the end of his video.
Yea, I was gonna say the same thing: it's hard to blame Neil about Bernoulli when he's basically saying the same thing the FAA taught me while getting my pilot certificate....
@@davetime5234 This sounds like a Business Accountant speech. Going in with an engineering mind I am fascinated about how friction (drag) can from a fast flow can pump air in the boundary layer against a pressure gradient.
@@davetime5234 The Navier-Stokes equation is not consistent. And it is not real because fundamentally, atoms are particles and not a continuous fluid. There is some band aid available to get a numerical solution. Stick to typical bounding conditions. Include diffusion (thanks to the particle nature). That said, stall can be reliably predicted by xFoil even on an old PC.
Neil seems to be getting careless. Air does not "want" anything. It is a group of molecules under pressure due to gravity. I assure you, air does not want anything, just as water does not "seek its own level". It is water. Water seeks nothing. Words matter, Neil. 🙂
Yes, what you describe is somewhat of a problem these days. It's not just Neil tending to anthropomorphize like that while trying to explain some aspect of Physics.
@@jokerace8227 This anthropomorphic mindset has reached insane levels in IT. Ascribing aspirations, dreams and goals to elections and transistors is a deep form of bullshit, but seems to a big part of many AI discussions. Malicious programming and programmers, perhaps, but many seem to believe that a device can have a mission, dreams and goals outside of its program and programmers.
He has the difficult job of making science understandable to those who have insufficient instruction in science. The U.S. has been falling behind in that since the 80's.
Using the definition of NASA: "Lift is a *mechanical* force. It is generated by the interaction and contact of a solid body with a fluid (liquid or gas)" then, in a *strictly mechanical sense* only the lower part of the wing is able to generate lift in steady horizontal flight. By definition, no force is able to get a "grip" on the upper part of the wing (the outside surface which is in contact with surrounding air) and *pull* the upper part of the wing upwards. There is no pulling force on the upper part of the wing. However, because of the angle of attack and the fact that the wing is not moving through a vaccum but through pressurized air, the upper part of the wing is able to decrease the ambient static air pressure exercised by Earth's atmosphere, therefore less air molecules are hitting against the upper side of the wing pushing it downwards, but this is not lift as lift would be directed upward, not downward. So at all times, air is only pushing against the upper part of the wing pushing the wing down and that's why those diagrams here: 8:56 are wrong as they depict force vectors pulling the upper side of the wing upwards. There is no mechanical force pulling the upper part of the wing upwards. However, there is a force resulting from static air pressure pushing at all times against the upper AND lower part of the wing. So the lower part of the wing is able to push the wing upwards as the upper side of the wing it is no longer pushed down as much because of aerodynamic effects (angle of attack, wing shape, air speed and so on). The wing moves upwards because of the aerodynamically created influence on the effect the surrounding static air pressure has on the wing (greater on the lower part) + the aerodynamically generated force of lift on the lower part. On the upper part, there cannot be any aerodynamically generated force of lift, only an *aerodynamically generated local reduction of the effect of static air pressure pushing downwards against the wing* (because of Bernoulli) therefore diminishing the downward push of the static pressure on the upper part of the wing. Therefore not every surface on the wing produces lift, but every bit of the surface influences how air moves around the wing and how the airflow is bend. Also, in case you don't understand this argument: if you buy a vaccum suction cup holder, once installed on a window pane, it actually does not suck on the window to stay put. The part facing the window pane can be compared to the upper wing, the part facing you can be compared to the lower wing. So the "vaccum suction cup holder" remains put because static air pushes it against the window pane (that would be lift) the only difference is, in order to create it, there is no need for airflow because the surface facing the window is hermetically sealed of and the lower static pressure is permanently maintained so there is no need for dynamic airflow over a curved surface at an angle of attack in order to create a local reduction of static air pressure hitting the wing. Now, it would be foolish to say the inner part of that suction cup holder created "more lift than the outer part" - as no force is pulling the inner surface against the window pane, only the outside static air pressure is pushing the suction cup against it.
It's a matter of semantics whether you want to think of it as suction or not. It's a pressure differential. When you turn on your vacuum cleaner does it "suck" up the dirt on the floor or is it the wind, caused by the air trying to equalize the pressure differential, that is "blowing" the dirt into the hose? Most people are going to think of it as suction.
Ive made planes with flat pieces of balsa for wings and they still fly. You don’t need the tear drop wing profile for low and high pressure. The high pressure will create on the low side by simply tilting the wing angle of attack (flat piece of balsa) at a steeper angle.
Tear drop is for fuselage to reduce drag. I once got a balsa plane and am still mad that they did not machine it the slightest. So difficult to sand the edge down.
I had this discussion about "lift" with my CFI, so I do not claim to know everything but I have a pretty good grasp on what's going on. Bernoulli's principle definitely applies buts its SECONDARY to a much greater effect, that would be Newtons 3rd Law of Motion which states "For every action there is an equal and opposite reaction". Now as you increase lift you therefore increase drag, you can see this in action during a turn where you get adverse yaw. In regards to lift, as the air hits the wing at whatever angle on the underside you get downward deflection which causes drag, well the equal and opposite reaction is LIFT which pushes the wing up in conjunction with Bernoulli's Principle and that is in very basic terms how a wing works. Once you exceed the CAOA (Critical Angle Of Attack) the wing is no longer producing lift, so that would be the stopping point of lift generation in flight, on the ground you need sufficient airflow to generate lift, when not generating enough airflow under the wing on the ground you stay grounded. For those of you saying "So what you are saying is, if I went fast enough or the wind was strong enough I could fly?"... technically yes, I mean a Tornado can certainly give you enough airflow to offset your weight and drag.
as a kid in elementary school, one day an airline pilot came to the school to teach the class about how planes work. She used the equal transit time explanation to show how lift works, and unfortunately by the time I had learned that that wasn't entirely accurate, I had already been sharing that incorrect information for years.
regardless of if the flows come together at the same time or not, the top flow moves faster and thus drops the pressure and lift created. Compressibility of the air was left out for whatever reason, but it works, every time I take off. Nitpickers will be nitpicking, just let me fly.
Tyson is one of those people who, while obviously very knowledgeable about many things, is also full of hubris and seems to want to always be the smartest guy in the room. I've known several people like him - smart but overly confident about what he actually knows.
no, Bernoulli always plays part when air velocities are different on both sides of the airfoil, you always can calculate lift knowing the distribution of velocities, upside down has nothing to do with it
feel like hes trying to dumb it down compacting the whole thing trying to relate, but it makes it only more exhausting and even wrong. If he wants to communicate it, maybe he should make animation or practical demostration, but he sits there trying to convey. Also taking his sweet a time with it
Thank you Captain for a great explanation. I was taught the wrong way and no explanation was ever given as to how an air particle going across the top "knows" it must meet it's slower moving buddy at the rear of the wing at the same time. We were also never taught exactly WHY and HOW the airfoil curve causes faster airflow along the top. Your explanation and the NASA site at last clear it all up. NDGTs best move now would be to own the mistake and make a new video.
Aïe !!! at 9:05, green AND blue are low pressure. Above AND below wings, there is LOW pressure. The deficit of pressure above is more important than the deficit below, so the summation gives lift. On the diagram at 9:05, green AND blue are low pressure (don't look at the arrows). The size of green (above) is bigger than the size of blue, so there is lift.
I recently saw him talk about landing the space shuttle. He claimed that NASA discovered that putting linear grooves in the runway would straighten out the shuttle when it landed. The Dept. of Transportation had been putting grooves in the highways and freeways before NASA even existed. They do this to help the road shed water when it rains to avoid hydroplaning. I've driven on these surfaces for almost 50 years and I can tell you that a grooved surface does NOTHING to keep a vehicle going straight.
I suppose then he thinks they are "self driving roads" just set your cruise control, let go of the wheel and begin watching Tyson DeGrasse vids for a few miles, no worries mate! Grooves would help tires skidding sideways in a crosswind to some degree essentially "steering" it. The shuttle landed at a high angle of attack and spent a long time with the main gear on the runway holding the nose up, letting it settle slowly. The load on the mains is very low for a while because of ground effect and the high angle of attack. every time the pilot inputs a rudder command to keep the shuttle straight in a crosswind, it causes a sideways force on the main gear trying to rotate the nose in the opposite direction. This is because they can't bank it to counter it while the wheels are on the ground. Applying the rudder without banking when flying is called "skidding" you do this to point your nose more into a crosswind to fly a straight course, using a portion of your thrust to counter the crosswind. This creates drag. In a small, slow, plane and a large crosswind, I have actually flown a course forwards by looking out the side window! That's fun when using a compass to navigate since you have to make a correction because the plane rotated under the dial. You are doing the same thing in a plane in a crosswind landing, you are "drifting" the aircraft. You can also use the engine to pull you back over the runway. The shuttle is a glider, this means they can't go around, and can't power it back over the runway if things get out of hand. It's actually an amazing piece of flying to make an "engine out" landing every time! The sooner you stop the skid the better because when the mains finally "bite" at a high angle to your line of travel they throw you to the side, and you can begin fishtailing.
To accomplish this the grooves run DOWN the runway or road. They do help with skidding. Concrete is very smooth, therefore hydroplaning is more of an issue because water has a harder time getting out from under your tires. Groves help with this especially cross grooves.
Thanks for confirming that this comment section is just unearned NDT hate. The grooves WERE invented by NASA in the 1960s for the space shuttle: "NASA developed grooved runways in the 1960s to improve traction and reduce hydroplaning for aircraft landing. The technique involves cutting grooves into concrete surfaces with diamond blades to help water run off, similar to how tire tread patterns increase traction. NASA engineers discovered that grooved runways could significantly reduce accidents. The Kennedy Space Center's landing strip was safety grooved for the Space Shuttle, and the technique was later applied to highways, stairways, sidewalks, parking lots, and other surfaces."
Ok, so, there is a temporary climb generated by excess lift. However, I'm going to say that airplanes' rate of climb depends on their excess power, and their angle of climb depends on excess thrust. Airplanes fly because of lift, but they climb because of excess power and thrust. Gliders climb due to thermals, which is an external source of energy. Rockets climb because of excess thrust. The decrease in pressure above the wing at sea level is more pronounced than the increase in pressure below the wing. But, if you consider an aircraft like an SR-71, in the near vacuum of high altitude, there is almost no atmospheric pressure to remove from above the wing. Therefore, the aircraft resists gravity only due to the upward force of the pressure beneath the aircraft. All aircraft fly because of that same reason.
Magnar, lift has less to do with de pressure difference on the surfaces on the wing than we think it does. Take a spoon, turn on the kitchen water faucet and put the concave part of the spoon into the water stream. The spoon will get pulled into the water stream at a aproximative 90 degree angle (lift), even tho there is no water flowing on the convex part to make a pressure difference. Lift is a 90% upper wing surphace phenomenon.
I had not listened ot Tyson's explanation previously, but it sounds like a simplified Physics class that ignores the complications of the real world. It reminded me of the joke told to me by one of my Physics professors in college to stress that point: "Physics is the study of frictionless elephants whose mass can be neglected". The forces on the air do indeed act to "keep it at one parcel", but real-world forces like friction and the energy imparted as the wing moves through it prevent this from happening. Terms get complicated depending on the frame of reference that is being used (ie. whether the wing acts on the air, is with an aircraft, or the air acts on the wing, as in a wind tunnel). At least Tyson discussed angle of attack and its effect on lift. Some drawings used to explain lift show the airfoil at an angle of attack that produces either no lift or sometimes even a net downward "lift".
Wel, holding your hand out of your car window is still a good analogy for a wing. A poorly designed wing but a wing none the less. You do not need an airfoil shape to achieve flight. A cinder block will fly and be controlled with enough thrust. The airfoil shape is more efficient at creating this effect of being sucked up like a noodle by the lower pressure air as this air is sucked down into the upper shape or surface of the airfoil. It's bernulis principle. It's a half Venturi shape layed on a flat surface instead of bent into a circle. A ram air engine of sorts. Sucks its way up and pushes that air downward. It's some wormhole stuff.
A cube can fly, just vector the thrust to apply all of the lift. Nobody cares about flying, everybody cares about flying with thrust that is much smaller than your weight.
Such a great video, even pilots often get this wrong, since I guess it's just easier to teach an oversimplified explanation to someone who won't ever actually have to design a wing, but great to see a pilot who really gets it!!!
The atmosphere is a closed system. Introduce an object into it and the air is displaced. The air has to go somewhere. Interject a wing form, give it speed and air has to go around it. Some goes faster that the other and a low pressure is created and the void displaced. The wing moves to the area of less pressure. The wing lifts.
He states the air just "wants to" reach the same air particle on the other side - but doesn't question by which mechanic this air particle can do this. Thank you Magnar for being a great teacher.
yes it is harder to increase preassure under the wing than lower the preasure over the wing but it doesn't mean that Tyson is wrong, lift is generated by air hitting bottom of the wing, preasure is molecules of air hitting surface, there will be no lift without high preasure under the wing
And this is why he needs to stay in his lane. My home airport of Plant City Municipal Airport(KPCM) only has one strip and 2 runways. There are airports that can have 2 strips and only 3 runway, not 4 like you would think, because one end is not used for takeoff or landing due to obstacles(but usually due to rich people). Also, where I used to work at Igor Sikorsky Memorial Airport(KBDR) has 2 strips and 4 runways(used to have 3 strips and 6 runways), and the two remaining strips are RWY 6-24 and RWY 11-29.
Neither of you are correct, even your video contradicts your statements. Freeze the screen at 4:31 and take a thorough look at it. It was not the air above the wing that became faster (see the uppermost smoke line at the very top of the screen matching the one right above the wing), but the air below the wing has slowed down due to the pitched position of the wing. In this specific experiment the pitched position of the wing was a more substantial factor than the wing profile. You can fly even with a completely flat shaped wing if it is pitched as it will create a pressure delta on its own.
Insightful point. The author of the video could have easily just shown the case where the wing was level but he didn’t. Why not? I’m suspicious that it would have shown the two airstreams arriving at the Sam time.
As a sailing instructor I sometimes had students who knew all about Benoulli's theorem. When I pointed out that a sailboat's sail has no thickness, I was met with disbelief. "How dare you question Benoulli!" Newton's law of motion explain airfoil lift nicely. Those infatuated with Benoulli have to resort to Newton when challenged on the inconsistencies.
You are100% correct to question the use of Bernoulli's theorem in sailing. But whose explanation do you use? Marchaj? Gentry? Fossati?, North Sails? ...?
Coandă effect There are many principles at play with an airfoil. Newtonian physics is the ultimate explanation, because lift or any aerodynamic force is due to an equal and opposite reaction to an air mass being accelerated. Air mass is accelerated (deflected) Either by a moving surface at an inclined angle of attack, or by another deflected surface attached to a primary surface which is moving at zero angle to the relative wind. The how and the why of this air bending is explained by Bernoulli, Coandă, et. al.
@@RationalDiscourse As I said, an angle of attack deflects the airstream in one direction which results in the equal and opposite force in the other direction. Newton.
@@Triple_J.1 Without an angle of attack there can be no lift. Your "zero angel to the relative wind" idea is not correct. If the airfoil is producing lift, it has an angle of attack. The fact that the bottom edge of an airfoil is parallel to the wind direction does not mean that the airfoil has a zero angle of attack. Tha angle is defined by the cord of the angle of the two sufaces of the airfoil have at its trailing edge which results in a downward deflection of the airstream.
@@davetime5234 I am not imposing such a condition. One side of the sail developes higher pressure because it is pushing the airstream in a new direction. On the other side of the sail the airstream wants to continue its direction according to Newton's laws of motion. However, that continuation results in a vacuum because the sail curves away from the direction of the airstream. That lower pressure induces the airsteam to change its direction and follow the curvature of the sail. Newton's laws are all that one needs to explain why a sail devlops lift. Sir, you are the one who is imposing conditions with your "contoured airflow" hypothesis. Bernoulli is NOT "essential" for explaining lift.
Airport runways are oriented to the prevailing winds at their location. A wind rose helps illustrate prevailing winds, and it can be informative to compare a location's wind rose with its airport runway(s). The runways are most likely NOT 90° to each other (though it can happen).
Finally, a sufficiently concise video on lift. I took a super intriguing online aeronautics course with TU Delft, and got quite annoyed when I had to take an intro physics class in college. Bernoulli is an insufficient explanation of lift; I prefer to talk about the Newtonian aspect, angle of attack, and drag. Edit to add: the aeronautics course was taken through EdX
It is interesting that two of the world's leading astrophysicists, Tyson and Kraus, rockstars of their field, think they can bang on about everything. I especially dislike their hubris, the emphatic way they pronounce their opinions. A real scientist is careful and uncertain - because science is a set of hypotheses which are only correct until we find something better. In consequence, I have no time for such people - because if they are wrong about a subject I do understand, they might well be wrong about everything.
It is a stretch to call Tyson an astrophysicist, much less one of the world's leading astrophysicists. His C.V. is easy to find online. Five 1st author papers, all from the 80s and 90s. In 2008 his name appears very late in long lists of authors for the COSMOS review papers. Were those five 1st author papers during his college years outstanding? No. Harvard turned him down for post grad. At University of Texas they dissolved his doctoral committee, essentially flunking him. His advisors correctly told him he had no aptitude for astrophysics. Most of Tyson's career has been flashy and often inaccurate pop science.
Nobody is omniscient but that doesn’t make them wrong about everything. Tyson gets people interested in science and we need a hell of a lot more people like him because way too many people treat science like another religion these days. You take what knowledge you can from people but verify what you’re being told and don’t just blindly trust the cult of personality. On the flip side, whenever a smart guy gets something wrong, there’ll be a long line of people gleefully piling on to stroke their own ego.
@@Danimalpm1 Does Tyson inspire a deep interest? If so why is it his fans usually don't notice his errors? His bad math and science is merely annoying. I do not care if he tells his pseudo nerd fans that there are more transcendental numbers than irrationals. Or that the James Webb Space Telescope is parked at the sun-earth-l2 point in earth's shadow. What makes me angry is when he uses his wrong history to underscore his talking points regarding politics and history. Using falsehoods to push a narrative is a serious offense,
@@HopDavid Snake in DeGrasse Tyson is an establishment guy. Science is what the government _tells_ him it is: he re-packages their politics, dressing them up as science and then spews propaganda on behalf of Big Pharma and the ICC.
8:51 it’s meant to be drag, but in the wind tunnel experiment earlier the angle of attack of the wing was not flat. i always think it seems like a lot of it is the change of angle of the air rather than pressure change
As a paraglider (ridge soaring) we use the air flow over hills to gain lift. It's quite odd, because it's been described to me as being the same thing that happens in the first 1/3 of a wing chord. However the "upward" deflection of the airflow over the mountain creates a much high band of lift just in front of the summit. The upwards vector of the air there can extend hundreds of feet above the hill, even without any thermic effects. The danger is what happens on the "back side" of the hill. Being there in a paraglider would be no less dangerous than going through a river rapids in a childs blow up dingy. You can't see air. However you can visualise it as water. The front side of the hill has an accelerating laminar flow. The back side is tumbling crashing waves of down draughts and the resulting rotors. When I asked my instructor, "So how bad is it if you got blown over the back?". His answer was short. "Back breaking."
Runway directions are chosen by monitoring wind conditions for a period before aerodrome construction which @gcpgrey did a video on. They aren't at 90 due to laziness . Nzch has it because wind commonly goes north south (02/20) but occasionally off the mountains (27/11).but klas doesn't have 90 diff. This is because analysis shows common wind directions.
Right. Ideally, the runways will be situated so that most of the time, one will be aligned with the wind. If the wind is mostly from a narrow range of the compass, they might build runways that cross at a narrow angle. Although a lot of airports have to contend with geographic constraints and can't have ideal runways. The busiest airports have parallel runways with no crossings because that's the best way to serve many planes in quick succession. Modern transport category aircraft can handle huge crosswind components, so they don't always have to perfectly align with the wind.
@@mickster04 No, he doesn't say they're always at 90. He just says that putting them at 90 is the best solution if you want to be best able to cope with every wind direction. (And the runways at KDEN are at 90 degrees to each other.)
As an engineer, I think you are splitting hairs to debunk NDGT. He is trying to educate a lay audience at a level that a non scientific audience can grasp. And he does that extremely well. If you want to argue with his science, look for the papers he writes, critic them with other scientists.
I took aviation mechanics in the late 80s and what Mr Tyson stated was exactly what was taught. The instructor even used dots to show the path taken by the air flow and the dots aways met up. Its been decades but I can remember plotting airfoils using stick pins and string. My instructor was a licensed pilot with the following ratings; instrumentation, multi-engine, instructor and was a licensed A/P mechanic. He never stated how many, but he spoke about the times he assisted in a crash investigation and a local kit plane producer in addressing undesired flight characteristics.
Neither pilots nor mechanics need to understand the physics of flight. They are practical disciplines. As a physicist, NdGT ought to be able to look deeper into the matter, but that doesn't seem to be his objective. He has become an entertainer, not an educator.
Thanks for clearly explaining how he is wrong. Neil has his finger in every aspect of science, philosophy, etc. He's full of himself and he really believes he knows about everything in this universe.
It's actually a little bizarre that NDT got this so wrong. I mean if he thought for a moment and recalled - for example - that many airplanes regularly fly inverted (and that most airfoils don't look like his example and many are close to symmetrical about the chord line) he'd have to realize that his explanation was flawed. And don't even get me started by the "up the flaps on the tail wing" part. Sigh. Thanks for the video Magnar!
I watch occasionally videos from NDT. Sometimes I don't have enough knowledge of the topic to call him false but this time about airplanes and airport configurations he hit right at one of my best topic. He was pathetic the less I can say. - NDT "Airplane must always take off facing the wind" FALSE - NDT "pilote raise the tail flaps to raise the nose up" WRONG it's aileron. There's no flaps there and flaps on wings have a complete opposite purpose - NDT "Airports always have two runways and are never in a 90° cross over to give more possibilities of taking off up wind" FALSE and FALSE - NDT "When the plane accelerate it comes a momentum where the plane pop up suddenly to the sky. It's not something happening smoothly and progressively" FALSE bullshit and of course the Bernoulli explanation... Like someone else wrote here, if NDT can be so wrong about a topic I perfectly know, how much bullshit he can say on topics I don't know enough to call bullshit?
@@laurentsamson8927 You claim he said that airpcraft must always take off into the wind. FALSE. He says that, _given the choice,_ they would take off into the wind. As for the "tail flaps" thing, sure, but he just doesn't know the right word. That's not the same thing as failing to understand the concept.
Before watching the video. Lift has to do with air mass and the speed of travel. You create a vacuum area on a wing which makes it move into the void. Which isn't a void but less atmospheric pressure ??
I learned a lot about lift from making balsa aircraft. When the velocity of the air is low and the mass of the wing is low, it's very strange how a wing responds in your hand. It defies intuition. On the other hand, aircraft can fly upside-down, making it clear that there is more than one way to generate lift from a wing.
Neil is one of those giant heads who claim to know more than he actually does. I was a fan of his for a short time until I realized he’s not as smart and knowledgeable as he thinks he is.
The logic of building two runways on an aircraft carrier so that one of them is always facing into the wind is amusing. Why wouldn't the captain tell the guy at the helm to turn into the wind. Imagine that conversation. Captain: OK, turn into the wind. Guy at the wheel: We can't Captain, we didn't build that runway. I can't wait for his dissertation on rudder theory.
I want to beat my head into the fireplace hearth hearing him explain this very incorrect thought. Seriously, where did he even get that from? The angles are only 14 degrees or so off one another. So that’s not giving you many options to “always” have a runway pointed toward the wind. And the super know it all tone in his voice when being so wrong! My forehead needs a bandaid.
So it’s complicated and lift is complimentary 🎉 Neil was trying to make it too basic. But the idea is correct, the displacement of air downwards by increasing the AoA is a key part of lift, assisted by the lower pressure on the upper surface
It's not making it basic that's the problem. It's telling the unnecessary falsehood that air packets meet up again at the back of the wing. If he'd just said that the air goes faster over the top, so the pressure is lower, that would be acceptable as an explanation. But he gives a completely bogus explanation about _why_ that happens.
@@davetime5234 Yes it is. A helicopter is a 'rotary wing aircraft'. Downwash from the rotor blades is a [wasteful] byproduct that - to a casual observer - could be mistaken for "thrust" (think about this: if rotor blades were literally producing only downward thrust to generate lift, no one would ever be able stand under a hovering helicopter as the downward force produced would exceed the weight of the helicopter for it to fly). Helicopter rotor blades are in fact, 'wings' with a very narrow chord, and produce lift in the same manner as a fixed wing aircraft, the difference being that the wings (rotor blades) of a helicopter travel along a circular path to create lift, rather than a linear path like airplanes.
@@FailedTheTuringTest I'm not sure if I understood what you're trying to say: "if rotor blades were literally producing only downward thrust to generate lift, no one would ever be able stand under a hovering helicopter as the downward force produced would exceed the weight of the helicopter for it to fly" The force under a hovering helicopter is enormous. The downward change in momentum of air must equal the weight of the helicopter. I once stood near large heavy steel barrels that were thrown down by a helicopter's down wash. Also, a turbo fan engine, or a turboprop blade, or a piston engine propeller on a C152. We call the force in all such cases "thrust". A helicopter blade is no different.
I've seen many experienced pilots and others describe the equal transit time theory. Starting in jr high school when I did a science project on Bernouli's principle. The upper wing actually forms a venturi between the wing upper surface and the air above. But not all wings are flat on the bottom and curved on top. Some are nearly symmetrical. Such as the laminar flow airfoil on the P-51.
Agree with most of the other posters however the statement about all airports having two runways is correct. For instance at our home grass strip has a single strip of land runway 9 and runway 27 which you would announce to other aircraft so they know which way you are taking off or landing.
Ok, you're obviously correct in all you said, you are discussing this from a professional airline pilot view, which is fine, Neil Tyson is not a pilot and his videos are more of the informal kind I guess. He tried to explain things in a simplistic way and by making a lot of assumptions on things he probably doesn't know that well. I think he did ok-ish, maybe he could be prepared a bit more on subjects he speaks about, but if he makes someone else read about those subjects or look them up, or cause a reaction video from an actual pilot, that's still a win I think. Sometimes, people will look for super accurate explanations, sometimes they just want a not too accurate and relaxed summary. Thanks for the video. :-)
Simplifying is fine, but NdGT's explanations are just wrong. Simplifying would be saying that the air on top of the wing goes faster, so is at lower pressure. But claiming that the air goes faster because packets of air that get split by the leading edge of the wing have to meet up again at the trailing edge is just wrong, in exactly the same way that claiming that planes fly because invisible pixies push up on the bottom of the wings is wrong. His claims that two airport runways should be at 30 degrees to maximise the possibility of taking off into the wind is false in the same way that "2+2=3" is wrong. (Putting them at 30 degrees means you might have to take off at 75 degrees to the wind; putting them at 90 degrees means you'll never have to take off at more than 45 degrees.) His claims that most airport runways are at 30 degrees is trivially disproven by looking at a map. He lives in New York: JFK and LaGuardia have runways at 90 degrees and Newark's main two runways are parallel and the third is at 70 degrees to them. His claim that aircraft carriers have two runways to allow take-off into the wind is flat-out wrong, and obviously so, since aircraft carriers can move, so can always be pointed into the wind.
One of the great challenges in this world, is knowing enough about a subject to think you're right...but not enough about the subject, to know that you're wrong...
Dunning-Kruger effect
@@BritishBeachcomber That-s typical among Scientism adepts. You can find a lot of PhD holders who are dishonest idiots
My favorite example is a PhD in MATHEMATICS who said 10^12 > 10^23 just to slander the target of his hatred
An even greater challenge is knowing when you're being hoodwinked by social manipulators who are actively molesting you and insulting your intelligence by directly appealing to known preconceived notions and preferred (habitually maintained) bias, while making you believe they're "clarifying" something for your intellectual benefit. See my other comment for more details
That's Neil describing his entire career.
That ad drives me crazy.
Neil gets A LOT of things wrong.
I for one appreciate that he actually got the "lift" concept correct, aside from the speed of the air concept.
But explaining lift is as simple as saying that air *does* push up on the wing because there is a greater concentration of air molecules below than above it on the other side, and the forces aren't equal. AKA "static differential". The wing, being between these two pressure zones, will want to move in the direction of least pressure... generally "up" in a plane.
Bernoulli's principle is virtually a separate "issue" and is only the *cause of the differential* pressure.
Just look at the smoke trail clip. Notice how the smoke is spread out above, and highly concentrated below.
Not sure why this is such a difficult concept for people to grasp. No need to over complicate it until you need to do the actual math.
Lift is cause by action and reaction - molecules been deflected downwards, which cases lift.
The pressure differential is a reaction to the deflection of molecules, not the cause if lift.
R
@@RalphEllisCorrect. F=Ma. The amount of lift is equal to the mass of the air and how much it is accelerated. Maybe not equal but that’s essentially it.
That's what happens when you buy into your own hype.
Are you a creationist?
I went to engineering school with guys like NDT - so eager to teach and or sound smart that they have to sound authoritative in everything, regardless of how little understanding they have of whatever topic they're wandering through at the moment.
Thats wild. I only went to university with purple haired activists, furries and CCP infiltrators.
So did I. I was shocked at how many people knew so little about what they wanted and tried to teach. I'm now a pilot and was tutoring someone on instrument flying. Another pilot who didn't even have an instrument rating kept interrupting to also teach the student. He NEEDED to be the center of attention and seen as smart. It was a pathology he didn't see in himself. After he finally left the room I told the student to completely disregard what he interjected. And since then I would never have him near the controls of any aircraft I was in.
Thomas Sowell's book "Intellectuals and Society" talks about this phenomena and makes some interesting points about it.
@@timn4481 I didn't intend to claim he doesn't know much, he's obviously very intelligent, and so we're my engineering peers, but he and they had this attitude of, "I'm good at a difficult subject, therefore I must be smart about all other subjects." You can tell he's thinking about some of this stuff for the first time, and assuming that as he solves the issue(s) in real time while discussing them he must be coming up with the same solution that others had already figured out over the years. In this case: runway configurations at airports.
He is a DEI hire
Tyson is living proof you should never rely only on social media for accurate information.
A man who truly loves the sound of his own voice.
You mean Tyson, right?
@@KutWrite Yes. NDT is a diversity hire. He believes in lots of BS items, like multibverses.
Kutta Joukowski Theorem
@@KutWrite or trump
@@elmalloc Wow... Love the fact that Trump lives rent free in your tiny brain.
Tyson’s greatest work was Cosmos where he was reading from a script written by people who actually knew what they were talking about.
Hes a total fraud.
I thought Tyson wrote it. So I just looked it up. You're right.
There are MANY aerodynamics engineers that get this wrong because it IS what we were taught in college back in the 80s and later years. It wasn't until later that some professors put their videos on youtube to correct the mistake. So that he got it wrong isn't surprising nor does it mean he doesn't know what he is talking about with respect to other subjects just as I posted.
@@FlyingAceAV8B No he isn't, I as an aerospace engineer was taught this too. It wasn't until later that it was corrected.
@@diegom8
>> There are MANY aerodynamics engineers that get this wrong
This is maybe the most basic thing in all of aerodynamics. If an aero engineer today gets this wrong, they have been in a coma for 40 years. This is roughly equivalent to a doctor using blood-letting.
I'm gonna correct one thing - he wants us to think he knows it all. I wish he'd stick to topics he really knows, but he likes the sound of his own voice, so I know he won't stop.
I'd blame the current need of "marketization of the self" nowadays more than him "liking the sound of his own voice".
If you want to stay relevant as a 'product', you need to keep pushing out content, so ppl like deGrasse Tyson push themselves out of their zones of actual knowledge.
Same goes for many of the science communicators on SoMe. Another example is Sabine Hossenfelder, and I'm sure you can find many more that have started within their fields of expertise, but then started reaching outside of that and start getting things wrong.
@@Jarlerus It wouldn't be surprising for mistakes to crop into anyone's work, particularly after making a lot of videos, but are there examples of videos from Hossenfelder where the entire video is wrong or misleading?
@@oliverbatt3559 Videos with outdated, limited, and narrow perspectives. Often around more politicized topics. Still, it shows a lack of actual expertise in subjects. Just like the Tyson video referenced here; The explanation is simplified, parts of it (f.ex. how Bernoulli's is explained) might be correct, but the whole lacks a lot.
What topics does he really know? I've watch him botch history, biology, medicine -- even basic physics and astronomy!
@@HopDavid If you can do a better job, you should give it a go. We need more people advocating science for people too lazy to put in the work themselves.
Tyson is NOWHERE as smart as he thinks he is.
Unfortunately some people take him as a prophet
Most people are not (myself being no exception).
Who is?
@@EdreesesPieces Literally thousands of people have a better grasp of reality
His take on helicopters falling like a brick in the event of an engine failure was disappointing. Just a quick Google search would answer it. But I have a feeling he doesn’t feel the need to Google much.
Listening to Tyson talk, it boggles the mind how anyone ever took him seriously.
Because he has a PhD in physics and you’re standing on the sidelines with a magnifying glass
As someone with a PhD myself, experience has taught me to tend to count that against someone rather than in their favor.
Years ago before he was exposed as a hack, I listened to him on star talk explaining that elon musk could not accomplish the things he is doing easily today, and that the privatization of space would never happen, and this should always be the governments job. Then went on to explain incorrectly fundamental aspects of rocketry
perception is what matters, learnt it the hard way.
When Tyson passes away, nobody will say "We lost a great scientist today"
As a pilot, listening to Tyson's explanation of lift was like listening to fingernails on a blackboard... Also, anytime anyone says that natural phenomenon "wants" to do something, it's time to change the channel.
Yeah, that was the first obvious error. After all, once the parcel of air has been split by the leading edge of the wing, don't the two halves want to get as far apart as possible, like any recently split couple?
Agree with your annoyance with the use of “wants.” Anthropomorphizing physical phenomena generally conveys lack of competent understanding.
Surely he is using such expressions to resonate more with regular people, that have no physics and technical knowledge about the subject
@@MStoica I disagree. Speaking and writing as if physical phenomena (such as air molecules) have conscious volition _is not_ helpful or instructive to subject-matter novices. Better is to explain in a manner consistent with the know science, yet slowly and carefully and within the audience’s capacity to comprehend. Often, the false attribution of conscious volition is an indication that the speaker himself doesn’t fully understand the subject matter.
@@MStoica If he's purposely spreading falsehoods to build his follower count, that's even worse than his own not understanding the subject in the first place.
Magnar, well done! I too watched the Neil deGrasse Tyson video (due, in part, to his celebrity status), only to find myself muttering “no, no, no ….”. Thanks for putting together such a well researched, technically correct, exposé of three common misconceptions in aeronautics.
what are the other two?
Except its wrong. His examples were not for straight and level flight. 🤷
@@mrphysics2625 All the examples work the same in level flight.
From the outside, it appears that Mr Tyson's self worth is wrapped around being the smartest person in any room he enters. And it doesn't seem like that meshes well with the final quote in this video.
Lao Tzu - The wise man is one who, knows, what he does not know. And its corollary - Stay in your lane. In short, no one has a good grasp of everything. When one thinks they do, that's precisely when they get into trouble.
The Dunning-Kruger effect. He doesn't know what he doesn't know. But he thinks he knows everything.
dull... he and BO are the dumbbbbbest in any room.
He’s successful because a frustratingly large ratio of ppl respect charisma more than intelligence. Say the thing dramatically and commandingly, and ppl will think there’s substance behind your confidence-but that’s only because most ppl aren’t bold enough to lie that well.
Bravo
My high hopes were crushed as well after I saw ND Tyson's video. Aero Engr here. Kudos on your rebuttal. Well done!
Transit time rebuttals still fail to make a strong case with respect to the necessary mass flow continuity condition.
I love it when you can ‘see’ the low pressure envelope above a wing when planes are close to landing in wet humid conditions. That cloud above the wing.... now you see me, now you don’t. The same conditions also show the powerful vortices coming from the outboard tips of the trailing edge flaps. When lift and wake air turbulence become visible.
A perfectly flat panel, with no curvature, generates lift. Small wooden children's toy airplanes use flat sheets for wings, and they fly just fine. Properly curved airfoils can increase lift efficiency. Cantilevered wing tips can help with reducing vortices, thereby reducing stall speed. There are optimal designs for these also. Long thin wings are more efficient than short fat wings at generating lift, but long thin wings are more susceptible to turbulence. Each blade in a jet engine is a type of wing.
I used to like Neil’s science descriptions. Then I saw him give a keynote live at a technical conference in San Francisco. I forgot what topic he was talking about, but the number and level of bombastic arguments and assumptions was counter to what I learned from my scientific mentors. (Three of them are notable enough to have Wikipedia articles.)
But upon watching this (and I’m only at 11:30 ), my level of Picard facepalming has reached a new level. How does he get these cowpies past his fact-checking team?
You’re insufferable
DeGrasse isn't just in the wrong lane here, he's on the wrong highway!
Wrong runway
He always pontificates on subjects that are not his field
and not just on this topic. Never has a "scientist" fallen so deep as NdGT
He is not much better with the subjects is supposed to be an expert in.
Does anybody ask the question WHY? I bet he never did actual calculations on aerodynamics all by himself. Sure he CAN, but this video only leaves the impression, Tyson did not go into detail, here. Mind you, there is a whole lot more to know about wings and planes. The first supersonic planes went down like a brick, trying to kill the pilot. It took a while before it was clear what caused such problems. And that is just one example. See? It is even difficult explaining how wings work, before you know it, you are marketing an out dated theory.
And these weird tit for tat comments here, well, it doesn't make me happy, either.
Tyson ain't no Sagan, that's for sure...
Be careful....you will be called a racist because of this comment.
But I agree with you.
Sagan was scientifically sound.
@@christopheryellman533he made his own mistakes too. There was a whole segment in the original Cosmos about the burning of the Library of Alexandria and the middle ages which is entirely misinformation for example. Everyone has their blindspots.
@@AdamBrusselback A friend of mine was an undergraduate at Cornell, and one of his classmates worked in Sagan's lab. He said when he went in there to visit him, there were clouds of smoke from the good weed.
@@christopheryellman533LOL. I believe it.
NDT is evolving into Cliff Clavin from Cheers.
Hahahahahaha
Disagree.
Now every time I see him I'm going to hear Cliffy's voice......ann't that right Norm!
Oh man, what I’d give to see those two have an interaction on the show!
I respect Dr. Tyson, but it surprised me when he stated that a helicopter cannot glide if its only engine stops. I fly single-engine airplanes and helicopters, and I'd rather be in the latter when the engine quits.
Interesting. Do you chalk that up yo your autorotation skills, or are you saying autorotation has better odds than gliding, period? If the latter, care to elaborate please?
@@--SPQR-- I'd prefer to be able to glide so I have better choices where to land, instead of having to land on whatever's directly below me (roughly).
@@--SPQR--i guess autorotation allows you to land where you choose in a small area; a plane still needs a nice flat field or similar. though bush planes can land pretty easily in a small space
He represents the worst kind of 'know-it-all'.
I heard the bit about the air going a longer distance and wanting to "catch up" 50 years ago when I was 12. Seemed wrong to me even back then. Thanks for finally setting the record straight.
Same.
read my post!
Yeah, that smoke demo showing the top air getting back FASTER was a revelation!
@@davetime5234 I'm not trying to dispute Bernoulli; just sayin' that it's Newton that *entirely* accounts for LIFT. "Equal and opposite" is not "optional"!
Thanks for confirming what I have known as a pilot for years. Interesting to note, I still, on occasion have to correct certified flight instructors during bi-annual reviews, that bernoulli alone is not sufficient. In fact, there are still manuals out there that still teach it incorrectly.
And none that explain it correctly!
Angle of attack.
@@codetech5598 Sure, angle of attack certainly affects lift (and drag) but why?
a Bernoulli based configuration, does not even generate lift!
@@RationalDiscourse A higher AOA moves more air downward, like a variable pitch prop pulls more when the pitch angle increases.
As noted by others - if “Equal transit time” were correct then inverted flight would be impossible, as would flat high-speed wings that have no curvature. Holding angled cardboard out a car window forces it upward.
Even more importantly would be the fact that you'd be able to get the lift essentially for free without the annoyance of induced drag.
I was told flying inverted was just because the airplane had much more power to overcome the drag
That's a misconception. Inverted flight wouldn't work if equal transit time were the ONLY way to create lift. AoA can create lift AND the airfoil shape and resulting different velocities ALSO create lift.
Claiming that Bernoulli lift makes inverted flight impossible is like saying that the existence of pizza makes hamburgers impossible. BOTH exist.
Then you have explanations based on air flowing downward long after the wing has passed by. Such as mentioned early in this video. But that explanation violates the law of causation - the air going down later can't push the wing up earlier. Cause always comes BEFORE effect. The cause can't come AFTER the effect. The air flowing downward AFTER it has left the wing is a result, an effect, of lift - it can't be the cause.
@@thomasward4505 Put most simply, wings generate lift via momentum transfer. The airfoil redirects the flow of air downward (provided there is AoA or camber) and this results in a reaction force on the wing that both produces lift and drag. Conventional wings will produce lift inverted provided there is sufficient angle of attack. Symmetric airfoils will also generate lift in both orientations, but require that there is always some angle of attack or no lift will be generated as the airflow will be unperturbed. Conventional wings like those on an airliner are designed to generate lift even in the absence of AoA so that the plane can fly level during cruise to reduce drag. There is a lot more to it, such as the wing being “high performance” capable of generating large quantities of lift even at relatively slow speeds. This also comes with proportional amounts of drag (which is a lot) which is one reason jets have such large powerful turbofans.
@@thomasward4505 And fwiw flying inverted will generally require more power since the wing is not optimized for negative angles of attack unless it’s specifically designed for it. But most of the time inverted flight is impossible due to the design of the fuel and lubrication systems since they are gravity fed. The fluids will collect on the opposite side and expose the sump to air. I believe in fighter jets there are reserve lubrication and fuel tanks designed specifically for negative g’s that allow for brief periods of flight inverted. Also the famous “vomit comet” used for low-g training gets around this by having specific minimum requirements for the quantity of fuel onboard so that the pickups remain submerged even in near zero g.
A simple experiment I was shown in the 1960s, long before I gained my humble private pilots license, involved 2 pieces of paper. Take a sheet of, let’s say, copy paper and hold it horizontally, like a mouth organ, but just under your bottom lip. If you blow across that paper, even quite gently, the sagging sheet will lift to be horizontal in both directions, left to right and front to back. A more dramatic experiment is to hold 2 sheets of paper vertically, close together and up against your lips. When you blow between them, fairly hard, you will be rewarded with the noisy report of the 2 sheets flapping wildly against each other. These are but 2 examples of Daniel Bernoulli’s principle at work. Oh. another example, I experience it every morning, is the way a shower curtain is drawn inwards by the water rushing past it, same principle. Smart man that Dutch born Swiss mathematician/physicist! The other factor keeping aircraft airborne is that the wings push the air down, via the angle of attack, not unlike a water skier’s skis. This is well illustrated by the slight drop in altitude noticed when an aircraft moves out of ground effect immediately after it leaves the end of the flight deck of an aircraft carrier. This is more pronounced with lower powered planes.
My father was a pilot and owned a cessna 150. You definitely learn about ground effect when landing! It's said that it has an effect within 1/2 of the wingspan from the ground. One trick for short field over obstacle grass runway takeoffs he would use was to wind up the engine, release the brakes, lift off the ground early long before normal rotation speed was reached, by using ground effect, then level our a foot or two above the runway, thus using ground effect, to remove the rolling resistance of the wheels to "run like hell" gaining momentum until he could "pop" it up just over the trees then level off again to gain speed back to establish normal climb rate. Bush pilot's trick. Flying is about energy management. I know of a "gotta go!" fatal plane crash of a plane from a short slush covered runway that failed to clear an obstacle because this wasn't followed. The slush slowed the acceleration and they knew this would be a factor. It's usually against policy but as soon as you are commited to the takeoff in this situation, and the plane will fly in ground effect lift up a couple feet, retract the gear to reduce drag and "run like hell!" Gradually gaining a few more feet to prevent a tail strike if needed get all the speed you can, and trade energy for required altitude, then unload the airplane to gain back climbing speed. Instead, they lied to the airplane, stayed on the runway, trying to get to normal rotation speed, failed, and then just kept hauling back on the stick, willing it to fly, gained a mabey 50 ft and stalled. "You can lie to your friends and family, but if you lie to your airplane, it will kill you!"
Try that shower thing again with cold water.
blowing on a sheet of paper has nothing to do with a airplane wing , airplanes fly because of the air pressure difference between the top and bottom of the wing and that's it , exactly how a vacuum cleaner works ,
shape , size, thickness, delta all has to do with application ,
@@cardboardboxification Starve the lizards! I have provided everyone, even you, with some easy experiments that beautifully demonstrate the theory of pressure differential and is EXACTLY what I was refering to, because the air above the sheet is travelling at a greater speed than that below, albiet at zero speed, the air pressure below the paper sheet is higher than that above the “wing” thereby lifting it skyward. Anyway that’s how it was explained in the 1960’s by a senior TAA pilot,on Channel 9 TV. He also demonstrated the blowing between 2 sheets routine. A retired Cathey Pacific flight engineer cousin of mine mentioned the shower curtain phenomenon to me last year. How else would these paper sheets react the way I’ve explained, perhaps you should try it it sometime?
It's worth noting that whilst most flaps on modern aircraft typically do two things to increase lift - extend the wing surface area by travelling rearwards somewhat to temporarily make a bigger wing, and tilting downwards to temporarily increase the camber of the wing - not all flaps do this, some types work a bit differently. There are quite a few types of flaps, including plain flaps, slotted flaps, fowler flaps and split flaps and they all have somewhat different features and work in slightly different ways, but the interesting one where discussions about what produces lift are concerned, is split flaps.
Two very famous aircraft which we all know pretty well - the Supermarine Spitfire and the Douglas DC-3 - have split flaps, whereby the bottom half of the rear wing area lowers, but the wing surface above that section does not move at all, so this arrangement neither increases the wing surface area, nor does it alter the overall camber of the wing, yet it still produces lift; it does that largely by deflecting air downwards, which in turn forces the wing upwards, i.e. it is taking advantage of the effect of Newton's Third Law of Motion - to every action, there is an equal and opposite reaction - so, no Bernoulli Effect required here at all. Split flaps create a lot of drag however, thus they are typically more helpful for landing than for taking off, where you basically want a lot of drag to slow your descent speed. They are not quite so great for take-off, because they act on the rear of the wing, so they significantly increase pitch down too. All this is why you don't really tend to see split flaps much these days.
Nevertheless, despite there being more efficient flap types than those found on the DC-3 and the Spitfire, the existence of split flaps is enough proof that there is more than just the Bernoulli Effect involved in creating the effects necessary for an aeroplane to fly around. To be fair to Neil DeGrasse Tyson, the gist of what he is saying is more or less true and probably just about good enough for people who don't really need to know everything about a subject. Really this is his oeuvre, in making layman's terms simplified explanations of stuff to people with no knowledge of a subject whatsoever. He could probably do with sorting out his terminology a bit however, for example when he refers to elevators as rear wing flaps, whilst this is kind of what they are in terms of function, it adds to the confusion a bit to use these simplified terms. It's not too hard for people to grasp things in using the correct terminology, so he should really endeavour to do that. Being someone who trains people on aircraft, I do find myself on occasion having to explain the various bits of an aeroplane when walking around them and pointing to those parts, so whilst I can appreciate that you don't want to overload people with information, giving a proper explanation and using the correct names for things is never a bad idea; people will 'get it' if you tell them things properly.
On another explainer, Tyson said that airplanes taxi in the air above the airport, and not on the ground. Chuck Nice was visibly disturbed by Tyson's explanation, because even Chuck knew that aircraft taxi on the ground….on taxi ways.
Can’t they also be referring to holding patterns and go arounds etc?
High time you all start paying real taxi's. Then everybody can go to excellent public schools and that will avoid having so many people losing contact with mother earth. Educate like everybody, like it was like centuries like ago. Like. Duh.
@@marquisdelafayette1929 Yes, and he uses exactly the WRONG word for that. Besides, that word taxi is ridiculous, anyway. Who invented that, deserves spanking on his taxi area's.
Unless you are Harrison Ford. Then you just land wherever, taxi-ways, golf courses, and so on, lol!
I think he was confusing that with holding patterns
Dunning-Kruger would be proud of their theory!
It's undefeated. Unlike Neil deGrasse Tyson.
It is an observed phenomenon, not a theory. Just to be a bit pedantic.
It's probably reaching to apply that to everyone. They only used 45 people in the study, and they were all ivy league undergrads.
I think Tyson has an idea that "smart" means he can't be wrong, and that anything that sounds reasonable to him must be right. Also that anything that confirms what he already assumes or believes must be right, and this gets extended to subjects that aren't science-related. You never really become smart without sufficient self-doubt.
@@lisadioguardi5742 David Dunning has done a large amount of related research. While that one study may seem limited, it does not stand alone.
Several years ago I was looking through a graduate level aeronautics textbook where the author was discussing lift via Bernoulli & upper/lower path length. He concluded that a Cessna 182 would have to accelerate to over 400MPH to lift its own weight if this were the mechanism that enabled a wing to generate lift. It is amazing that this myth is still being taught by the FAA and was a multiple choice answer on the airman 3rd class written test.
When taking those silly FAA written exams, I studied normally to learn the stuff, sure, but then a couple days before the test just start going through the list of all the FAA questions that they publish (do they still?) that has every question and every answer and memorizing--and there was always at least one question where the book warns "the FAA wants you to answer B even though that's wrong". Sure makes it go quicker when you recognize the question and don't have to read it and can just pick B or D or whatever without any work. I finished the instrument 3 hour test in about 25 minutes. Proctor asked "are you giving up?" "No, I'm done". 98/100. Dunno what I missed and that still haunts me.
lift is pressure differential between the top and bottom of wing and that is it , nothing more...
shape, size ,flat bottom , fully symmetrical , straight , delta ... all has to do with application , weight , speed
The problem is that as kids we were all taught about this cool effect, and it stuck with us. What we seemed to forget about is sticking our hand out of the car window at 60 mph. AoA trumps airfoil effects. A brick can fly with enough thrust and AoA.
Correct, the lower pressure above the wing is a byproduct of plane scooping the atmosphere out of the way.
This was one of the first lessons I had for my private pilot certificate.
I remember my flight instructor explaining it like Neil explained it but my ground instructor explained the way you did. I eventually convinced my flight instructor to talk to the ground instructor so they would be on the same page.
Fun times! Thanks for the video! 🙂
"Astrophysicist to the Stars" Neil deGrasse Tyson wanders into the weeds to find a rake. Steps on it.
Haha his explanation about what happens when helicopters loose power was another fo paux
🤣🤣🤣🤣
@@Iflyagrasshopper . You mean Faux Pas ? Or is a Fo Paux something else...............
😂🤣😂🤣💀
The primary purpose of an aircraft carrier's angled deck is to allow landings and launches simultaneously.
And, you know, aircraft carriers being movable and stuff means that one runway would be enough to always take off into the wind.
@@beeble2003Yeah they always turn into the wind and go high speed to make the takeoffs even possible
Even more important for landing.
Neil DeGrasse Tyson, and most others, also forget that you can build a plane with thin flat wings and it will still fly. Inefficient, yes, but I build balsa models like that for fun.
Some acrobatic airplanes have symmetrical (top-to-bottom) wings that fly upside down, just as well as they fly upright. And people sometimes fly upside down (at -1G) using wings that are optimized for upright flying.
I knew that from childhood because a paper aeroplane would fly. Many of the balsa wood toy planes from my childhood also had wings cut from a flat sheet of wood which was curved slightly by the attachment to the "fuselage". They would also fly perfectly well.
it flies because when titled upwards the air has to move a greater distance and this causes a negative pressure on top
I was also going to mention exactly this... thanks.
It is not necessarily inefficient. As we get into super and hypersonic speeds, a thin, flat wing is very much desired, aerodynamically.
Only one of those three should be recommended, and that is Doug. The only video people should watch is his. Prof Babinsky uses a simplification that has existed in the literature since the 1920's, and it only captures the flow around the leading edge. He explains none of the transient effects that are important. It is as bad as all of the others, Coanda or Bernoulli, and it equates to "just look at this one part, and ignore everything else". It is very Wizard of Oz. Prof Fidkowski make the common engineering mistakes, talking about inviscid lift and does not address some key aspects. Doug's video, his book, and his articles in The Physics Teacher are amazing. He makes it clear that to calculate lift you are solving the Reynolds-averaged Navier-Stokes. The work by Prof Tianshu Liu from WMU makes it very clear that the Navier-Stokes are needed, given viscosity is fundamental for the generation of lift. That is, the Navier-Stokes are the fluid equations we have with viscosity (unlike Euler). So, Magnar, I am sorry to say that you are also incorrect because what NASA have is incorrect. In 2D, where most of the fundamental airfoil data comes from, flow does not accelerate downwards, it returns horizontal, and you can show the lift force as a the pressure difference between the upper and lower surface on the wind tunnel, which is what NASA measured back in the 30's and 40's to characterise all the NACA airfoils. So, while Newton's 2nd law, which must include pressure and viscous forces, will show a momentum flux across an airfoil, it will not be equal to all lift. In fact, this was shown by Prandtl back in 1919.
The most important point is that lift generation is a transient effect, where by viscosity if the fluid results in a vortex being shed at the trailing edge, which due to conservation of angular momentum results in a bound vortex around the airfoil. This is what makes the flow over the top faster, and the flow under slower, this then equates to lower pressure above and higher pressure below, which is the lift force.
I dont know what you think pressure is but for sure its the air hitting the underside of the wing (actually all sides). Infact pressure measured at the surface of the wing (or any other surface) is precisely the amount of force being applied by impacts of the air molecules onto the surface (by definition). This is why, for example, pressure increases with temperature (as the air molecules have higher kinetic energy on average, and its also why we have ideas like density altitude).
So saying the pressure is higher under the wing than above the wing exactly means that more force is being applied by the impact of air molecues to the lower surface than the upper surface.
Correct, but why is the pressure is higher under the wing than above the wing?????
Airports also consider prevailing wind directions. So runways at a 30° angle may be the best if the winds almost never are at 90° from the first runway.
Yes, I'm based at an airport with runways 12-30 and 23-5 and other than when a weather front is crossing and the wind is switching direction it is pretty much always straight down one of those runways.
Your shirt is indeed cooler! More people should see this video.
As always captain, you correct misled people. Being always looking for the truth and do research is key to good pilots. Thank you for your wisdom 🙏
*misled
What really scares me is that I have never taken a single class in aerodynamics... yet I still knew many of the things he said were wrong. Particularly the part about all airports and aircraft carriers have more than one runway are they are never at 90 degrees... you know... because I have eyes.
air ports runways are laid out in the direction that the wind flows in the area ,
@@cardboardboxification and to miss the mountains regardless of airflow. and not all airfields have the luxury of two runways. I have landed on islands where a cross strip would be way too short, and for that matter the runways they did have were always bloody short.
The old abandoned santa susana ( simi valley )airport had a very small strip, the east side had hill that was cut away so exposing the runway for incoming planes.@@SuperSrjones
Neil does touch on this by pointing out that when the angle of attack changes from the pilots deflecting the tail surface with the elevator, the pressure differential over the wing changes. This only shows the internet has no chill.
I was working on my pilot licenses while in college pursuing my civil engineering degree. My hydraulics professor was the first engineer I had heard who was so perplexed at how many otherwise credible people had the flawed "understanding" of Bernoulli and lift. To this day, from the FAA publications down, that misunderstanding continues. It's hard to understand why it has not been corrected after having been explained by so many sophisticated aerodynamic experts like those Magnar refers to at the end of his video.
Yea, I was gonna say the same thing: it's hard to blame Neil about Bernoulli when he's basically saying the same thing the FAA taught me while getting my pilot certificate....
How do you explain stall without Bernoulli? “Negative pressure gradient” triggers warnings in x-foil .
@@davetime5234 This sounds like a Business Accountant speech. Going in with an engineering mind I am fascinated about how friction (drag) can from a fast flow can pump air in the boundary layer against a pressure gradient.
@@davetime5234 The Navier-Stokes equation is not consistent. And it is not real because fundamentally, atoms are particles and not a continuous fluid. There is some band aid available to get a numerical solution. Stick to typical bounding conditions. Include diffusion (thanks to the particle nature). That said, stall can be reliably predicted by xFoil even on an old PC.
@@davetime5234 “cars” don’t stall. Maybe their engine. But this is quite different from aerodynamic stall.
Neil seems to be getting careless. Air does not "want" anything. It is a group of molecules under pressure due to gravity. I assure you, air does not want anything, just as water does not "seek its own level". It is water. Water seeks nothing. Words matter, Neil. 🙂
Yes, what you describe is somewhat of a problem these days. It's not just Neil tending to anthropomorphize like that while trying to explain some aspect of Physics.
@@jokerace8227 This anthropomorphic mindset has reached insane levels in IT. Ascribing aspirations, dreams and goals to elections and transistors is a deep form of bullshit, but seems to a big part of many AI discussions. Malicious programming and programmers, perhaps, but many seem to believe that a device can have a mission, dreams and goals outside of its program and programmers.
somewhat water wants to do something. it is not completely wrong.
read my post!
Physicist do this all the time, it’s not their fault if you bone heads can‘t comprehend a metaphor
He has the difficult job of making science understandable to those who have insufficient instruction in science. The U.S. has been falling behind in that since the 80's.
Using the definition of NASA: "Lift is a *mechanical* force. It is generated by the interaction and contact of a solid body with a fluid (liquid or gas)" then, in a *strictly mechanical sense* only the lower part of the wing is able to generate lift in steady horizontal flight.
By definition, no force is able to get a "grip" on the upper part of the wing (the outside surface which is in contact with surrounding air) and *pull* the upper part of the wing upwards. There is no pulling force on the upper part of the wing. However, because of the angle of attack and the fact that the wing is not moving through a vaccum but through pressurized air, the upper part of the wing is able to decrease the ambient static air pressure exercised by Earth's atmosphere, therefore less air molecules are hitting against the upper side of the wing pushing it downwards, but this is not lift as lift would be directed upward, not downward. So at all times, air is only pushing against the upper part of the wing pushing the wing down and that's why those diagrams here: 8:56 are wrong as they depict force vectors pulling the upper side of the wing upwards.
There is no mechanical force pulling the upper part of the wing upwards. However, there is a force resulting from static air pressure pushing at all times against the upper AND lower part of the wing. So the lower part of the wing is able to push the wing upwards as the upper side of the wing it is no longer pushed down as much because of aerodynamic effects (angle of attack, wing shape, air speed and so on). The wing moves upwards because of the aerodynamically created influence on the effect the surrounding static air pressure has on the wing (greater on the lower part) + the aerodynamically generated force of lift on the lower part. On the upper part, there cannot be any aerodynamically generated force of lift, only an *aerodynamically generated local reduction of the effect of static air pressure pushing downwards against the wing* (because of Bernoulli) therefore diminishing the downward push of the static pressure on the upper part of the wing. Therefore not every surface on the wing produces lift, but every bit of the surface influences how air moves around the wing and how the airflow is bend.
Also, in case you don't understand this argument: if you buy a vaccum suction cup holder, once installed on a window pane, it actually does not suck on the window to stay put. The part facing the window pane can be compared to the upper wing, the part facing you can be compared to the lower wing.
So the "vaccum suction cup holder" remains put because static air pushes it against the window pane (that would be lift) the only difference is, in order to create it, there is no need for airflow because the surface facing the window is hermetically sealed of and the lower static pressure is permanently maintained so there is no need for dynamic airflow over a curved surface at an angle of attack in order to create a local reduction of static air pressure hitting the wing.
Now, it would be foolish to say the inner part of that suction cup holder created "more lift than the outer part" - as no force is pulling the inner surface against the window pane, only the outside static air pressure is pushing the suction cup against it.
TLDR, but yes. Magnar qent wrong at 8:20.
You are absolutely right!
It's a matter of semantics whether you want to think of it as suction or not. It's a pressure differential. When you turn on your vacuum cleaner does it "suck" up the dirt on the floor or is it the wind, caused by the air trying to equalize the pressure differential, that is "blowing" the dirt into the hose? Most people are going to think of it as suction.
Ive made planes with flat pieces of balsa for wings and they still fly. You don’t need the tear drop wing profile for low and high pressure. The high pressure will create on the low side by simply tilting the wing angle of attack (flat piece of balsa) at a steeper angle.
Tear drop is for fuselage to reduce drag. I once got a balsa plane and am still mad that they did not machine it the slightest. So difficult to sand the edge down.
I had this discussion about "lift" with my CFI, so I do not claim to know everything but I have a pretty good grasp on what's going on.
Bernoulli's principle definitely applies buts its SECONDARY to a much greater effect, that would be Newtons 3rd Law of Motion which states "For every action there is an equal and opposite reaction".
Now as you increase lift you therefore increase drag, you can see this in action during a turn where you get adverse yaw. In regards to lift, as the air hits the wing at whatever angle on the underside you get downward deflection which causes drag, well the equal and opposite reaction is LIFT which pushes the wing up in conjunction with Bernoulli's Principle and that is in very basic terms how a wing works. Once you exceed the CAOA (Critical Angle Of Attack) the wing is no longer producing lift, so that would be the stopping point of lift generation in flight, on the ground you need sufficient airflow to generate lift, when not generating enough airflow under the wing on the ground you stay grounded.
For those of you saying "So what you are saying is, if I went fast enough or the wind was strong enough I could fly?"... technically yes, I mean a Tornado can certainly give you enough airflow to offset your weight and drag.
Great video explaining most important aspects
There is one other thing Coranda effect . The tendency of a fluid to stay attached to a convex surface
Coanda Effect (as beloved of the Dyson company).
as a kid in elementary school, one day an airline pilot came to the school to teach the class about how planes work. She used the equal transit time explanation to show how lift works, and unfortunately by the time I had learned that that wasn't entirely accurate, I had already been sharing that incorrect information for years.
Finally! someone else who knows about the Babinski principle.
regardless of if the flows come together at the same time or not, the top flow moves faster and thus drops the pressure and lift created. Compressibility of the air was left out for whatever reason, but it works, every time I take off. Nitpickers will be nitpicking, just let me fly.
Tyson is one of those people who, while obviously very knowledgeable about many things, is also full of hubris and seems to want to always be the smartest guy in the room. I've known several people like him - smart but overly confident about what he actually knows.
If Bernuoulli effect is dominant in producing lift, then upside down flight would be impossible.
no, Bernoulli always plays part when air velocities are different on both sides of the airfoil, you always can calculate lift knowing the distribution of velocities, upside down has nothing to do with it
The wing doesn't know it's upside down
You mean if the equal transit time hypothesis explained lift, then upside-down flight would be impossible.
Thank you for your clarification on this issue. Good Job.
Tyson is a science _popularizer,_ just like Carl Sagan was. Nothing more.
Carl backed his talk with something more than Neil does.
Except too much of what he spouts is NOT science, so in reality, he's a pseudoscience populariser.
He's never appealed to me, maybe it was his self-assured smuggness which is not a great characteristic of a scientist.
feel like hes trying to dumb it down compacting the whole thing trying to relate, but it makes it only more exhausting and even wrong. If he wants to communicate it, maybe he should make animation or practical demostration, but he sits there trying to convey. Also taking his sweet a time with it
Thank you Captain for a great explanation. I was taught the wrong way and no explanation was ever given as to how an air particle going across the top "knows" it must meet it's slower moving buddy at the rear of the wing at the same time. We were also never taught exactly WHY and HOW the airfoil curve causes faster airflow along the top. Your explanation and the NASA site at last clear it all up. NDGTs best move now would be to own the mistake and make a new video.
Aïe !!! at 9:05, green AND blue are low pressure.
Above AND below wings, there is LOW pressure. The deficit of pressure above is more important than the deficit below, so the summation gives lift.
On the diagram at 9:05, green AND blue are low pressure (don't look at the arrows). The size of green (above) is bigger than the size of blue, so there is lift.
I recently saw him talk about landing the space shuttle. He claimed that NASA discovered that putting linear grooves in the runway would straighten out the shuttle when it landed. The Dept. of Transportation had been putting grooves in the highways and freeways before NASA even existed. They do this to help the road shed water when it rains to avoid hydroplaning. I've driven on these surfaces for almost 50 years and I can tell you that a grooved surface does NOTHING to keep a vehicle going straight.
A grooved road surface and ribbed tires make for a squirrelly motorcycle ride!😬
I suppose then he thinks they are "self driving roads" just set your cruise control, let go of the wheel and begin watching Tyson DeGrasse vids for a few miles, no worries mate! Grooves would help tires skidding sideways in a crosswind to some degree essentially "steering" it. The shuttle landed at a high angle of attack and spent a long time with the main gear on the runway holding the nose up, letting it settle slowly. The load on the mains is very low for a while because of ground effect and the high angle of attack. every time the pilot inputs a rudder command to keep the shuttle straight in a crosswind, it causes a sideways force on the main gear trying to rotate the nose in the opposite direction. This is because they can't bank it to counter it while the wheels are on the ground. Applying the rudder without banking when flying is called "skidding" you do this to point your nose more into a crosswind to fly a straight course, using a portion of your thrust to counter the crosswind. This creates drag. In a small, slow, plane and a large crosswind, I have actually flown a course forwards by looking out the side window! That's fun when using a compass to navigate since you have to make a correction because the plane rotated under the dial. You are doing the same thing in a plane in a crosswind landing, you are "drifting" the aircraft. You can also use the engine to pull you back over the runway. The shuttle is a glider, this means they can't go around, and can't power it back over the runway if things get out of hand. It's actually an amazing piece of flying to make an "engine out" landing every time! The sooner you stop the skid the better because when the mains finally "bite" at a high angle to your line of travel they throw you to the side, and you can begin fishtailing.
To accomplish this the grooves run DOWN the runway or road. They do help with skidding. Concrete is very smooth, therefore hydroplaning is more of an issue because water has a harder time getting out from under your tires. Groves help with this especially cross grooves.
Thanks for confirming that this comment section is just unearned NDT hate. The grooves WERE invented by NASA in the 1960s for the space shuttle:
"NASA developed grooved runways in the 1960s to improve traction and reduce hydroplaning for aircraft landing. The technique involves cutting grooves into concrete surfaces with diamond blades to help water run off, similar to how tire tread patterns increase traction. NASA engineers discovered that grooved runways could significantly reduce accidents. The Kennedy Space Center's landing strip was safety grooved for the Space Shuttle, and the technique was later applied to highways, stairways, sidewalks, parking lots, and other surfaces."
NDT needs to turn off his ego and watch this vid.
It has no OFF switch.
The character Sheldon Cooper on the Big Bang Theory is smarter than Neil.
All the characters on Big Bang Theory are smarter than Neil. So are most of the actors.
Ok, so, there is a temporary climb generated by excess lift. However, I'm going to say that airplanes' rate of climb depends on their excess power, and their angle of climb depends on excess thrust. Airplanes fly because of lift, but they climb because of excess power and thrust. Gliders climb due to thermals, which is an external source of energy. Rockets climb because of excess thrust.
The decrease in pressure above the wing at sea level is more pronounced than the increase in pressure below the wing. But, if you consider an aircraft like an SR-71, in the near vacuum of high altitude, there is almost no atmospheric pressure to remove from above the wing. Therefore, the aircraft resists gravity only due to the upward force of the pressure beneath the aircraft. All aircraft fly because of that same reason.
Magnar, lift has less to do with de pressure difference on the surfaces on the wing than we think it does. Take a spoon, turn on the kitchen water faucet and put the concave part of the spoon into the water stream. The spoon will get pulled into the water stream at a aproximative 90 degree angle (lift), even tho there is no water flowing on the convex part to make a pressure difference. Lift is a 90% upper wing surphace phenomenon.
I had not listened ot Tyson's explanation previously, but it sounds like a simplified Physics class that ignores the complications of the real world. It reminded me of the joke told to me by one of my Physics professors in college to stress that point: "Physics is the study of frictionless elephants whose mass can be neglected". The forces on the air do indeed act to "keep it at one parcel", but real-world forces like friction and the energy imparted as the wing moves through it prevent this from happening. Terms get complicated depending on the frame of reference that is being used (ie. whether the wing acts on the air, is with an aircraft, or the air acts on the wing, as in a wind tunnel).
At least Tyson discussed angle of attack and its effect on lift. Some drawings used to explain lift show the airfoil at an angle of attack that produces either no lift or sometimes even a net downward "lift".
Tyson is perhaps the most annoying explainer on RUclips and I am not alone in my observation
You do NOT talk about daddy Tyson like that. What is wrooOONG WITH YOUUU???
Wel, holding your hand out of your car window is still a good analogy for a wing. A poorly designed wing but a wing none the less. You do not need an airfoil shape to achieve flight. A cinder block will fly and be controlled with enough thrust. The airfoil shape is more efficient at creating this effect of being sucked up like a noodle by the lower pressure air as this air is sucked down into the upper shape or surface of the airfoil. It's bernulis principle. It's a half Venturi shape layed on a flat surface instead of bent into a circle. A ram air engine of sorts. Sucks its way up and pushes that air downward. It's some wormhole stuff.
A cube can fly, just vector the thrust to apply all of the lift. Nobody cares about flying, everybody cares about flying with thrust that is much smaller than your weight.
Such a great video, even pilots often get this wrong, since I guess it's just easier to teach an oversimplified explanation to someone who won't ever actually have to design a wing, but great to see a pilot who really gets it!!!
The atmosphere is a closed system. Introduce an object into it and the air is displaced. The air has to go somewhere. Interject a wing form, give it speed and air has to go around it. Some goes faster that the other and a low pressure is created and the void displaced. The wing moves to the area of less pressure. The wing lifts.
The best explanation I’ve seen is lift is the force generated by the difference in pressure between the upper and lower surfaces of the aircraft.
Neil will always be a space cadet. Best description of lift I have seen yet. Never thought of it as a hybrid principle between Bernoulli and Newton.
Honestly, as a huge fan of Carl Sagan, Neil deGrasse Tyson is regular disappointment.
He states the air just "wants to" reach the same air particle on the other side - but doesn't question by which mechanic this air particle can do this. Thank you Magnar for being a great teacher.
So what happens in upside down flight?
yes it is harder to increase preassure under the wing than lower the preasure over the wing but it doesn't mean that Tyson is wrong, lift is generated by air hitting bottom of the wing, preasure is molecules of air hitting surface, there will be no lift without high preasure under the wing
The part that's wrong is the claim that the packet of air splits up at the lading edge and then recombines at the trailing edge.
And this is why he needs to stay in his lane. My home airport of Plant City Municipal Airport(KPCM) only has one strip and 2 runways. There are airports that can have 2 strips and only 3 runway, not 4 like you would think, because one end is not used for takeoff or landing due to obstacles(but usually due to rich people). Also, where I used to work at Igor Sikorsky Memorial Airport(KBDR) has 2 strips and 4 runways(used to have 3 strips and 6 runways), and the two remaining strips are RWY 6-24 and RWY 11-29.
KCPM is 10-28 right?
Neither of you are correct, even your video contradicts your statements. Freeze the screen at 4:31 and take a thorough look at it. It was not the air above the wing that became faster (see the uppermost smoke line at the very top of the screen matching the one right above the wing), but the air below the wing has slowed down due to the pitched position of the wing. In this specific experiment the pitched position of the wing was a more substantial factor than the wing profile. You can fly even with a completely flat shaped wing if it is pitched as it will create a pressure delta on its own.
Ha! You spotted that too. Check my comment earlier today.
Insightful point. The author of the video could have easily just shown the case where the wing was level but he didn’t. Why not? I’m suspicious that it would have shown the two airstreams arriving at the Sam time.
As a sailing instructor I sometimes had students who knew all about Benoulli's theorem. When I pointed out that a sailboat's sail has no thickness, I was met with disbelief. "How dare you question Benoulli!"
Newton's law of motion explain airfoil lift nicely. Those infatuated with Benoulli have to resort to Newton when challenged on the inconsistencies.
You are100% correct to question the use of Bernoulli's theorem in sailing. But whose explanation do you use? Marchaj? Gentry? Fossati?, North Sails? ...?
Coandă effect
There are many principles at play with an airfoil.
Newtonian physics is the ultimate explanation, because lift or any aerodynamic force is due to an equal and opposite reaction to an air mass being accelerated. Air mass is accelerated (deflected) Either by a moving surface at an inclined angle of attack, or by another deflected surface attached to a primary surface which is moving at zero angle to the relative wind.
The how and the why of this air bending is explained by Bernoulli, Coandă, et. al.
@@RationalDiscourse As I said, an angle of attack deflects the airstream in one direction which results in the equal and opposite force in the other direction. Newton.
@@Triple_J.1 Without an angle of attack there can be no lift. Your "zero angel to the relative wind" idea is not correct. If the airfoil is producing lift, it has an angle of attack. The fact that the bottom edge of an airfoil is parallel to the wind direction does not mean that the airfoil has a zero angle of attack. Tha angle is defined by the cord of the angle of the two sufaces of the airfoil have at its trailing edge which results in a downward deflection of the airstream.
@@davetime5234 I am not imposing such a condition. One side of the sail developes higher pressure because it is pushing the airstream in a new direction. On the other side of the sail the airstream wants to continue its direction according to Newton's laws of motion. However, that continuation results in a vacuum because the sail curves away from the direction of the airstream. That lower pressure induces the airsteam to change its direction and follow the curvature of the sail. Newton's laws are all that one needs to explain why a sail devlops lift.
Sir, you are the one who is imposing conditions with your "contoured airflow" hypothesis. Bernoulli is NOT "essential" for explaining lift.
Airport runways are oriented to the prevailing winds at their location. A wind rose helps illustrate prevailing winds, and it can be informative to compare a location's wind rose with its airport runway(s). The runways are most likely NOT 90° to each other (though it can happen).
Finally, a sufficiently concise video on lift. I took a super intriguing online aeronautics course with TU Delft, and got quite annoyed when I had to take an intro physics class in college. Bernoulli is an insufficient explanation of lift; I prefer to talk about the Newtonian aspect, angle of attack, and drag.
Edit to add: the aeronautics course was taken through EdX
Neil DeGrasse Tyson gets many things wrong outside of his own field of expertise. A typical example of the Dunning-Kruger effect.
He even gets many things wrong when it comes to basic physics and astronomy.
Unless you call his area of expertise hype and self promotion.
You should have stopped after "wrong".
It gets things wrong about biology too.
@@av_oid Biology, medicine, history. Even basic physics and astronomy.
Neil's field of expertise would be hype and self promotion.
Can you show me where he got basic physics wrong @@HopDavid
It is interesting that two of the world's leading astrophysicists, Tyson and Kraus, rockstars of their field, think they can bang on about everything. I especially dislike their hubris, the emphatic way they pronounce their opinions. A real scientist is careful and uncertain - because science is a set of hypotheses which are only correct until we find something better. In consequence, I have no time for such people - because if they are wrong about a subject I do understand, they might well be wrong about everything.
It is a stretch to call Tyson an astrophysicist, much less one of the world's leading astrophysicists.
His C.V. is easy to find online. Five 1st author papers, all from the 80s and 90s. In 2008 his name appears very late in long lists of authors for the COSMOS review papers.
Were those five 1st author papers during his college years outstanding? No. Harvard turned him down for post grad. At University of Texas they dissolved his doctoral committee, essentially flunking him. His advisors correctly told him he had no aptitude for astrophysics.
Most of Tyson's career has been flashy and often inaccurate pop science.
Nobody is omniscient but that doesn’t make them wrong about everything. Tyson gets people interested in science and we need a hell of a lot more people like him because way too many people treat science like another religion these days. You take what knowledge you can from people but verify what you’re being told and don’t just blindly trust the cult of personality. On the flip side, whenever a smart guy gets something wrong, there’ll be a long line of people gleefully piling on to stroke their own ego.
@@Danimalpm1 Does Tyson inspire a deep interest? If so why is it his fans usually don't notice his errors?
His bad math and science is merely annoying. I do not care if he tells his pseudo nerd fans that there are more transcendental numbers than irrationals. Or that the James Webb Space Telescope is parked at the sun-earth-l2 point in earth's shadow.
What makes me angry is when he uses his wrong history to underscore his talking points regarding politics and history. Using falsehoods to push a narrative is a serious offense,
@@HopDavid Snake in DeGrasse Tyson is an establishment guy. Science is what the government _tells_ him it is: he re-packages their politics, dressing them up as science and then spews propaganda on behalf of Big Pharma and the ICC.
@@Danimalpm1yep, and they're making themselves known with their vitriol and hysteria.
Thank you for this wonderful explanation
8:51 it’s meant to be drag, but in the wind tunnel experiment earlier the angle of attack of the wing was not flat. i always think it seems like a lot of it is the change of angle of the air rather than pressure change
As a paraglider (ridge soaring) we use the air flow over hills to gain lift. It's quite odd, because it's been described to me as being the same thing that happens in the first 1/3 of a wing chord. However the "upward" deflection of the airflow over the mountain creates a much high band of lift just in front of the summit. The upwards vector of the air there can extend hundreds of feet above the hill, even without any thermic effects.
The danger is what happens on the "back side" of the hill. Being there in a paraglider would be no less dangerous than going through a river rapids in a childs blow up dingy. You can't see air. However you can visualise it as water. The front side of the hill has an accelerating laminar flow. The back side is tumbling crashing waves of down draughts and the resulting rotors. When I asked my instructor, "So how bad is it if you got blown over the back?". His answer was short. "Back breaking."
Flat top mountains are a lot more fun. As long as you don't go too far back, you can land in the laminar zone, so it's really smooth.
Runway directions are chosen by monitoring wind conditions for a period before aerodrome construction which @gcpgrey did a video on. They aren't at 90 due to laziness . Nzch has it because wind commonly goes north south (02/20) but occasionally off the mountains (27/11).but klas doesn't have 90 diff. This is because analysis shows common wind directions.
Right. Ideally, the runways will be situated so that most of the time, one will be aligned with the wind. If the wind is mostly from a narrow range of the compass, they might build runways that cross at a narrow angle. Although a lot of airports have to contend with geographic constraints and can't have ideal runways. The busiest airports have parallel runways with no crossings because that's the best way to serve many planes in quick succession. Modern transport category aircraft can handle huge crosswind components, so they don't always have to perfectly align with the wind.
@@bbgun061 and unfortunately it sounded like mr nordal was saying they're always 90 which I don't think is right either. Although what's kden about :p
@@mickster04 Denver (KDEN) is what you get with almost unlimited land to build on lol...
@@mickster04 No, he doesn't say they're always at 90. He just says that putting them at 90 is the best solution if you want to be best able to cope with every wind direction. (And the runways at KDEN are at 90 degrees to each other.)
@@beeble2003 my mistake!
Who even takes Tyson seriously?
As an engineer, I think you are splitting hairs to debunk NDGT. He is trying to educate a lay audience at a level that a non scientific audience can grasp. And he does that extremely well.
If you want to argue with his science, look for the papers he writes, critic them with other scientists.
I took aviation mechanics in the late 80s and what Mr Tyson stated was exactly what was taught. The instructor even used dots to show the path taken by the air flow and the dots aways met up. Its been decades but I can remember plotting airfoils using stick pins and string.
My instructor was a licensed pilot with the following ratings; instrumentation, multi-engine, instructor and was a licensed A/P mechanic. He never stated how many, but he spoke about the times he assisted in a crash investigation and a local kit plane producer in addressing undesired flight characteristics.
Neither pilots nor mechanics need to understand the physics of flight. They are practical disciplines. As a physicist, NdGT ought to be able to look deeper into the matter, but that doesn't seem to be his objective. He has become an entertainer, not an educator.
@@GH-oi2jf He's a planetarium director, not a research scientist. I'm not sure it's really accurate to call him an astrophysicist.
Thanks for clearly explaining how he is wrong. Neil has his finger in every aspect of science, philosophy, etc. He's full of himself and he really believes he knows about everything in this universe.
Arrogance and ignorance are never far apart.
It's actually a little bizarre that NDT got this so wrong. I mean if he thought for a moment and recalled - for example - that many airplanes regularly fly inverted (and that most airfoils don't look like his example and many are close to symmetrical about the chord line) he'd have to realize that his explanation was flawed. And don't even get me started by the "up the flaps on the tail wing" part. Sigh. Thanks for the video Magnar!
I watch occasionally videos from NDT. Sometimes I don't have enough knowledge of the topic to call him false but this time about airplanes and airport configurations he hit right at one of my best topic. He was pathetic the less I can say.
- NDT "Airplane must always take off facing the wind" FALSE
- NDT "pilote raise the tail flaps to raise the nose up" WRONG it's aileron. There's no flaps there and flaps on wings have a complete opposite purpose
- NDT "Airports always have two runways and are never in a 90° cross over to give more possibilities of taking off up wind" FALSE and FALSE
- NDT "When the plane accelerate it comes a momentum where the plane pop up suddenly to the sky. It's not something happening smoothly and progressively" FALSE bullshit
and of course the Bernoulli explanation...
Like someone else wrote here, if NDT can be so wrong about a topic I perfectly know, how much bullshit he can say on topics I don't know enough to call bullshit?
@@laurentsamson8927 You claim he said that airpcraft must always take off into the wind. FALSE. He says that, _given the choice,_ they would take off into the wind. As for the "tail flaps" thing, sure, but he just doesn't know the right word. That's not the same thing as failing to understand the concept.
I know it's going to be a good day when I start with The Grass getting disproven.
Before watching the video. Lift has to do with air mass and the speed of travel. You create a vacuum area on a wing which makes it move into the void. Which isn't a void but less atmospheric pressure
??
I learned a lot about lift from making balsa aircraft. When the velocity of the air is low and the mass of the wing is low, it's very strange how a wing responds in your hand. It defies intuition. On the other hand, aircraft can fly upside-down, making it clear that there is more than one way to generate lift from a wing.
read my post!
The sound of Neil’s voice close to the wing is enough to create lift.
Neil is one of those giant heads who claim to know more than he actually does. I was a fan of his for a short time until I realized he’s not as smart and knowledgeable as he thinks he is.
Neil is a celebrity not scientist...
The logic of building two runways on an aircraft carrier so that one of them is always facing into the wind is amusing. Why wouldn't the captain tell the guy at the helm to turn into the wind. Imagine that conversation.
Captain: OK, turn into the wind.
Guy at the wheel: We can't Captain, we didn't build that runway.
I can't wait for his dissertation on rudder theory.
I want to beat my head into the fireplace hearth hearing him explain this very incorrect thought.
Seriously, where did he even get that from? The angles are only 14 degrees or so off one another. So that’s not giving you many options to “always” have a runway pointed toward the wind.
And the super know it all tone in his voice when being so wrong! My forehead needs a bandaid.
So it’s complicated and lift is complimentary 🎉
Neil was trying to make it too basic. But the idea is correct, the displacement of air downwards by increasing the AoA is a key part of lift, assisted by the lower pressure on the upper surface
It's not making it basic that's the problem. It's telling the unnecessary falsehood that air packets meet up again at the back of the wing. If he'd just said that the air goes faster over the top, so the pressure is lower, that would be acceptable as an explanation. But he gives a completely bogus explanation about _why_ that happens.
Tyson also said that helicopters fly by creating downward thrust! 🤣 The man is almost as big a hack as Bill Nye
Is this wrong?: "also said that helicopters fly by creating downward thrust"
@@davetime5234 Yes it is. A helicopter is a 'rotary wing aircraft'. Downwash from the rotor blades is a [wasteful] byproduct that - to a casual observer - could be mistaken for "thrust" (think about this: if rotor blades were literally producing only downward thrust to generate lift, no one would ever be able stand under a hovering helicopter as the downward force produced would exceed the weight of the helicopter for it to fly). Helicopter rotor blades are in fact, 'wings' with a very narrow chord, and produce lift in the same manner as a fixed wing aircraft, the difference being that the wings (rotor blades) of a helicopter travel along a circular path to create lift, rather than a linear path like airplanes.
@@FailedTheTuringTest I'm not sure if I understood what you're trying to say:
"if rotor blades were literally producing only downward thrust to generate lift, no one would ever be able stand under a hovering helicopter as the downward force produced would exceed the weight of the helicopter for it to fly"
The force under a hovering helicopter is enormous. The downward change in momentum of air must equal the weight of the helicopter. I once stood near large heavy steel barrels that were thrown down by a helicopter's down wash.
Also, a turbo fan engine, or a turboprop blade, or a piston engine propeller on a C152. We call the force in all such cases "thrust". A helicopter blade is no different.
I love Neil's enthusiasm, even when he misses the mark a bit.
I've seen many experienced pilots and others describe the equal transit time theory. Starting in jr high school when I did a science project on Bernouli's principle. The upper wing actually forms a venturi between the wing upper surface and the air above. But not all wings are flat on the bottom and curved on top. Some are nearly symmetrical. Such as the laminar flow airfoil on the P-51.
Agree with most of the other posters however the statement about all airports having two runways is correct. For instance at our home grass strip has a single strip of land runway 9 and runway 27 which you would announce to other aircraft so they know which way you are taking off or landing.
Ok, you're obviously correct in all you said, you are discussing this from a professional airline pilot view, which is fine, Neil Tyson is not a pilot and his videos are more of the informal kind I guess. He tried to explain things in a simplistic way and by making a lot of assumptions on things he probably doesn't know that well. I think he did ok-ish, maybe he could be prepared a bit more on subjects he speaks about, but if he makes someone else read about those subjects or look them up, or cause a reaction video from an actual pilot, that's still a win I think. Sometimes, people will look for super accurate explanations, sometimes they just want a not too accurate and relaxed summary. Thanks for the video. :-)
Simplifying is fine, but NdGT's explanations are just wrong.
Simplifying would be saying that the air on top of the wing goes faster, so is at lower pressure. But claiming that the air goes faster because packets of air that get split by the leading edge of the wing have to meet up again at the trailing edge is just wrong, in exactly the same way that claiming that planes fly because invisible pixies push up on the bottom of the wings is wrong.
His claims that two airport runways should be at 30 degrees to maximise the possibility of taking off into the wind is false in the same way that "2+2=3" is wrong. (Putting them at 30 degrees means you might have to take off at 75 degrees to the wind; putting them at 90 degrees means you'll never have to take off at more than 45 degrees.) His claims that most airport runways are at 30 degrees is trivially disproven by looking at a map. He lives in New York: JFK and LaGuardia have runways at 90 degrees and Newark's main two runways are parallel and the third is at 70 degrees to them.
His claim that aircraft carriers have two runways to allow take-off into the wind is flat-out wrong, and obviously so, since aircraft carriers can move, so can always be pointed into the wind.