Amazing. It was a real pleasure to see this update, as I was not aware of it (I was looking for an old Albion's AMA video). I have been following his work since late 2011 and I am fully aware of his progressive findings, and the way this update is outlined it just simply marvelous. Way to go, Al!!!
Great talk. Washout has always been a positive part of the wings that I have built and flown over the years. Your explanation on modifying the span wise distribution of lift to promote pro-verse yaw and moving the tip rotor slightly inboard of the tips on your wing design is a brilliant solution.
Thanks guys!! Love me a good wing plane!!! My first plane I built over 15 years ago was a Zagi XT wing. I spent over 5 months building it, sanding the leading edge of the wing, making sure I used the same amount of tape, and glue, to get it perfectly balanced. I know, it should not have taken that long to build, but I wanted it to be perfect. I still have the Zagi wing, and still fly it occasionally, but not often, because I don't want to lose it. Thank you guys for all your hard work, you make it possible for us modelers, to have fun enjoying the hobby. I always wanted to be a astronaut or just work for NASA. That dream, just wasn't in the cards for me, but that doesn't stop me from being a space ranger, right here on the ground !
Amazing lecture. It’s a wonderful supplement to my aerodynamics courses for my aerospace engineering degree. I hope to one day work with people like Al Bowers
I am sooo amazed! I will try to model such a plane in CAD with the additional resources i found in the comments. It would be sooo exciting to build a model and show it to all my glider pilot friends! This is the most inspirering video i have watched in the last year!
your work your presentation is a real inspiration. I do not know if I am more impressed by the story starting from Prandtl or by the end result of the design.
That's because the AMA is full of Aging narcissist and reprobates.. The gas flying clubs are a great thing because they can stay down there and then the family has time away from all that narcissistic mannerisms it gives them times of relief ..
Really amazing lecture, even for the 'uneducated' like me. In my mind birds are doing vortice unscrewing. Perhaps fine wingspan pressure sensing plus wing section morphing going to be the future
Blanik L-13 that is very old CzechoSlovakian glider made out of the sheet metal :D I have been flying on that machine too :D It is one of the most iconic gliders of 90s. Great to hear that glider made in my country has been widely unsed by the mighty NASA and US Air Force.
I'm glad to say I use to fly L-13's when I was about 14. The USAF academy I believe flies L-23's, not 13's. And most L-13's have been grounded for a while due to an airworthiness directive pertaining to the wings root spar attachments.
There is insufficient static air pressure at high altitude to provide a pressure differential to support an airplane with high wing loading (many jet fighters). Bernoulli is an inadequate model for wing lift. The reaction model - lift is the reaction to the change in direction of the flow caused by the wing - works. Indeed it works in turbines, axial compressors with reaction blades. Horton vs Prandtl. Hortens interest in washout was positive pitching moment necessary for longitudinal stability of a flying wing. Prandtl interest was efficiency. So Bower right, they were talking about different things. Extrapolating avian “technology” to airplanes is interesting exercise if this kept in mind: birds are the original fly by wire relaxed static stability fliers.
I think Alexandre de Saint Exupery was one of the pilots who started flying rescue flights on mountain slopes in the Alps. He studied birds before doing so. He died on a mission over the Mediterranean Sea during WW2. I may have a nice solution for wing tip control, I mean with reduced drag.
Mark 18:10 Birds do active controlled stability that men made planes do not. By vectoring their only tail fin, birds can generate pitch and yaw forces.
Yes, many birds do use their tail to generate forces, but with something like a gliding albatross their tail is so small and close that it has virtually no effect on turning, because they don't need agility.
Kevin Shen I agree, particularly on glide mode. Shorten right wind to yaw right and varies wind span to pitch up or down, unlike in dive mode when food is in line of sight, on that case tail steering is more effective.
The talk is 6 years old I guess... wee they smaller also 6 years ago? your comment is just 1 year old, and maybe they got further developed and got smaller in the meantime.
@@klausbrinck2137 ooh yeah, they've been making digital transducers for many years at this point. It's a tremendously small industry though so I don't blame anyone for not knowing about them
From Videler's Avian Flight: "Boel (1929) refers to experiments by C. Richet whose pigeons were capable of apparently normal flight with all secondary, tertiary, and 3-4 proximal primaries removed." Several other experiments cited draw similar conclusions, including one where the secondary coverts were removed as well. How is this possible if the outermost primaries function as winglets, rather than lift generators?
Hi, 1. at 20.30 Al Bowers says there are 8 new planes that have used the lift curve the espouses. Does anyone know what these 8 aircraft are? 2. I understand there are 2 solutions, span constrained and span unlimited. Has anyone thought of following the span unlimited route and then reducing it to fit the constraint on span. Would all the good effects be lost? 3. As I understand it, if you can get the upwash to such a degree that the lift vector 'points forward' then you get thrust / proverse yaw. Does this require a constantly swept back wing, i.e. swpet back from root to tip? If you look at the planform of a bird the inner section has a bit of sweep back and a bit of sweep forward, which can be approximated to a straight section. It is only the outer sections of a birds wing that is swept back. So, does this mean we should construct flying wings with a straight constant chord center section, with a zero pitching moment airfoil, and with swept back outer section which have appreciable washout?
What I don't understand is the leap from taking a vertical winglet and"laying it flat", how is it a winglet if its laid flat in terms of how winglets work? I'd also love to know more about the relationship of winglets to washout because if you lay a winglet down to horizontal as is suggested here your washout affects the AOA of that winglet not so? I get the effect of a raked wing tip as seen on modern airliners but again with wing flex these are almost vertical and thus effective in producing thrust and improving efficiency but Al's wings are rigid and the horizontal tip is just that, a wingtip or extension of the wing how is that in any way a winglet? Another thing that puzzles me on flying wing theory is the idea of setting incidence, in reference to what? How do you attain an incidence with no fuselage or stab to determine airflow angle? If its just a wing its incidence is determined purely by pitch and can't be fixed or set at a predetermined angle because there is nothing to determine relative airflow angle against?
You only get "Proverse Yaw" from the increase in lift due to the control surfaces...but there is a "Thrust" component instead of an induced drag component due to the heavy washout of a Prandtl wing. This then means you can eliminate an empennage altogether and use Elevon mixing. Saves drag and Weight
Is someone able to help with this; I understand what they have done, but one part confuses me slightly which is the upwash after the wing at the tips. In my head I had thought of lift essentially being equal to downwash, if you accelerate a mass of air downwards you feel and equal and opposite force upwards (lift), so I assumed that any upwash created in the wake would be creating negative lift? But from reading the research paper the wing produces lift along its span, anyone know a bit more about this? Thanks.
@@hubmonster5559 drag acts in the direction of the airflow whereas lift, acts perpendicular to the free stream airflow. ‘Negative lift’ would act downwards whereas drag acts to the rear of the aircraft.
Lots of talk about birds and learning from how they do it. And of course, birds don't have a vertical fin. There IS one, flying creature that did have a vertical fin but that fin was on it's head. Yes, the Pterodactyl. Many years ago, a scale model of such a creature was built. It was a glider and was towed up to altitude. The vertical fin up front proved to be very effective. Now the question is, why did the prehistoric creature need a vertical fin and birds don't? I suspect the answer lies in the fact that the bird has a horizontal stabilizer that can be tilted vertically and act as fin as needed, virtually instantly. I've seen them do this. The pterodactyl had a very poor horizontal surface that was made even more inefficient due to its legs being part of the structure. Hence the need for a vertical fin upfront. What the engineers don't seem to be aware of as it pertains to birds, is that they feel their airplane directly, as they fly. RC Modelers need to fly by sight alone. If you fly from inside the airplane, you have some feedback by way of the seat of your pants, as they say. But a bird feels his plane, his entire body, not just by the seat of the pants, so to speak. And the feedback is instant and it's reaction is instant. Imagine if you could do as they portray in the movie, Avatar. Transpose yourself into the body of say, a hawk, eagle, even a pigeon, you name it. What might we learn from that experience? You would learn that you can change virtually any aspect of your machine instantly. Angle of attack. Pitch and roll. Sweepback. Dihedral. Thickness of the airfoil. The feathers themselves provide feedback along the entire span of the wing. Heck a bird can fold it's wings back and make it disappear as with when they dive for their prey. In a flash, they become a ballistic missile,,, almost. But with the advent of drones, including man carrying versions, all of this wonderful flying on a wing may become obsolete. And if ever ant-gravity machines become a reality, well, that would change everything. I'd bet though, there would still be builders and flyers of these things that we're all so fascinated with.
"I'd bet though, there would still be builders and flyers of these things that we're all so fascinated with." that is the best closing line that you could have chosen! Thanks!
You're missing the science here, the albatross he keeps referring to has no usable vertical stabilizer and only a very small horizontal stab proportionately speaking and is as such a flying wing - as for the pterodactyl I keep bringing up when I hear folks say "a scale model was built" that its not possible to build a scale model of something we know very little about, we are only now learning that the famous T-Rex that we all thought we know so well was actually a scavenger and possibly covered with feathers so to base your claims on a prehistoric concept we have yet to discover fully is flawed foundationally.
'Drones' or multi-rotors are the worst aerodynamic aircraft out there. The single reason they proliferate is that they are mechanically simple to build. The most efficient way to fly is on a wing due to the large L/D ratio the wings are capable of. 'Ant-gravity' is not possible since Einstein demonstrated gravity is not a real force, so how can you have an anti-something that is not real?
Found it! NASA/TP-2016-219072 "On Wings of the Minimum Induced Drag: Spanload Implications for Aircraft and Birds" I don't know why it doesn't show up on the technical server.
I liked so much. In 2005 I was studing flying wings for my engineering tesis. I designed mine flying wing to practice skydiving, and increase my flying time. It was surprise for me tha numbers told me that my wingtip, needed a wash-out instead wash-in. I want to learn more about your studies. Would you share the paper or contact me? Do you have a mail to share information? Best regards. Jorge Díaz
Great talk so far. So lift was originally explained to me using Bernoulli. Then they switched to Bernoulli and downwash. Then the thought was just downwash. Now we're back to just Bernoulli?
HighFlyer way I heard it explained was that when air follows a curved path, the inside of the curve has low pressure and the outside has high pressure.
These correspond to two different ways of calculating the lift on a section. Let's consider 2D flow for now (such that there are now trailing vortical structures). 1) The lift can be calculated by integrating the pressure difference between the bottom and the top of the airfoil along the chord length. The pressure on the top of the wing is lower, a result of Bernoulli's equation. 2) The lift can also be calculated by considering a control volume around the wing and using the steady flow momentum equation. This considers the downwash far away from the airfoil. Just two different ways of calculating lift. 1) considers the flow around the surface of the airfoil, 2) considers far field effects.
Bernoulli is abused when it comes to an airfoil. There is no restriction as is found in a throat of a Venturi tube, where you have conservation of mass. Air mass following a curve does experience lower pressure. In fact air travelling underneath an airfoil also experiences a reduction in pressure due to the slight curvature of the bottom part of the airfoil. The difference in pressure between the top and bottom part of the airfoil partly explains lift. There is also an exchange of momentum between the surrounding air mass and airfoil. As the flow going over the airfoil is slightly faster than the flow underneath (remember difference in pressure), the flow at the trailing edge follows a downward path, hence downwash (which also affects the horizontal stabilizer). The flow over the wing produces an effect called entrainment where the surrounding mass is pulled in the direction of the flow.
No contradiction. The Bernoulli effect is real and it explains the exact mechanism by which lift appears on the wing. But any wing which produces the Bernoulli effect (cambered wing, symmetrical wing at an angle of attack) must also produce downwash behind it. If there is no downwash, there is no lift. That action (downwash) produces the opposite reaction (lift).
F=ma Call it “downwash” leaving the wing; or call it “upwash” approaching the wing, or a combination...either way, if you want lift, the wing has to push down on the air. There’s a net acceleration of the air downward. Meaning the difference in vertical-velocity between the air entering vs leaving will be more-downward, or at least less-upward.
At 2:36 he describes a model of bypass fan blade, not an aircraft. I'm sure it has lift. I'll bet the amount of lift it has is too weak to be practical. And if that bypass fan blade is going to do any work it needs to increase its angle of attack. And if a wing is going to get any work done it needs to push down on air.
23:49 I disagree. Is he saying if the winglet was connected by a pin connection it would rotate forward? That violates conservation of momentum. There is no way an airfoil can produce a net thrust into the flow stream. If that was the case it would fly at infinite speed.
You're confusing induced drag with parasitic drag. We're only looking at induced or "vortex drag" here. Winglets can reduce induced drag by providing "induced thrust". But they actually increase parasitic drag of the wing. So above some velocity you'd be better off without winglets. So yeah, if you ignore structure, weight.. then winglets are usually worse than just extending the span.
@@xnoreq I am not confusing those things. I disagree with his interpretation of facts. He's given this talk before, Note at 37:23 he's removed the axis from his proverse yaw measurement graph, (the green line) because this raw measurement never crosses the axis he never recorded a left yawing movement with a left rolling moment, just less of it. He omits this graph in later presentations as well. I think his research is excellent but he is inflating his results here and even states in presentation you can have lift as well as upwash behind the foil. I think this NASA program is a more a study of his pupils and if they ever challenge a superior on assumptions and not a study of wing loading distributions...
@@backyardgarage912 You do confuse different kinds of drag. What you objected to in you first post actually are the facts... as I tried to explain to you. Your interpretation of them is wrong.
@@xnoreq So you're telling me what my objections are? I asserted Al Bowers thinks a NET force is applied forward by winglets, which you explained is not true. We are in agreement. Al Bowers is misinterpreting, or at least misrepresenting the facts, not us. I hold that when you "Lay a winglet flat" like he proposed you do, and then add a control surface there, you do not reap the same drag reduction benefits. His findings are misleading.
@@backyardgarage912 Bowers doesn't claim what you object to. Your objections would be partly valid if he did, but he doesn't. It looks more like you don't realize that he's talking about induced drag which either you don't know, understand or confuse with parasite or total drag. The "thrust" of the winglets is relative to the rest of the wing. So yes, if it's connected by a pin connection it would move forward. That's a simple fact which you can disagree with all you want, but reality doesn't care about opinions.
Mark 5:30 Like most, if not all, respected journals were ran and run by a class of people, one generation after another, in a closed circle and spiral up to a very high place, place above the president and above the cloud, invisible and untouchable. Most papers they published (promote) were author by associate class of their choice. Appears public is closed inside.
If the wingtips of a swept back flying wing are washed out (twisted) to the point that they push down on the farthest aft part of the aircraft this would seem to have a similar effect to reflex (upturned) trailing edge in promoting pitch stability.
Incorrect. Bernoulli is about CHANGES in speed which is Acceleration NOT speed. Acceleration is toward the lower pressure of a Pressure Gradient. . The fast air out of a blower is at atmospheric pressure, NOT below it. . The higher (static) pressure inside the blower pushes more than the atmosphere does and, therefore, because of the net force toward the lower pressure, Accelerates the air out into the relatively lower atmospheric pressure outside the blower. It is Newton in fluid. . The higher potential energy of pressure inside the blower is converted to the dynamic pressure of kinetic energy in the (now Accelerated)jet of air, at the lower pressure of the surrounding atmosphere.
I wonder what the aeronautical engineers would say about a model aircraft trainer, high wing, plenty of dihedral, flat bottom airfoil, that flies just fine with no ailerons, just rudder, elevator and throttle? Yaw AND roll control with just a rudder. In fact, with just the rudder, you can do a complete roll. I can't think of one thing that such an airplane can't do that one with ailerons can do. Of course, lots of dihedral is the answer, something that the Wrights didn't utilize. Most WW1 aircraft had none, some did like the SE5A. What if somebody built a man carrying aircraft scaled up from a successful, rudder/elevator trainer? Such as the Sig Kadet. www.sigplanes.com/SIG-KADET-MARK-II-KIT_p_48.html Would it get certified based solely on it's proof of airworthiness demonstrated by the model? That begs the question, does such a home built exists?
Yaw - roll coupling makes for easy trainers to learn flying model aeroplanes. However, they are not very good for crosswind landings where you need independent roll and yaw control. Therefore, for full size aircraft this concept has very limited use.
dos such a homebuilt exist ? yes! skypup ultralight has pitch and yaw, no ailerons, and can land a crosswind in a crab because of high dihedral. Plans only no kits. Hard to find plans but they are out there if you look.
Not gonna lie, my RC flying wings are easier to Fly than my other conventional RC planes. I relate to that slap on the back of the head... My flight instructor does that if I start slipping in the turns... but because it is a 152 he just uses his hand..
This theory of low pressure has been proven wrong. The air over the wing does NOT increase in speed. You can have a perfectly flat wing fly just fine. For golly sake, just look under any plane flying close to the ground and you will see where lift comes from
I see fighter jets doing high G maneuvers and they have a cloud of water vapor fog forming on the top of their wings. If this isn't low pressure then what am I seeing? Yes a flat plate wing can fly, but is it as "just fine" as an airfoil?
NASA scientist: is famous, solves longstanding problem in aerodynamics other people couldn't even see. Sending airplane to another planet. Random gui on Internet: baby talk. You got anything or you gonna just make noise?
wow, awsome it's 2022 and I'm seeing this video for my first time. He is good till the 13th minute area. saying Wright brothers were the first to ever fly. yep that's what we were taught in school. school taught all of us , crap, lol yep test was another one. fact an identical replica of the very first plane is in a restaurant ( of all places) in Pittsburgh Texas. I've seen it touched it etc. the real one flew in Paris world fair couple years before Wright Brothers got credit at kitty hawk. turns out fir a fact, several people around the world were trying to invent the plane at the same time. They all had a little different approach than the other guys. but at the end of the day , there were multiple people working on it. do back to yhe first one , yhe name of it is "Ezekiel Airship". it did fly, it did fly more than a hundred foot. in fact it was quite the plane. The Mayer. of Pittsburgh and my father were real good friends. Bith are gone now. but the Mayer was a lot older than my Father, he told my father several decades ago that he personally saw it fly around Pittsburgh numerous times, until they took it to Paris for the world fair, and wrapped it around a telephone pole. and thus. the reason for the identical replica. Some people like to believe what they learned in school had to be true and it scared them that they may have learned error.
There's much controversy. The replica wasn't "identical". It was constructed from the one remaining photo. It was not very controllable. There were several other planes that got off the ground but none had the three axis control needed to fly successfully. en.wikipedia.org/wiki/Ezekiel_Airship
To be impressed here at all requires total ignorance of what the Horten Bros. achieved 70 years ago with no NASA budget, no engineering degrees, no computers. Google it........
5:35 What you just said was an old theory that has been debunked. If the paper doesn't go beyond what you said here, then the editor was right to refuse your publication - according to current knowledge this is nonsense. :|
Um, what exactly is nonsense? He's not promoting the "longer path/equal transit" theory and downwash is a result of lift, not the cause of it. I'm pretty sure this sort of thing is discussed where he works.
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Amazing. It was a real pleasure to see this update, as I was not aware of it (I was looking for an old Albion's AMA video). I have been following his work since late 2011 and I am fully aware of his progressive findings, and the way this update is outlined it just simply marvelous. Way to go, Al!!!
Much appreciated sir, thank you for making it public
Great talk. Washout has always been a positive part of the wings that I have built and flown over the years. Your explanation on modifying the span wise distribution of lift to promote pro-verse yaw and moving the tip rotor slightly inboard of the tips on your wing design is a brilliant solution.
Thanks guys!! Love me a good wing plane!!! My first plane I built over 15 years ago was a Zagi XT wing. I spent over 5 months building it, sanding the leading edge of the wing, making sure I used the same amount of tape, and glue, to get it perfectly balanced. I know, it should not have taken that long to build, but I wanted it to be perfect. I still have the Zagi wing, and still fly it occasionally, but not often, because I don't want to lose it. Thank you guys for all your hard work, you make it possible for us modelers, to have fun enjoying the hobby. I always wanted to be a astronaut or just work for NASA. That dream, just wasn't in the cards for me, but that doesn't stop me from being a space ranger, right here on the ground !
Thank you. Thank you. This was the most amazing lecture.
Amazing lecture. It’s a wonderful supplement to my aerodynamics courses for my aerospace engineering degree. I hope to one day work with people like Al Bowers
he is thinking out of the box; a pleasure to listen to this guy.
I am sooo amazed! I will try to model such a plane in CAD with the additional resources i found in the comments. It would be sooo exciting to build a model and show it to all my glider pilot friends! This is the most inspirering video i have watched in the last year!
As a glider pilot and mechanical engineer I find your work amazing. Great work
This is stunningly useful for so much aero and hydrodynamics
your work your presentation is a real inspiration. I do not know if I am more impressed by the story starting from Prandtl or by the end result of the design.
That Sir is absolutely brilliant.
Excellent!
GREAT FUN! thanks for this!
That's because the AMA is full of Aging narcissist and reprobates.. The gas flying clubs are a great thing because they can stay down there and then the family has time away from all that narcissistic mannerisms it gives them times of relief ..
Thanks !
Amazing
Wow!! Fantastic....finally starting to quantify tip/ pro-adverse yaw . Yay materials science to allow test models to be built...
Very interesting lecture. Learnt a lot, thank you Al
Really amazing lecture, even for the 'uneducated' like me. In my mind birds are doing vortice unscrewing. Perhaps fine wingspan pressure sensing plus wing section morphing going to be the future
Blanik L-13 that is very old CzechoSlovakian glider made out of the sheet metal :D I have been flying on that machine too :D It is one of the most iconic gliders of 90s. Great to hear that glider made in my country has been widely unsed by the mighty NASA and US Air Force.
I'm glad to say I use to fly L-13's when I was about 14. The USAF academy I believe flies L-23's, not 13's. And most L-13's have been grounded for a while due to an airworthiness directive pertaining to the wings root spar attachments.
There is insufficient static air pressure at high altitude to provide a pressure differential to support an airplane with high wing loading (many jet fighters). Bernoulli is an inadequate model for wing lift.
The reaction model - lift is the reaction to the change in direction of the flow caused by the wing - works. Indeed it works in turbines, axial compressors with reaction blades.
Horton vs Prandtl. Hortens interest in washout was positive pitching moment necessary for longitudinal stability of a flying wing. Prandtl interest was efficiency. So Bower right, they were talking about different things.
Extrapolating avian “technology” to airplanes is interesting exercise if this kept in mind: birds are the original fly by wire relaxed static stability fliers.
Clarence Cloaca It also works for water skiers.
Static air pressure is not relevant to lift calculations, it is contained in the air density value.
@@mikenottis6252 Unless you're talking about hydrofoiling of some type water skiing bears no relation to birds or planes flying.
1:44 omg peter trucker is genius. that was so profound. that quote flipped my life up side down
I think Alexandre de Saint Exupery was one of the pilots who started flying rescue flights on mountain slopes in the Alps. He studied birds before doing so. He died on a mission over the Mediterranean Sea during WW2.
I may have a nice solution for wing tip control, I mean with reduced drag.
Antoine.
im working on a foamboard flying wing rc glider and im gonna try to use this info myself, hopefully the days of winglets are over
I just want to know how to build a PRANDTL-D big enough to carry me.
Mark 18:10
Birds do active controlled stability that men made planes do not.
By vectoring their only tail fin, birds can generate pitch and yaw forces.
Yes, many birds do use their tail to generate forces, but with something like a gliding albatross their tail is so small and close that it has virtually no effect on turning, because they don't need agility.
Kevin Shen
I agree, particularly on glide mode. Shorten right wind to yaw right and varies wind span to pitch up or down, unlike in dive mode when food is in line of sight, on that case tail steering is more effective.
Might have to change to topic of my PhD thesis...
Have you discussed this with the Open Rotors team?
Man this is a tough crowd. Guy is entertaining and funny, sounds like the audience is asleep.
5*!
Scanivalve modules are actually way smaller Al! They're expensive but are super useful!
The talk is 6 years old I guess... wee they smaller also 6 years ago? your comment is just 1 year old, and maybe they got further developed and got smaller in the meantime.
@@klausbrinck2137 ooh yeah, they've been making digital transducers for many years at this point. It's a tremendously small industry though so I don't blame anyone for not knowing about them
From Videler's Avian Flight: "Boel (1929) refers to experiments by C. Richet whose pigeons were capable of apparently normal flight with all secondary, tertiary, and 3-4 proximal primaries removed." Several other experiments cited draw similar conclusions, including one where the secondary coverts were removed as well. How is this possible if the outermost primaries function as winglets, rather than lift generators?
Because the main lift is created by the coverts and not the remiges, especially not at the tip where lift is lowest.
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I did some research to understand what it is exactly but don't find any explain for dummy, bell 🔔 shape ? With a twist ? Visually not maths formula ??
Would this apply to hydrofoil wings also?
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Hi,
1. at 20.30 Al Bowers says there are 8 new planes that have used the lift curve the espouses. Does anyone know what these 8 aircraft are?
2. I understand there are 2 solutions, span constrained and span unlimited. Has anyone thought of following the span unlimited route and then reducing it to fit the constraint on span. Would all the good effects be lost?
3. As I understand it, if you can get the upwash to such a degree that the lift vector 'points forward' then you get thrust / proverse yaw. Does this require a constantly swept back wing, i.e. swpet back from root to tip? If you look at the planform of a bird the inner section has a bit of sweep back and a bit of sweep forward, which can be approximated to a straight section. It is only the outer sections of a birds wing that is swept back. So, does this mean we should construct flying wings with a straight constant chord center section, with a zero pitching moment airfoil, and with swept back outer section which have appreciable washout?
great question. Al ? You there ?
On your taxes you can probably make a donation to this program at NASA.Prandtl wing program.
It’s likely that the B-2 has its decelerons open to increase its radar cross section.
Phos9 looks like it’s slowing down to refuel
What I don't understand is the leap from taking a vertical winglet and"laying it flat", how is it a winglet if its laid flat in terms of how winglets work? I'd also love to know more about the relationship of winglets to washout because if you lay a winglet down to horizontal as is suggested here your washout affects the AOA of that winglet not so? I get the effect of a raked wing tip as seen on modern airliners but again with wing flex these are almost vertical and thus effective in producing thrust and improving efficiency but Al's wings are rigid and the horizontal tip is just that, a wingtip or extension of the wing how is that in any way a winglet? Another thing that puzzles me on flying wing theory is the idea of setting incidence, in reference to what? How do you attain an incidence with no fuselage or stab to determine airflow angle? If its just a wing its incidence is determined purely by pitch and can't be fixed or set at a predetermined angle because there is nothing to determine relative airflow angle against?
You only get "Proverse Yaw" from the increase in lift due to the control surfaces...but there is a "Thrust" component instead of an induced drag component due to the heavy washout of a Prandtl wing.
This then means you can eliminate an empennage altogether and use Elevon mixing. Saves drag and Weight
I always thought birds twist there tails to compensate for yaw, but I suppose the must twist there wings slightly !
They do both, they also use differential sweep. Clever things those birds.
Is someone able to help with this; I understand what they have done, but one part confuses me slightly which is the upwash after the wing at the tips. In my head I had thought of lift essentially being equal to downwash, if you accelerate a mass of air downwards you feel and equal and opposite force upwards (lift), so I assumed that any upwash created in the wake would be creating negative lift? But from reading the research paper the wing produces lift along its span, anyone know a bit more about this? Thanks.
read his paper:
ntrs.nasa.gov/api/citations/20160003578/downloads/20160003578.pdf
As I understand it, that's drag not negative lift.
@@hubmonster5559 drag acts in the direction of the airflow whereas lift, acts perpendicular to the free stream airflow. ‘Negative lift’ would act downwards whereas drag acts to the rear of the aircraft.
Lots of talk about birds and learning from how they do it. And of course, birds don't have a vertical fin. There IS one, flying creature that did have a vertical fin but that fin was on it's head. Yes, the Pterodactyl. Many years ago, a scale model of such a creature was built. It was a glider and was towed up to altitude. The vertical fin up front proved to be very effective.
Now the question is, why did the prehistoric creature need a vertical fin and birds don't? I suspect the answer lies in the fact that the bird has a horizontal stabilizer that can be tilted vertically and act as fin as needed, virtually instantly. I've seen them do this.
The pterodactyl had a very poor horizontal surface that was made even more inefficient due to its legs being part of the structure. Hence the need for a vertical fin upfront.
What the engineers don't seem to be aware of as it pertains to birds, is that they feel their airplane directly, as they fly. RC Modelers need to fly by sight alone. If you fly from inside the airplane, you have some feedback by way of the seat of your pants, as they say. But a bird feels his plane, his entire body, not just by the seat of the pants, so to speak. And the feedback is instant and it's reaction is instant.
Imagine if you could do as they portray in the movie, Avatar. Transpose yourself into the body of say, a hawk, eagle, even a pigeon, you name it. What might we learn from that experience?
You would learn that you can change virtually any aspect of your machine instantly. Angle of attack. Pitch and roll. Sweepback. Dihedral. Thickness of the airfoil. The feathers themselves provide feedback along the entire span of the wing. Heck a bird can fold it's wings back and make it disappear as with when they dive for their prey. In a flash, they become a ballistic missile,,, almost.
But with the advent of drones, including man carrying versions, all of this wonderful flying on a wing may become obsolete. And if ever ant-gravity machines become a reality, well, that would change everything. I'd bet though, there would still be builders and flyers of these things that we're all so fascinated with.
"I'd bet though, there would still be builders and flyers of these things that we're all so fascinated with." that is the best closing line that you could have chosen! Thanks!
You're missing the science here, the albatross he keeps referring to has no usable vertical stabilizer and only a very small horizontal stab proportionately speaking and is as such a flying wing - as for the pterodactyl I keep bringing up when I hear folks say "a scale model was built" that its not possible to build a scale model of something we know very little about, we are only now learning that the famous T-Rex that we all thought we know so well was actually a scavenger and possibly covered with feathers so to base your claims on a prehistoric concept we have yet to discover fully is flawed foundationally.
'Drones' or multi-rotors are the worst aerodynamic aircraft out there. The single reason they proliferate is that they are mechanically simple to build. The most efficient way to fly is on a wing due to the large L/D ratio the wings are capable of. 'Ant-gravity' is not possible since Einstein demonstrated gravity is not a real force, so how can you have an anti-something that is not real?
@@aliptera " Einstein demonstrated gravity is not a real force" shoot... what is it? does it not do work?
What is the document number of the paper he is showing at the end? I am looking at NASA technical server, but not showing up with what I got.
Found it! NASA/TP-2016-219072 "On Wings of the Minimum Induced Drag:
Spanload Implications for Aircraft and Birds" I don't know why it doesn't show up on the technical server.
How do u accurately design a prandtl wing rc plane using foam?
I guess we have to read the paper ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20160003578.pdf
I liked so much. In 2005 I was studing flying wings for my engineering tesis. I designed mine flying wing to practice skydiving, and increase my flying time. It was surprise for me tha numbers told me that my wingtip, needed a wash-out instead wash-in. I want to learn more about your studies.
Would you share the paper or contact me?
Do you have a mail to share information?
Best regards.
Jorge Díaz
his paper is in the description of the video
ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20160003578.pdf here it is
anyone know where the latest paper he described is? I can only find the paper from 2016.
I found his 2021 paper, on the NASA site.
any updates on this technology?
Great talk so far. So lift was originally explained to me using Bernoulli. Then they switched to Bernoulli and downwash. Then the thought was just downwash. Now we're back to just Bernoulli?
HighFlyer way I heard it explained was that when air follows a curved path, the inside of the curve has low pressure and the outside has high pressure.
Phos9 if the inside had low pressure and the outside high wouldn't push the wing down?
These correspond to two different ways of calculating the lift on a section. Let's consider 2D flow for now (such that there are now trailing vortical structures). 1) The lift can be calculated by integrating the pressure difference between the bottom and the top of the airfoil along the chord length. The pressure on the top of the wing is lower, a result of Bernoulli's equation. 2) The lift can also be calculated by considering a control volume around the wing and using the steady flow momentum equation. This considers the downwash far away from the airfoil. Just two different ways of calculating lift. 1) considers the flow around the surface of the airfoil, 2) considers far field effects.
Bernoulli is abused when it comes to an airfoil. There is no restriction as is found in a throat of a Venturi tube, where you have conservation of mass. Air mass following a curve does experience lower pressure. In fact air travelling underneath an airfoil also experiences a reduction in pressure due to the slight curvature of the bottom part of the airfoil. The difference in pressure between the top and bottom part of the airfoil partly explains lift. There is also an exchange of momentum between the surrounding air mass and airfoil. As the flow going over the airfoil is slightly faster than the flow underneath (remember difference in pressure), the flow at the trailing edge follows a downward path, hence downwash (which also affects the horizontal stabilizer). The flow over the wing produces an effect called entrainment where the surrounding mass is pulled in the direction of the flow.
No contradiction. The Bernoulli effect is real and it explains the exact mechanism by which lift appears on the wing. But any wing which produces the Bernoulli effect (cambered wing, symmetrical wing at an angle of attack) must also produce downwash behind it. If there is no downwash, there is no lift. That action (downwash) produces the opposite reaction (lift).
but I see little similarities between this wing and albatross's wings, I don't see how it can explain why albatross doesn't need tail stablizeres
I think the horton brothers figured this out along time ago with the wing twist!!! "RIGHT"?
But they didn't get proverse yaw
F=ma
Call it “downwash” leaving the wing; or call it “upwash” approaching the wing, or a combination...either way, if you want lift, the wing has to push down on the air. There’s a net acceleration of the air downward. Meaning the difference in vertical-velocity between the air entering vs leaving will be more-downward, or at least less-upward.
At 2:36 he describes a model of bypass fan blade, not an aircraft.
I'm sure it has lift. I'll bet the amount of lift it has is too weak to be practical.
And if that bypass fan blade is going to do any work it needs to increase its angle of attack.
And if a wing is going to get any work done it needs to push down on air.
the downwash model is not correct explanation for lift, and there are many aerodynamicists who can and have proven this.
@@SoloRenegade Exactly! No commercial aircraft would ever leave the ground otherwise.
Where can I download the report?
amaflightschool.org/PRANDTL
I assume your flying wings all use a reflexed airfoil?
airfoiltools.com/airfoil/details?airfoil=prandtl-d-root-ns
airfoiltools.com/airfoil/details?airfoil=prandtl-d-tip-ns
ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20160003578.pdf
So how does the albatross control pitch? I'm assuming they have no reflex in their wings.
Is it with those webbed feet?
Ken Javor albatross has tail, All birds have it, swift has quite big tail too
jnb ostensibly the albatross doesn’t use their tail, I imagine they could pitch by moving their center of lift fore and aft.
holy crap thank you for this
23:49 I disagree. Is he saying if the winglet was connected by a pin connection it would rotate forward? That violates conservation of momentum. There is no way an airfoil can produce a net thrust into the flow stream. If that was the case it would fly at infinite speed.
You're confusing induced drag with parasitic drag. We're only looking at induced or "vortex drag" here.
Winglets can reduce induced drag by providing "induced thrust". But they actually increase parasitic drag of the wing. So above some velocity you'd be better off without winglets.
So yeah, if you ignore structure, weight.. then winglets are usually worse than just extending the span.
@@xnoreq I am not confusing those things. I disagree with his interpretation of facts. He's given this talk before, Note at 37:23 he's removed the axis from his proverse yaw measurement graph, (the green line) because this raw measurement never crosses the axis he never recorded a left yawing movement with a left rolling moment, just less of it. He omits this graph in later presentations as well. I think his research is excellent but he is inflating his results here and even states in presentation you can have lift as well as upwash behind the foil. I think this NASA program is a more a study of his pupils and if they ever challenge a superior on assumptions and not a study of wing loading distributions...
@@backyardgarage912 You do confuse different kinds of drag. What you objected to in you first post actually are the facts... as I tried to explain to you. Your interpretation of them is wrong.
@@xnoreq So you're telling me what my objections are? I asserted Al Bowers thinks a NET force is applied forward by winglets, which you explained is not true. We are in agreement. Al Bowers is misinterpreting, or at least misrepresenting the facts, not us. I hold that when you "Lay a winglet flat" like he proposed you do, and then add a control surface there, you do not reap the same drag reduction benefits. His findings are misleading.
@@backyardgarage912 Bowers doesn't claim what you object to. Your objections would be partly valid if he did, but he doesn't.
It looks more like you don't realize that he's talking about induced drag which either you don't know, understand or confuse with parasite or total drag.
The "thrust" of the winglets is relative to the rest of the wing. So yes, if it's connected by a pin connection it would move forward.
That's a simple fact which you can disagree with all you want, but reality doesn't care about opinions.
Mark 5:30 Like most, if not all, respected journals were ran and run by a class of people, one generation after another, in a closed circle and spiral up to a very high place, place above the president and above the cloud, invisible and untouchable. Most papers they published (promote) were author by associate class of their choice. Appears public is closed inside.
I THOUGHT THAT UP WARD TURNED TRAILING EDGES ON FLYING WINGS ACTED AS DECALAGE THAT CONVENTIONAL TAILS PRODUCED AND THUS COULD FLY WITHOUT TAILS
If the wingtips of a swept back flying wing are washed out (twisted) to the point that they push down on the farthest aft part of the aircraft this would seem to have a similar effect to reflex (upturned) trailing edge in promoting pitch stability.
ยังไงปีกก็มีคุณสมบัติที่ยอดเยี่ยมในการบินแค่เรายึดติดอยู่ในกรอบเท่านั้นเป็นอุปสรรคในการพัฒนา
High flow low pressure low flow high pressure?
Incorrect.
Bernoulli is about CHANGES in speed which is Acceleration NOT speed.
Acceleration is toward the lower pressure of a Pressure Gradient.
.
The fast air out of a blower is at atmospheric pressure, NOT below it.
.
The higher (static) pressure inside the blower pushes more than the atmosphere does and, therefore, because of the net force toward the lower pressure, Accelerates the air out into the relatively lower atmospheric pressure outside the blower. It is Newton in fluid.
.
The higher potential energy of pressure inside the blower is converted to the dynamic pressure of kinetic energy in the (now Accelerated)jet of air, at the lower pressure of the surrounding atmosphere.
It's more so accelerated flow = low pressure and decelerating air = high pressure. It's about the change air encounters when interacting with a wing.
I wonder what the aeronautical engineers would say about a model aircraft trainer, high wing, plenty of dihedral, flat bottom airfoil, that flies just fine with no ailerons, just rudder, elevator and throttle? Yaw AND roll control with just a rudder. In fact, with just the rudder, you can do a complete roll. I can't think of one thing that such an airplane can't do that one with ailerons can do.
Of course, lots of dihedral is the answer, something that the Wrights didn't utilize. Most WW1 aircraft had none, some did like the SE5A.
What if somebody built a man carrying aircraft scaled up from a successful, rudder/elevator trainer? Such as the Sig Kadet. www.sigplanes.com/SIG-KADET-MARK-II-KIT_p_48.html Would it get certified based solely on it's proof of airworthiness demonstrated by the model?
That begs the question, does such a home built exists?
Yaw - roll coupling makes for easy trainers to learn flying model aeroplanes. However, they are not very good for crosswind landings where you need independent roll and yaw control. Therefore, for full size aircraft this concept has very limited use.
+hopeso, yes, it does exist, it is called the Wood SkyPup ruclips.net/video/hsLbcINWMQo/видео.html
Flying Flea has only rudder and elevator controls
@@cziesolleck skypup ultralight has pitch and yaw, no ailerons, and can land a crosswind in a crab because of high dihedral.
dos such a homebuilt exist ?
yes! skypup ultralight has pitch and yaw, no ailerons, and can land a crosswind in a crab because of high dihedral. Plans only no kits. Hard to find plans but they are out there if you look.
Not gonna lie, my RC flying wings are easier to Fly than my other conventional RC planes.
I relate to that slap on the back of the head... My flight instructor does that if I start slipping in the turns... but because it is a 152 he just uses his hand..
I wonder what the consequences of these findings are for helicopters...
I was thinking the same thing. ie Will we get new rotor shapes that are much more quiet?
No. You didn't make a mistake.
This theory of low pressure has been proven wrong. The air over the wing does NOT increase in speed. You can have a perfectly flat wing fly just fine. For golly sake, just look under any plane flying close to the ground and you will see where lift comes from
I see fighter jets doing high G maneuvers and they have a cloud of water vapor fog forming on the top of their wings. If this isn't low pressure then what am I seeing? Yes a flat plate wing can fly, but is it as "just fine" as an airfoil?
He lied when he said he is not a smart guy
Jibber jabber.
NASA scientist: is famous, solves longstanding problem in aerodynamics other people couldn't even see. Sending airplane to another planet.
Random gui on Internet: baby talk.
You got anything or you gonna just make noise?
wow, awsome it's 2022 and I'm seeing this video for my first time. He is good till the 13th minute area. saying Wright brothers were the first to ever fly. yep that's what we were taught in school. school taught all of us , crap, lol yep test was another one. fact an identical replica of the very first plane is in a restaurant ( of all places) in Pittsburgh Texas. I've seen it touched it etc. the real one flew in Paris world fair couple years before Wright Brothers got credit at kitty hawk. turns out fir a fact, several people around the world were trying to invent the plane at the same time. They all had a little different approach than the other guys. but at the end of the day , there were multiple people working on it. do back to yhe first one , yhe name of it is "Ezekiel Airship". it did fly, it did fly more than a hundred foot. in fact it was quite the plane. The Mayer. of Pittsburgh and my father were real good friends. Bith are gone now. but the Mayer was a lot older than my Father, he told my father several decades ago that he personally saw it fly around Pittsburgh numerous times, until they took it to Paris for the world fair, and wrapped it around a telephone pole. and thus. the reason for the identical replica. Some people like to believe what they learned in school had to be true and it scared them that they may have learned error.
There's much controversy. The replica wasn't "identical". It was constructed from the one remaining photo. It was not very controllable. There were several other planes that got off the ground but none had the three axis control needed to fly successfully.
en.wikipedia.org/wiki/Ezekiel_Airship
Ama- why would a bunch of senior citizen gas guys care anything about technology ..ama lmao
To be impressed here at all requires total ignorance of what the Horten Bros. achieved 70 years ago with no NASA budget, no engineering degrees, no computers. Google it........
5:35 What you just said was an old theory that has been debunked. If the paper doesn't go beyond what you said here, then the editor was right to refuse your publication - according to current knowledge this is nonsense. :|
"according to current knowledge" for thousands of years the Earth was flat.
Exactly. And now we know it's not. However there are still people today who believe that Earth is flat.
Um, what exactly is nonsense? He's not promoting the "longer path/equal transit" theory and downwash is a result of lift, not the cause of it. I'm pretty sure this sort of thing is discussed where he works.
Wow, what a massively closed mind. Bernoulli being the sole reason for lift? No-one flew before the Wright Bros? Come on!
The Egyptians did!
This guy doesn't know what he is talking about.
You don't know what you're talking about