Wow - you really went to all the trouble to try out my experiment with the dummy load, and to verify all the questions from others. I, and I think we all, really appreciate it!
I have been watching your video's for a while now. When i was in highschool here in the Netherlands my science teacher was boring and strict and that made me hate science. 10 years later i actually enjoy physics and science because of awesome teachers like you that share their knowledge on youtube. Please keep up the awesome work 😊.
LOL, good idea, maybe I'll add those when I retire and have more time. Thanks GarageWoodworks. By the way, nice channel. I'd like to learn more about woodworking and you're channel has some great ideas and projects that I like to try.
@@YeanyScience how ist the airflow behaving in Front of the Sail. I guess that Air gets sucked around the sail and joins the the redirected airflow. Lieferung the pressure in Front of the Sail. Working like the aerodynamics of an airplane Wing?
@@1islam1 islam says that no human being in existence could ever do anything better than muhammad, that he is the best of any human in all existence for infinity, but there are things he did that "the best person in existence" wouldnt do, there are things he did that werent so good, things I wouldnt do, so would that make me better than him? He told us first its allah in heaven, then right below God himself, second to God, is muhammad, and everyone else is below both of them lmao come on
This is a great experiment. You just proved that technically, it is possible to have a paramotor, and a parachute, and aim the prop upwards to take off vertically . Of course this would require a lot of power, but none the less it is totally possible. When I was younger ,I suggested this to a physics student who told me it would be like powering a bathtub, like a boat, with the motor inside the tub, so I totally abandon the idea, however the thrust vectoring concept proves that it would work.
I've spent a lot of money on college courses. I find this more interesting, and more informative, than most of them! Thanks for your great videos. I'd love to be in your class right now!
I was surprised that the tube produced any thrust at all, I would have expected it to be completely stalled and just swirling the air at the opening around. That was a great follow up but now I want to know what your instant-smoke was! It looked like you were mixing the vapor from 2 liquids to form a smoke/suspended particles.
Did I see a tub labelled 'Lycopodium powder' at one point? They're clubmoss (a primitive plant) spores ... and will also make a great fuel-air explosion! :-)
I expected the same result. After thinking about it a bit, I have a new hypothesis. Since the fan is aligned along (or near) the axis of the cylinder, the swirling air it creates is going IN to the cylinder in the center, and going OUT of the cylinder near the edges. I wonder if the Venturi effect wasn't playing a role, here. The swirling air that is going backward is near stationary (higher pressure) air. So the air outside the cylinder gets pulled into the backward directed flow, creating a net mass flow toward the rear of the boat.
There needs to be more awesome teachers like Bruce, he's built some of the best, public friendly, demos I have ever seen. Thanks for the tip, I thought I had seen it somewhere but I didn't have a clue what it might have been. I wonder if I can grow some visible crystals under a microscope.
I literally came here because my friend showed me a short clip of an airplane thruster doing some stuff and at one point bringing a giant cover down over it, upon which I asked "what is that?" and he said the reverse thrust system. That had me fucked up thinking exactly about blowing into your own sail kind of thing. Thank you!
Great demonstrations as usual Bruce! There are so much things to understand and the way you explain them is simply awesome. Thanks a lot for that!... Best greets from France! = )
Very nice demos. I'd love to see a slanted sail with a rudder (or even a keel or dagger board). The wheels of the carts serve a similar purpose, provided sufficient friction. Even more awesome would be an explanation of how one could sail directly downwind faster than the wind. Keep up the great work!
You cannot sail directly downwind faster than the wind. That is why boats with efficient hulls sail off the wind a bit, so they get some lift off the airfoil sail shape. It is actually faster than sailing directly downwind - even with a symmetrical spinnaker. But it was only a couple of decades ago that a sailboat managed to sail faster than the wind - on any tack. I seem to recall that it was a specially built boat called "Slingshot" that managed by sailing a course essentially at right angles to the wind direction.
You can also use the rudder to demonstrate the effects of adjusting the trim on an aircraft to counter apposing forces on an aircraft to maintain intended attitude of the aircraft. Off subject, but a good demonstration all the same. love watching your videos.
If you look closely, you'll see it actually did move slightly at 2:12, and again at 2:16. This leads me to believe that there is indeed some small net force with the sail in that orientation, but it's not enough to overcome the other forces acting on it, such as friction. This makes sense because even though it's taut, it's not perfectly flat-- there is a very slight curve.
TheOriginalJphyper well nothing is perfect in design. Slight irregularities in the design cause small errors. It wasn't a significant effect to be noted.
Could you try putting a tunnel of sorts around the propeller? I've been wondering if it is able to propel itself because it takes in "diffuse" air and pushes it forward in a more ordered manner
The fact that the rudder makes the boat go forwards is pretty reminiscent of how sail boats sail upwind. The wind tries to deflect the boat to one side or the other (and backwards a bit), but the rudder forces the boat to move forwards instead (if the boat didn't have a flat stern, it might move backwards, too). This is how we sailed around the world, back in the day.
Not really. The physics of sailing upwind is completely different to a sail working before the wind as shown here. A sail which can go upwind must be able to form a tear shaped cross section just like the wing of an airplane. It is this shape which generates the forward moving force, as well as a lot of sideways moving force - the drift. The drift is counteracted somewhat by the rudder but most of it is canceled by the fin or the keel. But nevertheless, the boat is pulled by the wind approaching the sail from the front and the airflow across the the sail generates the forward force. But it is not pushed by some deflected wind from the back. The beautiful old sail boats you might be thinking of (such as the one Columbus used) really could not do much more then sail before the wind (downwind). If they needed to go against the wind, they were pretty much out of luck and had to wait until the wind shifted.
Does the flat surface being close to the fan have anything to do with it going sideways. If it were farther away and could still deflect it might go more backwards as it might not have to overcome as much foward air pressure from the fan. There is probably and optimal distance. At which point you can test materials in a small degree by finding different ideal distances. Although it's probably not complicated enough to fully go over what is happening.
so since some of the air is redirected back through the fan with the cardboard sail, would the back wards cardboard sail not have as much air that redirected? Does the back wards cardboard sail go faster than the traditional looking cardboard sail? Great videos!!!
With the cup "sail", if you where to flip the fan around so it pushes air backward, wouldn't this create a lower pressure in the cup and cause less air to being pushed backwards.
Could a lateen sail be used instead of a square rig sail? Could a combination of tacking and jibing achieve a faster overall journey (than driving sails) when used in conjunction with the fan motor?
I tackled this square sail setup again because the fan cart is a popular item in science classrooms and I wasn't happy with how I left it in the last video. I used to do some sailing when I was younger and really would like to try some future demonstrations with the lateen sail and take a look at some of the basic science behind it.
Another Freediver Agreed that this would be great! The "wing" effect of a Marconi-rig will work differently than a square-rig.. especially at different points of sail! But great videos all around Mr. Yeah!
Here us my take on why this works. First of all, air molecules don't "bounce" off surfaces like some have suggested. They create flow fields and pressure gradients. If you assume that all the force acting on the propeller is in the opposite direction of the air flow it generates, it still wouldn't matter if all the air was redirected backwards from the sail, the forces would cancel. The part that is being neglected is the propeller. The propeller isn't just colliding with the air causing it to flow, the rotation and shape of the blades cause a pressure differential (Bernoulli effect) that causes the air to flow and give it linear kinetic energy. Part of the force acting on the propeller is opposite the direction of the air, but the Bernouli part is (at least partially) counter the rotational moment of the blade. For this reason, the linear force acting on the propeller could be smaller than the force pushing on the sail. You can think of the sail in terms of drag force. In this case, the larger the sail, the larger the drag force at least until you reach the maximum force produced by the air flow. Newton's laws are not violated.
Can you use PVC pipe and suck the air from top and to the sail ? i Think its going to work. or use U shape PVC pipe and suck the air from top of the sail facing forward and blowing it to the sail. ?
@8:30 - I believe the boat is not going forward based on the fan hitting the sail....and the loss of rotational force is not due to the rudder entirely, but rather the vibration of the motor is directly influencing the rudder in the water, which causes the rudder to act as a moving "fin." Take the fan blades and sail completely off and run just the motor with the rudder, I'll bet you get movement.
I always think about flight, I’ve built many full size airplanes. But the idea of an air filled parachute has been with me since I was a kid. I had a powered paraglider for a bit, The difference between a paraglider and a parachute is that a parachutes has pores in it. The air goes through a parachute. A paraglider if you blow on it, you can’t force and air through, it’s an inflatable wing. But my dream was to make an old school parachute out of paraglider fabric…. Non pourus fabric. (A sail). You have a giant parabolic surface. Then you blow air up into it. The thrust comes from it blowing back (like a reverse thruster). You’d have the worlds safest aircraft, If it quit, you’d just float down. Thing is, it would also be the worlds least efficient aircraft.
if the net force is 0. does it come to a stop faster if when you push it because the fan adds stability through friction or something. I'd really like to see that :)
Two things I noticed. 1.) the first sail was pretty close to the same area as the sweped disc of the propeller. This could be one reason the reactions canceled each other out. The second thing was that the first sail was also very close to the propeller. Two possible experiments. 1.) put the original sail at least one fan blade diameter ahead of the fan. 2.) make a contoured sail that has the same area as the original sail, and place it at least one fan-blade diameter ahead of the fan. Another experiment is to put the larger contoured sail at least one fan-blade diameter in front of the fan. See if it Propels the cart faster than the new, smaller contoured sail. I predict that it will.
This reminds me of a question I had awhile ago. If a space ship had uneven thrust behind it and started spinning, could Gyros keep it going straight if they were strong enough? The rudder causing that to travel straight reminds me of that question. You were actually able to get it to go straight by a completely different mechanic which is amazing to me. I guess that would be sort of like the tail rotor of a helicopter.
HI Joel, good question, my guess if it is oriented correctly the gyro should be able to straighten out the movement. I'm not sure when I will get to it but I've wanted to do a segment on gyroscopes and I will add that to try in the segment.
I think this would work for a while. The gyro works by having a spinning mass which is carefully controlled to take advantage of Newton's 3rd Law - for every action, there is an equal and opposite reaction. By applying a torque (rotational force) on the gyro (either through a motor or friction), an equal and opposite torque is experienced by the rest of the space ship. The imbalance in thrust creates a torque, which will cause the ship to turn. The ship can apply a countering torque on the gyro, such that instead of the ship turning, the gyro turns instead... up to a limit. The turning isn't adding rotational speed, but rotational acceleration. In order to counter the imbalanced thrust, you have to keep accelerating the gyro. Eventually, this will induce centripetal forces inside the material of the gyro which tear it apart.
It still doesn't make sense to me how a curved sail is able to produce thrust in this scenario. Because if you picture it, the fan produces thrust by spinning curved blades that push off the air perpendicularly to the blade movement and that in turn pushes the blade in the opposite direction. But then the curved sail produces thrust by redirecting the air which is essentially pushing off the air like the blade did. And the part that baffles me is that the air got momentum from the fan and then it transfers that momentum to the sail. So how can the sail win over the fan? I picture the sail like a mirror reflecting the light; maybe a corner reflector would be more analogous.
So if this worked couldn't we do the same thing with a "Solar Sail" ? You could reach some pretty high speeds and you'd never get stuck/stranded somewhere with insufficient light to drive the sail.
Spinning because of torque, your prop might be a little pointed up and that would cause p factor. That uneven air, is known as (p factor). When you take a prop. If it’s perfectly level both the up and down blades are at the same angle. If you put it at an angle the descending blade catches more air. If you take your hands and make a prop with them. Them tilt the “prop” up, you’ll see the angle actually changes.
That’s why sailboats have keels they take any energy that’s put into the sales that’s not at the right angle and forces some of that energy in the direction you wanna go. Also helps keep the boat upright but that’s somewhat obvious.
Loved your smoke generator! A bit of Chemistry in the Physics experiments! But ammonia and HCl would not be a good alternative in front of a class, I think. Lycopodium is messy. A smoke machine would be a safer alternative or a ultrasonic humidifier fog generator.
isolate the fan with its own air intake separate from the air being pushed back from the curved sail to prevent recirculation . the fan should have a tube over it extended past the back of the boat so suck in clean air and point the other end directly to the sail. itll move so much faster.
i have doubts as your kart is too bulky ... i know for a fact that the forces cancel out because you cant auto generate forces from nothing and get a positive outcome
on the water, it spins because motor turning to one side. Airplanes with one motor, they have same problem it called "thrust angle". you can make video about that cause its rly interesting
Hi :) your experiment is really interesting. I am bit into sailing so I'd like to see the effects of blowing into your own sail using a modern sail concept :)
You should be able to improve performance beyond what fan alone can do. Fan moves smaller amount of air at high velocity. F = MV is the force. But P = MV^2/2 (power to operate fan). If airfoil can convert small M large V to large M small V efficiently, then force can be increased for given power. This is why helicopters use large, slow-turning rotor (for static left), and airplanes use smaller propellers turning fast (for cruise speed). The airplane wing converts some of the "speed force" to a larger "lift force". Properly-designed "wing sail" should be able to do the same. Try first blowing across the curved sail from the side. You should be able to get faster boat versus blowing out the back with fan only.
+Bruce Yeany Nice set of vids but what you don't explain here is that sails work as wings and therefore it is the depression caused by the sail and not the wind pushing into the sail that makes the boat go forward. Thanks for all the others vids :)
Thank you for taking time to explore the comments and suggestions we contributed from the earlier video on this subject. You mentioned in this video that you believe you don't understand how sails work. If you will allow me a moment, we can explore this together -- and please feel free to correct me when my "science" strays or fails me. In my "armchair physics mind," I see no difference between the sail and the boat itself. Air is a thinner medium than water, but the same principles apply. In essence, the sail "floats" on the air at a perpendicular to the boat floating on the water. First, let's consider the boat. It floats because the area of the boat is great enough to disperse the downward force of gravity exerted on the boat's mass and displace an amount of water sufficient to offset that downward force. The boat moves with the water current because the force of the current applied to the boat is greater than the force of the inertia-at-rest applied to the boat. Now let's consider the sail. In order for the sail to work, there must be sufficient area of sail-cloth (we'll come back to this in a moment), to overcome the force of the boat's inertia-at-rest (rather than gravity, per se) and displace an amount of air (behind the sail) sufficient to overcome that force. The boat moves with the air current because the force of the current (captured by the "billowiness" of the sail, and thereby multiplied) applied on the boat is greater than the force of the inertia-at-rest applied to the boat. The larger the surface area of sail provided and the more billowy the sail (without reaching the point of diminishing return), the more the air current can be captured and directed to help propel the boat in the desired direction. Note that the last sentence reads "...in the desired direction." A good sailor can tack into the oncoming wind and use the position of the sail in concert with the rudder to move the boat forward at a vector to that wind. Now let's go back to the issue of the area of the sail-cloth. Before self-propelled ocean-going vessels, there were the tall-masted ships. As these ships demonstrate, the area of sail-cloth does not have to be provided in one large sail. Instead, the effect is multiplied by providing numerous sails of various strategic sizes, strategically placed in order to optimize wind capture and direct the harnessed energy. Does this explanation make sense to you? Have I missed (or misstated) anything?
Sorry, Sir. There is no such a thing like "force of boat's inertia-at-rest" .Inertia is not a force. The thinnest, smallest force will accelerate ( move) a giant body ( a rock, ship , or even a planet ), if there is no friction. Inertia means that a the movement of body along a straight line (constant velocity) is a state as "natural" as the state of a resting body ( "quiete"); no cause, no force is necessary for both states. Galileo understand that the uniform motion in a straight line has the same status as the uniform motion in a right line. NO EXPLANATION is needed. As Newton stated: Every body perseveres in its state of rest, or of uniform motion in a right line, unless it is compelled to change that state by forces impressed thereon. The point is : Inertia is not a CAUSE. FORCE is a CAUSE.
I remember that MythBusters once proved that you can blow your own sail; I think their explanation had something to do with certain sails being unable to absorb all the wind, although I think that this was just an initial guess.
Good job. Pretty scientific! You falsified (in the good way) my concern about angular momentum and proved me wrong. Hope this inspire kids to follow your steps (or at least know how to test if something is true or not based on evidence!!) Cheers!
Dear Mr Yeany, thank you for your excellent lessons! By the way, you have just broke the third Newton's law, have you noticed? And rightly so, that should have happened a long time ago.
what you could do when on the pond is have a second fan blowing to the side so the net force is at a 45' angle or so to the boat and so the boat goes on a circle
there are only two force on the boat. 1. reaction force to fan pushing the wind (push boat backward) 2. force that wind hit on the sail (push boat forward) the fact that boat going forward means that wind going forward is smaller than wind going backward in the momentum perspective. it's like ball thrown to wall bounce off more strongly. this is wired. the air is fluid not solid. maybe this is the reason. I want to know why backward wind is stronger
All things being equal this should not work, which means they are not equal. Some of the energy of the fan must be applied up and or down and not straight back. This leaves room for the energy of the sail pushing back to overtake the energy of the fan pushing forward. Causing a net force from the sail (pushing back causing it to go forward) The fan only doesn't work with flat sails because a lot of the energy gets diverted to the side instead of backward losing a lot of the forward force. The fan is always causing a net energy forward or this would not work.
I mean, it's similar to just running a fan backwards at this point, but less efficient. Or also, running a tube from the front of the fan around back again to propel it. So the florida janitor would have been better off just aiming the leaf blower behind him.
Thank you very much Mr Bruce your videos are very interesting but I don't understand English please you can translate your videos in french and thank you again for all your efforts
please show and angled sail with a rudder applying force in the opposite direction. both with wind from behind the sail and wind from the front. and cover "sailing into the wind." thanks from a subscriber.
Hi Brian, I have some ideas for it and I do want to tackle the behavior of traditional sails. I have too many plans and not enough time to get to them all.
Вы сделали из лодки вертолет )). Вам надо было для эксперимента включить реверс оборотов и посмотреть , начнет ли лодка вращаться в обратном направлении ?
Bruce you never have explained how rockets can work in a vacuum, based on Newton's third law. Let me recant ,it's been explained multiple times ,but how could we demonstrate this?
johnathan bowman - Newton's 3rd Law states that when one body applies force to another body, an equivalent force is applied back to the first body. A rocket combusts fuel, which reacts and rapidly expands. This fuel's expansion is directed in one direction, so all of the force applied to the fuel is in that one direction. The fuel (or rather exhaust at this point) then equivalently exerts a force back upon the rocket it is being expelled out of, driving the rocket forward. This reaction works exactly the same in or out of a vacuum. The major difference in a vacuum is that you don't have air resistance, which actually slows the rocket down more than speeds it up. While it could provide more for the exhaust to push against, it exerts a great amount of friction against the rocket. This is why rockets are more efficient in a vacuum. There isn't a very easy way to test this on a small scale, but for something similar, Cody's Lab has a few videos of explosions in a vacuum chamber showing that the velocity of the debris is higher in the vacuum than in atmosphere.
I love your videos Bruce, but as an adult now ,I have questions about some of the science I was taught in school .That's why I keep asking you about this particular topic . I would appreciate it if you would try to think of an experiment that would demonstrate just exactly how a rocket could work, in a huge infant vacuum chamber . Look into it. This is supposed to be science right, don't call me an idiot for asking questions as a lot of you guys do for this particular thing ,in the comments . Not you Bruce, you're a good guy. Thanks in advance for anything that you could come up with for a demonstration.
GuyNamedSean It's not necessarily a rocket working in a vacuum, that I'm concerned with, it is the very nature of the vacuum of space. I mean doesn't a vacuum require a vacuum chamber? I would be very curious to know if a very small rocket ,like a bottle rocket, (firework) would function properly in the huge vacuum chamber that NASA has. This is the only chamber that I can think of that's large enough to even come close to testing this thing that were told about space, being an infinite, ever-expanding vacuum. I know that people like the Mythbusters have tested this on National Television but their vacuum chamber was so small that I would have to be inclined to think that the rocket was actually pushing on the sides of the chamber. I guess your next question is why would I wonder this. And my answer would be money .NASA takes 10 million dollars a day from the taxpayers of the United States, for a small group of people to go to places that no one else can. It's a pretty good scam if you think about it.
Johnathan bowman, it's a good problem and I've taken a look at how to prove it, the problem comes back to building a large enough vacuum chamber. Something I've wanted to do but has been cost prohibitive so far. I will keep looking because there are some other experiments I want to try also.
johnathan bowman - Did you read my reply to your other comment? It goes into some detail about your inquiry as far as my understanding of it goes. I'll stress that I'm not specifically a physics student, though I do take time to study astronomy, cosmology, and rocketry in my free time.
Well done Bruce! My suggestions: use an EDF (electric ducted fan) instead of a propeller, smoke instead of powder, and light as I did in my Coanda effect video ruclips.net/video/aF92B6Gon3M/видео.html @1:35 in a dark room with a spotlight coming from behind, shining towards the lens. A visible airflow can explain a lot.
Hello Giesbert, thank you, great job on the Coanda effect, something I played a round with a bit but your method is much more direct than mine. I appreciate the comments and will keep them in mind for a couple future ideas I want to try .
Wow - you really went to all the trouble to try out my experiment with the dummy load, and to verify all the questions from others. I, and I think we all, really appreciate it!
I thought it was a good idea and was curious to know what would happen. thanks
I like how he takes time to read suggestions and answer questions.
a teacher that likes to teach so much he even teaches in his off time! Our country's children need more people like you sir. A lot more.
I have been watching your video's for a while now. When i was in highschool here in the Netherlands my science teacher was boring and strict and that made me hate science. 10 years later i actually enjoy physics and science because of awesome teachers like you that share their knowledge on youtube. Please keep up the awesome work 😊.
Nice follow up. For some odd reason I'm always expecting to get homework at the end of your videos.
LOL, good idea, maybe I'll add those when I retire and have more time. Thanks GarageWoodworks. By the way, nice channel. I'd like to learn more about woodworking and you're channel has some great ideas and projects that I like to try.
I can't believe I'm saying this, but I wouldn't complain about getting some homework from you.
Thank you.
@@YeanyScience how ist the airflow behaving in Front of the Sail. I guess that Air gets sucked around the sail and joins the the redirected airflow. Lieferung the pressure in Front of the Sail. Working like the aerodynamics of an airplane Wing?
@@1islam1 islam says that no human being in existence could ever do anything better than muhammad, that he is the best of any human in all existence for infinity, but there are things he did that "the best person in existence" wouldnt do, there are things he did that werent so good, things I wouldnt do, so would that make me better than him? He told us first its allah in heaven, then right below God himself, second to God, is muhammad, and everyone else is below both of them lmao come on
This is a great experiment. You just proved that technically, it is possible to have a paramotor, and a parachute, and aim the prop upwards to take off vertically . Of course this would require a lot of power, but none the less it is totally possible. When I was younger ,I suggested this to a physics student who told me it would be like powering a bathtub, like a boat, with the motor inside the tub, so I totally abandon the idea, however the thrust vectoring concept proves that it would work.
Try things without listening to other people!!
Even ignore so-called physics and just do it!!
You are THE BEST TEACHER
I am a molecular Cell and Biology major, but yet I still enjoy your videos. Keep it up Mr. Yeany!
I've spent a lot of money on college courses. I find this more interesting, and more informative, than most of them! Thanks for your great videos. I'd love to be in your class right now!
Bruce Rocks! A great teacher - genuine enthusiasm is key to great teaching.
I was surprised that the tube produced any thrust at all, I would have expected it to be completely stalled and just swirling the air at the opening around.
That was a great follow up but now I want to know what your instant-smoke was! It looked like you were mixing the vapor from 2 liquids to form a smoke/suspended particles.
Nick Moore Good to see you here. Bruce's videos are great! I'll bet the smoke is made from hydrochloric acid and ammonium hydroxide.
Did I see a tub labelled 'Lycopodium powder' at one point? They're clubmoss (a primitive plant) spores ... and will also make a great fuel-air explosion! :-)
I expected the same result. After thinking about it a bit, I have a new hypothesis.
Since the fan is aligned along (or near) the axis of the cylinder, the swirling air it creates is going IN to the cylinder in the center, and going OUT of the cylinder near the edges.
I wonder if the Venturi effect wasn't playing a role, here. The swirling air that is going backward is near stationary (higher pressure) air. So the air outside the cylinder gets pulled into the backward directed flow, creating a net mass flow toward the rear of the boat.
There needs to be more awesome teachers like Bruce, he's built some of the best, public friendly, demos I have ever seen.
Thanks for the tip, I thought I had seen it somewhere but I didn't have a clue what it might have been. I wonder if I can grow some visible crystals under a microscope.
Applied Science That was my guess too. Muriatic acid and ammonia. Ammonium chloride is quite hygroscopic which sucks a fog right out of the air.
I literally came here because my friend showed me a short clip of an airplane thruster doing some stuff and at one point bringing a giant cover down over it, upon which I asked "what is that?" and he said the reverse thrust system. That had me fucked up thinking exactly about blowing into your own sail kind of thing. Thank you!
Great demonstrations as usual Bruce!
There are so much things to understand and the way you explain them is simply awesome. Thanks a lot for that!...
Best greets from France! = )
Thanks, nice to hear from you again PlanGIV
This is going to get a lot more views with the "Florida janitor" viral video going around
What if the fan were sucking from the front and ducted to the rear of the sail?
Very nice demos. I'd love to see a slanted sail with a rudder (or even a keel or dagger board). The wheels of the carts serve a similar purpose, provided sufficient friction. Even more awesome would be an explanation of how one could sail directly downwind faster than the wind. Keep up the great work!
You cannot sail directly downwind faster than the wind. That is why boats with efficient hulls sail off the wind a bit, so they get some lift off the airfoil sail shape. It is actually faster than sailing directly downwind - even with a symmetrical spinnaker.
But it was only a couple of decades ago that a sailboat managed to sail faster than the wind - on any tack. I seem to recall that it was a specially built boat called "Slingshot" that managed by sailing a course essentially at right angles to the wind direction.
You can also use the rudder to demonstrate the effects of adjusting the trim on an aircraft to counter apposing forces on an aircraft to maintain intended attitude of the aircraft. Off subject, but a good demonstration all the same.
love watching your videos.
If you look closely, you'll see it actually did move slightly at 2:12, and again at 2:16. This leads me to believe that there is indeed some small net force with the sail in that orientation, but it's not enough to overcome the other forces acting on it, such as friction. This makes sense because even though it's taut, it's not perfectly flat-- there is a very slight curve.
TheOriginalJphyper well nothing is perfect in design. Slight irregularities in the design cause small errors. It wasn't a significant effect to be noted.
deep down I want this guy to have a million subscribers! he too cool
very nice, very informative with a lot of extras
awesome!!! I am brazilian and your videos are helping me SO much!! I used to hate physics and now it is my favorite subject :D
thank you, very nice that they make a difference
Excellent follow up!
2 buckets to fill the pond... efficient. :)
I'm wondering how he emptied it!
Siphon?
Could you try putting a tunnel of sorts around the propeller? I've been wondering if it is able to propel itself because it takes in "diffuse" air and pushes it forward in a more ordered manner
The fact that the rudder makes the boat go forwards is pretty reminiscent of how sail boats sail upwind.
The wind tries to deflect the boat to one side or the other (and backwards a bit), but the rudder forces the boat to move forwards instead (if the boat didn't have a flat stern, it might move backwards, too).
This is how we sailed around the world, back in the day.
Not really.
The physics of sailing upwind is completely different to a sail working before the wind as shown here.
A sail which can go upwind must be able to form a tear shaped cross section just like the wing of an airplane. It is this shape which generates the forward moving force, as well as a lot of sideways moving force - the drift. The drift is counteracted somewhat by the rudder but most of it is canceled by the fin or the keel. But nevertheless, the boat is pulled by the wind approaching the sail from the front and the airflow across the the sail generates the forward force. But it is not pushed by some deflected wind from the back.
The beautiful old sail boats you might be thinking of (such as the one Columbus used) really could not do much more then sail before the wind (downwind). If they needed to go against the wind, they were pretty much out of luck and had to wait until the wind shifted.
SCIENCE!!!! :))) So cool!!!! THX 4 sharing this with us Mr. Yeany. :)
Does the flat surface being close to the fan have anything to do with it going sideways. If it were farther away and could still deflect it might go more backwards as it might not have to overcome as much foward air pressure from the fan. There is probably and optimal distance. At which point you can test materials in a small degree by finding different ideal distances. Although it's probably not complicated enough to fully go over what is happening.
so since some of the air is redirected back through the fan with the cardboard sail, would the back wards cardboard sail not have as much air that redirected? Does the back wards cardboard sail go faster than the traditional looking cardboard sail? Great videos!!!
what if you attach a tube on back of the fan, and the tube makes a 180 degree u turn facing front? that would remove the negative effect.
With the cup "sail", if you where to flip the fan around so it pushes air backward, wouldn't this create a lower pressure in the cup and cause less air to being pushed backwards.
Could a lateen sail be used instead of a square rig sail? Could a combination of tacking and jibing achieve a faster overall journey (than driving sails) when used in conjunction with the fan motor?
I tackled this square sail setup again because the fan cart is a popular item in science classrooms and I wasn't happy with how I left it in the last video. I used to do some sailing when I was younger and really would like to try some future demonstrations with the lateen sail and take a look at some of the basic science behind it.
Great follow-up video. When you say 'how a sail works', will you be looking at the Bernoulli effect, and sailing into the wind, tacking etc.?
I hope to, however, I have some other ideas that I need to get to first
Great -- I'm sure getting there will be both fun and educational!
Another Freediver Agreed that this would be great! The "wing" effect of a Marconi-rig will work differently than a square-rig.. especially at different points of sail! But great videos all around Mr. Yeah!
i was wondering if you added a curved tube pointing backwards and then Y'ed the tubes pointing backwards
Here us my take on why this works. First of all, air molecules don't "bounce" off surfaces like some have suggested. They create flow fields and pressure gradients. If you assume that all the force acting on the propeller is in the opposite direction of the air flow it generates, it still wouldn't matter if all the air was redirected backwards from the sail, the forces would cancel. The part that is being neglected is the propeller. The propeller isn't just colliding with the air causing it to flow, the rotation and shape of the blades cause a pressure differential (Bernoulli effect) that causes the air to flow and give it linear kinetic energy. Part of the force acting on the propeller is opposite the direction of the air, but the Bernouli part is (at least partially) counter the rotational moment of the blade. For this reason, the linear force acting on the propeller could be smaller than the force pushing on the sail. You can think of the sail in terms of drag force. In this case, the larger the sail, the larger the drag force at least until you reach the maximum force produced by the air flow. Newton's laws are not violated.
You make me wish I became a high school science teacher! Great videos!
Can you use PVC pipe and suck the air from top and to the sail ? i Think its going to work. or use U shape PVC pipe and suck the air from top of the sail facing forward and blowing it to the sail. ?
@8:30 - I believe the boat is not going forward based on the fan hitting the sail....and the loss of rotational force is not due to the rudder entirely, but rather the vibration of the motor is directly influencing the rudder in the water, which causes the rudder to act as a moving "fin." Take the fan blades and sail completely off and run just the motor with the rudder, I'll bet you get movement.
thank you so much for this. very good work.
I always think about flight, I’ve built many full size airplanes. But the idea of an air filled parachute has been with me since I was a kid. I had a powered paraglider for a bit, The difference between a paraglider and a parachute is that a parachutes has pores in it. The air goes through a parachute. A paraglider if you blow on it, you can’t force and air through, it’s an inflatable wing. But my dream was to make an old school parachute out of paraglider fabric…. Non pourus fabric. (A sail). You have a giant parabolic surface. Then you blow air up into it. The thrust comes from it blowing back (like a reverse thruster). You’d have the worlds safest aircraft, If it quit, you’d just float down. Thing is, it would also be the worlds least efficient aircraft.
if the net force is 0. does it come to a stop faster if when you push it because the fan adds stability through friction or something. I'd really like to see that :)
I tried it after reading your comment, I didn't see any difference
Two things I noticed.
1.) the first sail was pretty close to the same area as the sweped disc of the propeller. This could be one reason the reactions canceled each other out.
The second thing was that the first sail was also very close to the propeller.
Two possible experiments.
1.) put the original sail at least one fan blade diameter ahead of the fan.
2.) make a contoured sail that has the same area as the original sail, and place it at least one fan-blade diameter ahead of the fan.
Another experiment is to put the larger contoured sail at least one fan-blade diameter in front of the fan.
See if it Propels the cart faster than the new, smaller contoured sail.
I predict that it will.
wondering what the track's name at 0:00 ？
This reminds me of a question I had awhile ago.
If a space ship had uneven thrust behind it and started spinning, could Gyros keep it going straight if they were strong enough? The rudder causing that to travel straight reminds me of that question. You were actually able to get it to go straight by a completely different mechanic which is amazing to me. I guess that would be sort of like the tail rotor of a helicopter.
i'd say yes, the gyros can stabilize the spacecraft
Yes, but would it keep it going straight or would you drift sideways while traveling?
HI Joel, good question, my guess if it is oriented correctly the gyro should be able to straighten out the movement. I'm not sure when I will get to it but I've wanted to do a segment on gyroscopes and I will add that to try in the segment.
That would be awesome
I think this would work for a while.
The gyro works by having a spinning mass which is carefully controlled to take advantage of Newton's 3rd Law - for every action, there is an equal and opposite reaction. By applying a torque (rotational force) on the gyro (either through a motor or friction), an equal and opposite torque is experienced by the rest of the space ship.
The imbalance in thrust creates a torque, which will cause the ship to turn. The ship can apply a countering torque on the gyro, such that instead of the ship turning, the gyro turns instead... up to a limit.
The turning isn't adding rotational speed, but rotational acceleration. In order to counter the imbalanced thrust, you have to keep accelerating the gyro. Eventually, this will induce centripetal forces inside the material of the gyro which tear it apart.
Would multiple motors (and fans) increase the speed?
It still doesn't make sense to me how a curved sail is able to produce thrust in this scenario. Because if you picture it, the fan produces thrust by spinning curved blades that push off the air perpendicularly to the blade movement and that in turn pushes the blade in the opposite direction. But then the curved sail produces thrust by redirecting the air which is essentially pushing off the air like the blade did. And the part that baffles me is that the air got momentum from the fan and then it transfers that momentum to the sail. So how can the sail win over the fan? I picture the sail like a mirror reflecting the light; maybe a corner reflector would be more analogous.
Teaching science done right :-)
how about you do the reverse thruster method but put on another fan facing in the opposite direction and maybe make the closed end of the tube a cone
interesting, I want to try a video on reverse thrust.
I still don't understand how does it move forward. How would U-shaped blower move?
So if this worked couldn't we do the same thing with a "Solar Sail" ?
You could reach some pretty high speeds and you'd never get stuck/stranded somewhere with insufficient light to drive the sail.
instead of cylinder... can we try a parabolic or hyperbolic sail
Spinning because of torque, your prop might be a little pointed up and that would cause p factor. That uneven air, is known as (p factor). When you take a prop. If it’s perfectly level both the up and down blades are at the same angle. If you put it at an angle the descending blade catches more air. If you take your hands and make a prop with them. Them tilt the “prop” up, you’ll see the angle actually changes.
where can I get the motor and rig parts?
the action lab needs to remake his video by watching this
Love this guy!
I'm guessing the cylinder will work you will need too cut holes or notches on the end to give the air someplace to go.
That’s why sailboats have keels they take any energy that’s put into the sales that’s not at the right angle and forces some of that energy in the direction you wanna go. Also helps keep the boat upright but that’s somewhat obvious.
Loved your smoke generator! A bit of Chemistry in the Physics experiments! But ammonia and HCl would not be a good alternative in front of a class, I think. Lycopodium is messy. A smoke machine would be a safer alternative or a ultrasonic humidifier fog generator.
Great lesson.tks.
Greetings from São Paulo
That was so awesome! Thanks!
isolate the fan with its own air intake separate from the air being pushed back from the curved sail to prevent recirculation . the fan should have a tube over it extended past the back of the boat so suck in clean air and point the other end directly to the sail. itll move so much faster.
If you add a pipe behind the fan so that it can't reuse any of the air that comes from the sail, that might be more effective. Maybe?
But how did you empty the water from the table?
I used a siphon into smaller buckets
i have doubts as your kart is too bulky ... i know for a fact that the forces cancel out because you cant auto generate forces from nothing and get a positive outcome
on the water, it spins because motor turning to one side. Airplanes with one motor, they have same problem it called "thrust angle".
you can make video about that cause its rly interesting
But this would mean the spin is always in the same direction isn't it?
Hi :) your experiment is really interesting. I am bit into sailing so I'd like to see the effects of blowing into your own sail using a modern sail concept :)
I have some other videos I want to get to but I plan on trying some more on the behavior of a regular sail
You should be able to improve performance beyond what fan alone can do. Fan moves smaller amount of air at high velocity. F = MV is the force. But P = MV^2/2 (power to operate fan). If airfoil can convert small M large V to large M small V efficiently, then force can be increased for given power. This is why helicopters use large, slow-turning rotor (for static left), and airplanes use smaller propellers turning fast (for cruise speed). The airplane wing converts some of the "speed force" to a larger "lift force". Properly-designed "wing sail" should be able to do the same. Try first blowing across the curved sail from the side. You should be able to get faster boat versus blowing out the back with fan only.
rotation of propeller is causing issues.
have two propellers spinning opposite directions to counteract
+Bruce Yeany Nice set of vids but what you don't explain here is that sails work as wings and therefore it is the depression caused by the sail and not the wind pushing into the sail that makes the boat go forward. Thanks for all the others vids :)
Thanks Adrien, I hope to tackle more on the behavior of sails in another video
Thank you for taking time to explore the comments and suggestions we contributed from the earlier video on this subject. You mentioned in this video that you believe you don't understand how sails work. If you will allow me a moment, we can explore this together -- and please feel free to correct me when my "science" strays or fails me.
In my "armchair physics mind," I see no difference between the sail and the boat itself. Air is a thinner medium than water, but the same principles apply. In essence, the sail "floats" on the air at a perpendicular to the boat floating on the water.
First, let's consider the boat. It floats because the area of the boat is great enough to disperse the downward force of gravity exerted on the boat's mass and displace an amount of water sufficient to offset that downward force. The boat moves with the water current because the force of the current applied to the boat is greater than the force of the inertia-at-rest applied to the boat.
Now let's consider the sail. In order for the sail to work, there must be sufficient area of sail-cloth (we'll come back to this in a moment), to overcome the force of the boat's inertia-at-rest (rather than gravity, per se) and displace an amount of air (behind the sail) sufficient to overcome that force. The boat moves with the air current because the force of the current (captured by the "billowiness" of the sail, and thereby multiplied) applied on the boat is greater than the force of the inertia-at-rest applied to the boat. The larger the surface area of sail provided and the more billowy the sail (without reaching the point of diminishing return), the more the air current can be captured and directed to help propel the boat in the desired direction.
Note that the last sentence reads "...in the desired direction." A good sailor can tack into the oncoming wind and use the position of the sail in concert with the rudder to move the boat forward at a vector to that wind.
Now let's go back to the issue of the area of the sail-cloth. Before self-propelled ocean-going vessels, there were the tall-masted ships. As these ships demonstrate, the area of sail-cloth does not have to be provided in one large sail. Instead, the effect is multiplied by providing numerous sails of various strategic sizes, strategically placed in order to optimize wind capture and direct the harnessed energy.
Does this explanation make sense to you? Have I missed (or misstated) anything?
Sorry, Sir. There is no such a thing like "force of boat's inertia-at-rest" .Inertia is not a force. The thinnest, smallest force will accelerate ( move) a giant body ( a rock, ship , or even a planet ), if there is no friction.
Inertia means that a the movement of body along a straight line (constant velocity) is a state as "natural" as the state of a resting body ( "quiete"); no cause, no force is necessary for both states. Galileo understand that the uniform motion in a straight line has the same status as the uniform motion in a right line. NO EXPLANATION is needed.
As Newton stated: Every body perseveres in its state of rest, or of uniform motion in a right line, unless it is compelled to change that state by forces impressed thereon.
The point is : Inertia is not a CAUSE. FORCE is a CAUSE.
When you love your job so much you stay after hours to keep doing it
When I first see the words "Fan Cart" My mind turns into a kid again and giggles.
hi Where can i find a small motor?
I've had students take them out of broken toys, or you can find them online, do a search for toy project motors,
Great video! I really enjoyed this:D
I remember that MythBusters once proved that you can blow your own sail;
I think their explanation had something to do with certain sails being unable to absorb all the wind, although I think that this was just an initial guess.
Good job. Pretty scientific! You falsified (in the good way) my concern about angular momentum and proved me wrong. Hope this inspire kids to follow your steps (or at least know how to test if something is true or not based on evidence!!)
Cheers!
This guy is pretty cool.
Dear Mr Yeany, thank you for your excellent lessons! By the way, you have just broke the third Newton's law, have you noticed? And rightly so, that should have happened a long time ago.
The point is you get more force because the sail amplifies the efficiency. Regardless of the initial force being in the wrong direction.
Great video!!
what you could do when on the pond is have a second fan blowing to the side so the net force is at a 45' angle or so to the boat and so the boat goes on a circle
I'll bet if you add a shroud around the fan so it pulls the air from further back you'll get more thrust
there are only two force on the boat.
1. reaction force to fan pushing the wind (push boat backward)
2. force that wind hit on the sail (push boat forward)
the fact that boat going forward means that wind going forward is smaller than wind going backward in the momentum perspective.
it's like ball thrown to wall bounce off more strongly. this is wired.
the air is fluid not solid. maybe this is the reason.
I want to know why backward wind is stronger
All things being equal this should not work, which means they are not equal. Some of the energy of the fan must be applied up and or down and not straight back. This leaves room for the energy of the sail pushing back to overtake the energy of the fan pushing forward. Causing a net force from the sail (pushing back causing it to go forward)
The fan only doesn't work with flat sails because a lot of the energy gets diverted to the side instead of backward losing a lot of the forward force. The fan is always causing a net energy forward or this would not work.
so ut would work in the cartoons?
What is life, if not a cartoon with better physics?
I mean, it's similar to just running a fan backwards at this point, but less efficient. Or also, running a tube from the front of the fan around back again to propel it. So the florida janitor would have been better off just aiming the leaf blower behind him.
with the cup sail, the fan is interrupting the reverse thrust
Thank you very much Mr Bruce
your videos are very interesting but I don't understand English
please you can translate your videos in french and thank you again for all your efforts
please show and angled sail with a rudder applying force in the opposite direction. both with wind from behind the sail and wind from the front. and cover "sailing into the wind."
thanks from a subscriber.
Hi Brian, I have some ideas for it and I do want to tackle the behavior of traditional sails. I have too many plans and not enough time to get to them all.
thanks for the reply! Maybe one day! I will keep watching. Thank you for showing people science in action.
Very cool
Let’s try y with a miniature umbrella! Maybe will moving faster, I’m very interested 🙄
Вы сделали из лодки вертолет )). Вам надо было для эксперимента включить реверс оборотов и посмотреть , начнет ли лодка вращаться в обратном направлении ?
Making science fun
This isn't science, this is magic
lovely
Bruce you never have explained how rockets can work in a vacuum, based on Newton's third law. Let me recant ,it's been explained multiple times ,but how could we demonstrate this?
johnathan bowman - Newton's 3rd Law states that when one body applies force to another body, an equivalent force is applied back to the first body. A rocket combusts fuel, which reacts and rapidly expands. This fuel's expansion is directed in one direction, so all of the force applied to the fuel is in that one direction. The fuel (or rather exhaust at this point) then equivalently exerts a force back upon the rocket it is being expelled out of, driving the rocket forward. This reaction works exactly the same in or out of a vacuum. The major difference in a vacuum is that you don't have air resistance, which actually slows the rocket down more than speeds it up. While it could provide more for the exhaust to push against, it exerts a great amount of friction against the rocket. This is why rockets are more efficient in a vacuum. There isn't a very easy way to test this on a small scale, but for something similar, Cody's Lab has a few videos of explosions in a vacuum chamber showing that the velocity of the debris is higher in the vacuum than in atmosphere.
Am I the only one who keeps reading the title as "fart can" by accident? lol
Try Dyson's blameless fan or some cheap imitation of it. You can find it for up to $5 in a local dollar store.
So perfect!!!!!!
I love your videos Bruce, but as an adult now ,I have questions about some of the science I was taught in school .That's why I keep asking you about this particular topic . I would appreciate it if you would try to think of an experiment that would demonstrate just exactly how a rocket could work, in a huge infant vacuum chamber . Look into it. This is supposed to be science right, don't call me an idiot for asking questions as a lot of you guys do for this particular thing ,in the comments . Not you Bruce, you're a good guy. Thanks in advance for anything that you could come up with for a demonstration.
johnathan bowman - May I ask what it is about the workings of a rocket in a vacuum as opposed to an atmosphere that you're wondering about?
GuyNamedSean It's not necessarily a rocket working in a vacuum, that I'm concerned with, it is the very nature of the vacuum of space. I mean doesn't a vacuum require a vacuum chamber? I would be very curious to know if a very small rocket ,like a bottle rocket, (firework) would function properly in the huge vacuum chamber that NASA has. This is the only chamber that I can think of that's large enough to even come close to testing this thing that were told about space, being an infinite, ever-expanding vacuum. I know that people like the Mythbusters have tested this on National Television but their vacuum chamber was so small that I would have to be inclined to think that the rocket was actually pushing on the sides of the chamber. I guess your next question is why would I wonder this. And my answer would be money .NASA takes 10 million dollars a day from the taxpayers of the United States, for a small group of people to go to places that no one else can. It's a pretty good scam if you think about it.
Johnathan bowman, it's a good problem and I've taken a look at how to prove it, the problem comes back to building a large enough vacuum chamber. Something I've wanted to do but has been cost prohibitive so far. I will keep looking because there are some other experiments I want to try also.
johnathan bowman - Did you read my reply to your other comment? It goes into some detail about your inquiry as far as my understanding of it goes. I'll stress that I'm not specifically a physics student, though I do take time to study astronomy, cosmology, and rocketry in my free time.
Bruce Yeany I appreciate you looking at it Bruce, with an open mind, thank you. After all ,it is supposed to be science ,right?
Got this recommended after Action Lab's video
Ok, now im intrigued as to how he oroduced tue smoke, first with two liguuds, then what appeared to be tissue soaked with something. Cool as ever.
Well done Bruce! My suggestions: use an EDF (electric ducted fan) instead of a propeller, smoke instead of powder, and light as I did in my Coanda effect video ruclips.net/video/aF92B6Gon3M/видео.html @1:35 in a dark room with a spotlight coming from behind, shining towards the lens. A visible airflow can explain a lot.
Hello Giesbert, thank you, great job on the Coanda effect, something I played a round with a bit but your method is much more direct than mine. I appreciate the comments and will keep them in mind for a couple future ideas I want to try .