Risking My Life To Settle A Physics Debate

Birt 29 maí 2021
Everyone will say this craft breaks the laws of physics. This video is sponsored by Kiwico, For 50% off your first month of any subscription crate from KiwiCo (available in 40 countries!) head to www.kiwico.com/Veritasium50

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A HUGE thanks to Rick and Neil for letting me drive Blackbird. Check out Rick's ISmem Channel for more in depth videos and explanations on going faster than the wind downwind -- ve42.co/Rick

Gene Nagata made the shoot possible. If you’re a video nerd like me, check out his channel, Potato Jet: ismem.infof... .

Xyla Foxlin for made the model cart used in this video. Xyla builds amazing things like rockets and canoes, check it out! ismem.info

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References
Jack Goodman's ISmem video -- ve42.co/Goodman
Rick's treadmill footage -- ve42.co/Treadmill
Rick's multiple explanations of how Blackbird works -- ve42.co/DDWFTTW
Forum discussions -- ve42.co/forum Blog -- ve42.co/blog1 and retraction ve42.co/BlogRetraction

Gaunaa, M., Øye, S., \u0026 Mikkelsen, R. F. (2009). Theory and design of flow driven vehicles using rotors for energy conversion. In EWEC 2009 Proceedings online EWEC

Md. Sadak Ali Khan, Syed Ali Sufiyan, Jibu Thomas George, Md. Nizamuddin Ahmed. Analysis of Down-Wind Propeller Vehicle. International Journal of Scientific and Research Publications, 3, 4. (April 2013) ISSN 2250-3153. (www.ijsrp.org)

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Special thanks to Patreon supporters: Bill Linder, Paul Peijzel, Crated Comments, Anna, Mac Malkawi, Michael Schneider, Oleksii Leonov, Jim Osmun, Tyson McDowell, Ludovic Robillard, Jim buckmaster, fanime96, Juan Benet, Ruslan Khroma, Robert Blum, Richard Sundvall, Lee Redden, Vincent, Marinus Kuivenhoven, Alfred Wallace, Arjun Chakroborty, Joar Wandborg, Clayton Greenwell, Pindex, Michael Krugman, Cy 'kkm' K'Nelson, Sam Lutfi, Ron Neal

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Thanks to James Lincoln for building the initial prototypes for a model blackbird.

Written by Derek Muller, James Lincoln, and Petr Lebedev
Animation by Mike Radjabov and Iván Tello
Filmed by Gene Nagata, Derek Muller, Trenton Oliver, AJ Fillo and Emily Zhang
Edited by Trenton Oliver
Music from Epidemic Sound epidemicsound.com
Additional video supplied by Getty Images
Produced by AJ Fillo

Ummæli

  • If you want more detail on the explanation here it is: 1. The car is powered only by the wind. There is no motor or batteries of any kind. 2. The propeller does NOT spin like a windmill. The wind does NOT push it and make it turn. 3. Instead the wheels are geared to the propeller to turn it the opposite way, like a fan, so it pushes air backwards. 4. To start the vehicle the wind simply pushes on the whole vehicle (like a block of styrofoam) and gets it moving. 5. The wheels are turning so they turn the propeller in the opposite direction to how the wind is pushing it. 6. The prop is pushing air back so air pushes the prop forwards, accelerating the car. 7. Once you get up to wind speed there is no apparent wind on the vehicle. If the prop were spun like a windmill this would mean no more thrust. But, since the prop is operating like a fan, it still accelerates air backwards, generating thrust. 8. You can go faster than wind speed continuously because even when going faster than the wind, the prop can still accelerate air backwards (in the car's frame of reference) generating thrust. In a stationary frame of reference you would see that the wind behind the propellor is slower than the surrounding air. So it's clear that the energy is coming from the wind. FAQ: If power is coming from the wheels to turn the prop, why doesn't that slow down the wheels more than it gets the prop to push back? A: Because the wheels are moving over the ground much faster than the prop is moving through the air (because there's a tailwind). Example: Let's say the car is going 12m/s in a 10m/s tailwind, so faster than the wind (note the prop will be moving through an apparent headwind of 2m/s). Power = Force x Velocity Let's say the chain applies a drag force of 100N on the wheels to drive the prop. This means we're taking power from the wheels = FxV = 100N x 12m/s = 1200W If we apply this power to the fan, it can create a force of F = P/V = 1200W / 2m/s = 600N Admittedly I've assumed no losses, but even if we waste half the power, we'd still get 300N of thrust which is more than the 100N of drag the prop adds to the wheels. The key is that we're harvesting power at higher speed, lower force, and deploying it at lower speed, higher force (which is only possible because we have a tailwind - in still air this wouldn't work because the relative velocity of the wheels over the ground would be exactly the same as the relative velocity of the prop through the air).

    • I'm mind blown

    • @дмитрий иванов >> How does the structure behave in calm weather? It just sits still in no wind. Or if you prefer - it can go 3X wind speed in 0 wind. :)

    • @eyytee "MIT aerodynamicist Mark Drela : "In my view, the most closely controlled and unambiguous DDWFTTW demo is the cart climbing up the tilted treadmill." in the article: "What I’ve Learned About Wind Carts" by Mark Frauenfelder" Here's what I think "could" also work, though some people would still think that there are too many potentially hidden energy imputs being applied to the vehicle. Use the treadmill apparatus, sure, but in a different way, completely level. Just to prevent the vehicle from rolling forward, at first, when a fan starts to apply wind velocity/pressure from behind (I mean there is only a limited amount of runway on a treadmill). At some point as the fan is being ramped up in output air velocity/pressure, the vehicle is going to start rolling forward. At this very precise moment, stop the fan speed increase and hold it at that point (showing the audience that the fan is no longer being ramped up). Now also at this very precise moment start the treadmill to keep the vehicle in the center, by gradually ramping up the belt backward rotation in unison with the vehicle's tendency (now that the wind is pushing it forward) to NOT roll forward. At a very precise belt velocity, we will witness that the vehicle is not continually accelerating indefinitely, that the fan is set at a very precise velocity. We will be able to measure and record the vehicle speed in relation to the belt's m/s. We will be able to measure and record the velocity of the wind in m/s and compare the two. Simple. But, again, some people will think there is hidden inputs. This is why a tunnel/pipe with nothing but a fan, a vehicle on a rail (keeping it straight and giving it the wheel to ground contact required for rotation) would/should sooth these people's suspicions.

    • @Fred Meister look up mechanical doping in cycle racing then tell me he checked properly, science-hating crackpot.

    • It still does not explain why the speed of the prop is accelerating instead of decelerating when the vehicle is slowed down.

  • I till think hamsters were involved!😆

  • Need a sail in front of the prop to get is to start. Then disengage when at speed

  • I think it needs to be done again except this time release Smoke on the blades and let's see what kind of vortexes we would get before and after the blade .

  • i think this would be useful for trucks in windy roads, to save fuel.

  • People arguing wether or not the earth is flat. It’s not flat my dudes,

  • The science is cool but the video was edited like a reality show and I hated it. I watch ISmem specifically to get away from this type of show. Don't try to create suspense and waste our time dangling the results, just tell us the story like it happened.

  • I wonder how the ratios of force would behave on mars, maybe we could bring some pirate propeller martian sailors.

  • Derek... you're credible right up until your "climate alarmist" lies. That soohistry was so blatant and non scientific... you proved yourself an indoctrinated funding fiend more than an objective thinker. Shame on you.

  • Fake nEwS

  • this is freaking awesome but what kind of helmet is that?

  • My first thought was. If you can put the prop on a rotating tower that still receives drive from the wheels. Could you drive the car in any direction? And the answer of course is no as you cannot drive sideways to the wind. It is a car where the wheels drive the fan and the fan pushes the car, so the fan is limited to pointing thrust in a mainly rearward direction. It is a fascinating physics experiment, but a useless engineering concept (from a modern life point of view), the downwind only vehicle.

    • Yes, you could allow the nacelle to rotate and you could go faster than the wind in any direction.

  • so what is the tip speed of the propelar and the gear ratio at 10mph?

  • Not buy gears? Connected to wheels

  • I kind of liken it to a bicycle. If a kid puts all his energy into running, and the same kid puts all his energy into riding a bike. The kid will go faster on the bicycle.

  • Great

  • The way I understand it while once the cart at the speed of the wind and the blades are counter spinning against the wind creating a bubble per say to push the cart faster. (I have been thinking about how to write this)

    • There is a common misconception that the propeller creates a sort of air-buffer for the tail wind to push against. But the reality is that the tailwind is not pushing it when it's going faster than the wind. The propeller is simply acting in an advantageous medium - one that is moving slower relative to the cart than the cart is moving relative to the ground.

  • the final explanation is just music to my ears 😁👏🏻👏🏻👌🏻👌🏻

  • Absolutely fantastic!

  • Nope. Still doesn’t make sense. What is pushing the vehicle? Answer - the wind (until the vehicle reaches the same speed as the wind) - which can’t be right. Nothing ( even a gallon) travels along at the same speed as the actually wind pushing it.. What’s driving the wheels? Answer - the propeller What’s driving the propeller? Answer - the wheels And all that also overcomes all the inherent friction in the running gear (wheels, bearings etc) I’m no physics major I admit, but this just doesn’t work for me. One of the internet geniuses in the comments below made a comment that is uses the difference between wind speed and ground speed, but failed to explain how it worked when the vehicle was travelling when both were equal.. and given the vehicle had to be travelling at that speed at some point to then go faster than wind speed, this statement failed. Not a believer I’m afraid. Sorry.

    • // "One of the internet geniuses in the comments below made a comment that is uses the difference between wind speed and ground speed, but failed to explain how it worked when the vehicle was travelling when both were equal."// You're confusing 'relative windspeed' with 'true windspeed'. The difference between the *true* wind and the ground never equalizes (as long as the wind keeps blowing). Yes, there is no relative wind across the chassis of the vehicle at exactly windspeed, but the wind itself didn't stop blowing. The Blackbird harvests energy, not from the wind across itself, but from the true wind across the ground.

  • Very clever! ...um.... I wonder if I would be wrong in saying that some of the increased prop velocity is transferred (or blead off) by a prop-shaft which is used to drive the wheels, thereby pushing the kart faster than it would normally go when running before the wind. I was most intrigued to see how, the Kart outran the actual speed of the wind. When the ribbon dropped it obviously reached parity but then it re the kart accelerated to outstrip the apparent wind as the tell tails so revealed... most interesting.

  • This is counter-intuitive, of course, but a sailor does understand one thing: The blades on the prop, have a very different Apparent Wind than the vehicle itself. The vehicle is going downwind, but the prop is sailing on a broad reach (only slightly downwind). What I understand is that Bernoulli effect on the prop blades does put lift on the blades, driving them to rotate. The blades are not a sail to push the vehicle, they are a sail to drive the wheels. The velocity of the blades spinning adds to the velocity of the wind. The blades are traveling closer and closer to perpendicular to the wind as the vehicle goes far beyond wind speed and the blades spin ever faster. As many have observed, the explanation of two boats sailing on a broad reach on a cylindrical sea really helps one make the connection to how the props work on the propeller shaft. What I did not know is that sailing a broad reach zig-zag will let you reach your destination faster than running downwind. Faster than the wind itself, with a well-designed sailboat.

    • >> Bernoulli effect on the prop blades does put lift on the blades, driving them to rotate. The blades are not a sail to push the vehicle, they are a sail to drive the wheels. Nope. The wheels are driving the propeller. We have a ratchet on the axle that prevents the propeller from driving the wheels.

    • I need to edit what I wrote. As someone else above me wrote, as the vehicle exceeds the wind speed, the prop blades move from broad reach to close reach. If a sailboat can tack upwind, there's no reason the propeller blades cannot do the same thing.

  • Way too long. Too much drama. And why are you driving it at all?

  • By this logic, couldn’t an airplane be built with 4 props? 2 of the props act like the wheels did in this video, the other two provide thrust, and voila, once you get up into the jet stream you don’t have to pay for fuel anymore.

    • Yes, that would work fine - as long as two of the props were in the jet stream and the other two were outside of the jet stream.

  • I have to ask... what about boats with the modern sail designs, like the multiple helixes around the mast - etc.

  • I am really curious to know what happens if we theoretically let the blackbird keep running downwind and so that it keeps retarding the air behind it upto 0 speed, will there be a vaccum creation behind the propeller, and if that happens what will follow next? 😥

  • Surely, if they can get 2.8 times the wind speed, then it is not a matter of "stealing" speed from the wind directly behind the craft? Because that has a limit as to how much can be stolen (wind speed).

    • We're taking energy from the wind and slowing the wind down in the process.

  • It took a while for you to explain it well enough for to no longer misunderstand. Well done. I still don’t understand it enough to replicate it, but I do know that it works. Which means that if I did want to do it myself, I would keep going until I got it right

  • Soo what are the implications here?

  • Could you drive against the wind with it?

  • This is not a valid test IMO .. the vehicle is being powered by a mechanical devise (Fan) and the fan is being powered by rotation of a wheel and the wheel is not powered by wind .. the wheel is powered by inertia of the vehicle and in turn applying thrust witch then increases the inertia more applying more thrust … this is definition of mechanical propulsion … so no they didn’t break any laws of physics here … if you try to accomplish this test without any power adders that are operated by anything other than wind I’d be happy to watch again !

    • >> the wheel is powered by inertia of the vehicle Nope. We are definitely not making use of inertia. >> so no they didn’t break any laws of physics here We try to make that point very clear. >> if you try to accomplish this test without any power adders that are operated by anything other than wind I’d be happy to watch again ! All we have here is wind and ground. The air is moving relative to the ground. You can decide whether it's the air or the ground that's moving, but that's all there is.

  • can't this be used as perpetual motion? I mean, after a while in the wind, the propeller keeps spinning which causes the wheels to turn which causes the propeller to spin... can someone explain?

    • ​@eyytee oh I didn't notice the pinned comment, it actually answers my question at the end of the explanation, thank you!

    • Read the pinned comment.

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  • Makes sense

  • It is bizarre to me that supposed physics professors couldn't get this. Would I have thought it up myself? No. But once explained it just seems so like... "duh!"

  • Please someone respond and tell me if I’m wrong. Isn’t the easiest explanation for this: 10mph winds 👉🏻 Fan pushes back with 10mph winds 👈🏻 10+10=20 ?? Very simplified with hypothetical numbers, but in principle isn’t it just that easy ??

    • @m pugh Some of the best explanations and animations are in the video you are commenting on. An important thing to remember is that the wheels turn the rotor and rotor never turns the wheels.

    • @John Borton how it uses the wind**

    • @John Borton do explain how it uses the wing and not the and glue of air flow OPPOSITE to the wind, over the fans ?? Ps I may seem cocky, but I’m trying to improve on my basic knowledge by being corrected as opposed to just asking. I find details easier to absorb this way

    • @m pugh Nope. The Blackbird is totally wind powered. The wind IS the propulsion.

    • @John Borton maybe I made it a little too confusing by making them the same number..... You don’t have to harvest the first ten at all.....you are not using the wind as propulsion.....you are using lift from a propellor......you are just pushing against the wind. If you got people to push that car up to 10mph with 1mph winds it would likely hold its speed longer than expected......almost perpetually.....though I highly doubt literal perpetual motion 🤷🏻‍♂️

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  • Tangentially, I thought the "wind moves in over the curved side of a wing more quickly" explanation for lift was wrong!

    • >> explanation for lift was wrong! Where specifically did you see an incorrect explanation of lift?

  • now put it on a boat

  • Any potential maritime applications here? If containerships could go straight, rather than tack, and faster than the wind, they might consider something like this, no?

  • no lo hacen bien

  • What would happen if you tried this with light? Light sails making up a propeller? Where does it breakdown and fail?

  • Now... can you use this for light-sail? That would make you go faster than light

  • can i install this on my prius

  • I feel more experiment should be done on this... There is an equation hiding somewhere that should show the relationship between the wind speed and the maximum speed the vehicle can attain, all things being equal.

    • @eyytee Yes, but it won't accelerate indefinitely as you know.

    • @Great Okamonu Google "NALSA downwind record" and look at their rules and the observer report. It was accelerating while going 2.8 x windspeed.

    • @eyytee nice, one parameter was not addressed in the experiment though, i don't think it was stated if the vehicle kept accelerating after it beat the wind speed or stopped accelerating.

    • max_speed = wind_speed / (1 - overall_efficiency)

  • This is the most unscientific experiment I've seen in a while. They either need a calibrated speedo on the cart and a calibrated anemometer on the ground, or two identical vehicles, one with change connected, the other not. Mr Veritasium has failed his usual scientific standards here.

  • Seems the purpose of the video is just to create comments. You are missing a lot of explanations in the video, how can we guess all without all the information? Also .. how will the slower wind create Low Pressure? And Low Pressure behind the vehicle creates Drag, right? How does it start moving forward? Just the wind pushing the rotor? What about the friction of the wheels? Should be a freewheel somewhere between the rotor and the wheels, isn't it? And to pass from "wind speed" .. that acceleration .. your explanation .. what about the increasing drag ??? What about the RPMs of the Rotor ??????? Man, not really the purpose of the video .. just creates confusion and guessing, not the videos I use to see from you. Did you just find out that the videos with a lot of comments work better on youtube, I guess that one right??

  • Thats it. Thats how we can go near speed of light. Maybe even beat it.

  • This is very similar to my experiences on the highway when coming up behind a semi and getting into its slipstream as the truck travels forward. That unique area behind the truck creates a partial vacuum that then "sucks" my vehicle into it. In effect, the truck's energy starts pulling my vehicle forward--and I'm almost getting a free ride. Like an airplane's wing, the lower air pressure behind the truck is providing me additional pull (lift) to actually save on fuel usage. The physics are there. One just has to see it from a different viewpoint.

  • This is not the first time I have seen this, back in the 90's I read and article about a Mirror dingy (Red wing - due to the red sails) that had a propeller for a sail. The propeller was mounted on a Morris car rear axle. The article went on about the same Physics (and to be honest even after this video I still don't get it), used to move the dinghy. Sadly it apparently crashed when mooring onto the pontoon. I don't remember what happened after that. Over all interesting to see in practice what I read about many years ago. 👍

  • i dont get it. why is the prop rotating in the wrong direction as it should be?

    • Because you think is should be rotating in the wrong direction as it should be.

  • Just think of this as a entirely mechanical Ramjet engine

  • Hi Derek. I've been thinking about this, and I think that one way to get this to make sense is to first imagine a craft with a sail, which catches all the wind until the craft and the wind are moving at the same speed. *Then* you engage a gear which connects a propeller to the wheels which are already moving, but you then retract the sail. The craft has inertia, so for some time will continue moving at its speed given by the sail. But now it will also be propelled *extra* by that fan. How much faster will it now go? Well, that extra speed will be the same speed as the vehicle would go with a motorized fan on a windless day. I think. Big assumptions about friction notwithstanding.

    • But the Blackbird doesn't use stored inertia to accelerate (only wind power), so you're explanation might make sense to you, but it's wrong.

    • I recommend you all watching some Americas Cup videos!

  • “Then he called for lights and rushed in, and came trembling and fell down before Paul and Silas, and brought them out, and said, ‘Sirs, what must I do to be saved?’ They said, ‘Believe in the Lord Yahushua Christ, and you will be saved, and your household’” (Acts 16:29-31).

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  • BS

  • We know it went faster than the wind at ground level, what was the wind speed at the top of the rotor tip?

  • powering the propeller surely reduces the speed off the wheels by more than the benefit of the propeller

    • Tell me why you're stuck there. I'm confident we can get you over the hump if you're interested in understanding how this works.

    • @eyytee I think the bit i'm stuck on is "Let's say the chain applies a drag force of 100N on the wheels to drive the prop"

    • @Rick Cavallaro I just googled you - wow, thanks for replying!, very interesting vehicle. I'm still confused but I'll keep looking

    • "powering the propeller surely reduces the speed off the wheels by more than the benefit of the propeller" No it doesn't. See the example at the end of the pinned comment.

    • @Will Mason We're not exploiting the difference in wind speeds. We're exploiting the difference in speed of air vs. ground.

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  • Can Blackbird charges battery packs once it's faster than wind using turbines? I feel like doing so will sacrifice speed in return, making it slower and therefore not work.

  • your new thumbnail is dumb

  • I like many of your videos, but this is not possible what you say. This machine doesn't work

    • Derek is engaged in a $10,000 bet with a UCLA physics professor on that very topic. I'll be very happy to make that same bet with you. What do you say?

    • what about the air molecule that hit the front of the propeller?

  • There's NO WAY this works. You're completely glossing over the fact that when a sailboat is going faster than wind, they aren't going straight down wind. It can only achieve this at an angle. Another HUGE issue is that you can't take a geared propeller driven off of wheels on a vehicle being pushed by the wind, then somehow propel it faster than the wind that's pushing it. That would remove the force of the wind off of the vehicle, meaning nothing was pushing on it. The only way that "telltale" would possibly ever show backwards is when you're coasting and the wind has stopped. This entire thing is a scam.

    • @John Lord >> You can't move faster than the air you are harnessing the energy from. So sailboats, ice boats, and land yachts can't go faster than the wind? And they can't make downwind VMG faster than the wind? Is that honestly what you're trying to say!?

    • @John Lord >> are you SURE you want to pay off my car? I'm absolutely certain I want to take the bet with you for any amount you're comfortable with. Does this mean we're on?

    • @Rick Cavallaro I'm not a layman. I was in the Navy and understand quite well how both sails and propellers work both in the air and water. are you SURE you want to pay off my car? This is literally a perpetual motion machine. The wheels drive the propeller which moves the car which spins the wheels. Its trivial to prove how impossible this is in a simulation. Not only that, but i watched your video of the "scale model". It was obviously being pulled. Just the fact it travelled in a straight line on a street for that distance PROVES that. Are you trying to get grant money or something? You aren't the first people i've seen try silly pseudo-science. Another interesting tell is you originally hyped your vehicle as being able to travel UP wind, not down, which would be trivial. I'll also note that your treadmill test was invalid because you are harnessing the energy from the wheels so the apparent wind speed when the cart isn't actually moving will always be the same as a full tail-wind pushing the cart. It's not surprising you were able to move forward on the treadmill because the blade has the ability to exert forward momentum when the wind it's pushing against isn't the wind it's getting the energy from. This doesn't translate to your full-size vehicle because once you're moving as fast as the wind, there's nothing pushing you anymore. Nevermind the fact you'll never actually hit windspeed anyway because of parasitic loss. This isn't relativity or quantum mechanics. It's simple newtonian physics.

    • @eyytee that doesn't matter. It's not the propeller blades that are catching the wind. In this case, they are trying to somehow use them to push with. Saying "seems to violate the laws of physics but doesn't" doesn't make it so. You can't move faster than the air you are harnessing the energy from. It's quite easy to tack into the wind faster than the wind, but even in their examples where the two boats are spiraling the cylinder, their directional momentum in a straight line equaling the cylinder still won't be faster than the wind. It physically is impossible to do so.

    • "You're completely glossing over the fact that when a sailboat is going faster than wind, they aren't going straight down wind. It can only achieve this at an angle." The propeller blades are also moving at angle to the true wind.

  • DDWFTTW vehicles are fascinating. So are your explainations

  • derk.... are you related to Elon musk? your expressions and maneurs are the same

  • air power engine on a gearing system force multiplier.

  • I recommend you all watching some Americas Cup videos!

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  • "Risking my life" well then no one introduce this guy to things that are actually a risk or he'll instantly piss himself. That's a pretty funny exaggeration, you didn't come close to getting hurt. Same risk as an afternoon motorcycle ride lmao. come to think of it that thing could have fallen apart around you and you'd have been fine, judging by the construction of that thing and it's weight, or lack thereof.

    • How much do you suppose it weighs?

    • You are ridiculous. Clearly if he thought that loss of life was LIKELY, he wouldn't have done it. Doesn't change the fact the his life was at risk nonetheless. The propellors were clearly spinning fast enough to cause damage were it to hit his head. That's not even to me mention what could have happened if the vehicle fell apart at those speeds. He could have been hurt regardless. People die from much less.

  • I thought that this was settled years ago?

    • I thought so too. But right now there's a UCLA physics professor that bet Derek $10,000 that it can't work. I wish someone would offer me that same bet.

  • Now can we do this with a 'solar' wind? and how far could we be able to accelerate? (I know that it would crumble when the radiation/wind becomes too low to power things up... but how far is that? and at what speed?)

  • What is actually happening is that the fan moves part of the air backward while the overall time average wind relative to the car is still from behind. This is the reason why they used a tell tale and not a comparison with measured wind speed and directly clocked car speed.

  • Physics teachers are wrong about a lot of stuff, but then their job description isn't to understand novel physics, but to teach known physics to students. I think the right thing to do about something like this is to ask an actual working physicist specializing in e.g. aerodynamics or fluid physics or something. Someone who might write a quick paper on the subject (or more realistically, suggest it to one of their postgrad minions to do it for their Ph.D. dissertation.)

    • There is absolutely nothing novel about the physics or aerodynamic principles at work here. They're just applied in a counter-intuitive way. >> ask an actual working physicist specializing in e.g. aerodynamics Aerodynamicists and physicist are two different things. You could ask Mark Drela, the M.I.T. aero professor, and he'd tell you it works for precisely the reasons explained in this video. Or you could ask Alexander Kusenko, the U.C.L.A. physics professor, and he'd bet you $10,000 that it actually doesn't work at all.

  • It is NONSENSE !. It works for moments when the wind speed changes and inertia keeps the speed above the speed of the wind ! Don't believe crazy things.

    • Derek is engaged in a $10,000 bet with a UCLA physics professor on that very topic. I'll be very happy to make that same bet with you. What do you say?

  • Out of topic question: Imagine a car moving close to the lightspeed and on earth you have imaginary TV that shows image from the car in real-time, according to relativity you must see events in slow-motion, but what if you have the same TV inside the car and camera on earth?

  • If i had watched your videos back in school i would have killed it. I wish teachers were like you. I am sure many are, but i sure hope i had someone like you!

  • The Internet is a just a place where stupid people come together... Flat Earthers, Anti-Science, Anti-Vax, Basically any community of people who call others sheep.

  • No sailboat can sail with the wind at exactly the same speed as the wind. The wind is the theoretical max, but friction will always make the boat slower if sailing in the same direction as the wind.

    • When going at an angle to the wind, a sailboat can outrun the airmass in the downwind direction, and beat a floating balloon by tacking.

  • 4:27

  • 1. The "counterintuitive" comes from confusing speed & energy: energy is conserved, not speed 2. My visual explanation: a car without a prop "takes" energy from a certain volume e.g. 10 units of "wind" behind the car. With the prop, the car "takes" energy from a volume reaching further back, e.g. 12 cubic units of "wind". Why? The prop pushes against the air directly behind it (disregard the fact that it's moving), which makes the air even further push back in the opposite direction (with the wind). The net result is that more of the wind's volume (energy) is thus engaged in ("taken by") this local system.

    • The notion that the propeller creates a sort of air buffer so the wind has something to push against is a very common misconception. The wind from behind is not acting on the propeller. The propeller is winding its way through "new" air. But that "new" air is moving slower relative to the vehicle than the ground is. And that gives the propeller a proportionate advantage over the wheels.

    • make sense

  • Fast explanation: Its a warp bouble that increase the speen on the front while reducing the speed on the back, the diferential is what you got as extra speed over the wind speed

  • Wow what an Idea ! It's great marvelous.

  • Thought about the argument, and it can make sense due to the diagonal sail cutting into airflow coming from the front, and in doing so, being able to reduce drag from the front but maintaining a continuous push from the back. Would honestly have to actually calculate it but that’s how I understood it to make sense EDIT: Ok nvm looks like he explains his way of understanding it lol

  • Cool beans, but can we do it with light sails to go faster than light?

  • Now the tornado will never catch you!

  • Got to the bit where you make a comparison to sailboats not going faster than the wind speed....did you watch the americas cup?

    • Sailboats don't go directly downwind (parallel to the wind) faster than the wind speed. They can outrun the wind by tacking, as the video shows.

  • If Magellan knew this he would've been able to circumnavigate the globe faster.

    • Indeed. Magellan couldn't even sail upwind effectively since his boats were square rigged. But if he had one of those new America's Cup boats, he'd be doing 40 knots into the wind

  • That is an awesome machine and a really clever invention. The explanation that you slow down the wind behind you helped my understanding of it a lot. Using something thats slower than you and making it even slower to accelerate is really counterintuive and feels like it "should" violate some law of entropy, but the inventor just understood those better than a lot of people. Hats off.

  • cilinder earth is better than flat earth change my mind

  • "Please, be civil", he said. Actually this is a simple physics.

    • @Jim Baker Huh, I thought it was an aerospace versus civil engineering joke

    • Simple physics, but the intuition is really hard. Simple physics can be really difficult, when it goes against intuition.

  • So, this is breaking the laws without breaking it.

  • americans getting mindblown by basic physics

  • I didn't understand it.. please try a little more harder....

  • Saying that this defies the laws of physics is poor understanding of physics. It doesn't break conservation of energy nor conservation of momentum as the wind have practically infinite mass(as long as in winds...) and hence more momentum and energy than the car.

  • Flatearther be like, "see? told you Earth is not a ball". It's a cylinder, but the flat end of the cylinder.

  • As explained in the video, the dynamics or physics sounded reasonable to me, especially knowing that the rolling wheels are driving the prop like a fan. This was cool!

  • Oh that's cool, a transmedium interface vehicle. It uses the organized motion of the air and the stationary tendency of the ground, to introduce more disorder into the organized laminar motion of the air. I can't recall many mobile examples of apparatus that utilize ambient power without using a third input(sol). They're all stationary hydroturbine dams, tideharvest, windmills, waveharvest, solarcells, geotherm. It is still limited in output by the ambient differential of motion(fluid vs ground), and how much of this differential can be harvested by the apparatus. Let's attach an Angstro-Resonant Neutron-rich Annihilant-Powercell and experiment with the output and performance envelope.

  • Well I am happy, halfway through this video just after you mentioned that the blades are spinning backwards I stopped the video and thought about it for 10mins or so. And came to the same conclusion. The main thing is with this idea is that it does not break fundamental laws of physics even though it still seems muddle the brain a bit. And yes I also did think about the effect of tacking against the wind. Thanks for this. I have seen some A level example questions of just a wind mill model idea. Now I can introduce this to my students.

    • >> Well I am happy And that makes me happy!