Dope Tech Episode 2

<<@veritasium says : 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).>> <<@RiyaMaurya2013 says : 8:24 whats the song playing in the backround here?>> <<@johnkim1043 says : Although Xyla’s scale model worked on the treadmill (with no tailwind), I still found Mr Cavallaro’s explanation easier to conceptualize than Derek’s.>> <<@billhill897 says : Found another criticism. The flag reversing direction and blowing to the rear suggests the vehicle is moving faster than the wind. This suggests the air is now flowing past the vehicle from front to rear. If that was indeed the case the propeller would reverse its direction of rotation. Not to mention as soon as you reached wind speed the propeller would stop turning and you would lose your source of power.>> <<@waynethomas3638 says : the wind is blowing the 3 wheeler at 10km/h. the wheels are turning at 10 km/h which drives the propeller at 10 km/h which blows air at 10 km/h in rearward direction where upon the forward wind is blowing against the rearward wind wich adds up to 20 km/h vehicle speed>> <<@kwstas2048 says : 9:22>> <<@bobjordan8283 says : When reality and Theory disagree time to think of a new theory!>> <<@angelarredondo611 says : Ok the cylinder earth with two sail boats finally made it clic>> <<@MisterQuacker says : 💜>> <<@nickmitrou6238 says : [sailboat -> cylinder earth -> n sailboats -> prop] was god tier>> <<@selimk.4978 says : What about the gear mechanism behind the propeller? That’s the key point to understand>> <<@MadsterV says : I'm 4 years late but: The sailboat example you showed is excellent, because it's the same reason for both: - going at an angle to the wind means going at the same speed as the wind means accelerating the boat to the vectorial component of the boat's velocity matches the full wind speed... so the boat's total speed is much higher than the wind speed. However there's more resistance, so acceleration is slower (hint hint). - Once the boat has a speed bigger than the wind, you turn around and use that momentum to carry you faster than the wind in the same direction, BUT..... - you MUST again sail at an angle to maintain the speed, otherwise the wind resistance will slow you back down to the wind speed, which is why you NEED to zigzag to pull it off. So after matching wind speed, you're riding on momentum. Now, in that vehicle setup, do you see any flywheels? yes :D a giant one, on top. - As the vehicle gains speed, part of the energy the wind is passing to the vehicle is stored as angular momentum in the fan (without the gearing it would start faster) - When the vehicle reaches wind speed, the fan is now pushing air backwards, so there's a force pushing the vehicle - When the speed of the vehicle is larger than the wind speed, the fan is spending energy, deaccelerating, while the wind is offering resistance to the vehicle and fan, so there's nothing to keep the fan going. - If this slows the vehicle down enough below wind speed, it should be able to accelerate again. So, the speed should oscillate like a pendulum. Balance should be somewhere below wind speed, because of the air being pushed back (discounting all other mechanical force transfer inefficiencies). Think of it as if instead of a fan, it was a wind-charged battery. Does it go faster than the wind? yes while discharging, no while charging. HOWEVER. If you hold it back, it won't oscillate because it won't be using the stored energy, instead it would keep storing more and more, so this is where the illusion comes from in the small scale tests with the treadmill. In the large scale test, it would have to go longer, because it's a rather large pendulum. Once the wind is no longer pushing the vehicle, the fan HAS to slow back down. This is how I see it :) The question is: is the total distance vs time including speed oscillation better than a straight line? because there are curved slopes that get you to destination faster than a straight slope. Same with the boat. It could be marginally better.>> <<@kcpatnaik says : But if the propeller is a fan, wouldn't it create a suction on the telltale and pull it backwards. It may not be an accurate indicator of windspeed vs vehicle speed.>> <<@sriharitkumar3708 says : man someone actually ought to do a cfd simulation on this car>> <<@cadeallen3469 says : Does this mean that if you push the cart on a no wind day it will move forever?>> <<@naoufaltakroumt6373 says : In other words, even magic is scientifically possible>> <<@clementm5417 says : There's indeed nothing weird going on when you pass windspeed because the blade is doing the pushing. But there is a point where something weird happens... because at startup, your wheels aren't turning, so they can't be supplying power to the craft... hence it is being pushed by the wind... then at higher speeds, it's getting power from the wheels. There is a change in modes of propulsion, and because there's no physical reconfiguration of the craft, everything being continuous, there most certainly is a point where the two (or more) modes cancel out. This is most likely why you are waiting for a gust of wind to go over the 8mph or so "barrier">> <<@orangutaneclipse says : This is monumental.>> <<@Miguel.Gallego says : The important detail to understand is that any of propeller’s blades is not moving in the wind direction but in diagonal to the wind direction, like a boat. The reason the propeller isn’t move as a windmill is because the wheels resistance and the pitch of the blades. The wheels play the roll of the keel in a boat.>> <<@johnwynne5657 says : “Tacking downwind” 😂>> <<@Liberty4Ever says : The inventor and owner understand how Blackbird travels downwind faster than the wind speed, but they were stumped about which way to pitch the prop to brake. Apparently, that's more complicated.>> <<@Selendryle says : its kind of like pulleys eh? most of the 'weight' is pushed forward by the wind and the rest is from the wheels to the prop pushing more>> <<@tanavposwal says : Answer at: 18:32>> <<@Evel_CanEvolve says : According to the laws of "intuitive physics," I feel the prop base/wheel base angle should be wider, equal to the angle of the pyramids! 😊>> <<@elroyjennings7833 says : This thing looks about the quality I would build. 3:59 I swear they cut apart a basketball hoop, a bicycle and a canoe for the parts. Oh the steering handle has a sharp edge jabbed into your ribcage so you can get impaled in a crash? Ok let me use my screwdriver to fix it. The steering wheel and the steering axle, are the same part. Just steer using this steel rod that will be up your ass when you crash. Oh a floor? That would add too much weight The driver is too short? Let me move the seat up...I got some pillows in my truck you can put behind the seat.>> <<@simonAverbach says : so doesn't this mean if you just push it slightly it will keep going?>> <<@FJDH11 says : He literally just created a wind version of a warp drive 🤣>> <<@Youtubedotcomma says : Your model at the end, the APC propeller was on backwards… if the propeller when rotating is to generate a pushing thrust backwards then you need to flip the propeller>> <<@mattivirta says : quite cowards, let it burn as fast as it can, it breaks down if it breaks down it doesn't matter>> <<@mattivirta says : who has build this windcar, totally worst build, not strong and good. frame has welding worst than amateur idiot has made this.>> <<@yungsoohong28 says : A square and B square equal to C square. When the cross product if two direction vector is result is larger than input vector, that will be the multiplier factor for acceleration,>> <<@shidanslair says : It seems kinda obvious, the wind pushes the car up to wins speed or almost, then since the wind pushes the car the wheels are rolling and the wheels rolling make the propeler move, then the propeler is adding up the extra speed. It seems like generating energy with a static bicycle, but isn't of a person, the wind is doing the work.>> <<@MonteD1 says : I almost understand, which is good enough.>> <<@dieg45 says : 6:46 😮>> <<@jayaneyon9316 says : I really hate that the prop is on backwards on the example model>> <<@mankisito says : The air wall of the wind and the air wall going backwards created by the propeller hit each other in opposite direction and thus add up to make the vehicle go faster than the wind.>> <<@Pisselton says : 19:35 This hurts my brain so bad. If that's the case, wouldn't the speed of the cart oscillate? I'm gunna have to watch this 100 more times to get it 😂 or just build one>> <<@baronedgar8549 says : The physicists are not wrong but, they did not take into consideration the PROPELLER. The sailboat is not a fair comparison. The propeller needs initial wind to get it to the point that it generates its own energy until it runs out. With a sail when the wind drops the motion stops, the propeller keeps going. Second is the surface you are on. The water would stop the boat dead, a solid surface creates minimal resistance. So the law governing motion is not wrong but it doesn’t take the Propeller and the surface into account.>> <<@LakenesLife says : Where is the video of the gal making 3d printed versions of this?>> <<@techsana3883 says : Please be civil. 🔥>> <<@pierogillio says : If the wind is blowing from behind the propeller shouldn’t spin the other way??>> <<@hardlyfast says : Electronic amplifiers do the same thing: Make a small signal into a large signal by leveraging electrons through negative bias ie using a small amount of bias to amplify current flow. Tubes, transistors all use this concept.>> <<@yves2075 says : Replace air with light, and do that again (faster than light). Seriously. Ever heard of light sails?>> <<@thatonemoviebob says : the explanation in this video isnt good in my opinion, ill explain it with this: imagine a car moving 10 kph downwind with 10 kph winds, the speed in the air is zero, but the speed along the ground is 10, so if you link the propeller to the wheels and make the propeller push you, you of course will start moving forwards faster>> <<@pixelapse9613 says : Why not just control the vehicle using Remote control?>> <<@vasilis746 says : Here I think you are making a mistake, you were confused there. We cannot compare the pure wind speed which is the main source of energy of the vehicle with the kinetic energy of the vehicle which you convert by chains and gears. It is like saying that to lift a rock I will need a greater force than the weight of the rock. However, if I use a lever, a small force is enough. The same happens here with the propeller and the gears. It does not mean that we found energy from nowhere but we exploited the energy of the air that exists while we only measured the speed of the wind, that is the mistake.>> <<@ahmadali-xm9cl says : Good in flat desert>> <<@OLD-GUY-99 says : 9:30. This video is a great representation of how our society has been dumbed down by intellectuals. The professor thought he was using the fork to enhance the speed. As if desire is some form of magic. Most any farmer or backyard mechanic can tell you that this is not occurring. The ability to combine critical observation with common sense seems to have been lost within the intellectual community and universities.>> <<@DjJerryofficialChannel1 says : This is not possible , like a scam. When the wind starts to blow, the windmill will actually spin with the wind, therefore actually making the test car drive backwards. not forwards>> <<@TheOverThinker-e4o says : "we use the whole wind. That saves 65% more wind per wind">>