No, no ,no Xyla.....the propeller on the front of an airplane is there to keep the pilot cool. As has been proven many times over as soon as the propeller stops the pilot starts sweating profusely . LOLOLOLOL
Thank you for not just keeping at it, but also for sharing your struggles. That I love sharing these videos with my engineer minded kids because the are seeing the hard part of the process not just the cool success. Thank you Xyla!!
Xyla has been a big inspiration for helping me get back into creating and making. Ever since leaving faire, I'd been struggling to find something to fill that creative itch, and maker channels like Xyla's have been a big part of discovering it.
@@xylafoxlin a lot of engineering is the iterative process. Never trust version 1 of any process or always expect version 1 to not work as expected. I am currently involved in one project and we are at revision 22
@@xylafoxlin since the propeller acts as a fan once up to that 12mph mark couldn't u make this stationary and instead of driving wheels have it geared to a regular wind powered generator behind it multiplying its speed in low wind areas. Wouldn't once up to speed the front "sail propeller" should start to increase force as the rear generator fan removes back pressure from it creating a tunneling effect increasing the speed, power output and hopefully even reducing the stress of the fans under higher speeds because of the tunneling air with lower speed around it instead of the normal ones in high wind areas with high speeds all around them.
She only said "Yoooooo" because she engineered a fine device, and demos it working on that little treadmill. But it is not doing what they claim it does. That is, they claim that after she releases it, it is being powered by the belt. After she releases it, the prop immediately begins to slow, and in a short while will come to a stop. After it is released, no energy is coming into the vehicle.. But you might ask, "if no energy is coming in, and it is slowing down, how does it surge ahead like it does? Ah yes, good question, and a very simple answer! But, students, i leave that answer up to you
@@37rainman The answer to your question is that for a few seconds after she releases it, the prop has enough thrust to skid the wheels of this very light car over the belt, even tho the wheels are slowing. A longer belt will show that to be true. And the car will be off the back end of the belt within seconds She always ends up grabbing it because it overruns the front end of the treadmill. Get a longer belt
In all seriousness, I watched Derek's video about 3 times and eventually gave up because the sailboat explanation simply just didn't click for me. about half way through your video it all made sense. I know full well that Derek's video helped set the stage for my understanding this problem, but you were able to really drive it home for me.
Try it again this time. The sail explanation is the very core of it that's still pertinent to wind. Derek's demo with the 5 wheel cart pushed along with the wooden bar settles the mechanics of it in more general terms.
@@acctsys Yeah, I got the 'sailboats circumnavigating the cylindrical earth' but had to kinda take it on trust that sailboats *can* beat the wind when tacking. But the five-wheeled cart was such a great demonstration that it was immediately obvious to me. Also made it immediately obvious to me that a version with a squirrel-cage type fan where the largest wheel is would work (given a sufficiently efficient fan).
@@ChrisHow You don't have to "trust" that sailboat can beat the wind, that's the first thing they teach you, don't go straight downwind, it's too slow.
Physicist here, even after watching 2 of Derek's videos I wasn't clear how this works. The final demo in his last video with the rollers convinced me it is real, but your explanation in your "teacher mode" @ 8:00 is what made it finally click! It's really about gear ratios, just that on one end you have propellers and air. :)
The second Derekd's video on the part of the wheels and wood push click me how the theory works, but here on Xyla Teacher mode, i can see how it works on real life. I have a 3D printer and worked on manufacturing before, i will try to build one, BUT, here in Brazil those peaces are not easily and cheap to obtain, i probably will need to print the gears and the propeller as well, i dont think gears is going to be a problem, but the propeller im not sure, never build one before, i dont even know how to start drawing one.
As a millwright I realized immediately that gear ratios are the important fact. Same as a motor turning at 1720 rpm can be either geared up to drive something faster or slower that the actual motor speed. Nice work.
The way Xyla describes it at the beginning is the best way I have yet heard this concept simplified, and the breakdown a little after 7:00 is absolutely excellent.
This is why I play Xyla Foxlin videos for my 2-year old daughter! The smile, laughing, and joy all while building, creating, and innovating! It’s infectious!! Congratulations on proving that prof wrong and helping V win the bet!
You are just an amazing woman and a wonderful communicator of STEM facts. I had seen Derek's video on this but just came upon yours and thoroughly enjoyed it. As a Ph.D. scientist and a father of two women one of whom is an engineer and another a doctor, very heartwarming to see such talented women out there sharing their skills and knowledge for the entire world to appreciate
derek riding in a deadly faster than the wind propcar: *goes faster than the wind, all smiles, no problems* derek holding a faster than the wind model car on a treadmill: *instant damage, blood drawn, his smile and optimism: gone* 🤔
@Antero Kaarakka Well, technically, there wasn't any wind above the treadmill so we could say that the speed of the wind was equal to zero. That being said, since the "toy" was indeed moving forward (thus having a speed superior to zero), we can legitimately say that all of this has something to do with going faster than the wind.
So, I need to do 2 things: Flip the prop over on the drive shaft (so the writing "14x4.7" on the prop is facing forwards in the direction the wind car is intended to go), and make sure it is attached well and not slipping. Propellers are not actually symmetrical when flipped over on the drive shaft, so the correct way works more efficiently to grab the air.
I think her pride made her omit/hide that mistake. I say this because even after she discovered her mistake, which is probably the cause of her 2 first failures, she doesn't even mention the prop direction in her build tutorial. That or she didn't actually notice her mistake and its by pure luck that she put it the right way for her last try. Anyway, it looks bad coming from someone who loves to brag about being an 'engineer'. I have yet to see her actually do some engineering rather than just some crafting.
In the first test the prop was spinning in the wrong direction as well as being on backwards , looking at the rear it was turning counterclockwise, which would make the air blow towards the front and pushing the vehicle rearward.(2:55) , I slowed the video down to verify.
@@JH-fk8ow Of course but then you could say how much does he get paid for the views he got on youtube for the 2 videos? I'm sure he enjoyed doing it as well.
"I actually managed to get away with freezing the axle, heating the bearing and just going for it." I really like how simple but genius you made it seem! Kudos
@@ionbusman2086 The bearing races are hardened but the shields are real soft and could easily get bent into either cage or race. There is also a problem known as 'Brinnelling' (from Brinnel the 19th C engineer) where the ball bearings cause 'dimples' in the races and flats on the ball.
I just watched this again. I found your channel because of Derek, Veritasium and this video. You have done so many amazing things and it makes me sincerely happy to see you still going, through all of the trials and tribulations life has thrown at you over the last few years.
I love Emily's comment, "It's beautiful!". I completely agree with her. It's beautiful to see it working and also the process you went through to get it to work.
Have you seen this Veritasium video "This equation will change how you see the world" I nearly cried when it turned into the Mandlebrot set - it was so astonishingly beautiful the perfection of it...
Finished my build at last night. I made the front axle 12 inches like the video says. The rear axle size was not given, but 5 inches worked well for me. I did NOT need to sand the axles or drive shaft, just put them into the freezer for 10 minutes, and then heat the bearing for 60 seconds in microwave wrapped in 3 very wet paper towels on a dish. Then press the bearing on the shaft, with gentle hammering. Adjustments of bearings on shafts were made with the help of a small vice. Glue-ing with superglue or gorilla glue was a little tricky. The gears are small, and you do not want any on the rotating parts of bearings, etc. Tried to make sure everything was aligned well so less friction, and added some oil to the bearings helped too. Still waiting to find a treadmill to use for testing. Unsurprisingly, it looks just like the one Xyla made. Sadly this prototype is very flimsy. It is probably strong enough to prove the point on a short treadmill test, but I doubt it will hold up to more than that. Probably cannot run it on a street for instance.
Do a real test. Put it on a much longer belt of the same speed. You will very quickly see that it actually doesnt work. The test on the treadmill actually wasnt a test at all
@@ronalddump4061 Please add the link to your video supporting your claims. That would be a video showing your build following her plans, a test on a short treadmill where your model works and then a test on long treadmill where the same model fails. I am really looking forward to the link.
@@tomm.149 Just to be clear. That is not how science works. They made the statement, they made the vid which supposedly supports the statement. But the vid shows no real test of the device. "Amazing claims require amazing proof" ron is entirely within his rights to simply say, no it doesnt work. They need to prove it does work. Functional people prove positives, not negatives. Ron outlined a simple real test, now it is up to them to prove it does work. There would be no end to constantly be trying to prove peoples ignorant assertions are false, because stupidity is infinite, for proof, just look at these utube comments
Actually Veritasium is a much better known channel, having almost ten million subscribers. Xyla was recommended to me just a few weeks ago, and now I find they have a collab, that's really awesome. I hope some day Xyla will have millions of subscribers as well, she really deserves it.
This massive collaboration really shows us the best side of youtube. This is desperately needed in those strange and maybe dark times we seem to be living in with so many global problems that we just don't seem to be able to solve and all those people, who are using the platform to spread harmfull information.
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Times have never been as good. Most things are getting better all the time. You just don't hear about it on the news.
@ My comment isn't about what is, but about what's to come, especially if we don't address global warming, overpopulation, our ecological footprints and biodiversity loss. One really has to be asleep to not understand the challanges and dangers associated with those problems. And we're nowhere near solving those problems. Quite the opposite we're currently showing that our system doesn't seem capable of dealing with those problems adequately.
The first 2 attempts you had the prop on backwards! The last design you had it on correct. As an RC pilot, this is something that catches my eye all the time!
@@ntsure2436 Exactly. Props (except for reversible pitch props used for very specific aerobatic model aircraft) have camber. Running them backwards makes a lot of noise and a little bit of thrust, but nowhere near as much as when they are going the right way. The concave side should always be facing backwards (so for a 'pusher' design, you have to mount it backwards with respect to the shaft).
I was looking for that comment :D Buggered me as well. Otherwise an awesome build, so nice that it's open source and essentially anybody around the globe can build it. Well done!
This whole thing has become like a physics rap battle lol, you guys even pulled Neil Degrasse Tyson and Bill Nye into it 😂. Good work helping to settle a decades old debate!
It was settled decades ago. Professor Drela made it clear that the equations have been used for a long time to eliminate the exact issues that UCLA had in his truncated calculations.
On an unrelated note, I'm glad to see the cow jokes transcend language barriers. In Poland we often assume cows are perfect cylinders for moment of inertia calculations in high school. That "spherical cow" was the first time I heard about it in English. It doesn't quite refer to the same thing, it's more of a principle, but there's also a cow! :d
@@Nabuchodonozord "Consider a cylindrical cow." ?? Why would anyone want the moment of inertia of a cow? Even if you are interested in the variable power requirements for rotating milking stalls you surely can treat the cows as point masses. Or can you? Damn... I'm sure I did when I constructed an exam question about milking stalls but now you've made me think I might have over simplified.
9:48 - If you want to reduce the friction even more, pry out the shield in those ZZ rated bearings, wash out the grease and add sewing machine oil. That or get some fidget spinners and steal the bearings out of those.
"you can go downwind faster than the wind" People: :0 Me, a sailor: ok yes (Yes I know that this is different because it's _directly_ downwind and not at an angle, but from what I understood of veritasium's video, it's really the same concept because it's the prop blades that are angled)
This is how I understood it... What's the problem? A ship can go faster than the wind? The answer is YES !! The propeller has high torque but LOW velocity and the wheel has low torque but HIGH velocity... So there's no extra energy, the Veritasium ship can do it !!
@@kwinterburn But you can’t exceed the tailwind. In fact, minus friction, you can’t even keep up. The closest to this is traveling by air balloon; you’re traveling at almost. Wind speed, so you don’t feel a breeze.
@@37rainman it would and it would accelerate forever. There is a little problem that nobody seems to pick up though....it is not the relative wind moving it, it is the motor of the threadmill that supplies that energy that allows the model to accelerate. A better experiment would be to put the model in a wind tunnel and see if it would accelerate. It wouldnt.
I'm a reasonably sciencey guy but.... I can't wrap my head around the physics of this (and I saw the original full-scale build). Thank you for being a fun inspiration you people who are interested in science. A 20-minute video like this is worth more than a semester of boring HS science classes.
Congratulations on the successful build! You're right at the top of the makers I've found this year. I hope the colab with Veritasium brings you many new subscribers and gives you momentum to make more amazing things.
Well done! Oh, and yeah, we (model airplane pilots) always scrape, or sand, that mold line at the edge of a nylon/glass prop before putting them on the plane, especially those grey APC props. I've seen guys put one on out of the bag, hand flip it to start the engine and lay their fingers wide open on that sharp edge.
Magnificent. I shared your stuff, especially this one, with my grandson who is finishing high school and had decided he wants to be a maths and science teacher here in Australia. Shhhhh..... I couldn't be more proud. (Yes, he knows how excited and proud I am about it.)
Awesome, and great to show the iterative journey of engineering! One little detail to maybe add: I noticed in Derek's first video, when he used the cart as an explainer prop, that the propeller was mounted "backwards". Most propellers are asymmetric, and have preferred direction. The more rounded part of the blade should face forward, the more hollowed side backwards. As a model airplane builder, it instantly stood out to me, but isn't super obvious otherwise I guess. It seems, watching these two new videos now, that this might have been a confounding factor in some of your earlier versions, additionally to the prop size and pitch - "backwards" the prop efficiency is much, much worse, very ineffective. I was about to comment on it on Derek's initial video, but I didn't, as I thought it doesn't matter, and nobody will read it anyway... now, after seeing how much was at stake beyond just a video explainer prop model, I feel a bit bad about not commenting on it back then! In any case, on the final cart it was right, so you probably figured it out already. Just thought it might be good to know for people who want to replicate it :)
This caught my eye as well, also came here to comment the same thing 😁 I'll add here another thought for simplicity: A general rule to RC props is that the text on the prop should be facing the forward direction of the model 🙂
@@vanguard6937 The idea behind the backwards prop is to convert the power of the tailwind to a propulsive force on the driven wheels. Similar to the principle behind any perpetual motion machine.
If you're not a pilot, or enthusiast, or mechanical engineer, you might not know that the main axle is going to want to rotate with the tail wheel dragging if the center of gravity is behind the axle. That's why you get that left right sway. It's also an important thing to consider when loading uhauls and trailers. And if you see that guy with trailer swaying like a mofo. Now you know. Want a TH-cam example look up "ground looping".. so it would be more stable with the main axle in the rear and weight in front with small nose wheel.
Does not apply ... dynamic forces are different ... it's not powered above the axle but through the axle and 90 degrees to it ... not a puller prop ... angle of pusher prop is down through the front axle, there is a force through the prop shaft down into the front axle ... there are 4 equal size wheels that do not swivel (tail draggers the rear swivels, it's mass is much lower, the radius is much smaller) ... planes generate lift ... the angle of motion is in the direction of heading. Ground looping is predominately due to the latter, when the heading is different from the direction of travel. Think precession ... the turn causes the torque ... the torque doesn't cause the turn. You have to think of it more as if it were a sailboat with a keel mixed with a helicopter. The advancing port side (Left side) of the prop has more resistance because the prop (clockwise rotation) is at an angle in the direction of motion. The Starboard (Right side) is receding and will have less resistance. Think of why a helicopter has a tail rotor and a sail boat has a rudder. Yeah they are there to steer ... but also to counteract the gyroscopic and inequality of resistance forces.
Regarding trailers ... the force that creates the sway is ahead of the axel at a pivot point and also due to rolling resistance (one tire under inflated, bearings shot, different tread, tire size, etc). An axle forward of the center of gravity unloads the pivot point and creates a greater steering torque around the axle giving more momentum to the mass behind it. The contraption in the video has the pivot point at the axle not ahead of it. Planes in the tractor (pull) orientation are the same, the pivot force is ahead of the axel. The only 4 non pivoting wheel trailers I've seen are on railroad tracks.
I'm perplexed how you would put the main axle with the prop at the rear while having the smaller wheels in the front with most of the mass unless you unnecessarily added it there.
@@ejrupp9555 after misloading my ATV's on my trailer *once* and almost putting my truck into a guard rail when younger. I very quickly learned proper loading :) Also: if the center of mass leaves its base, it'll fall over: the scientific reason I cant ride a skate board..
Xyla, Great Job with making a working model to prove a difficult concept, Thanks for sharing. I have a few comments that may help others with the formula given as not being an engineer I could not follow exactly how you described the formula. Formula given: (Propeller distance / Wheel distance) must be less than .7. What does the propeller distance means? “Propeller distance” means the distance a propeller will travel perpendicular to the propeller rotation in one full rotation. This is determined by the pitch of the propeller. In this case a 4.7 pitch propeller is used so the propeller will move 4.7 inches in the direction the vehicle is moving after one full rotation. (Since the propeller on this vehicle is not perpendicular to the ground this will not be 100% accurate.) “Wheel distance” means the distance a wheel will travel in one full rotation. This is equal to the diameter of the wheel times Pi or approximately 3.14159. So 4.7 inches (distance traveled by the propeller) divided by the wheel diameter X times 3.14159 (or Pi) must be .7 or less. To find the minimum wheel diameter set formula to = .7 To solve for the wheel diameter, (Propeller Distance/ Wheel diameter X 3.14159) =.7 First multiple each side by the wheel diameter or X to get the wheel diameter on the other side of the equation. So .7X = 4.7/3.14159, Next divide each side by .7 to get the wheel diameter by itself. X = 4.7/ 3.14159 time .7 so X = 2.137” minimum wheel diameter. I hope this is accurate otherwise I’m sure others on the site will let me know. Thanks, Greg
Man, I love your enthusiasm on these projects you do. It's infectious. Great content from a great channel. Oh.. and by the way my daughters think you're awesome too :)
I'll be honest. I got more excited over your appearance in Derek's video than I did for Bill Nye AND Neil deGrasse Tyson' cameo. Your work is so awesome!
Yes, it is possible for a wind-powered vehicle to outrun the wind it is traveling with under specific conditions. This concept is counterintuitive but has been demonstrated through a principle known as downwind faster than the wind (DWFTTW). How It Works: 1. Mechanism: The vehicle, like the famous "Blackbird" cart, uses a propeller connected to its wheels via a transmission system. As the wind pushes the vehicle, the wheels drive the propeller, which generates thrust. This thrust propels the vehicle forward faster than the wind. 2. Key Idea: The propeller is not just passively driven by the wind; instead, it acts like a fan, actively pushing air backward. The power to spin the propeller comes from the movement of the vehicle's wheels on the ground. 3. Energy Source: The wind provides the initial energy. Once the vehicle gains momentum, the relative motion of the wheels powers the propeller to push the vehicle forward faster than the wind itself. Demonstration: In 2010, Rick Cavallaro's Blackbird cart demonstrated this phenomenon. It traveled 2.8 times faster than the wind in a controlled environment, confirming the concept. Why It Doesn’t Break Physics: This phenomenon might seem to violate the laws of physics, but it doesn't. The system relies on clever engineering to harness wind energy more efficiently. The key is that the vehicle continuously extracts energy from the wind relative to the ground.
Another significant change you made in the final version was lengthening the vehicle. In the earlier versions your propeller was pointed more downward, so more of the force was directed into the ground rather than to pushing the car forward. Just eyeballing it (based on the geometry of the cars and a bit of trig) I'd guess that the wasted force (maybe 10% on the earlier version) is decreased by 30-40%. Basically you're gaining a few percent thrust with no significant cost. The blackbird, or the earlier vehicles that were built in the 60's - 90's, had a bit more gearing to get the propeller completely horizontal. I understand why you didn't do that, but the smaller angle does make a big difference.
This is so ridiculously cool, Xyla! 🙀 Incredible engineering & stunning aesthetics! One of the things I admire most about your work is that so many of your creations could stand alone equally either for their engineering merit or their artistic value. A lot of people create functional things that also look nice. But with you and your creations, you are truly an incredible artist in every right just as much as you are a phenomenal engineer.
Great video Xyla. I just ran across you on Veritasium's video. Smart, funny, personable and persistent. I loved the way you laughed when the models failed, made modifications until success... and then "exploded" upon that success ~ just a lot of fun to watch. A great example to all the young and upcoming tinkerers out there (which is where a lot science starts)... I think I will have to subscribe.
_"All these people just need to learn not to put their appendages where propellers are."_ -- Xyla Foxlin, 2021 I have worked in aviation for a few decades, and I THOROUGHLY APPROVE this quote...😊 BTW: *TAKE THAT, ACADEMIA!!!!* 😄😄😄😄😄
Well done, as always! And "Pog!" as suggested on Integza's Discord! =) (Disclaimer* I'm a "Xennial" so I often don't get the context of words like "Pog," but I looked it up on Urban Dictionary and it had mostly positive connotations, Integza seems like a pretty cool TH-camr and likely has positive intentions, and I personally intend it in only the most positive way!!) Keep up the good work! =)
Neat! well done I have a thought on these treadmill tests in general.From comments i see on other videos ,it's obvious the treadmill test screws with people's brains! Most would be better off watching the full size Blackbird.It saves one whole extra layer of complication
thought to watch this when I watched Derek's video but actually forgot it as I was excited about the SciComm Contest but finally watched it! What a beautiful Engineering! And obviously Rick is literally a genius.
Incredible!! I just watched Derek’s video and finished watching yours. I follow several engineering TH-cam channels and yours is definitely one of the best. Great job.
I'm sure people tell you all the time they love your energy. So forgive me for saying the same. I used to date a girl who was equally energetic, who used clever puns in her speech, and, believe it or not, who had a strikingly similar voice to you. She was a joy to be around, always lifted the spirits of anyone in her presence, and was incredibly inspirational. I think I created more art during the one year we dated than in the 10 years after. I loved not being the smartest one in the room, though she never intimidated anyone because of her light-hearted and silly demeanor, and I constantly found myself learning something new from her. I supposed what I'm trying to say is all of these wonderful qualities pertain to you as well. I've watched nearly all of your videos and am thoroughly enjoying your channel.
Hey, I am sure someone probably told you this but for the first two versions of the cart, you had the prop flipped backward. RC propellers are only designed to be spun with the numbers for prop's size and pitch on the side facing the same direction as travel (unless the prop was designed for clockwise motors or backward facing counter-clockwise motors). If you have them flipped incorrectly they still generate force it is just far less and is very inefficient.
I think no one yet has understood that it is the Bernoulli principle and not air being thrust it out the back. I was kind of surprised that the contract was signed by physics majors.
Wow, I genuinely appreciate the effort to replicate this and especially to make it reproducible by other people. This is what science is meant to look like.
What this does is specifically test the good professor's belief that the treadmill case will falsify the land-racer case. I find the treadmill case dead simple and altogether transparent, but if we want to translate it to a more side-by-side comparison to the land-case, let's take a rugged 100m strip of 1m wide treadmill rubber to the land-course and pull it behind a car, using a second car holding a wind-screen out sideways ahead of the model. At least as a gedankenexperiment, because this sort of thing is beyond my resources. Perhaps Adam Savage might want to pull it off-so to speak-some day. Will the result match what we see in the video? Yes, all things being equal, it should. Our model is going to keep advancing until it reaches the car, and it's very obvious why. The gear ratio and the constant supply of energy guarantees it. It is not analogous to the wind-car arrangement proper.
@@-danR Some such scenario might be interesting, but that one isn't quite it. The treadmill belt needs to move rapidly rearward with respect to the cart. (Well, I mean, rearward with respect to the air, so then even more rapidly rearward with respect to the cart when the cart starts making its way forward through the air.)
Pro tip for cutting aluminum tube for future use.. use a utility knife and with the blade pushing where you want your cut, roll the tube back and forth.. 4-5 rolls later and your start cutting the tube
it looks really, cool. particularly because it is so mechanically simple! But does the prop rpm actually stay the same or increase as it travells against the treadmill ? :)
Totally awesome. Congrats from a "self taught, backyard, small engine mechanic". I am 65 years old in body only. At S.A.I.T (Canada) 46 years ago we learned about the perpetual motion machine.
I think it's so awesome that you were mechanically failing because you were trying to make it accessible to your audience to build. Libraries are starting to host 3d printers. I hope more come to public access. If you have some local workshop in your town they will probably have one too. Go out and craft!
My high school got a grant for one in 2014-15, when they started to become popular with the general public. Super cool, my district wasn't well off, so it was a big deal.
But she knows not to put her appendages where blades are. I used a drill press in high school and I would absolutely love to have one, but I drill like Xyla does. I always stop and eyeball to make sure that nothing's in the way before I drill through something.
Looking at the wounds, someone forgot to give their kids the "high speed go rounders are always trying to kill you" speech. Is that speech only something farm kids hear? There were a lot of speeches of this nature. Basically, all farm equipment, power equipment, water, electricity, and other forms of active or stored energy can and will attack without warning. Shark Week draws viewers, but Cow Week kills more. Fun video. I wish I had the time to play like this, maybe when I retire.
So now that its proven, there needs to be a yearly competition to see who can make the fastest/lightweight/interesting cart. Just need a really long treadmill!
Well, if this works as it should, all you need is a very long and flat surface and enough tail wind to get the craft up to speed. I could see this being a thing in one of those salt flats.
@@Eagleizer the treadmill is an exact analogue to a tail wind. its like watching the cart from the reference frame of the wind, the ground appears to move. If you disconnected the treadmill, the "wind" would quickly die out.
Would be more fun to have head to head races across a big stadium floor with some fans blowing from one side to the other. I know it can be done. I've seen indoor RC sailing races.
Question: Wouldn't it be better if the prop would be rotating parallel to the floor? That angle does make you loose on thrust - in my guess - of about 20-30%
I think it would too. My hunch of why it was not done as such is to reduce mechanism complexity and avoid the resultant frictional losses. Edit: Upon further reflection, making the propeller tilted downwards had another benefit too. Noticed that she added rubber rings to the wheels? Apparently it had insufficient traction. That rubber provided more traction. This angled propellers introduced downforce which also helped to increase traction. The actual rideable vehicle had propellers parallel to the ground. The vehicle was heavy enough that it had no traction issue. Best to angle them parallel for maximum forward force.
Measuring off the video, the angle is about 16 degrees. Cos 16 is approx 0.96, so the angle of the shaft makes the thrust loss about 4%. I guess a more complex gear and shaft system to get the thrust line horizontal would introduce drag and a similar loss, as well as being more complex to build.
I know what you mean, but you are on the wrong axis. Either the prop is perpendicular to the ground, or the prop shaft is parallel. I also wondered about that, but it would have added mechanical losses that might have exceeded the gains from the on-axis thrust. If I had to guess, using a piece of flexible tubing (like Tygon) as a drive shaft would have been the most accessible low loss flex, but it would have required 2 more bearings and the associated framework because both ends of the two rigid shafts would need to be supported. Another close design in terms of loss would have been a horizontal drive shaft with a pulley under the rear tower, with a belt drive up to a horizontal prop shaft. Again, each shaft would need two bearings and associated framework. The design she made has the fewest parts, and was very forgiving of small misalignments, thus probably has a better chance of being successfully built by inexperienced makers, which is a win for everybody. This is really just 1 step up from a rubber band powered balsa airplane.
Nicely done, thank you for that amazing experiment. One small remark: at 5.43 the propeller is inverted which gives a very bad efficiency contributing to the failure of the experiment. At 13:58, you got the prop in the right position. (I am playing with propellers for 45 years ;-)
5:28 The propeller orientation is wrong I guess. That might be the reason. Propellers consist of airfoils like a simple wing. If you place the propeller in the wrong direction, the thrust will drop to almost half the normal value since the trailing edge of the airfoil is facing with upstream air (in the tangential direction). If you want to use that propeller to push the vehicle, you have to change the direction of rotation in the opposite direction.
Same thing caught my eye, but for most of the video it was really hard to tell. Maybe some visual illusion made it seem wrong. But right after 12:00, you can clearly see the camber is the right way.
So many physicists have described this as impossible. I watched threads go on for 1000's of posts 12 years ago when Rick Cavalarro build BlackBird with physicists claiming it was impossible and a fake. Often folks initial reaction was outrage and that outrage seemed to generate a self-sustaining state that caused part of their mind to turn off and stay stuck off.
@@kholofelolebepe9637 It's more than gearing ratio... The thing is accelerating. But this is an interesting question. You'd have to increase the slope of the treadmill commensurate with the increase in speed of the model. It seems like there ought to be a limit to its speed -- but I'm not sure. You could tie a string to the back of it fixed to a stationary point; and then slowly increase the slope of the treadmill till it couldn't keep up with the incline.
@@KevinMcMahon-hy2kl Have ever ridden a bike with multiple gears or driven a manual car?.Then you will know that you will have to change the gearing in order to go uphill so you don`t stall. Blackbird is basically like a simple lever, and like a simple lever, you get more output force(Thrust) than the initial input force(wind speed),depending on the distance between the fulcrum and initia input force which is the torque, in this case the fulcrum and distance being the gearing ratio. The torque of the system still remains the same
@@kholofelolebepe9637 But it's not gaining its forward velocity through the wheels; it's actually transferring the energy of its moving wheels into forward thrust via the propeller. It's kind of like the classic MythBusters "Will a plane take off on a treadmill?" episode. Wheel torque doesn't have much to do with it. At a certain point though, the vehicle will be fighting its own weight vs. gravity on an incline.
That car will never stop if the wind always blowing. Keep your awesome idea up like this perfect car. -Pog And now ur mission is click the like button Also Tomatoes is disgusting
No, no ,no Xyla.....the propeller on the front of an airplane is there to keep the pilot cool. As has been proven many times over as soon as the propeller stops the pilot starts sweating profusely . LOLOLOLOL
Can confirm!
This was too great. Thanks for making me laugh so hard today. Cheers!
@@231pilot LOL
@@sanyi1975 It really does. The cabin air scoops are right behind the propeller, works great on the ground!
Also a Piper Cub is a very safe airplane......it flies barely fast enough to kill you. LOLOL
That was AWESOME!!! Loved everything about this video. Keep it up!!!
I have a message for James,
Hope your hand heals.
From, the Fans
Hi
Make a large scale version !
Please can you build us à" turbo voile "?
You ll be surprise 👍👍👍👍👍👍👍
fr.m.wikipedia.org/wiki/Turbovoile
Make it real
Thank you for not just keeping at it, but also for sharing your struggles. That I love sharing these videos with my engineer minded kids because the are seeing the hard part of the process not just the cool success. Thank you Xyla!!
Thanks so much! It's hard on the ego to leave them in but I think it's important. No one succeeds the first try!
@@xylafoxlin "Success is falling down nine times, and getting up ten" ~ Jon Bon Jovi
Xyla has been a big inspiration for helping me get back into creating and making. Ever since leaving faire, I'd been struggling to find something to fill that creative itch, and maker channels like Xyla's have been a big part of discovering it.
@@xylafoxlin a lot of engineering is the iterative process. Never trust version 1 of any process or always expect version 1 to not work as expected. I am currently involved in one project and we are at revision 22
@@xylafoxlin since the propeller acts as a fan once up to that 12mph mark couldn't u make this stationary and instead of driving wheels have it geared to a regular wind powered generator behind it multiplying its speed in low wind areas. Wouldn't once up to speed the front "sail propeller" should start to increase force as the rear generator fan removes back pressure from it creating a tunneling effect increasing the speed, power output and hopefully even reducing the stress of the fans under higher speeds because of the tunneling air with lower speed around it instead of the normal ones in high wind areas with high speeds all around them.
This was SO impressive! You know that you're doing something right, when an astrophysicist is wowed by your accomplishment in physics.
"Eureka!" - Archimedes
"Yoooooo!" - Xyla Foxlin...and everyone else from now on.
Iconic
That sound bite will live on for generations.
insert japanese bruh sound
She only said "Yoooooo" because she engineered a fine device, and demos it working on that little treadmill.
But it is not doing what they claim it does. That is, they claim that after she releases it, it is being powered by the belt.
After she releases it, the prop immediately begins to slow, and in a short while will come to a stop. After it is released, no energy is coming into the vehicle..
But you might ask, "if no energy is coming in, and it is slowing down, how does it surge ahead like it does?
Ah yes, good question, and a very simple answer! But, students, i leave that answer up to you
@@37rainman The answer to your question is that for a few seconds after she releases it, the prop has enough thrust to skid the wheels of this very light car over the belt, even tho the wheels are slowing.
A longer belt will show that to be true. And the car will be off the back end of the belt within seconds
She always ends up grabbing it because it overruns the front end of the treadmill. Get a longer belt
In all seriousness, I watched Derek's video about 3 times and eventually gave up because the sailboat explanation simply just didn't click for me. about half way through your video it all made sense. I know full well that Derek's video helped set the stage for my understanding this problem, but you were able to really drive it home for me.
Wow, big compliment! Thank you!
Try it again this time. The sail explanation is the very core of it that's still pertinent to wind. Derek's demo with the 5 wheel cart pushed along with the wooden bar settles the mechanics of it in more general terms.
@@acctsys This. People blaming Derek for not changing reality. :facepalm:
@@acctsys Yeah, I got the 'sailboats circumnavigating the cylindrical earth' but had to kinda take it on trust that sailboats *can* beat the wind when tacking. But the five-wheeled cart was such a great demonstration that it was immediately obvious to me. Also made it immediately obvious to me that a version with a squirrel-cage type fan where the largest wheel is would work (given a sufficiently efficient fan).
@@ChrisHow You don't have to "trust" that sailboat can beat the wind, that's the first thing they teach you, don't go straight downwind, it's too slow.
Physicist here, even after watching 2 of Derek's videos I wasn't clear how this works. The final demo in his last video with the rollers convinced me it is real, but your explanation in your "teacher mode" @ 8:00 is what made it finally click! It's really about gear ratios, just that on one end you have propellers and air. :)
It's the glasses isn't it
@@xylafoxlin nah, the voice
@@xylafoxlin
the glasses made me snort
The second Derekd's video on the part of the wheels and wood push click me how the theory works, but here on Xyla Teacher mode, i can see how it works on real life.
I have a 3D printer and worked on manufacturing before, i will try to build one, BUT, here in Brazil those peaces are not easily and cheap to obtain, i probably will need to print the gears and the propeller as well, i dont think gears is going to be a problem, but the propeller im not sure, never build one before, i dont even know how to start drawing one.
As a millwright I realized immediately that gear ratios are the important fact. Same as a motor turning at 1720 rpm can be either geared up to drive something faster or slower that the actual motor speed. Nice work.
The way Xyla describes it at the beginning is the best way I have yet heard this concept simplified, and the breakdown a little after 7:00 is absolutely excellent.
I guess I'm not the only one who forgets safety glasses
not only glasses just you forgot “safety” ;)
We are video AND negligence buddies now!!!
you did better than her
Sup bois. Looks like this car started quite a stir
POG
This is why I play Xyla Foxlin videos for my 2-year old daughter! The smile, laughing, and joy all while building, creating, and innovating! It’s infectious!!
Congratulations on proving that prof wrong and helping V win the bet!
This means that Derek was injured more on the model than on the life-sized run. :)
I think everyone would rather be hit by the model prop. Can you imagine if that happened while he was driving the full-sized one?
@@nommy8599 his head wouldve fallen off if he get hit with the big one
Yeah, i watch the video. That thing looks sketchy as fk 😂
You are just an amazing woman and a wonderful communicator of STEM facts. I had seen Derek's video on this but just came upon yours and thoroughly enjoyed it. As a Ph.D. scientist and a father of two women one of whom is an engineer and another a doctor, very heartwarming to see such talented women out there sharing their skills and knowledge for the entire world to appreciate
Iterative design and 3D printing are great but relentless engineering is unbeatable, great job!!
Hi
Yes Ivan. But when are you going to print your own life size propeller wind kart?
@@foamboard_shenanigans with plenty of spacers!
They should mass produce this as toys for profit!
@Gus Erland wtf is wrong with you
derek riding in a deadly faster than the wind propcar: *goes faster than the wind, all smiles, no problems*
derek holding a faster than the wind model car on a treadmill: *instant damage, blood drawn, his smile and optimism: gone*
🤔
Humans are weird. Can confirm from personal experience. :D
It turns out that Xyla is an airplane pilot. She understands about keeping away from propellers. Derek obviously isn't and doesn't.
@Antero Kaarakka Well, technically, there wasn't any wind above the treadmill so we could say that the speed of the wind was equal to zero. That being said, since the "toy" was indeed moving forward (thus having a speed superior to zero), we can legitimately say that all of this has something to do with going faster than the wind.
Derek: "You forgot your safety glasses". Xyla: "You forgot the giant spinning blade near your hand".
So, I need to do 2 things:
Flip the prop over on the drive shaft (so the writing "14x4.7" on the prop is facing forwards in the direction the wind car is intended to go),
and make sure it is attached well and not slipping.
Propellers are not actually symmetrical when flipped over on the drive shaft, so the correct way works more efficiently to grab the air.
I think her pride made her omit/hide that mistake. I say this because even after she discovered her mistake, which is probably the cause of her 2 first failures, she doesn't even mention the prop direction in her build tutorial. That or she didn't actually notice her mistake and its by pure luck that she put it the right way for her last try. Anyway, it looks bad coming from someone who loves to brag about being an 'engineer'. I have yet to see her actually do some engineering rather than just some crafting.
In the first test the prop was spinning in the wrong direction as well as being on backwards , looking at the rear it was turning counterclockwise, which would make the air blow towards the front and pushing the vehicle rearward.(2:55) , I slowed the video down to verify.
amazing! it's so great to see you not giving up and overcoming all difficulties eventually. this is how things get done
thats not impossible just you must know bit of physic.
$10k is a pretty good incentive.
> this is how things get done
💯 "Fall down seven times, stand up eight"
@@matthewtalbot-paine7977 pocket change for a guy with tens of millions... and he was giving it away from the get go, it wasnt about money.
@@JH-fk8ow Of course but then you could say how much does he get paid for the views he got on youtube for the 2 videos? I'm sure he enjoyed doing it as well.
Every time Derek was holding itI was like duuuuuuuudee don't hold it like that!
I love how you made the gear ratio 1:1 to remove the variable. Just like the math equation you simplified to only need to tweak the propeller pitch.
I sometimes come back to this video when I feel discouraged. Your determination is inspiring to me.
This is beyond cool! Glad to see you got it working in the end 😊
"I actually managed to get away with freezing the axle, heating the bearing and just going for it." I really like how simple but genius you made it seem! Kudos
That's been the standard way of doing it since forever.
@@Lappmogel Yeah, maintenance techs and machinists do this every day.
@@st3vorocks290 Yep, got the stink eye from the ex several times for having car parts in the oven and/or freezer 😂
lol yeah, the frost in my freezer has little backwards "timken" logos everywhere 😃
They teach that method in every meche class ever lol
“These bearings are critical” she says as she smacks them into place with a pair of pliers…. Too funny!
Not like that would damage them tho
Hammers and brute force are engineers best friend
@@ionbusman2086 That might damage them if you force on the wrong ring
@@ionbusman2086 The bearing races are hardened but the shields are real soft and could easily get bent into either cage or race. There is also a problem known as 'Brinnelling' (from Brinnel the 19th C engineer) where the ball bearings cause 'dimples' in the races and flats on the ball.
One doesn't even need to be an engineer, its enough to be a skater and understand how bearings break
I just watched this again. I found your channel because of Derek, Veritasium and this video. You have done so many amazing things and it makes me sincerely happy to see you still going, through all of the trials and tribulations life has thrown at you over the last few years.
Xyla is absolutely amazing and never fails to impress me.
I love Emily's comment, "It's beautiful!". I completely agree with her. It's beautiful to see it working and also the process you went through to get it to work.
Have you seen this Veritasium video "This equation will change how you see the world" I nearly cried when it turned into the Mandlebrot set - it was so astonishingly beautiful the perfection of it...
Finished my build at last night. I made the front axle 12 inches like the video says. The rear axle size was not given, but 5 inches worked well for me. I did NOT need to sand the axles or drive shaft, just put them into the freezer for 10 minutes, and then heat the bearing for 60 seconds in microwave wrapped in 3 very wet paper towels on a dish. Then press the bearing on the shaft, with gentle hammering. Adjustments of bearings on shafts were made with the help of a small vice. Glue-ing with superglue or gorilla glue was a little tricky. The gears are small, and you do not want any on the rotating parts of bearings, etc. Tried to make sure everything was aligned well so less friction, and added some oil to the bearings helped too. Still waiting to find a treadmill to use for testing. Unsurprisingly, it looks just like the one Xyla made. Sadly this prototype is very flimsy. It is probably strong enough to prove the point on a short treadmill test, but I doubt it will hold up to more than that. Probably cannot run it on a street for instance.
Do a real test. Put it on a much longer belt of the same speed. You will very quickly see that it actually doesnt work. The test on the treadmill actually wasnt a test at all
@@ronalddump4061 Please add the link to your video supporting your claims. That would be a video showing your build following her plans, a test on a short treadmill where your model works and then a test on long treadmill where the same model fails. I am really looking forward to the link.
@@tomm.149 Just to be clear. That is not how science works. They made the statement, they made the vid which supposedly supports the statement. But the vid shows no real test of the device.
"Amazing claims require amazing proof"
ron is entirely within his rights to simply say, no it doesnt work. They need to prove it does work. Functional people prove positives, not negatives. Ron outlined a simple real test, now it is up to them to prove it does work.
There would be no end to constantly be trying to prove peoples ignorant assertions are false, because stupidity is infinite, for proof, just look at these utube comments
@@ronalddump4061 OK here’s one one a much longer belt… actually infinite in length. th-cam.com/video/VkPW9ql6t_A/w-d-xo.html
@@archimedesmaid3602 Giving link again since I’m curious what you’ve have to say about it too th-cam.com/video/VkPW9ql6t_A/w-d-xo.html
This pleases me as much as your lighted glass kayak!! Isn't, "It can't be done!" the best motivator.
Thanks Xyla for introducing me to this Veritasium guy!
Always fun when the great youtubers shows the lesser known ones 🤓
Actually Veritasium is a much better known channel, having almost ten million subscribers. Xyla was recommended to me just a few weeks ago, and now I find they have a collab, that's really awesome. I hope some day Xyla will have millions of subscribers as well, she really deserves it.
This massive collaboration really shows us the best side of youtube. This is desperately needed in those strange and maybe dark times we seem to be living in with so many global problems that we just don't seem to be able to solve and all those people, who are using the platform to spread harmfull information.
Times have never been as good. Most things are getting better all the time. You just don't hear about it on the news.
@
My comment isn't about what is, but about what's to come, especially if we don't address global warming, overpopulation, our ecological footprints and biodiversity loss.
One really has to be asleep to not understand the challanges and dangers associated with those problems. And we're nowhere near solving those problems. Quite the opposite we're currently showing that our system doesn't seem capable of dealing with those problems adequately.
The first 2 attempts you had the prop on backwards! The last design you had it on correct. As an RC pilot, this is something that catches my eye all the time!
Derek did the same thing on Vertiasium, too! It was so frustrating knowing that his model was losing a ton of efficiency for a simple reason.
Can I assume this is because the prop has an asymmetric bias for lift/thrust, like a wing?
@@ntsure2436
Exactly. Props (except for reversible pitch props used for very specific aerobatic model aircraft) have camber.
Running them backwards makes a lot of noise and a little bit of thrust, but nowhere near as much as when they are going the right way.
The concave side should always be facing backwards (so for a 'pusher' design, you have to mount it backwards with respect to the shaft).
I was looking for that comment :D
Buggered me as well.
Otherwise an awesome build, so nice that it's open source and essentially anybody around the globe can build it. Well done!
I really truly didn't think it would work! I was more on the "it's bunk" side of the room. Thanks for sticking with it!
Thank you for creating this my daughter is really into stem and really loves you
Xyla Explained STEAM as "Science, Technology, Engineering And Math" I'm pretty sure its, "Arts and Math"
@@petersonners4626 It's STEM. There is no art in it.
This whole thing has become like a physics rap battle lol, you guys even pulled Neil Degrasse Tyson and Bill Nye into it 😂. Good work helping to settle a decades old debate!
@@manaherb6 youtube
And don't forget Sean Carrol
It was settled decades ago. Professor Drela made it clear that the equations have been used for a long time to eliminate the exact issues that UCLA had in his truncated calculations.
Only needed Newton to crush both
Like erb
"It's like the spherical cow" should be a marketing slogan
On an unrelated note, I'm glad to see the cow jokes transcend language barriers. In Poland we often assume cows are perfect cylinders for moment of inertia calculations in high school. That "spherical cow" was the first time I heard about it in English. It doesn't quite refer to the same thing, it's more of a principle, but there's also a cow! :d
@@Nabuchodonozord "Consider a cylindrical cow." ?? Why would anyone want the moment of inertia of a cow? Even if you are interested in the variable power requirements for rotating milking stalls you surely can treat the cows as point masses.
Or can you? Damn... I'm sure I did when I constructed an exam question about milking stalls but now you've made me think I might have over simplified.
Not heard of the spherical cow before - I always thought it was a spherical chicken..!
R
When I studied physics, it was the spherical horse.
I don't know about that, but that's going to be the name of my new band!
9:48 - If you want to reduce the friction even more, pry out the shield in those ZZ rated bearings, wash out the grease and add sewing machine oil. That or get some fidget spinners and steal the bearings out of those.
"you can go downwind faster than the wind"
People: :0
Me, a sailor: ok yes
(Yes I know that this is different because it's _directly_ downwind and not at an angle, but from what I understood of veritasium's video, it's really the same concept because it's the prop blades that are angled)
yea i remember derek's perfect 3D animation of two sailboats going round a cylindrical ocean - that's what sold me the first time.
This is how I understood it... What's the problem? A ship can go faster than the wind? The answer is YES !! The propeller has high torque but LOW velocity and the wheel has low torque but HIGH velocity... So there's no extra energy, the Veritasium ship can do it !!
You, sir, get it.
Yeah, this explanation was hard for me, but Derek's video with the cylinder earth was like, "Ohh okay, that makes sense".
My mechanical teacher always told me. "before solving anything, make a drawing and make sure you draw ALL the forces"
Guessing ur teacher would propably draw force of the treadmill, in this one :)
Ends up drawing all the mechanical components in the treadmill
@@bobikoart 🤣🤣🤣🤣
That treadmill setup was what made it understandable to me how this could work.
It's looking at the original problem in the rest frame of the wind.
It doesnt work, as putting it on a longer treadmill will rapidly demo
Matt spot on its not the same essentially its running with an equal speed tailwind
@@kwinterburn
But you can’t exceed the tailwind.
In fact, minus friction, you can’t even keep up.
The closest to this is traveling by air balloon; you’re traveling at almost. Wind speed, so you don’t feel a breeze.
@@kwinterburn That was the aim, but the device does not actually work, as a longer belt will prove. Just as 37 rain said above
@@37rainman it would and it would accelerate forever. There is a little problem that nobody seems to pick up though....it is not the relative wind moving it, it is the motor of the threadmill that supplies that energy that allows the model to accelerate. A better experiment would be to put the model in a wind tunnel and see if it would accelerate. It wouldnt.
I'm a reasonably sciencey guy but.... I can't wrap my head around the physics of this (and I saw the original full-scale build).
Thank you for being a fun inspiration you people who are interested in science. A 20-minute video like this is worth more than a semester of boring HS science classes.
Congratulations on the successful build! You're right at the top of the makers I've found this year. I hope the colab with Veritasium brings you many new subscribers and gives you momentum to make more amazing things.
Well done! Oh, and yeah, we (model airplane pilots) always scrape, or sand, that mold line at the edge of a nylon/glass prop before putting them on the plane, especially those grey APC props. I've seen guys put one on out of the bag, hand flip it to start the engine and lay their fingers wide open on that sharp edge.
What he said
Get rid of the molding flash
You know what they say. "no project is complete until you bleed on it".
It was the blood sacrifices which made this project work.
Equivalent exchange
@@juanfrancisconavarrorodrig567 Just be careful not to lose a finger. It might end up as a homonculous!
Magnificent. I shared your stuff, especially this one, with my grandson who is finishing high school and had decided he wants to be a maths and science teacher here in Australia.
Shhhhh..... I couldn't be more proud. (Yes, he knows how excited and proud I am about it.)
As a 20-something yo engineer myself, I certainly feel represented by the Veritasium fangirling on this video. Awesome one!
Are you unsure of your age? Or did you just say 20-something for posterity's sake. 😊
@@JohanFroloff81 haha I said 20-something because I don't know Xyla's age and it's probably not the exact same as mine 😅
I usually say 20+ y/o. I mean, I'm 20+10+x right now but still 20+, yeah? 😂
It's so awesome to see the way you kept engineering through different iterations and never giving up! Kudos Xyla!
That expression of wonder from Derek’s assistant was pure peak physics/engineering crossover
Xyla, I love how you explore soooo many creative avenues. Rockets, Wood, Science, . . . Please keep sharing.
Awesome, and great to show the iterative journey of engineering!
One little detail to maybe add: I noticed in Derek's first video, when he used the cart as an explainer prop, that the propeller was mounted "backwards". Most propellers are asymmetric, and have preferred direction. The more rounded part of the blade should face forward, the more hollowed side backwards. As a model airplane builder, it instantly stood out to me, but isn't super obvious otherwise I guess. It seems, watching these two new videos now, that this might have been a confounding factor in some of your earlier versions, additionally to the prop size and pitch - "backwards" the prop efficiency is much, much worse, very ineffective. I was about to comment on it on Derek's initial video, but I didn't, as I thought it doesn't matter, and nobody will read it anyway... now, after seeing how much was at stake beyond just a video explainer prop model, I feel a bit bad about not commenting on it back then! In any case, on the final cart it was right, so you probably figured it out already. Just thought it might be good to know for people who want to replicate it :)
This caught my eye as well, also came here to comment the same thing 😁
I'll add here another thought for simplicity: A general rule to RC props is that the text on the prop should be facing the forward direction of the model 🙂
Dont worry bud, you werent the only one to notice. I posted a comment, only for it to be lost on the void. The prop backwards kills thrust, by a lot.
@@vanguard6937 The idea behind the backwards prop is to convert the power of the tailwind to a propulsive force on the driven wheels. Similar to the principle behind any perpetual motion machine.
@@johngraves2942 it would still be backwards, even if the wind (from behind) would be what spins the prop 🙂
I noticed the same... and it was present in almost all versions except by the last one
If you're not a pilot, or enthusiast, or mechanical engineer, you might not know that the main axle is going to want to rotate with the tail wheel dragging if the center of gravity is behind the axle. That's why you get that left right sway. It's also an important thing to consider when loading uhauls and trailers. And if you see that guy with trailer swaying like a mofo. Now you know.
Want a TH-cam example look up "ground looping".. so it would be more stable with the main axle in the rear and weight in front with small nose wheel.
Good stuff
/watch?v=APcpp3wFZjU
Does not apply ... dynamic forces are different ... it's not powered above the axle but through the axle and 90 degrees to it ... not a puller prop ... angle of pusher prop is down through the front axle, there is a force through the prop shaft down into the front axle ... there are 4 equal size wheels that do not swivel (tail draggers the rear swivels, it's mass is much lower, the radius is much smaller) ... planes generate lift ... the angle of motion is in the direction of heading. Ground looping is predominately due to the latter, when the heading is different from the direction of travel.
Think precession ... the turn causes the torque ... the torque doesn't cause the turn. You have to think of it more as if it were a sailboat with a keel mixed with a helicopter. The advancing port side (Left side) of the prop has more resistance because the prop (clockwise rotation) is at an angle in the direction of motion. The Starboard (Right side) is receding and will have less resistance. Think of why a helicopter has a tail rotor and a sail boat has a rudder. Yeah they are there to steer ... but also to counteract the gyroscopic and inequality of resistance forces.
Regarding trailers ... the force that creates the sway is ahead of the axel at a pivot point and also due to rolling resistance (one tire under inflated, bearings shot, different tread, tire size, etc). An axle forward of the center of gravity unloads the pivot point and creates a greater steering torque around the axle giving more momentum to the mass behind it. The contraption in the video has the pivot point at the axle not ahead of it. Planes in the tractor (pull) orientation are the same, the pivot force is ahead of the axel. The only 4 non pivoting wheel trailers I've seen are on railroad tracks.
I'm perplexed how you would put the main axle with the prop at the rear while having the smaller wheels in the front with most of the mass unless you unnecessarily added it there.
@@ejrupp9555 after misloading my ATV's on my trailer *once* and almost putting my truck into a guard rail when younger. I very quickly learned proper loading :)
Also: if the center of mass leaves its base, it'll fall over: the scientific reason I cant ride a skate board..
That "Yooooooo!" at 14:21 is so adorable.
I just want to appreciate that the final build purple and the shirt you're wearing when it works sync so nicely.
Xyla’s Excited “Eureka” Face 😃 never fails to brighten my day
14:20
it brightened my entire month 😁
Watching this whole series has been amazing, awesome collaboration!
I loved this look in to the struggle to prove a concept that you were assured worked. Just changing a few small parameters matters. Great video!
Xyla,
Great Job with making a working model to prove a difficult concept, Thanks for sharing.
I have a few comments that may help others with the formula given as not being an engineer I could not follow exactly how you described the formula.
Formula given: (Propeller distance / Wheel distance) must be less than .7.
What does the propeller distance means?
“Propeller distance” means the distance a propeller will travel perpendicular to the propeller rotation in one full rotation. This is determined by the pitch of the propeller. In this case a 4.7 pitch propeller is used so the propeller will move 4.7 inches in the direction the vehicle is moving after one full rotation. (Since the propeller on this vehicle is not perpendicular to the ground this will not be 100% accurate.)
“Wheel distance” means the distance a wheel will travel in one full rotation. This is equal to the diameter of the wheel times Pi or approximately 3.14159.
So 4.7 inches (distance traveled by the propeller) divided by the wheel diameter X times 3.14159 (or Pi) must be .7 or less.
To find the minimum wheel diameter set formula to = .7
To solve for the wheel diameter, (Propeller Distance/ Wheel diameter X 3.14159) =.7
First multiple each side by the wheel diameter or X to get the wheel diameter on the other side of the equation.
So .7X = 4.7/3.14159, Next divide each side by .7 to get the wheel diameter by itself.
X = 4.7/ 3.14159 time .7 so X = 2.137” minimum wheel diameter.
I hope this is accurate otherwise I’m sure others on the site will let me know.
Thanks,
Greg
Man, I love your enthusiasm on these projects you do. It's infectious. Great content from a great channel. Oh.. and by the way my daughters think you're awesome too :)
Xyla’s involvement in this project is phenomenal and how intriguing that she fabricated and built it herself.
I'll be honest. I got more excited over your appearance in Derek's video than I did for Bill Nye AND Neil deGrasse Tyson' cameo. Your work is so awesome!
You’re right. They were both fairly pointless in the video.
Yes, it is possible for a wind-powered vehicle to outrun the wind it is traveling with under specific conditions. This concept is counterintuitive but has been demonstrated through a principle known as downwind faster than the wind (DWFTTW).
How It Works:
1. Mechanism:
The vehicle, like the famous "Blackbird" cart, uses a propeller connected to its wheels via a transmission system.
As the wind pushes the vehicle, the wheels drive the propeller, which generates thrust. This thrust propels the vehicle forward faster than the wind.
2. Key Idea:
The propeller is not just passively driven by the wind; instead, it acts like a fan, actively pushing air backward.
The power to spin the propeller comes from the movement of the vehicle's wheels on the ground.
3. Energy Source:
The wind provides the initial energy. Once the vehicle gains momentum, the relative motion of the wheels powers the propeller to push the vehicle forward faster than the wind itself.
Demonstration:
In 2010, Rick Cavallaro's Blackbird cart demonstrated this phenomenon. It traveled 2.8 times faster than the wind in a controlled environment, confirming the concept.
Why It Doesn’t Break Physics:
This phenomenon might seem to violate the laws of physics, but it doesn't. The system relies on clever engineering to harness wind energy more efficiently. The key is that the vehicle continuously extracts energy from the wind relative to the ground.
Another significant change you made in the final version was lengthening the vehicle. In the earlier versions your propeller was pointed more downward, so more of the force was directed into the ground rather than to pushing the car forward. Just eyeballing it (based on the geometry of the cars and a bit of trig) I'd guess that the wasted force (maybe 10% on the earlier version) is decreased by 30-40%. Basically you're gaining a few percent thrust with no significant cost. The blackbird, or the earlier vehicles that were built in the 60's - 90's, had a bit more gearing to get the propeller completely horizontal. I understand why you didn't do that, but the smaller angle does make a big difference.
smart words
In the earlier versions the propellors were on backwards.
Thiiiis
Getting the prop thrust vector to be 90 degrees would yield better results yet, but gearing friction loss would probably be a wash.
@@clayz1 Good point! Maybe larger front wheels -> higher axle -> lower angle of attack?
This is so ridiculously cool, Xyla! 🙀 Incredible engineering & stunning aesthetics!
One of the things I admire most about your work is that so many of your creations could stand alone equally either for their engineering merit or their artistic value. A lot of people create functional things that also look nice. But with you and your creations, you are truly an incredible artist in every right just as much as you are a phenomenal engineer.
your name spells "S.Ingle" lmaoo
@@Goldy01 yeah that made all my school email addresses really interesting
Can anyone be a good Engineer or Mathematician without being Artistic-holistic?
@@davidwilkie9551 Of course they can, but generally do not stand out among their peers who achieve both without limiting the max potential.
Jeez you write some serious essays
Great video Xyla. I just ran across you on Veritasium's video. Smart, funny, personable and persistent. I loved the way you laughed when the models failed, made modifications until success... and then "exploded" upon that success ~ just a lot of fun to watch. A great example to all the young and upcoming tinkerers out there (which is where a lot science starts)... I think I will have to subscribe.
I’ve been working with my hands my whole life. You’re right hands on is amazing. BTW you are amazing i love your channel.
This channel is absolutely amazing, I'm lovin this girl and her content, what the hell TH-cam, why wouldn't you recommended me this before
I'm so glad veritasium has introduced me to you.
_"All these people just need to learn not to put their appendages where propellers are."_ -- Xyla Foxlin, 2021
I have worked in aviation for a few decades, and I THOROUGHLY APPROVE this quote...😊
BTW:
*TAKE THAT, ACADEMIA!!!!*
😄😄😄😄😄
She's an airplane pilot.
Well done, as always! And "Pog!" as suggested on Integza's Discord! =) (Disclaimer* I'm a "Xennial" so I often don't get the context of words like "Pog," but I looked it up on Urban Dictionary and it had mostly positive connotations, Integza seems like a pretty cool TH-camr and likely has positive intentions, and I personally intend it in only the most positive way!!) Keep up the good work! =)
Neat! well done
I have a thought on these treadmill tests in general.From comments i see on other videos ,it's obvious the treadmill test screws with people's brains!
Most would be better off watching the full size Blackbird.It saves one whole extra layer of complication
I agree. Humans don't understand relative motion until they're trained to.
The ‘A’ team. “Love it when a plan comes together” perfect guys
thought to watch this when I watched Derek's video but actually forgot it as I was excited about the SciComm Contest but finally watched it! What a beautiful Engineering! And obviously Rick is literally a genius.
Incredible!! I just watched Derek’s video and finished watching yours. I follow several engineering TH-cam channels and yours is definitely one of the best. Great job.
14:45 "Do you wanna play with it?" This is the core of the scientific/engineering spirit ^_^
Dereck 3 am:
"_Oh no, it's the treadmill maniac girl again..."
But really…
@@veritasium I need to save this moment
You, or someone, for instance kiwico, could make a kit for this, with and without 3d printed parts. -edit typo
Great idea
A feeding frenzy for lawyers representing those who get a cut from the propeller...!!!
This sounds awesome!
@@beaksofeagles grumble-grumble stinkin' lawyers...
kiwico?
I'm sure people tell you all the time they love your energy. So forgive me for saying the same. I used to date a girl who was equally energetic, who used clever puns in her speech, and, believe it or not, who had a strikingly similar voice to you. She was a joy to be around, always lifted the spirits of anyone in her presence, and was incredibly inspirational. I think I created more art during the one year we dated than in the 10 years after. I loved not being the smartest one in the room, though she never intimidated anyone because of her light-hearted and silly demeanor, and I constantly found myself learning something new from her. I supposed what I'm trying to say is all of these wonderful qualities pertain to you as well. I've watched nearly all of your videos and am thoroughly enjoying your channel.
Hey, I am sure someone probably told you this but for the first two versions of the cart, you had the prop flipped backward. RC propellers are only designed to be spun with the numbers for prop's size and pitch on the side facing the same direction as travel (unless the prop was designed for clockwise motors or backward facing counter-clockwise motors). If you have them flipped incorrectly they still generate force it is just far less and is very inefficient.
Saw the prop and looked in the comments.
I think no one yet has understood that it is the Bernoulli principle and not air being thrust it out the back. I was kind of surprised that the contract was signed by physics majors.
@@rcmrcm3370 You will never find a prop that makes thrust without sending air backward :)
Wow, I genuinely appreciate the effort to replicate this and especially to make it reproducible by other people. This is what science is meant to look like.
What this does is specifically test the good professor's belief that the treadmill case will falsify the land-racer case. I find the treadmill case dead simple and altogether transparent, but if we want to translate it to a more side-by-side comparison to the land-case, let's take a rugged 100m strip of 1m wide treadmill rubber to the land-course and pull it behind a car, using a second car holding a wind-screen out sideways ahead of the model. At least as a gedankenexperiment, because this sort of thing is beyond my resources. Perhaps Adam Savage might want to pull it off-so to speak-some day.
Will the result match what we see in the video? Yes, all things being equal, it should. Our model is going to keep advancing until it reaches the car, and it's very obvious why. The gear ratio and the constant supply of energy guarantees it.
It is not analogous to the wind-car arrangement proper.
@@-danR Some such scenario might be interesting, but that one isn't quite it. The treadmill belt needs to move rapidly rearward with respect to the cart. (Well, I mean, rearward with respect to the air, so then even more rapidly rearward with respect to the cart when the cart starts making its way forward through the air.)
Derek advances to ElectroBOOM's level here, for science.
Dam IllidanS4 that made my day
LMAO
Bruh
What's the small structure with lights at 11:50?
@@netsider th-cam.com/video/j5v8D-alAKE/w-d-xo.html
Pro tip for cutting aluminum tube for future use.. use a utility knife and with the blade pushing where you want your cut, roll the tube back and forth.. 4-5 rolls later and your start cutting the tube
it looks really, cool. particularly because it is so mechanically simple!
But does the prop rpm actually stay the same or increase as it travells against the treadmill ?
:)
The propeler and the wheels have a constant speed ratio so as the car accelerates, the wheels turn faster and the propeler turns faster.
I use to build wind powered vehicles, until I took a propeller to the knee.
Ah sweet old Skyrim
Take me back to the days of the knee memes
I understood that reference !
That made me happy.
@@BadhonPinak Serious Steve Rogers energy.
as an engineer, I say that your videos are really incredibly fun!
Totally awesome. Congrats from a "self taught, backyard, small engine mechanic". I am 65 years old in body only. At S.A.I.T (Canada) 46 years ago we learned about the perpetual motion machine.
I think it's so awesome that you were mechanically failing because you were trying to make it accessible to your audience to build. Libraries are starting to host 3d printers. I hope more come to public access. If you have some local workshop in your town they will probably have one too. Go out and craft!
My high school got a grant for one in 2014-15, when they started to become popular with the general public. Super cool, my district wasn't well off, so it was a big deal.
I would hate to have to take care of a 3d printer in a library. I have 5 of my own and no way would I want Joe Blow to just use them.
Somebody please buy Xyla a drill press or a Bridgeport before she punctures her hand!
But she knows not to put her appendages where blades are.
I used a drill press in high school and I would absolutely love to have one, but I drill like Xyla does. I always stop and eyeball to make sure that nothing's in the way before I drill through something.
Yeah nah ... she's an engineer not a buffoon like the rest of us, she'll be fine.
Looking at the wounds, someone forgot to give their kids the "high speed go rounders are always trying to kill you" speech. Is that speech only something farm kids hear? There were a lot of speeches of this nature. Basically, all farm equipment, power equipment, water, electricity, and other forms of active or stored energy can and will attack without warning. Shark Week draws viewers, but Cow Week kills more.
Fun video. I wish I had the time to play like this, maybe when I retire.
Fantastic, great video. My dad is a Physics professor and loved it.
A roller furling sail would help speed off the line. Once take off speed is achieved it can be rolled up.
So now that its proven, there needs to be a yearly competition to see who can make the fastest/lightweight/interesting cart. Just need a really long treadmill!
Nothing is proven until the treadmill is disconnected from it's power source.
Well, if this works as it should, all you need is a very long and flat surface and enough tail wind to get the craft up to speed.
I could see this being a thing in one of those salt flats.
It was proven years ago.
@@Eagleizer the treadmill is an exact analogue to a tail wind. its like watching the cart from the reference frame of the wind, the ground appears to move. If you disconnected the treadmill, the "wind" would quickly die out.
Would be more fun to have head to head races across a big stadium floor with some fans blowing from one side to the other. I know it can be done. I've seen indoor RC sailing races.
Question:
Wouldn't it be better if the prop would be rotating parallel to the floor?
That angle does make you loose on thrust - in my guess - of about 20-30%
That was my thought too.
I think it would too. My hunch of why it was not done as such is to reduce mechanism complexity and avoid the resultant frictional losses.
Edit: Upon further reflection, making the propeller tilted downwards had another benefit too. Noticed that she added rubber rings to the wheels? Apparently it had insufficient traction. That rubber provided more traction. This angled propellers introduced downforce which also helped to increase traction.
The actual rideable vehicle had propellers parallel to the ground. The vehicle was heavy enough that it had no traction issue. Best to angle them parallel for maximum forward force.
Measuring off the video, the angle is about 16 degrees. Cos 16 is approx 0.96, so the angle of the shaft makes the thrust loss about 4%.
I guess a more complex gear and shaft system to get the thrust line horizontal would introduce drag and a similar loss, as well as being more complex to build.
In order to do that there would need to be a second set o gears to offset the angle more gears means more efficiency losses
I know what you mean, but you are on the wrong axis. Either the prop is perpendicular to the ground, or the prop shaft is parallel. I also wondered about that, but it would have added mechanical losses that might have exceeded the gains from the on-axis thrust. If I had to guess, using a piece of flexible tubing (like Tygon) as a drive shaft would have been the most accessible low loss flex, but it would have required 2 more bearings and the associated framework because both ends of the two rigid shafts would need to be supported. Another close design in terms of loss would have been a horizontal drive shaft with a pulley under the rear tower, with a belt drive up to a horizontal prop shaft. Again, each shaft would need two bearings and associated framework. The design she made has the fewest parts, and was very forgiving of small misalignments, thus probably has a better chance of being successfully built by inexperienced makers, which is a win for everybody. This is really just 1 step up from a rubber band powered balsa airplane.
Nicely done, thank you for that amazing experiment. One small remark: at 5.43 the propeller is inverted which gives a very bad efficiency contributing to the failure of the experiment. At 13:58, you got the prop in the right position. (I am playing with propellers for 45 years ;-)
5:28 The propeller orientation is wrong I guess. That might be the reason. Propellers consist of airfoils like a simple wing. If you place the propeller in the wrong direction, the thrust will drop to almost half the normal value since the trailing edge of the airfoil is facing with upstream air (in the tangential direction). If you want to use that propeller to push the vehicle, you have to change the direction of rotation in the opposite direction.
Same thing caught my eye, but for most of the video it was really hard to tell. Maybe some visual illusion made it seem wrong. But right after 12:00, you can clearly see the camber is the right way.
Disfruté mucho mirando como diseñaste y construiste el modelo... Eres un genio!
As a physicist, I take exception to this title!
We don't describe anything as impossible ☺️ x
At least two physicists did so I get to pluralize hehe! (My original title said Some Physicists but it was too many words)
@@xylafoxlin OK, I'll let it slide! 🤣
So many physicists have described this as impossible. I watched threads go on for 1000's of posts 12 years ago when Rick Cavalarro build BlackBird with physicists claiming it was impossible and a fake. Often folks initial reaction was outrage and that outrage seemed to generate a self-sustaining state that caused part of their mind to turn off and stay stuck off.
So glad I found your channel. 🙂
My 9-1/2 yr old budding engineer of a son is going to love it !!
At the success point, I would've gone to "ok let's see if it can go uphill on the treadmill?"
Oh that's a great idea, proving that it can maintain its speed on an incline would be saying a lot.
@@lukewei That would require a different gearing ratio
@@kholofelolebepe9637 It's more than gearing ratio... The thing is accelerating. But this is an interesting question. You'd have to increase the slope of the treadmill commensurate with the increase in speed of the model. It seems like there ought to be a limit to its speed -- but I'm not sure. You could tie a string to the back of it fixed to a stationary point; and then slowly increase the slope of the treadmill till it couldn't keep up with the incline.
@@KevinMcMahon-hy2kl Have ever ridden a bike with multiple gears or driven a manual car?.Then you will know that you will have to change the gearing in order to go uphill so you don`t stall. Blackbird is basically like a simple lever, and like a simple lever, you get more output force(Thrust) than the initial input force(wind speed),depending on the distance between the fulcrum and initia input force which is the torque, in this case the fulcrum and distance being the gearing ratio. The torque of the system still remains the same
@@kholofelolebepe9637 But it's not gaining its forward velocity through the wheels; it's actually transferring the energy of its moving wheels into forward thrust via the propeller. It's kind of like the classic MythBusters "Will a plane take off on a treadmill?" episode. Wheel torque doesn't have much to do with it. At a certain point though, the vehicle will be fighting its own weight vs. gravity on an incline.
That car will never stop if the wind always blowing.
Keep your awesome idea up like this perfect car.
-Pog
And now ur mission is click the like button
Also Tomatoes is disgusting
oh wow, did you still want a brand new 3d printer for work? i have seen you before
This guy is absolutely no idea to comment i guess
@@keikerjustin1905 i modified it and it look pretty nice
Dude would not last long as airport ground crew: watch out for the prop...never mind someone fetch a mop and bucket..😜
Hahahahahhahahahaaaa
Oh that's brutal lol.
15:40 Umm I'm pretty sure Derek should be thanking *YOU*. This video earned him $10,000 lol
Yes, but he said in his video that he would give it to charity, so he didn't keep it for himself.
@@masterluuk1 : True, but he still won the bet! (And bragging rights!)
@@masterluuk1 Not Charity, but giving it to support people with great engineering ideas!! See his competition!
Its just travelling backward on the treadmill actually. The 10,000 dollars should be refunded
@@patcr6200 ?