Thank you for the positive response to the video everyone! I really appreciate it :) I’ve just figured away of getting much higher speeds! I feel silly for not even trying this before as i didn’t think it would work originally. I’ve just hit over 650mph tip speed so hopefully they’ll be a follow up video soon. Thank you

Try a hard drive disk platter. They're kinda heavy but they're balanced really well. I think valve and the losses from it are what's holding you back

"aluminum foil clearly doesn't work - Let me try... ALUMINUM FOIL."

The fact that all these people in this comment section are being helpful and trying to propose ideas on who to achieve a commun goal is pretty cool and relatively rare. Great video! I want to see the project succeed!

When your tin foil disk exploded, it was experiencing 1400 g's of centripetal force around the edges. Pretty incredible if you ask me. At this rate, you might actually hit material limits before you break the sound barrier.

The rotor has significant pumping losses, it acts as a centrifugal fan. If you sandwich a disc closely between stationary discs it will go much faster, as less power will go to pumping air. That said, you’ll need a balanced, precise and stiff disc for the rotor. Beware that if you use CDs etc. if you reach failure the fragments are vicious. Gluing radial carbon fibre ‘tow’ will improve strength to weight but will be difficult to keep balanced. Pairing with a prop balancer for RC plane/drone props might get you there. Beware there will be vacuum generated either side of the rotor as it centrifugally removes the air, so side discs also need to be stiff.

The problem with using bigger and bigger discs is that if you double the radius you get twice the circumference and twice the speed but the mass of the discs quadruples because the area goes up with the radius squared. So it's probably better to go with a small disc and increase the gear ratio instead

the tin foil disk slowly disintegrating from the rotational forces at 3:50 was pretty cool. Mach 0.5 is still pretty impressive with lego motors and axles all things considered

Breaking news: Man built makeshift hypersonic missile using LEGOs making LEGO stock rise 1000%

This might be something useful which I learned from XKCD: The edge of a spinning disc can't go faster than the **square root of the specific strength** (tensile strength divided by density) of the material it's made of. So, to get a disk that can spin faster you need to pick a material that has some combination of stronger an lighter.

6:44 when the intrusive thoughts win

6:50 look at the black pins turning due to the vibration. Thats soo cool! Love it.

Amazing how the aluminum foil discs tear themselves apart. It would be so cool to see that happen in super slow-mo!

Most people are wrote about the loads but I think an important portion of the power is lost on the plastic axles and gears, their flexity reduces power greatly so maybe a design could adress that, also having lots of rotating things increase the intertia and cause air friction so decreasing the number of gears could work better, maybe some gears can be put in the same axle. Although as I think about it, inequalities of the motors also a problem for the system maybe flexity of gears is a requirement for alignment of all motors.

At 7:15, you can see the black rivets holding the frame, are rotating from the vibration, just thought it was cool

If you could laminate some aluminum foil discs together so the thickness tapers from hub to edge, that would help keep it from breaking under centrifugal loads. It looked like you'd maybe have enough power for that type if only it held together. Keeping it nearly balanced is critical, though, so my suggestion might be hard to fabricate accurately enough. The low weight of the foil may mitigate that, so maybe worth a shot.

This guy and the slow mo guys need to do a collab. Would be awesome to see the vibrations in the object spinning.

5:00 the ultimate weed whacker

you need very aerodynamic "arms", and as few as possible. Try just one "arm", balanced out by a counterweight. And the "arm" has to be propeller shaped, but with a flat angle, so it does not move air. Then try to find the torque vs speed curve for different gear ratios and use the setting with ideal power and construct "arm" length accordingly. And while centrifugal force gets better with increased diameter (if you want constant tip speed), air resistance depends on total area, so a smaller object at the same speed creates less of it.

I love how pins spinning from vibration at 7:07

6:37 sounds like a car

wonder what would happen if we just keep adding more motors and eventually make a propeller to try lift the craft

3:05 United airlines flight 232

6:24 weedwacker moment

4:40 the disc got so angry it destroyed itself lol

2:52… interesting how the aluminum disc shatters under immense centrifugal force. It reminds me of how TheSlowMoGuys did a video about this phenomenon showing amazing footage of what a spinning CD or Record looks like just before it shatters.

6:05 contraption sounds like black mesa anti-mass spectrometer

5:24 try more things like this, make crazy things that attach and spin on it like that, perhaps try and get such high speeds that it lifts itself up!

This is extremely cool! Sound barrier or not, I think you reached a world speed record for Lego.

The sounds that the foil discs made when disintegrating were amazing! Bit like a cyberman dying 😂

If you weren’t behind some kinda of shield, that was pretty ballsy. The Centrifugal force of that rpm range has to be insanely powerful, especially with those weights attached with a string, one blow to the head from a breakoff would be most likely fatal.

4:09 it sounds like a car!

6:38 you can see the pins holding the 2nd 5x7 frame spinning inside the pinholes. CRAZY! I liked that

That ending made me laugh so hard That disk was like "nope im out, not havin it today" 😂

A very valiant effort! But I think you'd need to optimize your rotor a _lot_ more than this to get to Mach 1. Something like a precision machined aluminum flywheel might do it. Also, maybe consider aluminum axles for the last few stages? I imagine they're better balanced, straighter, and will lose a lot less energy to vibration losses as you pass through resonance bands.

Fun fact: the sound of a whip cracking is literally the end of it breaking the sound barrier. The whip was likely the first man-made object to achieve supersonic speeds, even if only for a small moment

it might help to stabilize the open end of the output axle. I feel like the primary vibrations caused by unbalanced rotating mass are really holding it back

3:14 sound like my annoying neighbor car Yes his car exploded

The foil disc's are actually a great example of tensile strength of materials, and are a great way to show why Tesla's hydroelectric generator would never work on a large industrial sized generator scale. At the time of its creation no materials could take the centrifugal forces. For context the generator had a peak efficiency when spinning at ~45,000 rpm iirc, and when used with a disc similarly sized to our current hydroelectric generators at around 2 meters, the tip would be reaching speeds in excess of mach 13.

Spinning a bullet to the speed of a bullet and hoping a glove and/or sweater will stop it is my new definition of optimism.

8:02 sounds like a propeller airplane

As you can see in 2:34 you get the highest circumferential speed with small, stiff discs, maybe you can do it with a more stable disc of about 10cm! I keep my fingers crossed for you and thank you for the great content, I can't wait for the next video...

It like the way the foil one go "AHHH-" on take 3 (3:55)

I noticed something really interesting in the "tower assembly" you used in the later tests in the video: the bolts connecting the two segments laterally were spinning in their sockets! Could this be some sort of resonance in the structure, maybe even sapping away energy from it?

Try ironing the paper, it should help to flatten it out and minimise vibration issues

3:00 Looks like aerodynamic instability.

Having aerodynamic lessons in my studies, I think that the disk route is the most likely, with stronger disk (not kitchen aluminium foil, but thicker foil from industrial cakes, or sheet metal) and less flexible like paper : I would say that the linked weights and the rolling bar have the least chance, as they induce a lot of drag, because of the vortexes created behind them. In my opinion, the disk route is the most likely to work, as the disk, instead of running into nearly stationary air, will create a uniform (if the disk stays flat) boundary layer : a region between the surface of the disk and the stationary ambient air were the air next to the disk is induced in rotation by it and this rotation movement decrease the drag. The issue with the disks, is the centrifugal force (f(N)=mass(kg)*radius(m)*angular velocity(radians/s=2*pi*turns/s)^2) your disks shattered because the aluminium foil couldn't sustain the tension induced by the centrifugal force, you need a stronger disk, and as we saw, the paper one is too flexible, resulting in it flopping during the rotation, creating a lot of drag.

Model aircraft propellers routinely break the sound barrier (most the of noise you hear on high performance stuff). Those high speed composite propellers are balanced and strong enough to not kill you. Granted their positive pitch means they need several horsepower to achieve those speeds, but you should be able to find something with a shallow pitch. And EDF impeller comes to mind.

From the point of physics, I must tell that to reach the maximum possible speed, sideways from putting all the weight to the center and making maximum diameter, you must minimize the possible air resistance, bc on high speeds it's taking much of the power. That's why you made out only 124 km/h with those lego bars

This video just seems to prove that a bigger diameter is slower. Also, you need to use materials that have a terminal velocity higher than the speed of sound if you want to reach it. Also, the flatter and less warped the disc, the higher the speed it will withstand, before further deforming.

Vacuum chamber to go even faster?

7:55 airplane noises

4:55 lets get dangerous

4:15 Audi v10 FSI(tm) soundtrack

7:20 *the mosquito in my room:*

5:29 helikopter helikopter

That's so cool! 330 mph is incredible!

Try it in a vacuum chamber, pretty sure you can do it at reduced air pressure.

For those of you who don’t know, 0:46 that’s how cars work to get high speed.

30 years later we're going past the speed of light using LEGOS

You should try to put this in a vacuum chamber to eliminate air resistance. A lot of energy is lost to air resistance espaccially with the disc. I am curious wich speeds you will get to.

2:11 the ultimate papercut

You need a thin disc with a large diameter, thicker on the inside and tapering out towards the edge. Use lightening holes to minimize the weight of the disc and reduce the aerodynamic surface area to hopefully reduce drag. Or run it in a vacuum pot.

I love how the 17cm one sound like literal car engines lol

I have a cheat way to do this, attach a Lego technique piece to a supersonic aircraft:333

Wow! It's impressive that wheels reach such crazy speeds! 😎😲

You should add an aerofoil to the ends of the bar you spun, then calculate how much lift it makes

Watching these just makes me want to go and buy enough to make my own, I fear how much this would've cost. I have enough expensive hobbies already trying to make synthwave. This is so great though, I'm glad someone is doing the Lord's work. There are so many questions to be asked!

Try ceran Wrap (I don't know if I spelled it right). Its really light does not break as easy as the tin foil and if it's a disc it doesn't have a lot of drag. All the ropes stuff suffered from huge drag. I don't think it's possible with the rope because the drag punches them back if you are really close to the speed of sound and they will just pull back and reduce the diameter

Can you try spinning a propeller on that thing? Good video👍👌

Goal for the wheel is to have minimal surface and cross sectional area for the least air resistance while being strong enough for speed of sound spinning. The weight does not affect top speed for a given diameter and air resistance, only the time it takes to hit the top speed. Weight will increase moment of intertia, but that only lowers the acceleration of the disc, not top speed. Also there is a special diameter for each material which gives the highest speed. It’s a balance between 1. extra air resistance of a larger disc 2. Lower RPM for speed of sound

I would also recomend to wrap around the machine a wall .... as you have created for a segment. I am very familiar with turbine burst tests... it is quite surprising the amount of energy even a small mass has at those speeds... awesome vid

This might be much much harder the closer you get to mach 1. Planes travel at around mach 0.8 because it's the fastest they can go before air resistance just skyrockets. This is your main enemy here. I have a feeling you need a LOT more power to even get tiny things faster than the speed of sound. Plus centrifugal force will be astronomical at this speed as well. I wonder if it can be done though :)

Did you consider maybe a disc from an angle grinder? Also, for cutting foil, you might try it with heavier foil with lower tolerance, and a compass, maybe that will help keep it flat

take 3 is amazing to see how the disc just shrinks

Well done! Now make an RC car with that. Because of weight it will definetely go around 40-80km/h! I want to see it!

4:50 You do realise that now you have to make a technic whipper snipper? (Brush cutter for the non aussies)

can you make eletric scooter from lego? nice vid.

imagine aliens studying this piece of footage and going, "well this is an interesting way to disintegrate tinfoil "

My idea would be to have a circular vacuum chamber that a rod extends into, and then it has a string or something that rotates fast in the vacuum. Edit: the motor could rotate a magnet sphere, and the magnet sphere in the vacuum chamber rotates without needing to touch the other one, and the one in the sphere has fishing line or yarn or something that rotates in the vacuum. Edit 2: You could have the whole machine inside a vacuum chamber, with fishing line or string being rotated.

I recommend using the buwizz motors they have an output RPM of 2000 !!! Maybe that could help you reach the speed of sound, Thanks!

Cool. Would've liked to see more about the thought behind it. How the gears are assembled, how the plate is modified. Did you try more mass near the center, at its point of failure? Etc

if you were to ritate the big weed cutter sideways so that the holes are facing the direction of rotation, u would have significantly less drag

ahh yes, he has become so advanced with Legos he wants to make one go faster then some commercial aircraft. Love to see it.

I suspect you have quite heavy losses with those multiplication ratios, especially with those 64:8 gears. Using smaller ones will result in more complex drivetrains, but this will be more than offset by the cut in losses. In particular try to avoid using the 8-tooth gear as a driven member.

Try focusing on building a really stiff base structure. I think studded beams combined with plates are the strongest structures for these types of things and not some flimsy looking studless structure. Maybe even weigh down the bottom

thanks for the sound warning... my headphones (and by proxy ears) thank you!!

That foil spinning needs to be filmed in high speed! Looks like it stretches out, very neat.

What kinds of batteries is it using? You can get a bit more power out of Energiser lithium AAs. They can put out a max of 1.7v each.

Damn man that’s sooo fast I found the tin foil so satisfying as it got completely shredded 🤯 keep it up!!!😎👍

U know ur a scientist at heart when the thing flings high speed bits of metal out at all angles AND THEN U TRY IT 2 MORE TIMES!!! This reminds me of that skid comic about the mystery Lightning lever

You need too have a longer axel for the "spinning object", and have a beam above it stabilizing it. It is resonating for a while before finding it's frequency, so doing this would improve acceleration time + stability.

This looks dangerous. I love it :D

8:08 I will send you to jesus

To all the people suggesting to create some sort of vaccum in order to reduce drag I just want to say that if you reduce the pressure you are increasing the sound speed. So it is unlikely to reach sound speed in the vacuum since it is greater than the sound speed in a normal atmosophere.

I would love to see the flywheel car idea integrated into a form of launch control to assist an electric motor for a dragster build

Wonder if some sort of teflon coating would help

This is a super underrated channel. Love the vids!

Great video, very interesting experiment! It is very difficult to balance the weights as circumference gets bigger...

The physics is so unrealitic like Roblox, the disc that is shrinking when spinning