Non-sensored brushless motors have to move and twitch a little so the ESCs can detect the rotor position and start firing the motors properly. That's possibly your startup/launch twitch issue - until the car twitches and moves a little the motors can't go full power. Sensored drive motor might be the difference.

A few days later the SpaceX package was quoted as having a 1.1s 0-60 with those cold air thrusters. Got your work cut out for you! Awesome work, this is already bonkers.

I see people have already commented about sensored motors, you should definitely look into them though. It will most likely eliminate all the stuttering off the line since the ESC will already know the motors rotor position.

A sensored esc and motor would help prevent that starting stutter

Using a ground effect to improve traction is a great idea as otherwise you're limited to about 1G as the traction simply cannot exceed the weight of the vehicle. You do mention around the 10 minute mark an intention to throttle the fans to reduce skirt friction at launch, but throttling the fans with the motor will never work asnot only do you need to overcome the inertia of the fans and fan drivers once throttle is applied before you can start generating any downforce at all from the set up, but you also have to overcome the volumetric displacement within the skirt. My first thought when you mentioned the desire to relieve the ground effect for initial takeoff was to actually stage the ground effect system with an idle stage of maybe 30-40%, and then throttling it with the main drive as this will already have your fans in motion relieving the inertia problem, and starting you off with a mild vacuum beneath the skirt helping with the displacement issue. Another thing that could be done to reduce the displacement beneath the skirt is to fill some of it in with more material but that would both increase the risk of bottoming out and add weight that has to be accelerated and as such wouldn't be ideal. Not going to lie though, I'm stoked to see a ground effect system in use here, as I've been thinking the same thing for a possible challenger to the roadster if I ever had the money to build it. I'd be using a small gas turbine to generate power augmenting a small battery set-up to save weight and provide huge amounts of current to the drive motors when needed, whilst sucking air from beneath the vehicle and providing a small amount thrust to help get things motivated

Back in the mid 1970's, my high school replaced the old cinder running track around the football field with a RUBBER track. Maybe check some of the schools in your area and see if they have something similar that you can run on. Either that or maybe a parking lot that's recently been repaved with asphalt, to smooth out the ride. Don't know if directing the air from the ducted fans back in a horizontal line would help much, unless you're using that thrust to provide some of the downforce.

The drive shafts that you are running are an upgrade from the standard ones, yes, but not the most bullet proof option Traxxas provide. Search for the Steel Constant Velocity Drive Shafts available for the Slash 4x4: CVD part numbers - TRX6851R (Front) TRX6852R (Rear). Great vid btw- Love seeing 1:1 Automotive Engineering principles being applied to RC!

I would love to see how much faster or would run on a smoother surface like a school gymnasium or a roller rink or inside a big warehouse. I imagine the fans would work better giving you better traction and hopefully quicker times.

Watching This makes me realise how much I want an rc car where wings pop out and you take off and fly it.

Impressive to create a fast car that is NOT traction limited. Would love to see a even more powerful version. Seems like active low pressure underskirt is a high risk high reward strategy, just as in Formula 1.

Dibs on that rc when you're done with it. 😉

After your active aero videos and now this, I keep wondering how practical it would be to get some kind of active suspension system setup

Gordon Murray had some success with full size fan car. His new T.50 looks to be quite amazing.

Serious suggestion, can you mix the downforce engines and have them spool up as the car accelerates? As to reduce the stuttering and as the car starts to approach 3G the fans come on full.

Fastest outdoor vacuum I ever seen

2:01 Giving happiness powder to the car

This was done on a Le Mans car in the 70s, it was the chapparral 2J, it achieved such cornering grip that they banned the use of fans to create downforce. Funniest thing is that I only know about this because i spent 1000s of hours playing Gran tourismo as a child and read through every cars bio and history haha

Awesome video mate, loved every second of it. I have a few suggestions which will definitely help to reduce your time further. I would recommend getting a Castle ESC + Motor since they are sensored and have more power, this will eliminate all the stuttering at the low end. Switch out the Arrma tires to GRP S1 tires or even foams if you can find them, the traction is way better on those. For batteries I would look into Chinahobbyline G+ 70C. These are the best batteries for value in my eyes. I have an Arrma infraction and I managed a 0-62mph time of 1.79sec without any ground effect so I'm confident that you can manage a sub 1.4.

Quien viene de Wefere? 👀

When you test the suction of the fan, the suction could be more powerful than you calculated as the fans might produce more thrust with some airflow, compared to pushing static air. idk maybe

Great great build!!!!! THE “STUDDERING” on takeoff is called COGGING!!! It’s because you’re using a NON SENSORED kv motor!!! By going with SENSORED, the motor can begin acceleration from a dead stop IN AN INSTANT without “cogging”…. Sensored is a feature that allows the esc and motor to communicate with one another soo that the esc can KNOW the pol positions of the motors magnets and and distribute voltage in the proper sequence…> NON sensored motors is like a blind man with a walking stick, it needs to find its way…

About the part where any transmission bits get shredded, I can only quote Gordon Murrey talking about BT46B: "Our driveshafts really didn't like our 2G starts."

Cool! Tip: You can probably get better results by using a better car to start with. Check out 1/8 on road racing cars, like the Serpent 989 lipo version. That is serious race stuff and use way better materials and part design. Also the tires (foam) they use give much more grip. Especially if you use the softer ones (low shore values). I bet these cars do 0-60 in 2 seconds in standard race trim. Now add your fans. And maybe put some weight at the right place, on the front? Also, use high capacity and high discharge rate batteries +8000 mah. Lubricate the the tires with tire sauce to make them even more grippy.

watched 2 vids randomly. Functional & explanative genius rc channel kudos!

Dude seriously? I mean you're not serious really? If i didn't think the world was living in a dual, imaginary world already - This really takes the cake.

Awesome 👏 you have a new subscriber, loved the application of math and your clear and detailed explanation. Time to look into the rest of your work. 🏴󠁧󠁢󠁥󠁮󠁧󠁿👍

The stuttering at launch looks like something us drag racers deal with called "wheel hop", generally suspension and tires (changing from low profile like you are running, to large flexible side wall drag tires) are the solution. If you look at some of the slow motion launch clips, 12:30 for example, and watch the tire and road surface you can see the tire is actually slipping, more more precisely slipping for a fraction of a second, getting grip again, then slipping again. Look up "drag racing wheel hop" and you can get some good analysis of it for full sized cars you can probably apply to to your model but I would put money on that being the cause of your stutter at launch.

The stuttering at the start happens because of block commutation (how the esc switches the motor). A esc with Field Oriented Control has significant more torqe from a standstill (a VESC for example). Also VESCs support up to 12s voltage = moar powah babey.

I was telling another rc speed run channel to do this a couple years back and everybody laughed. Thanks for making it happen!

Thanks for this series. I really enjoyed this!

Quien viene por wefere? JAJAJA

I suggest to try and use hub motors. I've built one with 4x brushless in the wheels, and it had insane acceleration. Also greatly reduces wear parts and center of gravity. You got to choose your winding and pole count wisely though (i.e. the "electric" transmission)

i love that the roof of the rc car is literally a dirt bike helm

Your channel is really underrated, great video!

7:05 Gordon Murray and his Brabham BT46 fan car: ".... am I a joke to you?"

Brilliant, yeah I was going to say to take the camera off the back, great experiment 🤠

I did near the end see a scale . A scale below each wheel could help balance the car better . Awesome work . . .

Foam tires prep and sensored miter and you got it

I live in the same city!!!!! It'd be awesome to watch this car go some day!

this is nuts, my friend has the xo-1 and i thought that was crazy is it just me or the track seems very rough? is that on purpose for more traction? it seems that the car is bouncing a lot on the cracks

Well done. Loving your channel. I like how you show the trial and error in your video. I would recommend a castle MMX8S esc and motor sensored set up , that will help eliminate stutter on your start up . Castle systems are much more efficient. And again look at BSR foam tires.

really enjoying your content, keep it up👍👍

Intake guide vanes for your edf's would help increase vacuum with only trivial weight consequences. Nice work, huge Fan.

One thing to help stop the shuddering at the hit is braid the brushless motor wires together works wonders

Nice project! I really enjoy watching it!

im 1m 20s into the video and am already loving the mix of SI and imperial.

You should pick up an older 1/8th scale HPI nitro car and put an electric motor in it. Those were designed for the kind of speed and HP you are trying to achieve. The Toyota LMP car I have was 70mph out of the box.

Reminds me of the vacuum race car from the 1970s.

Instead of a 1 foot rollout, scale that down to your car's size. If you can test on a much smoother surface everything should work better. A high lubricity, graphite filled material like SGL Carbon Group Ridurid® V 1640 High Performance Graphite Filled Plastic might help to reduce the friction of the skirt.

Kool man. Foam tire will help with grip but this is a cool concept.

Hahaha love it when the gopro flew all over the place

Awesome content 👍 Actually I think the front wing does help with aerodynamics !

Do what they do in the Japanese mouse competitions: 4 quad props set up in reverse so air is pushed into the air and forcing it down that way. Your system depends on getting a decent seal between the skirt and ground, if the car lifts, the seal is broken and there is no longer downforce. The props would give constant downforce without relying on a seal.

Take advantage of the fans, u could add a blown diffuser to the car giving it more downforce and even thrust. Cool Video!

Maybe look for an abandoned warehouse with smooth floors. I bet that would help

I come from the wefere newscast, Greetings from Mexico

stunning work

The stutter comes from tuning. The start power on high is not helping you on low end torque. It would be better on the car if you turn start power to Low and timing to zero. Believe it or not you would gain more ground for what you are trying to achieve by changing the 6s into 3s parallel. change the 32 pitch gears into Mod 1 gears. A 40 spur would change the whole game. As you increase the pinion size you will have less spin or wheeling. All though it would be much easier on a 30 shore contact foam tire to absorb the bumps in the rough road and create maximum grip...... since you live somewhat around McKinney (Traxxas) I would recommend the rear tires that come on the new drag slash. it's a ultra sticky slick tire. But only on 3s. I live in East Texas and work in Southern Oklahoma. I drive by Traxxas every 2 weeks on my way to and from work. If you have any other questions feel free to give me a shout. Very cool video by the way. Interesting to see the science behind it all.

What your experiencing at launch it's called cogging. It's due to the sensorless brushless setup and the gearing you're running. When the sensorless system first starts up it does not know the rotor position or direction and is basically guessing. When geared very high the motor cannot spin quickly at the start so it stumbles back and forth trying to figure out the position and direction. The larger the pinion you run the worst this gets. This can be resolved with a sensored brushless system.

I just know this video will eventually blow up, possibly when the new Roadster releases

You need a metal spur gear, a sensored motor & a dumborc radio. Metal spur can take more power, sensored motor will give you a smoother start & dumborc radios have the fastest response time & most range that I know of & they're cheap. I suggest setting up the fans to power down the faster you go. They help with launches but kill your top speed.

Hoooo that's wzup! Nice man. Definitely subbed up ✌🏾

You need a capacitor pack to stop the stuttering at launch. Youre drawing a lot of extra power when you start, and the loaded capacitors discharging helps account for that.

Skip the fans... Add "sugar water" into lawn sprayer & spray the concrete, add traction compound to tires. I would expect better results...it's what we used in inroad rc racing.

Outstanding build, engineering/data presentation and track footage! Now all you have to worry about is the upcoming super-secret FAN TESLA!

i think even a 1 second flat 0-60 is realistically obtainable for this car, but only with a nice flat surface as it seems even with 19 lbs of downforce you still slid from bumps and this slows it down a lot

Wheelybar and a arrma limitless will do the work👌🏻

I would ditch the large suction plate at the center for a smaller one ahead of the steering wheels (centered fan blowing straight up) and use it as front spoiler also. The propensity to lift the from during acceleration will be highly reduced by the force being applied at a longer distance from the CG of the car (near center of body). A smaller suction plate ahead of the rear wheels powered by 2 smaller fans blowing straight up would also increase downforce mid body. These smaller suction plates will reduce weight while still applying the same dynamic down force load. My 2 cents. :)

Make sure the centre of gravity is optimal, the camera gets good footage but huge amounts of drag

The stuttered launch is due to wheel hop. Either: pre-load/stiffen suspension, or use better tires (preferably ones which balloon upon acceleration).

Great video!

Wow, this inspires me to build an all wheel drive electric vehicle, directly coupled to a turbo-jet that drives a big-ass three phase alternator and the inlet to the jet a partially regulated draw from the underside of the vehicle through a FOD trap. I just need a sponser with deep pockets that's all. LOL

Sensorless motors has a high probability of stuttering off the line(Often called cogging), especially when coupled with lower gearing ratios(Called high gearing in RC circles). But this makes me think that he should contact some of the RC no prep drag racers. They often do the 1:10 scale quarter mile (132ft/~40meters) in ~1.9 secs, and that's with 2wd cars. Some of the reach about 90mph at the end of the run, so it would make sense that the 60mph mark is reached much earlier.

The car honestly almost has KTM design language all over it and I'm falling

¡Se me antojaron unos waffles!

underrated youtuber

We could definitely break the internet with a collab 😤

I have seen Just 2 of your video, and deam, you deserve waaaaaay more than 5k subscribers, good luck whit this Amazing channel

This is glorious. You’ve earned yourself a sub my friend 👍

Really really dope.

You might want to try the gold label Hoons they're stickier than the whites but I think the no prep guys are getting faster launches already with wheelie bars.

The lotus f1 that first used groun effect used titanium skids on the side that slid up and down within themselves .

i dont even own any rc cars, and this is amazing ! I hope you watched the arrma smoke an F1 car on carwow

Has anyone done this before? Is there an rc car competition you could enter into? Id love to see more of this and other peoples designs.

Gordon Murray's new hyper car (called the T.50 and is the spiritual successor to the McLaren F1) is a fan car. He said it was extremely hard to engineer.

Even if I wasn't a mechanical engineering major and a RC enthusiast, I would still love this. Have you looked into swapping out tires? I haven't checked out your other videos yet but I tried GRP tires on my Talion V5 and instantly swapped to something else because of the traction.

Have you thought of using a sensored motor instead? They have less cogging at low rpm. Great video, like the level of details 👍

Try angling the fan output more towards the back to see if that helps with more forward acceleration.

Your stutter is wheel hop!

Just a idea. If you curve the exhaust duct more parallel to the ground and tapper it. It could possibly help with thrust.

the imperial math makes my head hurt

Wow this is good stuff

Foam tires with tire prep will launch your rc so hard you'll blow both diffs with a locked slipper.

Just subscribed! Sweet rc ! God bless

Bro you naild it

Need a Sensored Motor, AVC on, and use the Arrma Infraction Chassis.

Springs need to be massively uprated to put all the downforce on the tires. Also your tire foam is likley far to soft. More traction on the tires means less downforce needed, means faster. You should tie the fan speed to a speed sensor, so the fans slow down at higher speed, and set it to always be on the limit of traction. Sub 1 second seems possible.

a properly setup aftermarket slipper clutch would solve the studering along with a sensored moter and you could try softer rubber for the box bottom , keep it up !!!

i had idea of useing the wheels as the fans and use quadrant spacing with the suction like have the wheel inner diameter be a variable ducting fan like would make an air break with wheel rotation as well as pull air from ducted area under car so you could use each wheel to fine tune what quadrant of your car gets more down force or close them up for high speed when you dont want downforce and go fast open then up for braking and slow speed down force could have a gearing mechanism to rotate the fan faster when the wheel is slowing down as long as you are moving you can get down force from wheel rotation ...

you could rub some skateboard wax on the parts of the undertray that touch the ground, this might eliminate some of the stutter off the line