241% More Grip with a Fan Car and Ground Effect
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- čas přidán 13. 05. 2021
- Tesla Roadsters and the Tesla Plaid model are have amazingly fast 0 to 60 times, but I've built an RC electric Fan Car that I think can actually beat the real deal. In this video we will race the Gordon Murray Inspired Fan Car against the Tesla to see if a toy can be a Tesla.
Parts used for this build:
Original Car (this was HEAVILY Modified):
amzn.to/41cLE1L
Upgraded 6s Motor:
amzn.to/44Hjqzd
Ducted Fans and ESCs:
amzn.to/3NRUG1o
4s Batteries:
amzn.to/3NRV8N8
Silicone Sealing Strip:
amzn.to/42zO23H
Differential Build Kit:
amzn.to/42j0mWm
amzn.to/42ztclg
These are affiliate links so I may get a small commission from these at no cost to you. - Věda a technologie
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.
Was going to say the exact same thing. It is the sensorless motor causing the stutter
Yep sensors help with tall gearing for take off to
you're telling me he has turbo lag on an electric car? makes sense
That and this motor and esc is very bad for studders
Glad to see this comment; a sensored motor/esc will allow for much better phase resolution and virtually eliminate the stuttering from zero RPM. In addition, a sensored setup will allow for more precise timing adjustments resulting in measurable and more meaningful adjustments when compromising mid-range torque versus total efficiency on the last leg of the curve up to 60 mph.
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.
He’s also been promising full self driving for how long? I’ll believe that 1.1 seconds to 60mph when I see it.
I was going to table pushing for a better time for a good while then I saw this announcement too lol.
I'll need a new motor/esc combo to fully get there and that's a couple hundred...but I know it's possible to beat the 1.1s with a rollout...maybe even straight up
@@EngineeringAfterHours the gains you got just with the tweaks you did already were huge, I wanna see this showdown happen some day haha
@@Dave-so7sf the beta that's out right now is arguably the closest thing to level 4 or 5 we'll see in the wild for years from anyone, that isn't arbitrarily limited to x roads.
It's not that we're not there, just that regulatory approval will thankfully be a monster to acquire, promises notwithstanding.
Wider tires and get rc airplane motors 😮 that thing will be UNSTOPPABLE.
A sensored esc and motor would help prevent that starting stutter
Agreed and a stronger battery.
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.
"sensored motors for the win!"
~me, a guy who drives a max 8 sensorless combo
WOW HE USED SENSORLESS MOTOR?!
There is no much performance left out on the table omg!
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.
Thanks for this series. I really enjoyed this!
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.
YESSS
Low traction surfaces though. He'd be better off running on a well maintained drag strip.
I wonder if the sticky compound most at the start line would be too much for the drive train to overcome though?!
Nice project! I really enjoy watching it!
watched 2 vids randomly. Functional & explanative genius rc channel kudos!
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
I wish I had that for this video because the suspension has to be so stiff for the downforce
@@EngineeringAfterHours can you make tamiya mini 4wd aero dynamic effect? since the release aero body and aero chassis as well...
@@EngineeringAfterHours i can not find it anywhere... the best video is just blowing dry ice smoke in wind tunnel to see how air flowing. i feel not satisfied. sorry for bad english..
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!
really enjoying your content, keep it up👍👍
Thanks! Im Looking forward to more free time over the summer for more projects
Your channel is really underrated, great video!
Watching This makes me realise how much I want an rc car where wings pop out and you take off and fly it.
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. 🏴👍
Thanks for the kind words!
Hoooo that's wzup! Nice man. Definitely subbed up ✌🏾
stunning work
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.
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.
Thanks! I definitely want to get a castle sensored setup for this guy
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.
Intake guide vanes for your edf's would help increase vacuum with only trivial weight consequences. Nice work, huge Fan.
Dibs on that rc when you're done with it. 😉
Just subscribed! Sweet rc !
God bless
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.
Good advice, I'll look into the GRPs and the batteries as I've never worked with either of those.
@@EngineeringAfterHours You can usually find some discount on the batteries as well :)
Great video!
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.
Did you also notice how much flexing happens in the suspension components further worsening the wheel hop situation. You can see the wheels moving back in forth in relation to the chassis. Traction bars up front and trailing arms in the back would definitely help with wheel hop. Im not convinced its a motor issue as alot of people suggest, as much as it is a suspension/tire issue.
This is wrong. There may be some wheelhop but the stuttering is a non-sensored brushless motor characteristic we call “cogging”. Someone had a decent explanation in the comments.
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
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
Great video, and damn this channel do deserve teh subs :D
Kool man. Foam tire will help with grip but this is a cool concept.
Well done video.
Fastest outdoor vacuum I ever seen
I live in the same city!!!!! It'd be awesome to watch this car go some day!
Gordon Murray had some success with full size fan car. His new T.50 looks to be quite amazing.
But its not full fan car per say. It just cleans boundary layer in diffusor and prevent stalls at higher speeds. And makes using steeper AOA of whole floor.
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.
This is glorious. You’ve earned yourself a sub my friend 👍
Thanks!
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
That car was one of my inspirations for the project.
Have you extended the pan vacuum box forward between the wheels ? I think extending a small portion 2"x3" approximately will decrease the off the line vibration . You seem to have plenty of vacuum, and distributing the vacuum will help with other factors of load on take off.
Wow this is good stuff
Try angling the fan output more towards the back to see if that helps with more forward acceleration.
I did near the end see a scale . A scale below each wheel could help balance the car better . Awesome work . . .
Really really dope.
2:01 Giving happiness powder to the car
Awesome content 👍
Actually I think the front wing does help with aerodynamics !
It probably does give me a little downforce but it's got so much from the fans that I don't really count it
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.
Interesting...this can be done on a sensorless motor?
@@EngineeringAfterHours yes, it also Supports sensorless Motors. Although I dont know how good it works without sensors.
all sensorless brushless esc's rely on back emf (voltage induced by the magnets spinning by the coils) to sense the position of the rotor in it's rotation
sensored motors use additional magnets and sensors to directly measure the angle of the rotor
that has nothing to do with the commutation, which is what type of alternating current is used to drive the motor
the easiest type is square wave
most esc's use trapezoidial, there are a few that do sine wave commutation at startup and switch to trapezoidial and even fewer do full sinusoidial
the more rectangular the wave is, the more power the motor will produce, at the cost of smooth rotation
choppy rotation is most noticeable at spoolup, which is why some switch from sinusoidial to trapezoidial (smooth start, power when already going)
another factor is what pwm frequency is used to create the ac
the higher the frequency, the more efficient the motor is
lower frequencies create more power
some esc software use the rpm of the rotor to define the pwm frequency
Vesc also supports sensored motors, and has done high current stuff specifically designed for loaded start applications. I would definitely recommend checking it out.
Yeah I've been fighting cogging on my new stampede setup. My maxx does it with my bigger tires too sometimes
thanks for sharing :)
This is awesome. You should try and implement all this on a Arrma limitless.
I have seen Just 2 of your video, and deam, you deserve waaaaaay more than 5k subscribers, good luck whit this Amazing channel
Can pull down power on the fans after launch? Locked difs would help too
How much downforce do you generate via relative wind at speed? Can you reduce the under tray fan speed past say 40mph to keep your acceleration up.
I just know this video will eventually blow up, possibly when the new Roadster releases
Have you tried softer springs on the rear and add a wheelie bar so your not spinning as much
Bro you naild it
Brilliant, yeah I was going to say to take the camera off the back, great experiment 🤠
This video is great sir! I have a question though,what's the part # for the slipper clutch eliminator? Thanks.
The one I used it made by hot racing. I don't know what the part number is.
what if you put a button or some other trigger that can pre spool your fans at an idle speed but theyll still be attached to the throttle so they can spool up to full when the car needs it
One thing to help stop the shuddering at the hit is braid the brushless motor wires together works wonders
Yep...version 3 finally went brushless.
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
Just a idea. If you curve the exhaust duct more parallel to the ground and tapper it. It could possibly help with thrust.
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…
Maybe a vacuum bleed valve that can be controlled (adjusting how much vacuum the undertray can pull while keeping the fans at max speed) during the initial stage of the launch?
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.
I would make a servo controlled bleeder on the skirt and mix that in with the throttle ... the bouncing at the start is suspension / downforce related. Try adding a 3axis gyro and accelerometer to log that. But most likely your are rocking the suspension back and forward till it settles. My bet would be that the stationary pretention with the launching are having a little rumble.
ps: the bleeder will have "zero" lag as the EDF will be spooled already.
Have you thought of using a sensored motor instead? They have less cogging at low rpm. Great video, like the level of details 👍
One question. What is the reason to put the batteries and fan controller near the rear axle?
That was where I could cleanly fit them them as low as possible. I wanted the CoG to be low, and they needed to tuck under the body I had.
Could the stutter be from the drive shaft twisting under initial torque load?
I think its cogging of the motor.
Thought about a lcg chassis or shortening the shocks to have it ride lower?
Lcg chassis was ordered last week:)
you can use a little sticky surface to reduce wheelspin like in drag races
awesome!!!
7:05
Gordon Murray and his Brabham BT46 fan car: ".... am I a joke to you?"
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. :)
loved it
Is it possible to use conventional drag racing and somehow involve a trans brake to deliver torque faster than what the ecu can deliver?
It's probably possible, but with the upgraded sensored motor on the next build...I didn't need more torque.
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."
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 ...
Foam tires prep and sensored miter and you got it
SOOOOOOOOO SICK!
Should the 1ft rolllout be scaled down to the size of the RC?
No, you would only scale that if you were scaling speed down as wel
I have been looking to do similar on one of my arrma cars, where did you get the fans and more importantly the fan housings from? Thanks
The fans are 50mm EDFs from amazon. The housings I had to design and 3d print myself. They needed to be pretty form fitting for the packaging size I was working with
@@EngineeringAfterHours Thanks so much for the fast reply. I don't supposed you have the 3d files that you could send me by any chance? If you look at my latest video you'll get an idea of what I've got planned for the same setup. If you were willing to part with the 3d files my email address can be found under my 'about' page on youtube. I've watched this video 3 times so far this morning! I am thinking of custom making a chassis for my infraction with just this idea in mind
@@DriftomaniacsRC haha awesome...planning for it on the infraction? Where can I send you files?
@@EngineeringAfterHours Hi there's a link on my youtube homepage if you click the 'about' tab it'll show a link to my email. Much appreciated just watching your latest 'last' video!
Will a heavier car be better for that initial traction and be more stable. Seems power is not an issue. Larger tires?
No, this car actually is power limited and not traction limited. A heavier car will make it worse. I'm going to rebuild with a little less downforce and drag, while moving to a better motor setup
you gotta switch to drag compound tires like on the slash drag model. also, redirect those fans to blow out the back to add to the thrust of the car.
have you considered modulating the fan once you reach a certain speed. Maybe the additional downforce is not needed and may be creating drag?
If I had a small motor dyno I may be able to reduce downforce when I'm power limited, but I don't know of one that works for my setup
Take advantage of the fans, u could add a blown diffuser to the car giving it more downforce and even thrust. Cool Video!
Amazing
some of your stuttering is coming from the control arms flexing back to front and then unloading and springing back and a portion may come from the Slash plastic pan flexing a tiny bit also
Do you think this is possible with the Traxxas xo-1?
Yes, but as the weight of the car goes up. You needuch larger power plant, though the 1717 in the X01 may be enough
You should do a arrma felony downforce build! It would be insane!
The lotus f1 that first used groun effect used titanium skids on the side that slid up and down within themselves .
Dumb question but do real drag strips have cracks on their surfaces as well?
The stuttered launch is due to wheel hop. Either: pre-load/stiffen suspension, or use better tires (preferably ones which balloon upon acceleration).
It actually turned out to be an unsensored motor. Fixing that gave it great torque off the line but was still unstable.
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.
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)
That's... that's brilliant!
Can you also use the motors for effective braking? You could literally have a full traction control and stability system... IN A BLOODY RC CAR!!
Crazy stuff!
@@skylined5534 Yes you can... Full traction, full ESP, even assisted drift mode... All should be possible with a single Arduino. And all this is a car that fits in the palm of your hand.
Motors even are water tight (at least mine) so it's pretty fun in the winter
If you use a sensored motor and esc that should get rid of any stutter that is happening because I do know that those non sensored motors tend to be glitchy like that at low speeds or the jump
Just out of curiosity why not use the Traxxas low cg chassis and center differential?
I've got one on order. I just didn't include it on this build because things start getting expensive fast so I try to set a Max budget for each build. This one was already over $400 so I needed to break it into a few incremental attempts to fund everything.
@@EngineeringAfterHours oh gotcha. I wonder if Traxxas would help you since you seem to use their products allot.
Have you heard of a perfect pass? It's a piece of hardware that can help you accelerate reliably/repeatably which would really help with one big variable.
Quien viene de Wefere? 👀
I was always wondered if you can use vaccumes to make down force
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.
We've got that fixed for round 3! Stay tuned
Tekno m6 driveshafts should fix all your breakages, as for the motor, a castle or tekin sensored escape combo should help for the studdering, another tip would be to get hoons gold, those have even more traction