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 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
@@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.
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.
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.
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.
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.
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.
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?!
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!
@@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..
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.
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.
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.
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.
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
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. 🏴👍
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.
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…
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.
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.
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.
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.
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
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."
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.
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.
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.
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. :)
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.
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
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.
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
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.
OK I'll do my best to ignore issue #1 the large T name. back in the 00s I did parking lot racing, all my rc's had aluminum chassis. Get some skateboard sliders (sorry can't think of what exact compound these are) , and mount them so you're not scraping the front or rear of the box. I used to shave them very thin then wax them. Aka reduce drag from ground contact as much as possible sensored motor, this will give you the best launch, from the electronics standpoint. you're still getting a lot of "squat", suspension tuning and possibly even a wheelie bar might also help keep those front wheels planted and clawing. A lot of the "no prep" guys run a short course or 1/8th base, including the slash, so there's plenty of tire choices out there for high torque high traction launches. Seriously consider something other than Traxxas, and take a look at some of the chassis actually designed for high speed or no prep drag racing, it'll solve some of these issues you had to resolve right out of the box.
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.
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.
Thanks for the recommendation on the material...ill look it up. If I scale the rollout I would then need to scale the speed...so measuring 0-6 mph. I wanted a straight up actual speed comparison. Also, the 1 foot rollout is based on the staging light spacing at a dragstrip...not the vehicle size.
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.
Please try to do lap times on a rc track with this, comparing aero system on and off, and the best rc cars available (and why not, making it be driven by rc professionals) ahah This car needs to be a thing! Of course I subscribed ahah
Just a note: I think that the ideal fan control would be a combination of both throttle and strerring, maybe also combined to a factor derived from the g forces of the car. On my channel (this specific one) you can see I did a car mod for assetto Corsa which is the fastest car in any game. Basically it's so fast because it emulates the fan sucking by using a dynamic angle system for the wings. Of course being it a game I had a lot of ways of easily making any value immense. But I also met a ton of issues. The angle of the wings is controlled by many factors, reason why I was thinking at a function of every control and maybe also g forces. If well tuned it can improve by a ton efficiency and why not also performances. Though it requires a more advanced chip than the ones equipped usually in RC cars, I guess
Maybe you can introduce some kind of speed reduction scaling for the vacuum. The vacuum is good I am guessing for the initial 0-20mph but after that it simply adds drag and the body itself should create enough downforce once you have enough airflow over the chasis. A similar technology is where cars use an active wing i.e. it pops up for cornering, breaking and accelerating but pops down when higher speeds are reached.
@@tomedward8652 The weight the stability and the speed would couse it to flip. One bump and that's it. ruclips.net/video/g8XxQkXCmsU/видео.html In this case it flipped when the front wheels were not touching the ground properly he was going downhill. That caused the flip. The rc car jumps around a lot. If there is even slight wind it would flip.
I got a Arrma big rock and granite that I bet would destroy that Tesla in a drag race lol. And the big rock is on 2.8 proline interco super swamper TSL SXs mud tires. It's got a 4290 2250kv big block on a hobbywing Max 6 esc. All metal gearing all metal axles aluminum integy A-Arms proline big bore shocks a custom stainless steel wheelie bar that is highly adjustable a custom aluminum center drive shaft. I got brass weights in it to hold it down on the ground. The diffs are steel and aluminum custom ones I had made for me at a machine shop they also made my custom motor and spur mount and center drive shaft. So no gears are breaking lol. I put a Arrma Skinz Chassis protector on it and also a stainless steel chassis plate that's cut out so you can see the cool skin underneath it. ATM I'm running a Integy 20T mod 8 pitch pinion and a Integy CNC built steel spur gear 57T ATM. With the custom gears in the diffs with the pinion n spur gears with the motor n esc the big rock gets to 89.3mph and it can achieve much faster speeds I just haven't pushed it all the way yet but I will eventually.. and I been dying to race a Tesla 😂😂
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.
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.
Great video. You used ground effects just like Formula 1 teams did in the 70's to achieve maximum downforce. You mentioned that the skirts were rubbing on the ground and that's what you think is causing the stuttering. Why not try what the F1 teams did back in the day and make a skirt that could slide up and down as the car moves up and down? Also, I think the F1 teams used something slippery like plastic or wax to reduce the friction of the skirt dragging on the ground.
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
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.
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 !!!
Slippers really just aren't made to handle that much torque. The stock slipper is designed for a 5lb car, but this car was effectively 24 lbs or so. And it's running a motor that's way bigger than stock.
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.
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.
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?
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.
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.
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.
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
A sensored esc and motor would help prevent that starting stutter
Agreed and a stronger battery.
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.
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?!
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!
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..
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.
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.
Watching This makes me realise how much I want an rc car where wings pop out and you take off and fly it.
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.
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.
watched 2 vids randomly. Functional & explanative genius rc channel kudos!
Dibs on that rc when you're done with it. 😉
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
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!
Your channel is really underrated, great video!
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 :)
Thanks for this series. I really enjoyed this!
Nice project! I really enjoy watching it!
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…
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.
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
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
Intake guide vanes for your edf's would help increase vacuum with only trivial weight consequences. Nice work, huge Fan.
I was telling another rc speed run channel to do this a couple years back and everybody laughed. Thanks for making it happen!
2:01 Giving happiness powder to the car
really enjoying your content, keep it up👍👍
Thanks! Im Looking forward to more free time over the summer for more projects
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
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.
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."
We could definitely break the internet with a collab 😤
Hah you have some fun videos. What state are you in?!
@@EngineeringAfterHours thank you! I’m in New York
@@MikeStallone ahh man that's pretty far from Texas...gonna be hard to collab. Let me know if you have any clever ideas.
Brilliant, yeah I was going to say to take the camera off the back, great experiment 🤠
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.
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.
Kool man. Foam tire will help with grip but this is a cool concept.
i love that the roof of the rc car is literally a dirt bike helm
I just know this video will eventually blow up, possibly when the new Roadster releases
I live in the same city!!!!! It'd be awesome to watch this car go some day!
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
I did near the end see a scale . A scale below each wheel could help balance the car better . Awesome work . . .
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.
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.
Slash 4x4 is 65mph stock. It just takes longer to get there.
7:05
Gordon Murray and his Brabham BT46 fan car: ".... am I a joke to you?"
Maybe look for an abandoned warehouse with smooth floors. I bet that would help
Fastest outdoor vacuum I ever seen
stunning work
Foam tires prep and sensored miter and you got it
I have seen Just 2 of your video, and deam, you deserve waaaaaay more than 5k subscribers, good luck whit this Amazing channel
Take advantage of the fans, u could add a blown diffuser to the car giving it more downforce and even thrust. Cool Video!
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. :)
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.
Hoooo that's wzup! Nice man. Definitely subbed up ✌🏾
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
Try angling the fan output more towards the back to see if that helps with more forward acceleration.
This is glorious. You’ve earned yourself a sub my friend 👍
Thanks!
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.
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.
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
Reminds me of the vacuum race car from the 1970s.
Outstanding build, engineering/data presentation and track footage! Now all you have to worry about is the upcoming super-secret FAN TESLA!
This is awesome. You should try and implement all this on a Arrma limitless.
OK I'll do my best to ignore issue #1 the large T name.
back in the 00s I did parking lot racing, all my rc's had aluminum chassis. Get some skateboard sliders (sorry can't think of what exact compound these are) , and mount them so you're not scraping the front or rear of the box. I used to shave them very thin then wax them. Aka reduce drag from ground contact as much as possible
sensored motor, this will give you the best launch, from the electronics standpoint.
you're still getting a lot of "squat", suspension tuning and possibly even a wheelie bar might also help keep those front wheels planted and clawing.
A lot of the "no prep" guys run a short course or 1/8th base, including the slash, so there's plenty of tire choices out there for high torque high traction launches.
Seriously consider something other than Traxxas, and take a look at some of the chassis actually designed for high speed or no prep drag racing, it'll solve some of these issues you had to resolve right out of the box.
Just subscribed! Sweet rc !
God bless
Have you thought of using a sensored motor instead? They have less cogging at low rpm. Great video, like the level of details 👍
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.
im 1m 20s into the video and am already loving the mix of SI and imperial.
Hah...finally someone that appreciates the ability to work in multiple unit systems!
I come from the wefere newscast, Greetings from Mexico
Welcome from Texas! Happy to have you here.
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.
Thanks for the recommendation on the material...ill look it up.
If I scale the rollout I would then need to scale the speed...so measuring 0-6 mph. I wanted a straight up actual speed comparison.
Also, the 1 foot rollout is based on the staging light spacing at a dragstrip...not the vehicle size.
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.
It has a cap pack...may be too small but well see with the new motor esc
Make sure the centre of gravity is optimal, the camera gets good footage but huge amounts of drag
Please try to do lap times on a rc track with this, comparing aero system on and off, and the best rc cars available (and why not, making it be driven by rc professionals) ahah
This car needs to be a thing!
Of course I subscribed ahah
Just a note: I think that the ideal fan control would be a combination of both throttle and strerring, maybe also combined to a factor derived from the g forces of the car. On my channel (this specific one) you can see I did a car mod for assetto Corsa which is the fastest car in any game. Basically it's so fast because it emulates the fan sucking by using a dynamic angle system for the wings. Of course being it a game I had a lot of ways of easily making any value immense. But I also met a ton of issues. The angle of the wings is controlled by many factors, reason why I was thinking at a function of every control and maybe also g forces. If well tuned it can improve by a ton efficiency and why not also performances. Though it requires a more advanced chip than the ones equipped usually in RC cars, I guess
Haha I love the suggestions. If I weren't a terrible race driver it may be a good test. I'd love to get a pro to test it out.
@@EngineeringAfterHours that'd be amazing ahah
Great video!
Maybe you can introduce some kind of speed reduction scaling for the vacuum. The vacuum is good I am guessing for the initial 0-20mph but after that it simply adds drag and the body itself should create enough downforce once you have enough airflow over the chasis. A similar technology is where cars use an active wing i.e. it pops up for cornering, breaking and accelerating but pops down when higher speeds are reached.
Without it, it would flip.
@@quackatit - please reread my comment. It is the initial acceleration that makes it flip. It won't flip once above 30 or 40mph.
@@tomedward8652 Int this case it wouldn't work.
@@tomedward8652 The weight the stability and the speed would couse it to flip. One bump and that's it.
ruclips.net/video/g8XxQkXCmsU/видео.html
In this case it flipped when the front wheels were not touching the ground properly he was going downhill. That caused the flip. The rc car jumps around a lot. If there is even slight wind it would flip.
I got a Arrma big rock and granite that I bet would destroy that Tesla in a drag race lol. And the big rock is on 2.8 proline interco super swamper TSL SXs mud tires. It's got a 4290 2250kv big block on a hobbywing Max 6 esc. All metal gearing all metal axles aluminum integy A-Arms proline big bore shocks a custom stainless steel wheelie bar that is highly adjustable a custom aluminum center drive shaft. I got brass weights in it to hold it down on the ground. The diffs are steel and aluminum custom ones I had made for me at a machine shop they also made my custom motor and spur mount and center drive shaft. So no gears are breaking lol. I put a Arrma Skinz Chassis protector on it and also a stainless steel chassis plate that's cut out so you can see the cool skin underneath it. ATM I'm running a Integy 20T mod 8 pitch pinion and a Integy CNC built steel spur gear 57T ATM. With the custom gears in the diffs with the pinion n spur gears with the motor n esc the big rock gets to 89.3mph and it can achieve much faster speeds I just haven't pushed it all the way yet but I will eventually.. and I been dying to race a Tesla 😂😂
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.
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.
Looks like you crushed that goal...well done. Now how do you go bigger? Could you out perform a tesla race car?
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.
Great video. You used ground effects just like Formula 1 teams did in the 70's to achieve maximum downforce. You mentioned that the skirts were rubbing on the ground and that's what you think is causing the stuttering. Why not try what the F1 teams did back in the day and make a skirt that could slide up and down as the car moves up and down? Also, I think the F1 teams used something slippery like plastic or wax to reduce the friction of the skirt dragging on the ground.
Could also use bristles, although that would reduce negative pressure (increase?)
watch his previous video on active downforce. He already covered all your points
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
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.
Can pull down power on the fans after launch? Locked difs would help too
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 !!!
Slippers really just aren't made to handle that much torque. The stock slipper is designed for a 5lb car, but this car was effectively 24 lbs or so. And it's running a motor that's way bigger than stock.
The lotus f1 that first used groun effect used titanium skids on the side that slid up and down within themselves .
Wow this is good stuff
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.
Well done video.
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.
Have you tried softer springs on the rear and add a wheelie bar so your not spinning as much
i dont even own any rc cars, and this is amazing ! I hope you watched the arrma smoke an F1 car on carwow
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.
Great video, and damn this channel do deserve teh subs :D
Not sure if anyone has said this but the stuttering is cogging a sensored ESC would help.
Also need cap packs
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?
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.
hot racing steel spur, there are much better higher traction tires available. cool use of a stampede chassis👍