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FIND - A - TUNNEL (with a flat ceiling)

If anyone is interested in fan cars, the McMurtry Spéirling recently broke track records, proving that ground effect is very effective under the right circumstances.

James you MUST do a part 2 and see if you can get it to drive upside down! 🏎

There is a BBC documentary called "Gentlemen, Raise Your Skirts". About the ground effect cars Williams had back then. No fan but shaped underfloor and the skirts were spring loaded carbon strips that could retract up and down into a slot so they could touch the track surface and follow the imperfections in the track. Check it out if you can, it's awesome if you like those old BBC doc's.

Some suggestions: How about a skirt made from a brush? How about putting the ground effect tray on a separate set of suspensions from the main chassis? One irl example is the Lotus88 One I've been asking myself watching the video is what lead to the choice of a propeller instead of an impeller to evacuate the ground effect tray, as the latter is way better at producing a pressure difference?

I believe the Chaparral 2J had its skirt mounted to the suspension, not the chassis. This way the skirt stays flat with the wheels, and doesn't move with the body. Try mounting the skirt to the ends of the suspension near the ball joints, and I bet you'll have more consistent suction and longer lasting skirts.

High pressure flexible 'tubular' perimeter skirt, low pressure chamber: Forget the walls, replace the skirting with something akin to a hovercraft skirt, but with the skirting pressurized to keep it inflated. I also suggest a tough material, as it will be in contact with the ground at high speeds.

The issue was you locked the suspension out. You effectively cancelled out the mechanical grip of the car. In turn, you also proved the effectiveness of the design. Double edged sword so to speak. You must have heard of the McMurty special right? If not....bro.... where have you been?

the long awaited sequel is here

The Chaparral did this long before the F1 car you cited. The concept is valid but was outlawed because the fan throws stuff all over the following cars.

Fun fact. Gordon Murray (the designer of the BT46B fitted an aeroplanes altimeter in the cars so that it would show whether the underfloor was sealed. The drivers had a problem that the skirt would be damaged and they wouldn't know and suddenly find themselves going through a corner about 40mph quicker than they could without the ground effect and having a colossal crash. So if the altimeter was in the green they could push. If it wasn't they had to back off.

The original Lotus car had sideboards mounted on slots so they would always adjust themselves to be touching the ground. Your front skirt-board doesn't need to create a perfect seal to the ground. If it's bouncing on the ground it will be slowing your car down. Some of the F1 cars used broom bristles to create a seal.

If my memory is correct the seal was made in more than 1 over lapping section so the road contact area could be worn away then slide down to replace it. Eg had a total loss section that lowers as it's warn away.

Love to see this run on a basketball court where the floor was perfectly smooth. That would let it really corner. Seems like for the skirt, some thing pliable but durable like silicone sheet would be good. Great vid as usual!

From what I studied, the vaccum skirts on the bt46b were attatched to the suspension so that they'd always stay level despite the body movement.

"tea, obviously" James, engineering in the best British tradition.

This is extremely sick, and you pulled it off so well! I have been thinking about doing something like this since seeing the Formula Student car from ETH Zürich use a similar approach for reaching 0-100km/h in under a second. IMO it's impressive how much extra downforce you ended up getting in a straight line on this. To improve the seal on bumpy roads, maybe you could try a 3d printed flexible TPU base with a sort of skirt around it from thin PTFE that is too long and just bends out when the car is further to the ground, but then extends once it goes more above it or over a bump?

Why can't you make your skirt out of rubber? You could even use an old bike tire inner tube.

15:06 love the bangs and pops😂😂😂

I like this concept a lot. Maybe you should try door brush seals for the skirt. First they are flexible, second durable and last you brush stones away in front of the car.

You are so inspiring for young engineers/aviators. Keep doing your thing!

Active suspension with this on an RC car would be awesome!!!

Very cool idea. Now we need : 1. Formula car 2. Helicopter turbine 3.Gearbox conversion 4+ A lot of engineering Thanks for the video. Very interesting how you scaled down a previous idea and made it work !

The part you missed, or couldn’t replicate from the original fan car, was the skirts moved up and down inside a channel in the sidepods so that they maintained the perfect hight to the road all the time, the last time I saw one it was effectively a draft excluder bolted to a piece of plastic that sat in the channel. I’m also fairly sure they didn’t completely enclose the skirts at the front (and probably the back) of the car as that was how they drew the air in to create the vacuum. There’s no way this is practical to do on that size of car but maybe a bigger one?

the small bits of debris, gravel and overall road roughness at the scale of your RC car, would be similar to trying to drive a formula car on a 4x4 off road trail. perhaps try testing again on a smoother airport runway?

You've created the perfect home RC Vacuum cleaner, just install a bag for the dirt at the end 😂!!! I would love to do house keeping like this👍

I would also like to add that on modern formula one cars, the “vacuum chamber” becomes a lot higher the closer it gets to the end of the car. I can see that your vacuum chamber is a consistent height throughout and it reduces the total amount of possible ground effect because you aren’t making the most of the available area. My suggestion is to cut a rectangle on the bottom of the chassis and raise the roof of the vacuum chamber to increase the vacuum. Another thing that I’ve read a lot on is connecting the vacuum chamber to the bottom of the suspension and replacing the foam boards with a brush material and I would like to second that idea because it is a great idea to keep the vacuum consistent. I would also like to see you use a rubber seal like the ones used for car doors and refrigerators if you have the chance. And another thing, please make the exit for the air parallel to the ground because while you are driving, the small amount of air inside the vacuum chamber is crashing against the rear wall of the chamber before getting sucked out, so might as well replace the rear wall entirely with the propeller to reduce air resistance. This will also give you more vertical space to raise the roof of the vacuum chamber even further and make the suction stronger. I hope my ideas are of use to you, and keep making awesome content!

its always good to see him upload and it makes my day

The rubber squeegee from a wiper blade may have enough durability to last. It could allow for a small travel to be added back into the suspension to help with its jumpiness

Excellent video, as always. No theatrics, unnecessary sounds or emojis. Just a logical, well edited video. Thanks. Waiting for the next one.

@12:22 That's exactly why fans like in the Brabham was prohibited :D if it fails mid corner you just fly away :D

Fold of thin kevlar for the skirt? Maybe fibreglass but would be less durable. Also might get better results from an odd numbered blade fan?

Cut rubber strip from bicycle tube, and use it as floor vaccum seal for tray.

Make the skirts to seal the floor with a bicycle inner tube. You can cut in the U shape and create a double wall. This will copy the profile of the surface. Another tip is not to set the suspension so hard.

Just a suggestion but maybe you could get a leaf blower and blow off the road as much as possible to have a nice smooth and consistent surface to test on .. maybe remove some variables?... Love the videos keep it up 👍

The car is bouncing because you disabled the suspension

Damn it... It's all over the screen now 😕

to have the best effect, you have to attache the soft part of the skirt to the suspension triangle, Like this you can keep the skirt to a constent high from the ground. The skirt can be attached on one side to the rigid part (your aluminium board). And on the other side to a bar connecting the suspension triangle ( 2 tubes can be imbricated in each other so that they can slide and allow the suspension to work)

If you scaled up the small bumps and cracks in the road it would be like taking a life size F1 down a gravel road. Surprised it worked as well as it did.

Under a minute gang

So so bad clickbait title 👍

You could also use 6 wheels like the Tyrrell P34, March 240 Or even 8 wheels for both sides

You should test this in a gym or any place with polished concrete. Additionally, the skirt could probably be made out of overlapping flexible "tongues" that angle backwards and can bend when pressed down. Combat robots often use this as a flexible wheel system that's difficult to damage.

I have been watching KZfaq since it began . This is the ABSOLUTE BEST video EVER. Thank you SIR! Society needs you to be a teacher. The education system in every country needs to hire you as an online mandatory teaching lesson.

Imagine someone was just casually walking on the side of the road and then he hear a sound but he doesn't know what it exactly is and after he go around the corner, a fast tiny car suddenly goes right pass him, he stand there in awe but not even 5 seconds later he feels a sting on his right foot when he looked down, his right foot is gone.

12:19 And that's exactly why this was banned in F1 a couple of years later. Awesome recreation, really amazing they were brave enough to try this in manned vehicles.

I'm about 1 minute into the video I had always wondered why no one has tried to do this with an RC car 👏👍😁. I'm already loving the video 🤤

Imagine the ideal track. When you make the care smaller, everything else gets bigger. If everything was smooth, flat, and sticky, I'd love to see an rc car race of practically mini f1.

A softer skirt, like one printed from TPU or made of rubber, might help. Something that can take the impact and deform to the shape of the road, rather than bouncing the car off the wheels. Also, i beg of you, if you're already going down this path, consider adding a second set of steering wheels at the front like the famous Tyrell P34 :P It might genuinely help with cornering.

Hi, I personally loved your F1 RC car project, so I'd like to give you some ideas: maybe you can add some sort of plank, like actual F1 Cars, to reduce the minimum distance from the ground of car's floor to avoid skirts damaging and maybe try some TPU 3D printed skirts to improve the vacuum effect. Have a good day!

For the skirt you could try some flexible rubber like a hovercraft, or perhaps some brush material like a paint brush. Try soft or hard bristles and see if there's a difference. I imagine you want something soft enough to adjust to the road surface without losing too much air pressure, although losing some air pressure might be preferable to losing traction on the tyres.

I would recommend attaching the skirts to the suspension so that it moves with the suspension rather than the chassis, but this is really sweet!

engineering helper.. _put a ring on it james_

11:52 are we just not gonna talk about how clean off a drift that was

The trick is to mount the large alloy plate & edges off the bottom of the suspension uprights and not the chassis, so its height above the ground doesn't change.

i'm an f1 nut and i know back in the day they had a semi rigid skirt that would bounce inside a receiver style channel, i wonder if you could construct something like that and try t again. despite the porpoising as soon as that fan cut off it was going straight to the scene of the accident, awesome look, need a 2.0 video

The rubber from a bike wheel tube might be good for the skirt since it's flexible and coulsd run along the ground without much damage.

Another thing that would be interesting to try would be to just put some drone motors with reversed props on top of the car. No need to worry about a seal and it woukd even work well off road.

The F1 skirts they used were free floating or spring loaded - gravity/spring force meant that they were always sealing to the ground but without bottoming out the car or bouncing

It might be complicated, but the chaparral's fan car had the skirts somehow linked to the suspension so it stays in the right attitude, might help you with the consistency around the corners. There are so many details about those fan cars and active aero in general, have fun going down that rabbit hole!

That's the best road I've seen in years, it's basically potholes in Plymouth. 😂

After watching up to 13 minutes on this amazing video I recon the low pressure false floor should be connected to the wheel carriers instead of the chassis. That would allow a softer and grippier tune of the suspension and still maintain the seal to the ground, maybe? Williams used something like that in F1 in the early 80's.

When I saw this the only thing I could think of was Delrin. Strong with low friction. Combined with a spring (maybe like an apex seal spring from a rotary engine) would help to keep the skirt in contact with the ground. Low friction with increased longevity.

4:19 3D printed fractal support trees 🌲🌲

@Project-Air Get some door sweeps, They're just brushes on rails for the base of doors. but they will maintain a more reliable seal without bottoming out

Might want to try brushes next time on the skirt. Use them for weatherstripping and they are way more sealed than you'd think they could be considering they are just bristles. The way they conform to the rough surface more than makes up for the losses between bristles.

Although this might be hard to accomplish, but there was a design on the chaparral 2j regarding the side skirts. The 2j was a fan car, but had issues with maintaining proper suction. The car had a mechanism where the skirts would move up and down as it was linked to the suspension, preventing it from scraping against the track surface

8:58 You were right the first time around. That, my friend, is a ship, not a boat. When it turns it leans to the outside. Boats lean into the curve.

With Can AM cars the skirt height was controlled by the suspension via cables and rockers. This allowed the suspension to do its job while maintaining the necessary skirt clearance.

Very nice project! Congrats! Next step you can try to seal the bottom with 3mm thick rubber and test it on a smooth surface like a flat parking area... I'm shure you will have great results..

The skirts on F1 cars were moveable pieces slotted into the sides which would allow for the sealing over bumps. I'd love to see you build more on this idea, maybe trying more skirt materials, or even changing the fan duct shape.

Your skirt seal needs to be a large flat area PARALLEL to the ground. Make the air work to travel a large horizontal distance to get into the vacuum. The pressure will suck the skirt down too.

my guess: since you have independent suspension, make a 4 part skirt with a flexible cross, so wheels can still independently move, and the skirt gets closer to the road.

I use horizontal uhmwpe strips fastened with 3M VHB double sided tape stuck to 90 degrees carbon strips, to seal the floor to the ground on my race car. We don't have electric fans, so have to rely on the low pressure generated by the floor/diffuser to pull the car down to seal against the track, which only works above 60mph. The uhmwpe strips are low friction, and easily replaced once they're worn down.

Plywood skirt might work better with halved garden hose mounted over it to act like a proper seal and absorb the bumps, mimicking an actual skirt.

Great project again! This is exactly my thought for pushing the next level of the RC car speed challenges. Down force with little drag penalty. Also hub motors to remove the drive train issues and be able to use gyro stabilised DTC to keep it straight. Tyres are the only unanswered question.

9:31 that's gotta be one of the smoothest add transitions I've ever seen :lmao: Edit: Also, I'm just thinking back to the Chaparrel 2J, a car by I think the same engineer (?) as that F1 car, and the skirt was linked to the suspension on that car, so whenever the car cornered the skirt actually moved (but that's *probably* too mechanically complex for a small RC car like this)

Bigger fan with more flow to compensate for leaky skirt. Skirt that is attached to swingarms so it stays fixed relative to the wheels when suspension moves.

you should try a lifting (venturi) underbody with the front end open. you'll probably get less downforce but it won't be so dependent on the sealing

Ay the car has returned!

when i first heard about this formula 1 car i had some ideas of my own but testing them on a life size car was never going to be in my price range so you have given me a good idea, thanks

I think the 10-bladed fan would work better in a live test: more air escaping under the skirt = more airflow = more cooling for the motor.

From the beginning, looking at your preview videos, I could see that the cornering test was going to be flawed because of the rocks and the uneven surface. It would be cool to see you try this again on a track surface that is smoother and figuring out the perfect ride height. Good job on the video

The skirt should be make out of those brushes they use to seal gaps under doors. Basically a long toothbrush.

Just some ideas that could improve speeds: - Smoother track (Obviously) - Replace the metal sheet with a custom lightweight fibreglass one - Make the steering linkages to the front wheels stronger as they where wobbling a bunch causing the car to become unstable - Make the skirt out of fibreglass or some type of material that can bend in the traveling direction to reduce the amount of damage - Change tires now and then - Different motor for the fan that can output a bit more power to allow for the 10 blade design without overheating - Think of a new front end design for the skirt, different design that having them sloped at a 45 degree angle could improve handling (Basically like toe) and maybe reduce damage - Put spacers on the rear wheels as they look to be lightly rubbing on the rear fins/wings. You can kind of see it at 16:20 - RGB strips for 0 - 60 in 2 sec

Really should have started from propeller design if you're going to build fan assemblies from a selection of options. Having a lower RPM higher torque motor (different KV rating to prevent heat loading via efficiency loss, which is why the 10 blade fan made the motor draw power beyond what it can handle heat wise, but made more vacuum) helps you run propeller designs more optimized for efficiently creating static pressure, so you'll get more pressure difference for a given electrical output. PC fans and boat propellers both take static pressure vs. air volume into consideration. Material for the skirts must have a low elastic deformation force, with a high elasticity limit to account for all the rocks and road debris. Making it as thin as possible without distortion also helps. Or, keep the foam and run it indoors on a clean surface.

Remember that rc cars are still downscaled. Driving on a normal asphalt road would scale up to like a cobblestone like surface. Perhaps a soft, flexible rubber profile could be worth a try. Quite cheap and more durable than the foam. Also, it could dampen bouncing.

when the F1 engineers were trying to make the fan cars work the best material they found for the skirt s was aluminum or Lexan . they even tried using brushes but they where a lot heavier then the other option . the chaparral 2J was the fastest with it's floating skirt that worked with arms connected to the suspension to keep the skirt tight to the road. but trying to make this work on a model car would be a nightmare .

If you can somehow able to attach the skirts to the wheelhubs. Make it part of the unsprung system. This would allow the skirt's ground clearance to be more consistent.

Wear some cut resistant gloves, fingers are important! Try those under-door rubber sweeper things that are designed to keep bugs out, warm air in.

Next time, consider using a leaf blower to clean the road first :D. Awesome video

Chaparal 2j used a pretty cool mechanism in order for the skirts to always be at a set distance from the ground.

I liked your DIY KZfaq manometer 🤣😃

Great video yet again 😃 The original F1 cars used thick rubber to seal the edges, but they used springs so they could move a bit through the undulating surfaces. Might be worth looking into 😊

What about a skirt out of rubber? That would be more flexibel and maybe more durable than one of foam board. Keep up your great projects!

The rubber "blades" from a window wiper would be perfect for your needs for the skirt

Maybe try something like the 2J. Tie the skirts into the suspension. Allows you to still have suspension, as well as more consistent seal

Could you imagine racing behind someone, when the person in front of you starts sucking up debris and launching right at you. It would be like Mario kart.

You should take a look a the Chaparrall 2J, which was the first fan car. Jim Hall has a sort of interview/video where he showcases all the cars he designed and has extra info on the 2J and how it works.