RC Hypercar Pt4 - Extreme Aerodynamics

This is part 1 of the RC Hyper car aerodynamic development videos.
If you’re looking for an easy to use CFD service, checkout AirShaper:
airshaper.com/
You can also checkout the CFD results on AirShaper's website for yourself:
app.airshaper.com/projects/rc...
Link to Joseph Katz research paper on VG's used for underfloors:
www.researchgate.net/publicat...
Link to Kyle.Engineers KZbin on aerodynamics
/ @kyleengineers
Lecture by Willem Toet on aerodynamics
• Masterclass with Wille...
#rc #3dprinting #motorsport

[@bytesandbikes]

That looks so stable and balanced given the relative surface quality!

[@IndeterminateDesign]

Yeah, it's very stable at speed and you can't really spin the car out. It's hard to describe just how fast the car turns.

[@EngineeringAfterHours]

Awesome! Looks like what would happened if you took a valkyrie and made it a time attack car.

[@IndeterminateDesign]

Thanks. Adrian Newey knew what he was doing.

[@alesksander]

@@IndeterminateDesign Yeah maybe he knows thing or two haha

[@alexbrown9822]

Excellent video thank you, very much look forward to the next one

[@1993ka24det]

I like the front fenders, the front half is like what I'm building for my Exocet.

[@IndeterminateDesign]

Nice. I’ve always thought an Exocet would be the perfect base for a custom body.

[@nickg00]

Great video. Keep it up

[@IndeterminateDesign]

Thanks, will do!

[@juanmedinar20]

Subscribed. Awesome channel.

[@toolscientist]

Great stuff. I know it'll add to your edit time, but can you add some callouts (text and arrows) to sync with your voiceover. I'm familiar with aero, but not racecar aero, so it often took me a while to figure out what I should be looking at when you were talking about the throat or vortex generators and diffuser. Switching between the CFD images and physical car would also be useful as it's easier to see the 3-dimensionality of the real car compared to the renderings.

[@IndeterminateDesign]

Thanks. I love your suggestion. Seeing all the features in 3D is so hard. I’ll integrate filming the actual car. Engineering I get. Story telling and visualization of the engineering is so much harder.

[@beachboardfan9544]

25:45 Heave spring suspension!

[@RoadToad42]

So I've seen two fundamental strategies to underbody stuff. 1) High/Open nose, force more mass flow rate under the car to make the tunnels work. 2) Blocked/Low Nose (like a splitter/air-dam) - Prevent air going under to make a low pressure suction area behind the blocked part. I assume in general, option #1 is preferred if rules allow wacky floor antics?

[@IndeterminateDesign]

I think #1 can make the most downforce, but probably has more drag. I tried both high and low nose. Even an inverted nose like FSAE cars. This car is kind of a mess because RC car suspension components are so oversized for the scale. Luckily the front wing on this car is really high up for ground clearance and that lets a lot of air pass underneath.

[@torstonvodesil6709]

This is so cool. Is the extreme force on the tyres wearing them out significantly faster? Do you plan to change or upgrade the tyres for this project? Can’t wait for the next video 😁

[@IndeterminateDesign]

Thanks! The tires are a real issue. I actually wear through the edges because they roll over so much. I’m testing custom tire inserts but I also have some suspension issues to work out. That’s the fun of a project like this. There’s always a new problem to solve.

[@StevePringle]

Does it come in black? I need one to go spelunking. 😅

[@Casey_Schmidt]

That is an impressive result! I’m not sure if it would even matter at this scale, but would reducing interference drag make any improvements? Interference drag is caused by adjacent surfaces that meet at right/sharp angles.

[@IndeterminateDesign]

It would definitely make a difference. I need to smooth more of the surfaces and honestly just sanding and painting the car would have a big effect.

[@Casey_Schmidt]

@@IndeterminateDesign considering that reducing weight is more important than drag, is light-weight PLA and option for any parts on the car? I know it’s not an ideal material structurally but I know a lot of the modal aircraft guys are having a lot of success with it.

[@IndeterminateDesign]

I just bought a roll of lightweight PLA last week to try out. I think the light weight PLA is good for the rear wing. It could work for the monocoque, but I’m worried 1 crash and it would be done. So I got some ASA for that.

[@GatorGlider]

My printer is itching to spit out this thing! Are you looking for real-world feedback? I'd also love to build some molds and make the body out of a carbon fiber layup.

[@IndeterminateDesign]

I'm glad you like it. I'm probably several iterations away from wider spread testing. I'll delve into this in later videos, but the car has a long list of issues that will require a redesign of the monocoque and the suspension. I'd love to see how this car would perform if built entirely from carbon fiber. I can only imagine the number of molds that would be needed, considering the complexity of the monocoque and all of it's integrated mounting points.

[@Liberty.Francis]

I had done lots of reading and best I could tell we needed 60mm ground clearance to not have issues with boundary layers stalling the airflow near the ground. It appears my numbers were wrong! I keep thinking of making a scale wind tunnel with treadmill. I don't want to pay for simulations 😆

[@IndeterminateDesign]

That’s interesting about the boundary layers, I think that has to be for a particular application. I can tell from the dust patterns on the diffuser the flow stays attached. The real key is have a lot of high energy air flowing under the car. The giant rear wing and the vortex generators help. Obviously this is not a low drag application. This car at 60mph has double the drag and double the downforce of the streamliner at 200mph.

[@Liberty.Francis]

@@IndeterminateDesign That's awesome. I was working on a car that looks like a catamaran with 150mm diameter tires to help give a large air gap under the car. It seems like I could reduce that air gap significantly. The large diameter still may be a good thing for tire longevity at high speeds

[@IndeterminateDesign]

That’s awesome. Kind of like the old Adam’s Escort Can-Am car? Honestly that’s the way to go. I’ve designed one last version of the Streamliner but without the traction 200mph will take over a mile. A 150mm wheel is huge. There has to be a better solution for high speed tires.

[@Liberty.Francis]

@@IndeterminateDesign yeah and fan cars (sucker cars) are cool. The 1/8 foams have a 90% failure rate above 190 mph

[@fastslash25]

are you still running no torque vectoring? any gyro or similar?

[@IndeterminateDesign]

No torque vectoring right now. I do have a gyro/accelerometer onboard that I tried using using for stability, but I usually just keep it turned off. The gyro interferes too much at high speed.

[@fastslash25]

@@IndeterminateDesign ah alright good to know, was curious because I'm using hub motors for efficiency hopefully but wasn't sure if it just wasn't stable or my surface was just really slippery. its a 1/10 carpet pan car running on hydrogen

[@IndeterminateDesign]

@@fastslash25 That's awesome. Are you using a fuel cell then? The hub motors are very touchy at low speeds, I run 50% expo on this car right now. I'm running the motors in sensorless mode on the ESC and I can tell there is a slight difference in torque between the two motors at low speeds which can cause instability. I'm hoping to add hall sensors to the motors and this should keep them in sync better.

[@fastslash25]

@@IndeterminateDesign yea currently using 2x of hydrogen horizons 30w pem fuel cells on the current competition car. Hub motor car is not on hydrogen at the moment. I was worried the slight torque difference could be a problem, I was thinking of trying some hall sensors too. I think you're going to hook them up to the esc somehow though right? I only am familiar with maybe changing the pwm according to hall sensor readings. Is it possible to use a sensored car esc with one of these outrunners?

[@IndeterminateDesign]

@@fastslash25 The torque difference would probably be very minimal with the output you're looking at. I have tried adding hall sensors externally to my outrunners, it works technically but it needs more perfecting. Here's a clip of my setup from IG instagram.com/reel/Cnix5X-O2WB/?igshid=MzRlODBiNWFlZA==

[@FirstLast-tx3yj]

Some similarities with the valkyrie amr pro only turned up to 9000

[@IndeterminateDesign]

Yeah, I took a lot of inspiration from that car and the Praga R1.

[@FirstLast-tx3yj]

@@IndeterminateDesign would it be useful just as an idead to channel the air from the front wing outwash with tubes on the left and right towards the rear above the diffuser just like in the fwd nissan gtr lmp1 car?

[@IndeterminateDesign]

I did play with that and I couldn’t get it to work. The diffuser is so much bigger than a normal race car, that it’s almost at the top of the rear bodywork. That’s why the gurney is so big on the tail of the body vs on the diffuser. I get a lot of fresh air feeding right over the top of the body. I’m getting a lot of strange effects back there, the rear wing is backed off in the middle too and for some reason that makes more downforce on the floor. 🤷‍♂️ It’s so hard to find a comparable in a real life car for this thing.

[@Firashelou]

amazing work ! you are a pure engineer very talented ! please check your email, i have sent you an email the other day

[@IndeterminateDesign]

I just sent you a link to the github where I have the project. May not always be a stable release as it's a work in progress.

[@IndeterminateDesign]

I just sent you a link to the github where I have the project. May not always be a stable release as it's a work in progress.