RC Hypercar V2 - Failure is an Option!

[@costin4985]

Trust me, those engineering cuts are not boring or less exciting!!! Your video on Traction Control motivated me to approach the same subject for a uni project. Now on my diploma project I also want to work with RC cars involving Autonomous Racing. I'm glad channels like yours where you also put effort into explaining the engineering behind such projects exist.

[@IndeterminateDesign]

That's awesome! I'm glad you enjoy this. I actually can't wait to get to the part where this car is reliable enough for me to try out traction control and torque vectoring. I'm planning on having encoders on each wheel, so I should be able to do some cool stuff.

[@occrc3333]

I have been designing a car for a while and I have no engineering background. Your videos really help me understand how different components affect the car. Thank you and good luck with V3

[@IndeterminateDesign]

Thanks. I'm glad this helped you. I definitely feel like I've learned more than I ever wanted to know about suspensions with this project :-).

[@c9ollie]

Its interesting to see just how rough the surface is at this scale. At full scale it would be like a F1 car driving down a gravel rally stage. Super interesting. It would be cool to see the car at a mega smooth RC road course.

[@IndeterminateDesign]

Yeah, the surface is extremely rough. I'd love to find a giant newly paved asphalt parking lot, or an abandoned factory with smooth floors.

[@nickrudd2568]

Ive been using Esun PLA ST recently, Very tough stuff, not had anything break so far and no print fails.

[@cari187]

Eager to see the data your custom pcb will allow you to collect! Hope we see the 3.0 chassis soon! :D

[@IndeterminateDesign]

I'm eager to see as well. I think there's a lot of cool data to be pulled from this car. I've been obsessing over the design trying to get it perfect.

[@loopie007]

I cannot wait to get the sensor data from the car. This is something I had hoped for many years ago. I would race 1/12 scale indoors, but it was impossible to get feedback on what was really happening. With true sensor data, it was just following superstitions and whatever the factory guys did. Motors, gearing, tires, etc. All guessing, all the time.

[@IndeterminateDesign]

I’m excited for the data too. It’s crazy how much money is spent on RC race cars and they don’t have data. I know when I used to race full size cars, data was everything because so many times the car would feel better and end up being slower. I honestly think a lot could be done aerodynamically with pan cars. I be it would be banned, but that’s the perfect surface for that.

[@Anselm1115]

Im not too deep into suspension design, but i believe the high amount of tire wear on the outsides of each tire might resulted from a camber-travel-curve, which isnt ideal for cornering. basically when the car rolls in the corner, the outside suspension compresses and the inside compression extends. in that situation, it can occur that the area of contact between the tires and the road decreases, because there is an angle between them. therefore the outsides/insides of the tires would undergo more degredation. the camber-travel-curve should be tuned, to maximize the contact of the tire patch in that situation. Maybe you already thought of that. ive built a rc car myself and that was a major flaw. Anyway your project is super interesting!! keep it up :)

[@IndeterminateDesign]

I feel like I don't know enough about camber tuning myself. I think it really does require a test rig so you can see how the tire is deforming. The major challenge with this car is the load on the tire. A typical RC touring car has about 300-350g of weight per tire, but at top speed this car at speed has ~1.3kg. My theory is the side walls of the tire just collapse.

[@torstonvodesil6709]

There are a couple “variable density” foaming TPU filaments out there that might help you with the tire stiffness problem. They’re very expensive but it’s some of the softest TPU on the market. Engineering cuts are great!, I would love to see a tire test rig if you find the time to work on it.

[@IndeterminateDesign]

Thanks. I’ll check those out. I was just given a supplier of various densities of tire foam so I’m going to try them out. I’m glad you enjoy the engineering cuts. I’m really surprised there isn’t tire testing and data available for RC car tires. Seems like a big area that could improve performance.

[@toolscientist]

Amazing work, as always. Loved the leaf blower test. Are you still considering unsprung aero for the front wing or is it too hard to package at this scale?

[@IndeterminateDesign]

The leaf blower works really well as long as you keep it far enough away. I really do want to try to do a something with unsprung aero, but I don't think I can fit it in this car. I also didn't position the suspension rockers in the best orientation for this. Maybe someday I can do an open wheeled variant of the Hypercar where I have more room. The rear wing is the only aero device that really lends itself to being able to do this, and it's ~1/3 the car's downforce.

[@rccrazer]

I like engineering cuts

[@nestoNESTOnesto]

Wait what do you mean "Tamiya offers" Screw Tamiya, get a racing tires, not barely better than toy tires that Tamiya is making. You need belted racing slicks from Sweep, Ride or LRP.

[@IndeterminateDesign]

Awesome! Thank you. I'm going to check all of these out. I've had a hard time finding what people are racing with and most of the ones I do find are all pre-glued.

[@nestoNESTOnesto]

@@IndeterminateDesign But one warning. Racing tires are 24 wide instead of 26. It may need some design changes because of it. But you can choose hardness and that mean ideal temperature. I must recommend Sweep specifically. I'm making 1:8 prototype somehow similar to yours and they were so kind to sell me those tires without pre-glued wheels. For some reason 1:8 are not normally sold separatelly.

[@bytesandbikes]

I wonder if you can make 3 part wheels and clamp the tyre sidewalls? Maybe with an inner lip to reduce turn-over

[@IndeterminateDesign]

I haven't tried that. I'm concerned the bead of the RC car tire is just too soft because it doesn't have any reinforcement internally. I did change the rim design early on to match an RC car touring rim where it comes up higher so that rim can be glued better to the tire. The hard part is the tire itself is being torn and a layer of rubber is still attached to the rim.

[@bytesandbikes]

@@IndeterminateDesign That's an interesting thougt. Maybe add a thin layer of reinforcement to the tyre, or cast tyres in polyurethane with fine glass or carbon toe. Probably just adds another layer of complexity! 😵

[@chris993361]

Instead of tpu, and I can't remember what it is called, but there is a pla that foams based on temperature that may allow you to tune stiffness.

[@IndeterminateDesign]

Yes, there's a light weight PLA that foams. I've thought about that but I don't know how flexible it is. I may make my own 3d printed machine to shape my own higher density foam.

[@chris993361]

@@IndeterminateDesign fair enough.

[@king_br0k]

Would be hilarious to enter this in a combat robotics mtch and drive circles around everyone

[@IndeterminateDesign]

Yeah, nothing would be able to keep up with it for sure. It would be hard to keep from crashing though. It seems to do that well.

[@king_br0k]

@@IndeterminateDesign how heavy is it currently?

[@IndeterminateDesign]

@@king_br0k 1.7kg

[@johnnycomelately6341]

Were the tyre sizes (width) calculated for the aero loads and car weight?

[@IndeterminateDesign]

The tires are 28mm width. If I could find wider tires in the same diameter I'd definitely run those. The car is 1.7kg, and the suspension is setup for up to 5.5kg of downforce (CFD says 8.1kg at 60mph, but I think that's a bit high). So about 1.3kg per wheel, which is several times what the typical RC car tire has.

[@johnnycomelately6341]

OK, thank you @@IndeterminateDesign

[@GatorGlider]

When are models going to be available for printing?! I'd like to try to do the body in CF nylon.

[@IndeterminateDesign]

I don't know if the video's convey just how rough the design is still and how much hand finishing of all the parts is still required. The car is made from 3 different materials, almost every part has it's own unique print settings. I have a 2 page long list of notes just for setting up the slicer and prepping to print the monocoque (Even with this I still had 3 print failures on the monocoque in the last two days with PLA). My hope was to get the suspension and body at least to a point where it wasn't changing radically, create a bill of materials, and then film a rough 1-2hr long video on just printing and building up a chassis. I feel like I could save people a lot of time, and maybe we can setup a wiki or blog keep an ongoing set of documentation. Also, once the design is stable there's a lot of little tweaks that can be done to make things so much easier to 3D print.

[@GatorGlider]

@@IndeterminateDesign I hear you 100%. It's hard to convey via comments (and I'm not good at it) but there is a lot of enthusiasm and desire to help out. I think having certain parts out there for a beta type audience to test printing might give some good feedback. For instance, I've gotten pretty good at printing CF nylon which I have found works great for 3d printed cars. It might not be robust enough to take a curb at 60mph, but I found its ability to stave off the cracking that I get in single wall PLA to be beneficial. Do you have a Discord or some other forum for discussion? I'd love to discuss solutions to making this printable.

[@juanmedinar20]

What 3D printer are you using? Maybe try to use formula 1 RC belted tires. Exotekracing makes a bunch of different compounds with their corresponding tire foams and they also make firmer foam insert for drag tires. They probably can help you out if you call them, IIRC they are the only approved class tire for F1 in the USA for this year. The project looks great.

[@IndeterminateDesign]

I’ll check out those F1 tires. The hardest part is finding the diameters of all these tires because they’re all size by the type of car not by the actual measurements 😂 The printer is an Ender 3, but the only original part is the frame.

[@juanmedinar20]

@@IndeterminateDesign why are your body models hard to 3d print? I designed and printed some GT12 RC bodies and F1 bodies and I have no issues with my Bambu Lab 3D printer. The Bambu Lab printer is the best purchase I have made in the last two years; it is just fantastic. Maybe share the body models with me and I can print them out just to see if they pose issues.

[@IndeterminateDesign]

There are two main challenges with this car. First, there are parts that eventually merge into the monocoque, that are only 1-2 walls thick, 0.4 -0.8mm. These parts vary between 5-25mm tall, being printed on top of nearly 75mm of support. They can be broke off by the extruder very easily, and prone to warping because they cool so fast. The other challenge is the body has multiple shells, the monocoque and the body itself. These shells don't have great access for the supports to generate. The supports have to go from 5mm or less at their base, grow up 150mm through a narrow channel between the shells, and then support something 30mm wide that would be printed in midair otherwise. (Basically like trying to grow a tree upside down). So currently, it involves lots of manual support blocking and placement of custom designed supports that have to be cut out later. Sometimes I don't get it right, and the supports aren't strong enough and get broken and then the print fails. It's all fixable things, but printability hasn't been my priority to the point. Honestly this complex shape is probably best printed by an SLS printer so that no supports are needed.