Battery Buggy B

[shrewdPanther46]

If you have skid and curvature, you should really try to fix it instead of just accepting it and accounting for it. In both my years in EV, I have known the top 3-4 medalists at nationals and NONE of them were accounting for skid or curvature and everyone was using linear regressions of some sort to determine distance (and steering angle for 2017, although Harriton's system was a bit more complex in that regard).

We have managed to get rid of basically skid altogether by braking earlier (well atleast we can't see any skid visually or in a blown up video). Our car still fishtails annoyingly towards the end of our runs to the right, and depending on the floor, it is usually between 8-10cm. We have been simply "accounting" for it as you said by angling it 10 cm to the left, and it is pretty consistent on the same floor with good effort for angling (<4 cm from the line usually).

We have tried playing with weight distribution, total car mass, braking speed, braking methods, starting voltage, and as many factors as we could think of, but we were never able to get the car to stop fishtailing so now we are sitting with what we have. Any suggestions regarding how to approach the issue and if it is ok to stick with it? In terms of total distance, we are able to get <5 cm every time on the second run, and we are working it down with alignment practice (i know that sounds kind of dumb, but we aren't using a rifle scope, so it is kinda difficult to align it properly and we need a lot of practice with it). We are also planning on making a regression for alignment distance from the tape over distances. We are also keeping voltage the same so centripetal forces are acting consistently on the wheels particularly during the fishtailing process. Thoughts?

Thanks!

What kind of wheels are you using? It sounds like friction force isnt equally distributed either due to poor traction or poorly distributed center of mass. Fish-tailing is usually the result of an underlying oversteer phenomenon https://en.wikipedia.org/wiki/Understeer_and_oversteer. Also what is the mass of your device currently?

Balloons or any kind of tire should eliminate skid
or it might just be a problem with your braking system

If you have a competitive device going at high speeds (<2.5 seconds), balloons are not nearly sufficient in providing traction,.

I am using banebots, and I highly doubt that the issue is due to poor distribution of mass because our car is theoretically symmetrical along its central axis. The mass of our car is around 1.2 kg.

[MadCow2357]

I would advise just buying the long sticks and cutting them down with a hacksaw or bandsaw

Yes do this, except use a rotary tool like a Dremel or something similar so you dont damage the CF

I want to go with the F1 this time, as the coolness factor, in my opinion, is way above the rectangular frame

This is NOT a good reason to go with this design lol
The correct reasons are as follows:
Benefits: Elimination of chassis torsion and it allows for implementation of passive adjustable steering (as seen on EV 2016)
Cons: Difficult to implement correctly - fit between CF and 3D printed parts MUST be an interference fit or you WILL run into problems (you cant just glue/epoxy the rods in - the fit needs to be so tight that you have to lube the rods and hammer them in.
These pros/cons are not self-evident and i didnt realize them until I struggled with chassis torsion on my 2017 EV which required a complicated solution to solve.

3. Can I drill into carbon fiber and ABS?

You can, but don't unless you have precision rotary tools (Dremel) and steady hands. Design your parts in CAD with whatever holes are needed.

So, can I use my mini hacksaw? I don't have a dremel. But how would something damage the CF?

Yeah, the idea came from your 2016 EV and how cool it looked, but I am also going for the F1 design because of weight reduction. I will 3D all of my parts, except for the CF. I made 8mm square holes that are 1cm deep on the connecting pieces. Will that work?

[shrewdPanther46]

The CF fibers will get messed up... its like cutting balsa with a dull blade

[MadCow2357]

The CF fibers will get messed up... its like cutting balsa with a dull blade

Ahh... I see... I'll try it anyway, but I will try something else if it doesn't work.

[hippo9]

You can try, but if it doesn't work just redesign and print using CAD(assuming you have access to a 3D printer).

[MadCow2357]

You can try, but if it doesn't work just redesign and print using CAD(assuming you have access to a 3D printer).

The cf parts? I am already using 3D printed connectors.

[shrewdPanther46]

He is saying u can trial and error your way to the appropriate size for a press fit.

[hippo9]

He is saying u can trial and error your way to the appropriate size for a press fit.

Yeah, and I don't know if your does this, but I've seen 3D printers that can print carbon fiber.

[shrewdPanther46]

Its actually CF filament.. so u can theoretically make your chassis out of completely carbon fiber
EDIT: we looked into it, didn't want it for the price given that you need a separate nozzle too. My partner just printed it in PLA (green for the memes)

[MadCow2357]

But normal 3d printers can't print cf. I'll see if I can borrow my math teacher's Dremel to cut my CF.