Mousetrap Vehicle C

[antoine_ego]

So I'm essentially done with a rough prototype of my vehicle which I made without too much thought going into its weight. I plan to redesign and/or modify in order to cut down on the total mass as it feels fairly sluggish right now and I'm unable to increase drive axle size without running out of string. Can someone provide me with a rough estimate of how much a decent car would weigh so I can know what to shoot for?

My current vehicle is sitting at around 350g and is constructed in part from balsa, although most of the weight is coming from the metal wing-nut stopping system and from Lego pieces which I used for part of the frame. Do people have recommendations for materials or construction methods which would minimize weight while not sacrificing too much strength? I, unfortunately, don't have access to a 3d printer.

Thanks!

I'd say a decent car would be about 250g, which is definitely feasible. Have you tried using a plastic wingnut stopping system? The issue with this is that you sacrifice some rigidity in the system. For the frame, you can always try carbon fiber, which is more than strong enough to handle the forces.

[windu34]

alrighty, thanks! what is a good grip for wheels? I have CDs right now. I think balloons should do something for right now until i figure out a better solution?

I've used CDs in all the other vehicle events (Wheeled Vehicle, Scrambler, EV) and they've worked very well- some skid is bound to happen . The only other thing I'd consider would be those Banebots robot wheels (or similar), though CDs might still be better since they weigh less.

I would look into the 0.4 in banebot wheels and drilling out parts of the plastic to reduce inertia

[4Head]

alrighty, thanks! what is a good grip for wheels? I have CDs right now. I think balloons should do something for right now until i figure out a better solution?

I've used CDs in all the other vehicle events (Wheeled Vehicle, Scrambler, EV) and they've worked very well- some skid is bound to happen . The only other thing I'd consider would be those Banebots robot wheels (or similar), though CDs might still be better since they weigh less.

I would look into the 0.4 in banebot wheels and drilling out parts of the plastic to reduce inertia

I think foam wheels would be best for lightness. You can increase the grip with balloons or tape and it probably would be quite a bit lighter than even a drilled out banebots wheel (which would end up around 30 grams still).

[RJohnson]

I would look into the 0.4 in banebot wheels and drilling out parts of the plastic to reduce inertia

I think foam wheels would be best for lightness. You can increase the grip with balloons or tape and it probably would be quite a bit lighter than even a drilled out banebots wheel (which would end up around 30 grams still).

30 grams for one wheel or for the set? According to their website, each 2-3/8in wheel weighs approximately .62 oz (17.6 g). With some skillful drilling you could probably get it down to 12 g or so, maybe even better. Not entirely sure of the relative density of the plastic vs. the rubber. Use a 1-3/8 wheel and you start at 7.1 grams... I'm not ruling the banebot wheels out yet.

[4Head]

I would look into the 0.4 in banebot wheels and drilling out parts of the plastic to reduce inertia

I think foam wheels would be best for lightness. You can increase the grip with balloons or tape and it probably would be quite a bit lighter than even a drilled out banebots wheel (which would end up around 30 grams still).

30 grams for one wheel or for the set? According to their website, each 2-3/8in wheel weighs approximately .62 oz (17.6 g). With some skillful drilling you could probably get it down to 12 g or so, maybe even better. Not entirely sure of the relative density of the plastic vs. the rubber. Use a 1-3/8 wheel and you start at 7.1 grams... I'm not ruling the banebot wheels out yet.

I did it by the 2 7/8 wheels, which are .85 oz iirc

[windu34]

I've used CDs in all the other vehicle events (Wheeled Vehicle, Scrambler, EV) and they've worked very well- some skid is bound to happen . The only other thing I'd consider would be those Banebots robot wheels (or similar), though CDs might still be better since they weigh less.

I would look into the 0.4 in banebot wheels and drilling out parts of the plastic to reduce inertia

I think foam wheels would be best for lightness. You can increase the grip with balloons or tape and it probably would be quite a bit lighter than even a drilled out banebots wheel (which would end up around 30 grams still).

Not a fan of using balloons for grip. While a good low-end option and very cheap, if you are looking to get a high level of performance out of the vehicle, I would not recommend that. The few extra grams will be worth it. Tape sounds inconsistent.

[4Head]

I would look into the 0.4 in banebot wheels and drilling out parts of the plastic to reduce inertia

I think foam wheels would be best for lightness. You can increase the grip with balloons or tape and it probably would be quite a bit lighter than even a drilled out banebots wheel (which would end up around 30 grams still).

Not a fan of using balloons for grip. While a good low-end option and very cheap, if you are looking to get a high level of performance out of the vehicle, I would not recommend that. The few extra grams will be worth it. Tape sounds inconsistent.

that makes sense. A few grams is quite negligible and I get your point about grip.

[dragonfruit35]

I think foam wheels would be best for lightness. You can increase the grip with balloons or tape and it probably would be quite a bit lighter than even a drilled out banebots wheel (which would end up around 30 grams still).

Not a fan of using balloons for grip. While a good low-end option and very cheap, if you are looking to get a high level of performance out of the vehicle, I would not recommend that. The few extra grams will be worth it. Tape sounds inconsistent.

that makes sense. A few grams is quite negligible and I get your point about grip.

Yeah, CDs have the same problem with the balloons- they wear out after a few uses and tend to cause skidding. I'd think you might want to either invest in some "fancier" wheels or try to come up with an alternative tire (for either CD or foam wheels).

[antoine_ego]

Let's get this thread rolling again... What sized axles are people using? I've been using 1/4in, but I'm considering moving down to save weight. Also, has anyone found light threaded rods that don't bend a lot?

[markuswso17]

Let's get this thread rolling again... What sized axles are people using? I've been using 1/4in, but I'm considering moving down to save weight. Also, has anyone found light threaded rods that don't bend a lot?

I like to use 1/4" carbon fiber rods. They are incredibly light and strong.