Battery Buggy B

[fleet130]

Some Ideas. There are probably many other causes.

Sideways skid is usually caused by a difference from one side of the vehicle to the other. Some causes are: difference in traction of the tires, difference in braking, different wheel diameter and/or difference in weight distribution.The cause can be difficult to discover. Watch closely as the vehicle skids to a stop. I can remember an instance that took a couple of hundred runs to figure it out. In that case, it was something rubbing against one tire momentarily as the brakes were applied.

If it happens as the vehicle runs down the track, it is probably associated by "wheel hop". I observed this many years ago with mousetrap vehicle when speed was a factor. The vehicles were made as light as possible so they could accelerate faster. Small imperfections and dirt on the track could cause the vehicle wheels to hop and change direction dramatically.

[new horizon]

Some Ideas. There are probably many other causes.

Sideways skid is usually caused by a difference from one side of the vehicle to the other. Some causes are: difference in traction of the tires, difference in braking, different wheel diameter and/or difference in weight distribution.The cause can be difficult to discover. Watch closely as the vehicle skids to a stop. I can remember an instance that took a couple of hundred runs to figure it out. In that case, it was something rubbing against one tire momentarily as the brakes were applied.

If it happens as the vehicle runs down the track, it is probably associated by "wheel hop". I observed this many years ago with mousetrap vehicle when speed was a factor. The vehicles were made as light as possible so they could accelerate faster. Small imperfections and dirt on the track could cause the vehicle wheels to hop and change direction dramatically.

Our skid definitely isn't wheel hop, but I do think it might be the difference of the weight of one side to another. How would you figure that out? would you make an imaginary line through the center and mass everything to the right and left of the line?

[Jocool]

it could just go to fast. down the speed. or you might want to brake both wheels. what kind of braking do you use?

[fleet130]

It might be the difference of the weight of one side to another. How would you figure that out?

You might try suspending the vehicle from 2 strings tied to the center of the front and rear axles. Add/remove or move weight around to make the vehicle balance from side to side. The goal is to the weight on both sides equal. Moving the battery pack/holder is one way to balance the vehicle from side to side. It's also desirable to have more weight on the braked axle, although too little weight on the other axle can problems.

If the suspended vehicle wants to "turn turtle", the center of mass is above where the strings are attached. You can place a small digital balance under each wheel (one at a time) to measure the weight imbalance.

Other considerations:

Once wheels start to skid, they have less traction. Any slight difference in traction from side to side or front to rear can translate into lateral (sideways) motion.The vehicle DEFINITELY needs to have even braking and equal weight distribution from one side to the other.

Front wheel braking can help a lot. When the brakes are applied, some weight is transferred from the rear axle to the front axle. This reduces the traction on the rear axle so it's easier for the rear wheels to skid. With front wheel brakes, the weight transfer increases the traction on the braking axle and makes the wheels less likely to skid.

A higher center of mass increases the amount of weight transfer during braking. This is good with front braking , but bad for rear wheel braking. Too much weight transfer can cause the rear wheels to lose traction and skid sideways.

If the rear wheels skid, any slight difference causes the vehicle to start turning sideways. This turns the front wheels and the front of the vehicle moves in the opposite direction of the rear wheels, turning the vehicle even more. If the front wheels skid , the rear wheels turn in the direction of the skid, reducing the amount the vehicle turns sideways.

[sciolympian]

thanx for all the suggestions. our buggy is a bit more aligned. still got the jitters about the competition on march. 27........

[new horizon]

good luck!
if i were you i'd start testing ASAP if you haven't already. a well tested buggy will do better than one without much testing.

[sciolympian]

yeah, we've been testing it a lot!! by the way, does anyone like the NEW ORLEANS SAINTS?

[Jocool]

i like them! also good luck. make sure you have a checklist of all the things to go through before each run. it helps a lot.

[sciolympian]

i like them!

If you do, join the scioly saints fan club by adding WHO DAT!!! to your signature.

[sciolympian]

I wish I had some more time to tune up our battery buggy. We just found a problem in the axle. I hope its fixed quickly!!