Pinewood derby car prep

[SciFiMan]

My daughter has a pinewood derby this Sunday, and I have a question about weight placement. Her car is done and with the full package of flat weights we have it is at 4.6oz. Is it worth getting it up to the max of 5oz.? The track is not curved, just the usual straight ski jump ramp style. And where do I put the weights for best benefit? Underneath in the middle and 50-50 balanced like a RX-8, or should it be front- or back-biased, or ? Thanks for any help y'all can offer.

 

[pb4ugoout]

i really wish i could remember my boy scouting days. i did this many many times at EXPO and won several years in a row. sorry i'm no help. my dad was a pack master tho, maybe he remembers, i'll ask

 

[Protege52003]

my two cars did well many many years ago. one had some metal melted in the front of the car (in a hole on the bottom), an my second one had a weight sunk into the top rear of the car. they both did good.....

 

[noclue119]

http://www.rahul.net/mcgrew/derby/speed.html

Weight Your Car Well



Heavier cars are faster than lighter cars, so try to get your car as close to the maximum weight as possible. It's a good idea to plan for a way to adjust the weight on race day. That way you can add as much weight as possible, or you can remove excess weight without risking significant damage to your car. If you plan ahead, you can create a way to add small metal objects (e.g., screws, BBs, coins, fishing weights) to your car on race day.

Weight distribution matters, too. I believe that the front end of your car needs to move easily so it can correct its course easily when it hits the guide rail. Your car's weight distribution determines how easily its front end can move.

Make the unweighted car body as light as possible, and keep the lead weight as compact as possible. This reduces the rotational inertia of your car.

Put the lead weight just in front of the rear axles. If the weight is behind the rear axle, your car's front wheels will tend to bounce. This bouncing will slow your car down, and it might even cause your car to derail and leave the track. The exception to this weight-to-the-rear design is if your race uses a track that gets steeper right after the starting gate. On such tracks, the weight should be forward (just behind the front axles) so your car will accellerate more quickly in the beginning.

 

[MiaTurbo]

if the wheels are really low friction, go with more weight.

 

[Cellerator]

I say balance is most important, keep balance throughout the car. If too much is on the front, if you hit a bump, it is still possible for the rear wheels to derail. If anything, I'd put some wd-40 or some sort of lubricant on the axles and sand paper the wheels like treads, it helps.