Thread: Pinewood Derby
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Old 02-08-2010, 11:43   #32
Snaquebite
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Join Date: May 2006
Location: Raeford, NC
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Quote:
BTW I need to find about .005 of a second.
1. Lengthen the wheel base. (If allowed)
2. Some folks believe raising one of the front wheels off the track creates less friction. Never tried it though.
3. Center of gravity, 1 to 1 1/4 inches in front ot the rear wheels. Keep the weights low in the body. The car should balance somewhere between 1 and 1-1/4 inches in front of the rear axle.
4. Once you get the wheels correctly aligned, use a small amount of super glue to keep them that way.
5. Take a pipe cleaner and polish the inside hub of the wheel. Most folks don't think about this.
6. When you lube the axels, don't just add a few puffs of graphite. Spin the wheels and work the lube in the hub. Then add a little more on both sides of the wheel.

If your rules allow:

1. Make a round paper hub cap to glue onto the wheel after final assembly of the wheels and axles. When the wheel moves towards the car body, the hub cap contacts with the axle cap before the wheel can touch the car body. The spinning wheel and hub cap just touch in the very center of the axle cap resulting in minimal friction. Even better if you put a bit of graphite in the hubcap before final glue-down.
2. Shave down the wheel width so they look like bicycle tires. This causes a very thin track contact point for less friction. It also has less mass in the wheels meaning less inertia and less energy to get the wheels spinning at the start.
3. The cap on the axle touches the plastic wheel across its surface. This means for friction to slow down the wheel. Grind away the outter side of the wheel so a thin circle around the axle hole is higher than the surrounding wheel. This causes the wheel to touch the axle cap close to the center where there is less energy wasted.

Edited to add: these last three mods are a little difficult for the kids to do.

Happy Racing
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Last edited by Snaquebite; 02-08-2010 at 12:00.
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