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My 7 year old is a tiger cub and we are doing our first car. I found a design online and cut it out today.
Any tips on getting some speed, painting, etc?
Well looks like im a bit late to help you. There are several forums out there on this, as there are actual leagues that run year round, and other forums just for Boy scouts.
The first thing to find out is what is legal, what do your rules call out. If they allow for a lubricant that is dry on race day, use Krytox or other type of lube that goes on wet but then you remove it all, works better than graphite for under 10 runs. DO NOT Break in this lube. If you can only use dry lube, there are several varieties of lube out there with mixes of graphite and something else that is better than pure graphite (smaller particles).
Center of Gravity 1.2 - 1.5 " in front of rear axle as mentioned has proven good. Get your axles as far back as possible to get the CG as high on the track at the start as possible (maximize potential energy). If you have to use the slots, turn the car around from whats pictured so the front end is longer than the back. If you can make your own slot but maintain distance between axles, move them back so the rear wheel is flush with the back of the car.
Rub graphite into the side of the car where the wheel will touch.
Can you mod the wheels or not? Polish the wheel surface, Remove the mark left by the mold (sand is smooth) o the tread part of the wheel.
have a small amount of weight you can add or subtract (pennies are simple and cheap) at weigh in come in a bit heavy and lighten until 5 oz NO LOWER.
But ultimately the most important part, is WHEEL ALIGNMENT. Test roll the car on the floor with a straight line and see which way it pulls, try to get it to go as straight as possible, (reduces friction losses of hitting the center rail). Go to the forums on how to best align, its an art not a science and takes time and patients.
As I stated above, these are all points my daughter can explain how to do and why you do them. Though the wheel alignment is still one we are not good at cause the cars have been finished to late, and she is done working on them. So not much goes into alignment.
Finish, sand sand sand. Then get some spray paint. Spray paint is easy to do and by far the best finish. There is some automotive spray paint out there that allows metalic looks, multi chromatic ... Kids even a 7 yr old can spray paint and have a finish that will look awesome (assuming they paid the price and sand sand sand). After the car above, my daughter went to a much simplier car the next year that was A LOT easier to sand.
Remember have fun, its not about the race or the car... its about spending time with your kids, teaching them skills and learning togeather.
Just Triing
Triathlete since 9:56:39 AM EST Aug 20, 2006.
Be kind English is my 2nd language. My primary language is Dave it's a unique evolution of English.