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Post by Peace Of Wood on Jan 22, 2011 15:40:54 GMT -7
Attached is a picture of the pair of cars we built for this years pinewood derby (one on left was used). All in all, a great improvement from last years car. First place den, Second place pack (84 cars). A little unsure if COM wasn't quite far enough back on car (0.9" from axle) or maybe steering was too neutral. Or, if I wanted to make excuses I could blame the fact the car was dropped after its first heat from about 3' off the ground. Car shape was inspired from the name "Snot Rocket" which my son came up with at the dinner table while talking about what we wanted to build this year. A fun build and great race. Mar 12 is a district race with different rules than our pack so he wants to build "snot rockets revenge". Aluminum track at the district race so we will likely push COM further back, dial a bit more rail into the ride, follow the boy scout motto and do our best. Look forward to advice from the members on other changes. Our pack does not allow the crimp marks on the shaft of the nails to be removed. Car that beat us was talking about how important axle prep is. Do you think the fact we left the crimp marks on the nails per rules affected the outcome? We lost by about 1". Other car was cut about 1/4" thick so I'm sure there was some aero advantage on their car as well. Attachments:
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Post by W Racing on Jan 22, 2011 19:13:31 GMT -7
You only ride on the bottom of the axles....
Place the crimp marks facing up....
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Post by Peace Of Wood on Jan 23, 2011 13:09:56 GMT -7
The axles have the crimp marks on both sides, 180deg apart. I think there is 3 marks on one side and 2 on the other. Otherwise I would have just put the mark to the top as you suggdsted. Does any one have any experiance with rule like this and what is the best method to minimize the friction while keeping the crimps (no sanding allowed).
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ljo
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Posts: 61
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Post by ljo on Jan 27, 2011 10:48:20 GMT -7
Nice cars, seven inches of wood. You technically would have been legal with the axles I gave you. We will see you at district!
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Post by Peace Of Wood on Jan 29, 2011 15:09:40 GMT -7
I re-read our rules and you are all ... It stated they could not be removed and did not say they could not be reduced or polished. As far as inspection, there is none on the axles other than the boys need to be able to say they followed the rules if asked. Thanks for the ideas. Thanks for the compliments on looks. Attached a second view of the cars. I did not remove 1/16" from the front dominant tire as we barely had the car steered into the rail (about 1" over 12'). Our pack has a wooden track with some sections that are not always aligned perfectly and on my wooden test track riding the rail down didn't seem to slow it but it sure made alot more noise which just didn't seem right. I have no timer so I rely on racing my cheater car and seeing just how close I can get to it. This makes it very difficult to determine that last critical 1" of difference. For steering alignment my center lane only has a center guide in the hill portion leaving the car to run the rest of the track for testing alignment with car at speed. I don't know if anyone else has done this but it seemed to do well for me and 2 other dads (different packs of course) that set up cars on the track this year. LJO I saved the manufacturing defect (crimps by point) nails for next years car as it will need all the speed help it can get if he sticks with the idea of building a tank.... Thanks again Attachments:
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