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Post by speedbump on Jan 16, 2006 16:03:25 GMT -6
The axle slots on a stock BSA block are cut 1 inch from one end and 1 1/2 inches from the other end.... Why would someone use the slots that are 1 inch from the end as the rear? (like the ones on hodges site, he has the holes drilled on the 1 inch end) From what Im reading "rear weighted"cars are faster.... Why would I use the other end of the block as the "rear"? Would make sense to have the weight located even further back from the "axle" slots. Or would this mess up the cg too much?
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Post by WarpSpeedINC on Jan 16, 2006 17:11:31 GMT -6
The reason you want the rear wheels back as far as possible, is to give the car more "Fall Time". The longer the car is "falling" down the ramp, the longer it is accelerating. As soon as the rear wheels hit the flat, the car is no longer gaining speed, and is slowing down from then on.
This goes hand in hand with rear weighting. The more weight on the rear wheels, the more potential energy the car has for a longer period. Any weight on the front wheels, is done pushing the car as soon as they hit the flat. The longer you can keep the most weight falling, the longer and harder it will excellerate.
Warp Speed
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Post by speedbump on Jan 16, 2006 18:00:07 GMT -6
yeah, I understand the "theory" and all...was just curious why the blocks were drilled on the 1 inch end and not the other (allowing you to place the weight further back behind the rear axle slot (the 1 1/2 inch end) So, I called J. Hodge, and basically he explained that's just how they are when they arrived to him. But, explained that I might run into the weight being placed too far back if I used the 1 1/2 inch end. might allow the CG to drop too far back and make the front end unstable. Oh well, safe than sorry I suppose
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Post by SpeedGeek on Feb 3, 2006 19:29:12 GMT -6
There are two factors to consider: one factor is the vertical distance the CG "falls"... the greater the distance, the greater the speed. Where the CG is in relation to the axle is irrelevant in that respect. The second factor is STABILILITY. Stabilility decreases with the distance between the CG and the rear axle.
So... it's a balancing act: increase the distance the CG falls without going going unstable. Moving the rear axle as far back as possible maximizes stability. Moving the CG as far back as possible maximizes speed.
If you cross the beams, you get something similar to this month's Gepard (sp?).
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