Wotamalo District Races 2/20/10 Results

[Speedster]

I'm missing something. I have read in other posts Stan's comments on the Best Track versus the Circular Arc track shown in the BSA book. In our District races we first race on a Best Track and travel 29 feet. The top 8 fastest cars then move to a second aluminum Circular Arc track and travel about 40 feet. Both tracks are gorgeous. If I'm understanding the physics correctly, no car gains an advantage on the Best Track (incline) until they reach the quick curve. The rear weighted car would then have the advantage (that Cycloid thingy). When the cars then race on the Circular Arc track the rear weighted car still has the advantage. I can understand how a slower car might beat a faster car on a constant incline track where weight placement plays no part (better wheel prep) and then lose on a circular arc track to that same car. I don't understand how 1 car can beat another on a Circular Arc track and then lose to that same car on a Best Track. Has this actually happened? Does it happen often? Has someone actually experienced this? This year at our District we raced 4 times on the Best track and won each of our races. The race officials were recording elapsed times. We were one of the top 8 for the fastest times. We then moved to the Circular Arc track, ran 8 times, and took second place. I didn't hear anyone complaining they had a disadvantage because of either track. May I have everyones thoughts?

[Stan Pope]

I'm missing something. ... I don't understand how 1 car can beat another on a Circular Arc track and then lose to that same car on a Best Track.

It has to do with emphasis. A longer track increases the relative value of minimizing rolling friction. A short radius curve increases the relative value of stability. A long radius curve increases the relative value of maximizing Nose to CM distance. To get stability on a short radius curve or to minimize rolling friction, I may have to sacrifice Nose to CM distance slightly.

[Speedster]

Stan, I hope I'm not the only one struggling with this. I do understand what you just said but I don't see it happening. Let me present a situation. Rules state you must use existing axle slots. A car is built and 3 -1/2" tungsten rounds are put directly behind the rear axle slot giving the recommended 1 and1/2 ounces of weight behind the rear axle slot. COM is set at 3/4" in front of the rear axle slot using additional 2 ounces of tungsten. DT has said a COM set 3/4" in front of the rear axle slot will handle a Best track. We have 5/16" of wood in the back that can be cut off and moved up front moving the COM farther up the arc. We now have a Higher Velocity and a bigger advantage regarding the Front End Extension effect. Knowing you will be racing 29', or any distance, on a Best track, how would you design your car to be superior to the above mentioned car? Thank You.

[FatSebastian]

I hope I'm not the only one struggling with this. [...] how would you design your car to be superior to the above mentioned car?

Speedster, would you perhaps consider starting a fresh topic on this interesting conceptual question?

[Speedster]

Will do, FS. This is Super important to our scouts because of their 2 tracks at our district races. Others, such as hwsjr, apparently face the same situation.