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Post by fatdaddy on Jan 9, 2009 20:29:57 GMT -6
So our pack got a new track. In order to keep it close to district, we got a 49 foot best track (district is a 52 foot homemade aluminum over wood) What would you guys suggest for the COM? I have tungsten cylinders and a 1 inch tungsten round. Going RR, LF off the ground, rear wheels canted, similar design to one of Warp's cars, but not offset. I'll take all suggestions, just waiting for my PB Jig to come in from Derby Doc next week before we start cutting and drilling.
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beakerboysracing
Head in the Pine
You can pick your friends, you can pick your nose, but you can't flick your friends across the room.
Posts: 167
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Post by beakerboysracing on Jan 10, 2009 5:24:40 GMT -6
So our pack got a new track. In order to keep it close to district, we got a 49 foot best track (district is a 52 foot homemade aluminum over wood) What would you guys suggest for the COM? I have tungsten cylinders and a 1 inch tungsten round. Going RR, LF off the ground, rear wheels canted, similar design to one of Warp's cars, but not offset. I'll take all suggestions, just waiting for my PB Jig to come in from Derby Doc next week before we start cutting and drilling. With that long of a track and if it is prepped correctly with smooth joints, I would go anywhere from 1/2 to 3/4 COM. You are are going to need as much potential energy as you can get to get them to the finish line. Scott Beakerboys |
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Mr. Slick
Head in the Pine
www.PwdRacing.com
Posts: 151
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Post by Mr. Slick on Jan 26, 2009 16:28:23 GMT -6
I would caution about being too aggressive on the COM. If it is a long slope with gentle transition - AKA Challenger style, then the alignment is biggest factor in the long track. The COM being a bit forward may increase the stability for the long stretch.
Just my thoughts from the back of the pack. . . . ;D
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Post by slowsteve on Jan 26, 2009 17:21:12 GMT -6
I would caution about being too aggressive on the COM. If it is a long slope with gentle transition - AKA Challenger style, then the alignment is biggest factor in the long track. The COM being a bit forward may increase the stability for the long stretch. Just my thoughts from the back of the pack. . . . ;D Mr Slick absolutely hit the nail on the head. First and foremost, on a long track alignment is absolutely critical. Based on my experience I have found that while optimal speed on a short track (i.e. 32 feet) seems to be obtained through aggressive weighting and whatever amount of toe-in in necessary on your front dom to maintain stability/avoid wiggling... on a longer track, optimal elapsed time is to be derived via a more moderate COM (and the associated reduction in toe-in required to maintain stability/avoid wiggling). Again, this is only based upon my anecdotal experiences, but it seems logical that at some point the increased toe-in required to stabilize an aggressively weighted car more than overcomes the speed benefits offered by the addition energy imparted upon the car by that aggressive weighting. In other words (yeah, I know, I'm too wordy!), there seems to be an optimal COM/toe-in ratio that varies depending upon track length, with a less aggressive COM and less toe-in yielding the lowest elapsed times on a lengthy track. So... maybe .75" - 1" or so? For what it's worth... your mileage may vary. Steve B. |
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