Race review and question
- Thread starter AUPatrick
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- Nov 24, 2011
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Just because a light wheel can't carry more momentum on it own, doesn't mean that it's going to be slower. It will always be propelled by the momentum of the weight it carries. If you take a gram off of each wheel energy won't be wasted in having to turn that wheel and you can add that weight to be carried creating more momentum. This is just my uneducated opinion.
It will be very interesting to really see how close you are txchemist, especially between the 1 gram and 2 gram wheels. I say just the flip flop on those two. I've been wrong before and I'll be wrong again somewhere down the road.
If we build the cars per the rules, the SS 2 gram wheeled car, would lose all day long against an SP 1 gram wheeled car. I say this because the SS car has to carry the 4th wheel and has more frontal area to cut through the air. Drop the NDFW on the SS car and race them heads up. Now you have a 2 gram wheel vs. a 1 gram wheel competition. The dynamics between the cars has also changed because of the different wheel weights. The SS 2 gram wheel car axles do not bear as much load per axle in the wheel bore as the SP 1 gram wheel car does. So does friction become the enemy of the lighter SP wheels car over that distance?... Theoretically the 2 gram wheels should hold more energy than its lighter counterpart over that distance... Would an increased axle diameter in the 1 gram wheel remove the ill effects of the higher load? More surface area, a larger boundary layer of oil, is it enough to offset the assumed higher friction???
Needless to say the 63 foot track will bust theories or prove them true.
If we build the cars per the rules, the SS 2 gram wheeled car, would lose all day long against an SP 1 gram wheeled car. I say this because the SS car has to carry the 4th wheel and has more frontal area to cut through the air. Drop the NDFW on the SS car and race them heads up. Now you have a 2 gram wheel vs. a 1 gram wheel competition. The dynamics between the cars has also changed because of the different wheel weights. The SS 2 gram wheel car axles do not bear as much load per axle in the wheel bore as the SP 1 gram wheel car does. So does friction become the enemy of the lighter SP wheels car over that distance?... Theoretically the 2 gram wheels should hold more energy than its lighter counterpart over that distance... Would an increased axle diameter in the 1 gram wheel remove the ill effects of the higher load? More surface area, a larger boundary layer of oil, is it enough to offset the assumed higher friction???
Needless to say the 63 foot track will bust theories or prove them true.
txchemist said:
what do you think about the weight position on a long track....is it essentially only a minor issue so still more weight in the rear, or is all the weight over essentially two wheels in the rear going to cause more friction over the long flats that will slow down a car versus a car with the weight in the middle which now may have less force right at the bottom of the hill but with the weight spilt between 3 wheels, less weight over just one area, maybe it will not slow down as much on flats and can catch up and maybe even pass the other car assuming it has enough time and track to do so....
But im the first to admit we really are taking a change of a gram or less and moving the weight about an inch forward perhaps so not sure if the other issues and ideas have more effect than weight placement in the long run.
But im the first to admit we really are taking a change of a gram or less and moving the weight about an inch forward perhaps so not sure if the other issues and ideas have more effect than weight placement in the long run.
G
Guest
Guest
GravityX said:
On the long track my gut tells me that GX is on the mark.
"I am shivering with anticipation".
I have some questions from W&K to answer that I will get to later,
but I am now realizing I have no info on this 63 ft race- is the track for ALL races this month going to 63', or are there special rules ( I can't find any) just for the 63' race?
My calculations were to simply take existing classes and run them on the longer track. If there are different possibilities, clue me in and I will crank out a new set of estimates.
My calculations were to simply take existing classes and run them on the longer track. If there are different possibilities, clue me in and I will crank out a new set of estimates.
I believe the rules remain the same, I was only stating the differences between the SS and SP class that would not make it a fair race between the 2 gram wheel and the 1 gram wheel. Now based the calculations you stated are more than likely spot on, but still not a fair race based on current build design parameters. Basically not an apples to apples comparison. I feel if the builds were allowed to be built physically the same by appearance you could then get a fair measure of the 1 gram vs. 2 gram wheel comparison over that 63 foot length. Based on current build specs you cannot put a 1 gram wheel on an SS legally and race it. Of course you can put a 2 gram wheel on an SP car but now you have to re-weight the car because of the heavier wheel. That's all I was saying.
W&K Question --
[what do you think about the weight position on a long track.]
Now 63 ft is NOT a long track in the sense that it is long enough for strange things to take place. In a race situation on a 42 ft track where your car was pulling away in the lead, and you got the wiggles near the finish and got beat, sometimes the turbulence of the cars around you cause it and it doesn't happen all the time. either more steer or move the weight a bit forward might fix the wiggle, but slow every run of your car down. If you had a bit of speed to burn, you now have a better car. If you didn't have any speed to give up, you just made a nice stable looser. Will more cars get the wiggles on a 63 ft track?.
If you want to test your car out , let it go lower and lower on the ramp until you are clocking in a 4 sec run. Now your car will be running even a bit slower than on the real track, but looking for wiggles will be valid. Once you have fixed potential wiggles, the question of best weight distribution to overall friction is the same as on a 42 ft track. Many do not even mess with an exact COG, but design close and then tune a bit with both a movable weight and steer to achieve top speed. If you get the speed you want on a 42', and you do not see wiggles on the slow test- I do not worry about the possible uneven friction on all wheels because it is already acting over 42 ft and you have optimized for it. Now on a super long track- well that could be different, but you also would have heavy wheels winning on a long enough track..
.
[what do you think about the weight position on a long track.]
Now 63 ft is NOT a long track in the sense that it is long enough for strange things to take place. In a race situation on a 42 ft track where your car was pulling away in the lead, and you got the wiggles near the finish and got beat, sometimes the turbulence of the cars around you cause it and it doesn't happen all the time. either more steer or move the weight a bit forward might fix the wiggle, but slow every run of your car down. If you had a bit of speed to burn, you now have a better car. If you didn't have any speed to give up, you just made a nice stable looser. Will more cars get the wiggles on a 63 ft track?.
If you want to test your car out , let it go lower and lower on the ramp until you are clocking in a 4 sec run. Now your car will be running even a bit slower than on the real track, but looking for wiggles will be valid. Once you have fixed potential wiggles, the question of best weight distribution to overall friction is the same as on a 42 ft track. Many do not even mess with an exact COG, but design close and then tune a bit with both a movable weight and steer to achieve top speed. If you get the speed you want on a 42', and you do not see wiggles on the slow test- I do not worry about the possible uneven friction on all wheels because it is already acting over 42 ft and you have optimized for it. Now on a super long track- well that could be different, but you also would have heavy wheels winning on a long enough track..
.
Earlier W&K question ----[what about the weight position....in peoples experience, does a car that is weighted more forward actually reach the bottom of the hill faster but because the weight doesn't stay on the hill as long does not have as much speed after the transition and the car with the weight farther back which comes off the hill with more energy now can overtake the first car given enough track length].
This is what would happen if each car was identical except for where COG [or COM] is.
This is what would happen if each car was identical except for where COG [or COM] is.
G
Guest
Guest
Totally amazing! Only a half a car length difference.
Hey TX,
Which offers the greater potential for advantage, COM, or aero?
Say a 5/8" car no fenders, vs. .185" car with fenders? Can you calculate the advantage from this sparse info?
Thanks in advance.
Hey TX,
Which offers the greater potential for advantage, COM, or aero?
Say a 5/8" car no fenders, vs. .185" car with fenders? Can you calculate the advantage from this sparse info?
Thanks in advance.
much thanks Tx!
Does that essentially rule out putting weight anywhere but the rear (barring loss of stability if too much) no matter what length of track there is (within reason of course LOL).
If true, then it certainly is one less thing to have to think about when this 63' track race comes around!
WK
Does that essentially rule out putting weight anywhere but the rear (barring loss of stability if too much) no matter what length of track there is (within reason of course LOL).
If true, then it certainly is one less thing to have to think about when this 63' track race comes around!
WK
Laserman- the drawing is just generalized to show that on curved tracks, the centers of gravity all hit the bottom at the same time ( assuming everything else is identical) and the amount of difference at the finish line is more for the same length track as the inclined plane BestTrack- but different lengths will result in more or less car differences.
On COM vs. air drag, no top racer is stacking 2 cubes high to get that COM way back because the car would be slower with added air drag from the thicker car even if he could overcome the stability problems.
W&K, except for a slight weight tweak for stability and speed on whatever track you normally set up for, same set up for 63' track if you check for slow roll also.
EXCEPT if you get to tune on the 63' before the race, because predicting the track will be a guess, but that you can help with drift adjustment.
On COM vs. air drag, no top racer is stacking 2 cubes high to get that COM way back because the car would be slower with added air drag from the thicker car even if he could overcome the stability problems.
W&K, except for a slight weight tweak for stability and speed on whatever track you normally set up for, same set up for 63' track if you check for slow roll also.
EXCEPT if you get to tune on the 63' before the race, because predicting the track will be a guess, but that you can help with drift adjustment.
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