## Curving variance

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### Re: Curving variance

Lorant wrote:
windu34 wrote:
Lorant wrote:We have tested and competed on countless surfaces from linoleum to wooden planks, and our car still consistently draws a flatter arc on the way back, so I don't think it is the floor. My original guess was that the string on the axle would bend the chassis and as it decreases throughout the run, would change the arc. So, I built a car meant to minimize this bending, but the curve variance is still there. What else could be causing it?
This is most likely due to oversteer on the way to the cup target point and then respective understeer on the way back due to differences in velocity (youre probably going faster forward and slower backwards). The best way to account for this is to have independent data for going forwards and backwards that is recorded along with avg velocity. However, if you determine that the velocity and acceleration is about the same every run on both the forward and backwards parts of the runs, you dont need to account for that

I have a vehicle events video posted on the Scioly.org youtube channel that you will find helpful.
Could a fan design for the drive arm help with evening out speed and thus making over/under steering more manageable?
By fan design you mean multiple arms?
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windu34
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### Re: Curving variance

Lorant wrote:
windu34 wrote:
Lorant wrote:We have tested and competed on countless surfaces from linoleum to wooden planks, and our car still consistently draws a flatter arc on the way back, so I don't think it is the floor. My original guess was that the string on the axle would bend the chassis and as it decreases throughout the run, would change the arc. So, I built a car meant to minimize this bending, but the curve variance is still there. What else could be causing it?
This is most likely due to oversteer on the way to the cup target point and then respective understeer on the way back due to differences in velocity (youre probably going faster forward and slower backwards). The best way to account for this is to have independent data for going forwards and backwards that is recorded along with avg velocity. However, if you determine that the velocity and acceleration is about the same every run on both the forward and backwards parts of the runs, you dont need to account for that

I have a vehicle events video posted on the Scioly.org youtube channel that you will find helpful.
Could a fan design for the drive arm help with evening out speed and thus making over/under steering more manageable?
That depends - if the arms of the fan are all equal length, it will just increase your acceleration and probably increase oversteer effects. The purpose of a fan system is to maintain optimal torque on the axle to improve acceleration and the efficiency of the mousetraps. Now if you made the arms of the fan successively longer so that the amount of torque each exerts on the axle is less than the previous, that may help, but I wouldnt expect it to be too significant - all you would be doing in reality is decreasing acceleration. However, if you increased the weight of your device while adding a fan system such that your acceleration and velocities during the run remained unchanged comapared to before you added weight, you should see a reduction in the effects of over/under steer variability.
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