My little practical test with a pencil and two attached wheels seem to confirm as much...? (though it was rather unscientific, I'll admit
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).How? Why?WilliamsF1 wrote:Disagree on the part where car will turn right when you lift
I'd say lifting off would likely give less of a "yaw boost" to the left, but I wouldn't expect it to make the car turn to the right.DaveKillens wrote:How? Why?WilliamsF1 wrote:Disagree on the part where car will turn right when you lift
You agree that the application of throttle will produce a counter-clockwise yaw motion. So if the opposite thing happens, would there not be logically an opposite motion?
That huge right tire has more grip than the left. Under the application of throttle the disparity in grip from left to right produces a yawing motion to the left. When the throttle is lifted, the engine braking will decelerate the rear wheels, and once again the difference in grip comes into play, this time producing a yaw to the right.
That is a very viable theory, but in all respect, it does not align with real-world observation. In the following video of Jac Haudenschild, pay careful attention at 2:25. He hammers the gas, and the car immediately turns left.Tim.Wright wrote:Interesting discussion. While the tyre diameter stagger is undoubtedly to act as a differential in the corners, I'm not convinced that applying throttle in a straight line will make the car unconditionally go left.
Consider in this case (straight line, low speed) that you have the left wheel slightly more loaded due to the asymmetric CG and that the inner wheel has a smaller radius, so for a given input torque it will create a higher tractive force at the contact patch compared to the larger diameter outer wheel. These two effects would add together and possibly give the car an initial response yawing to the right before the faster rotational speed of the outside wheel causes the tractive force split to switch sides and give a yaw response into the turn centre.
In a corner at racing speeds the situation is different. There you have load transfer to the outside wheel so it is more likely to be producing a similar or higher tractive force than the inside wheel.
Remember a "diff" (or even a spool) has two jobs with conflicting targets. It needs to give the maximum tractive force (which suggests biasing the torque to the outside wheel) but it needs to keep the car stable on the throttle (which suggests biasing the torque less to the outside wheel). So its not always clear which way the driveline is trying to yaw the car in any given condition.
Spools are quite difficult to analyse in this respect because the wheel torques are somewhat indeterminate. You need to know the vertical load and mu split of the left and right tyres to know which one is giving the most tractive force.
Fair enough, though when he floors it, the first movement of the steering is to the left, not the right.DaveKillens wrote:That is a very viable theory, but in all respect, it does not align with real-world observation. In the following video of Jac Haudenschild, pay careful attention at 2:25. He hammers the gas, and the car immediately turns left.Tim.Wright wrote:Interesting discussion. While the tyre diameter stagger is undoubtedly to act as a differential in the corners, I'm not convinced that applying throttle in a straight line will make the car unconditionally go left.
Consider in this case (straight line, low speed) that you have the left wheel slightly more loaded due to the asymmetric CG and that the inner wheel has a smaller radius, so for a given input torque it will create a higher tractive force at the contact patch compared to the larger diameter outer wheel. These two effects would add together and possibly give the car an initial response yawing to the right before the faster rotational speed of the outside wheel causes the tractive force split to switch sides and give a yaw response into the turn centre.
In a corner at racing speeds the situation is different. There you have load transfer to the outside wheel so it is more likely to be producing a similar or higher tractive force than the inside wheel.
Remember a "diff" (or even a spool) has two jobs with conflicting targets. It needs to give the maximum tractive force (which suggests biasing the torque to the outside wheel) but it needs to keep the car stable on the throttle (which suggests biasing the torque less to the outside wheel). So its not always clear which way the driveline is trying to yaw the car in any given condition.
Spools are quite difficult to analyse in this respect because the wheel torques are somewhat indeterminate. You need to know the vertical load and mu split of the left and right tyres to know which one is giving the most tractive force.
http://youtu.be/L6AHPvhe3NM
given, solid axle connecting both wheels (no diff), enough traction for both wheels, I cannot imagine how you could get the car yaw right at any time during a blip on the throttle, torque difference isn't enough, speed difference of the rim of each wheel would matter more, that's my opinionTim.Wright wrote:Interesting discussion. While the tyre diameter stagger is undoubtedly to act as a differential in the corners, I'm not convinced that applying throttle in a straight line will make the car unconditionally go left.
Consider in this case (straight line, low speed) that you have the left wheel slightly more loaded due to the asymmetric CG and that the inner wheel has a smaller radius, so for a given input torque it will create a higher tractive force at the contact patch compared to the larger diameter outer wheel. These two effects would add together and possibly give the car an initial response yawing to the right before the faster rotational speed of the outside wheel causes the tractive force split to switch sides and give a yaw response into the turn centre.
I think its fair to say we all have done something stupid when we were young. He may have been a nice youn man, but he let his anger get the best of him. It is a shame, even though his actions during those few moments were very unwise.Raleigh wrote:
Got sympathy for Kevin's family and friends but little for the fool who ran into fast moving traffic to shake a fist and died.
I was thinking the samething, but The World of Outlaws is not for everyone, and lets face it they only race in US, Canada and down under so not alot of people can get to see them.strad wrote:I can see who knows something about Sprint cars and who doesn't.