Let me start by answering Scotts question about why use 1.22 as the constant in calculating lateral g forces. 1.22 is the simplified version of the real equation which should read: lateral acceleration = (2.0 x pi) squared X radius/time squared, and to find the force measured in “g” the value of 1G is plugged in using 32.174 (1.0G in feet per second per second is 32.174). When those numbers are plugged in the result is 1.2270286, rounded down to 1.227 (I am not sure who decided it should round to 1.22 rather than 1.23).
That said, using max lateral g as a measure of a vehicle performance capability is a marketing ploy used primarily by manufactures to show their vehicles performance. In reality very little about the 200 ft skid pad test relates to real world handling. The skid pad is a very controlled environment in which the vehicle is driven at its maximum speed while still maintaining its line within the circle. There is no braking, dive, acceleration, elevation change, direction change, or any other variable involved. A true test of a vehicle performance as it relates to handling can only be done on a technical road course where all of these variables are negotiated. Obviously if the driver is not a constant than the results as to how much of the ability is the vehicle and how much is the driver now come into play.
The 480ft slalom is more of a handling test than skid pad ever will be but still is plagued with the same lack of variables. I would like to see the SAE change its venue for performance testing to use a closed track that all manufactures must use when placing claim about vehicle performance as it related to handling capability.
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Dennis
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