Some more investigation into the variability of FATS. Critiques welcome.

[Flyboy]

I was trying to see how much of an affect a slight slope in the road would have on FATS time. This was a follow on to my investigation of vehicle weight affect on the FATS time.

For this analysis I did the following. Figured out the average rate of acceleration over a 4 second FATS run on flat ground, 58-91 mph. This came out to 12.1 ft/sec^2. Then to account for gravity helping or hindering depending on the slope, I multiplied the acceleration due to gravity by the angle of inclination or declination [32.2ft/sec^2 * sin (slope angle)]. This was then added to the acceleration being developed by the vehicle. So the vehicles acceleration was either increased or decreased depending upon the slope.

The time was then calculated by using the velocity change divided by the new rate of acceleration.

I then used the time to figure distance traveled. Finally I found the feet of elevation change by multiplying the distance traveled by the sin of the distance traveled.

The graph shows some interesting results. For a 20 foot change in elevation, what should be a 4 second FATS time becomes either a slow 5 second time, or a very fast 3.6 second time.

If somebody sees a gross error in my methodology please point it out. What I think this shows is that a small slope in the road can have significant affect on a FATS time. When combined with the results from my vehicle weight analysis on FATS times it becomes even clearer that obtaining a FATS time is only useful for comparing the same vehicle, under the same conditions, on the same stretch of road.

• Post on FATS time and Vehicle Weight

[Snow Trooper]

[Gator Al (Al)]

[Snow Trooper]

[Leif S4]

[lag-sucks]

[BUFFALONOGAROpebFATS]

[Oo.et.oO]

[PSmalls::DoggieStyle]

[LCP]

...see some of the replies under this thread.

• http://forums.audiworld.com/s4/msgs/1600680.phtml