End of summer update and data dive!
I ran a couple of casual track days in June and July, with no real changes to the car. At the 2nd event in June I was feeling confident, so I requested a test ride to move up to the advanced group with Turn2 lapping. Unfortunately, by the time the primary instructor had time to do the ride along, it had started pouring. Doing a check ride in the rain with all the nannies off was a bit nerve wracking. I haven’t driven much in the wet and I think it showed. I slid and waggled my way around some pretty slow laps, but did my best to be consistent and aware. Thankfully, the instructor took mercy on me and gave the green light to move up!! Sweet!!
At the first track day in July, I enjoyed the pace of running with the A group, but never seemed to piece together a good lap. Right after to the lunch break, I was checking my tires before heading out on track and discovered that one tire appeared to have some cording. I swapped to my backup set of tires (RS4s) and discovered that 3 of the 4 SC3R tires had cording on the inside edge. I had been a little concerned about the wear and think this is due to a little too much toe in both the front and rear, but the car had been driving fairly well. I had been noticing a little mid corner understeer, but the car had been very stable under braking and on throttle. I have a couple sets of 3R tires ready to go since that crazy ebay deal...
A month later I decided to do some aero testing during an oddly cool august day. I spent the day swapping canards(small canard(SC) and Large ZLE canard(LC)), and tire blockers(TB), adjusting the wing angle(W#) and managed to beat my previous PB twice. I ran the same setup first and last runs of the day to try to bracket the data for environmental changes (intake temps went from 65 to 81 degrees F). It was a little difficult to pull consistent numbers from the data, but what I got seems helpful.
For drag considerations, I used top speed on the main straight and high speed acceleration rate (110-130 time delta to avoid the 3-4 and 4-5 gear changes) to find the effects of each component. Pulling the values from each sessions fastest lap, showed some decent numbers. My baseline top speed went from 136.8mph at the start of the day to 137.7mph at the end, which was the opposite of what should have happened given that it was nearly 20 degrees warmer. Maybe it was the ~hundred pounds of fuel? Idk. The data was consistent for wing AOA changes. Adjusting the AOA from 0 to 5 to 10 degrees lost me 1.7 and 2.5 mph respectively. Accel rates were a little less consistent but at least correlated with more drag slowing me down. Removing all front end aero bits(canards and tire blockers) and setting the wing to 0 AOA, did net me another 1mph on the straight and slightly lower accel times. I’m not sure why the tire blocker run went so poorly. But keeping the TB on and adding the small canards got me within a tenth on the 110-130 times and about 0.5mph at the end of the day. Maybe there is some sort of combined effect of the two. The ZLE canard lost a little top speed and accel compared to my SC/TB combo. Not surprising given the aggressive size and angle of the canard.
For lateral acceleration, the data was pretty noisy and harder to pull meaningful info from. I tried averaging the lat accel over a 2 second period to find a sustained peak G to help eliminate noisy peaks from bumps and drops. The Average lateral G and Average Combined G per lap might provide some insight but it really is hard to tell if anything truly stands out. I’m not sure why the ZLE canards showed so poorly, nor why the Average G per lap showed such little deviation. If you take the Average G per lap as real, then its clear the wing changes added DF, but it also shows that the changes at the front of the car had minor effects and the first and last runs establish a good bit of noise in the data.
I’m satisfied with the drag data but the DF data left me wanting more. So I found another possible solution and I……..leave you with a cliffhanger!!