X3 Testing today

The weather was much better today and I got a chance to test. Max speed today was 73mph at about half throttle. After the 73mph pass I made another pass with more throttle than the previous runs. At about 75mph the X3 blew over.

Video of 73 mph pass

Data from 73mph pass


Video of blow over pass at about 75mph

Data from blow over pass

Damage to the X3 from the blow over

The rear springs are much too soft for the extra weight of the massive motor and batteries. Stiffer springs are necessary to maintain a good rear ride height. Under acceleration the back end would squat and the positive angle of the chassis would direct all the airflow underneath the car. This caused lift and I had a blow over. I tried to minimize the up-travel of the rear shocks with spacers, but then the rear shocks would rest on the spacers and that rendered the suspension useless since there was no upward suspension travel. I also need to decrease downforce on the rear of the car. I need to trim or get rid of the rear wing. As far as I can tell the damage to the X3 is superficial. The body and front right wheel seemed to absorb most of the impact.

Overall, I am very happy with how testing went today (except for the blow over). The X3 felt very stable and very easy to drive. Acceleration was excellent. I didn't push the X3 to its limits because the spur and pinion gears are wearing themselves out very fast. I need to get a new set after the next couple runs.

I will make a couple of changes and I will be back testing soon.