@dksmall,
Sorry to hear about your issues and the damage to your Rover.
You are lucky that they have started doing staggered starts. When I competed in the 2013 and 2014 Sparkfun AVCs at the Boulder Reservoir there were at least eight Rovers in each of the three heats that I ran in. On the first heat of the 2013 AVC I turned too soon on the second turn and ran inside of the hay bales, but I successfully won heats two and three to win the Peleton Class that year. The multicar starts in the 2013 and 2014 AVCs could be deadly so I had my Rover start very fast and get out in front at the start and avoid the traffic jam.
I wish that I could have been there to help you out, but I live in Southern Florida and it is very expensive to either drive or fly to Boulder now that 3DR no longer sponsors me.
" It went full throttle, throwing up dirt as it spun through the dirt. At the time I thought that was kinda cool, but it picked up speed and took off down the course. I had no radio control to stop it, but it completed the next turn nicely, went through the hoop, and started a 90° right turn, still at high speed. It hit a concrete curb and broke the left control arm." I had this happen to me after I had moved from the APM2.6 to the first Pixhawks that had become available. It turned out that the Pixhawk did not like the 6 vdc being supplied by the Traxxas ESC to the steering servo and every once in a while the Rover would take off either forward or backwards and would not respond to R/C control. Bypassing the Traxxas ESC 6 vdc around the Pixhawk servo output power bus solved the problem.
Please post your tlog and datalog files of your AVC runs and we will try to help you determine what happened.
Regards,
TCIII AVD