For those that have not heard of the "Brickwalling effect" ...it means that the wing section is not equal both sides and so as you get up to very fast speeds the air hits the top of the wing so hard as the flow now is not the same both sides and the plane will violently go straight down or up as if its hit a brick wall. Its fine if it goes up but ya have a heart attack if it goes down .....in which this case it did ...theres no time at all to shut down so do it high or find a different wing section pylon racers have this problem from time to time at around 170 mph.