One of the secondary affects of the chassis flex is that, as the speed increases and the chassis bows more, it actually reduces the angle of attack of the rear wing which then reduces down force and because of the lever affect reduces the bending moment into the chassis. Also the flex increases the angle of attack on the front wing which really keeps the front pinned to the ground.
The drivers module on Dixon's car really only took one good hit when it hit the wall but it certainly did it's job. There have been a number of these types of failures and it appears that it is just something that NHRA tolerates. It certainly does appear, as Sparky said, that the chassis first failed in the horizontal plane as the nose appears to be taking a right turn and then the aero forces took over and broke it in two. The pictures of the bare chassis that Doug posted certainly illustrate the "flexy" design of the front of these cars. All of the tubes have periodic vertical and horizontal tubes to keep them more or less in place but nothing in the way of diagonals to increase bending resistance. Flex is such an important part of the way these things are "designed" to work, although maybe a diagonal or two in the horizontal plane, which would have minimum effect on vertical flex, might be a good idea.
Rex
