Andrew Burns wrote:As I understand it (which isn't very well) what Paul said is on the mark, gust of wind/disturbance cause an angle of attack on the fin which results in lift being generated.
Now just throwing this out there (prob coz I was actually present at the time), the wind on the day was less than desirable. I am not discounting the fact that the fins may have let go on their own accord and I am all for the redesign which Nic and I have been discussing, however some form of wind shear is very possible, especially with the weight and size of the rocket.
Another flight earlier that day saw a coupler break on the way up which without going into great detail and taking this off topic is believed to be from a similar event of wind hitting the airframe at an angle/speed that caused severe turbulence. Unfortunately this rocket had about 8 or 9 sensors in the NC to test temps and the likes similar to Chris's project so we will have to wait for the rebuild to see data.
There are many valid points in this thread, however there is also many variables which may have played a role in the end result. I would not describe the fins as delaminated, rather torn off.