Just opened my Estes Red Nova Kit #7266 and measured it to create a Rocksim file (see attached). When viewing the flight profile of the simulation(s) the rocket tumbles although the stability margin is around 2.1 calibers. I also get an optimal delay with a D12-3 not a D12-5 or a D12-7 as recommended by Estes. Anyone notice any unstable flights or late delay issues when they flew this design?