I just launched a scratch built model of the SAAB 372 missile and it came back damaged on the 4th flight. Because of the large fwd fins I had to add a lot of weight to the nose to get the CG fwd of the CP. I have flown it 4 times. first flight was with a G64. The second time was with an H123 (aerotech promo for level 1). On the 1st Level one attempt the delay was to long and the shock cord snapped when the chute opened. The rocket remained in tact (no damage) even after my homemade body tube went 3 inches deep into very hard clay (California hardpan). This event just scraped the paint off the fwd end of the body tube. I put on a new shock cord and put a shorter delay in my motor and the 3rd flight certified me to a level 1 with the H123.
Now for the question. I was just at Dairy Aire and flew it again today on a G64. The flight was beautiful and I got several comments. However, when I went over to recover my rocket the nose cone was shattered and one of the fins was damaged on the leading edge. Further examination revealed that the nose cone had struck the fin causing both to be damaged. What would cause the nose to hit the fin like that. The shock cord is 15 ft long 3/4 inch wide elastic. The nose was 1 foot from the parachute so it could not have swung down to hit the fin. I am guessing that the Chute opened to quickly and slowed the nose cone down while the airframe, still in motion, hit the nose as it passed it.
Would this be the cause? How can It be prevented in the future?
Any tips or help would be appreciated.