Tim51
Well-Known Member
Still trying to understand what happened yesterday to my LOC Fantom EXL. Suddenly broke apart after launch with a muffled double bang. My son was was videoing it on his iPod but didn't get the moment of explosion as such. The motor was still burning after the fin can detached, and the motor ejection charge fired at that point. The attached screen caps give a visual sense of what happened.
Salvage details:
Payload bay, Av bay and electronics, shock cords, nose cone all intact.
Drogue shredded.
Main chute intact.
Fin can, 6G casing destroyed / not found (after extensive search on foot and by drone)
A portion of the forward CR was recovered, still attached to the drogue shock cord, with the steel quick link badly twisted.
This was the rocket's seventh flight - the hardest acceleration it's undergone, but it's flown well previously on a motor with a bigger total impulse but lower average (i.e. a CTI J410)
Points I've been wondering about:
1) this was the first time I'd flown it with a camera (Veho Muvi, in a case, streamlined with a nosecone (as in picture 1), screw attached to the hard point I'd built into the forward CR. Did this put too much stress on the airframe under that sort of acceleration? Fellow club members who saw before hand thought not..
2) All the ejection charges (this was a DD flight) had fired, including the motor charge (which was seen to fire in the air after the rocket came apart). This would, I assume, rule out any problem with the motor delay grain (..?)
I assuming this was a shred - that somehow the airframe crumpled. However, it blew at a very strong point - the fin can...Anyway, I thought I'd put this out there for any thoughts / feedback..
Salvage details:
Payload bay, Av bay and electronics, shock cords, nose cone all intact.
Drogue shredded.
Main chute intact.
Fin can, 6G casing destroyed / not found (after extensive search on foot and by drone)
A portion of the forward CR was recovered, still attached to the drogue shock cord, with the steel quick link badly twisted.
This was the rocket's seventh flight - the hardest acceleration it's undergone, but it's flown well previously on a motor with a bigger total impulse but lower average (i.e. a CTI J410)
Points I've been wondering about:
1) this was the first time I'd flown it with a camera (Veho Muvi, in a case, streamlined with a nosecone (as in picture 1), screw attached to the hard point I'd built into the forward CR. Did this put too much stress on the airframe under that sort of acceleration? Fellow club members who saw before hand thought not..
2) All the ejection charges (this was a DD flight) had fired, including the motor charge (which was seen to fire in the air after the rocket came apart). This would, I assume, rule out any problem with the motor delay grain (..?)
I assuming this was a shred - that somehow the airframe crumpled. However, it blew at a very strong point - the fin can...Anyway, I thought I'd put this out there for any thoughts / feedback..