I can add a few LPR experiences. The first
photo below is from an Estes Gnome launching on a
1/2A3-4T. Evidently the clay nozzle cracked, you can see
the vectored thrust in the photo. It barely cleared the
launch rod, then gave up and dropped to the ground.
The video's kinda funny, I had my camcorder set up
on a tripod and you see me run into the picture and
stamp out the grass fire. When I inspected the motor
afterward there was no clay nozzle present anymore.
The rocket was ok and flew again that day.
The second photo is from an Estes Blue Ninja launching
on an E9-4. When I built the rocket, I made the motor mount
so that it could use a D or an E engine. This was the first
flight on an E for the rocket and for myself. Same story
as above, the nozzle cracked and the rocket never left the
launch pad, although this time it didn't start a grass fire.
The fin can melted from the heat, though, and the bottom section
of the rocket was totaled. Later I realized that I had used
the wrong size igniter plug for the motor - I had used the
larger white plug that goes with a D12 engine and not the
smaller black plug that goes with the C11 and E9 motors.
I also realized that if I had followed the instructions
and placed the rocket 8" above the blast deflector,
the fins might have not melted. Ah well, live and learn.
I chalked it up to experience and headed to the hobby store.
jeff