About a month ago while at a club launch my Estes Challenger II lawn darted due to a failed ejection of a C11-5. The cap never broke on the motor. Thankfully thankfully the nose cone and fin can were unharmed in crash but there was no saving the body tube. The Challenger II uses the BT56 body tube that is out of production but thankfully, I had a replacement tube in my stash. One of the benefits of being in this hobby for 40+ yrs. 
Here is aftermath of the crash and before anyone mentions the burns on the chute, those are from previous flights. The cap never broke on this flight so the ejection never fired.
After a fair bit of colorful language, I disassembled the remains of the rocket and sanded down the fin can and nose cone. The BT56 tube was the correct length so nothing to do there.
Here are the main pieces to reconstruct.
For the motor mount, I cut down a scrap piece of BT50 tube I had in the parts box to 2.75". The original motor clip was reused. I cut a pair of BT50/56 centering rings from 3mm ply and grabbed a BT50 motor block.
The motor tube was sanded on the outside. A slit was cut in the motor tube 1/4" from the top and the motor clip was test fit. I then used another piece of the scrap tube to make a retainer for the motor clip. This was glued in place around the motor tube. The motor block was also installed.
Once the sleeve was dry, I added the upper and lower centering rings, attached form 500# Kevlar cord to the upper ring and added some heat shrink to protect the first few inches of the cord.
Due to the plastic fin can and nose cone, I'm going to paint the parts individually before assembly so I'll be back in a couple of days with an update.
Here is aftermath of the crash and before anyone mentions the burns on the chute, those are from previous flights. The cap never broke on this flight so the ejection never fired.
After a fair bit of colorful language, I disassembled the remains of the rocket and sanded down the fin can and nose cone. The BT56 tube was the correct length so nothing to do there.
Here are the main pieces to reconstruct.
For the motor mount, I cut down a scrap piece of BT50 tube I had in the parts box to 2.75". The original motor clip was reused. I cut a pair of BT50/56 centering rings from 3mm ply and grabbed a BT50 motor block.
The motor tube was sanded on the outside. A slit was cut in the motor tube 1/4" from the top and the motor clip was test fit. I then used another piece of the scrap tube to make a retainer for the motor clip. This was glued in place around the motor tube. The motor block was also installed.
Once the sleeve was dry, I added the upper and lower centering rings, attached form 500# Kevlar cord to the upper ring and added some heat shrink to protect the first few inches of the cord.
Due to the plastic fin can and nose cone, I'm going to paint the parts individually before assembly so I'll be back in a couple of days with an update.
