this is a wonderful replication/reconstruction. I do hope you will be able to make the high-powered catapult now that Andy has sent you an example of this frightening piece of equipment!
Stuart Lodge can help you to fly your model with, say, and Estes motor, but if you want to use an authentic Jetex 50HT motor you will need to know how the pellets are ignited to give the necessary thrust.
Here comes a few more pictures:
The complete nose, including the motor adaptor and, thanks to Andy, the motor.
Now on to the launching ramp.
The main spar of the catapult is built up from two hardwood strips glued to each side of a plywood strip. I did 3D-print several jigs that could slide over the main spar and guarantee a good alignment and symmetry.
Next step is to copy and 3D-print the top and bottom end mouldings that hold the guide rod for the launching carriage, and the holder for the ramp trigger.
A progress report.
The ramp is coming along nicely. After printing the top and bottom ends, as well as the launching trigger with mount it was time to draw the launching carriage. Here is the main spar with bottom end and the launching trigger test fitted.
Since carriage interacts with everything else, I decided to simulate it by making an assembly with the already printed parts in the CAD, to make sure it would work out. After a few adjustments it did, and here is the result:
The launching trigger holding the carriage.
The release catch activated by the release ramp.
And I couldn't resist adding the rocket to se how it looks.
this is splendid stuff. As you know the catapult was a fearsome device - "As powerful as an air rifle" was one reviewer's comment. The plastic parts were injection moulded and of (I think) polystyrene. Will your 3D printed replica's be as strong?