Here's the engine mount drawing and some of the parts list.
The kit engine mount tube was a BT-ST, at only 1 1/2" long. With the engine hook slit 1/4" from the top of the tube, the engine hook and engine will extend 1/2" out the rear. This seems long to me. I found out later why it is longer.
The upcoming snap-together Min Bertha kit has a new screw on engine retainer.
A dry fit of the 5/20 centering rings found they were too tight. This required some inside peels for a good friction fit.
Here's a dry fit of the engine mount using the 1 1/2" BT-5 tube. It's short! I didn't like how much of the engine hook hangs out the low end.
More (and a fix) in the next post.
I'm apt to think that the motor extends further aft to make it easier to extract the spent motor. The way the fins extend over the aft of the rocket not only means it's harder to grasp the end of the motor, but probably also harder to bend the retaining hook to allow for the extraction of the spent motor.
ReplyDeleteHi Naoto,
DeleteThat's what I found out. In the end, the engine in my build is a bit farther inside. I can still slide in (and remove) the engine but it is a bit tight.