Friday, January 17, 2020

Semroc (Centuri) Excalibur KV-43 Build, Part 3, Engine Mount


The engine mount tube had a small "stab" cut meant for the upper bend of the engine hook.
I extended the left side of the slot with my knife using the flat back side to square it off.
I didn't want to punch the engine hook through the stab slot and tear up the tube.



The Kevlar line gets a loop knot and is set under the upper bend of the engine hook.
TIP: There is very little space between the engine mount tube and the outside lower tube. Tie the knot so it will end up over the top of the engine tube when the mount is inserted. If the knot were tied closer to the top of the hook, you might end up with a bulge showing through the outside tube.




The fit of rings over the engine hook is too tight.

Cut a shallow notch on the inside of the rings (inset picture) so they can slide over the engine hook.



The finished engine mount fit was too tight in the ST-8 tube.



The centering rings were sanded down with 220 grit on a block. It took some sanding to get a good slip fit.

5 comments:

  1. If you peel the outer white paper layer on the rings the fit is pretty good

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    Replies
    1. Hi Anonymous,
      I do both - some peeled, some sanded.
      These rings weren't thick. I didn't want to risk peeling too much, sometimes more layers come off than you'd want. On this one I had more control by sanding.

      Delete
  2. Hey Chris!: I peeled the outer ones on mine also, got a pretty snug fit. Overdrove the mount into the body tube by about 1/8" but it was stuck good. Going to try and fly it that way.

    Sincerely,
    J.W.

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    Replies
    1. Hi J.W.,
      It's a tall rocket with pretty good sized fins. It should still be stable.

      Delete
  3. Good point, you can't un-peel it!

    ReplyDelete