Commanche-3 Build Question

I am building a Commanche -3, a three stager, as one of my winter projects. Things are going pretty well, but there are two disturbing features. The first is the the first and second stages don?t have thrust rings. The first stage takes a D motor which fits into the body tube and bumps up against the coupler tube which may take the pressure. The second stage though only takes a smaller C engine in an engine mount in the body with no thrust ring. To load the second stage engine, you are instructed to take the second stage to the top stage engine and then slip the second stage body over that ?snuggly? :0

What stops the second stage from simple being left behind when the engine ignites? Is it just friction?

Another issue is that even the top stage engine does not have an engine hook. My experience with a two stage rocket is that the ejection charge will dislodge the engine from the body of the lower stage and come tumbling to the ground. At the last CMASS launch, I over heard one of the old hands complaining about exactly this issue. How should the boosters, and for that matter the top stage engine be held in place when specifically designed not to?

Thanks for the advice.

Nick

> Is it just friction?

Yes, but you will need 2 types of tape, masking and cellophane. I would think the 3rd stage must have an engine block. If not you can fashion an engine block by sawing off (hack saw) the top 1/4 inch off a spent engine.

Read this. Here is a link to Estes Techinical Report 2 (TR-2) on multi staging (starting on page 3 of this file...) www2.estesrockets.com/pdf/2845_Classic_Collection_TR-TN.pdf

It takes a little practice to mount engines with tape. You need enough tape wrapped around the engine so it doesnt come out, but not so much that you cant get them out after recovery. Practice on a 1 stage rocket with a BT-20 body tube and just an engine block (no engine hook). After a few flights you\'ll get the hang of it.

The best tool I have in my range box is a 1/4\" wood dowel about 2 ft long. This is very handy for getting the spent engine out of the body tube on a 1 stage rocket (or top stage of a multi-stage). Slide the dowel down the inside of the body tube from the nose cone end. Just before you get to the engine, the dowel will catch on the engine block. Let the dowel bump over the engine block and catch on the fore end of the engine. You can then press out the engine by holding the body tube in one hand and the dowel in the other. Just be sure you have bumped past the engine block before you push (otherwise you\'ll be pushing on the block and get nowhere fast).

-Alan