Friday, October 5, 2012

Launch Prep - Some Hurdles Part 4

I'm flying the Midget for the first time this weekend.
The Semroc Midget instructions showed me how to adapt short engine casings for the 13mm A10-0 and 1/2A3-4 engines.

18mm Casings were cut to 1 3/4" long for adapters.
The Semroc instructions say you can glue the 13mm engines into the casing, but I prefer to friction fit them. I could use the 18mm casings again if I pull out the engines right after the launch when they are still warm.

The fit was tight so I did an inside peel of one spiral wrap.


The 13mm engine was friction fit with a few wraps of masking tape.

Ove the years I've started wrapping the masking tape in a spiral or barber pole fashion. The engine is twisted as it it slid into the adapter. Twist the engine the same direction as the spiraled tape.





Here's the 13mm engine and 18mm casing adapter being slid into the upper stage of the Midget.

From the Semroc Midget instructions this illustration shows how the two stages are joined.
I did a friction fit of the engines separately in the upper and lower stages.

After fitting both engines, booster engine was slid forward and out. The upper stage engine was left in the upper engine mount.
The booster (in it's casing adapter) was taped to the upper stage engine (still in it's casing adapter, in the upper mount)
After both engines were clear taped together, the booster was pressed back into the booster and both sections slid together.

Be careful as the two stages are slid into position, the fins cross over each other a little bit.

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