Thread: After the Fire
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Old 06-05-2005, 08:19 PM
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CPMcGraw CPMcGraw is offline
Join Date: Mar 2005
Location: Mobile, Alabama
Posts: 5,357
Exclamation ThunderRoc "E" conversion

Originally Posted by Tweener
I'm in need of some advice... I'd like to put a 3 3/4" 24mm mount in the rocket to enable E power launches with Estes engines, and I have four questions.

1) If I choose to launch with a D, what do I use for a 1" spacer? (I'm thinking spent engine casing cut to size, cellophane taped to front of engine for ease of extraction.)

Two possibilities:

1 -- Get a 1" length of hard, black fishpaper "JT-50" coupler material.
2 -- Take two CR-2050 rings and a 1" length of BT-20. Glue the rings at each end.

Having said this, read on...

2) What E9 delay would be best for ejection at apogee?

None. See question #3.

3) Since an E9 doesn't have as high a thrust spike as the D12, will I need a longer rod than 36" for the rocket to become stable?

Much longer. Try 80". It doesn't become stable until it reaches 73". See the simulation file.

4) Will the 3/16" rod still be sufficient rather than 1/4"? ( I use 1 piece steel and not 2 piece aluminum, actually cheaper at the hardware store. )

Should be, but you need to see the simulation file (attached) for the engine selection.

I'm not rocksim literate, and when this is built it will be my first E power capable rocket. I don't want anyone to get hurt!

Don't sweat it, it comes with time. Just study the sim results carefully, and you'll get all the data you need.

This bird needs composite Aerotech motors (or their equivalents) to fly safely. The Estes BP motors just don't have the needed horsepower to kick this pig. The same applies to the Mean Machine, if you wanted to do the same thing with it.

Craig McGraw
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