Bertha Fans! Here's the "Rapscallion"

Bertha Fans! Here's the "Rapscallion"

Post by Kevin Forsy » Sat, 28 Oct 1995 04:00:00



All you fans of the Big Bertha (hi Jo Ann, good luck flying your Ranger...
let us know how it goes :)  I have started my latest experiment into the
Bertha family of rockets.

Those of you who spotted my post "Charring motor tubes" know about my rear-
end toasting problem with the 24mm-motored Rascal I built-- caused by open-
ended turbulence I think.  Well, since I don't think I'll be able to take out
the motor tube to replace it (and since the body is starting to burn through
too), I took inspiration from all the talk of boattails and tried one.

I took a spare Bertha nose cone, measured a circle on it using a BT-50, sawed
it off and cleaned it up so the BT-50 would fit snugly.  Put a couple of
50-60 centering rings on it, and inserted it into a ~12" s***of BT-60 I
had.  The motor tube extends about 3/32" from the end of the tail, and will
handle 24mm motors, friction fit (i.e. no motor hook).

Next step will be to cut fins using the Rascal pattern (essentially the same
as the Big Bertha/Ranger, but slightly larger).  I'll attach them so the
back end of the root is near but not at the bottom of the plastic tail, to
give the exhaust some clearance.  The curve of the cone should be easy to
duplicate.

Since it's a extended and modified Rascal, I'm calling it the Rapscallion.
If this (admittedly basic) idea is a new one, I take full credit for the
name.  ;))

/kevin
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 Kevin S. Forsyth, Programmer/Analyst
 Political Science Dept./School of Labor & Ind. Relations
 College of Social Science, Michigan State University

 East Lansing, MI.  48824-1032            phone: (517) 353-8481
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