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Old 11-10-2017, 03:13 PM
PeterAlway PeterAlway is offline
Intermediate Rocketeer
 
Join Date: Mar 2014
Posts: 35
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Quote:
Originally Posted by blackshire

In the MPC Titan IIIC kit, the core vehicle is 1.2 " (30.48 mm) in diameter, which is large enough to accommodate two 13 mm (BT-5) motor mount tubes. As in the old BT-70 size Estes Gemini-Titan II kit (see: http://www.spacemodeling.org/jimz/estes/k-21.pdf ), the Titan IIIA's motor mount tubes could be angled slightly inward toward each other. I don't know what this model's weight would be, but I'm confident that two A10-3T motors would provide good performance; so might two 1/2A3-2T motors.


I didn't comment on this last time, because I wanted to confirm my recollections of some measurements I made of the Titan III C kit a few weeks ago. The MPC kit is undersized by something on the order of 10%-20%. For instance, the boosters, which should be 1.22" in diameter, are about 1.0" in diameter. The core, which should be 1.2" in diameter, is about 1.1" in diameter. The lengths are shorter vaguely in proportion (I haven't specifically measured).

The inside diameter of the core section is about 1.05" in diameter, while two BT-5 tubes would require 2 x 0.541" = 1.82" of space. you'd have to carve away at the paper or the plastic to get that to work, and canting them outward is right out.

All in all, I think it would be about as easy to scratchbuild a flying Titan III A based on Gemini-Titan II plans and a custom conical nosecone.

Peter Alway
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