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Old 04-23-2005, 12:45 PM
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CPMcGraw CPMcGraw is offline
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Join Date: Mar 2005
Location: Mobile, Alabama
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Quote:
Originally Posted by Thrustline 1
i am looking up some parts to reproduce this kit and I'm running into a snag. The BT-52S tube used I can't find anywhere. And, to make matters worse, if you go to the Ninfinger website, it shows the tube as being over 3 inches in diameter...No I know that ain't right.

Any help?


You've just asked one of the $64,000 questions of model rocketry, you know that?

This is also a SPEV tube, IIRC...

One of the things we've pretty much concluded is, there's no easy answer. Here's an example:

In the Estes 741 parts list, the diameter for BT-52 is listed as 1.114" OD and 0.998" ID. However, BMS sells their Thor-Agena nose cone with 1.010" OD and 0.995" ID. Like the lyric in "Industrial Disease" goes, "Two men say they're Jesus... One of 'em must be wrong..."

I also think we've discovered several instances where even Estes used different thicknesses of BT in different kits, but called all of them "52"...

Here's a suggestion. If you're doing all of the turned balsa work yourself, why not make a slight compromise and just use a Centuri (SEMROC) ST-10 tube? This has an OD of 1.040", which falls between the original Estes spec [highly questioned figure anyway] and the BMS spec. If you compare with the Estes spec, the ID is only 0.002" larger with ST-10. It's going to be similar to Carl's "Retro-Repro" series -- close to the original, but brought up-to-date using more modern design philosophies...

You'll probably get the kit out the door faster this way, too...


Craig [Needing to take his own advice] McGraw
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