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Old 02-04-2017, 10:54 PM
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BEC BEC is offline
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Join Date: Feb 2009
Location: Auburn, Washington
Posts: 2,285

Originally Posted by al_packer
BT-50 was 0.950 I.D., 0.976" O.D., at least up until I departed in 1977. That just happened to be the size of a stock mandrel that Euclid Spiral Paper Tube Company had. The nose cone was a BNC-50K.

So just like the story GHS recounts in a couple of his writings of a stock firework tube setting the diameter of the most common model rocket motor (18mm), a stock mandrel drove the size of the next common size up (24mm) since the Estes "Mighty D" had to fit in BT-50, and I surmise (but don't know) that all the follow one motors (Estes Es and C11s, and 24mm composites) are all that diameter to be compatible.

I love how this stuff all connects together.
Bernard Cawley
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