I always thought this BT-30 illustration was strange.
The BT-5s and above are spiral wound.
But the BT-30 tube drawing, that 'aint no parallel wound tube!

That drawing is from the 1973 Estes catalog -
Enlarge to see what's wrong!

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__________________
Hans "Chris" Michielssen
Old/New NAR # 19086 SR

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