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Old 11-25-2006, 07:52 PM
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Carl@Semroc Carl@Semroc is offline
Junior ??? Rocketeer
Join Date: Mar 2005
Location: Knightdale, NC
Posts: 1,470

Originally Posted by snaquin
Since the Semroc BTH-70 wall thickness would be correct at .036" given the stated tubing dimensions, should the BNC-70HAC nose cone really be 2.497" OD or I wonder if that is a typo? I would think it should be 2.247" as well?.
Thanks! The web site has been corrected. The correct diameter is 2.247". The tube was designed for multiple uses:
1. Thicker wall BT-70 for TARC rockets.
2. 1/2 scale ARCAS body tube for SLS ARCAS.
3. Tube coupler for LT-225 tubes (reason for the .003" undersize.)

The planned SLS ARCAS is the reason for the 1/2 scale nose cone. The original BNC-55AC was designed for the Estes ARCAS and later "re-used" for the Cherokee-D. The BTC-70HZ is the balsa boat tail for the SLS ARCAS.

Hawk Hobbies has a great Cherokee-3D that uses the slightly bigger version of the BNC-55AC. I wish we had have thought of that one first. 3 D engines!
Carl McLawhorn
NAR#4717 L2
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