#1
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Looking for BT-21 or BT-20+ and odd items
Hi folks, So in my attempt to scratchbuild a Fake Wulf I have been gathering parts. What I cannot find is a BT-20+ or also called BT-21 tube I guess, and also a pretty thick 21-55 balsa centering ring. Everything else was easy enough to find, but these, well not so much. Anyone have any idea where I might buy these items?
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#2
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Try BMS or Semroc
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When in doubt, WHACK the GAS and DITCH the brake !!! Yes, there is such a thing as NORMAL, if you have to ask what is "NORMAL" , you probably aren't ! Failure may not be an OPTION, but it is ALWAYS a POSSIBILITY. ALL systems are GO for MAYHEM, CHAOS, and HAVOC ! |
#3
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Quote:
Not having the tube dimensions, I'm going to guess that the BT-20+ tubing is a slip fit over BT-20. This vintage Totallu Tubular product? http://www.erockets.biz/totally-tub...t-20-34-1-pk-1/ Or maybe the ASP variation? https://www.asp-rocketry.com/ecomme...nt=13&navPanel= ST-7 is larger than BT-20 and not a slip fit over BT-20: http://www.erockets.biz/st-7/
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-Wolfram v. Kiparski NAR 28643 - TRA 15520 MTMA Section #606 President |
#4
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Thanks everyone, so far.........
I have found everything except the 21-55 thick balsa centering ring.............but I have some leads.....
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#5
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BT-30 is an old Estes size.
OD: 0.767 ID: 0.725 Not sure where BT-20+ originated. OD 0.770" ID 0.744" eRockets (Semroc) has both. You can take a regular 20-55 centering ring and sand it until it fits. Otherwise, print out a template and cut your own. I seldom buy centering rings anymore. I usually make them from cardboard or balsa. .
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I love sanding. |
#6
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Are you doing a build thread on the scratch Fake Wulf?
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Never trust an atom. They make up everything. 4 out of 3 people struggle with math. Chemically, alcohol IS a solution. NAR# 94042 SAM# 0078 |
#7
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Quote:
Why not just sand or “Dremel-out” a fiber 2055 centering ring? BMS has those. The fiber is really tough, and lightweight. I realize you found the other parts, but for for the benefit of others, BMS, stocks several “+” style tubes that slide over a regular tube.
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Lee Reep NAR 55948 Projects: Semroc Saturn 1B, Ken Foss Designs Mini Satellite Interceptor In the Paint Shop: Nothing! Too cold! Launch-Ready: Farside-X, Maxi Honest John, Super Scamp |
#8
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Quote:
BT-20+ may be what CMR called RB-77. Their regular tube was RB-74, and RB-77 was a slip-fit over it. Apogee (Ed LaCroix version) had similar sizes of their BlackShaft tube (and maybe their regular tube too)
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Roy nar12605 |
#9
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This tubing is on erockets.biz It is also available on the ASP website. Just a slight bit smaller in diameter than the Quest size T-20 available from BMS. It should be a simple matter to enlarge the rings. A sheet of sandpaper wrapped around an engine casing works well. BTW,, the t-20+ tubes will probably be discontinued due to the change in the NAR payload requirements. Apparently it was too challenging. LOL.
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Jeffrey Deem NAR16741 CIA section 527 |
#10
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I believe that the "+" usage came from Totally Tubular.
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NAR #27085 - Oregon Rocketry - SAM |
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