I have a friend who e-mailed me last week; he's building a clone of the K-21 Estes Gemini Titan - II model. He asked me about the centering rings for the BT-20 engine tubes and the exact placement of the two holes for each ring. I don't have that information, but was wondering if any here does. If you do, can you post a pdf (or similar) file so I can forward it to him?

Many thanks in advance!

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Dave, NAR # 21853 SR.

Kurt Schachner has done the decals and templates for this. Here's the direct link.

http://www.rocketshoppe.com/decals/Gemini_Titan.pdf

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Scott D. Hansen
Ye Olde Rocket Shoppe - Your One Stop BAR Shoppe!
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WOOSH NAR Section #558

Thanks Scott (and Kurt)! That's what I think he was looking for. I've forwarded it to him. I'm sure I'll get a response tomorrow. Thanks again, I knew I could count on you guys here at YORF!

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Dave, NAR # 21853 SR.

Kurt's an expert at the fin-can making for this particular kit as well.

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Scott D. Hansen
Ye Olde Rocket Shoppe - Your One Stop BAR Shoppe!
Ye Olde Rocket Plans - OOP Rocket Plans From 38 Companies!
Ye Olde Rocket Forum
WOOSH NAR Section #558

Kurt, if you are out there - what adhesive do you recommend for the fin can?

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Got a Caribbean soul I can barely control.....

I am having an issue with the engine can for this model and I hope that you can assist. I am using Semroc LC rings (which match the patterns exactly) and I believe the correct length of BT-20G (3.5" per the Estes parts catalog). ALso I believe that I have the correct measurement from the thrust ring end of the tube for the JT-50B's. My problem is that I cannot get the geometry to work without a lot of "manipulation". The upper 2050 rings foul each other before thelower rings will reach the 2 5/8" mark. If this is supposed to be a very tight fit then I will glue with abandon - but since this is a build for someone else I wanted to ensure that this is a fairly rigid displacement fit without any slop between the two JT-50B's.

Also, could someone confirm the length of the JT-50B used on this model as being 1/2"?

Thanks in advance

Did you get an answer to your question about the JT-50B length? I have a hard time believing that they are as long as 0.50 inches. I built one when that kit was current (long ago in a place far, far away) and I don't think that they are that "fat." They certainly are not 1 inch long as described here: http://www.spacemodeling.org/JimZ/manuals/estp741.pdf

Edit.....elsewhere, Roy has stated that they are 7/16".