#61
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About the fin dimensions...I did some searching on rec.models.rockets and found a couple threads discussing the fact that it appears Estes issued two different fin patterns for this model. Kurt did a lot of detective work on this issue!
from http://groups.google.com/group/rec....7bfa950df986464 Quote:
and from http://groups.google.com/group/rec....146892e1b43b770 Quote:
I created RockSim files and I think I see why Estes increased the fin size. Using the Barrowman equations, the original 2-7/16" root length fin (dimensions from the RMR post), and C6-5 engines, the static stability margin is .77 (using the RockSim equations yields 1.17). Increasing the fin size (3" root, rear overhang) yields a stability margin of 1.37 (Barrowman) or 1.65 (RS). Kurt's fin pattern offers a stabiliby margin of .86/1.27. Attached are the RS files for both Kurt's fin and the 3" fin from JimZ. The nose is modified per my model. If anybody want to model the original BT-20/BT-60 internal structure, you are welcome to it! |
#62
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The drawing I did was from an actual kit, where I scanned in a ring and drew it up from that. The only thing that was changed was the pattern for the engine bells, the ones from the kit were way, way off and were unusable. IDK how that happened but it was.
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#63
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Wow, 1997. A lifetime ago
Actually, a career ago... Quote:
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#64
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I see many GT models painted w/ a yellow strip at the top of the booster tube. The Estes instructions don't call out a yellow stripe, and ROTW show the top of the tube to be silver. I searched NASA's website to find launch pictures of all the manned Gemini missions, and only GT-3 seems to have a stripe -- all the others are silver. I can't find a really hi-res image of GT-3, but that color almost appears to be the goldish-anodized aluminum color similar to some of the images of the Titan II in the missle tube. I have attached a montage (L-R GT-3 to GT-12).
Anybody know why the yellow stripe is on many models? |
#65
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It is only on a GT-3. If you look at the serial number on the airframe it must be 12558 if it is manned. The Grissom/Young mission was the only manned airframe which carried the marking. Gemini 1 and 2 also had the band, but GT-3 was the last to carry it. David Weeks has it on his drawings from RealSpace, but I am not sure how he documented the band. I long thought is was a radio transparent section much like a radome. I replicate the band using a 1/2" stripe of Microscale Dark Dulux (TF-39)
__________________
Gravity is a harsh mistress SAM 002 NAR 91005 "The complexity of living is eminently favored to the simplicity of not." Last edited by jharding58 : 01-30-2011 at 06:52 PM. |
#66
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Finished painting the GT--I used an ink-jet decal for the interstage detail and "United States". Its not perfect, but I am pretty happy with it!
I used Kurt's recommendations about the fins, used Lexan from Tower Hobbies, and Weldon #16 to glue it all together. |
#67
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I don't know what you are talking about; it looks very good to me. How thick is your Lexan? How did you cut it? Score and break? Bill |
#68
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Thanks...the "tube" is 0.02 in. thick, and the fins are 0.04 in., just like Kurt recommended in one of the links I posted above. I used a piece of 2.25" dia metal barstock to wrap the 0.02" and bake it to stress-relieve. Yes, scoring and breaking worked really well. I originally was going to use a bandsaw, but thought I would try s&b first, and liked it. |
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