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#1
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![]() Working on a sim of the ARCAS, and I've got a conundrum... JimZ's scan of the instructions clearly states that the kit uses a JC-55C. The Estes 1971 catalog gives it as 1.3". OR's default gives it as 1.25", and Semroc says that a JC-55C is 1".
When it comes to this kit (the K-26) which spec is correct? Also need to know more about the fins... Those shapes are pretty complex, and if I can get the length of the fin support pattern, I should be able to scale both fin shapes based on that. Thanks! Jim
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. . Dreaming of making the rockets I dreamed of as a kid (and then some). "The Guide says there is an art to flying", said Ford, "or rather a knack." "The knack lies in learning how to throw yourself at the ground and miss." Launching is Optional... Landing? That Depends on Trees. |
#2
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![]() Comrade,
Note that the K-26 was a little short scale wise. The "correct" BT-55 length should be 20.24 inches as per Rockets of the World. The JT-55C I have is 1.25 inches, I have a later blue card version but it still has the balsa nose.
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NAR 79743 NARTrek Silver I miss being SAM 062 Awaiting First Launch: Too numerous to count Finishing: Zooch Saturn V; Alway/Nau BioArcas; Estes Expedition; TLP Standard Repair/Rescue: Cherokee-D (2); Centuri Nike-Smoke; MX-774 On the Bench: 2650; Dream Stage: 1/39.37 R-7 |
#3
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![]() Quote:
Thanks for the reply! You wouldn't happen to have the instructions for your version would you?
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. . Dreaming of making the rockets I dreamed of as a kid (and then some). "The Guide says there is an art to flying", said Ford, "or rather a knack." "The knack lies in learning how to throw yourself at the ground and miss." Launching is Optional... Landing? That Depends on Trees. |
#4
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![]() Let me look.
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NAR 79743 NARTrek Silver I miss being SAM 062 Awaiting First Launch: Too numerous to count Finishing: Zooch Saturn V; Alway/Nau BioArcas; Estes Expedition; TLP Standard Repair/Rescue: Cherokee-D (2); Centuri Nike-Smoke; MX-774 On the Bench: 2650; Dream Stage: 1/39.37 R-7 |
#5
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![]() The Estes ARCAS kit was used to produce the original Cherokee-D -- I found these discussions about the nose:
http://modelrocketbuilding.blogspot...art-5-nose.html http://www.rocketryforum.com/showth...okee-X-nosecone I always thought is was a secant ogive but according to Carl in the TRF thread it wasn't quite that either... |
#6
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![]() D'oh! I just realized something...
To scale a .pdf file when you are unsure of something's scale is to find out something about it that is a constant. In the file from JimZ's site the fin pattern is on the same document as the fin spacing guide. The ARCAS has 4 fins, and uses a BT-55. So, if that's the case... A BT-55 is 1.325" in diameter... Multiplied by Pi, gives us the circumference , divide that result by 4... and you get a result of how far the fins should be spaced (1.04065"). Downloading the image from the .pdf has them at 113 pixels apart (104x100)/113 = 92.035 The image needs to be reduced by 92%... And I've got my fin pattern's dimensions. Sure there's a small margin of error due to rounding, but it's the best I can do.
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. . Dreaming of making the rockets I dreamed of as a kid (and then some). "The Guide says there is an art to flying", said Ford, "or rather a knack." "The knack lies in learning how to throw yourself at the ground and miss." Launching is Optional... Landing? That Depends on Trees. |
#7
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![]() You know . . . .
You could ask Randy to make a sheet of K-26 fins and mounts. Carl had the pattern on the machine. I know because I have one. Although its not presently on the eRockets site, it wouldn't hurt to ask. . . .
__________________
NAR 79743 NARTrek Silver I miss being SAM 062 Awaiting First Launch: Too numerous to count Finishing: Zooch Saturn V; Alway/Nau BioArcas; Estes Expedition; TLP Standard Repair/Rescue: Cherokee-D (2); Centuri Nike-Smoke; MX-774 On the Bench: 2650; Dream Stage: 1/39.37 R-7 |
#8
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![]() Quote:
Talked to Randy about the ARCAS today, and he told me that they have a BT-60 based one, and another. I'm just simming this up, and not really interested in a build... yet.
__________________
. . Dreaming of making the rockets I dreamed of as a kid (and then some). "The Guide says there is an art to flying", said Ford, "or rather a knack." "The knack lies in learning how to throw yourself at the ground and miss." Launching is Optional... Landing? That Depends on Trees. |
#9
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![]() Randy might be a little confused.
The Estes K-26 ARCAS is BT-55 as you've sim'ed. Semroc had/has two ARCAS', the KS-8 built on Series 15 tubing for 18mm power and the KS-5 SLS for mid to Level 1 power on heavy-walled BT-70. If you can find one, BMS made a Peter Alway-designed ARCAS on BT-50 that's fun to fly on 13mm power . There are others, but these are the ones, I've built.
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NAR 79743 NARTrek Silver I miss being SAM 062 Awaiting First Launch: Too numerous to count Finishing: Zooch Saturn V; Alway/Nau BioArcas; Estes Expedition; TLP Standard Repair/Rescue: Cherokee-D (2); Centuri Nike-Smoke; MX-774 On the Bench: 2650; Dream Stage: 1/39.37 R-7 |
#10
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![]() Quote:
You know, I should have responded to this earlier... I'll chalk up the delay to being sick (food poisoning), and fatigue following a really bad weekend (I work weekends). I honestly didn't know that the BNC/PNC-55AC was based on this design. Thanks for the info!
__________________
. . Dreaming of making the rockets I dreamed of as a kid (and then some). "The Guide says there is an art to flying", said Ford, "or rather a knack." "The knack lies in learning how to throw yourself at the ground and miss." Launching is Optional... Landing? That Depends on Trees. |
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