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  1. #1
    Join Date
    19th February 2017
    Location
    The world, probably
    Posts
    480

    Designs I'm proud of...

    I'm starting a thread of designs I'm somewhat proud of... I'll try to put together some basic instructions as well, but I won't guarantee anything.

    This will be a similar idea to Neil_W's half-baked design thread but the other end of the assembly line- finished designs that people might be interested in cloning.

    I'll start off with with my #1 favorite scratch build, and possibly my favorite rocket period- my BT-60 Boosted Arcas. It flies great 2-staged on a D12-0 to E9-6 or C11-0 to D12-7 (could step it back to a D12-5) or in plain Arcas mode on just about any 24mm motor. I also have flown the sustainer on a B6-2 for an interesting flight profile- very much a low and slow flight.

    When I first built it I was planning on tumble recovering the booster. Yeah, not gonna happen.
    Click image for larger version. 

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    So the current iteration of the booster uses a technique I saw in a Peak of Flight newsletter that I can't find at the moment. It's built as a rear eject rocket but still vented as you normally would for a gap stage. The idea is that the pod stays in until the upper stage lights, but the upper stage motor creates enough kick to push it out. What typically happens (at least in the one flight I've flown in this configuration) is that the pod makes it about halfway out, and the parachute kinda deploys. It creates plenty of drag not to lawn dart though.

    Here's some renderings to make it make a little more sense:

    (Scale modelers- I know my paint scheme isn't great, I couldn't really find a good picture when I was designing it.)

    I'll post some real pictures at some point soon.
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    Attached Files Attached Files
    NAR #104043

    crmrc.org

  2. #2
    Join Date
    19th February 2017
    Location
    The world, probably
    Posts
    480
    Putting together a quick BOM for the Arcas:

    36" of BT-60 (4, 8, 10, 14" sections)
    3" of JT-60 (2- 1.5" couplers)
    15.75" of BT-50 (3.75" MMT, 8" MMT/stuffer, 4" stuffer w/ vents)
    1" of JT-50 (rear-eject tube coupler)
    2" of 3/16" lug (1/2" booster, 1 1/2" sustainer)
    1/8" to 3/16" balsa:
    -4 sustainer fins, 2.5" root, 1.5" tip, 1.5" tall, 1" sweep
    -4 booster fins, 4" root, 2" tip, 1.5" tall, 1" sweep
    4 standard 50-60 centering rings, one with notch for shock cord (my booster CRs are ply along with one of my sustainer CRs)
    2 50-60 ply centering rings with 4- 1/8" holes, one with notch for shock cord
    1 50-42mm ply or cardstock CR w/holes (booster fore "lip")
    2 50-60 ply CRs w/ holes and enlarged ID, at least 3/16" thick or 3/8" thick total (booster "shoulder")
    1 BT-60 coupler bulkhead w/ eye
    Recovery hardware of choice
    4 dowels, 1/8"x3 1/2"
    2.75" engine hook for booster (optional)

    NAR #104043

    crmrc.org

  3. #3
    Join Date
    15th October 2016
    Location
    Huntsville AL
    Posts
    1,907
    Any updates here?
    "I'm at least 70% confident about whatever I say (90% of the time)"- college me

    NAR 101195
    Level 1: Big SAM, 9/10/16

  4. #4
    Join Date
    19th February 2017
    Location
    The world, probably
    Posts
    480
    Quote Originally Posted by Nytrunner View Post
    Any updates here?
    Probably, at some point...

    The Arcas is currently sitting in its corner waiting for a chance to fly again. I'm aiming to fly it in Feb with an ArdIU onboard.

    There are several other designs I'm looking to put on this thread- just need a few more round tuitts...

    Sent from my LGL44VL using Tapatalk
    NAR #104043

    crmrc.org

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