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  1. #1
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    31st October 2016
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    How to attach through-wall fins to tail-cone?

    I am guessing this has been discussed many times here, but nothing too useful popped up when I searched.

    I've got two designs in progress. A 3 inch diameter WAC Corporal and a whimsical 4 inch thing of my own design. Both designs call for fins that conform to the tail-cone. The best idea I can come up with is to build the fin-can assembly separately. Do the internal fillets from the forward end, then couple it to rest of the airframe.

    I it has also occurred to me to assemble the tail-cone from sections fitted between the fins.

    Is there a better way to do this?

    NAR Level 1, Sheridan Oregon, 09/16/17 -- scratch built 7.6cm x 120cm rocket on an AT H182R.

  2. #2
    Join Date
    29th December 2013
    Location
    Bayport MN
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    167
    There are good instructions for building the fin can and filleting from the top for the wildman demon 98. I used Wildman style injected fillets on a rocketry warehouse Terminator. I may have foamed the tail cone for added strength too. https://flic.kr/s/aHskGEVhQu

    Sent from my LG-V521 using Rocketry Forum mobile app

    L1 - Madcow 4" Phoenix I180 Skidmark 1651 feet
    L2 - Darkstar 2.6" J145 Skidmark longburn 4787 feet
    L3 - Terminator 5" M1297 White Lightning 8602 feet

    TRA 15743
    NAR 30949
    http://www.rocketreviews.com/karl-tyrrells-page.html

  3. #3
    Join Date
    27th March 2013
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    Follow the link to see how I did it with my downscale of the Binder Design Velociraptor.

    Dreaming of making the rockets I dreamed of as a kid (and then some).


    NAR L1 Cert flight: Sheridan, Oregon, USA. Sept. 19, 2015. Flew Deep Space OFFl on an I357T-14A Blue Thunder

  4. #4
    Join Date
    12th September 2013
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    SE Wisconsin
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    I used both K'Tesh's info (boy, that looks weird with two apostrophes) and the instructions/build threads for the Wildman sport V2 when I did my Big Daddy based F25 Firelily.

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    Charles McGonegal
    Ciderwright at AeppelTreow Winery & Distillery
    www.appletrue.com
    NAR #103560 L1 6/25/17 Estes Leviathan CTI H175-SS
    Ad Astra Tabernamque!

  5. #5
    Join Date
    27th July 2014
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    south beloit, IL
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    2,473
    Quote Originally Posted by jlabrasca View Post
    The best idea I can come up with is to build the fin-can assembly separately. Do the internal fillets from the forward end, then couple it to rest of the airframe.
    My L3 rocket was a v2 (with boat tail, obviously). This is what I did.

    further details: I epoxied the fins just enough to have them attached to the motor mount, as well as external fillets to hold everything in place. Then I removed the forward centering ring (which was only sitting in place- not epoxied in), and did internal fillets. Then replaced the centering ring and epoxied everything down. This made sure everything was strong enough, and the fin/motor mount assembly was straight.
    NAR# 99285
    Tripoli# 16283
    L1- 4/26/2015 Madcow Cowabunga- H123SK
    L2- 11/1/2015 Wildman Darkstar 2.6- J355RL
    L3- 11/3/2017 Wildman V2 6" - M1780NT
    Woosh
    QCRS

  6. #6
    Join Date
    31st October 2016
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    Quote Originally Posted by Thorfire View Post
    There are good instructions for building the fin can and filleting from the top for the wildman demon 98.
    Quote Originally Posted by K'Tesh View Post
    Follow the link to see how I did it with my downscale of the Binder Design Velociraptor.
    Thanks (x4). So that's two four votes for a separate fin can assembly, filleted from the forward end?

    Thorfire I didn't know the term "injected fillet" Thanks for that. I've looked it up.

    Charles_McG -- I like the Firelilly. It should be a 4X cluster, though, yes?
    Last edited by jlabrasca; 29th November 2017 at 03:27 PM. Reason: hanging html-tag + two more thank-yous
    NAR Level 1, Sheridan Oregon, 09/16/17 -- scratch built 7.6cm x 120cm rocket on an AT H182R.

  7. #7
    Join Date
    15th September 2009
    Location
    Silverton, Oregon
    Posts
    1,006
    Click image for larger version. 

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    When I built Chester's Cheeto Chaser IV I used cedar strip "fillets" that were epoxied and screwed in place.


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    Dan Feller
    Silver Crest Rocket Club

  8. #8
    Join Date
    12th September 2013
    Location
    SE Wisconsin
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    Quote Originally Posted by jlabrasca View Post
    Charles_McG -- I like the Firelilly. It should be a 4X cluster, though, yes?
    At least 1 F55 was a quad cluster. The F25 was a single motor.

    My younger Boyo keeps wanting me to do a 10" full scale F25. :-)
    Charles McGonegal
    Ciderwright at AeppelTreow Winery & Distillery
    www.appletrue.com
    NAR #103560 L1 6/25/17 Estes Leviathan CTI H175-SS
    Ad Astra Tabernamque!

  9. #9
    Join Date
    31st October 2016
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    Quote Originally Posted by Charles_McG View Post
    ...The F25 was a single motor.

    My younger Boyo keeps wanting me to do a 10" full scale F25. :-)
    That's what I get for trying to show off my rocket-knowledge. In my head, I see the plans for the (F55?) Firelilly in a Doubldeday Science Service pamphlet, possibly checked out from my elementary school library. Its probably confabulated.

    My daughter is less specific in her instructions. She's placed an order for single stage 8-fin rocket (none of which may be strakes or canard fins), which requires at least two people to carry to the pad.

    NAR Level 1, Sheridan Oregon, 09/16/17 -- scratch built 7.6cm x 120cm rocket on an AT H182R.

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