Tight NC on MadCow FG 2.6" Black Brant

Discussion in 'High Power Rocketry (HPR)' started by snrkl, Dec 5, 2018.

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  1. Dec 5, 2018 #1

    snrkl

    snrkl

    snrkl

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    Folks,
    I am finishing up a 2.6" Madcow BB FG build, I have sanded both the ID of the BT and the OD of the NC shoulder such that the NC slips in without slop, but I have noticed that the NC fit is tight, and prone to binding unless removed extremely straightly... I am concerned about over sanding either side of the equation and ending up with a sloppy NC fit..

    This is my first FG BT/NC build, so I am not sure what to expect here.. All the other NC's I have flown have all been plastic (polystyrene?) nose cones...

    My first concern is the NC jamming on ejection charge.. Given I am flying with motor eject, I was not planning on ground testing, but the more I think of it, I think I will have to before the weekend... (which means building a charge well and fake motor tube...)

    My question is this: how have others who have built this kit found the fit, and are there any tricks to FG body tube and NC setups?
     
  2. Dec 5, 2018 #2

    Kallahan11

    Kallahan11

    Kallahan11

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    Sand the nosecone shoulder, you can always add a thin coat of epoxy or worse comes to worst add a layer of 3/4oz fiberglass.
     
  3. Dec 5, 2018 #3

    Keisling

    Keisling

    Keisling

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    If the nosecone fits but is tight, sometimes you can just twist it around a few times and the fit improves. The friction between the two FG surfaces rubbing together acts like a very fine sandpaper.
     
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  4. Dec 7, 2018 #4

    snrkl

    snrkl

    snrkl

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    This was the answer.. I sanded the NC shoulder, a little more at the aft end and it now slides in and out nicely, and didn't end up being a sloppy fit.. Thanks for the advice @Kallahan11! :)
     

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