Motor Mount for Estes 4" Body Tube?

Discussion in 'Mid Power Rocketry (MPR)' started by gtche98, Apr 25, 2019.

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  1. Apr 25, 2019 #1

    gtche98

    gtche98

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    Gary W

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    I am looking at getting the 4" body tube and nose cone from Estes to build a Mega Red Max, but I want to make sure I can find a motor mount to fit in it.

    My google results show a lot of options for 3.9" tubes, but not for 4". Maybe my google skills are poor tonight...

    Is there anywhere I can get a motor mount for this particular BT?

    Thanks!
     
  2. Apr 25, 2019 #2

    rharshberger

    rharshberger

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    3.9" airframe is the same as 4", one is the inside diameter the other is the outside diameter. Centering rings from Loc Precision, Madcow and others should fit. MDRM airframe tube is the standard HPR tubing not the lightweight Estes BT-101 tube.
     
  3. Apr 25, 2019 #3

    gtche98

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    Gary W

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    Perfect - Thank you for the information!

    Gary
     
  4. Apr 25, 2019 #4

    Bat-mite

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    What are you doing for fins?
     
  5. Apr 25, 2019 #5

    gtche98

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    Gary W

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    Haven't thought that far ahead. This will be my first mid power, and the first thing that I will build that is not a complete kit, so I welcome any and all advice you might have.

    I can't explain it, but I love the DRM design, and have built a couple of the standard and mini size versions. I have wanted an upscale version, but I haven't found any clone kits (again, maybe poor google skills), and wasn't ready for 100% scratch build or figuring out the nose cone. When I saw the nose cone and body tubes on the Estes website, I thought that would be a good way of jumping into something like this.

    Again - Any advice on alternate routes to an upscale DRM would be welcomed. I don't pretend to know what I am doing, but not scared of a challenge.

    Thanks!
    Gary
     
  6. Apr 25, 2019 #6

    Bat-mite

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    Only advice I can give is to make the fins lightweight. The PSII MDRM comes with plywood fins that are honeycombed. They get covered with very thin balsa.

    You could probably try the same thing. Get some 14" ply at a hobby store. You'll need a router to core them out.

    upload_2019-4-25_10-14-58.jpeg

    Good news is that the MDRM has a ton of base drag making it very stable. You don't need anywhere near a 1 caliber stability margin.
     
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  7. Apr 25, 2019 #7

    kuririn

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  8. Apr 25, 2019 #8

    Nytrunner

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    Another lightweight option is 1/8 balsa core with 1/32 basswood on each side. Crazy stiff and light
     
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  9. Apr 25, 2019 #9

    ThirstyBarbarian

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  10. Apr 25, 2019 #10

    gtche98

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    Gary W

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    Going to get expensive to build it this way, but might be the way to go. I am definitely going to get those centering rings. I may have to think about the fins some more. Thank you all very much for all the information - you all have been very helpful!

    Gary
     
  11. Apr 28, 2019 #11

    JonathanOtt

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    Fin and centering ring pattern's attached.

    Cut a set of fins from 1/4" ply and use the CR's with the 1/4" notch and you'll be set.
     

    Attached Files:

    Last edited: Apr 28, 2019
  12. May 14, 2019 at 5:08 PM #12

    jqavins

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    No you don't. All you need is a coping saw and a drill. You drill a starter hole, take the blade out of the saw so you can pass it through the hole and put it back into the saw frame. Then start cutting. Believe it or not, people have been cutting holes in sheets for hundreds of years without routers. For nice looking pieces, cut close to the line then finish with a file or sandpaper; for simply lightening a core like this that's totally unnecessary.

    Of course, if you've got a router that makes it go a lot quicker, but it's not worth paying for one unless you're going to get a lot of use out of it. A decent coping saw can be had for under $20.
    [​IMG]
     
  13. May 14, 2019 at 8:17 PM #13

    Bat-mite

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    Fair enough!
     
  14. May 17, 2019 at 2:19 AM #14

    gtche98

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    Gary W

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    Just a quick update. I have received the nose cone and body tube from Estes. I am going to go with the motor mount and fins that kuririn pointed me to. Build will have to wait though. I have a Satrn V to build before July rolls around!
     

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