Engine retainers.

Discussion in 'Mid Power Rocketry (MPR)' started by EvryThngIsAOk, Sep 30, 2019.

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  1. Sep 30, 2019 #1

    EvryThngIsAOk

    EvryThngIsAOk

    EvryThngIsAOk

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    So as I am new to larger engined rockets and I am learning as I go.
    What are the best types of engine retainers for larger engines.
    I have used the 29mm and 24mm thread on ones offered by estes but my current build is an Estes mega Der Red Max upgraded to a 38mm engine mount so they wont fit.
    What is the best type to use and do they require any mod to the aft ring or length of the engine tube?
     
    Last edited: Sep 30, 2019
  2. Sep 30, 2019 #2

    timbucktoo

    timbucktoo

    timbucktoo

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    Most widely used retainer would be Aeropack.
    You can buy direct from them but Wildman & Madcow carry them. Probably others too. Here is link.
    https://aeropack.net
     
  3. Sep 30, 2019 #3

    Tobor

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    Recently I've taken a liking to Giant Leap Rocketry's "Threaded Slim-Line" retainers (Link). Admittedly, GLR does not offer the range of fitment options available from Aero Pack. That said, with a Slim-Line retainer, I can recess it into the airframe for a much reduced exposed retainer profile. One neat example would be my Mach-1 RIM-66 L2 rocket w/54mm MMT.
    RIM-66 Retainer Detail-Small.jpg
    RIM-66 Retainer Profile-Small.jpg
     
    Last edited: Sep 30, 2019
  4. Sep 30, 2019 #4

    EvryThngIsAOk

    EvryThngIsAOk

    EvryThngIsAOk

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    looks nice
     
  5. Sep 30, 2019 #5

    Tobor

    Tobor

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    Thanks. Btw, I forgot to mention something that relates closer to your MDRM build. With the GLR retainer, you can recess it into the aft CR like I am doing for my Pike build. See pic #2 (in this post).
     
    mbeels likes this.
  6. Oct 3, 2019 #6

    OKTurbo

    OKTurbo

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    Big_red_daddy On this board sells a mega Red Max clone kit with a 3D printed 38mm retainer. If you contact him he’ll probably sell you just the retainer. Here’s a pic of the one I just finished.
    7072B89F-B04A-46E6-890C-5C74405B0FC3.jpeg
     

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  7. Oct 3, 2019 #7

    Sabrina

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    I like the screw-on kind too. I have used the ones made by Estes, and Aerotech (yes Aerotech) and Aeropac, and Rocketerium. I think the screw-on retainers are the easiest, but also the most expensive.

    One more thing to think about - make sure to use a good *LARGER* chute - (larger than stock) to offset the heavier than stock weight - on that 38mm Mega Max. :cool:
     
  8. Oct 3, 2019 #8

    jadebox

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    You don't need to change the length of the motor tube, but you will probably want to leave out the thrust ring so that you can use any length more. Instead of a thrust ring glued into the motor tube, the motor has a ring around the nozzle and that keeps it from sliding too far into the motor tube. Larger motors (like 38mm ones) will have built in thrust rings, but for smaller ones without a thrust ring, you use a thin strip of masking tape around the end of the motor to create one.
     
  9. Oct 3, 2019 #9

    jqavins

    jqavins

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    Stop right there. There are lots of good options and which is best depends on your preferences. Would you rather spend less money? Use fender washers catching the edge of the motor and secured to the aft centering ring with small wood screws; yes, this works just fine. Do you want low profile? There are brackets with two right angle bends that look sort of like a 7 and an L joined; one end goes over the motor edge and the other is screwed to the centering ring. Do you want easy and flexible? Use one of the screw-ons, like the Aeropack; that one has a line of adapters and tail cone retainers designed to go with the same fixed parts, but I'll bet the competitors do too.
     

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