D powerd Der Red Max

Discussion in 'Low Power Rocketry (LPR)' started by jester5900, Mar 5, 2014.

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  1. Mar 5, 2014 #1

    jester5900

    jester5900

    jester5900

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    I'm building a estes Der Red Max that is D powerd. Do I need to add nose cone weight? Were should the center of gravity be at? And would that CG be with the engine in or out? Thanks in advance for any info offerd.
     
  2. Mar 5, 2014 #2

    mikemech

    mikemech

    mikemech

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    My der Red Max has a 24x70mm motor mount. Flies great.
    My next one will have a 24mm mount without the thrust ring. I'll use a 24mm Estes motor retainer so I can fly F reloads. RockSim says no problem. An Aerotech F39W shows .9 caliber stable. Maybe put 5-6g nose weight in that one.
     
    Last edited: Mar 5, 2014
  3. Mar 5, 2014 #3

    K'Tesh

    K'Tesh

    K'Tesh

    OpenRocket Chuck Norris

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    I'd suggest that you download Open Rocket... Find the Der Red Max's .rkt file (rocketreviews), and play with the motor config (you can get CG w/and w/o the motor). Then you could save the file as a .ork and upload it here. I'd do this myself if it wasn't for the fact I'm currently at a computer where I can do it.

    [​IMG]

    If you want to start from scratch, you can go to my nosecone thread, download the PNC-60AH .ork I've uploaded there (save it as a DRM), then "build" it while playing with the settings as well.


    Good Luck!
    Jim
     
    Last edited: Mar 5, 2014
  4. Mar 5, 2014 #4

    jester5900

    jester5900

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    Were does it show the CG at? I'm at 5.5 inches from the rear of the rocket?
     
  5. Mar 6, 2014 #5

    K'Tesh

    K'Tesh

    K'Tesh

    OpenRocket Chuck Norris

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    My simulation has the length at 16.49"
    CG at 11.156" from front (5.334" from rear)

    [​IMG]

    I'm not 100% on my simulation's shapes, I'm about 1mm too short in the span, 1mm too short on the tip chord and trailing edge when I compare my fin templates to my actual DRM fins. I'm also nearly .25" longer than some of the stat's I've read about the DRM.

    Mind you, my simulation is also designed to take 24mmx95mm E engines.

    View attachment Der Red Max.ork
     
    Last edited: Mar 6, 2014
  6. Mar 6, 2014 #6

    scsager

    scsager

    scsager

    Slightly burned-out old guy

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    If you are planing to fly on a D12 motor, additional nose weight is probably not critical.

    However it's very easy to pack a half ounce of clay into the tip of the nose cone. This will not be so much weight as to rob much performance, and it does provide a margin of stability by moving the CG forward.

    Measure out the correct amount of weight, roll the clay between your hands - making a skinny "tube" that will fit in the hole at the base of the nose cone. Then pack it tightly into the tip by ramming it down with the eraser end of a pencil.

    Art clay = about $5 for a one pound package at an arts and crafts store.

    A1VJ_1_20130221125891109.jpg
     
  7. Aug 18, 2019 #7

    Red7Fifty

    Red7Fifty

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    I like to mix up a small batch of 30 min epoxy, and drop a few old misc screws into the nose for weight. Just don't mix up too big a batch of glue, it will kick off heat as it cures, and you don't want to deform the plastic. At least now, I have a use for those crappy screws in my junk drawer.
     

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