G78-4 mojave green lift off max weight.

Discussion in 'Mid Power Rocketry (MPR)' started by John Taylor, Aug 24, 2019.

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  1. Aug 24, 2019 #1

    John Taylor

    John Taylor

    John Taylor

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    Hello all,
    I cant seem to find information on the maximum lift off weight regarding the G78-4 mojave green 29mm reload using the 29mm 40/120 hobby casing. I found the thrust curve data, total impulse and average thrust, but no info on the max lift off weight

    Thanks for your help!

    John Taylor
     
  2. Aug 24, 2019 #2

    CzTeacherMan

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    3.5 lbs is a 5:1 ratio at liftoff. Definitely no lower than that. Anything 2.5 lbs or lower is even better (7:1)
     
  3. Aug 24, 2019 #3

    tfish

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  4. Aug 24, 2019 #4

    John Taylor

    John Taylor

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    Thanks for writing back,
    It is a 4" diameter simple rocket with mid frame separation. Empty weight is 1100 grams, or about 2.2 lbs empty.
    I know a G 64-4 weighs 151 grams, using that my lift off weight would be about 1251 grams,or about 2.8 lbs.
    Thanks much for your help!
    jt
     
  5. Aug 24, 2019 #5

    John Taylor

    John Taylor

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    Tony, I believe that motor might be different. I am using the 29-40/120 reloadable casing. I have flown many G64-4 reloads in that casing. The reload I'm talking about will fit that casing.

    Thank you very much for responding!
    jt
     
  6. Aug 24, 2019 #6

    dhbarr

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    Did you mean g76?
     
  7. Aug 24, 2019 #7

    John Taylor

    John Taylor

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    Yes G76, I'm sorry, so many motors.....brain fail....
    Yes I did mean G67-4 Mojave Green.
    Thanks!
    jt
     
  8. Aug 24, 2019 #8

    dhbarr

    dhbarr

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    Behaviorally quite a lot of difference there.

    g76 has more zip up front and a bit more total impulse.

    simfile1326_650x350n.jpg simfile1298_650x350n.jpg
     
  9. Aug 24, 2019 #9

    John Taylor

    John Taylor

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    Thank you very much. Looks like the G67 has a big hammer at the start, even more than the SU G80-4.
    It looks like it would easily lift my rocket weight at 1251 grams at lift off.
    Sorry to keep asking for information, I just bought a Google notebook, with a Google operating system that is incompatible with any rocket simulation program.

    Thanks again,
    jt
     
  10. Aug 24, 2019 #10

    dhbarr

    dhbarr

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  11. Aug 24, 2019 #11

    John Taylor

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    dhbarr likes this.
  12. Sep 11, 2019 #12

    DavidMcCann

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    I've flown 3.3 pounds in a 5.5" mini magg on a G76G.

    It's about as far as I'd take the motor, but never had an issue with the setup.

    G76G at 20 seconds

     
    Last edited: Sep 11, 2019
  13. Sep 11, 2019 #13

    STXFlyer

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    I have flown my 2.2 pound vega on a G76, it left the pad in a hurry.
     
  14. Sep 12, 2019 #14

    swatkat

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    G76G is the hobbyline reload. It has lifted my 58 Oz. 3" FG kit no issues, 4 second delay. Rocksim says 52 ft/sec of a 72" rail. So it's a good lifter.
     

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