Loki M1378 vs MAC canvas phenolic?

Discussion in 'High Power Rocketry (HPR)' started by Andrew_ASC, Apr 12, 2019.

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  1. Apr 12, 2019 #1

    Andrew_ASC

    Andrew_ASC

    Andrew_ASC

    UTC SEDS 2017 3rd/ SEDS 2018 1st

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    So yeah I started looking into a L3 design for fun. A 3FNC 54mm min diameter dual deploy canvas phenolic rocket. Three CF fins of 0.1275” thickness that theoretical flutter at M3.45. Rocket is about 189 cm long and 2.27 stability margin. It predicts M2.89 and 36,700 ft in OR. I’m at work on break but curious if any has pushed MAC phenolic tubes above M2.4!?? From what I have read the canvas phenolic survives M2.3-2.4 from others flight data. Is this a feasible L3 project idea?

    I really dig the light density of the canvas. And price isn’t bad.
     
  2. Apr 12, 2019 #2

    Cl(VII)

    Cl(VII)

    Cl(VII)

    Chris Bender, Lab Rat TRF Sponsor

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    A rocket similar to what you describe has been built (carbon versus canvas though), but I don't know if it has flown yet...read and learn young one. Mac Pappy

    While it is carbon airframe, the size limitations of the 54mm airframe, and how to fit everything are laid out well.
     
    Last edited: Apr 12, 2019
  3. Apr 12, 2019 #3

    blackjack2564

    blackjack2564

    blackjack2564

    Crazy Jim's Gone Banana's

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    Mac Pappy has carbon airframe .

    Ps. I would just call Mike and ask him for an opinion.
     
    Last edited: Apr 12, 2019
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  4. Apr 12, 2019 #4

    ECayemberg

    ECayemberg

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    Checking in! Mac Pappy has flown! Since it didn't get lit at Airfest '17, it took flight on Sunday of Airfest '18. Nominal flight up and down....

    except...

    the M1378 spit the nozzle insert, which limited the altitude to about 60% of the expected altitude (23k vs. 38k'). I believe Scott has the nozzle issue resolved now.

    My personal hunch is:

    Canvas will work well under ideal conditions. IE: if the rocket flies straight, doesn't cone, doesn't encounter significant wind shear, early or late deployment, it will hold up just fine.

    However, if the rocket airframe experiences any exceptional forces other than directly in the direction of travel (see above), I'd be surprised if it didn't shred. Side loads and yaw forces would likely be problematic for canvas, IMO. Planning for less-than-perfect atmospheric or flight conditions, I'd lean heavily towards carbon (or glass) airframe.
     
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  5. Apr 12, 2019 #5

    Andrew_ASC

    Andrew_ASC

    Andrew_ASC

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    I’ll call Mike for an opinion to see if his customers have pushed his product this hard. I think the canvas phenolic is tougher than normal phenolic. I don’t want to bash his product if it works at M2.89. Fiberglass maybe a better economy alternate for this environment. Anyways thanks guys for the advice. Not out to set a record. Just trying a method where what I learn at L1/L2 transitions to L3 build.

    I’m thinking unreinforced airframe whatever I do. And not tip to tip.
     
  6. Apr 12, 2019 #6

    mike2wander

    mike2wander

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    MAC Performance Rocketry TRF Sponsor

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    I think Eric hit the nail right on the head. When in doubt go with carbon. I've personally flown my HYPER 54 to Mach 2.3 (1822) and 23k on an L1040. With the Loki 2800 case loaded there is absolutely no extra space inside. The motor acts as an aluminum liner for the canvas airframe. A longer canvas airframe to hold the Loki M1378 spit would be the same situation. If surface mounted fins were to experience a lot of flutter then I think the rules would definitely change. On the flip side....With a MAX-Q Fin Can I think the canvas would survive as long as deployment goes as planned. I think someone needs to prove us right or wrong. ;) The pics of Eric and MAC Pappy were taken at Airfest in Argonia last August
    Cayemburgh carbon.jpg cayemburgh carbon2.jpg
     
    Last edited: Apr 12, 2019
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  7. Apr 13, 2019 #7

    DavidMcCann

    DavidMcCann

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    Going for cert knocks out the fin can.

    I'd go carbon here, but as Mike said.... there's not a whole ton of open space in a rocket like this. You're basically pulling a canvas condom over a motor casing and lighting the bottom.
     

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