Mid vs low

Discussion in 'Mid Power Rocketry (MPR)' started by tmazanec1, Nov 8, 2019.

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  1. Nov 8, 2019 #1

    tmazanec1

    tmazanec1

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    I know there is a qualitative break between mid power and high power (in fact there are four...levels one thru three, then amateur rocketry), but is there a qualitative break between D and E engines? Or just another power of two?
     
  2. Nov 8, 2019 #2

    Steve Shannon

    Steve Shannon

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    Hmmm.
    There are breaks based on legalities, FAA regulations, and certification levels (which vary based on which organization you join.)

    For all of them, there’s no difference between D and E motors, at least based on impulse.
    CPSC rules prohibit G or over motor sales to under 18 years of age. There are other rules as well.
    FAA rules establish Class 1, Class 2, and Class 3 flights. That’s explained elsewhere, but most high power
    Tripoli has three certification levels which are the same as NAR. CAR has four levels, splitting 1 and 2 between H and I.

    FAA used to differentiate between low power and mid power. They no longer do.
     
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  3. Nov 8, 2019 #3

    Bat-mite

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    I would like to know what "qualitative break" means before trying to answer this question.
     
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  4. Nov 8, 2019 #4

    neil_w

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    Only significant difference between D and E is that D requires 15’ launch distance, E requires 30’.

    Other than that, if you can fly a D then you can fly an E.
     
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  5. Nov 8, 2019 #5

    Nytrunner

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    There's no official designation of 'mid-power' that I've been able to find outside of the hobby's own discretion, but it's easy to draw the line since E's and up require 30' standoff distance.
    Although at E impulse, the range of composite motors opens up and you have much more flight options (you can use effects motors, lift electronics and trackers, etc..)
    Plus 20-40 N-s can get you some serious altitude on a light rocket. (E9/12 puts a Magician a 1/4 mile up)


    But an E will help you lose your rocket better :)
     
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  6. Nov 8, 2019 #6

    Tyler P

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    Es are also longer than Ds. Yes, you can launch them on the same gear (given that you launch Es from 30' away) but the rocket itself has to have an E-capable mount. Also, some E BP engines are 29mm vs 24mm. Anything above E12 for Estes is 29mm. If you launch composites, you can find all sorts of different configurations in 24mm.

    I always understood it as being E through G is mid-power. Given that, I do know that some G engines are over a certain impulse and can only be launched under an L1 certification.
     
  7. Nov 12, 2019 at 5:04 PM #7

    jqavins

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    I've occasionally heard it stated as just F and G, calling E low power. Is that erroneous, or is it a matter of opinion?
    If it's accurately a G motor then it's under 160 Ns of impulse, but it can still be an L1 motor of it exceeds 80 N average thrust or 125 grams propellant mass.

    But then, the limits of MPR vs. HPR are off topic, and the topic of another thread right here at the watering hole.
     
    Last edited: Nov 12, 2019 at 5:11 PM
  8. Nov 12, 2019 at 5:09 PM #8

    neil_w

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    I don't think there's any official distinction between low power and mid power. I routinely fly E motors in rockets that could only reasonably be called LPR, but also in some (e.g., Trajector) that are pretty clearly MPR. E is sort of a transitional motor class.

    But again, it doesn't really matter. The distinction has no significance.
     
  9. Nov 12, 2019 at 5:17 PM #9

    Nytrunner

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    Exactly. Regulated distinction is agnostic of "impulse class" until you get to the line before amateur rocketry (class 3)
    Class 1: under 125g propellant, under 1500g vehicle weight (NFPA 1122, model rockets)
    Class 2: Everything above class 1 and below 40,960 N-s (NFPA1127, high-power rockets)

    The hobby created the impulse classes to easily categorize motor power, and the Nat Orgs were allowed to define the high power certification levels.
    Mid-power is really an informal classification that helps clue folks in that these flights take a little more consideration than say, a B6.
     

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