Q-jet motor equivalent to old Estes c5-3?

Discussion in 'Low Power Rocketry (LPR)' started by billeblurzz, Nov 5, 2019.

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  1. Nov 5, 2019 #1

    billeblurzz

    billeblurzz

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    Hey guys, I'm looking to try some of the quest q-jet motors for the first time in 18mm size. What one would be comparable to the old estes c5-3? Thank you for any replies. Bill
     
  2. Nov 5, 2019 #2

    Nytrunner

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    Interesting substitution.
    Neither Q-jet has the C5's sharp 20N spike at the front for lifting really heavy rockets.
    The C12 has just a tad more impulse, and the D16 has 3 more N-s. They both have stronger sustained thrust than the Estes C6.

    I'd say as long as your model can be safely lifted during that first 1/4 second of the burn, I'd think either the C12 or D16 will work.

    Here's the C5
    upload_2019-11-5_10-42-36.png

    the C12

    upload_2019-11-5_10-43-8.png
    and the D16
    upload_2019-11-5_10-43-59.png
     
  3. Nov 5, 2019 #3

    billeblurzz

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    Ok thank you for the excellent reply! I loved the c5-3 motor and wish it still was around! I've had special situations where they worked very well so maybe I can use the q-jet. Can they be ignited easily in a 2 motor cluster?
     
  4. Nov 5, 2019 #4

    Nytrunner

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    Clustering is not my area of expertise.
    Suggestions from those who do this sort of thing:
    -Make sure the Q-jet igniter is placed properly (be careful not to damage the tip)
    -Make sure the igniter is secured from falling out (I put masking tape over the back end, and poke a little hole for venting gas, composites take a little extra care to light)
    -Make sure the leads have enough slack so if one motor is slightly delayed, the igniter won't get ripped out (some use a stake with the leads hanging down to the aft of the rocket)
    -Make sure the launch system can deliver enough current for both motors
     
  5. Nov 5, 2019 #5

    billeblurzz

    billeblurzz

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    Thank you!
     
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  6. Nov 5, 2019 #6

    BEC

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    A Q-Jet C12-4 will give a good kick to most anything you’d use the C5-3 in as long as it’s not really heavy and dependent on that initial thrust spike to get to a safe speed—which is basically what Nytrunner said more clearly.

    The biggest concern I’d have about clustering Q-Jets is that they sometimes quickly chuff once before they light. I’ve seen this more on the D16s than C12s, but one of the two C12s I flew yesterday did this. Consequently the advice about having enough slack in the ignition leads that Nytrunner gives above is key.

    I’ve probably flown close to 50 Q-Jets by now and only had one or two ignition failures using the supplied igniters, so that in itself isn’t much of a worry. The Fast Black Jack propellant is one of the easiest composites to ignite. For igniter retention I’m using the supplied red heat shrink tubing with good results in Cs and Ds.
     
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  7. Nov 5, 2019 #7

    75Grandville

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    Speaking for only myself, I've had difficulties trying to ignite two in a cluster. The problem could be the user, the ignitors (I think I tried both stock and my own), the motors, or some combination thereof. Those attempts were August 2018 and August 2019 - I can't remember the details.

    Aaand other people posted better replies while I was typing mine...
     
  8. Nov 5, 2019 #8

    billeblurzz

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    Ok thanks. The rocket in question is a lengthened fliskits Duece that I mounted 2 gliding styrofoam space shuttles that worked well with 2 c5-3 motors. I am looking for motors to use now in place of the c5-3s.
     
  9. Nov 5, 2019 #9

    neil_w

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    I would think a C6 would work, unless it's really a lot heavier. 2 x C12 should also be great, subject to caveats re: getting them both lit.

    The C5 sounds like it was a great motor, feel bad I never got to fly one.
     
  10. Nov 5, 2019 #10

    BEC

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    Now that we know the application I would tend to agree - try a pair of C6-3s. Then maybe go for C12-4s....though I’d be a little concerned about the health of the styrofoam gliders given the progressive thrust curve of both the C12 and D16.

    I still have a few C5-3s that I acquired shortly after becoming a BAR, thanks to someone who had his Dad’s hobby shop in the basement of the house. In general they have been fun motors, but the last time I tried to fly one the LCO noted that they have a reputation for CATOing and sure enough, one blew up my Fat Boy. I probably still have a dozen or so...and of course now am more reluctant to fly them than I was before that.
     
  11. Nov 6, 2019 #11

    shreadvector

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    C5-3 motors from year code "X" would experience VIOLENT catos.

    Violent is not an acronym - I was yelling.:p
     
  12. Nov 6, 2019 #12

    BEC

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    It was violent. I just checked my motor supply. I have sixteen C5-3s left. Three have a Y year date code, the rest are from two Z year batches. I did not note in my log book what the date code of the offending motor was, but I generally report them to motorcato.org when I have them, so should have logged this one - it was in mid-March of this year. Just based on what’s in my motor box it was likely 5 Z 4.

    [added: just checked the new search function on motorcato.org - I did report it and it was 5Z4.]

    I did have a 1/2A3-0T blow on my yesterday. 31 F 5. I need to turn that one in. It does feel a little silly reporting malfunctions on motors that are, in this case, 44 years old. I did fly another 1/2A3-0T yesterday that was three weeks past its 46th birthday. It did fine.

    None of this has much to do with flying Q-Jets in a stretched Deuce, though.
     
    Last edited: Nov 6, 2019
  13. Nov 6, 2019 #13

    billeblurzz

    billeblurzz

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    Thank you so much for the excellent information everyone. The space shuttles were from a Michael's store and are solid and durable and were originally mounted to a super nova payloader and flown with a d12-3 with good lifting just to get the gliders aloft! Even used an e20 composite for great height and long gliding times! I then stretched a Duece and mounted them and decided on the c5s for their lifting capacity. Worked really well and even the owner of Fliskits was impressed. Haven't tried it again since the demise of the c5s! Maybe try two c6-3 before attempting to ignite 2 q-jets!
     
  14. Nov 6, 2019 #14

    billeblurzz

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    The all up weight with the c5-3s was 12oz.
     
  15. Nov 6, 2019 #15

    neil_w

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    Whoa that’s quite heavy, sounds like too much for 2 C6’s.
     
  16. Nov 6, 2019 #16

    billeblurzz

    billeblurzz

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    You may be right! I haven't thought of this rocket for quite a while...those c5s really did the trick though! I loved those motors...never knew about the Cato problems!
     
  17. Nov 6, 2019 #17

    jqavins

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    And that means, among other things, heavy enough wires out to the pad. Even with a good strong battery, long skinny wires can do you in. It should be at least lamp cord, not the lightweight wire found on entry level controllers.

    That makes a certain amount of sense, as the large initial thrust spike implies a corresponding pressure spike.
     

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