Quest Q-Jets

Discussion in 'Propulsion' started by RIB, Aug 14, 2017.

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  1. Jun 12, 2018 #91

    rockets

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    Yes, Aero-Tech/Quest customer service is AMAZING! :)
    I've always had a great experience with them, and they've always fixed their mistakes, if they ever do (Which is pretty rare)
    5 stars for their customer service! :)



    Thanks,
     
  2. Jun 17, 2018 #92

    gltruett

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    I just received a few packs of Q-Jets I had ordered a few weeks ago before I read about the problems some are having. One thing I discovered is they fit very well in the Estes 18 to 24 plastic adapter. If you have a rocket with a 24mm mount that is light enough for the Q-Jet it may be a way to use them.
     
  3. Jun 17, 2018 #93

    BEC

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    I need to do more measurements but am finding that it's not as simple as "they don't fit in BT-20". As it turns out, sometimes they do. I'm learning both that some of the Q-Jets I have on hand are larger in diameter than the quoted spec (per Gary R on Facebook, casings are supposed to be 0.698 +/- 0.003) and that some "BT-20" tubes, notably those blue Estes motor mount tubes that have been in kits for 25+ years seem to be a tiny bit undersized. Put the two together, add a little tube shrinkage around a motor-tube-to-centering ring joint and you have a situation where a Q-Jet just won't go in. But they slide right into the Citation Patriot I just built for example - without even threatening to peel the label off.

    As I say, more measurements are in order.

    I flew five more Q-Jets today....and the two A3-4s had KILLER ejection charges. But no misfires and one flight in particular was really nice.

    added later: now I'm really confused. I just tried some of today's spent Q-Jets and a couple of others in the same blue motor tube that made me draw the conclusion yesterday that it's undersized - and except for the ones with the label partially peeled back and wrinkled, they went into it.

    I also found my old (well, 9 years or so old) Quest Astra - they won't go into it. ....more measurements....and taking better notes....needed.
     
  4. Jun 17, 2018 #94

    gltruett

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    I took a few minutes this morning to do some measuring and experimenting. The B4-4 and B4-6 I have both measure exactly 18mm at the ejection end which is the same or very slightly larger than the nozzle end. My A3-6 went a tiny bit smaller at 17.95mm. Most of my low power rockets are built from Semroc parts. The Q-Jets fit in all my Semroc #7 tubes as well as the one or two Estes BT-20 tube rockets I have. Strangely enough, the one very tight fit is an old Quest Nike Smoke, it went in but after firing getting it out may be a challenge.

    I went ahead and removed the labels from one motor out of every pair while in the comfort of my shop. They all peeled right off and a quick swipe of 3M Adhesive Cleaner removed all traces of goo. Probably took less than 10 minutes to do 3 motors.
     
  5. Jun 18, 2018 #95

    shreadvector

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    One of our members flew a B4-4 in an Estes Monarch on Saturday.

    He got the motor from Charlie at NSL. I do not know the date code since our club member removed the label for fit.

    Flight was perfect.

    Delay time seemed to be very close to 4 seconds - the longest I would estimate was 4.5 seconds.

    Ignition was perfect using the 3/64" heat shrink tube installed next to the initiator.

    Ejection charge was perfectly sized. I suspect that this was from a batch of motors produced after the initial feedback provided, as they stated that all motors were now being made with the reduced-to-proper-levels ejection charge.

    I have no idea why the first batch of B4-4 motors dated 050118 have the 6 or more second delay time. it would be pure speculation to guess that maybe the motors were either built with the 6 second delay installed or mislabeled.

    I'm itching to buy a very large number of all these motors since I like the performance and initiators.Just waiting to get official word of the casing diameter revision and updated instructions (which will include max liftoff weights for each motor and delay time as well as the info on using the 3/64" dia heat shrink which will be included).
     
  6. Jun 18, 2018 #96

    heada

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    I haven't looked but have they been approved for import into CA?
     
  7. Jun 18, 2018 #97

    shreadvector

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    They are classified by the CSFM as "Model Rocket Motors".

     
  8. Jun 19, 2018 #98

    solid_fuel

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    When we expect the C & D motors to go on the market?
     
  9. Jun 19, 2018 #99

    RoyAtl

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    Gary was saying mid to late July.
     
  10. Jul 6, 2018 #100

    ATGM

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    Hey Everyone,

    Just wanted to drop in and let you all know that we have been monitoring the thread and absorbing your feedback. The issues that were mentioned will all be taken care of with the next iteration of Q-Jets. C and Ds will be shipping Late July/Early August and will fit all brands of 18mm motor tubes. Thanks again for the feedback!
     
  11. Jul 6, 2018 #101

    solid_fuel

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    Have you addressed the extra powerful ejection charge issues as well?
     
  12. Jul 6, 2018 #102

    ATGM

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    The ejection charge was adjusted from .5 to .3 a day after LDRS ended.
     
  13. Jul 6, 2018 #103

    cwbullet

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    Woo Hoo!
     
  14. Jul 6, 2018 #104

    solid_fuel

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    Excellent. The 18mm D engines have me pretty excited. In fact I have already built rockets for reloadable 18mm D engines. These will make life simpler.
     
  15. Jul 19, 2018 #105

    cwbullet

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    I read about the G11 and G12 but I have not seen a diameter on them. In what motor mount will they be used?
     
  16. Jul 19, 2018 #106

    tbonerocketeer

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    29mm
     
  17. Jul 19, 2018 #107

    Bat-mite

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    Sorry I am just joining this thread, and I don't have time to read the 180 previous posts, but I wanted to alert you to my experience with the Q-jets. If this territory has already been covered in this thread, my apologies.

    At MDRA last month, a gentleman was there who wanted to test a Q-jet vs. an Estes of the same designation. I happened to have two identical rockets prepped for flight -- same weight, same model, etc. We put an Estes B4-4 in one, and a QJ B4-4 in the other.

    I fully expected the QJ to outperform the BP motor. We even used the same igniter in each, so that the only difference between the rockets was the motor itself.

    The Estes B4-4 flight was gorgeous. Not so for the QJ. The rocket went off the pad, arced right, and lawndarted, much to my son's chagrin. Ruined his rocket.

    I was really surprised that the QJ was so underpowered. Quite a disappointment.
     
  18. Jul 19, 2018 #108

    cwbullet

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    I need a low weight carbon fiber 29 mm rocket now.
     
  19. Jul 19, 2018 #109

    jlabrasca

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    Did you use an Estes igniter in the Q-jet, or a Q-jet initiator in the Estes rocket?

    After we had similarly underpowered flights with the B4-6 and A3-6 Q-Jets, one of the club members, with a connection to Quest, suggested we were not placing the initiator correctly (not getting the pyrogen far enough up into the grain).

    Somewhere in the 180 previous posts there are mentions of the section heat shrink tubing on the Quest initiators (this was present, but ignored on the B4-6 initiators we launched. The heat shrink is missing from the initiators that came with our A3-6 motors). If I understand correctly, the heat shrink tube is meant to plug nozzle when the initiator is seated.
     
  20. Jul 19, 2018 #110

    Steve Shannon

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    Igniter placement is very important in the Q-jet motors. They are composite core burners, not BP, and thus require that the igniter go all the way up. Placing an igniter towards the aft end would almost guarantee lackluster results.
     
  21. Jul 19, 2018 #111

    Bat-mite

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    I certainly know all of that, but I'm sorry to say that I was not the one who inserted the igniter. The other guy did (can't remember his name). I assumed he knew what he was doing, and all I did was supply the rockets and put them on the pads. That'll teach me. :mad:
     
  22. Jul 19, 2018 #112

    solid_fuel

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    Never let another man fly your rockets.
     
  23. Jul 19, 2018 #113

    solid_fuel

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    From what I have heard the G11 doesn’t have enough thrust/weight to even safely lift just itself off unless used with a thrust vectoring stabilizer. These motors are not designed to be used with any regular model rocket that uses a rod or rail. They were designed to be used with the automatic thrust vectoring stabilizer. I have also heard they might be useful as an upper stage motor in a two stage rocket. Again everything I posted is from hearsay and other sources. I have no firsthand knowledge.
     
  24. Jul 19, 2018 #114

    Charles_McG

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    From the info posted on the Book of Faces this morning, the G11 would lift a 220g rocket at the 3:1 limit. With a fair liftoff kick of 22N.

    I don’t think 220g would be hard to do for a launch-it-and-lose-it rocket.
     
  25. Jul 19, 2018 #115

    solid_fuel

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    Updated info. My info was also more than a day old. :)
     
  26. Jul 19, 2018 #116

    Charles_McG

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    Sometimes a day is a long time.

    I loaded the G8 thrust curve into OpenRocket and put it in my 1/5.5 scale Nike Apache. It’s an interesting velocity curve. Depending on the sustainer ignition delay, it changes speed slightly up or down and then just holds there, balanced against drag.

    She would go high.
     
  27. Jul 19, 2018 #117

    solid_fuel

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    Doh! G8. That’s the motor thought I was referencing in my above post. All info I posted was in reference to that motor. Again all from memory (not so good) and still also second hand info.
     
  28. Jul 19, 2018 #118

    shreadvector

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    Q-Jet Initators come with a bit of heat shrink ON the leads that is used to tell you that you inserted it all the way.
    The new batch comes with an extra piece to insert NEXT TO the initiator in the nozzle. It DOES NOT "PLUG" the nozzle. it allows the nozzle to vent during ignition and it holds the initiator in place so it does not fall out or spit out until the motor ignites fully.

    The A3 and B4 motors have low thrust. The Estes B4 has a higher initial thrust to get the model moving fast off the rod. The Q-Jet A3 and B4 motors need to have a clearly stated maximum liftoff weight for each delay time. it will be lower than the Estes weight. New instructions should have this, but I have not seen them yet.

    If your model is "heavy", then use the C12 or D16 motors with appropriate delay time.
     
    Steve Shannon and Robot-Engineer like this.
  29. Jul 26, 2018 #119
  30. Jul 26, 2018 #120

    kuririn

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