Quest D16 vs Estes D12?

Discussion in 'Propulsion' started by billdz, Sep 18, 2019.

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  1. Sep 20, 2019 #31

    BEC

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    Here are data from today. At least in my case, the D12 has a significant advantage. It was really nice and calm. Both boosts were pretty much straight up. I actually flew two pairs of flights like this, but my most abused AltimeterThree refused to share the data from the flight on my last D16-6 so here are D12-5 vs. D16-8.

    Added: My stubborn A3 shared the data with my iPad. So, here are the graphs from the first pair of flights (second pair of pictures).

    I am gratified by the consistency between the two D12 flights and can't explain the big difference between the two D16 flights. But either way, the D12 wins by a big margin with this model.

    One more thing: I just weighed the actual spent casings from a pair of these flights today....and the more contemporary D12 is three grams or so heavier than the one I weighed earlier (but there’s much more residue inside the casing, which is probably why). This means that once they're completely burned out there is little difference between the D12 and D16 in an Estes adapter in mass. Now during coast as the delay grain is burning - that's beyond me.
     

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    Last edited: Sep 20, 2019
  2. Sep 20, 2019 #32

    billdz

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    Well, that's pretty much definitive. Bernard, thanks for the tests.
     
  3. Sep 20, 2019 #33

    neil_w

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    Did some inspection of those flight graphs in an image editor. Take this all with a grain of salt. Full tabular data of the flights would obviously be more precise.

    At T+0.5 seconds: D12 at 50', D16 at 55'. So maybe the D16 gets going just a bit quicker (although the sims generally show the D12 faster off the rod).
    At T+1 second, D12 and D16 both almost exactly the same around 130 ft.
    At T+2 seconds, D16 is at 280', D12 at 325'. D12 pulling away here.

    So, based on this, we'd expect a drag race between the two to be pretty close for the first second or so, and then the D12 will start to pull away. I would still like to see that.

    Thanks @BEC for the tests.
     
  4. Sep 20, 2019 #34

    BEC

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    Neil, if you really want to delve deeply into the data give me an email address (maybe in a PM) and I can send you the data from all four of yesterday’s flights. AltimeterThree’s app makes such data sharing, in the form of a .xlsx file, easy.
     
    Last edited: Sep 20, 2019
  5. Sep 20, 2019 #35

    neil_w

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    Here's an altitude graph of the first three seconds of flight, based on @BEC's data:
    upload_2019-9-20_15-22-9.png

    They both get off to approximately the same start (although OR shows higher speed off the rod for D12, it's not visible in this data), then for the first ~300 ft the D16 jumps ahead, and then the D12 passes it.

    Overall the flight characteristics are not that much different, other than that the D12 keeps going longer and higher.

    Interesting how the two D12 flights are almost identical, whereas there's a bigger difference between the two D16s.

    Here are the acceleration curves which pretty closely tracks the appearance of the thrust curves (obviously):
    upload_2019-9-20_15-32-35.png

    From these charts it does look like the D16s hold their own with the D12s at the beginning, but looking at the numerical data, from about 2' the D12 acceleration gets somewhat higher, which seems to explain the sims showing higher speed off the rod. It's not a big difference, but it's real.
     

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  6. Sep 20, 2019 #36

    Nytrunner

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    D16's higher sustained thrust -> higher drag during boost
     
  7. Sep 20, 2019 #37

    BEC

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    Yes....this to me is why the D16 doesn't really take a model much higher than a C12 does, at least in the cases that I've flown. The C12 blows the Estes C6 away with only 1 more N-s, but the D16 is only an incremental improvement over the C12 even though it has another 2.5 N-s. But boy does a small model scoot on the D16, and you can visibly see it continuing to accelerate going up, which is fun to watch.

    And before someone asks, I have not yet done an A-B test between the Estes C11 and the Q-Jet C12. That would be very interesting to see.
     
  8. Sep 21, 2019 #38

    Alan15578

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    In the old NAR drag race event you got one point for first motion, one point for lowest altitude, and one point for longest duration. I think this would favor the D16 over the D12. The first motion is always the crap shoot. I don't trust the above simulations. You really need to fly the drag races and see which motor the judges perceive as having the first motion. I always preferred the A10 to the A3 in NAR Competition.

    In practical terms, it only matters which motor gets to end of launch rod with the fastest speed, say at 1 meter.
     
  9. Sep 21, 2019 #39

    BEC

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    Flying a D16 in an NAR Drag Race event would be interesting in that well over half the time they spit once before they take off. That would lead to a discussion about exactly what "first motion" means.... :eek:

    It also makes me wonder when Drag Race was removed from the Pink Book. It's not there now, but it's in a printed 2014 edition I have.
     
  10. Sep 21, 2019 #40

    jadebox

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    For informal drag races at our local launches, we never define the rules before hand. This allows each of the competitors to claim victory: "Highest altitude," "First to land," "Closest to the pad,"* ....

    In general, however, adult flyers usually cede victory to young flyers.

    * Closest to the pad is usually awarded when the flyer's rocket fails to launch.
     
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  11. Sep 21, 2019 #41

    BEC

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    Sounds like a good plan.

    Since I flew my last D16-6 trying to answer this question, I need to order some more from you, Roger. I’m low on -4’s too....
     
  12. Sep 22, 2019 #42

    dlrflyer1967

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    Science.......it’s almost like there’s a point to rocketry...
     
  13. Sep 22, 2019 #43

    BABAR

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  14. Sep 22, 2019 #44

    Scott_650

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    Considering that you pay a very little weight penalty using a QJet with the Estes 18/24 adapter doing the 24mm conversion would give you a lot more motor flexibility - building an Outlander that way could be worth the effort.
     
  15. Sep 22, 2019 #45

    BABAR

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    Good point, but in my case I am less interested in motor flexibility than just getting it up and down in one piece. From an altitude perspective, I’d be happy with anything over 100 feet so long as it came down okay (May even prefer something lowest power that still gets it safe and straight off the pad, doesn’t weather cock too much, and then goes with minimum altitude.). Based on prior reviews, I am uncomfortable with using an Estes C, don’t think I would ever go with a 24 mm E.

    Going with 24 mm with adapter DOES let me choose between an Estes D and a Quest D. If I knew a priori which would be better, especially if I knew it was going to be the Quest D, I was thinking stock is easier. Are you thinking it may fly better on the Estes D?
     
  16. Sep 22, 2019 #46

    BABAR

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    https://www.rocketreviews.com/compare-motors-508946.html
    Comparing Estes and Quest Ds
    Looking at the thrust curve, for a really draggy rocket, I was thinking the Quest gets it up to speed faster, burns out sooner, only thing I wonder about is the delay, kinda wish Quest had a 3 second delay instead of 4
     
  17. Sep 22, 2019 #47

    BABAR

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    Realistically, how long are most rockets still on the rod/rail? Looking at these thrust curves, is it about 0.2 seconds?
     
  18. Sep 22, 2019 #48

    Scott_650

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    There has been some reported experimentation modifying the delay of QJets by drilling down the charge similar to the technique used with larger composite motors. Though doing that to a motor not designed for modification, regardless that the method is acceptable with other motors, may violate NAR safety rules. Not a big problem launching on your own but could be a problem at a sanctioned club launch. YMMV ;)
     
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  19. Sep 22, 2019 #49

    Alan15578

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    I hope the D16 or any of the other Q-Jets don't chuf. I have no interest in reviving competition drag race. However, it occurs to me that the event could be better scored by using synchronized accelerometer based altimeters. A truer drag race, such as first to 1000 feet, without going over 1500 feet could even be done.
     
  20. Sep 22, 2019 #50

    BABAR

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    Matter of opinion. Part of most races is reacting to the gun going off (going back about 40 years to my track and field hurdling days) and not jumping the gun and getting DQ’d. I guess with rocket drag races it both rockets are wired to the same circuit, nobody is going to go early, but choice of motor and care of igniter placement are both part of the game/competition. Engine chuffing in a drag race may be equivalent to spinning your wheels in an auto drag race.
     
  21. Sep 22, 2019 #51

    BEC

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    Yes, choice of motor and igniter (this is the only other place, besides cluster models, where I will usually use one from my decreasing stock of Q2G2s) are important in Drag Race.

    Q-Jets light pretty quickly, generally. But the Cs and especially the Ds—in my experience—often “chuff” once before taking off. I have never had one chuff and not then take off. By now I’ve probably flown at least three dozen Q-Jets. Which reminds me, I need to update my entry in the Newton tally thread....
     
  22. Sep 23, 2019 #52

    jqavins

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    No "may" about it. I've heard of only two things one may do to a motor if not directed by the manufacturer, and one of them is debatable. "[R]emote the ejection charge, alter the delay grain, replace the delay charge" is certainly not either of those things.
     
  23. Sep 23, 2019 #53

    solid_fuel

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    What are the two things?
     
  24. Sep 23, 2019 #54

    jqavins

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    (I figured someone would ask.)

    OK by every source I've heard is to glue a thrust ring onto the outside.

    OK by some sources but not by others is to plug a motor with some glue: D12-5 + Expoy = D12-P.
     
  25. Sep 23, 2019 #55

    Dugway

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    Typically you plug a motor without an ejection charge, in this case a D12-0 would become a D12-P.
     
  26. Sep 23, 2019 #56

    shreadvector

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    And you would NEVER use Expoy. :eek:

    Unless you're a member of DNA (The National Association of Dyslexics) :D;)
     
  27. Sep 23, 2019 #57

    KennB

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    Well, you're half right; adding a thrust ring is acceptable. Plugging with epoxy takes you outside the NAR Safety Code.

    If you want to prevent "back" igniting a booster motor (say, in a cluster where they don't all light), you can pack some dog barf or wadding in there and put tape over the top. This is considered non-permanent and doesn't violate the NAR Safety Code.
     
  28. Sep 24, 2019 #58

    BABAR

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    Closely affiliated with DAM, Mothers Against Dyslexia.
     
  29. Sep 24, 2019 #59

    jqavins

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    Dyslexics of the world UNTIE!

    My statement was that presumably knowledgeable authorities have, in the past, stated both positions. I was completely right. I am still completely right now that another voice has said no.

    My point was that modifying the delay on a Q-Jet goes well beyond even this, since it involves disassembling the engine and putting it back together, and that there is really no room at all for doubt about that.
    Gluing on a thrust ring is totally permanent, which means that permanence alone is not the determining factor. Which isn't germane at the moment, since the topic is that you can't drill the delay on a Q-Jet.
     

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