Delay too short on A motor

Discussion in 'Competition Rocketry' started by UberSquid, Sep 7, 2018.

  1. Sep 7, 2018 #1

    UberSquid

    UberSquid

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    I've been designing a rocket in OpenRocket for A motor Altitude competition. Right now the C class A Altitude record is 449m. In simulation I can only get my rocket to around 380. Part of the problem is that I get deployment before Apogee. How are people getting that kind of height with only a 4 second delay? Is there any way to lengthen the delay? Or are we just doing away with ejection and letting them free fall back?
     
  2. Sep 7, 2018 #2

    Charles_McG

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    Estes has an A8-5 - but it's 18mm.
     
  3. Sep 7, 2018 #3

    BEC

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    I'm sure the record holder was piston launched. That gives a speed and effective impulse boost.

    A free fall back would be DQ'd as unsafe.

    It looks like Chad set that record 17 years ago. I wonder if A3-6Ts were still certified then. I have no idea when they went OOP.

    added: Thanks to the catalogs on the Estes web site I've answered my own question. The A3-6Ts disappeared from the catalog on 1985. So they were long decertified by 2001. Oh well...it was a thought.
     
    Last edited: Sep 7, 2018
  4. Sep 7, 2018 #4

    Alan15578

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    Are you including a heavy or bulky altimeter in your sim? What are you assuming for a piston boost?
    I'm not sure when the A3-6t lost its contest certification.

    Yes the A3-4t is too short for some contest flights. I'm hoping the new Estes ownership and management will bring the A3-6t back.

    The 2001 record is still on the NAR website. I would have thought they would have retired the old records that are not relevant to the current competition rules. Just ignore the old record, and compare performance to that of your current competitors efforts.

    You might be able to coast through apogee and use electronic ejection. I think someone did an R&D report on humidity effects of BP motors. They found no significant effect on the thrust portion but high humidity could measurably increase the delay time. So you could keep your motors in a humidor before your contest flight and see if that helps.
     
    Last edited: Sep 8, 2018
    BigRiJoe likes this.
  5. Sep 7, 2018 #5

    BEC

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    Why would they retire the record? Go as high as you can on an A motor is the same now as it was then.

    The category Chad Ring's record is in is for optically tracked flights, not altimeters. Further down in the list is Vern Richardson's C division A altitude with altimeter record, set early last year with an Estes A3-4T and flying an Altus Metrum MicroPeak (which weighs only a couple of grams). Since Vern has done some recent R&D reports on piston launching, you can expect this model was also piston launched.
     
  6. Sep 7, 2018 #6

    BigDuphis

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    I've had pretty good luck with weighing the motors. A lot of times the ones that are slightly heavier tend to have a slightly longer delay on them.
     
  7. Sep 8, 2018 #7

    Alan15578

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    Thanks for pointing that out, and for providing details on the altimeter record flight. I did not scan down the list far enough to find the altimeter record, just the one that Ubersquid referenced, and I noted that it was from 2001. I don't know if Ubersquid is specifically interested in breaking the tracked altitude record. I have not seen any optical tracking set up since the last big competition change. I'd be impressed if Ubersquid could make that happen. The old 2001 record is still valid for what it is.

    In general, the records should not be used as benchmarks for comparing to new designs. One rarely knows anything useful about the record setting rocket. Records are also often flukes of weather, hot motors, measurement anomalies, piston launches, etc. They have become just a way for a rocketeer to get their name on a list, or in a magazine. Back in the golden age of contest rocketry, to get a record certified, the rocketeer had to submit a good photo, drawing, and complete information about the flight. This served to advance the state of the art. The drawings could be published so that others could build a similar model. Modern NAR records are easy, even automatic to get "certified", but they are of questionable value.
     
  8. Sep 8, 2018 #8

    RoyAtl

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    There used to be an A3-6T, but the efficiency of the black powder Estes uses has been going steadily down the past few decades and now a six second delay cannot fit in the 1.75" casing. The last time it was tried (when Ed LaCroix got some A3-6T's made by Estes for the original Apogee back in 1991) the ejection charge was barely contained
     
  9. Sep 8, 2018 #9

    RoyAtl

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    in 1991, Ed LaCroix had Estes make some A3-6T motors for Apogee to sell. They were certified as Apogee motors.

    In the late '90's, Tim Van Milligan's version of Apogee produced a 10.5mm A2 motor. Tim announced the discontinuance of his 10.5mm motors during NARAM 43 in 2001.

    I'd bet that Chad used that motor while it was still certified.
     
  10. Sep 8, 2018 #10

    BEC

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    Roy,

    That makes perfect sense. A long slow burn is generally the way to higher altitudes and an A2 that was a full A or close to it would be ideal. Since Chad has been active in competition for a good long while, I'm sure he'd know about and have access to those motors. I was vaguely aware that there had been an Apogee A2 - but until your post I'd forgotten about them.

    Alan,

    I'm not sure about the "automatic" certification of records. About the only thing that you mentioned in your litany of requirements to authenticate a record that is no longer required is detail about the model's design. I'm in the process of getting a record posted right now - from a flight I made at NARAM-60 - and it's certainly not automatic. But that it took place at NARAM on the contest range, and that data is available to the fellow in charge of records bookkeeping these days did cut down on the documentation I had to supply.
     
  11. Sep 9, 2018 #11

    Rocketjunkie

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    I still have some Apogee B2s :) Apogee B2-2a.jpg

    Apogee B2-3a.JPG
     
  12. Sep 9, 2018 #12

    Alan15578

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    I exaggerated the "automatic", however:
    14.5 Submission
    The Contest Director must review all flight results to determine if any new performance records were set.....

    I neglected mentioning the A2, since I preferred to comment on the need for a longer delay A3t motor that the OP was concerned about. My recollection is that we lost we lost the A3-6t, A3-2t and probably some other motors because some of Estes major customers, big box stores like Walmart, complained that there were too Many motors requiring too many SKUs and display pegs. So to keep customers from asking for motors that they did not display or taking their business elsewhere, Estes was compelled to discontinue some motors. I appreciated the efforts of Apogee to make the classic motors available to competitors. After Apogee started making their own motors, particularly the 10.5mm BP motors, Estes decided to punish Apogee by refusing to sell them the A3-6t and similar motors. Apogee was leveraging the motor manufacturing and licensing of Aerotech in New Mexico to manufacture the A2 and other motors. After Aerotech relocated following their fire, it was no longer practical for Tim to travel to the new location and make Apogee specific motors, and the 10.5mm motors have not been available since that event.

    At some point Estes revealed that the quality of their PB source had declined, and it was no longer possible to produce the A3-6t. I take that just as an excuse. They could always pay more for higher quality materials, or even make their own boutique batches of charcoal, just for the A3-6t. Also, they could have trimmed the delay back just enough to fit, say to 5 or 5.5 seconds. Finally, they could have resorted to the Centuri 2.25" standard 13mm motor length and produced not only the full A3-6t, but the B4 as well.

    I was never a fan or the 10.5mm motors and I never bought any, but is another discussion.

    Recollections and perspectives may vary, but his is mine.

    Alan Jones
     
  13. Sep 10, 2018 #13

    Alan15578

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    oops. Aerotech in Nevada (Las Vegas) not New Mexico.
     
  14. Sep 10, 2018 #14

    UberSquid

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    Thank you for all the responses. This started off as a simple exercise to see how high I could get a small rocket in simulation. It's been a long time since I've built a small rocket that could be fired locally so I was considering making a few park fliers. Once I started down that path, I stared wondering just how high one could go on an A motor. That is why I looked up the records. I've simed everything from bare single stage to piston launch multi stage and the delay issue kept coming back. Just made me wonder how others were addressing it. I guess this answers my question. I'll start trollilng ebay and closeout sales to see if I can find some long delay motors.
     
  15. Sep 10, 2018 #15

    BEC

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    And of course now Aerotech is in Utah.... :)

    It will be interesting to see what direction Estes Industries goes in with the new president of the company having been involved in competition quite a bit when he was younger (and his Dad still is involved with the FAI teams). We shall see....

    Much of that history you recounted I have heard about but it all occurred in the three decades I was not actively involved in model rocketry.
     
  16. Sep 10, 2018 #16

    Steve Shannon

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    You can click on your original post and choose edit to correct it.
     
  17. Sep 11, 2018 #17

    RoyAtl

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    That is correct.
    Actually Estes (either Buroker or Barry Tunick) declined to make more motors for Apogee when Ed LaCroix became one of the group that started Quest (of course the question I've never asked Ed, was whether he was going to make another order in the first place). It was the original batch of motors that had the 'filled to the brim' A3-6Ts. Ed was already making his small B8 and C10 composite motors at Aerotech even when he was still based in Minnesota.

    Ed later sold Apogee to Tim Van Milligan (who had just left Estes), and almost certainly Barry wasn't going to sell a batch to Tim.

    The general understanding was that Tim was making these motors in small batches by hand to a European recipe. It was unclear why he suddenly stopped making them in 2001, but scuttlebutt at NARAM that year said he had a "close call accident" and decided the risk was not worth it. Hard to think there would have been licensing issues since they'd been on the market for nearly five years. If he was making them at Aerotech, the move after the Las Vegas fire would have been to his advantage, with Cedar City being almost 200 miles closer to Colorado Springs.

    It is possible that the Langfords might throw some money, or at least some experiments, at this to see if they can improve quality, but I'm doubtful. Also, you do know about "Estes Time", don't you? I.e. Estes delays already usually run a 1/2 second or so short.

    And immediately consign dozens of thousands of existing rockets to the dustbin, and redesign the complete line of mini rockets? Not very likely.
     
  18. Sep 11, 2018 #18

    Alan15578

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    I don't think TVM ever made his motors in Utah, but it would be nice if he did.
    I don't want to try telling the Langfords how to run Estes. But my guess would be to first rebuild supply chains, and get or keep things running in the black, then look into marketing dream and legacy motors.
     
  19. Sep 11, 2018 #19

    Alan15578

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    Thanks for filling in the gaps and making some corrections.

    To clarify, I did not mean to imply that TVM had licencing issues with with his motors. Rather, he made motors at Aerotech, because they had all the explosive usage and manufacturing permits, etc. On the map, the Utah facility is actually closer. You would have to ask TVM why he never resumed production of his motors at the Utah facility. My guess would be that flying into Las Vegas is very cheap, and makes for a good family trip. He may have just been tired of making motors, and it was no longer "fun" to brave the inherent risks.

    I know that Estes delays typically run short of the number on the motor label, but the total impulse also runs short of their published catalog values. So if a customer does performance prediction based on catalog data, they will still most likely end up selecting a motor for a safe flight. I always use certification numbers, but that info was not always available.
     
  20. Sep 11, 2018 #20

    RoyAtl

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    good point. Either way, he probably has to ship the final products back to Colorado Springs. As we learned on the Estes tour, manufacturers have special restrictions and they have to have special licensing just to drive motors from manufacturing across the street to warehousing!
     

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