Small Format Staging Electronics

Discussion in 'Rocketry Electronics and Software' started by Homer_S, Dec 13, 2019.

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  1. Dec 13, 2019 #1

    Homer_S

    Homer_S

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    I'm already a huge Chute Release fan but I'm edging my toes towards traditional dual-deployment. I thought I would start with a small two-stage rocket with an air start. The small format staging stuff I have found (aka PerfectFlite miniTimer4) are OOP either permanently or temporarily. Is there a current one out there? I found the Apogee SimpleTimer, but I'm hoping for an acceleration based one rather than timing. Also, $85 seems steep for a single function.

    Homer
     
  2. Dec 13, 2019 #2

    rharshberger

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    how small are you looking for, as in to fit what size airframes?
     
  3. Dec 13, 2019 #3

    heada

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  4. Dec 13, 2019 #4

    rharshberger

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  5. Dec 13, 2019 #5

    Homer_S

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    It is the printed inter-stage for this kit. It fits into a 29mm tube, so just under that size. The PDF instructions show a miniTimer4. Not positive that is totally to scale.

    Homer
     
  6. Dec 13, 2019 #6

    timbucktoo

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    Minitimers are still available. They sell out quick. I just bought one a few weeks ago. Check his website often.
     
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  7. Dec 13, 2019 #7

    markg

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  8. Dec 13, 2019 #8

    solid_fuel

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    The bullet points for the kit on the link you posted state:

    Uses PerfectFlight microTimer2 or miniTimer4 (not included)
     
  9. Dec 13, 2019 #9

    Ez2cDave

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  10. Dec 13, 2019 #10

    heada

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    You're right, I was thinking recovery. Quantum can do both, act like a timer with safety lock-outs as well as recovery. It's still small but I don't remember if it'll fit in a 24mm tube.
     
  11. Dec 13, 2019 #11

    rharshberger

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  12. Dec 13, 2019 #12

    FredT

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  13. Dec 14, 2019 #13

    gtg738w

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    Just curious what motor/igniter you’re trying to start. Are you looking for something that also has outputs for separation and deployment or just staging?
     
  14. Dec 15, 2019 #14

    Homer_S

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    Just sustainer ignition of an Estes BP 24mm motor for now. The instructions for that kit want you to put a water-soaked, expendable, disc in the inter-stage.

    Homer
     
  15. Dec 15, 2019 #15

    Andrew_ASC

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    Dude you can gap stage a Estes black powder motor like an E12-0 booster tumble recovery directly to a E-12-6 on sustainer. The ejection charge of -0 ignies the upper stage Estes motor. Look up Estes extreme 12 etc. And best part is no electronics needed there.

    I’ve worked with six multistage hpr rockets using 29 and 38mm APCP H and I class motors some won national comps for multistage flights at university levels. For those kinds of builds nothing matches the ease of programming and ground testing of raven units. You’ll want to try the velocity and time check functions on it to limit the angle the rocket sustainer igniter can ignite at. There’s even advice on supersonic staging in their manuals which is invaluable.

    Then you can program the parachute deploy settings on a Raven so that chute deploys with separate bp charge and electronic igniter even if sustainer motor fails to ignite and fails to ignite motor delay. Much safer than a straight up timer and I’ll credit one to saving lives.

    Let’s say you only had a timer and it ignites the igniter of sustainer stage but the motor propellant does not have ignition success. Your motor deploy ejection charge of the sustainer will fail. It will come crashing in ballistic without a separate electronic altimeter that fires pyro charges for recovery of sustainer without needing motor deploy. (The raven unit has additional channels to fire more igniters to deploy a chute after the motor either lights or doesn’t light.)

    The other really horrific failure method of timer only is if sustainer stage tilts in flight let’s say it weather cocks unexpected on boost after first stage separation. The timer reaches said time and dumbly fires the sustainer stage motor igniter. And it doesn’t care what orientation the rocket is at. The weather channel has a horrific accident where a multistage Hpr timer only flight ignited badly which I used to enforce to new students why we should just use a raven or other altimeter based system with some kind of tilt check. I’ll try to link it if I find it again.

    They don’t even force you to use a tilt check system but I find it superior safety wise to set it up especially for apcp motors extremely especially if high power motors. If this is first multistage with bp only motors I suggest you try gap staging to other bp motor instead as it’s much simpler. If your wanting to light APCP motors get a Raven, Marsa, or Telemetrum unit that affords you some additional tilt safety.

    I’ve also found most HPR sites dislike anything timer stages only and for good reason.
     
    Last edited: Dec 15, 2019
  16. Dec 15, 2019 #16

    Andrew_ASC

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  17. Dec 15, 2019 #17

    Andrew_ASC

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    One of the projects I was involved on last year as a student. Two H’s in 29mm MD. We used a raven for safety reasons. It did 11,563 ft and 1303 mph. Another university group this year did 18,700 ft.



    Anyways just to give you an idea on staging.
     
  18. Dec 16, 2019 #18

    Homer_S

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    Thanks!

    I've gap staged 8" or so before. This one is a little over 9 1/2" going from four motors to one. Also, the inter-stage is already printed. I suppose I could draw it and have it reprinted. Instead of that, I want to go the electronics route. This will help me gain knowledge and confidence on my journey to L3.

    Homer
     
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  19. Dec 16, 2019 #19

    Homer_S

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    Someone might have noticed... I now have a miniTimer 4 on order! Next up, a battery and wiring. I'm thinking of these: batteries and charger.

    Homer
     
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  20. Dec 16, 2019 #20

    rharshberger

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    The batteries are Hobbykings Turnigy Nano-Tech, I like them, however check Hobbykings actual website you may be able to save some money buying direct from them instead of through Amazon.
     
  21. Dec 16, 2019 #21

    timbucktoo

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  22. Dec 16, 2019 #22

    Homer_S

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    Thinking about this... the timer is no worse in this application than gap staging. At least the timer has to have left the pad when it is set for delay after burnout.

    Homer
     
  23. Dec 18, 2019 #23

    Homer_S

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    Thanks everyone for your input! Last thought on timers: if you could stage the motors directly or with a gap, a timer is not an increased risk.

    On wiring the eMatch, timer and battery. Would these be two be connectable (battery and connectors 1) or do i need this one for the battery (connectors 2)?

    Homer
     
  24. Dec 19, 2019 #24

    wrad

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    Small format electronic staging rely is a big challenge, much more challenging than dual deployment in a medium sized rocket. I love egg timer quantum’s but as you say probably only space for a timer in that kit which is fine for low power staging, if you are moving towards dual deploy/ more electronic staging the quantum is a great choice or the photon or raven which others have mentioned for a bit more cost but loads of functionality.
     

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