Chute release alternative

Discussion in 'Rocketry Electronics and Software' started by jdbwizzard, Dec 16, 2016.

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  1. Dec 16, 2016 #1

    jdbwizzard

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    Has anyone ever attempted to make there own chute release?

    I have been working on my own arduino altimeter with great success. This got me thing of putting the same tech into a chute release. Logging flight data plus the chute release.
     
  2. Dec 16, 2016 #2

    Charles_McG

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  3. Dec 17, 2016 #3

    jdbwizzard

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  4. Dec 17, 2016 #4

    Charles_McG

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    I was advised (by Eggtimer Cris) that rubber bands are actually very hard to cut reliably with a hot wire.
     
  5. Dec 17, 2016 #5

    burkefj

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    Tom Blakeney has been doing an RC based system with good success..
     
  6. Dec 17, 2016 #6

    sl98

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  7. Dec 17, 2016 #7

    Buckeye

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    Over the years, I tinkered with my own fishing line cutters, cable cutters, and rubber band releasers. They were too much trouble/unreliable for me, so I went back to traditional two-tube DD.

    The beauty of the JLCR is that it is non-pyro, self-contained, and so simple. I would not consider anything needing an ematch or heating element to be an equivalent alternative, though.

    View attachment 307509 View attachment 307510
     
  8. Dec 17, 2016 #8

    tab28682

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    I am pretty happy with my RC Chute Sled. It is also non-pyro, self contained except for the RC transmitter and dead simple to use. I do not seeing flying any future mid or high power rocket that is likely to remain visible during the flight without one.

    I really like the ability to pick the release altitude on demand. On one flight, the rocket weathercocked a bit and was well upwind when it ejected. Let the separated rocket fall for a while to estimate drift. It was going to be well upwind for a low altitude release, so I deployed at a much higher altitude than normal, about 600-700 feet. The rocket landed less that 100 yards upwind.

    Alternatively, on a flight on windy days when the separated rocket drifts downwind during the fall from apogee, I can delay the opening of the main until as low as is practical.

    For flights that are likely to need tracking devices and go out of sight, I am planning on using the JL CR in series with my RC Chute Sled for the best of both worlds.

    Cost is very low. I can build 3-6 RC Chute Sleds (cost depend on component selection of receiver, sero and the one cell lipo battery) for the cost of a JL CR, given that I already have the RC transmitter.

    The average rocketeer is not as comfortable with RC as they are with more traditional methods of recovery and usually lacks the transmitter.
     
  9. Dec 17, 2016 #9

    cerving

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    The Eggtimer Classic and Eggtimer Quantum will operate servos natively, i.e. with no additional circuitry (other than one resistor, for continuity). There have been a few people that have used them similarly to a JL CR, the trick isn't the electronics, it's the mechanical part. John Beans did an excellent job with the CR...it's convenient, easy to use, and very reliable.
     
  10. Dec 17, 2016 #10

    Winston

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    Yes, on and off, mostly off, for multiple years, but it is only microcontroller timer based which gets me most of what I want - zipper prevention. However, longer delays can bring it down from altitude before opening the 'chute if one is conservative with delay times until the descent rate of a particular rocket model with a reefed 'chute is approximately known. My thread on this:

    http://www.rocketryforum.com/showthread.php?133342-(Chute)-Reefer-Madness

    I've gone through multiple fishing line non-contact thermal cutting techniques (opposing glow plugs, vape heater, most recently a tiny TO-18 300mW 808nm (near IR) laser diode (only $3 each)), all unacceptable to me for one reason or another. I have a functional (ground tests only) one based upon a linear micro-servo and latching method (the one with the 3D printed case in the above thread), but it's larger than I want. I'm currently waiting for parts for another method which I suspect will be best and smaller. None of my methods use any pyrotechnics at all which is the goal.
     
  11. Dec 17, 2016 #11

    jdbwizzard

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    Thanks everyone for the insight. I figured I would give it a go with the components coming in at under $10 for my design. If I have any success I will share what I did but it doesn't look to promising at this point.
     
  12. Dec 18, 2016 #12

    fulldec

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    Alyssa Stenberg did an R&D report on an RC Alternative to the Jolly Logic Chute Release. She developed 2 very clean designs that performed well in testing. The report is available to NAR members on the R&D Report Website under NARAM-58.

    Don
     
  13. Dec 18, 2016 #13

    Winston

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    I plan to share everything, too, once carefully tested. I'm looking forward to your info, too. I believe the following: "Steal from the best" and "If I have seen further it is by standing on the shoulders of giants." If not "giants," at least people who are "taller" than me. I don't know how many times I've thought, "Now, why in the heck didn't I think of that?"
     
  14. Dec 18, 2016 #14

    dhbarr

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    Humble pitch for keeping two of the dimensions inside an 18mm ( or better, 13mm! ) coupler. I know, I know.... but an a10 rack rocket with 2-stage recovery just cries out to be made!
     
  15. Dec 18, 2016 #15

    jdbwizzard

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    I have plans for a tiny device. I'm waiting on some components right now to come in the mail. 13mm might be a stretch but I think 18mm is doable. I will find out soon enough. I'm switching from arduino to attiny85.
     
  16. Dec 18, 2016 #16

    dhbarr

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    Right now the smallest true DD I can do is a Bear AltiDuo SMT w/ Prairie Twister cutter. Not terrible, but I'd love something more elegant.
     
  17. Dec 19, 2016 #17

    Winston

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    Eager to see your results. What limits the low end of size in all of my designs thus far is a servo-mechanical or thermal cutting initiation of 'chute deployment that doesn't require replacement between flights or any wiring external to the device in the pursuit of reliability.
     
  18. Dec 19, 2016 #18

    burkefj

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  19. Dec 19, 2016 #19

    Winston

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    I like the R/C idea, I own multiple R/C TXs, one of which is modulation compatible with this RX which can operate using a 1 cell lipo:

    FrSky VD5M 2.4Ghz 5CH Micro Receiver - $11

    https://hobbyking.com/en_us/frsky-vd5m-2-4ghz-5ch-micro-receiver-telemetry-capable.html

    However, most people don't own a R/C TX I suspect. Although low end TXs certainly aren't expensive these days,:

    Turnigy 5X 5Ch Mini Transmitter and Receiver (Mode 2) - $25

    https://hobbyking.com/en_us/turnigy-5x-5ch-mini-transmitter-and-receiver-mode-2.html

    such systems usually don't have removable antennas with SMA connectors and for my piece of mind for possible range considerations with such low end systems, I'd want to attach one of the cheap aftermarket patch antennas with higher gain made for R/C TXs and in the case of those cheap TXs, attachment would require a fairly simple, physical hardware mod which might thereby technically violate FCC TX certification rules.

    This is why my system has always been aimed at autonomous operation, depending upon the darkness in the 'chute bay for arming and the illumination once ejected to start the unreefing countdown. However, my current method will always require SMT soldering onto either a home etched PCB or a commercially made PCB, so it definitely has its major disadvantages.

    That's why I definitely DO like the off-the-shelf R/C TX initiated systems as long as potential range issues can be addressed with cheap hardware without violating FCC rules and if the need to have the rocket in sight to remotely trigger unreefing isn't an issue. Some kind of default timeout for 'chute unreefing on R/C controlled systems would be great and could be provided if an external microcontroller was included along with R/C RX. If the R/C unreefing system uses thermal cutting and not a servo which requires a PWM signal, a simple monostable multivibrator circuit could be used for the backup time-out delay.
     
    Last edited: Dec 19, 2016
  20. Dec 19, 2016 #20

    burkefj

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    Interesting point about the range, I guess if you are under 1K you probably have no issue, if the system is set up to not release when it re-binds, if you lose link, you should be able to gain it back around 1K distance and you aren't going to deploy till 500' most likely, assuming it drops fairly straight, but probably limited to lower flights unless you can boost things...

    Frank
     
  21. Dec 19, 2016 #21

    tab28682

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    I am using an AR400 Spectrum full range RX in the larger version of the RC Chute Sled and I have tested it in excess of 4000 feet slant range. Even with the Lemon RX unit with the short antenna used in most of the G powered flights tested out to well over 1000 feet slant range. Probably had at least another 1000 feet in it. Frank's range comments are correct. Even if it does go out if range, it will very likely come back into range on the way down.

    The proof is in the results. Seven G powered flights and one I powered flight and the release has worked every single time.

    Am going to fly the Spectrum telemetry unit in the next high power flight and check the number of of lost frames and fades in the signal. I predict they will be near nothing, comparable to what you get flying an RC aircraft.
     
  22. Dec 19, 2016 #22

    Oberon

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    Wouldn't the bigger concern with an RC based system be losing sight of the rocket? Certainly at our field there are at least one or two flights a day that get lost until fairly late in the descent - in fact often it's main deployment that makes the rocket visible again! So that's a potentially unsafe failure mode that the Chute Release or autonomous alternative doesn't have.
     
  23. Dec 19, 2016 #23

    soopirV

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    I had a similar thought...but no experience. I HAVE had a flight where I wish I had a much larger ejection charge wired to a manual R/C control when my charge failed to separate...hit a button and BOOM, drive the tubes apart in an emergency. Someone makes that, can't remember who...Pratt?
     
  24. Dec 19, 2016 #24

    tab28682

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    The models I am flying so far have and will stay in sight. If visibility is poor, we can go another way. Any higher flights with these models will get a silver Mylar streamer at motor or apogee ejection that will help pick it up again. If I do not have sight of the model after a few seconds into the chute-less decent, I will pop the chute earlier.

    I do not see any risk for the RC Chute Sled being any higher than the possibility that a altimeter based ejection system failing to open a main or a motor ejection only failing. The models are coming down are separated with the fin can and payload section connected by a shock cord. Mine are falling slow enough that a touchdown without chute is unlikely to do much damage.

    Adding a drogue chute also mitigates issues of landing without a main.

    As mentioned earlier in the thread, higher altitude flights more likely to go out of sight will get a main chute with series setup of a JLCR and the RC Chute Sled so that either can do the trick when needed.

    There is no one perfect recovery system for all occasions. This particular setup is working well for me (perfectly so far) for the type of rockets I usually fly: mid power and L1 high power models of 2.6" - 4" diameter. I know it can be thoughtfully used for lots of other situations.
     
    Last edited: Dec 19, 2016
  25. Dec 19, 2016 #25

    tab28682

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    Yes, Doug Pratt had one.

    I have a couple of projects in mind that are likely to get an RC activated backup ejection system.

    Modern programmable RC transmitters have some great switch mixing capabilities. I have been doing rocket motor air starts on RC rocket gliders where you have to flip a toggle to arm the circuit before hitting the ignition switch, using a programmed switch setup on my TX (Spectrum DX9). This would work well for backup ejection of a model within eyesight range.
     
  26. Dec 20, 2016 #26

    burkefj

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    I had one of the pratt systems in the 90's, it never ever worked in flight for me...the one time it worked was when I walked up to the darn thing on the ground and pushed the button standing right next to it....these were in cardboard rockets so attenuation should not have been an issue...

    Frank
     
  27. Dec 20, 2016 #27

    Winston

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    That was, as I stated, my concern, too, along with a potential range issue for those who don't already have a quality R/C TX and buy a cheap one just for rocketry use. Higher gain antennas like patch antennas could be easily used on the quality TXs which typically have their antennas attached via a screw-on/off SMA connector, but a simple and perhaps FCC rule violating mod would be needed with the cheap ones to attach that type of antenna.

    Still, I really like the R/C deployment idea and perhaps further real world experience with them, especially using cheap TX units, may prove those concerns to be baseless.
     
  28. Dec 20, 2016 #28

    cerving

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    That's kinda why I put the "failsafe" feature in the Eggtimer Quantum... it attempts to detect when your drogue isn't working and fires the main. I personally fly a lot of small rockets that go out of sight, and I don't always get a visual under main. That's what GPS tracking is for... :)
     
  29. Dec 20, 2016 #29

    Winston

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    I found a very popular low cost TX with an SMA connected external antenna to allow easy connection of a higher gain (directional) patch or helical antenna:

    Turnigy 6X FHSS 2.4ghz, range test



    In that test of the 6X a 760 meters range was achieved - approximately 5 feet to 5 feet above the ground, but near water and over wet sand (at depth) - airborne range should be considerably greater even without a directional antenna. I'd guess the 6XS (6X with more features) which has an SMA connected antenna plus an LCD status display should provide the same stock range as the 6X.

    Turnigy 6XS FHSS 2.4ghz Transmitter and Receiver (Mode 2) - $46.67 + $18.21 shipping from China

    https://hobbyking.com/en_us/turnigy-6x-fhss-2-4ghz-transmitter-and-receiver-mode-2.html

    Transmitter Turnigy 6XS - Introduction and look outside and inside

     
  30. Dec 20, 2016 #30

    Winston

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    Yeah, that failsafe is handy to have. My goal has always been non-pyrotechnic release of 'chute reefing ever since the apparently not very reliable and very expensive Chute Tamer device appeared and gave me the idea of a much smaller DIY unit:

    http://www.rocketryforum.com/showthread.php?108345-Chute-Tamer-Good-idea

    My project subdirectory earliest file dates indicate that I began to work on that DIY idea on and off (MOSTLY OFF) in the summer of 2013 even though that Chute Tamer thread is from summer 2007!
     

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