L3 electronics/recovery

Discussion in 'High Power Rocketry (HPR)' started by Ben Martin, Feb 12, 2019.

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  1. Feb 12, 2019 #1

    Ben Martin

    Ben Martin

    Ben Martin

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    I have been planning out my Performer 98's recovery system with electronics and wanted to get some feedback/tips from the community. The whole goal of this project is to get more experience in L2 and go for my L3 on a college budget once I am ready. Total price for this project including motor should be under $1000.

    I'm using RocketPoxy for constructing the rocket and will be notching the top centering ring for the y-harness to pass through.



    Recovery:

    MAIN: PAR-70 w/ SW-1500 protected by 12" x 12" nomex attached on midline loop
    (Payload bay)

    DROGUE: PAR-18 w/ SW-1500 protected by 12" x 12" nomex attached on midline loop.
    (Booster section)

    SHOCKCORD: 1/4" tubular kevlar
    - 15ft for booster, 15ft for payload, 9ft y-harness glued onto motor tube (around 3ft on each side) and attached to the booster shock cord with quick link.

    Simulation: ~80fps on PAR-18, ~16fps on PAR-70



    Electronics:

    - RRC3 Sport (main) deploy drogue at apogee and main at 800ft.

    - RRC2+ (secondary) deploy drogue at apogee +1 and main at 500ft.

    - RRC3 Dual 98mm Modular Sled System (2 switches, 4 bulkhead terminals, 2 snaps) just need wiring kit suggestions.



    Tracker:

    Need suggestions for around $200, will probably end up being in the nosecone (Ebay) or in a bay attached to the nosecone bulkhead ubolt.



    Suggestions/tips regarding any part of the project are appreciated. The initial simulations show the rocket reaching 14K ft at Mach 1.4 on an 'M' motor, but of course that will change as the project progresses and I complete 3 or more shakedown flights.


    IMG_20190209_192822.jpeg
     
  2. Feb 12, 2019 #2

    Ben Martin

    Ben Martin

    Ben Martin

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    I will be posting the initial simulation file tomorrow but it lacks a lot of details.
     
  3. Feb 12, 2019 #3

    ECayemberg

    ECayemberg

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    Hi Ben,

    The Performer 98 looks like a good candidate for more L2 practice and an L3 shot when ready! I did my L3 on a very similar airframe a few years back (4" rocket, 3" hole, Curtis glass).

    My suggestions are just that, suggestions! Here they are:

    -15' of shockcord on the booster: Go longer! 30'+ for sure. Necessary, maybe not, but longer tends to be a bit more forgiving for less-than-perfect deployments or less-than ideal wind conditions. 15' is fine for the main where the forces are generally lower.

    -Main chute: hold off on that one until you're farther along in the build...to get a more accurate weight of the rocket. A 70" will work, but if you're looking for the "standard" ~20 feet per second descent rate under main, you may want to upsize a tick. I fly a Top Flight 84" as the main in my 4" glass rockets.

    -Nomex size: I typically see the recommended sizes as 3 times the diameter of the airframe tube...this works great in most cases. I'd personally upsize the main protector. Again, personal preference, but while I don't use chute deployment bags, I do "burrito wrap" my main chute in a large protector. An 18" x 18" protector will do a good job of this in a 4" airframe; a 12" x 12" wouldn't cover a 70"-84" chute well enough for my tastes anyway.

    -Practice: NOT A LECTURE, simply agreeing with your idea to get some practice in before trying the L3. Take your time and enjoy the hobby! Many people that rush through the levels are 1,2,3 and out of the hobby; stick around for a while! Most TAP's will note that you did L1 and L2 two or three months back and will say you're not ready for L3 yet. I'm not saying that one way or another; just saying enjoy the build, document it, get in a few flights and take it from there! As I mentioned, I did my L3 "on a budget" while in college with a 4" glass bird in 2005. Gosh, I'm gettin' old! Anyway, I had 4 or 5 years of L1 and L2 flights in before tackling it....your mileage may vary.

    Cheers!
     
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  4. Feb 12, 2019 #4

    Steve Shannon

    Steve Shannon

    Steve Shannon

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    Everything Eric said is correct, but I would go further and tell you that a build thread on TRF is no substitute for working directly with a TAP or L3CC member.
     
  5. Feb 12, 2019 #5

    Jim Hinton

    Jim Hinton

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    Amen to Steve's sentiment about advice from the experienced. My L3CC, Mark Lionberger has been of invaluable assistance. Including but not limited to, making me do all of the L3 paperwork items that I really don't like. That paperwork pays dividends as the project progresses.

    Jim
     
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  6. Feb 12, 2019 #6

    Bat-mite

    Bat-mite

    Bat-mite

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    My suggestions:

    Wiring kit: Doghouse Rocketry, a division of Binder Design

    Tracker: assuming you don't have a ham radio license, that rules out anything but 900MHz or Blue Tooth. If you can scrape up another $100, I recommend the BRB900 from Big Red Bee. It comes preprogrammed and ready to use. Just turn on the Tx, stick it in the rocket, turn on the Rx, and go launch. You will also need some sort of navigator to walk you to the rocket. You can get cheap, old hiking GPS handhelds for about $25 on ebay.

    The EggFinder is much less expensive, but you need to solder the kit together. This means you also need a good soldering rig, and those aren't cheap. Or, pay someone to solder it for you.

    If you get cellular service at your site, there are Blue Tooth trackers out there that send coordinates to your phone.
     
  7. Feb 12, 2019 #7

    JDcluster

    JDcluster

    JDcluster

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    I think the 1/4" tubular Kevlar is a little on the small side. I usually use 9/16" TN or 3/8 tubular Kevlar for this sized rocket.
     
  8. Feb 12, 2019 #8

    Nytrunner

    Nytrunner

    Nytrunner

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    Looks like a DX3 XL, should be a good project! 35 lb DX3 XL goes 10k+ on the baby M1297

    I concur with the 9/16 tubular nylon suggested above. A nomex cord protector or ductape strip will protect it from charges just fine.
    Alternate suggestion: 75 and 98mm motors have a threaded forward closure. Stick a forged eyebolt on there and you've got the strongest shock cord mount around.

    for the tracker, Missileworks T3 is a paired 900 band receiver and transmitter for ~150. Just need a couple Lipo's and an android device to run rocket locator and you're good to go. (folks with iphones have gotten a cheap android tablet w/ bluetooth to run the app. Even gives you a bigger screen that way :) )
     
  9. Feb 12, 2019 #9

    ericm541

    ericm541

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    I would go up on the kevlar, that's my personal preference though, how much do you think it will weigh? Since your planing on L3 i would document the construction and more importantly contact L3CC or TAP. If you're doing NAR L3 cert you must submit detailed plans for review and approval prior to the start of construction. Looks as though your heading in the right direction as far as preparation.
     
  10. Feb 12, 2019 #10

    Ben Martin

    Ben Martin

    Ben Martin

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    I am working with a TAP member at my local club.
     
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  11. Feb 12, 2019 #11

    Ben Martin

    Ben Martin

    Ben Martin

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    Thank you for your input! I'll definitely make the shock cord longer as it is kevlar and not nylon so it won't absorb much shock. Bigger parachute protectors sounds like a good idea that I will go with. For the parachute I will hold off until the rest of the build is done.

    I definitely am going to get experience before I even think about sending it up in on an M. I am in contact with over half a dozen L3 members at a local club whom are more than willing to help out.
     
  12. Feb 12, 2019 #12

    Ben Martin

    Ben Martin

    Ben Martin

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    I would likely have to launch it at an event such as LRDS so cellular service is not a guarantee. The EggFinder looks like a solid choice if I use a soldering service, certainly need a tracker because who knows where it is going to end up after drifting. Thank you for the solid suggestions, that wiring kit looks like a winner.
     
  13. Feb 12, 2019 #13

    Ben Martin

    Ben Martin

    Ben Martin

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    The threaded closure suggestion would make my life a lot easier but many of the smaller motors I plan on testing it on won't have that option, hence why I am going with the more complex y-harness. I'm going with kevlar as it is more forgiving to ejection charges and with an increased length it should absorb shock too.

    T3 looks like a good option, I will look more into it. Don't want to lose my flying college loan.
     
  14. Feb 12, 2019 #14

    Ben Martin

    Ben Martin

    Ben Martin

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    I was told to make sure to document it, so I will be recording the build process with a GoPro and taking photos along the way. It will be a fun project, I am looking forward to getting started.
     
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  15. Feb 12, 2019 #15

    Steve Shannon

    Steve Shannon

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    Perfect! I will enjoy reading your build thread.
     
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