L2 Recovery Options

Discussion in 'High Power Rocketry (HPR)' started by Mike Haberer, Nov 25, 2019.

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  1. Dec 10, 2019 #31

    Andrew_ASC

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    Already got L1 I kept it low, slow, and dumb for L1. For L2 I want to advance my knowledge of dual deploy and electronic tracking. I actually plan on flying it on a J250W DMS for cert to keep it subsonic and below a waiver about 2,500ft lower than a waiver at the lowest FAA ceiling I got access too. And I started learning hpr on multistage Min diameter long ago while in university. I think I got this. There’s been a lot of good advice here. I appreciate your advice. Finances is not an issue sitting on $3.8k right now with all bills paid.

    This route is not for faint of heart or wallet and I understand any cert attempt can fail. I already had the ham ticket and electronics. Beyond a half mile up I feel electronics is key for tracking rockets.

    Ironically my professor went with a large heavy dumb rocket on a J350W and he was beyond pissed when an aerotech motor delay failed.
     
  2. Dec 12, 2019 #32

    rewilfert

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    Here's some data for you. I did my L1 and L2 on a fiberglass Super DX3. It weighed just over 11 lbs sitting on the pad. I flew it with a I284W on my L1 attempt to 1198 ft and a J420R on my L2 attempt to 1766 ft. Both flights used motor ejection and a JLCR for dual deployment. I used a Jolly Logic Altimeter 3 to record the flight data. With 10 second ejection delays on both flights, the motor eject separated the rocket within 10 ft of apogee. With no drogue, it came down from apogee at 67 fps on my L1 and 79 fps on my L2 until the JLCR popped the main. In both cases, it took about 125 ft from the time the chute release let go (set at 700 ft) until the main was open. Landing speed was right at 20 fps in both cases.

    Using motor eject and a JLCR was a nice easy way to get the certification flights completed. I had everything available to me to do full electronic dual deploy. I just decided for these flights, keeping it simple was the way to go.
     
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  3. Dec 12, 2019 #33

    John Taylor

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    I'm set for my level two flight Saturday. Aced the test last Sunday and I'm bout ready. Was planning to Fly my 7lb 4" dia. 7' tall rocket on a J250 with 10sec motor ejection delay, then a JLCR for main opening. Now I've heard the wind is forecasted at only 6mph all day! Now I'm considering just blowing out the main at Apogee 2500'. With that light wind it shouldn't go too far. Just to keep it as simple as possible.
    What to y'all think???
    Thanks.
     
  4. Dec 12, 2019 #34

    Nytrunner

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    Depends. How far do you want to walk?
     
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  5. Dec 12, 2019 #35

    John Taylor

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    As long as I don't actually lose it I guess not over a mile or so, all the landowners around our site are rocket friendly. I would rather walk some than to have the chute not open properly for whatever reason keeping me from getting my certification. 6mph wind is a rare occurrence in north Texas. I believe it will stay relatively close. Please let me know what y'all think.
     
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  6. Dec 12, 2019 #36

    John Taylor

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    If the forecast is not correct regarding the wind speed, I can go back to using the chute release.
     
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  7. Dec 12, 2019 #37

    richP

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    There can be, and usually is a huge difference between the wind on the ground, and what's happening at 2500'.
     
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  8. Dec 12, 2019 #38

    rewilfert

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    The last high power launch I was at, there were over 14 L1 cert flights. Winds were generally <5mph all day. A majority of the people simply put the chute out at apogee. In low winds, how far you have to walk depends a lot on the trajectory of the rocket.

    Not using a JLCR takes one variable out of the equation. It really depends on how big your recovery area is and what obstacles (trees?) are in the area.
     
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  9. Dec 12, 2019 #39

    boatgeek

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    Don't be the first to launch that day. Check out another flight to the same-ish altitude and see if you want to walk as far as it goes. :) Also, look for trees in the LZ. All trees are rocket-eating trees.

    If the winds are favorable, I might not use a CR, particularly if you don't have a lot of experience packing them. One fewer points of potential failure.
     
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  10. Dec 12, 2019 #40

    John Taylor

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    Right, I calculated 1126' drift distance @ 6mph and 20'per second fall speed that's 128 seconds falling at 8.8' per second lateral distance. Now of course I have no idea what the aloft winds are doing. Correct on watching other flights first.
     
  11. Dec 12, 2019 #41

    John Taylor

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    The chute release is new. I have been practicing folding the chute according to the site instructions and have done tests with packed chutes in my living room. I have been packing the chute and flying several rockets on motor deployment and they all opened quickly no problem. I have read all I can in here about people's experiences with the JLCR. I plan to fly a couple of other flights before the cert flight using the chute release to verify.
    Still with so much riding on getting my cert, I am a little wary.
     
  12. Dec 13, 2019 #42

    Andrew_ASC

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    I’ve flown a Wildman RB-05A scale missile quite a bit in the 2200-2500ft range on a variety of H motors from the AT H123 to mainly the H130W it’s about 3.3 pounds loaded and lands at a standard descent rate of 25 fps. Motor deploy and pop chute (24” iris drogue) at apogee. Very stumpy short rocket without a lot of room for a JLCR or dual deploy. It’s completely visible with chute popping at apogee. I’d guess it drifts typically 1/8-1/4 of a mile on under ten mph winds. If your launch site has large field like a mile in all directions and not many trees I’d say you’d be fine. Make sure you don’t have like gulleys or cornstalks obstructing your line or sight when it lands. With visual recovery don’t fart around with watching other flights. Get a visual line referenced out at distance to where your rocket landed then just walk a straight line. I might be beating a dead horse but it’s doable. Launch rod angle and winds are critical along with size of field for motor eject single deploy to be effective.

    Don’t send this or any single deploy setup like a mile plus up without a tracker and expect to get it back. Why a lot of people bad mouth this is a new guy may push 3k ft on a windy day with a light modded Estes rocket and it’ll just drift way off the field to never be seen again. I’d say if your at or below 2.5k ft with big field you’ll be fine. As much praise I’ve seen JLCR get I’ve witnessed one fail and I personally decided to not use it.

    I like the prep simplicity of single deploy motor eject a lot. There’s a lot less you can do to foul it up on ground before flight. Just pack it and light the motor. There is more weather dependency and field size/terrain dependency as to you recovering the rocket as planned. Anyways I just wanted to get you some harder realistic data in this approach.

    It’s not as recommended as dual deploy or JLCR due to large drifts. I’ve even done single deploy multi stages to 11,500ft for competition it saves us weight. But at that extreme altitude the drift went to 1.4 miles on a calm day and well simply put when I bought a L2 rocket I decided to go dual deploy after learning swamp recoveries just suck. Maybe I ranted to much just trying to get you some expectations of wind drift on single deploy at apogee.
     
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  13. Dec 13, 2019 #43

    Andrew_ASC

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    I think your flight profile will work fine for single deploy at apogee without chute release. I’ve done this single deploy apogee stuff before and I’d totally fly your rocket in such configuration. I basically had the same concerns as you about a JLCR unit failing. However unlikely they are to fail I have witnessed failures and seen rockets get nosecones crunched on ballistic entry. The JLCR user was being extremely cautious with band placement and testing. He was demonstrating slowly and deliberately to a friend on how to use one. Then to all of our surprise it failed for unknown reasons after being very reliable on many flights.

    Maybe I’m very ignorant but because of seeing that failure I’m just not a personal fanboy of JLCR. I’ve read up on how if you ground test it wrongly it can not deploy at all in flight. Biggest complains I hear is unit isn’t beep or whatnot when reset and is prone to user inducing error after ground test if not aware of flaws. My only serious issue with single deploy apogee flight was when a launch rod angle was off in Kentucky and I had the rocket go off the range. It was stupidly windy like over 12mph, lost line of sight into neighborhood, and I was the first guy off the 1010 rail and we became aware the angle was borked after launch. I got my rocket back someone brought it back to range. Anyways I’m done here and I hope my advice helps you make your mind up.

    That same day in Kentucky a guy tried 7k ft apogee deploy it and needless to say we saw a L2 kit drift very very far off until it visually looked like a pixel then he told us no tracker. I don’t think they ever got that rocket back. It was some of the stupidest wind conditions I’ve flown rockets in.
     
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  14. Dec 13, 2019 #44

    John Taylor

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    Thank you Andrew!!! I needed every word you wrote.
     
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  15. Dec 13, 2019 #45

    rharshberger

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    You have practiced with the JLCR on the ground, now go fly it a few times, the experience you gain from that will increase your confidence in a device that works very well. I have flown my JLCR quite a bit and there are several things to watch out for one you know is keeping the bundle intact until the JLCR opens. Make sure and tether the JLCR in such a way as to put no stress on it during chute bundle deployment, I like to tether mine to the chutes swivel or quick link, I learned the hard way that tethering it to far from the chute can cause the bundle to be pulled out of the rubber band causing opening at higher than planned altitude.
    Make sure your practice flights are all easily visible from the ground, that way you can watch the recovery system deploy.
     
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  16. Dec 13, 2019 #46

    John Taylor

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    Thanks everyone for your help, I'll post the flight results for my certification attempt Sat pm
     
  17. Dec 17, 2019 #47

    John Taylor

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    Got my level2 cert Saturday! Rubber band broke at Apogee so long walk but worth it. IMG_9760.jpeg
     
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  18. Dec 17, 2019 #48

    timbucktoo

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    Congrats!
     
  19. Dec 17, 2019 #49

    g.pitts

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    Congratulations, John! I’m going for my L2 this spring - fingers crossed. [emoji51]
     
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  20. Dec 18, 2019 #50

    jpoehlman

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    Congratulations again John. Great to see you jumping back in!
     
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  21. Dec 18, 2019 #51

    John Taylor

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    Thanks Jack! Hope to see ya at a launch soon!
     
  22. Dec 19, 2019 #52

    John Taylor

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    Your already level one so a baby J is just a little more. Study the questions and the sources of the material and I would be shocked if you dont get 100.
    Keep it as simple as possible. Do what you know already how to do successfully. You'll do fine. After you get it then you can go crazy with complexity.
    Just my humble advice.
     
  23. Dec 19, 2019 #53

    g.pitts

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    Thank you, John! I’ve already taken and passed the test, so just waiting on our club’s next high power launch.

    I’m spending the down time improving my electronics bay. Hope to have a post on this effort sometime in January when I’m happy with my efforts.
     
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  24. Dec 20, 2019 #54

    Nytrunner

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    And for the other side of table, use your L2 as a learning opportunity and use a more powerful motor. Leave the baby J's for weekend fun later
     
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  25. Dec 20, 2019 #55

    g.pitts

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    Thanks @Nytrunner! I have a J180T for my L2 cert flight (no idea if that’s a “baby J”?). I flew the same rocket with an I599N-P for my L1 certification flight. That proved out the rocket’s ability to handle respectable G forces (15.9Gs for an L1 flight is pretty decent I guess, but far from 100Gs of some of my rocket club friends’ exploits with L3 flights!). It also proved out dual deployment, albeit with a single altimeter (had one fail the day before launch). The L2 flight will absolutely have redundancy!

    Projected altitude for the L2 very flight is just under 2600’, and given the terrain we launch in I’m including an Eggfinder in my electronics bay design.

    So learnings from L2 - assuming it is successful - include higher N-s motor of the J family, redundancy with my altimeters, and rocket tracking. And of course an unsuccessful attempt will provide any learnings from what went wrong since we learn more from failure than success!
     
    Last edited: Dec 20, 2019
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