Lost me a rocket

Discussion in 'Rocketry Electronics and Software' started by David Schwantz, Aug 12, 2019.

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  1. Aug 12, 2019 #1

    David Schwantz

    David Schwantz

    David Schwantz

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    LOC V-2, no chute went in going 500 mph?? No signal from Rocket Hunter. Had it taped with silicon tape to shock cord and antenna also taped to cord. I am guessing that it was destroyed, at the very least antenna ripped off. Painted the thing lederhosen green camo and it went into the corn. Yup, try to find that one:(
    Anyway, how are some of you protecting your GPS or RDF units?
     
  2. Aug 12, 2019 #2

    Buckeye

    Buckeye

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    Went in the corn ballistic? I like my GPS secured in an ebay. However, the RDF or GPS won't do you much good if it is buried in the ground. Fix the parachute deployment problem, first.
     
  3. Aug 12, 2019 #3

    timbucktoo

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    I tape my RF to cord with electrical tape but if it came in ballistic, doubtful tracker survived. Most electronics won’t survive that kind of impact unless housed in some foam protection. Most of my GPS trackers are nose cone mounted but like buckeye said, fix deployment issue first.
     
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  4. Aug 13, 2019 #4

    David Schwantz

    David Schwantz

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    Ya, don't know what happened, have had several flights on her, perfect. Motor was J520 DMS, saw no event, several people saw the same thing. And went into corn just like a V 2 should.
     
  5. Aug 13, 2019 #5

    K'Tesh

    K'Tesh

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    Sorry to hear that. It's never fun to see your work disappear.
     
  6. Aug 17, 2019 #6

    ksaves2

    ksaves2

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    You come in ballistic and it’s highly doubtful a tracker will survive. I did hear of a guy who had an RDF and ran around a spot with the Yagi antenna pointed to the ground and got a weak signal. Assumed the rocket was swallowed up and the tracker survived. Never did find the hole in the loose dirt of a newly plowed cornfield.
    It’s rare a tracker survives a truly ballistic impact where the nosecone or apogee charge fails. It the NC comes off and the drogue or main fails, the thing might pseudo tumble recover and a well packed tracker might survive a “flat” hit on the ground.

    That said, a GPS tracker might give one a little bit of an edge for the ballistic recovery as I and others have experienced receiving one or two positions just before impact and the tracker ultimately gives its life up. Since the rocket is coming in at high velocity, get a position when it’s 50 to 200 feet up in the air and it will narrow your search and you stand a better chance of finding the pieces or the fin can sticking out of the ground in the case of a fiberglass or carbon rocket. Just walk to the last position fix and you’ll likely find the rocket. High velocity descent doesn’t give much time for wind to change the trajectory.

    Had a ballistic “occurrence” with a Formula 54 I had shearpins on the NC and an NC mounted EggFinder. I under charged the ejection charge.
    The EF gave me a couple of positions before impact. I have hacked Ham radio software that allows me to track in real time on a photo map so it was just a matter of making the position dots connect and I found the fin can sticking out of the ground. The EF was toast and I broke the NC getting it out of the farm field, but the rocket body was/is in good shape and still flies with a new nosecone with a new EggFinder residing in it. Kurt
     
  7. Aug 17, 2019 #7

    Dipstick

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    My BRB gps rode at the front of a rocket that came in ballistic. My last known position brought me right to the impact zone...helpful but sad. :)
     
  8. Aug 17, 2019 #8

    Handeman

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    I had one rocket come in ballistic and the HiAlt45 in the av-bay survived and is still in use today. It only survived because the battery was on the other side of the sled and the sled broke just ahead of the altimeter. Fluke!

    BTW At that time I used the NASA terminal velocity tool to determine that a rocket with a Cd of 0.6 has a terminal velocity on earth at 600 ft above sea level of 294 mph. I now use 300 mph as the "close enough" value for terminal velocity or ballistic recovery/impact speed.
     
  9. Aug 17, 2019 #9

    billdz

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    Agreed, this is perhaps the main advantage of GPS over RDF. Just make sure the GPS tracker is set to report every few seconds. Some have a default setting which only sends a report once every 5 or 10 minutes, that's too slow for rocketry.
     
  10. Aug 17, 2019 #10

    Anthony Claiborne

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    I program my GPS to report every 2 seconds right after apogee. So, if the rocket descends on the other side of hills, I have the last GPS coordinates before losing LOS signal.
     
  11. Aug 17, 2019 #11

    ksaves2

    ksaves2

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    I had one of those too. At the time, BRB APRS on the 400mhz Ham band was the only game in town.
    I unfortunately used metallic paint that blocked Rf getting out of the rocket and I did an inadequate range test. Landowner returned the remains and told me the BRB GPS was smashed beyond repair. He’s a rocket guy so I trust him there. Put a new battery in the parrot altimeter and I got a nice parabolic ballistic curve pattern. Rocket only sat in the field for 3 days so didn’t get rained on.

    That was a bitter financial pill to swallow and a lesson learned to do an adequate range test with a new installation. Sure is a lot easier to trash a $50.00 Eggfinder bought on special than lose a $200.00+ tracker. Kurt
     
  12. Aug 17, 2019 #12

    Anthony Claiborne

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    I know what you mean. parabola.jpg
     
  13. Aug 17, 2019 #13

    Anthony Claiborne

    Anthony Claiborne

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    Here's what happened to the payload section. The altimeter ended up on the nose cone.
    9-27-17 Dyna Star.jpg
     
  14. Aug 18, 2019 #14

    David Schwantz

    David Schwantz

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    I am still hoping to find it before it goes through the farmers combine. But I have 3 big corn fields, one a 1000 yds long, and a bean field to search.
     

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