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  1. #1
    Join Date
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    Lost a rocket with a working Eggfinder GPS on board - ideas?

    Folks,

    Yesterday I launched my Formula 38 on many motors, the last one being an H115-DM flight, with a working EggFinder MINI GPS tracker in the nose cone. EggFinder was correctly providing coordinates of the launch pad before each launch, so I got emboldened to fly out of sight. I should mention that this was my first day flying with the Eggfinder.
    Pics of the rocket can be found here:
    http://www.rocketryforum.com/showthr...18#post1732018

    The bright orange rocket took off in a hurry, leaving a beautiful trail of H115 dark-matter fire-sparks.
    It went quickly went out of sight (simmed to over 4K feet), never to be seen again.

    Eggfinder Mini was working throughout, LCD receiver beeping and updating the GPS coordinates transmissions. After ~2 minutes the coordinates finally settled down at a nearby soy-bean field.
    I walked to the indicated coordinates - nothing.

    Questions to anyone who has had some experience with Eggfinder or GPS trackers:
    1). Eggfinder LCD reciever was beeping throughout the flight, decreased in beeping frequency post landing, and increased in beeping frequency as I walked to the field indicated by last known coordinates transmitted. What does increased frequency of beeps mean, if anything? I believe beeping, in general, indicates data transmission. Does varying frequency of beeps mean anything?
    2). Transmitted Eggfinder GPS coordinates continued to be updated for ~1 hour I searched for the rocket, changing at the 2nd/3rd decimal digit continuously. For example, they went from (40.90005, -74.86992) to (40.90017, -74.87016) to (40.90033, -74.86997) to (40.90031, -74.86989). Is this expected? Indicative of something?
    3). We walked and combed the GPS coordinates area, all within a 50' foot radius on the edge of a soy bean field (dry plants about knee high) and a drainage ditches - nothing! I stood over multiple GPS coordinates spots looking for a hole in the ground, or a detached nose cone with tracker in it - nothing!

    My MadCow f38 has bright orange body that would have been hard to miss.
    It also carried Altimeter 3. I tried connecting to the Altimeter over BT (~30 foot radius), but it never connected near the search coordinates.

    Possibilities:
    (A). The GPS coordinates transmitted by Eggfinder Mini were total garbage, but even if so, why were they continuously changing?
    (B). The GPS coordinates corresponded to some event that happened during apogee, then the rocket landed elsewhere, but was transmitting stale coordinates?
    (C). Some event at apogee separated (black) nose cone from the bright orange body, and I just never found that black nose cone that contained the Eggfinder transmitter.

    I'm currently thinking #(C) is the most probable explanation, though detaching the 1/4" Kevlar shock cord would have taken something extraordinary.


    a

    P.S.: Needless to say this has shaken my faith in Eggfinder GPS, and put further plans to rely on it in the future on hold.

    Last edited by afadeev; 12th November 2017 at 05:31 PM.
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  2. #2
    Join Date
    23rd November 2013
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    2,217
    How are you translating coordinates to actual location?


    Sent from my iPhone using Rocketry Forum


  3. #3
    Join Date
    23rd November 2013
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    Did you look here?

    Click image for larger version. 

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    This is what I got using your last set of coordinates.


    Sent from my iPhone using Rocketry Forum

  4. #4
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    Quote Originally Posted by Lowpuller View Post
    Did you look here?
    This is what I got using your last set of coordinates.
    Indeed.
    For ~1 hour, with 4 people combing the area.
    That location, and everywhere around it.
    The irrigation ditches between the access road and the fields support tall reeds/weeds, so it's not the easiest place to search.

    The rocket is bright/fluorescent orange.
    It would have been hard to miss, even if the chute never deployed (for some reason).

    a
    Last edited by afadeev; 12th November 2017 at 06:06 PM.
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  5. #5
    Join Date
    9th May 2009
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    Quote Originally Posted by afadeev View Post
    2). Transmitted Eggfinder GPS coordinates continued to be updated for ~1 hour I searched for the rocket, changing at the 2nd/3rd decimal digit continuously. For example, they went from (40.90005, -74.86992) to (40.90017, -74.87016) to (40.90033, -74.86997) to (40.90031, -74.86989). Is this expected? Indicative of something?
    The distance between the first and last set of coordinates is about 100 feet, which is a little larger than one usually sees for a GPS with a good view of satellites, but not completely unexpected if the unit was upside down and/or had a poor view of the sky.

    I'd vote for your third explanation, that you had a separation and you just didn't visually find the piece with the Eggfinder in it.

  6. #6
    Join Date
    11th February 2017
    Location
    south Florida
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    I'm so sorry you lost such a beautiful rocket and the electronics, hope they turn up. Maybe the field will be mowed, does the rocket have a label with your name and number? I've started putting labels on each piece of my rockets, in case of an improper separation. How was it attached to the NC? The 1/4" kevlar would not break easily. I recently almost lost a tracker and NC when an elastic shock cord broke at ejection. The NC landed in a swampy area with high grass. The tracker led me to it but it was invisible from 8' away, I had to practically step on it to find it. Good luck!
    Last edited by billdz; 12th November 2017 at 06:42 PM.

    L1 3/25/17 H135
    L2 8/12/17 J180

  7. #7
    Join Date
    26th November 2009
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    4,912
    A nosecone falling ballistic most likely would have destroyed the tracker. Yes, even if you epoxied the antenna to the base, you would have had nothing to go on with a dead tracker except if you caught a few positions before it hit. That's how many folks recover ballistic flights myself included. You still had coordinates coming out after the presumed landing as screwy as that sounds. If the NC separated from the sustainer under the chute it should have drifted "really" far as opposed to with the
    sustainer and empty motor casing attached.

    What I think was happening since it sounds like you left with the tracker still beeping, is the position of the GPS receiver antenna was pointing towards the ground or towards the horizon and didn't have a good lock.

    I track and test on a live map and one can see the position jump all over the place on the ground which can be dependent on the receiving GPS antenna position and the nature of the GPS satellite constellation
    at the time of the flight. I've seen stuff 100 to 200 feet off with suboptimal reception of the GPS signals.

    If one lands out in the open, it's not so bad. A lot of times you see the rocket long before you get to the coordinates. Also if manual tracking, one needs to make sure they are inputting the data correctly into their handheld GPS or app as that could send them on a wild goose chase with the wrong units.

    Another thing, if your rocket was underwater I think the tracker would have died quickly unless the nosecone was watertight and floating. In that case, someone would probably have seen it in a shallow drainage ditch.

    Some advice:

    1. First time GPS fliers resist the urge to punch the rocket to outer Mongolia the first time. Get a few flights under your belt with motors that give you a good chance of recovering the rocket within sight. You can mess around with
    your procedures in a non-stressed manner to see how they work knowing you can still pickup your rocket and try again if there is a quirk or problem. Stupidhead here lucked out on a couple of early "outta sights" but I regressed and flew several NMEA trackers with lower powered motors so I could get more confidence after some difficult recoveries. I got lucky on some out of sight rockets with the NMEA trackers. (That is opposed to the Ham trackers on 400Mhz that use the APRS protocol which I also use.)

    2. Please take that tracker bay, go out into a field and do a range test before flight. If you don't, you could get the sickening no signal at altitude. I know that didn't happen in this scenario but be forwarned if one's
    installation has problems.

    3. If at all possible, fly with a beeper or screamer on the harness. ESPECIALLY if flying with tall grass or vegetation nearby. Yeah, I confess I've flown without a beeper due to room constraints and I
    darned near left a MCR/RW 38 Special beeping positions in a no-till cornfield. Stupidhead here was tracking on a live map and "thought" he was on top of the rocket. Stupidhead finally zoomed in on the map and I walked right
    up to the stupid rocket! (The JLCR worked but the chute couldn't get out of the nomex protector as it was curled and stiff.)

    Live map tracking with NMEA trackers and bread crumbing is not there yet for all users. Everything I use has been hacked to heck and has a high learning curve. If I had been able to track this flight and if it seemed your rocket location on the ground was jumping all over the place, I would have looked for the last breadcrumb position while the rocket was still up in the air but as low to the ground as possible. That might have provided a
    clue as to it's last, low "in-flight" position. (In fact that is the way to go after a ballistic flight. Since the rocket is coming in so fast, it's usually resting right "underneath" that last position from 50 to 100 feet in the air.)
    If we were able to receive valid positions while under the chute we could have developed a drift trend and had some further clues as to where it touched down. With the GPS antenna not in a favorable position
    at touchdown it could have sent you off all over the place except to there the rocket was lying. (Except if you were able to record the "wild" positions on a map that might have helped develop a trend like shown in the
    pictures below.)

    Better luck next time and really, do the range test and use some motors to keep you down low for awhile. Can also consider GPS Rocket Locator. If one can get that up, it can give you some idea of the proximity
    of where the rocket landed. Kurt
    Click image for larger version. 

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    This is an example of bread crumbing with an EggFinder. The altitudes for some reason are off in dynamic flight. Red line is the rocket, black line is the recovery path. You can see the "bread crumbs".
    Example of a stationary spread using the UBlox Ucenter program for a Ublox GPS chipset in the other picture. The GPS is on the ground, facing up and actually has a good lock. You can still see
    a variation there. Last night I did a test with a 3DR radio and cripes even with the GPS antenna pointing up the spread was terrible. (Didn't take a picture of that!)

    Click image for larger version. 

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    Last edited by ksaves2; 12th November 2017 at 07:05 PM. Reason: Add a line

  8. #8
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    Quote Originally Posted by billdz View Post
    I'm so sorry you lost such a beautiful rocket and the electronics, hope they turn up. Maybe the field will be mowed, does the rocket have a label with your name and number?
    I've started putting labels on each piece of my rockets, in case of an improper separation.
    No label, though it sounds like a great idea.
    Where do you attach yours?

    The farmer regularly collects and returns rockets to our club, and mine being a FG variety, is more likely to survive a few weeks out in the open. Unless it landed in the irrigation ditches, in which case ... I may just go back and look for it again tomorrow...

    Quote Originally Posted by billdz View Post
    How was it attached to the NC? The 1/4" kevlar would not break easily. I recently almost lost a tracker and NC when an elastic shock cord broke at ejection. The NC landed in a swampy area with high grass. The tracker led me to it but it was invisible from 8' away, I had to practically step on it to find it. Good luck!
    1/4" kevlar was epoxied to the motor mount, and tied + epoxied to a welded nose cone hook. Motor mount separation/disintegration would have required an epic CATO, which is more likely at launch, not at apogee.
    Nose cone hook was attached to an Eggfinder nose cone sled, similar to pics here:
    http://www.rocketryforum.com/showthread.php?142710-EggFinder-and-EggFinder-Mini-Sleds-and-All-Thread-Free-Mounts

    Long story short, I don't see the nose cone detaching short of a massive CATO at apogee, which is not likely, and even if it happened, I would have likely heard something.
    The H115-DM is a DMS motor, so I did not build it.
    It's not impossible that the ejection charge seal failed, or never fired at all, or something else weird happened.
    But I don't have any evidence of anything at this point.





    Quote Originally Posted by ksaves2 View Post
    A nosecone falling ballistic most likely would have destroyed the tracker. Yes, even if you epoxied the antenna to the base, you would have had nothing to go on with a dead tracker except if you caught a few positions before it hit. That's how many folks recover ballistic flights myself included. You still had coordinates coming out after the presumed landing as screwy as that sounds. If the NC separated from the sustainer under the chute it should have drifted "really" far as opposed to with the sustainer and empty motor casing attached.
    Agreed.
    Assuming coordinates were semi-good and coming from a live tracker post landing (I assume that's what ongoing beeps represent, waiting on confirmation from Chris), rocket is likely to have landed in one piece. The only question now is locating it.


    Quote Originally Posted by billdz View Post
    The ejection charge must have fired, otherwise it would have lawn darted and the tracker would have stopped sending telemetry.
    I looked at the map, what's that between the road and the cultivated area, just shrubs?
    That is an irrigation ditch, with about 3-foot wide stream at the center, and a buffer area of 5-10 feet of reeds and tall weeds on each side. There are smaller irrigation ditches on each side of the fields, feeding yet more reeds and weeds growth patches. Fun place to look for a rocket!

    I did randomly wade into the weeds (pun intended) looking for my rocket, but had no way to systematically inspect all of it.
    I am 100% sure it's not on the cultivated soy bean field. That one we had crisscrossed multiple times.

    At this point, I'm fixing my FPV drone (another long story why it needs fixing), and hoping it take it with me for another look tomorrow.


    Quote Originally Posted by ksaves2 View Post
    What I think was happening since it sounds like you left with the tracker still beeping, is the position of the GPS receiver antenna was pointing towards the ground or towards the horizon and didn't have a good lock.

    I track and test on a live map and one can see the position jump all over the place on the ground which can be dependent on the receiving GPS antenna position and the nature of the GPS satellite constellation at the time of the flight. I've seen stuff 100 to 200 feet off with suboptimal reception of the GPS signals.
    I signal locked the Eggfinder on the hood of the car, then inserted it into the nose cone once LCD was receiving good transmission. I did fly it once on an F-motor, and it was sending good signals from the launch pad, and the F-motor landing spot a hundred feet away.
    That much it worked.
    Technically, it looked like it also worked after H-flight landing, it's just that I could not see the bright orange rocket where the Eggfinder said it would be.
    That, plus the Eggfinder GPS coordinates were changing continuously. I still don't know what of make of that!


    Quote Originally Posted by ksaves2 View Post
    Some advice:

    1. First time GPS fliers resist the urge to punch the rocket to outer Mongolia the first time. Get a few flights under your belt with motors that give you a good chance of recovering the rocket within sight. You can mess around with your procedures in a non-stressed manner to see how they work knowing you can still pickup your rocket and try again if there is a quirk or problem. Stupidhead here lucked out on a couple of early "outta sights" but I regressed and flew several NMEA trackers with lower powered motors so I could get more confidence after some difficult recoveries. I got lucky on some out of sight rockets with the NMEA trackers. (That is opposed to the Ham trackers on 400Mhz that use the APRS protocol which I also use.)

    2. Please take that tracker bay, go out into a field and do a range test before flight. If you don't, you could get the sickening no signal at altitude. I know that didn't happen in this scenario but be forwarned if one's installation has problems.

    3. If at all possible, fly with a beeper or screamer on the harness. ESPECIALLY if flying with tall grass or vegetation nearby. Yeah, I confess I've flown without a beeper due to room constraints and I darned near left a MCR/RW 38 Special beeping positions in a no-till cornfield. Stupidhead here was tracking on a live map and "thought" he was on top of the rocket. Stupidhead finally zoomed in on the map and I walked right up to the stupid rocket! (The JLCR worked but the chute couldn't get out of the nomex protector as it was curled and stiff.)
    I sort of did #1 and #2.
    I considered, but skipped #3, mostly for space considerations. I lived to regret that dearly.

    The other thing I wished I did was to fire up my l laptop, and record the stream of GPS coordinates with the USB receiver. It was just a bit too cold, and I had kids and relatives to entertain during the launch, so I compromised on not bribing the laptop and the on-board video cameras, to have fewer things to juggle.
    That was not a good thing either, as this left me without the GPS bread crumbs trail that would have come in handy just about now.



    Quote Originally Posted by ksaves2 View Post
    With the GPS antenna not in a favorable position at touchdown it could have sent you off all over the place except to there the rocket was lying. (Except if you were able to record the "wild" positions on a map that might have helped develop a trend like shown in the pictures below.)
    That's my biggest fear right now - that I've been chasing useless GPS coordinates...

    I am certainly re-calibrating my expectations from flying with a GPS tracker.

    a
    Last edited by afadeev; 12th November 2017 at 09:19 PM.
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  9. #9
    Join Date
    11th February 2017
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    south Florida
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    I just stick labels with "REWARD" and my phone number on the outside of the lower and upper airframes, although some put the labels on the inside, which makes the rocket look nicer but may make the label hard to see.

    The ejection charge must have fired, otherwise it would have lawn darted and the tracker would have stopped sending telemetry.

    I looked at the map, what's that between the road and the cultivated area, just shrubs?

    L1 3/25/17 H135
    L2 8/12/17 J180

  10. #10
    Join Date
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    I looked over your posts. That's a very nice rocket, and it's a shame to give up when you know *approximately* where it is.
    If I understand correctly, you believe the rocket went about ~4000 ft high and landed about ~750 ft from the launch pad.
    You did not have a visual on the descending rocket, but you have Eggfinder coordinates.

    Eggfinder LCD beeps
    The LCD should beep when it receives a transmission from the TX in the rocket. The beeps are a very regular pattern (at least on my LCD). There is no variation in beeping frequency. Something like "beep, beep, beep, double beep, beep, beep, beep, double beep." (repeating) The only variation is when the LDC looses the TX signal, then there are no beeps. If you loose signal, the LCD display indicates how long it's been since the last signal.

    Accuracy of the coordinates
    Expect the accuracy of the coordinates to veri based on the number of GPS satellites the TX has locked-on. The LCD will display the number of satellites. Real-World accuracy with the maximum amount of satellites is a radius of 30-50 feet or so. This means the rocket might NOT be exactly pin-point where the coordinates say it is, but you are likely close if you are hearing the steady beep pattern of the LCD.

    You are looking for the TX
    If you did not have any visual on the descending rocket, then you have no way of knowing if the rocket is located in the same place as the TX. Remember you are getting signals from the TX, not the rocket. They may have become separated.

    IF it were me - I would not give up the search
    The TX, and probably the rocket too, is located somewhere near the coordinates you had. I would search a 250' radius, knowing the rocket (or at least the TX) is most likely to be closer to the center of the circle.

    Good Luck.

    Picture of 250' radius around coordinates. Is that the launch area on the right?
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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    -Scott Sager
    NAR 91621 L2
    TRA 15982 L2
    Woosh #558
    KC9WQK

  11. #11
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    Quote Originally Posted by scsager View Post
    I looked over your posts. That's a very nice rocket, and it's a shame to give up when you know *approximately* where it is.
    If I understand correctly, you believe the rocket went about ~4000 ft high and landed about ~750 ft from the launch pad.
    You did not have a visual on the descending rocket, but you have Eggfinder coordinates.
    Exactly right.

    Quote Originally Posted by scsager View Post
    Eggfinder LCD beeps
    The LCD should beep when it receives a transmission from the TX in the rocket. The beeps are a very regular pattern (at least on my LCD). There is no variation in beeping frequency. Something like "beep, beep, beep, double beep, beep, beep, beep, double beep." (repeating) The only variation is when the LDC looses the TX signal, then there are no beeps. If you loose signal, the LCD display indicates how long it's been since the last signal.
    I attribute my beeping frequency variation on the fact that it was not getting a good signal from the launch pad spot, but once I walked to the designated GPS landing coordinates, started getting regularly location updates every second.
    The steady beeps were encouraging, but the fact that they were accompanied by a slight variation to the GPS coordinates only served to confuse the situation.

    Here are the LCD receiver screen pictures.
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    Quote Originally Posted by scsager View Post
    Accuracy of the coordinates
    Expect the accuracy of the coordinates to veri based on the number of GPS satellites the TX has locked-on. The LCD will display the number of satellites. Real-World accuracy with the maximum amount of satellites is a radius of 30-50 feet or so. This means the rocket might NOT be exactly pin-point where the coordinates say it is, but you are likely close if you are hearing the steady beep pattern of the LCD.

    You are looking for the TX
    If you did not have any visual on the descending rocket, then you have no way of knowing if the rocket is located in the same place as the TX. Remember you are getting signals from the TX, not the rocket. They may have become separated.

    IF it were me - I would not give up the search
    The TX, and probably the rocket too, is located somewhere near the coordinates you had. I would search a 250' radius, knowing the rocket (or at least the TX) is most likely to be closer to the center of the circle.

    Good Luck.

    Picture of 250' radius around coordinates. Is that the launch area on the right?
    Thanks for the encouragement and feedback.
    I'm fixing my drone (Hubsan X4 501s), charging spare batteries, and planning to go back out to take another look tomorrow.

    a
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  12. #12
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    Ok, Saw your screen shots. You had a lousy lock with only a 3 satellite lock. The GPS antenna might have been in a bad position. You should have come back every hour and seen if the satellite constellation had changed enough to get a better lock.
    That said, your search area is going to be large, perhaps more than what Scott shows. Try this for a bit of info: http://wiki.openstreetmap.org/wiki/Accuracy_of_GPS_data

    If you have an Android phone or tablet, even if it doesn't have service you can download "GPS Rocket Locator" and you get an HC-06 or HC-05 B/T module wired into your LCD you can monitor your data stream: https://play.google.com/store/apps/d...tlocator&hl=en

    If your phone doesn't have data service, you can still download maps for off line use in the area you are flying in by using WiFi. If the rocket ends up in an area your device doesn't have a map for you can still use it to track.

    If your phone does have data service you can download the needed map on the fly.

    Enter and setup your device for "developer mode" and you can select allow "mock locations". With this you can download Bluetooth GPS: https://play.google.com/store/apps/d...id.btgps&hl=en
    Open it and select the HC-06 or 05 device that's feeding you your rocket position and see what GPS satellites your tracker is using and the state of the GPS constellation. Scroll to the end and you can see a map if you have a live data connection
    but you can't use this program to directly navigate keeping track on the rocket and your local location.

    Now if you have a device that has a back camera you might want to try this program: https://play.google.com/store/apps/d...gnssview&hl=en

    Put in your position and this program will give you an idea of the condition and position of all the GPS satellites that are flying from all nations relative to your location. You can hold up your device to the sky and it will show the relative position of
    the satellites overlayed on the sky picture your camera is showing you! Works on my Nexus 7 2013 but not my Blu phone. Even if the camera thing doesn't work it can show you the condition of the constellation and predict what it's going to look like in
    the future. Good luck next time. Kurt
    Last edited by ksaves2; 12th November 2017 at 09:48 PM. Reason: saw the screen saves.

  13. #13
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    Quote Originally Posted by afadeev View Post
    Here are the LCD receiver screen pictures.
    Doesn't that "3" mean there are only 3 satellites in lock? You can't get a full 3D GPS fix with less than 4 sats, so I'd be suspicious of these coordinates. At a minimum it means that the GPS had a very bad view of the sky.

  14. #14
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    Quote Originally Posted by mikec View Post
    Doesn't that "3" mean there are only 3 satellites in lock? You can't get a full 3D GPS fix with less than 4 sats, so I'd be suspicious of these coordinates. At a minimum it means that the GPS had a very bad view of the sky.
    Yup, Can't get elevation that's why the "110". I'm afraid that horizontal precision was likely very poor. I've seen this situation when I was trying to test a setup indoors. Just wouldn't lock well until I took the tracker outside. Kinda handicapped with
    lousy cold weather. Kurt

  15. #15
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    Don't give up. I spent 2 hours in a bean field walking around my rocket. The GPS was within 6 feet of it but, I still could not find it. When I finally found it you could see my tracks all around it!

  16. #16
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    If it landed in the stream, it could travel pretty far down stream. Seen it happen at MDRA's Red Glare launches with the irrigation ditches.
    Kevin Wuchevich
    Tripoli Pittsburgh
    TRA 12238

  17. #17
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    I haven't used the EggFinder GPS and only have 4 flights with the MissileWorks T3 with the GPS Rocket Locator app, but I've been doing Geocaching for years now and one thing I know from caching, when you get poor lock, your accuracy can get to be +- 150 ft. or worse. When you have a good lock and stand still for a length of time, it will get down to +- 15 ft. or less. From what others have said about only having a 3 satellite lock, I would find the center of those locations and then search out in a radius to about 200 ft. to 300 ft. That's a lot of ground, but that is probably as accurate as your signal is.
    Handeman

    TRA #09903 L3 3/29/2015

    "If you don't use your head, you have to use your feet!" my Dad

    Tripoli Central Virginia #25 - BattlePark.org

  18. #18
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    Quote Originally Posted by cavecentral View Post
    If it landed in the stream, it could travel pretty far down stream. Seen it happen at MDRA's Red Glare launches with the irrigation ditches.
    It's possible but I don't think it's in the drainage ditch. If it was in the water I think the tracker would have stopped transmitting quicker. It could be real close to the drainage ditch but I don't think the tracker is underwater. Kurt

  19. #19
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    1,267
    Three satellites can only give you a 2D fix. You need minimum of four for the 3D fix. The more satellites locked over wide expanses of sky the better the fix.

    Try cat circles to find your rocket. When cats get lost they start walking in small circles from where they are, and gradually make the circle bigger as they spiral outwards. Eventually they find somewhere they know and can get back home from there. That's the plan anyway
    TRA 13430, Level 3

    "Everybody's simulation model is guilty until proven innocent" (Thomas H. Lawrence 1994)

  20. #20
    Join Date
    11th April 2017
    Location
    Brisbane Australia
    Posts
    617
    Quote Originally Posted by OverTheTop View Post
    Try cat circles to find your rocket.
    LOL.. walking in a sod field yesterday, the initial fix I got (forgot to check the # of satellites before I jumped in the car) was in the middle of the SOD field.. (it ended up being at the fringe of the road about 20m before I pulled over.. I literally drove past it...)

    Those sod fields are unexpectedly hard to walk in - even with sturdy boots, I almost rolled my ankle 3-4 times trying to walk a cat circle, just as you described it (except until now, I didn't know what they were called)..

    The solution to prevent ankle rolling on the deceptively uneven terrain was to actually RUN - the greater impact from my feet would flatten the sods rather than tripping on them, so my only modification to your suggestion would be, if in a SOD FIELD: RUN CAT CIRCLES TO FIND YOUR ROCKET...
    Reasonably new to rocketry and hailing from the land down under.. I speak metric... I know not of these feet and inches you speak of...

    QRS: #193
    AMRS: #148

  21. #21
    Join Date
    9th October 2013
    Location
    San Jose, CA
    Posts
    659
    I think everybody else has covered the common things, but I'll throw one more possible wrench in the works. I don't know if they're only doing it out here (well, southern CA), but there have been lots of warnings at launches I've gone to this year about the military messing around with GPS interference, where we've been warned that GPS locations could be distorted by quite a bit (and the radius of the interference area has been hundreds of miles at times). I never saw it hit any of my flights, but I heard other flyers complaining that it led to serious jumps in the reported positions (or messing with their nav system, etc). But only having 3 satellites locked certainly doesn't help, probably landed with the GPS antenna facing down or something like that, unless the number wasn't any better on the pad where maybe you have metal obstructing it, or the GPS antenna was somehow damaged, etc.

    Actually I looked back at one of the club's discussions around GPS testing back in April, and the current document definitely shows testing in other parts of the country as well: https://www.navcen.uscg.gov/pdf/gps/...terference.pdf
    Will Ferry (Launches & Videos) NAR #96512 (L2) / TRA #15328 (L2) / LUNAR #2759
    L1: 9/2013 @ XPRS, GLR T-Bolt "Thunderbolt" (R.I.P.), H148R
    L2: 4/2016 @ TCC Helm, Binder Design Excel w/DD "dd2.xls", J315R
    Impulse flown (flights): 2013: 767Ns (2), 2014: 4298Ns (8), 2015: 7486Ns (16), 2016: 11693Ns (18), 2017: 11138Ns (16)

  22. #22
    Join Date
    12th September 2013
    Location
    SE Wisconsin
    Posts
    1,031
    Quote Originally Posted by Maxter View Post
    Don't give up. I spent 2 hours in a bean field walking around my rocket. The GPS was within 6 feet of it but, I still could not find it. When I finally found it you could see my tracks all around it!
    I have been surprised by how big a rocket can hide in the furrows of a freshly ploughed corn field.

    I second the suggestion to have some kind of beeper on board. My elder boy flew his scratch built 29mm F-F two stage with eggfinder and Quark on board. He came back with the nose cone and eggfinder. The whole family went out again and searched downwind of that point. Eventually one of us heard the beeping from the Quark. That person froze where he could hear it (so we didn't loose that hint), and the rest searched around him - and found the rest of the rocket.

    I have a cheapy parabolic mic from Amazon that's part of my launch kit for just this purpose - but bare ears seem to work well enough.
    Charles McGonegal
    Ciderwright at AeppelTreow Winery & Distillery
    www.appletrue.com
    NAR #103560 L1 6/25/17 Estes Leviathan CTI H175-SS
    Ad Astra Tabernamque!

  23. #23
    Join Date
    21st September 2017
    Location
    NY/NJ
    Posts
    218
    Quote Originally Posted by Maxter View Post
    Don't give up. I spent 2 hours in a bean field walking around my rocket. The GPS was within 6 feet of it but, I still could not find it. When I finally found it you could see my tracks all around it!
    Thanks, guys, I wont.
    I was going to go out with a drone today, but it's 39F and raining outside right now.
    The rocket is all fiberglass, so rain should not damage it. But the last time I stepped onto those farm fields after an overnight rain, my boots turned into dirt/clay anchor weights. Incredibly clingy dirt that actually stained my hiking boots black. The fields are just impassible today.
    I'm traveling later this week, so further search will have to wait until the coming weekend.


    Quote Originally Posted by Charles_McG View Post
    I second the suggestion to have some kind of beeper on board.
    Funny thing is that I ALWAYS flew my high altitude rockets with a beeper, which saved the day countless times ... until I got the Eggfinder.

    Well, the primary reason was that the long H-motor was taking up too much space, and I would have had to really cram the chute, the altimeter, and the beeper into what little space remained on top of the 38mm airframe. And the altimeter and beeper did not fit side-by side, so going inline made for an interesting packaging challenge. I was worried all the extra gear would get in the way of chute deployment.

    That, plus I had too much faith in the Eggfinder GPS.

    I clearly have a LOT to learn about GPS, satellite counting and tracking, and why it's not as consistent as what we have in our phones.
    And I am back to flying with the beeper.
    All the time.

    a
    __
    Radrocketeers.org NAR L2

  24. #24
    Join Date
    11th February 2017
    Location
    south Florida
    Posts
    571
    Is it normal for a GPS tracker in an open area to see only 3 satellites? My tracker saw 9 at the last launch.

    A beeper/screamer does work. Someone in another thread recommended this one, very loud (140db) and just $7 shipped:
    https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
    I've bought two and am well satisfied. In an HPR launch, you can't hear the beeper at apogee, and it is cool how the sound first softly appears from the sky and gets louder as the rocket descends. Unless you are within 50 yards or so, you won't hear the sound once the rocket lands, although before impact the sound will give you a fix on the direction the rocket is heading.

    L1 3/25/17 H135
    L2 8/12/17 J180

  25. #25
    Join Date
    5th December 2013
    Location
    MD
    Posts
    6,973
    Nothing to add. Sorry for your loss. Hope you find it.

    John S. ---- NAR #96911 ---- TRA #15253 ---- MDRA #067 ---- BARC #028
    L1, 3/15/14: Aerotech Sumo, CTI H133BS
    L2, 6/21/14: Giant Leap Vertical Assault, CTI J240RL
    L3, 3/12/16: MAC Performance Radial Flyer, CTI M1101WH
    Altitude: 13,028', L3 flight; Speed: Mach ???, L3 flight

  26. #26
    Join Date
    26th November 2009
    Posts
    4,912
    Quote Originally Posted by billdz View Post
    Is it normal for a GPS tracker in an open area to see only 3 satellites? My tracker saw 9 at the last launch.

    A beeper/screamer does work. Someone in another thread recommended this one, very loud (140db) and just $7 shipped:
    https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
    I've bought two and am well satisfied. In an HPR launch, you can't hear the beeper at apogee, and it is cool how the sound first softly appears from the sky and gets louder as the rocket descends. Unless you are within 50 yards or so, you won't hear the sound once the rocket lands, although before impact the sound will give you a fix on the direction the rocket is heading.
    If there is anything to interfere with the satellite reception like the GPS receiver antenna pointing to the ground or the horizon then yes, position accuracy will stink. An amplified geo-helix Sarantel antenna/GPS chipset can improve on that but they are no
    longer available: http://www.csgshop.com/product.php?id_product=106 I had one of these but dropped it! Dang, I wished I ordered 4 of them. Lying on the ground they do pretty well.

    Again, this is where live mapping with bread crumbing might help a person because if you get that last known position 50 to 100 feet (or lower) in the air, that is the position to start a search from if you start getting screwy positions after landing.
    Keep in mind, this is not the Eggfinders fault. This condition could occur with any GPS tracker out there now if the GPS receiver antenna is in a lousy position after landing. Unless of course one can get a chipset with an amplified geohelix antenna
    like stated above. That would minimize the effects from this negative scenario.

    Also, when flying in an area with tall vegetation, it behooves one to stick a screamer on the harness. It's hard to beat the ears on the last 20 to 50 feet depending on the dB output of the screamer. I haven't had a recovery with the
    GPS antenna facing down or in a suboptimal position yet or if I did, the rocket was out in the open and a espied it from a distance. Kurt
    Last edited by ksaves2; 13th November 2017 at 08:02 PM.

  27. #27
    Join Date
    27th December 2014
    Location
    Seattle, WA
    Posts
    809
    The only downside of screamers is that power wires attract them, especially if they're close enough to camp to be really annoying until the linemen can come out to take the rocket down.
    NAR L1 "Cheeto Dust", scratch 54mm, H54R (before it became a G54), Mansfield, WA
    L2 "Arc Light", Madcow 2.6" Arcas, J285CL, Mansfield, WA, recovery by snowshoe

  28. #28
    Join Date
    12th August 2017
    Location
    Southeastern PA
    Posts
    2
    Quote Originally Posted by boatgeek View Post
    The only downside of screamers is that power wires attract them, especially if they're close enough to camp to be really annoying until the linemen can come out to take the rocket down.
    Or if they get caught in a farmer's 70 foot oak tree in his back yard...

    ...don't ask me how I know.

  29. #29
    Join Date
    21st December 2013
    Location
    Australia
    Posts
    463
    You don’t have logs from the entire flight? Full NMEA logs should indicate the quality of the lock, you should be able to see where it went bad after landing and go back to the previous coordinate.
    QRS: 124
    AMRS: 32 L2
    Highest Altitude: 10,849 feet
    Largest Motor: CTI 1115J530 IM
    Current Projects:
    Purple Parrot, X Wing


  30. #30
    Join Date
    26th November 2009
    Posts
    4,912
    Quote Originally Posted by SpaceManMat View Post
    You don’t have logs from the entire flight? Full NMEA logs should indicate the quality of the lock, you should be able to see where it went bad after landing and go back to the previous coordinate.
    One would have to be using a live tracking application in order to be able to save a log. I think the OP was using the method of manually lifting the final position off the LCD and in putting it into another application to find the position.
    Works most of the time but not in this case. The number of individuals flying GPS trackers has increased exponentially over the last couple of years. By mere chance some are going to have suboptimal experiences especially if they are new to GPS tracking. Kurt


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