sylvie369
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- Jan 20, 2009
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Despite some setbacks, I had a great day out at Bong yesterday. Two flights. The first was the first flight test of my GPS device, in a 4" rocket on a Pro38 4G red. Tim (Wildman) gave me a hand setting the delay on the motor, as I have never flown a Pro38 with motor deployment. That worked fine.
Here's the GPS device I designed and built:
https://i282.photobucket.com/albums/kk265/psmithalverno/XBee-GPS.jpg
It's a Byonics GPS "hockey puck" GPS connected to a board I designed and had BatchPCB fabricate. The board is connectors for the GPS and for the XBee radio, 3.3V and 5V power supplies, and a little circuit for inverting the data from the GPS.
There was a series of snafus. First of all, I powered it up and checked to make sure I was receiving data. Yup, no problem. So I set the rocket out on the pad, and put in an igniter. Then came back - and I wasn't getting data. As it turned out, the battery had died during that 10 minutes. Dave Finch gave me a new battery (thanks!), and I checked to make sure it was working. No problem. Set the rocket up again, and prepared the receiver. I'm sending by XBee to a netbook which sits at the rangehead, with the XBee sending all of the received NMEA data into a terminal program. I run "capture to file" to collect the data. Unfortunately, my terminal program is weird about where it puts files, and between that and the glare on the screen, I wasn't able to find my data while I was out at Bong (which, of course, defeats the purpose of onboard GPS). In fact all I could find was an empty file of the same name. But when I got home, I found the data file (only by searching the entire hard disk...sigh), and it was perfect. Here are the results
https://i282.photobucket.com/albums/kk265/psmithalverno/GPSFlightTest522010.jpg
(the red line is the GPS data transmitted from the rocket: blue is the track of a handheld GPS I carried while picking up the rocket. I set waypoints at the launch pad, receiver station, and landing point. The two straight lines on the trail are where GPS lock was lost during boost, as confirmed by a look at the altitude profile plot. It picked up again just fine under chute, though. I suspect that the little loop is an artifact of GPS re-acquiring satelites, not a real loop in the flight path, though I suppose it could be parachute deployment).
https://i282.photobucket.com/albums/kk265/psmithalverno/GPSFlightTestLandingSpot522010.jpg
https://i282.photobucket.com/albums/kk265/psmithalverno/GPSFlightTestLandingmeasure522010.jpg
(these are made by uploading the raw data file to GPSVisualizer.com, and outputting results into Google Earth, then saving the Google Earth images)
When I was out recovering the rocket, I set waypoints corresponding to the launch pad, the position of my receiver, and the place where the rocket landed, using a handheld Garmin, which would be what I would use to guide me to the rocket in a real recovery. The last line of data received from the rocket had the same coordinates as the Garmin waypoint for landing to the third place after the decimal, which apparently (per Google Earth) corresponds to 13 feet on the ground. I wasn't careful to set the landing waypoint while standing by the electronics bay - I was back by the fin section at the time, so the true error was considerably less than that.
Of course I landed very near to the pad, and so this wasn't really a good test of the radio range, but it looks like if I do get the radio signal, the GPS data will be very usable.
=====================
For the second flight I put the same rocket up, with an I211, with a Boostervision Gearcam taped to the side. It flew to 1437 feet and got nice video:
https://s282.photobucket.com/albums... Videos/?action=view¤t=i211may22010.flv
For the impatient, launch is a little after the 2:45 mark, landing is 1 minute later, and I arrive to pick it up just after the 5:15 mark.
This is easily the best onboard video I've made. I'm very pleased with the Gearcam.
Here's the GPS device I designed and built:
https://i282.photobucket.com/albums/kk265/psmithalverno/XBee-GPS.jpg
It's a Byonics GPS "hockey puck" GPS connected to a board I designed and had BatchPCB fabricate. The board is connectors for the GPS and for the XBee radio, 3.3V and 5V power supplies, and a little circuit for inverting the data from the GPS.
There was a series of snafus. First of all, I powered it up and checked to make sure I was receiving data. Yup, no problem. So I set the rocket out on the pad, and put in an igniter. Then came back - and I wasn't getting data. As it turned out, the battery had died during that 10 minutes. Dave Finch gave me a new battery (thanks!), and I checked to make sure it was working. No problem. Set the rocket up again, and prepared the receiver. I'm sending by XBee to a netbook which sits at the rangehead, with the XBee sending all of the received NMEA data into a terminal program. I run "capture to file" to collect the data. Unfortunately, my terminal program is weird about where it puts files, and between that and the glare on the screen, I wasn't able to find my data while I was out at Bong (which, of course, defeats the purpose of onboard GPS). In fact all I could find was an empty file of the same name. But when I got home, I found the data file (only by searching the entire hard disk...sigh), and it was perfect. Here are the results
https://i282.photobucket.com/albums/kk265/psmithalverno/GPSFlightTest522010.jpg
(the red line is the GPS data transmitted from the rocket: blue is the track of a handheld GPS I carried while picking up the rocket. I set waypoints at the launch pad, receiver station, and landing point. The two straight lines on the trail are where GPS lock was lost during boost, as confirmed by a look at the altitude profile plot. It picked up again just fine under chute, though. I suspect that the little loop is an artifact of GPS re-acquiring satelites, not a real loop in the flight path, though I suppose it could be parachute deployment).
https://i282.photobucket.com/albums/kk265/psmithalverno/GPSFlightTestLandingSpot522010.jpg
https://i282.photobucket.com/albums/kk265/psmithalverno/GPSFlightTestLandingmeasure522010.jpg
(these are made by uploading the raw data file to GPSVisualizer.com, and outputting results into Google Earth, then saving the Google Earth images)
When I was out recovering the rocket, I set waypoints corresponding to the launch pad, the position of my receiver, and the place where the rocket landed, using a handheld Garmin, which would be what I would use to guide me to the rocket in a real recovery. The last line of data received from the rocket had the same coordinates as the Garmin waypoint for landing to the third place after the decimal, which apparently (per Google Earth) corresponds to 13 feet on the ground. I wasn't careful to set the landing waypoint while standing by the electronics bay - I was back by the fin section at the time, so the true error was considerably less than that.
Of course I landed very near to the pad, and so this wasn't really a good test of the radio range, but it looks like if I do get the radio signal, the GPS data will be very usable.
=====================
For the second flight I put the same rocket up, with an I211, with a Boostervision Gearcam taped to the side. It flew to 1437 feet and got nice video:
https://s282.photobucket.com/albums... Videos/?action=view¤t=i211may22010.flv
For the impatient, launch is a little after the 2:45 mark, landing is 1 minute later, and I arrive to pick it up just after the 5:15 mark.
This is easily the best onboard video I've made. I'm very pleased with the Gearcam.
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