kevinkal
Insatiable Hobbyist
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- Feb 12, 2016
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Just this weekend I was able to try out my first ever tracker, an Eggfinder Tx. I use the Eggfinder LCD with a HC-06 Bluetooth Module to receive and transfer data to either my android tablet or my Windows 10 laptop. After a nice flight to 4600', I saw that the landing position shown on Mapshere running on my Laptop looked correct. I then closed Mapsphere and saved the track file upon exiting.
Now that I've been able to open the track file, I see that the GPS position and Altitude appear to be significantly in error, except for where the rocket sat on the pad before launch, and the portion of the flight where the main chute had opened. The ascent straight up was not represented correctly by the track data. Rather that a straight up flight, the track data shows a horizontal shift about 1000', then another shift back 1000' with an increase in altitude of 250 units.. which I assume are meters. The track should have shown a straight up shot to 4600 ft (roughly 1500 meters), and a slight northerly drift under the drogue. The data then appears to be correct where the main chute opened and the rocket slowed down from 60 fps to 15 fps and began to drift south until it landed. The GPS shown landing position was also correct.
So, is this normal performance? (My EggfinderTx uses the stock wire antenna, but I have the Upgraded SMA antenna sold by EggtimerRocketry. on the Eggfinder LCD). Supposedly, it should work well beyond 10,000 ft)
I was hoping to see useful altitude profiles.
Below I've attached a few descriptive pictures of my Tx install, track file, Mapsphere plots and corresponding in-flight video to show how straight up the flight was vs. what the Eggfinder/Mapsphere track looks like.
Here's the saved Mapsphere track, where I had to change the file extension from .gpx to .txt in order to upload here.
View attachment gpslog_16072016_151524 GPX.txt
Top Down Position. Starting point looks right, then only the last downward line to the ending point looks correct.
3D side view looking to north. Starting and Ending points look correct, but both position and altitude between launch and the main chute opening do not look correct. The line should basically go straight up, then come down slightly north, then just as shown in the last line segment before landing it should drift down from 700 ft agl and land.
Video of flight in which track data was recorded. Note how straight up and down the flight was until the southernly drift at the end under the main chute.
[video=youtube;zJxMuFOmZ1s]https://www.youtube.com/watch?v=zJxMuFOmZ1s[/video]
Now that I've been able to open the track file, I see that the GPS position and Altitude appear to be significantly in error, except for where the rocket sat on the pad before launch, and the portion of the flight where the main chute had opened. The ascent straight up was not represented correctly by the track data. Rather that a straight up flight, the track data shows a horizontal shift about 1000', then another shift back 1000' with an increase in altitude of 250 units.. which I assume are meters. The track should have shown a straight up shot to 4600 ft (roughly 1500 meters), and a slight northerly drift under the drogue. The data then appears to be correct where the main chute opened and the rocket slowed down from 60 fps to 15 fps and began to drift south until it landed. The GPS shown landing position was also correct.
So, is this normal performance? (My EggfinderTx uses the stock wire antenna, but I have the Upgraded SMA antenna sold by EggtimerRocketry. on the Eggfinder LCD). Supposedly, it should work well beyond 10,000 ft)
I was hoping to see useful altitude profiles.
Below I've attached a few descriptive pictures of my Tx install, track file, Mapsphere plots and corresponding in-flight video to show how straight up the flight was vs. what the Eggfinder/Mapsphere track looks like.
Here's the saved Mapsphere track, where I had to change the file extension from .gpx to .txt in order to upload here.
View attachment gpslog_16072016_151524 GPX.txt
Top Down Position. Starting point looks right, then only the last downward line to the ending point looks correct.
3D side view looking to north. Starting and Ending points look correct, but both position and altitude between launch and the main chute opening do not look correct. The line should basically go straight up, then come down slightly north, then just as shown in the last line segment before landing it should drift down from 700 ft agl and land.
Video of flight in which track data was recorded. Note how straight up and down the flight was until the southernly drift at the end under the main chute.
[video=youtube;zJxMuFOmZ1s]https://www.youtube.com/watch?v=zJxMuFOmZ1s[/video]
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