24 Sept 2009
- Full range test for all Piccolo links, Freewave links, and Ad-Hoc networking links with new antennas and cabling.
- Correlate PTH and wind data with doppler radar sampling.
Four successful flights of NexSTAR-2 were conducted, three of which were used to test various aspects of the VORTEX-2 deployment strategy and equipment, and the final test was used to gather RSSI data from the 802.11b link.
NexSTAR-2 Flight 1
Flight Time: 21.04 mins
Autonomous Flight Time: 18.76 mins
Shortly after getting the vehicle in the air it was noticed that the tracking vehicle was unable to command the UA to offset its tracking orbit. Unfortunately this was not easily fixed from the ground, and the flight was terminated.
The vehicle parameters used for the vrate loop had been modified and provided a much more reasonable commanded vrate. The commanded roll rate oscillated quite a bit and it is hard to visually extract any data from this loop.
NexSTAR-2 Flight 2
Flight Time: 33.80 mins
Autonomous Flight Time: 28.18 mins
At the start of the flight there was a slight issue with AODV working for the tracker laptop, and some time was spent fixing that problem before the deployment could commence. Around 5 miles the 802.11b suddenly cut out, and it was later determined that AODV was the cause of the problem. Otherwise, the flight went as expected.
Once again the vrate loop showed marked improvement. Unfortunately its hard to discern whether or not the other loops needed adjustment with the strong head winds, but the throttle rate was changing significantly to hold altitude.
The radio managed to maintain an ACK ratio of near 100% even at the furthest extent of the flight (10km). I suspect that with an automatic pointing antenna, the RSSI would be around -79 dB at that distance. An interesting artifact can be seen at around 5km where both the RSSI and ACK ratio dropped significantly both on the way out and on the way in. I'm not sure what exactly happened there, but perhaps the UA crossed a directed beam from some other communication device in the area.
The meteorology data seemed to reflect what the tracker vehicle reported as far as traveling in and out of rain bands. Once again temperature had a strong correlation with altitude, and humidity seemed to give a reasonable value. The pressure data was terribly noisy, and should be replaced by the Piccolo data as it uses a probe to eliminate most of the effects caused by the monokote, etc.
NexSTAR-2 Flight 3
Flight Time: 34.22 mins
Autonomous Flight Time: 29.90 mins
This flight was largely successful in the case of operational efficiency and radio communications. Before even completing a full orbit of the initial flight plan, the plane was already tasked to track the tracking vehicle. The vehicle left shortly thereafter and kept the plane at maximum ground speed all of the way to the turn around point. The communications remained at a reliable for the entirety of the experiment.
Communications with the plane showed an odd dip at about 5km again, but maintained an acceptable level throughout the flight. The turn around was forced because of flight time and available COA flight space rather than signal level.
The meteorology data needs to be compared with the radar data before much can be said. In the interest of generating a bit of a profile, the UA was briefly commanded to a lower altitude while on the way back to the trailer. An odd artifact in the wind data was noticed and is shown in the last plot. The UA enters from the South-East and the wind estimate turns until the estimated winds are almost entirely out of the East. Then, when the UA begins its orbit, the direction immediately changes back to being from the North, which is echoed throughout the remaining visible data. This is either the result of a bad estimate from traveling too straight of a path, or actually a gust.
NexSTAR-2 Flight 4
Flight Time: xx.xx mins
Autonomous Flight Time: xx.xx mins