by Oops » Thu Sep 01, 2011 6:48 am
Now, this morning flight #3. I noticed that the 1300mA transmitter battery is ample for powering the 500mW 5.8GHz, camera and OSD. Recharging puts only 350mA back in (with lengthy dry testing before). Initial I didn’t think the flight was going to happen with a breezy Southerly but this suddenly died down. Clouds higher up indicated that the mountains probably blocked the flow at lower altitudes.
Took off from the estuary side of the island (where I had made the first out landing) and heading into the very light breeze. Soon found myself a few hundred meter up and a few hundred meter upwind. Amps around the 20A till into cruise down to 3-4Amps which gives me just over 30km/hr. Before I knew I was 800 meters away and signal was still good. I switched to auto altitude and kept on cruising. One of the two spotters had binoculars and could follow the flight for some time. The frontal (and tail) area of the phoenix 2000 is small though and easily lost. Lets see if a 1000meter still works. No problem, just the odd few second outage. 1100meter, 1200meter. I should have turned around I suppose but then thought, I have altitude, the tide is out so plenty of estuary to land on, heading into the wind, I can flick the RTL switch or the RC receiver failsafe (with RTL) will kick in.
So kept on going, passed both miles (~1500 and ~1800 meter) without too many seconds loss of signal. Past the 2000 meter and still good, 2100meter a long period of signal loss (~5 seconds) but then it got clear. The radio started to beep at this stage and so I decided to slowly turn without too much banking and got to 2250meter while still in control and good picture. Both spotters had lost the model which was now above the orchards and low hills of the mainland.
During the first 10 seconds or so of the return I lost the video signal completely but this soon cleared up. It does not take long to get to this distance (and back) so if you ever try this (and you will) watch your distance, battery levels and have enough altitude. Just in case you loose height and then loose your 5.8GHz signal.
Soon I (or more accurately the plane) was overhead and I headed to the seaside of the island which means flying over the high pine trees. I was about 200 meters away and down to less then 100meter and suddenly lost A/V signal for long seconds, too long to be comfortable. I switched to RTL and some grainy signal returned but to my horror I could just make out that the power stayed at about 3.5A despite full throttle to climb into better reception. The picture was only just good enough to see what was going on. The spotters yelled that the plane was in an unusual attitude which I could indeed spot with nose down and too much bank: likely stalled. For a second I contemplated to land on the beach but with the already poor signal that would not be an option. I managed to level and fly over the lower parts of the trees and soon had a good video again but still only just over 3 amps.
Cut the power, flaps on and a long final approach which was followed by a smooth and uneventful landing other then that it was an FPV one.
Back with the aircraft in my hand I check the temperatures of the A/V transmitter (cool), motor/battery (both not more then warm). The ESC is out of touch under the plywood (with enough room around for breathing). Again put on full power which still showed just over 3 amps. I had the 2200mA 3C battery recharged which put in 1400mA and produced full power after that.
Now, the important thing, what was the battery voltage during flight? I think still above 11v but cannot be sure. I tested it again about 30 minutes later and let the motor run a bit longer which dropped it to 10.5V but still low Amps. Did the 35A Waypoint ESC lower the output? In the instruction there is no information on this.
Again a lot of new tricks this old dog had to confront. As we know, and as this flight has proven, 5.8GHz is very useable as long as there is no obstruction blocking the signal. Don’t fly behind trees, buildings, hills. A/V signal will suffer quickly. Also keep the plane level when a long way away.
A few things on the agenda:
-I really need to record the flights so hopefully with the Jaycar A/V recorder I can document the information.
-sort out the loss of power problem, might put in the 30A Turnigy ESC which I have a programmer for.
-dedicate a switch to a certain power setting for cruise.
-still want to put the camera pan and tilt on but this will mean a fixed OSD setting and loss of flaps.
-tuffs on the wing and nose to follow aerodynamic flow condition and side slip. On a calm day this might give me stall speed.
-streamline the antenna and camera. Will plastic tape influence the signal?
-look into directional antenna, dual antenna, I don’t know. More trick to learn…