Long-term Memory

Trex600 time flown: 0h02 (cumulative model timer: 2h21)

Another try with the Trex 600, another crash… and again related to the rudder. Right after takeoff, the tail was oscillating heavily (yaw-wise, ~7cm amplitude, ~3Hz). I recognized this to be a gyro-issue so I landed and reduced the gyro gain from 30% to 20% (Futaba-scale). This settings still had oscillations, but they were slower and wider. Further reducing the gain (I went down to 5%) further reduced the frequency (down to ~1Hz), but didn’t stop the oscillation. Also, it became quite unstable as well.

Cyclic was still too sensitive, but I wanted to fix the rudder first; which turned out to be a wrong decision. Next thing I tried was switching to non-heading-hold mode. As soon as I switched heading-hold off, the heli started a pirouette and ascended. I managed to get it back to the ground, but with the sensitive cyclic I got myself a ground induced unscheduled maintanance.

Continue reading ‘Flight log 2012-07-28’ »

My first spool-up went rather well. The wind pushed over the rotor quite a bit, but I read that until the 3GX is actually airborn, it can’t compensate for anything. So I gave the throttle stick a push and indeed, the wind was compensated away. The controls were very sensitive; too sensitive for my taste; so I landed and increased the expo on the swash to 30% (it was 15%). During the next spoolup, there was a sudden “tick”, accompanied by a kick of the tail. Right after liftoff, the heli was pirouetting like crazy. Luckily I only was ~20cm high, so just dropping the pitch to -2º was enough to get it back on the ground without any damage.

I double-checked the gyro direction, the control direction and the direction of rotation; all seem to be correct. Until I took a closer look at the tail rotor itself:

The tail rotor hub had moved 6mm from the end of the shaft, and the set screw was gone. Moving the hub back into position was hard, it was jammed fairly hard.

Place: Home
Batteries flown: 0.2
Time flown: 0h03 (cumulative model timer: 4h33)
Flight battery recharged with: (2) 2398 mAh (after full discharge)
Tx battery recharged with:

Comments:
My miniTitan was repaired and had a new ESC. Time for the first test flight. After a minute of hoovering, I shortly pushed full collective to check the governor. The headspeed dropped, not surprisingly since the governor is set to it’s lowest setting. So I pushed full collective again, to see if the governor is able to compensate.

Again the rotor headspeed dropped. The governor did compensate, but only the motor rpm increased, not the rotor’s… And then the ground intervened. I squeezed the remaining rpm’s out of the rotor to soften the crash, but it did hit fairly hard.

Continue reading ‘Flight log – 2010-07-14’ »

Place: Halle

Raptor
Tanks flown: 1
Time flown: 0h18 (cumulative model timer: 32h07)
Rx battery recharged with: 428+197 mAh
Tx battery recharged with: 548 mAh
Glow heater battery recharged with: 1246 mAh
Starter battery recharged with: 450-ish mAh (forgot to note down)

miniTitan
Flights: 0.5
Time flown: 0h06 (cumulative model timer: 3h23)
Heli battery recharged with: (2) balanced 2181 mAh;
Tx battery recharged with: see above

Comments:
Went flying after dinner, the wind had calmed down and the rain had stopped.

I had some trouble starting my Raptor (glow heater indicated only 1A instead of the usual 5A). Since it’s been a while since I charged it, the battery was dead. A few minutes at the charger solved the problem.

In the mean time, I took my miniTitan out. Did some flying back and forth and a few stall turns to regain confidence. Next I did some back-flips. This is where it went wrong. On my 3rd back-flip, I intended to keep the heli inverted for a second and continue the back-flip, but the ground intervened…

Continue reading ‘Flight log – 2009-07-25’ »