Long-term Memory

Place: Halle
Tanks flown: 4
Time flown: 1h00 (cumulative model timer: 28h56)
Rx battery recharged with: 1373 mAh (but more than 2 hours after the last flight)
Tx battery recharged with: 459 mAh
Glow heater battery recharged with: 193 mAh
Starter battery recharged with: 30 mAh

Comment:
Another beautiful day at the field, although the wind was gusty.

Practiced autorotations a lot. I’m mostly following this guide: try to land with less and less power available. I started out at 30%. The last attempt was at 15% power.

I’m a bit surprised how rough you can land the Raptor 50. Just make sure that you don’t have sideways or backward motion, as it might tip over or bend the tail boom.

Continue reading ‘Flight log 2008-09-28’ »

Place: Halle
Tanks flown: 3
Time flown: 0h46 (cumulative model timer: 27h56)
Rx battery recharged with: 221+800 mAh
Tx battery recharged with: 470 mAh
Glow heater battery recharged with: 430 mAh
Starter battery recharged with: 115 mAh

Comment:
Very nice weather: around 20°C and blue skies. Hardly any wind at first, but it got stronger during the afternoon.

First flight was mostly tuning the new rotorblades to get them to track correctly. I adjusted a total of 3 turns to get it to an acceptable level. The black blade still is a bit low, but probably only 0.5 turn or so.

The Rx battery had the same problem as before. I’m guessing it is still warm from the flight. I’ll try to recharge it later.

Other flight where mainly to get some footage from my FlyCamOne2. There is still a big “wobble” all over the screen caused by the vibration, but it’s a lot better than the previous attempt.

Continue reading ‘Flight log 2008-09-27’ »

Place: Halle
Tanks flown: 0.3
Time flown: 0h07 (cumulative model timer: 27h10)
Rx battery recharged with: 1665 mAh
Tx battery recharged with: 583 mAh
Glow heater battery recharged with: 561 mAh
Starter battery recharged with: 148 mAh

Comment:
Same weather as yesterday. I mounted my FlyCamOne2 and wanted to give that a try. Somehow, it managed to record 122 pieces of video instead of the 2 shots I planned. I glued the pieces together, but the result is “jumpy”, the quality is bad, it shakes like hell and is overcompressed, but just in case you still want to watch it: 2m18s, 13.7MB (x264 video, ogg-vorbis audio, matroska container, VLC plays this just fine).

After 2 minutes of flight, I suddenly hear a loud “tack”, but didn’t see or feel anything strange. I landed the heli promptly anyway to do a full check. The sound was fairly loud, since the heli was at least 100m away and was clearly audible. I checked the main and tail-drive gears, but none of them showed any damage. The rotor looked OK as well, until I examined it a bit closer:

The plastic foil at the top-tip of the blade somehow got loose and teared. This tip was traveling at around 430km/h (67cm from the axis, rotating at 1700rpm), which makes a lot of noise when something hits this wind.

Just swapping the blades with the spare (wooden) blades had my bird ready to fly again.

A few months ago, I got the FlyCamOne2 as an add-on for my Raptor. The manual mentions that the recording can be started and stopped electronically. With some additional electronics, it should be possible to start/stop the camera from the ground using one of the free channels on my remote.

The free channel can’t be used directly: the receiver sends out pulses of different lengths (between 1ms and 2ms), while the FlyCamOne2 needs a simple short to start recording. Some electronics will be needed to convert between these two.

After some googling, I found the CurveRC FCO2 I/F which does exactly that. But there are some downsides:

• It consumes a lot of power (10mA on 5V)
• Isn’t cheap (£10, plus international shipping, at the time of this post)
• I don’t get to enjoy myself figuring out how to do this myself

The CurveRC print seems to be build around an Atmel Tiny25 microcontroller, which is an 8bit RISC processor with 2K of build-in flash. Using a microprocessor makes the design fairly simple since nearly everything can be done in software. However, it must be clocked at reasonable speed to do something useful. This explains the fairly high power consumption.

So I decided I could do “better”.

Continue reading ‘Convert PPM signal to digital’ »