Monday, June 1, 2009

Don't fly into the sun!

I've just bought a new battery charger for my planes, and like the muppet that I am I managed to overcharge my NiMh 6-cell battery pack for my Aerobird Xtreme, causing it to vent. I had been inspecting the charging process every few minutes and it just so happened that I was standing there when I heard the telltale sounds of hydrogen venting. Not good, but after checking the voltage of one of the cells, I was happy that I hadn't destroyed any of the others thanks to that cell's voltage being exactly 1/6th of the total battery pack. But I thought I should go for a flight to check what run time I was able to get out of the battery, just as an test exercise (and possibly an excuse just to go flying!).

It was late in the afternoon before I managed to get out to my "field" (an unfinished new estate development with roads but no houses), and the sun was very low in the sky. I hand launched the Aerobird into the wind - not facing the sun at this point - and went to perform a circuit around me. Unfortunately, I then made the fatal mistake of getting my Aerobird between me and the full glare of the sun. And right at this point, the wind gusted and cause a bank to the left. By the time the plane was out of the sun glare, it was downwind from me, heading into a dive, and I couldn't tell what direction it was heading!

Now before I go on, I need to explain one of the biggest problems with the Aerobird Xtreme - it's shape! The tailboom, the V-tail, and the wing shape all combine to create a plane whose direction in relation to you is very difficult to determine. You can literally take your eye of this plane for a second and look back only to find your brain thinking "hang on it wasn't facing that way a second ago!".

So now that my Aerobird was banking and I couldn't tell what direction it was facing, I fed the wrong input to the rudder and only made the bank worse to the point where there was no more lift and a crash began. I reacted with up elevator and managed to initiate a recovery, but I still did not know which direction she was heading. And when the wings dipped again, I again reacted the wrong way. This time I was so low that she just nosed over into a dive and my up elevator only served to shallow out the angle with which she smacked into the ground.

There was only minor damage which was repairable - as is usually the case with the Aerobird - but it served as a reminder that all of my reaction skills are still concious efforts rather than unconscious muscle memory. And that means I still have a lot of learning to do.

Seeing as I was out there to test the battery capacity, I repaired the 'bird and went out again yesterday afternoon. This time, I avoided going anywhere near the sun and instead spent the time doing simple circuits and landing practice. Even during this, there were a few times where I just lost the mental image of the direction the plane was heading and had to override what my eyes were telling me with what my brain "knew" the plane was doing last. To say these moments are an intense mental battle is an understatement, and I am sure experienced RC pilots will attest to mastery of this battle as a critical skill needed for consistently safe flying.

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