Well, the weather over the weekend was fantastic, very light breeze and wall to wall sunshine, so I went flying.
I have flown the big 'un exactly twice since I built it, the first time was a very short flight though. It lasted about 5 seconds and ended upside down in the mud, luckily with no real damage. It turns out that the manual has a completely wrong valus for the center of gravity of the plane, putting it far to far back. I was a little dubious about it at the time, but my common sense was overridden by the feeling of "well, they're germans, they must know what they're talking about"
After that, I worked out the correct COG from first principles, and the second flight went very well. I carefully arranged to be the only one there so if it went pear-shaped again I could hide my ignominy from the public. It took off fine, gained height alarmingly rapidly, and I spent the next 20 minutes trying to get it back down safely!
After that the weather was horrible for pretty much all of december and january, so last weekend was the first time I've had to try again. I have to say, once you've managed to set things up correctly, that this model really flies very nicely. Once I've really got to grips with it and have made all the mods to fit the autopilot, medium format camera, stereo video cameras, stereo digital cameras, etc, it should produce some amazing photos. This will add up to about 1.8kg of payload, which it should handle easily.
The thing is a little awe-inspiring, actually. It's the biggest model I've ever flown, with better than a 2m wingspan, and it's really quite chunky as well. Very light though, at around 3kg ready to fly. The thing is right on the borders of turning into a real light aircraft from the aerodynamic standpoint, and flying it is quite different from most of the smaller ones. The takeoff looks particularly realistic compared to smaller models, none of this 'roll ten feet and go vertical' nonsense
That said it gets off the ground pretty fast. It's got loads of lift and I definitely overspecced the power system. It takes off at around half throttle, and flies around quite happily at less than 1/3 throttle. Full power is a bit frightening, the motor/prop/battery combination is capable of about 700 watts (more or less one horsepower) and this will make it fly at about 90MPH. It climbs VERY fast like this. However, since the power curve is more or less exponential, 1/3 throttle is less than 100 watts, much more efficient than any of my other models from a watts per kg viewpoint.
The motor is actually capable of over 1kw output power, which would be serious overkill. Impressive when you look at it, it's only about 45mm in diameter and about the same in length. Radio control models are certainly pretty impressive nowadays! It's quite amusing to tell someone you fly an electric model airplane, then show them something that could carry off a small child when they're picturing a 2 foot long toy
I should try fitting some sort of MP3 player inside it (the guts of an empeg would easily fit), and a powerful but light amplifier and speaker. I could have it playing Wagner while doing low flybys, like in battefield vietnam! I have actually been considering the possibility of making a 3-phase brushless motor controller that would superimpose MP3 audio on the switching waveform, so the motor would play tunes during operation
pca
I can work out most of the details from looking at the parts, but there are a few points I'd like to be sure of, as they're fairly structural ("You fool, that's a load-bearing decal").
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