Tuesday, January 02, 2007

flying qualities report: Micro Mosquito helicopter

I'm doing everything I can to procrastinate working on a paper. Part of the procrastination includes playing with a new toy, Radio Shack's Micro Mosquito radio controlled helicopter.

Yeah, I know, totally geeky. So sue me. I'm having fun playing with it till I can afford the ten grand it'll take me to get a real rotorcraft rating. :-)

The Micro Mosquito is an indoor radio controlled helicopter with counter-rotating rotors and pretty amazing engineering. It weighs maybe a hundred grams, fits on the palm of my hand, and has survived repeated, ahem, "rough landings" from as high as ten feet with no permanent damage, though I do occasionally have to pop a piece back in place.

Helicopters are, by nature, unstable. Most airplanes want to fly--take your hands off the controls and most of them will right themselves and keep going. In contrast, you have to fly a helicopter constantly. The MM's counter-rotating design makes it more stable than most choppers and particularly easy to hover, but you still have to stay on top of it. If it bumps something while moving, or you give it too sudden a burst of forward thrust, it can start swinging around the rotors like a pendulum. If it swings too much, the rotors will eventually bump into each other and you're looking at one of those "rough landings."

The MM doesn't have a vertical stabilizer, which means its directional stability isn't so hot. While flying forward, air currents or friction in the drivetrain might suddenly kick the nose left or right. You have to watch and correct for it, but correct fairly gently or it'll start swinging around like I mentioned before. Our house is a bit drafty, leading to occasionally rough flying conditions, especially near hallways. In fact, the MM will sometimes get caught in up-, down-, or side-drafts that I can't even feel, sometimes too strong for the rotor system to overcome. I've installed the included "for extra forward speed" kit to help punch through some of the drafty areas.

My only complaint with the toy so far is that there's sometimes some odd control lag. For instance, I might tell it to thrust forward, but the tail rotor won't respond for a second or two, and there's an occasional lag in throttle response. The lag can lead to pilot-induced oscillations, where I tell it to go up to avoid the couch, it eventually responds, and by that time I'm saying "no, too high," then later it starts coming down and winds up bobbing drunkenly towards the coffee table. I don't know whether it's in the control system or maybe we just have a noisy radio environment. Otherwise, it's been a blast buzzing around the living room, avoiding the air currents from the wall furnace, and trying to land it on the helipad.

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