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In which Ben fails at RC helicopters. - Adventures in Engineering — LiveJournal
The wanderings of a modern ronin.

Ben Cantrick
  Date: 2008-04-13 16:37
  Subject:   In which Ben fails at RC helicopters.
Public
  Mood:amused

So I wussed out and decided that it would take at least three weeks to get a new heli, while repairing the broken one would take a week. Impatience won out over anger (for maybe the first time in my life) and I fixed the Honey Bee. Today has been the first weekend where I wasn't busy and the weather didn't totally suck, so I took it out.

The first thing you need to know about the Honey Bee King II is that it's tail-heavy as hell. I think it was made for a much heavier NiMH battery, not the li-po that's currently in there. As a result, unless you mount the battery so far forward that it's actually falling out of the heli, it will do what I call the "tail pirouette". This is where the fin that prevents the tail rotor from hitting the ground digs in, and the whole heli spins around that point of contact. It won't take off because the severely rearward weight distribution means the whole heli would have to tilt backwards at something like a 45 degree angle before the CG would be under the main shaft. Suitable application of velcro will allow you to hang the battery far enough forward that the overall CG will be pretty close to the main shaft. The setup video on youtube only mentions this in passing, but it's a huge thing.

The second thing you need to know is that at least some of the HBK2s come from the factory with their gyro out of whack. But I'm getting ahead of myself.

Always respect the rotor disc. It certainly hits with more than enough force to take an eye out. If you ARE stupid enough to crash your heli into yourself, at least wear jeans so it won't leave you with multiple cuts and bruises. (Or, if you're into that sort of thing, then hey...)

Metal objects and wooden rotor blades don't mix. Or at least not very well. On the other hand, rotor blades are a lot cheaper than rotor heads, you know? ;] Basically the out of whack gyro led to a death spiral and the rotor disc hit this telephone junction box. The picture speaks eloquently for the end result.

http://www.gully.org/~mackys/heli-crash/MOV00005.MPG - My digicam is teh sux when it comes to video, but here is a short clip for your amusement. The camera wasn't running when I crashed, but this may still be fun for someone. The little speech at the beginning is: "This is my first heli flight. I'll probably crash and burn horribly. So this should be fun... for you, the viewer." and not "I have to go to the bathroom REAL bad! Oh, my bladder!" as you might expect from watching it. Then I just get the heli off the ground, and someone wants to use the sidewalk, so I have to put it back down and let her go past. Bah!
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  User: nickhalfasleep
  Date: 2008-04-14 01:17 (UTC)
  Subject:   Re: DSC00004.JPG
Epic Flail! Like the Spanish Inquisition!

Cheer up! With this sort of flight record you could at least get on with American, Southwest, or United Express! In maintenance or piloting!

R/C Aircraft are hard. R/C Helo's doubly so. I've heard it's harder than flying a real helicopter since you don't get the inertial feelings a real helicopter pilot gets.

Do they sell "motion control" rigs that are balanced enough to let you fly but not drop a helicopter by having it on an arm that can hold it moderately stable? Would a large indoor space work better than outside with the wind and air currents?

And why did you choose to fly an "unbalanced" helicopter? I'd assume you could balance it around the main rotor before flight, or does the mass behavior change in unexpected ways with the spinning rotor?

Just think, a few wiimotes and a small circuit, you could make yourself an R/C V-22 Osprey with computer assisted flight through the unstable regions just like the prototype.
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Ben Cantrick
  User: mackys
  Date: 2008-04-14 03:05 (UTC)
  Subject:   Re: DSC00004.JPG
Epic Flail! Like the Spanish Inquisition!

You should see it today. All the formerly red and purple stuff has turned black.

R/C Aircraft are hard. R/C Helo's doubly so. I've heard it's harder than flying a real helicopter since you don't get the inertial feelings a real helicopter pilot gets.

Twitchier, too. Small craft, low weight. Doesn't help that I'm flying a $150 cheap-ass one also. Frankly I'm surprised it took me three batteries worth of practice before I crashed it. (The leg swipes happened on the second battery, so I guess I did crash it on the 2nd battery too, it just didn't break the heli.)

Would a large indoor space work better than outside with the wind and air currents?

After flying today in the light and gusting breeze, I think the answer to that is HELL YES.

And why did you choose to fly an "unbalanced" helicopter?

Not unbalanced, screwed up gyro. I flew it that way because I didn't know the gyro was screwed up. That's the problem with being entirely new to this and not knowing anyone else who does it. I have to make all my own mistakes to learn the obvious.

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  User: (Anonymous)
  Date: 2008-04-14 02:36 (UTC)
  Subject:   weight?
how much weight do you need to balance it out? a kilo?

-l
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Ben Cantrick
  User: mackys
  Date: 2008-04-14 03:08 (UTC)
  Subject:   Re: weight?
Nah, nothing like that. The whole heli only weighs a little more than a kilo. You just need to velcro the battery in... well, I won't say "correctly". Strap it in way farther forward than you'd think possible.
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