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Old Feb 22, 2009, 01:05 AM
Fly Runaway Fans
United States, TX, Fort Worth
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OMG, it's the end of the world!

Late night flight Saturday, V4 came up stable in the same state of yaw trim it shut down in this afternoon. That's never happened before.

Yeah it's got a rate gyro, gain set a blade width below the twitch point. The yaw error is ~4 seconds per 90 degrees, slower than a rate gyro can notice. The TX trim point is very critical, +/- one click between dead on and drifting. And it typically goes from needing R trim at startup to needing L trim once hot.

Not this time. Occasional yaw drifts to either side throughout the battery cycle, but no overall bias and haven't touched the trim.

Been reading the Boeing/AA 757/767 manual at work. Calls for a log entry when a performance parameter changes suddenly for no known reason. Log entered.
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Old Feb 22, 2009, 02:46 PM
All flight is 3D.
various parts of NY
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Quote:
Originally Posted by arbilab
Late night flight Saturday, V4 came up stable in the same state of yaw trim it shut down in this afternoon. That's never happened before.

Yeah it's got a rate gyro, gain set a blade width below the twitch point. The yaw error is ~4 seconds per 90 degrees, slower than a rate gyro can notice. The TX trim point is very critical, +/- one click between dead on and drifting. And it typically goes from needing R trim at startup to needing L trim once hot.
Mine is exactly the same. When starting cold it needs considerable right trim. As it warms up (and as battery voltage drops) it needs considerable left trim. It was like that pretty much since I got it and coincides with what a lot of other LAMA owners claim. I suspect it has more to do with battery voltage than with motor temperature since it will also start requiring more right trim again right about the point where the battery runs out.


It's not much of a problem since I am used to correcting for the yaw drift It behaves the same on every flight so I know what to expect. If anyrthing it has improved my skills. I am finally getting the hang of flying over objects, a little bit of 3D, while correcting for yaw drift. All in all it's a nice stable, and easy to fly machine.
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Old Feb 22, 2009, 04:07 PM
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^^^^
Odd...when I start out I need full left trim and move to the right as I fly.
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Old Feb 22, 2009, 07:26 PM
Fly Runaway Fans
United States, TX, Fort Worth
Joined Jan 2009
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If I could see better and if the problem was worse I'd swap motors to see if the trim leaned the other direction over time. If the problem was worse, it wouldn't fit within trim range and that would be kinda annoying. And a little dangerous cuz when I get more than 90 deg off axis I tend to get disoriented ahd hit things.

Today, thought 3mph wind was low enough to go outside. Hey, they told me this was NOT a 3-D heli, but there it was upside down. Drat. VERY seldom calm here. Nothing broke, took back inside and finished the charge, at work now.
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Old Feb 23, 2009, 02:07 AM
Fly Runaway Fans
United States, TX, Fort Worth
Joined Jan 2009
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Late-night flight, 2 bat cycles. Yaw trim kinda wandering but within a narrow range, not like it was going from 1/3 right to 2/3 left. No 'crash' crashes. Flybar came loose once, but seems it shouldn't have at the time.

Doing precision maneuvering within a T-shaped 5x7 airspace surrounded with rigid objects. +/- 90 degree nose orientation. I'm still lost if it goes beyond that. Still dodging the heli's own turbulence and characteristic tendency to suck itself toward fixed objects.

Wasn't it Bernoulli who figured out that moving fluids exert less pressure than static ones? I'd have to google it to be sure. But the closer you get to a solid object like a wall, the more the V4 seems to want to hit it. Whereas it's relatively stable in the middle of the room.

Meanwhile I'm drooling over Belt CP. It's a leap from V4, but geez, it's like real only smaller.
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Old Feb 23, 2009, 09:14 AM
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Quote:
Originally Posted by arbilab
Late-night flight, 2 bat cycles. Yaw trim kinda wandering but within a narrow range, not like it was going from 1/3 right to 2/3 left. No 'crash' crashes. Flybar came loose once, but seems it shouldn't have at the time.

Doing precision maneuvering within a T-shaped 5x7 airspace surrounded with rigid objects. +/- 90 degree nose orientation. I'm still lost if it goes beyond that. Still dodging the heli's own turbulence and characteristic tendency to suck itself toward fixed objects.

Wasn't it Bernoulli who figured out that moving fluids exert less pressure than static ones? I'd have to google it to be sure. But the closer you get to a solid object like a wall, the more the V4 seems to want to hit it. Whereas it's relatively stable in the middle of the room.

Meanwhile I'm drooling over Belt CP. It's a leap from V4, but geez, it's like real only smaller.

I just got a 450 size cp heli and I love it...definitely a leap from coax but you seem like a smart guy.....you'll do fine

Btw...kept my coax too....love it too much to get rid of it....flying that thing is a piece of cake compared to the cp. Almost relaxing lol.
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Old Feb 23, 2009, 11:48 AM
Fly Runaway Fans
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Yes, quite, I want a bird with enough range to cope with a light breeze in the park. Does seem the only way to get that range is take away the lag and stability inherent in coaxes. But correct me if I'm Chinese (Wong)--Belt CP would be futile to operate in a 5x7 airspace.

I think before I buy (and risk destroying) something that elegant, I'd better get to where nose in the rear hemisphere doesn't = loss of orientation/control.
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Old Feb 23, 2009, 12:20 PM
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Yes....cp heli = outside operation...there is a vid of a guy flying a cp inside.......nice vid, but not recommended.
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