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Other › 401 gyro - drifting in idle2 mode - wierd
10-08-2005 12:07 AM  12 years agoPost 1
hikscub

rrApprentice

California

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I just installed a 401 and it does hold very well - much better than my older gyro.

But I've got a wierd problem. I've got Idle1 set up for non-inverted flight in HH mode (70%). I've got Idle 2 set up for 3d in HH mode (70%)

The problem is when I switch from idle 1 to 2 the tail starts drifting. It's almost like some trim was added or maybe that HH is off.

So, this happens on my TRex cpm and the exact thing happens on my friend's Eco8 whcih has a 401. So there's nothing wrong with the gyro or heli. He uses a Hitec Eclipse7, I use an Optic6.

Anyone know what's going on?

Thanks

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10-08-2005 12:22 AM  12 years agoPost 2
dgshaffer

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New Jersey

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Reading your post at first I thought you may have some trim set up in idle-2 without knowing it as all 3 modes have seperate trim settings. It sounds like you've checked that though.

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10-08-2005 12:38 AM  12 years agoPost 3
MikeInMobile

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Mobile, Alabama

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What is your headspeed in each flight mode. If you did not setup your gyro in rate mode, you may have this problem. As headspeed increases, so does tail rotor speed. As tail rotor speed increases, less tail pitch is required to generate a specific amount of thrust. If the machine was not setup in rate mode, the Head holding logic may be able to compensate at lower head speeds, but may not be able to generate enough tail force when the head speed is increased. This is a common issue with head holding gyros when they have not been properly setup (most people do not bother setting up a head holding gyro in rate mode since they will never use it in this mode, but the rate setting are important so that the head holdong logic can compensate whenever the head speed increases).

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10-08-2005 01:33 AM  12 years agoPost 4
hikscub

rrApprentice

California

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Mike,

By setup do you mean making sure the heli works well in rate mode (servo trim, etc.)? Or do you mean initializing the gyro in rate mode and then switching to HH by rapidly switching from rate to HH three times?

My other HH gyro did not have this problem. It didn't hold nearly as well as the 401 but it worked the same in idle 1 and 2.

At this point I'm still getting the trex set up so I actually run the same headspeed (about 2400) in all modes.

Oh, also, the drift is nose right meaning the gyro is overcompensating against the rotor torque.

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10-08-2005 01:39 AM  12 years agoPost 5
MikeInMobile

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Mobile, Alabama

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All of your mechanical setup should be done with the gyro in rate mode.

Setup your 401 as described below:

1> Apply power to your heli with the gtro in HH mode and adjust the sub-trim si that the gyro does not "seek" when the trim is neutral. This is your baseline.

2> Switch your gyro to rate mode and test fly your heli. Make mechanical adjustments (slide the tail sero) so that the tail holds with the trim lever centered (this is the rate adjustment)

3> Now, switch the gyro to HH mode and adjust the trim (slider on the radio) so that the tail holds .... this is your HH trim setting.

Using this type of setup allows the gyro to hold the tail with little or no effort and will increase the effectivenell of your gyro (will keep the gyro from fighting the mechanical setup).

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10-08-2005 12:37 PM  12 years agoPost 6
Gary Hoorn

rrKey Veteran

Annapolis Maryland​USA

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3> Now, switch the gyro to HH mode and adjust the trim (slider on the radio) so that the tail holds .... this is your HH trim setting.
I would not recommend moving the trim in HH mode. You are telling the gyro to seek a new neutral. Trim the Heli in Rate Mode with the trim lever and subtrim centered. Get it close by adjusting the linkage and not the trims. Arm the Heli with the gyro in HH Mode and do not move it until it initializes. Lift into a hover. If the tail drifts you have some other problem.
Gary

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10-08-2005 04:19 PM  12 years agoPost 7
MikeInMobile

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Mobile, Alabama

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Actually, you WANT to offset the neutral in HH mode. This helps the gyro to compensate for torque induced shifts. Typically, a 401 gyro required very little or no offset to operate flawlessly. When using a cheaper gyro, like the Align unit, this offset is typically greater. The problem is that if you do not setup your gyro in rate mode, you will ALWAYS have an offset neutral, which causes drift when the torque on the head changes. A general rule to remembler is that Rate changes are made mechanically, and HH changes are made electrically.

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10-08-2005 08:42 PM  12 years agoPost 8
hikscub

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California

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Ok, I played around with things and have a bit more info.

Seems that when I switch between modes the gyro goes into normal mode even though both modes are supposed to be hh. It doesn't like to switch between hh modes. I guess it's thinking something changed and it wants to reset.

So the drifting I was seeing was because I was in *normal* mode and the trim was a bit off. I *thought* I was in hh mode because the 401 is so good at holding in normal mode.

How do folks switch into a 3d throttle curve then and get into hh mode? I can't plug in the battery in 3d because the throttle will fire right up.

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10-08-2005 09:54 PM  12 years agoPost 9
Helis_R_Fun

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Brandon, WI USA

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Disconnect the Motor......plug in battery and go into mode to see what is happening....

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10-08-2005 11:18 PM  12 years agoPost 10
RandyT

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Los Angeles, CA

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Is you channel five set to the same switch as your idle~? Just a thought. Good luck.

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10-09-2005 02:39 AM  12 years agoPost 11
hikscub

rrApprentice

California

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I can select hh on any idle setting by setting the gyro percentage. The problem is that switching between idle modes that are supposed to be hh (same percentage - about 80) turns off hh.

I guess other folks aren't having this problems?

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