Phil Cole
Veteran
Location: Redwood City CA
| I've still got a PI in one of my models somewhere.
I never use it in normal mode since I can never be bothered to adjust the tail linkage to trim it.
However, I suspect that the overtravel in normal mode is something they did so you didn't have to set the rudder rate in your transmitter way up to get decent yaw rates.
The rudder input from the receiver to the gyro only controls yaw rate in HH mode. In normal mode, it controls rudder servo position, as with any non-HH gyro.
Normally, with normal mode gyros you set the rudder travel in the transmitter so the servo will over-travel on the bench. In the air, the feedback from the gyro as the model yaws will reduce the servo travel, keeping it within the mechanical limits. In this case, if they didn't boost the travel, you would have to change rudder rate when switching modes. I would guess that the amount of boost is not enough to cause binding when the model if flying.
You could try marking the pushrod with something that rubs off where it goes through a guide and see how much get rubbed off in flight when you give max. rudder input if you are worried about binding.
With the Arcamax PI 2700, you adjust the length of the servo arm in HH mode to stay within the mechanical limits of your tail rotor. There is no travel adjustment in the gyro. |
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To get the servo to respond to stick deflection close to the stop, I have to turn the ATV's down to 65%. I am running an Airtronics Infinity 660 with airtronics fm reciever, all the pinouts for the gyro plugs and servo plug have been properly changed to match. The gain pot on the gyro is set at 75%, the gain in the radio is set at 60%. The toggle for the 2700g servo is set to normal not 2700. I haven't flown this setup yet, so I don't know if it behaves properly in the air. The gyro came out of a Baron S with a 2700g servo and was working properly, though this particular issue was not specifically checked. Any insight would be appreciated. TIA
