ronbell

Greg - since my gyro experience is from helicopter applications I'll leave the other guys to provide recommeded gain settings for flight. I plan to intially set my gain to one of the side sliders on my 9303 until I find the setting that I like and then move that over to the regular gyro gain function in the TX. However, there are many ways to skin that cat and it really comes down to personnal preference and whatever you are comfortable working with. However, here are a few pointers about the gyro that might be helpful...

1. Like you I was initially planning to use a y-harness to combine the 2 rudder servos. Nothing wrong with that. I simply decided when running the wires through the plastic tube to the tail that I might as well run 3 instead of two, just in case mechanical matching of the rudders became tricky. This is definitely in the nice to have category and might well prove completely unecessary.
2. If you use the matchbox between the gyro and the servos then the gyro is not talking directly to the servos so the digital/analog setting is not important from the standpoint of damaging the servos. That setting controls 2 things... First, it changes the format of the signal from the gyro and the digital setting would burn up an analog servo if it was connected directly. Second, when set to analog it allows you to adjust the response time of the gyro to compensate for the fact that analog servos can't respond as quickly. In effect it lets you tell the gyro to wait a little to let the servo catch up. This is the purpose of the delay setting. However, having said that, this is really for helicopter applications where you are trying to lock the tail rotor response for a solid hover. For airplanes, using the matchbox approach, I would set the gyro for digital servos, set the delay to zero and forget about it.
3. The gain setting stuff is hard to explain until you get your head around the connection between ATV values, gyro gain values, TX gyro programming values, and the heading hold vs. rate mode settings. The first thing to understand is that a normal radio channel puts out a signal with an ATV range that is nominally -100% to +100%. In the gyro function in the 9303 that becomes a gyro SETTING of 0 to 100%. Hence 0% = -100% ATV and 100% = 100% ATV. It's really worth drawing a scale on a piece of paper to keep this straight!! Now when we start taling in GYROGAIN then there are TWO ranges; one for heading hold mode, and one for Rate (sometines called Normal) mode. EACH GAIN has a range from 0 to 100% with 0 being 'gyro switched off' and 100% being maximum gyro control. Let's take each in turn:

- Heading Hold (AVCS) mode - ATV values of +1 to +100% apply here, which equates to gyro function setting values of 51% to 100%, which equates to gyro HH GAIN values of 0 to 100%.

- Rate mode - ATV values of -100%to -1%apply here, which equates to gyro function setting values of 0% to 49%, which equates to gyro HH GAIN values of 100% to 0. NOTE that as the ATV/ setting value DECREASES the gyro gain INCREASES.

NOTE 2 things - The signal range goes from 100% gyro gain in rate mode (at the lower extreme) to 100% gyro gain in HH mode (at the upper extreme). NEVER send a gain control signal that is exactly mid-range (0 ATV) as the gyro will be unstable due to not being able to determine which mode it should be in.

A reasonable starting point for gyro gain settings is usually 50% gain ( -50% ATV or 25% gyro function setting) but you do want to always have a way to quickly turn the gyro to 0 gain (off) - if the gyro gain is too low then no harm will be done, but if it is too high then you might experience yaw ocscillations (rapid tail wagging).

4. Another thing to check before any attempt is made to fly is that you have the gyro DIRECTION set correctly. THIS IS VERY IMPORTANT. With everything powered up and the gyro in RATE mode (amount of gain doesn't matter) then first verify that the rudders respond properly to you stick inputs; right stick = right rudder and vice versa If they don't then you need to reverse the rudder channel in your Tx. Now, with the stick centered, turn the aircraft (or just the gyro) in the yaw axis and verify that the gyro moves the rudders to counteract the turning motion - if you turn the aircraft such that the nose turns to the right thaen the gyro should inject left rudder. If it goes the wrong way then you need to flip the DIRECTION switch ONTHEGYRO, not in the Tx.

5. Last thing I can think of right now is the range pot on the gyro. This control how far the rudder servos can physically move. Normally you control sevo range using the ATV settings in your Tx. When using a gyro things are done differently... You should set the rudder channel ATV values to +/-100% and leave them there for now. Next, again with the gyro in rate mode, you use the range pot on the gyro to adjust the the servo range such that maximum stick input gives the desired maximum rudder deflection with no binding in either direction. When using a gyro the ATV values in the transmitter really control the response speed of the rudder more than they do the actual rudder value. Hence, lowering the ATV would 'soften' the rudder response feel and higher values would make things more 'twitchy'. You can play with these values later if you don't like how things feel in flight.

I hope the above helps - it took me a while to get my head around the who gyro thing when I first got into helicopters so don't feel special in any way. Ask lots of questions until you are comfortable that you have things straight.

Ron.