JKos
Elite Veteran
Location: City of California in the state of Maryland
| Here is a method I came up with that has helped a few guys.
Yes, turn on the "Expo" on the Swash Mix screen.
1) Set all the EPAs for the three channels which control the swash (2, 3, and 6) to 100. Set subtrims for channels 2, 3, and 6 to zero.
2) Obtain proper swash movement directions using servo reversing and the Swash Mix settings. First get the servos all moving the correct direction so that positive collective input moves the swash upwards. Then, if aileron or elevator inputs are backwards, negate the appropriate Swash Mix value to reverse that input's direction.
3) Set all the points (or just the middle three) on your Normal mode pitch curve to 50%. This insures that you are doing the next five steps at exactly 50% pitch when you place the collective stick in the middle (do that now).
4) Get the servo arms "square." Square could mean perpendicular to the main shaft or as appropriate to the geometry of the heli. This may take playing with servo horns to find the closest match and then using a bit of subtrim if needed.
Here is a method I use on push-pull setups.
 where A=A' and B=B'.
5) If your servo geometry is correct and a link lengths to the swash are all the same, the swash should be perpendicular to the main shaft or very, very close.
6) Eyeball the swash from the front of the heli. You are checking for perpendicular to the main shaft in the aileron input axis. Check and adjust this way first as adjusting this affects the elevator axis setting. If the swash is not perpendicular to the main shaft, adjust a link slightly to get it perpendicular.
7) Eyeball the swash from the side of the heli. You are now checking for perpendicular to the main shaft in the elevator input axis. Adjust the link at the rear or front of the swash if necessary.
8) Insure your blades are both at zero pitch and that the washout arms and mixing arms are perpendicular to the main shaft. Adjust links as necessary to achieve all three conditions at once.
9) Set your Normal mode pitch curve to go from 0-100.
10) Set the collective Swash Mix value (labeled PIT) such that the collective range is correct. I.e., if you desire + and - 10 degrees of collective, adjust the Swash Mix value to obtain that total swing. If your servo and head geometry are correct, you will see equal negative and positive pitch readings.
11) Position the flybar parallel with the tail boom. As you lower the collective stick, note whether the paddles stay at zero pitch. If they move, adjust the EPA of channel 2 or channel 6 as necessary to make the paddles stay level as the swash goes down.
12) Now raise the collective stick from center up. Again, watch the paddles. If they move, adjust the EPA of channel 2 or 6 as necessary to keep the paddles level.
13) Position the flybar perpendicular to the tail boom. Lower the collective stick and watch the paddles. Adjust the channel 3 EPA as necessary to keep the paddles level at full negative collective. Raise the collective and adjust the EPA of channel 3 to keep the paddles level at full positive collective.
14) The swash should now stay level as you raise and lower the collective.
To see if your swash is indeed perpendicular, rotate the head and watch the paddles. They should stay at zero pitch all the way around. Check for this at various collective positions.
15) Recheck your collective range and adjust the Swash Mix. It should have taken only small EPA changes and your collective range should not have changed much if any.
One can replace the eyeballing part and watching the paddles by using a method such as this:
Rotate the main shaft and take readings at the three control points.
These methods apply equally to any radio. Just replace the channel numbers, "EPA", and "Swash Mix" labels with what your radio calls them.
- John
MSH Protos |
