Difference between revisions of "Unequal Collective Pitch"

Revision as of 19:54, 10 December 2017

If you are struggling with achieving equal Collective Pitch range for positive and negative side, then the following procedure is for you.

1 Transmitter

First it is important if your transmitter was configured correctly in terms of channel travel range. It can be verified in the following way. Start the Spirit Settings and go to the Diagnostic tab.

1.1 Collective Centering

1. Put your Pitch stick at the center as close as possible.
2. Verify what value you can see in the Diagnostic tab at the Pitch bar.
3. Make sure you will see 0%. If value is different by more than +/- 2% it is recommended to use the Subtrim function in your transmitter and adjust Pitch channel to achieve 0%.

1.2 Collective Pitch Low and High position

1. Make sure that your Collective Pitch curve in the radio is configured to be -100% to 100% (Linear curve). NOTE: In some radios the lowest position starts at 0% but this is not a problem.
2. Put your Pitch stick at the lowest position - at this point you have to see -100% in the Diagnostic tab at the Pitch bar. If value is diffrent by more than +/- 2% it is recommended to check your
3. Do the same verification for the highest position - at this point you have to see 100% at the Pitch bar.
4. If this point are correct and you can see +/- 100% then your radio is configured correctly and you can move at the mechanics configuration.

2 Mechanics and Geometry

Correct configuration is important to achieve good flight performance. Especially for beginners it could be unclear what are correct steps to do this well. If steps are performed in a wrong way it will usually lead to an incorrect configuration. Correctly you have to start with servo adjustment and go up step by step until you will reach blade holders. After each completed step do not touch what was configured previously.

1. Move to the Servo tab and there toggle the Subtrim (tuning) - in this mode servos should be locked exactly in the center. This mode is recommended to be enabled each time you are configuring mechanical center of anything, including 0° between main blades.
2. Set all servo arms as close to the center as possible - (usually perpendicular with respect to servo case) - this should be done with Subtrims in the Spirit Settings (when Subtrim tuning is enabled).
3. put push rods/ball linkages perpendicular (as close as possible) with respect to servo arm and swashplate - in some models it is unfortunately not possible which always mean error, but you as pilot can't do much about it sometimes. (when Subtrim tuning is enabled).
4. adjust 3 push rods to the same length (if model is constructed in this way). If not, then it adds usually another imprecision to the geometry. But again you can't do much about it. At the same time achieve position where swashplate is in the center of its collective pitch travel and at the same time to be perfectly level with a cyclic leveler. This mean to change length of all 3 rods equally (always). (when Subtrim tuning is enabled).
5. mount the rotor head and change length of 2 upper push rods that are connecting blade holders so that they are again equal and at the same time they are configured to be at 0°. This mean when you put there a main blades and fold ends together, they must be exactly at the same level. And this level should be held at any angle/position/rotation of the main shaft. If not, usually swashplate is not levelled correctly or there is a big play in the mechanics.
6. At this point, if manufacturer of the model designed it correctly and your servos have equal servo travel, then you must achieve always same collective pitch travel in both direction. If not, then go to the Servos/Servo Travel Correction and move with a sliders (usually it is enough to move with all 3 values by same amount). When done correctly, you will get perfectly precise angles.