CCPM Swash Leveling
Setup a new model on your transmitter, either 120° or 140° swash configuration (140° is better if your heli supports it). Switch to idle up and set your pitch curve to a 50% flat line, this will stop you accidentally changing the pitch via the collective stick during the setup process.
Servo and Geometry
A servo horn will move the most when it is in the horizontal position and as it approaches the vertical the amount of throw is ever decreasing until it reaches vertical where there is no throw. If the servo horns that control the swash are not geometrically equal under fast control inputs you will get unwanted interactions as the servo horns are in different positions. For this reason it is important that the geometry that controls the swash is as perfect as possible before any other configuration is attempted.
The 3 linkages coming from the swash bell-cranks (or direct from servo) to the swash need to be exactly the same length as suggested in your heli’s manual. Otherwise for the swash to be flat the servos and/or swash bell-cranks will need to be in different positions which will cause interactions during fast control input.
With the transmitter on in idle up (should still be at 50%), position the servo horns/disks so they are as horizontal as possible. This may mean trying several different horn/disk positions. Note that servo orientations and geometries do vary so the important thing to remember is the bell-crank controlling the swash should be horizontal when the servo is at it’s centered position (or very close too).
Swash
Swash EXP is recommended and should be enabled in your TX swash setup. You need to enable this prior to setup otherwise it will effect your ATV and Subtrim. The effect of swash EXP is a smoothing effect to the swash motion.
There are now 3 basic positions that the swash needs to be leveled in; max-collective, min-collective and mid-collective. For this you will need a swash leveler, the best place to level first is the mid-collective as changes here will effect max and min collective positions. Your TX is still in idle up so you should be at 50% collective (remember your flat curve). Because you spent time getting the geometry right at mid-collective you should be very close to level, you should only need a few clicks of sub-trim on either the elevator, left aileron or right aileron to level the swash. Once leveling at mid-collective is complete you need to remove your 50% flat curve and replace it with a normal linear curve 0%-100% in idle up in order to level the extremes. With the collective stick at 100% level the swash using the same process as you did for mid-collective, but rather than using subtrim you will be using ATV (adjustable travel volume) or endpoint adjustments. Again if all is well it should only be a few clicks of ATV on either the elevator, left aileron or right aileron to level the swash. Repeat the process for min-collective (collective stick at 0%).
Note: The elevator swash ball is positioned (with a 120° CCPM setup) further away from the main shaft then the aileron swash balls. The effect is the elevator bell-crank needs to travel further to be at the same position as the aileron bell-cranks at extremes. The end result is the elevator ATV will need to be adjusted more than the aileron ATV at max and mid collective.
Assuming the 3 links connecting the swash bell-cranks to the swash are the correct length then now at mid stick your swash should be halfway in terms of the available travel on the main-shaft. If not then your 3 links are all too long or too short. However if you are halfway but you need more range (both up and down the main-shaft) then you need to modify the PIT percentage in your swash setup on you TX.
Testing
With the swash leveler on you should now be able to move the collective stick from 0%-100% and through-out the motion the swash balls/links should stay level and touching the leveler. Now to can be confident the swash will not cause any unwanted control inputs.
Related Posts:
Recent Comments