dkshema
rrProfessor
Location: Cedar Rapids, IA
| What radio -- this is a CCPM setup, I presume -- 3 servo, 120 degree swash control.
You need to plug the three servos that move the swash into the correct channels on the RX, you need to enable 3 servo 120 degree mixing in your transmitter, then you need to get the directions set correctly for the three servos individually, and when you get THAT correct, you need to make sure the three servos work together to give you the correct movement when you move the sticks....
...Here is a generic, step-by-step process that works every time to get your swash moving correctly:
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Enable the 120 degree, 3 servo CCPM feature in the transmitter before you do anything else.
Once you enable the CCPM feature, you should then be able to select 120 degree CCPM mixing, and the SWASH menu should be available to set the mix percentages for elevator, aileron, and pitch.
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The three servos will plug into the AILERON, ELEVATOR, and AUX 1 (PITCH) locations of your receiver.
Channel 2 is AILERON for a JR/Spektrum system
Channel 3 is ELEVATOR for a JR/Spektrum system
Channel 6 is Auxiliary 1, and also happens to be the COLLECTIVE PITCH servo channel for a JR/Spektrum System
Channel 1 is AILERON for a Futaba system
Channel 2 is ELEVATOR for a Futaba system
Channel 6 is Auxiliary 1 for a Futaba system, and also happens to be the COLLECTIVE PITCH servo channel
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Generic 120 degree CCPM swash control setup:
Whatever brand radio you use -- the receiver plugs are most likely labeled Aileron, Elevator, and AUX 1 -- the collective pitch channel.
Plug your servos into the correct channel on the RX. You have three servos controlling the swashplate. One servo connects to a ball that is either on the front or the rear of the swash and on the heli's centerline. The servo controlling this ball plugs into the ELEVATOR channel of your RX.
The remaining two servos connect to the remaining two balls on the swash which are 120 degrees apart. One will be on the left side of the heli, the other on the right side. These connect to the AILERON channel and PITCH channel of the RX. It doesn't matter which servo plugs into which channel, as long as one goes to AILERON, the other goes to PITCH.
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Set all trim settings to zero, no trim in any direction.
Go to the SWASH mix menu, and set ELEVATOR, AILERON, and PITCH numbers to +65.
This is only a starting point, we'll fix the SIGN of the number (+/-), and the SIZE of the number (bigger/smaller) later on down the page.
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Ignore the direction of the servos for now. We're about to fix that:
Two servos in CCPM mix work to tilt the swash left and right (the servos plugged into the AILERON and PITCH channels of the RX). This is the AILERON function. The third servo (plugged into the ELEVATOR channel on the RX) must NOT move at all when you move the stick side to side.
For ELEVATOR (fore/aft) control, all three servos work to tilt the swashplate fore and aft.
For COLLECTIVE PITCH, all three servos work to move the swash up and down.
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Go to your servo reversing menu in the TX.
Move the AILERON stick to the right. The servos plugged into the AILERON and PITCH channels must move in opposite directions -- one must move UP, the other must move down. If they both move up, or both move down, reverse the direction of only ONE of them (AILERON OR PITCH) at the transmitter channel reverse menu. It doesn't matter which one at this point.
Don't worry if they don't seem to move the swash in the correct direction at this point, just make sure that they go in opposite directions when you move the stick left and right. You only need to reverse one servo, as the point here is just to get one to go up, one to go down at the same time.
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Now, move the stick for fore/aft cyclic. The servo connected to the ELEVATOR channel on the RX needs to have its direction set so that when the PITCH and AILERON servo move UP together, the ELEVATOR servo moves down (and when the ELEVATOR servo moves up, the other two move down). Use the ELEVATOR reversing function in your TX to make this happen. Don't touch the reversing for the AILERON and PITCH channels.
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At this point, the swash will tilt left and right when you move the AILERON stick, it will tilt fore and aft when you move the ELEVATOR stick, and it will move up and down (while remaining level) when you move the THROTTLE/COLLECTIVE stick.
The swash directions may be reversed at this point, but at least the servos move correctly with respect to each other.
Now to get the swash moving the right direction with respect to the stick.
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Move the AILERON to the right. The right side of the swash should tilt down. If it does, fine, move on the the elevator setting. If the AILERON control is reversed (tilts left for right stick), go the the swash mix menu and change the Aileron number from +65 to -65. Changing the SIGN of the number in the swash mix menu REVERSES the FUNCTION (in this case, Aileron).
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Move the ELEVATOR stick forward (away from you and toward the top of the transmitter). The front of the swash must tilt down. If it does, fine, don't touch anything. If the front tilts UP, reverse the ELEVATOR function by going to the swash mix menu and changing the ELEVATOR number from +65 to -65. Changing the sign of the number in the swash mix menu REVERSES the FUNCTION (in this case, ELEVATOR.
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Move the THROTTLE/COLLECTIVE stick full open (away from you, toward the top of the transmitter). You should get more positive pitch (leading edges of the blades tilt up). If the collective pitch function moves correctly, fine. If the collective pitch is backwards (you get negative pitch when you command full positive) go to the swash mix menu and change the PITCH number from +65 to -65. Changing the sign of the number in the swash mix menu REVERSES the FUNCTION (collective pitch in this case).
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Playing musical chairs with the servo reversing function at the same time you mess around with the swash mix will drive you nuts.
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With a linear 0 to 100% pitch curve, set your collective stick to its midway setting (middle). The three servo arms controlling the swash should be in the middle of their travel range. Due to the way the splines on the servo shafts are designed, you'll have to try different positions of the servo arms on the shaft to achieve this. In addition, you may also need to mess with sub trim to get the servo centered with the collective at its midpoint. The arms are either going to be horizontal or vertical, depending upon servo arrangement.
The swash should be horizontal, and perpendicular to the MR shaft. Adjust the pushrods supporting the swashplate to make this happen.
At this setting, your blades should have ZERO pitch, the washout arms and the pitch mixing levers should be horizontal. Adjust pushrods to achieve this setting. The pushrods up on the head generally go in pairs. Make each pushrod in a pair the same length -- follow the helicopter build instructions to get the proper length of each pair of pushrods.
The swash should be in the middle of its up and down travel distance at this setting. Adjust the pushrods supporting the swashplate to achieve this setting.
So, with a linear pitch curve, at mid collective, the swash is level, the servo arms are in the middle of their travel range, the washout and pitch mixing levers are horizontal, the swash is in the middle of its travel range and the blade pitch is zero degrees (check both blades and adjust as necessary).
At this point you can select the various flight modes you are going to use and customize your pitch curve settings to match the flight mode.
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Remember -- to get the servos moving in the correct direction with respect to each other, you use the individual channel reversing menu on the transmitter.
To get the servos moving together in the proper direction with respect to the STICK, use the swash mix menu. Changing the SIGN of the number REVERSES that function.
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If you need more overall COLLECTIVE pitch travel, increase the value of the number for pitch in the swash mix menu. If you need less overall pitch travel, decrease the value of the number for PITCH in the swash mix menu.
If you need more Aileron CYCLIC pitch, increase the size of the AILERON number in the swash mix menu. If you need less Aileron CYCLIC pitch, make the AILERON number in the swash mix menu smaller.
If you need more Elevator CYCLIC pitch, increase the size of the ELEVATOR number in the swash mix menu. If you need less ELEVATOR CYCLIC pitch, then make the ELEVATOR number in the swash mix menu smaller.
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TR setup:
At neutral, and neutral trim, the servo arm for the TR is vertical, in the middle of its travel. The bellcrank at the rear is 90 degrees to the tail boom as shown in the manual.
As for the RUDDER setup, when you command a RIGHT turn (will make the NOSE of the heli turn to the right), the servo must PULL the TR pushrod forward, toward the nose of the heli.
For Left turn, the TR servo must push the TR pushrod toward the rear of the heli.
Once you have the servo moving the correct direction, hook up the gyro. Pick up the heli and turn the nose to the LEFT while watching the TR servo arm. The gyro must command a RIGHT turn, pulling the TR pushrod forward, toward the nose. If it is backwards, and if the gyro has a reversing switch, change the direction of travel here. Go back and make sure the rudder stick still moves the servo in the correct direction.
Looking at the heli from its right side, nose to your right, tail boom to your left, the TR assembly turns COUNTER CLOCKWISE. The TR blade on the right is going UP, leading edge UP, control ball link on leading edge.
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* Making the World a Better Place -- One Helicopter at a time! *
Dave |
