V-22 Osprey Project - Tuning and Setup

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ESC SETUP

I used two Castle Creations Talon 60 ESCs for the V-22 Osprey.  These ESCs are high-quality with an electronic governer designed for RC helicopters.  Other ESCs with this feature are recommended.  Using the CastleLink software and USB dongle, I set the following RPM parameters:

Throttle Setting 2-blade 3-blade
20% 2600 2000
70% 2600 2200
100% 2800 2400

As with any standard airplane or heli it's important to calibrate the ESC endpoints as well.


TILT SERVO SETUP

The HiTec D85MG servos are digital high-torque metal-gear servos that are programmable.  Using the HiTec programmer, I set the 1000us endpoint to the forward flight (0 degree) position and the 2000us endpoint to the hover (90 degree) position, with the 1500us center point in the middle (45 degrees).  The programming of the servo is a bit challenging, as the endpoints set in the programmer coordinate roughly to 900us and 2100us.  It takes a bit of fiddling to get the 1000 and 2000us endpoints spot on.  I used an digital angle meter to set these positions on each wing rotor.


HELICOPTER SWASHPLATE

As with any standard helicopter, it's important that the swashplate be level when the servos are at their neutral position.  There are many tutorials on how to do this, so I won't go into this procedure here.  In addition, the blade pitch must also be set.  This takes quite a bit of back and forth tuning between the radio pitch curve settings, the dRehmFlight VTOL flight controller, and a digital angle meter.  For the full-size Osprey, the rotor blades are curved and have a 45-degree incidence at the root.  I am still using symmetrical "3D" blades that are common with sport RC helicopters.  There are curved, scale versions available, but that's for a later time.  I setup a single pitch curve with the following parameters.  As further testing proceeds, I may alter this depending on forward flight performance.

Pitch Curve Blade Pitch
-100 (1000us) -3 degrees
0 (1500us) 8 degrees
100 (2000us) 20 degrees

It's important that the mechanical linkages be as close as possible so that servo response is balanced across the rotor heads.


FLYING CONTROL SURFACES

As with any airplane, it's important to center the control surfaces.  The settings in dRehmFlight VTOL allow a trim setting to center the servo in forward flight as well as a flaps position when in hover.  With the controller in FF mode, set the parameters so the ailerons are centered along the wing.  Then switch to hover mode and set the parameters so that the flaperons are both extended down the maximum possible while being equal.  You can use a ruler to measure the deflection to ensure they are as close to the same as possible. 

For the elevator, perform the same process with the flight controller trim value to center the elevator and ensure equal throws to each side.



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