©2008 Skookum Robotics, Ltd
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How to Check Cyclic Pitch & Phasing
The goal of mechanical and gyro swashplate setup is to get your normal collective
blade pitch range, and a
cyclic range of about +-10 degrees,
which means a total
range of 20 degrees.
This is important.
(Cyclic pitch is blade’s pitch due to aileron
or elevator input)
The rotor blades must also have the correct
phasing.
This means that aileron and
elevator control input change each blade’s pitch at the correct time. For most
mechanical setups, the phase angle will not need adjusting.
While checking for good cyclic throws, phasing, and even swash motion, the
gyro must be put in setup mode, by pushing the mode switch towards the gain
dials
(see Section 8).
While in setup mode, all stick motions are sent directly to the swashplate as if
stability gains were all zero (the gyro only does its mixing function). The gain dials
and gain fields in the PC software will have no effect in this mode.
To check the cyclic range and phasing:
1)
Set collective pitch to zero.
2)
Align a blade along the fuselage, pointing over the nose of the helicopter as in
the photo below:
3)
Now try full nose-up elevator control, with aileron centered. Measure the pitch
of the blade that points over the nose.
4)
If the mechanical setup is ideal, the blade should not change pitch. If it does you
will need to adjust the phase angle, either mechanically at the swashplate or
using the gyro’s USB interface. If the pitch becomes negative adjust the phasing
clockwise (+), if positive then adjust it anti-clockwise (-).
Note:
this will give
©2008 Skookum Robotics, Ltd
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you normal phasing (90 degree lead); multi-bladed rotors may fly better with
some positive phase trim.
5)
Try full right aileron control, with elevator control centered. The blade’s pitch
should be about -10 degrees.
6)
Try full left aileron control, with elevator control centered. The blade’s pitch
should be about +10 degrees.
7)
Align a blade at 90 degrees to the fuselage, pointing over the right side of the
helicopter as in the photo below:
8)
Try full nose-up elevator control, with aileron control centered. Measure the
pitch of the blade that points over the right side of the helicopter. It should be
about -10 degrees.
9)
Try full left nose-down elevator control, with aileron control centered. The
blade’s pitch should be about +10 degrees.
If the cyclic blade pitch range is changed, the gyro’s stability gains will need to
be changed as well.
For example, increasing cyclic pitch range by 10% is the same
as increasing the stability gains by 10%.
