Chapter –XIV
Adjustments
( V-Stabi, rotor blades, throttle curves etc. )
Adjustment of the rotor blades
Now mount your rotor blades. Please note the following: If you use the recommended Rigid or Radix blades (length of 710
mm) with a blade root of 12mm you should use the plastic spacers added to the kit in any case but not any aluminium
spacers, because they jam in the aluminium of the blade holders and leave ugly traces.
Attention!
Irrespectively of which blades you use, it is important that the blades do not have an advance of more than 2mm
at the leading edge (to find out, let it hang down vertically from the mounting hole and check if the leading edge hangs
straight down or if it is tilted forward at the blade tip). Blades having a larger advance react very aggressively and add a great
load to the servos and the mechanics.
You may tighten the blade bolts 0138 so that the blades can still swing around, without much force. They should be tightened
just as much as necessary, to not swing down by their own weight, when holding the helicopter with the rotor shaft
horizontally. This is very important for the flight characteristic of every helicopter. Too tightly fixed rotor blades produce
vibrations and lead to a pronounced pitch-up tendency in high-speed flight.
Some rotor blade manufacturers use longer bushings, which extend above and below the blade root. Reduce the bushes with
a file down to the surface of the blade holders tighten the blades with pressure on the root and not on the bushings.
Otherwise a sensitive adjustment is impossible. Also, you should grease tightening area of the blades with blade roots of a
thickness of 14 mm, which are assembled in the blade holders directly without any additional washers.
It may occur that the lengths of the rods have to be adjusted differently to align the blades exactly to 0°. The reason for this
are tolerances of the blades or blade holders, that have to be compensated for.
Possibly you already have screwed in the ball link 0121b into the driving bush 0121a until it reaches the stop. However it has
to be screwed in further to reach 0°. So let it remain at a positive angle to a certain extent. Align the other blade
correspondingly and electronically trim the swash plate in the V-Stabi down to a small extent.
Make sure that the swash plate is not lifted off the lock when aligning the blades. Even a small gap on one side is sufficient to
faslify the result completely.
Due to the hard blades used nowadays an adjustment of the blade by track watching while flying is not reasonable, because
you do not see anything.
Experience shows, that a helicopter may vibrate in a hover while the track appeared to be perfect. A closer look revealed a
pitch-difference of 4° between the two blades. Being very accurate at this stage can spare you the necessity of doing it on the
field.
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At first put the 12mm thick swash plate lock 0394a below the swash plate
and push the swash plate to the stop. The main rotor centre hub has a flat
surface at the top, were you can put on a flat strip. The strip serves as
reference line to align the blades to a pitch of 0° at neutral position of the
pitch-stick. You only need two paddle-gauges, but no water level. Push the
paddle-gauges to the blade ends and look from the front over both gauges
and the rod. Now all three lines have to be aligned. If this is not the case you
can correct the connecting rods 0121a/b/c of the main rotor.
Attention!
A half
rotation at one of the ball links can be sufficient.
