The next job is to build the undercart and main frames. This is pages 6/7/8
of the supplied manual.
The main gear is in bag HB, undercart in bag HF2,. The main frames are
in bag HB2, tail pulley in bag HB3 and the elevator rocker in bag HB4.
First step is to build the undercart and assemble the main gear. This is
very straightforward, the main gear one way bearing should be given some
lubrication, I use a light teflon based oil. The undercart should be assembled
but do not CA the undercart until you have lined it up with the assembled
main frames to make sure the distance between front and back skids is correct.
Next is the assembly of the main frames. I place the right hand frame on
the table and then place all of the various components into there respective
positions. Once everything is in place put the left main frame on top and
screw it all together. Don't use R48 on the main frame bearings or tail
pulley bearings a thin application of CA is much better.
When placing the elevator control arm link into the frames make sure it
is the correct way round so that the ball link will fit onto the swashplate
without excessive force. The ball link is keyed to fit one way. I also
always screw on the canopy fixing bolts before assembling the frames as
it is hard to do up the screws after the frames are assembled. Before installing
the tail pulley check to see that the top belt drive pulley is secured
properly on the shaft. If not epoxy it back on.
The next step is again relatively simple and is the build up of the pitch
control arms that connect to the servos. These then screw onto the sideframes,
again not too tight as they need to move freely. Bottom right is the anti-rotation
guide for the swashplate which is secured by two screws to the top of the
main frames.
Once the above items are built up the elevator mechanisms bearings and
elevator control lever can be installed. Followed by fitting the above
components to the mainframes. Below are pictured the elevator bearings,
these should be mounted with the short edge of the plastic facing downwards.
If you look at these bearing holders you will see they are not symmetrical,
by mounting short edge down the bearing is more central in the slot. See
pictures below :
Below are pictures of fitting the antirotation guide and cyclic / collective
pitch control arms :
Now the head assembly and main gear can be installed into the main frames.
Don't forget the spacer which goes on top of the main gear, also make sure
the locking collar is in position on the main shaft. Insert the mainshaft
down through the main bearings and through the main gear. Secure the shaft
in place by putting the screw through the main gear and tightening it up
with a nut on the other side. The whole helicopter should now be suspended
by the head and the locking collar pushed down onto the top main shaft
bearing and the grub screw tightened up (with some application of loctite
243). This then holds the main gear static and unable to move vertically,
there should be no vertical play in the shaft at all. If you don't have
an indent (narrower part) in the shaft that the locking collar is locating
onto then your main shaft is upside down and needs to be turned around.
The swashplate anti-rotation pin can also be fitted at this point in the
build.
