Stabiliser Panels - GRAUPNER heim Bell 230 Instructions D'utilisation

Bell 230
1.7.2.3 Final installation of the tail rotor drive shaft
In the previous two sections you have temporarily assembled and installed the tail rotor drive
system, so you should now be confident that the parts fit correctly, and that you know their final
position. Withdraw the tail rotor drive shaft (B9) from the guide tube (B8), oil it lightly where it
runs in the bush, and slide it back in.
Apply a few drops of UHU plus endfest 300 at both ends of the channel in the channeled rail
(B6), and at intervals of about 60 mm along its length. Rotate the guide tube (B8) to distribute
the epoxy inside the channel.
Fit this assembly into the tail boom from the front, past the mechanics, as described in Section
1.7.2.2, until the drive shaft projects from the tail end sufficiently to be fitted in the tail rotor
gearbox coupling 4618.40. The shaft can now be fixed permanently in the coupling: remove all
traces of grease from the rear end of the tail rotor drive shaft (B9), roughen it by rubbing fine
glasspaper to and fro along it, then push it into the shaft coupling as far as it will go. Tighten the
grubscrews in the shaft coupling to secure it. Now unscrew the grubscrews completely one by
one, apply a drop of thread-lock fluid, No. 952, or bearing retainer, Order No. 951, to the
threaded hole, fit the grubscrew again and tighten it well. Ideally we recommend that you file or
grind a flat in one side of the shaft at the point where the grubscrews meet it, as this eliminates
any chance of the joint slipping.
The shaft and the throat of the tail rotor gearbox can now be fitted into the fuselage from the tail
end, at the same time engaging the front end of the shaft (B9) in the quick-release coupling. Fix
the tail rotor gearbox to the bulkhead using the three 2.9 x 13 self-tapping screws. Check the
length of the shaft (B9) one last time, i.e. the axial clearance in the coupling yoke.
Apply plenty of UHU plus endfest 300 at the point where the channeled rail (B6) is to be glued to
the bulkhead (A10), and where it rests under the cross-strut (B7) at the front end. Rotate the
channeled rail so that the channel is on top, and slide it into final position, resting against the
underside of the front cross-strut (B7).
Before the epoxy sets, rotate the tail rotor a few times by hand so that the tail rotor shaft and
guide tube align themselves in the position of least resistance.
Leave the epoxy to cure completely, then apply plenty of UHU plus endfest 300 to both parts
(A19) and press them against the fuselage sides, resting on top of the cross-strut (B7). Leave
the epoxy to set hard.
Slide the retaining collet 56.0 into place about 1-2 mm behind the union sleeve.
1.7.3 Tail rotor control linkage
The tail rotor linkage is based on a cantilever CFRP pushrod. The tail bulkhead (A9) features a
hole for this pushrod, and the rod should be able to move the tail rotor from one end-stop to the
other without fouling the bulkhead. Please note that the output arm on the tail rotor servo must
face up in this model, and not as described in the mechanics instructions.
Screw ball-links onto the two M2.5 x 75 mm threaded rods to a depth of about 7 mm. Glue the
threaded rods in both ends of the 850 mm long carbon fibre tube using UHU plus endfest 300.
There should be about 25 mm between the front end of the CFRP tube and the ball-link, whilst
at the rear end the threaded rod should be pushed into the tube to the point where the centres
of the ball sockets are 938 mm apart.

1.8 Stabiliser panels

Sand the edges of all the stabiliser panels to the cross-sections shown in the drawing. The
vertical stabiliser consists of two balsa panels, one top and one bottom, which can now be glued
together. Drill two 3 mm Ø holes in the vertical stabiliser, and temporarily screw it to the
mounting face on the tail boom using 2.9 x 13 mm self-tapping screws, taking care not to over-
tighten them; don't crush the balsa. The stabiliser is installed permanently by gluing it in place
with epoxy, but only after the model has been completed and painted.
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