Main Rotor Blades - GRAUPNER heim Starlet 50 Mode D'emploi

Starlet 50

12. Main rotor blades

Epoxy the rotor blade bushes 4607.164 in the root holes in the rotor blades, unless your blades
are supplied with these parts factory-fitted.
Allow the epoxy to set hard, then sand the blades smooth overall using fine abrasive paper,
Order No. 700.1 or 700.2.
Ideally both the weight and the Centre of Gravity of both blades should be identical. You can
check this by balancing each blade over a triangular strip of wood, as shown in the drawing.
Mark the lines of balance as shown; the blade's CG is located where the lines cross.
However, in practice it is unlikely that you will be able to achieve perfect balance and weight
distribution without a considerable amount of work, and in any case it is not that important with
modern model helicopters. The crucial factor is that the moments of both rotor blades should be
the same when they are mounted on the rotor head. This means that blades of different weights
can certainly be used, provided that the CG of the blades is also different, and compensates for
the weight discrepancy. The method of balancing the blades is described in the next section.
Apply SPANNFIX IMMUN (colour dope), Order No. 1408, over the joints, in the region of the
root doublers (approx. 70 mm from the root) and at the tip (approx. 20 mm from the tip). The film
covering should be applied in the sequence shown in the drawing: first the top surface, then the
trailing edge, then the underside. Take care with the covering; there should be no wrinkles or
bubbles!
12.1 Balancing the rotor blades
Screw the two rotor blades together as shown in the drawing, and hang this assembly from a
length of thread. Apply adhesive tape to the tip of the lighter blade until the blades hang level.
Properly balanced blades reduce vibration to a minimum, so take your time over balancing.
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