GRAUPNER Skalar, Руководство пользователя

Страница: 36 / 59

elektro
Skalar
36
11. Main rotor blades
This model should be operated using GRP or CRP main rotor blades to obtain an optimal effi-
ciency. Nevertheless it is possible to use wood blades (by your own resposibility). These have to
be prepared as decribed in the next section 11.1. If you use GRP/CRP blades you can skip this
section.
11.1 Preparing wood rotor blades
If your rotor blades do not come with the bushes factory-fitted, epoxy the root bushes 4607.164
in the holes in the rotor blades.
When the epoxy has cured, rub down the blades all over using fine abrasive paper, Order No.
700.1 or 700.2.
Ideally the weight of both blades will be identical, as will the Centre of Gravity (balance point) of
both blades. You can check this by balancing the blades individually over a triangular-section
block as shown in the drawing. Mark the line of balance in both directions; the point where the
lines cross is the blade’s Centre of Gravity.
In practice it is unlikely that both blades will be identical in this way, and it can be difficult to
achieve perfection using ordinary methods. However, this is not crucially important with modern
model helicopters. What is crucial is that both blades should possess identical moments when
mounted on the rotor head. This means that it is permissible for the blades to be different
weights, provided that the difference is compensated by differing blade CGs; the method of
balancing them is described in the next section.
Apply clear dope (SPANNFIX IMMUN, Order No. 1408) to the root end of the blades, the area of
the doublers (approximately 70 mm long) and the extreme tip (around 20 mm long), and apply a
colour finish to those areas. The film is applied to the blades as shown in the drawing; first the
top surface, then the underside of the trailing edge, then the rest of the underside, overlapping at
the trailing edge. It is important that the film should be applied smoothly, without wrinkles!
11.2 Balancing the rotor blades
Screw the main rotor blades together as shown, and hang them up on a piece of thread. Apply
adhesive tape to the end of the lighter blade until the joined blades hang level.
Balance the blades carefully in this way to ensure that your main rotor does not vibrate when
spinning!