Weigh every part of your model as you construct it, and do not be content
until all symmetrically arranged parts which should weigh the same not only
look alike but do actually balance one another. (Note.--The writer always
works out the various parts of his models in grammes, not ounces.) If a
sufficiently strong propeller bearing weighing only half a gramme can be
employed, so much the better, as you have more margin left for some other
part of the model in which it would be inadvisable to cut down the weight
to a very fine limit.
Details.--To pass now to details, we have four distinct parts to deal
with:--
1. The framework, or fuselage.
2. The supporting surfaces, consisting of the main plane, or aerofoil,
behind, and the elevator in front.
3. The propellers.
4. The motor, in this case two long skeins of rubber; long, because we wish
to be able to give our motor many turns, from 700 to, say, 1,000 as a
limit, so that the duration of flight may be considerable.
[Illustration: FIG. 129.-Sections of backbone for model aeroplane.]
The Backbone.--For the backbone or central rod take a piece of pitch pine
or satin walnut 52 inches long, 5/8 inch deep, and 1/2 inch broad, and
plane it down carefully until it has a T-shaped section, as shown in Fig.
Pages:
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244