A well-stocked tool chest will be of great assistance to the builder of
model aeroplanes, but it is by no means essential. A few simple tools,
easily obtained, will be found to answer. First of these comes a
serviceable pair of nippers. You will need them to bend the axles of
your propellers, in adjusting the motors, and for a score of uses. A
pair of nippers with a cutting edge is best. Always be sure to slip
these in your pocket before flying your model, for you are sure to need
them.
A fine gimlet, or a needle drill, will be found useful in a score of
ways. They cost but a few cents. A handle which may be adjusted to
drills of different size is best. A drill one thirty-second of an inch
in diameter will be found especially useful. The parts of your model are
likely to be delicate and easily split, even while driving a small brad.
You can avoid the danger of splitting by first using the needle drill,
even for small brads, and then enlarging the hole, if necessary, with a
larger drill or a gimlet.
[Illustration: Percy Pierce launching a model]
[Illustration: A French model built of aluminium]
A fine saw will be found very useful,—the finer the better. The timber
used for the frame is so light and soft that it is likely to split. A
gig saw will be found just the thing for cutting out propeller blanks
and other parts, but it is not essential. If your model be made of
metal, a small soldering iron will, of course, be found
indispensable,—the smaller the better. The metal parts are very
delicate, and the iron should have as fine a point as possible. Such an
iron can be obtained at a hardware store for a few cents. If you do not
know how to solder neatly consult some tinsmith.
[Illustration: Diagram for making the planes]
In addition to good cutting tools, a good half-inch chisel is most
important. A concave chisel will be found handy in carving propellers.
Some of the best propellers have been whittled out with an ordinary
penknife, and sometimes a dull one at that, so that after all a good
penknife is the most essential tool of all. With this little handful of
tools, you will find you can build up the most delicate models.
The world has been ransacked for material which will give the greatest
possible strength for its weight. The use of aluminum is, of course,
familiar. The search has also brought out the comparatively unknown
metal, "magnalium," which, although a trifle heavier, is believed to be
much more desirable on account of its greater strength. In a search for
strong, light wood the builders of aeroplanes have searched the tropics.
One of their discoveries has been balsic wood, which is of a feather
weight. It is exceedingly soft and easily worked, but has the drawback
of being rather pithy and easily split. A severe jar is likely to
discover some weak point. It will be found valuable, however, for the
shorter members of the model. Some model builders use balsic wood as a
filling for hollow sticks. The wood may be strengthened by covering with
cloth glued firmly about it. It is also used as a filling for thin
aluminum tubing.
In all the search for materials nothing has been found to compare with
bamboo for lightness and strength. A number of successful model
aeroplanes have been built this year in which the central sticks and
frames are built entirely of bamboo. Bamboo is especially valuable in
constructing the smaller members. It can be bent either by the dry-heat
process, described elsewhere, or by steaming. Bear in mind that the
strongest part of the stick lies just beneath the hard glazed outer
surface. The only drawback of bamboo is a tendency to split at the ends.
The extreme lightness of the material on the other hand makes it
possible to make rigid joints by glueing and winding with fine thread
touched with glue.
[Illustration: Working drawing of the Flemming Williams model]
[Illustration: An imported Flemming Williams model. English record 2600
feet.]
The lighter woods, whitewood and poplar, are much used by model
builders. They are easy to work, especially whitewood, because of its
freedom from knots and cross grains. Some builders prefer ash on account
of its strength. Beech has rather less strength, some fifteen per cent,
while spruce is little more than half as strong as ash. The quality of
the wood varies considerably according to its nearness to the bark of
the tree. The wood used for model aeroplanes should be well seasoned; a
year is not too long.
Motor bases are of two general divisions. The "single stickers," or
bases consisting of one member, are commonly called "spars," while the
more complicated frameworks are designated as "built-up" frames. The
spar type is, of course, the simplest to construct, and, as many
believe, the most efficient of all forms. The simpler the design, as a
rule, the less chance will there be of breakage. For the beginner the
use of plain, honest sticks is, of course, to be recommended.
The built-up motor bases, on the other hand, make a more attractive
model to the eye. There is besides an opportunity to reduce the weight
of the frame while retaining the same strength. An examination of the
models illustrated elsewhere will show to what an art such construction
has been brought. By ingenious bracing it is possible to construct motor
bases of strips one-sixteenth of an inch, or even less, in width, and
yet render the whole sufficiently rigid to withstand the pull of
powerful twin motors.
Your frame may be considerably lightened by using hollow sticks or
shafts in place of solid members. A stick three-fourths of an inch wide
formed of light lath one-eighth of an inch thick will weigh no more than
a solid piece one quarter of an inch square. Such a member is stronger
than the small, solid stick; it bends less readily under the pull of
your motors, and renders the entire frame far more rigid. It will also
be found much more satisfactory to mount the planes upon such a frame.
A little practice will enable you to make a very satisfactory stick of
this pattern. Secure a light strip one-eighth of an inch thick and of a
width one-eighth of an inch less than that of the stick you intend to
build. A one-inch stick is probably larger than you will need. The
following directions are intended for a stick three-fourths of an inch
square.
First cut three square plugs one-half an inch square and one-fourth of
an inch thick, and placing one at either end and one in the middle to
form a core, build your frame about them. The edges should overlap and
be glued continuously together, and the plugs fastened in position with
brads driven from the middle of the four sides. When dry, cut away the
glue, sandpaper and varnish.
Some model builders prefer a T-section-shaped spar, which is almost as
light as the hollow stick, besides being easier to construct. We assume
that you are working with eight-inch strips, which will prove heavy
enough for ordinary purposes. Prepare one strip one-half an inch wide,
the desired length of your base, and the second strip three-eighths of
an inch wide, the thickness and length being the same.
Now fasten the smaller strip at the center of the long strip, glueing it
first in position. When dry, drive a series of fine brads along the
center of the back of the larger strip. Cut away the glue and sandpaper.
The T-shaped stick will be found strong enough for all ordinary demands.
The rubber strands of your motor may be carried either above or below
it.
The H-shaped-section stick is rather more difficult to build, but it
will be found somewhat stronger, weight for weight. If you are using
one-eighth strips, cut two lengths one-half an inch wide, and a third
length three-eighths of an inch wide. Fasten the smaller pieces to the
middle of one of these strips, as in the case of the T stick, with glue
and brads. When dry, attach the remaining strip opposite, glueing and
nailing as before. Some builders prepare these strips by cutting out the
grooves with a chisel, thus making a one-piece strip. This requires very
careful workmanship, however, and is scarcely worth the trouble.
The motor frame may be still further lightened by using a trussed frame.
The weight of this member may be cut in two in this way without
sacrificing its strength. To build such a part secure two strips of wood
one-eighth of an inch thick, one inch in width, and cut to the desired
length. Now from the same material cut six blocks, one-half an inch in
length, and set these at regular intervals along one side of the strip.
They may be glued or nailed in position, or both. A small brad will hold
them in place. In working with such delicate material it will be well to
first drill the holes with a fine drill. Next fasten the second strip
above them, nailing and glueing as before.
[Illustration: Storing energy for a long distance flight]