Making and experimenting with aeroplanes calls for much patience and
often ends in disappointment--the lot of inventors generally. This is
no reason why work should stop, as all progress is made by attempting
the supposedly impossible, but it will be restful after a while to turn
to the ancient and gentle art of kite making.
Incidentally, something may be learned about the effect of wind on
plane surfaces that will prove helpful in aeroplane work.
The aeroplane kite shown in Fig. 50 is simple and effective. It may be
given the appearance of a Blériot monoplane by modifying some of its
features, as shown at _b_, the planes having a slight upward slant. The
arrangement of the frames is clearly shown in the drawing. Spruce or
white pine may be used, as lightness is an essential.
The method of fastening the sticks is important. It is not wise to
halve them, as their strength will be reduced below the safety point,
and nails are likely to split them. Bind them securely with strong
linen kite cord or fine soft wire.
Kite _a_ is open to criticism on account of the single stick connecting
front and back. The second form is better, and the two long sticks may
be correspondingly lighter without reducing the ultimate strength of
the frame. The method of joining three sticks, as at the forward end,
is shown in detail in Fig. 50. Wherever a butt joint occurs, join the
two pieces by means of small strips of tin cut to size with a pair of
tinsmith snips. Drill holes through tin and sticks, pass fine soft wire
through the hole, and twist tightly with a pair of pliers.
The planes or sails may be of light, strong paper, or some light
fabric, such as lawn or cheap silk. The fabric should be cut to size,
allowing two inches each way for the hem. Pieces of cord are fastened
to the hem, and tied to the ends of the sticks through small holes
drilled for the purpose, or tied to notches cut with the knife.
The advantage of this method is that the sails, or planes, may be
drawn tightly or removed without loss of time. In this way a number
of fabrics can be used for experimental purposes. Paper, on the other
hand, must be lapped over sticks and wires, and glued.
Propellers may be fastened to front, rear, or both, to create the
appearance of a real aeroplane.
The restraining action of the cord holding one of these kites up
against the wind brings into action the same force that supports the
glider or aeroplane, and the sails, especially fabrics, assume the
curve of a boat sail, when close-hauled and sailing into the wind.
The forms that are possible are infinite, and limited only by the
imagination of the designer.
It is well to begin with one of the standard types, and leave
experimental forms until some experience has been gained.
The Americanized Malay, Eddy, or parakite is shown in Fig. 50. The two
sticks are of equal length, bound together with twine or soft wire.
Distance _c e_ should be from 14 to 18 per cent. of the total length _c
d_. The vertical stick remains straight, but cross stick _a b_ is bent
back like a bow, the distance _e f_ being 10 per cent. of the total
length of either stick, and maintained by a string from _a_ to _b_. The
four points _a c b d_ are joined by a cord drawn taut, to make sure
that the sticks are at right angles.
[Illustration: Fig. 50.]
The material should be cut as shown, the amount lapped being uniform
all around. This is important, as a slight difference in weight
between the two sides would result in erratic flying. For Eddy kites
up to three feet in height a light-weight wrapping paper will answer
very well. Larger sizes require nainsook, lawn, or China silk. Like all
the kites described here, this is a tailless one, and the method of
fastening the bridle is shown. Make a small hole in the covering, pass
a cord through, and tie it to cross the stick at its centre. Fasten the
other end about half an inch from lower end of upright, and make a loop
at _o_ for attaching the line.
The kite line should be the light and strong linen twine made
especially for this purpose, and sold by toy and sporting goods
dealers. A ball containing 600 yards of cord, strong enough to hold any
three-foot kite, will cost about fifty cents.
For larger sizes, it pays to make a reel, to save time drawing in and
to avoid bad tangles. A simple form of reel is shown in Fig. 51.
The frame has a generous-sized hole bored as shown at _h_. Cut a small
branch in the form shown, _i_, and use this as a stake. Drive it into
the ground through _h_, and use it as a pivot to shift the reel as the
wind changes. With this arrangement the kite cannot drag the reel, and
it is possible to leave the apparatus with the kite in the air. The
writer was driven to using this device after seeing his reel go tearing
across the fields until stopped by a four-foot fence. The pull exerted
at the reel by a train of three or four kites is sometimes sufficient
to give a boy all he can do to hold it. The height to which a kite will
go is illustrated by the diagram. _S_ is the starting point, and _s t_
the direction of the string at the start, when but little cord has been
played out. The position of the kite at various times is indicated by
letters _a b c d e_, the actual path being shown by dotted line. The
solid, curved lines from _s_ to these points show the position of the
cord as it is played out. This is a mathematical curve resulting from
the weight of cord and kite, wind pressure on cord, and lifting power
of the plane.
It will be seen that the kite finally moves along horizontally, no
matter how much cord is played out. This occurs when the lifting power
equals the force of gravity and wind pressure. In other words, the kite
can do no more without an increase of wind.
To make it go higher, we must raise point _s_ by tandem flying,
attaching another kite and cord to the first one, as shown at _x_.
Three or four Eddy kites may be flown in this way, the lines of equal
or unequal length joined at a common point to the main line; and,
strange as it may seem, if they are well balanced kites they will not
interfere with each other. In fact, there seems to be an electrical
repulsion among the lines, so that they spread out like a broom.
This is one of the most interesting discoveries in kite flying, though
badly upset in actual practice, when one member of the team becomes
erratic and proceeds to make a braid of the four cords by diving under
and over the others to bring about a general demoralization. For this
reason, it is wise to test each kite separately, first, to discover any
possible tendency to freakishness.
A weird experience may be enjoyed by leaving the tandem out after dark.
Run the main line down by slipping it under your arm, and walk out
until you reach the junction of the four lines, where a light-weight
lantern can be attached. Let go, and see the lantern apparently drawn
up into the air by noiseless, invisible hands.
Flags and other devices may be attached as indicated in the drawing; a
light stick at _a b_ will keep the flag from blowing up into a heap,
and loops at _a_ and _c_ are tied in the main line to avoid sliding.