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from encouraging。
Three Kinds of Aeroplanes。
There are three forms of aeroplanes； with all of which
more or less success has been attained。 These are：
The monoplane； a one…surfaced plane； like that used
by Bleriot。
The biplane； a two…surfaced plane； now used by the
Wrights； Curtiss； Farman； and others。
The triplane； a three…surfaced plane This form is
but little used； its only prominent advocate at present
being Elle Lavimer； a Danish experimenter； who has not
thus far accomplished much。
Whatever of real success has been accomplished in
aviation may be credited to the monoplane and biplane；
with the balance in favor of the latter。 The monoplane
is the more simple in construction and； where weight…
sustaining capacity is not a prime requisite； may
probably be found the most convenient。 This opinion is
based on the fact that the smaller the surface of the
plane the less will be the resistance offered to the air；
and the greater will be the speed at which the machine
may be moved。 On the other hand； the biplane has a
much greater plane surface （double that of a monoplane
of the same size） and consequently much greater weight…
carrying capacity。
Differences in Biplanes。
While all biplanes are of the same general construction
so far as the main planes are concerned； each aviator
has his own ideas as to the 〃rigging。〃
Wright； for instance； places a double horizontal rudder
in front； with a vertical rudder in the rear。 There
are no partitions between the main planes； and the
bicycle wheels used on other forms are replaced by skids。
Voisin； on the contrary； divides the main planes with
vertical partitions to increase stability in turning； uses
a single…plane horizontal rudder in front； and a big box…
tail with vertical rudder at the rear； also the bicycle
wheels。
Curtiss attaches horizontal stabilizing surfaces to the
upper plane； has a double horizontal rudder in front；
with a vertical rudder and horizontal stabilizing surfaces
in rear。 Also the bicycle wheel alighting gear。
CHAPTER V。
CONSTRUCTING A GLIDING MACHINE。
First decide upon the kind of a machine you want
monoplane； biplane； or triplane。 For a novice the biplane
will； as a rule； be found the most satisfactory as
it is more compact and therefore the more easily handled。
This will be easily understood when we realize that the
surface of a flying machine should be laid out in proportion
to the amount of weight it will have to sustain。
The generally accepted rule is that 152 square feet of
surface will sustain the weight of an average…sized man；
say 170 pounds。 Now it follows that if these 152 square
feet of surface are used in one plane； as in the monoplane；
the length and width of this plane must be greater
than if the same amount of surface is secured by using
two planesthe biplane。 This results in the biplane
being more compact and therefore more readily manipulated
than the monoplane； which is an important item
for a novice。
Glider the Basis of Success。
Flying machines without motors are called gliders。 In
making a flying machine you first construct the glider。
If you use it in this form it remains a glider。 If you
install a motor it becomes a flying machine。 You must
have a good glider as the basis of a successful flying
machine。
It will be well for the novice； the man who has never
had any experience as an aviator； to begin with a glider
and master its construction and operation before he
essays the more pretentious task of handling a fully…
equipped flying machine。 In fact； it is essential that he
should do so。
Plans for Handy Glider。
A glider with a spread （advancing edge） of 20 feet； and
a breadth or depth of 4 feet； will be about right to begin
with。 Two planes of this size will give the 152 square
yards of surface necessary to sustain a man's weight。
Remember that in referring to flying machine measurements
〃spread〃 takes the place of what would ordinarily
be called 〃length；〃 and invariably applies to the long
or advancing edge of the machine which cuts into the air。
Thus； a glider is spoken of as being 20 feet spread； and
4 feet in depth。 So far as mastering the control of the
machine is concerned； learning to balance one's self in
the air； guiding the machine in any desired direction by
changing the position of the body； etc。； all this may be
learned just as readily； and perhaps more so； with a 20…
foot glider than with a larger apparatus。
Kind of Material Required。
There are three all…important features in flying machine
construction； viz。： lightness； strength and extreme
rigidity。 Spruce is the wood generally used for glider
frames。 Oak； ash and hickory are all stronger； but they
are also considerably heavier； and where the saving of
weight is essential； the difference is largely in favor of
spruce。 This will be seen in the following table：
Weight Tensile Compressive
per cubic ft。 Strength Strength
Wood in lbs。 lbs。 per sq。 in。 lbs。 per sq in。
Hickory 53 12；000 8；500
Oak 50 12；000 9；000
Ash 38 12；000 6；000
Walnut 38 8；000 6；000
Spruce 25 8；000 5；000
Pine 25 5；000 4；500
Considering the marked saving in weight spruce has
a greater percentage of tensile strength than any of the
other woods。 It is also easier to find in long； straight…
grained pieces free from knots； and it is this kind only
that should be used in flying machine construction。
You will next need some spools or hanks of No。 6
linen shoe thread； metal sockets； a supply of strong
piano wire； a quantity of closely…woven silk or cotton
cloth； glue； turnbuckles； varnish； etc。
Names of the Various Parts。
The long strips； four in number； which form the front
and rear edges of the upper and lower frames； are called
the horizontal beams。 These are each 20 feet in length。
These horizontal beams are connected by upright strips；
4 feet long； called stanchions。 There are usually 12 of
these； six on the front edge； and six on the rear。 They
serve to hold the upper plane away from the lower one。
Next comes the ribs。 These are 4 feet in length （projecting
for a foot over the rear beam）； and while intended
principally as a support to the cloth covering of
the planes； also tend to hold the frame together in a
horizontal position just as the stanchions do in the vertical。
There are forty…one of these ribs； twenty…one on
the upper and twenty on the lower plane。 Then come
the struts； the main pieces which join the horizontal
beams。 All of these parts are shown in the illustrations；
reference to which will make the meaning of the
various names clear。
Qu