aeroplanes-第13节
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THE RANGE OF ITS USE。The subject might be
illustrated by assuming that we have a line running
from A to Z； which indicates the range of
speeds in aeroplanes。 The limits of speeds are
fairly stated as being within thirty and eighty…
five miles per hour。 Less than thirty miles are
impossible with any type of plane； and while some
have made higher speeds than eighty…five miles it
may be safe to assume that such flights took place
under conditions where the wind contributed to
the movement。
_Fig。 32。 Chart showing Range of Uses_
COMMERCIAL UTILITY。Before machines can be
used successfully they must be able to attain
slower speeds。 Alighting is the danger factor。
Speed machines are dangerous； not in flight or
at high speeds； but when attempting to land。 A
large plane surface is incompatible with speed；
which is another illustration that at high velocities
supporting surfaces are not necessary。
Commercial uses require safety as the first element；
and reliability as the next essential。 For
passenger service there must be an assurance that
it will not overturn； or that in landing danger is
not ever…present。 For the carrying of freight interrupted
service will militate against it。
How few are the attempts to solve the problem
of decreased speed； and what an eager； restless
campaign is being waged to go faster and faster；
and the addition of every mile above the record
is hailed as another illustration of the perfection
（？） of the flying machine。
To be able to navigate a machine at ten； or fifteen
miles an hour； would scarcely be interesting
enough to merit a paragraph； but such an accomplishment
would be of far more value than all of
Pequod's feats； and be more far…reaching in its
effects than a flight of two hundred miles per hour。
CHAPTER VIII
KITES AND GLIDERS
KITES are of very ancient origin； and in China；
Japan； and the Malayan Peninsula； they have been
used for many years as toys； and for the purposes
of exhibiting forms of men； animals； and particularly
dragons； in their periodical displays。
THE DRAGON KITE。The most noted of all are
the dragon kites； many of them over a hundred
feet in length； are adapted to sail along majestically；
their sinuous or snake…like motions lending
an idea of reality to their gorgeously…colored appearance
in flight。
ITS CONSTRUCTION。It is very curiously
wrought； and as it must be extremely light； bamboo
and rattan are almost wholly used； together
with rice paper； in its construction。
Fig。 33 shows one form of the arrangement； in
which the bamboo rib； A； in which only two sections
are shown； as B； B； form the backbone； and
these sections are secured together with pivot
pins C。 Each section has attached thereto a
hoop； or circularly…formed rib； D； the rib passing
through the section B； and these ribs are
connected together loosely by cords E； which run
from one to the other； as shown。
These circular ribs； D； are designed to carry a
plurality of light paper disks； F； which are attached
at intervals； and they are placed at such
angles that they serve as small wing surfaces or
aeroplanes to hold the structure in flight。
_Fig。 33。 Ribs of Dragon Kite_
THE MALAY KITE。The Malay kite； of which
Fig。 34 shows the structure； is merely made up of
two cross sticks； A； B； the vertical strip； A； being
bent and rigid； whereas the cross stick； B； is light
and yielding； so that when in flight it will bend；
as shown； and as a result it has wonderful stability
due to the dihedral angles of the two surfaces。 This kite
requires no tail to give it stability。
_Fig。 34。 The Malay Kite。_
DIHEDRAL ANGLES。This is a term to designate
a form of disposing of the wings which has been
found of great service in the single plane machines。
A plane which is disposed at a rising
angle； as A； A； Fig。 35； above the horizontal line；
is called dihedral； or diedral。
_Fig。 35。 Dihedral Angle。_
This arrangement in monoplanes does away
with the necessity of warping the planes； or
changing them while in flight。 If； however； the angle
is too great； the wind from either quarter is liable
to raise the side that is exposed。
THE COMMON KITE。While the Malay kite has
only two points of cord attachment； both along
the vertical rib； the common kite； as shown in
Fig。 36； has a four…point connection； to which the
flying cord is attached。 Since this form has no
dihedral angle； it is necessary to supply a tail；
which thus serves to keep it in equilibrium； while
in flight。
_Fig。 36。 Common Kite。_
Various modifications have grown out of the
Malay kite。 One of these forms； designed by
Eddy； is exactly like the Malay structure； but instead
of having a light flexible cross piece； it is
bent to resemble a bow； so that it is rigidly held
in a bent position； instead of permitting the wind
to give it the dihedral angle。
THE BOW KITE。Among the different types are
the bow kite； Fig。 37； and the sexagonal structure；
Fig。 38； the latter form affording an especially
large surface。
_Fig。 37。 Bow Kite。…
_Fig。 38。 Hexagonal Kite。_
THE BOX KITE。The most marked improvement
in the form of kites was made by Hargreaves；
in 1885； and called the box kite。 It has wonderful
stability； and its use； with certain modifications；
in Weather Bureau experiments； have proven its
value。
It is made in the form of two boxes； A； B； open
at the ends； which are secured together by means
of longitudinal bars； C； that extends from one to
the other； so that they are held apart a distance；
approximately； equal to the length of one of the
boxes。
_Fig。 39。 Hargreave Kite。_
Their fore and aft stability is so perfect that
the flying cord D is attached at one point only；
and the sides of the boxes provide lateral stability
to a marked degree。
THE VOISON BIPLANE。This kind of kite furnished
the suggestion for the Voison biplane；
which was one of the earlier productions in flying
machines。
Fig。 40 shows a perspective of the Voison plane；
which has vertical planes A； A； at the ends； and
also intermediate curtains B； B。 This was found
to be remarkably stable； but during its turning
movements； or in high winds； was not satisfactory；
and for that reason was finally abandoned。
LATERAL STABILITY IN KITES NOT CONCLUSIVE AS
TO PLANES。This is instanced to show that while
such a form is admirably adapted for kite purposes；
where vertical curtains are always in line
with the wind movement； and the structure is held
taut by a cord； the lateral effect； when used on a
machine which does not at all times move in line
with the moving air current。 A condition is thus
set up which destroys the usefulness of the box
kite formation。
_Fig。 40。 Voison Biplane。_
THE SPEAR KITE。This is a novel kite； with
remarkable steadiness and is usually made with
the wings on the rear end larger than those on
the forward end （Fig。 41）； as thereby the cord
A can be attached to the spear midway between
the two sets of wings。
_Fig。 41。 Spear Kite。_
THE CELLULAR KITE。Following out the suggestion
of the Hargreaves kite； numerous forms
embodying the principle of the box structure were
made and put on the market before the aeroplane
became a reality。
_Fig。 42。 Cellular Kite。_
A structure of this form is illustrated in Fig。
42。 Each box； as A； B； has therein a plurality of
vertical and horizontal partitions； so that a number
of cells are provided； the two cell…like boxes
being held apart by a bar C； axially arranged。
This type is remarkably stable； due to the small
cells； and kites of this kind are largely used for
making scientific experiments。
THE TETRAHEDRAL KITE。Prof。 Bell； inventor
of the telephone； gave a great deal of study to
kites； which resulted in the tetrahedral formation；
as shown in Fig。 43。
_Fig。 43。 Tetrahedral Kite。_
The structure； apparently； is somewhat complicated；
but an examination of a single pair of
blades； as shown at A； shows that it is built up of
triangularly…formed pieces； and that the openings
between the pieces are equal to the latter； thereby
providing a form of kite which possesses equilibrium
to a great degree。
It has never been tried with power； and it is
doubtful whether it would be successful as a sustaining
surface for flying machines； for the same
reasons that caused failure with the box…like formation
of the Voison Machine。
THE DELTOID。The deltoid is the simplest； and
the most easily constructed of all the kites。 It is
usually made from stiff cardboard； A…shaped in
outline； as shown in Figs。 44 and 45； and bent along
a central line； as at A； forming two wings； each
of which is a right…angled triangle。
_Fig。 44。 and 45。 Deltoid Formation。_
The peculiarity of t
