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the turn begins。
_Fig。 31。 Flying upside down。_
TURNING MOVEMENT。Now note the characteristic
angles of the tail； which is the controlling
factor。 In position 1 the tail is practically
horizontal。 In fact； in all machines； at
high flight； the tail is elevated so as to give little
positive angle of incidence to the supporting
planes。
In position No。 2； the tail is turned to an angle
of incidence to make the downward plunge； and
when the machine has assumed the vertical； as in
position 3； the tail is again reversed to assume
the angle； as in 1； when flying horizontally。
At the lower turn； position 4； the tail is turned
similar to the angle of position 2； which throws
the rear end of the machine down； and as the
horizontal line of flight is resumed； in an inverted
position； as in position 4； the tail has the same
angle； with relation to the frame； as the supporting
planes。
During this evolution the engine is running； and
the downward plunge develops a tremendous
speed； and the great momentum thus acquired；
together with the pulling power of the propeller
while thus in flight； is sufficient to propel it along
horizontally； whatever the plane surface curve； or
formation may be。
It is the momentum which sustains it in space；
not the air pressure beneath the wings； for
reasons which we have heretofore explained。
Flights of sufficient duration have thus been made
to prove that convex； as well as concave surfaces
are efficient； nevertheless； in its proper place we
have given an exposition of the reasoning which
led to the adoption of the concaved supporting
surfaces。
WHEN CONCAVED PLANES ARE DESIRABLE。
Unquestionably； for slow speeds the concaved wing
is desirable； as will be explained； but for high
speeds； surface formation has no value。 That is
shown by Pequod's feat。
THE SPEED MANIA。This is a type of mania
which pervades every field of activity in the building
of aeroplanes。 Speed contests are of more
importance to the spectators on exhibition
grounds than stability or durability。 Builders
pander to this； hence machines are built on lines
which disregard every consideration of safety
while at normal flight。
USES OF FLYING MACHINES。The machine as
now constructed is of little use commercially。
Within certain limitations it is valuable for scouting
purposes； and attempts have been made to
use it commercially。 But the unreliable character
of its performances； due to the many elements
which are necessary to its proper working； have
operated against it。
PERFECTION IN MACHINES MUST COME BEFORE
SPEED。Contrary to every precept in the building
of a new article； the attempt is made to make
a machine with high speed； which； in the very
nature of things； operates against its improvement。
The opposite lack of speedis of far
greater utility at this stage of its development。
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 a