aeroplanes-第16章
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greater。
As an example of this； let us take a speed of ten
miles an hour； which means a pressure of one…
half pound。 Double this speed； and we have 20
miles。 Multiplying one…half pound by 4； the result
is 2 pounds。 Again； double 20； which means
40 miles； and multiplying 2 by 4； the result is 8。
Doubling forty is eighty miles an hour； and again
multiplying 8 by 4； we have 32 as the pounds pressure
at a speed of 80 miles an hour。
The anemometer； however； is constant in its
speed。 If the pointer should turn once a second
at 10 miles an hour； it would turn twice at 20 miles
an hour； and four times a second at 40 miles an
hour。
GYROSCOPIC BALANCE。Some advance has been
made in the use of the gyroscope for the purpose
of giving lateral stability to an aeroplane。 While
the best of such devices is at best a makeshift；
it is well to understand the principle on which they
operate； and to get an understanding how they are
applied。
THE PRINCIPLE INVOLVED。The only thing
known about the gyroscope is； that it objects to
changing the plane of its rotation。 This statement
must be taken with some allowance； however；
as； when left free to move； it will change in
one direction。
To explain this without being too technical； examine
Fig。 63； which shows a gyroscopic top； one
end of the rim A； which supports the rotating
wheel B； having a projecting finger C； that is
mounted on a pin…point on the upper end of the
pedestal D。
_Fig。 63。 The Gyroscope。_
When the wheel B is set in rotation it will maintain
itself so that its axis E is horizontal； or at
any other angle that the top is placed in when the
wheel is spun。 If it is set so the axis is horizontal
the wheel B will rotate on a vertical plane；
and it forcibly objects to any attempt to make it
turn except in the direction indicated by the
curved arrows F。
The wheel B will cause the axis E to swing
around on a horizontal plane； and this turning
movement is always in a certain direction in relation
to the turn of the wheel B； and it is obvious；
therefore； that to make a gyroscope that
will not move； or swing around an axis； the placing
of two such wheels side by side； and rotated
in opposite directions； will maintain them in a
fixed position； this can also be accomplished by
so mounting the two that one rotates on a plane
at right angles to the other。
_Fig。 64。 Application of the Gyroscope。_
THE APPLICATION OF THE GYROSCOPE。Without
in any manner showing the structural details of
the device； in its application to a flying machine；
except in so far as it may be necessary to explain
its operation； we refer to Fig。 64； which
assumes that A represents the frame of the aeroplane；
and B a frame for holding the gyroscopic
wheel C； the latter being mounted so it rotates on
a horizontal plane； and the frame B being hinged
fore and aft； so that it is free to swing to the right
or to the left。
For convenience in explaining the action； the
planes E are placed at right angles to their regular
positions； F being the forward margin of the
plane； and G the rear edge。 Wires H connect
the ends of the frame B with the respective
planes； or ailerons； E； and another wire I joins
the downwardly…projecting arms of the two
ailerons； so that motion is transmitted to both at
the same time； and by a positive motion in either
direction。
_Fig。 65。 Action of the Gyroscope。_
In the second figure； 65； the frame of the aeroplane
is shown tilted at an angle； so that its right
side is elevated。 As the gyroscopic wheel remains
level it causes the aileron on the right side to
change to a negative angle； while at the same
time giving a positive angle to the aileron on the
left side； which would； as a result； depress the
right side； and bring the frame of the machine
back to a horizontal position。
FORE AND AFT GYROSCOPIC CONTROL。It is
obvious that the same application of this force may
be applied to control the ship fore and aft； although
it is doubtful whether such a plan would
have any advantages； since this should be wholly
within the control of the pilot。
Laterally the ship should not be out of balance；
fore and aft this is a necessity； and as the great
trouble with all aeroplanes is to control them
laterally； it may well be doubted whether it would
add anything of value to the machine by having
an automatic fore and aft control； which might；
in emergencies； counteract the personal control of
the operator。
ANGLE INDICATOR。In flight it is an exceedingly
difficult matter for the pilot to give an accurate
idea of the angle of the planes。 If the air is
calm and he is moving over a certain course； and
knows； from experience； what his speed is； he may
be able to judge of this factor； but he cannot tell
what changes take place under certain conditions
during the flight。
For this purpose a simple little indicator may
be provided； shown in Fig。 66； which is merely a
vertical board A； with a pendulum B； swinging
fore and aft from a pin a which projects out
from the board a short distance above its center。
The upper end of the pendulum has a heart…
shaped wire structure D； that carries a sliding
weight E。 Normally； when the aeroplane is on
an even keel； or is even at an angle； the weight
E rests within the bottom of the loop D； but
should there be a sudden downward lurch or a
quick upward inclination； which would cause the
pendulum below to rapidly swing in either
direction； the sliding weight E would at once move
forward in the same direction that the pendulum
had moved； and thus counteract； for the instant
only； the swing； when it would again drop back
into its central position。
_Fig。 66。 Angle Indicator。_
With such an arrangement； the pendulum would
hang vertically at all times； and the pointer below；
being in range of a circle with degrees
indicated thereon； and the base attached to the
frame of the machine； can always be observed；
and the conditions noted at the time the changes
take place。
PENDULUM STABILIZER。In many respects the
use of a pendulum has advantages over the gyroscope。
The latter requires power to keep it in
motion。 The pendulum is always in condition
for service。 While it may be more difficult to
adjust the pendulum； so that it does not affect
the planes by too rapid a swing； or an oscillation
which is beyond the true angle desired； still； these
are matters which； in time； will make the pendulum
a strong factor in lateral stability。
_Fig。 67。 Simple Pendulum Stabilizer。_
It is an exceedingly simple matter to attach the
lead wires from an aileron to the pendulum。 In
Fig。 67 one plan is illustrated。 The pendulum
A swings from the frame B of the machine； the
ailerons a being in this case also shown at right
angles to their true positions。
The other； Fig。 68； assumes that the machine is
exactly horizontal； and as the pendulum is in a
vertical position； the forward edges of both ailerons
are elevated； but when the pendulum swings
both ailerons will be swung with their forward
margins up or down in unison； and thus the proper
angles are made to right the machine。
STEERING AND CONTROLLING WHEEL。For the
purpose of concentrating the control in a single
wheel； which has not alone a turning motion； but
is also mounted in such a manner that it will oscillate
to and fro； is very desirable； and is adapted
for any kind of machine。
_Fig。 68。 Pendulum Stabilizers。_
Fig。 69 shows such a structure； in which A
represents the frame of the machine； and B a
segment for the stem of the wheel； the segment
being made of two parts； so as to form a guideway
for the stem a to travel between； and the segment
is placed so that the stem will travel in a
fore and aft direction。
The lower end of the stem is mounted in a
socket； at D； so that while it may be turned； it
will also permit this oscillating motion。 Near its
lower end is a cross bar E from which the wires
run to the vertical control plane； and also to the
ailerons； if the machine is equipped with them； or
to the warping ends of the planes。
_Fig。 69。 Steering and Control Wheel。_
Above the cross arms is a loose collar F to
which the fore and aft cords are attached that go
to the elevators； or horizontal planes。 The upper
end of the stem has a wheel G； which may also be
equipped with the throttle and spark levers。
AUTOMATIC STABILIZING WINGS。Unquestionably；
the best stabilizer is one which will act on
its own initiative。 The difficulty with automatic
devices is； that they act too late； as a general
thing； to be effective。 The device represented in
Fig。 70 is very simple； and in practice is found to
be most efficient。
In this Fig。 70 A and B represent the upper
and the lower planes； respectively。 Near the end
vertical standards a； D； are narrow wings E E；
F F； hinged on a fore and aft line close below
each of the planes； the wings being at such distances
from the standards C D that when they
swing outwardly they will touch the standards；
and when in that position will be at an angle of
about 35 degrees from the planes A B。
_Fig。 70。 Automatic Stabilizing Wings。_
_Fig。 71。 Action of Stabilizing Wings。_
Inwardly they are permitted to swing up and
lie parallel with the planes； as shown in Fig。 71
where the planes are at an angle。 In turning； all
machines skid；that is they travel obliquely
across the field； and this is also true when the
ship is sailing at right angles to the course of the
wind。
This will be made clear by reference to Fig。
72； in which the dart A represents the direction
of the movement of the aeroplane； and B the
direction of the wind； the vertical rudder a being
almost at right angles to the course of the wind。
_Fig。 72。 Into the Wind at an Angle。_
In turning a circle the same thing takes place
as shown in Fig。 73； with the tail at a different
angle； so as to give a turning movement to the
plane。 It will be seen that in the circling movement
the tendency of the aeroplane is to fly out
at a tangent； shown by the line D； so that the
planes of the machine are not radially…disposed
with reference to the center of the circle； the line
E showing the true radial line。
Referring now to Fig。 71； it will be seen that
this skidding motion of the machine swings the
wings E F inwardly； so that they offer no resistance
to the oblique movement； but the wings E
E； at the other end of the planes are swung outwardly；
to provide an angle； which tends to raise
up the inner end of the planes； and thereby seek
to keep the planes horizontal。
_Fig。 73。 Turning a Circle。_
BAROMETERS。These instruments are used for
registering heights。 A barometer is a device for
measuring the wei
