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第13章

aeroplanes-第13章

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feet of surface; which would make each 5' by 30'

in size; or; it may be decided to make the planes

narrower; and proportionally longer。 This is immaterial。

The shorter the planes transversely;

the greater will be the stability; and the wider the

planes the less will be the lift; comparatively。



RULE FOR PLACING THE PLANES。The rule for

placing the planes is to place them apart a distance

equal to the width of the planes themselves;

so that if we decide on making them five feet wide;

they should be placed at least five feet apart。

This rule; while it is an admirable one for slow

movements or when starting flight; is not of any

advantage while in rapid flight。



If the machine is made with front and rear

horizontally…disposed rudders; or elevators; they

also serve as sustaining surfaces; which; for the

present will be disregarded。



Lay off a square A; Fig。 49a; in which the vertical

lines B; B; and the horizontal lines C; C; are

5' long; and draw a cross D within this; the lines

running diagonally from the corners。



Now step off from the center cross line D; three

spaces; each five feet long; to a point E; and join

this point by means of upper and lower bars F;

G; with the upper and lower planes; so as to form

the tail frame。



_Fig。 49a。 Rule for spacing Planes。_



As shown in Fig。 50; the planes should now be

indicated; and placed at an angle of about 8 degrees

angle; which are illustrated; H being the

upper and I the lower plane。 Midway between the

forward edges of the two planes; is a horizontal

line J; extending forwardly; and by stepping off

the width of two planes; a point K is made; which

forms the apex of a frame L; the rear ends of the

bars being attached to the respective planes H; I;

at their forward edges。



_Fig。 50。 Frame of Control Planes。_



_Fig。 51。 and Fig。 52。_



ELEVATING PLANES。We must now have the general

side elevation of the frame; the planes; their

angles; the tail and the rudder support; and the

frame for the forward elevator。



To this may be added the forward elevating

plane L; the rear elevator; or tail M; and the vertical

steering rudder N。



The frame which supports the structure thus

described; may be made in a variety of ways; the

object being to provide a resilient connection for

the rear wheel O。



Fig。 52 shows a frame which is simple in construction

and easily attached。 The lower fore

and aft side bars P have the single front wheel

axle at the forward end; and the aft double wheels

at the rear end; a flexible bar Q; running from the

rear wheel axle to the forward end of the lower

plane。



A compression spring R is also mounted between

the bar and rear end of the lower plane to

take the shock of landing。 The forward end of

the bar P has a brace S extending up to the front

edge of the lower plane; and another brace T connects

the bars P; S; with the end of the forwardly…

projecting frame。



_Fig。 53。 Plan view。_



The full page view; Fig。 53; represents a plan

view; with one of the wings cut away; showing the

general arrangement of the frame; and the three

wheels required for support; together with the

brace bars referred to。



The necessity of the rear end elevation will

now be referred to。 The tail need not; necessarily;

be located at a point on a horizontal line

between the planes。 It may be higher; or lower

than the planes; but it should not be in a position

to touch the ground when the machine is about

to ascend。



_Fig。 54。 Alighting。_



The angle of ascension in the planes need not

exceed 25 degrees so the frame does not require

an angle of more than 17 degrees。 This is shown

in Fig。 54; where the machine is in a position

ready to take the air at that angle; leaving ample

room for the steering rudder。



ACTION IN ALIGHTING。Also; in alighting; the

machine is banked; practically in the same

position thus shown; so that it alights on the rear

wheels O。



The motor U is usually mounted so its shaft is

midway between the planes; the propeller V being

connected directly with the shaft; and being behind

the planes; is on a medial line with the

machine。



The control planes L; M; N; are all connected up

by means of flexible wires with the aviator at the

set W; the attachments being of such a character

that their arrangement will readily suggest themselves

to the novice。



THE MONOPLANE。From a spectacular standpoint

a monoplane is the ideal flying machine。 It

is graceful in outline; and from the fact that it

closely approaches the form of the natural flyer;

seems to be best adapted as a type; compared with

the biplane。



THE COMMON FLY。So many birds have been

cited in support of the various flying theories that

the house fly; as an example has been disregarded。

We are prone to overlook the small insect; but it

is; nevertheless; a sample which is just as potent

to show the efficiency of wing surface as the condor

or the vulture。



The fly has greater mobility than any other flying

creature。 By the combined action of its legs

and wings it can spring eighteen inches in the

tenth of a second; and when in flight can change

its course instantaneously。



If a sparrow had the same dexterity; proportionally;

it could make a flight of 800 feet in the

same time。 The posterior legs of the fly are the

same length as its body; which enable it to spring

from its perch with amazing facility。



_Fig。 55。 Common Fly。 Outstretched Wings。_



The wing surface; proportioned to its body and

weight; is no less a matter for wonder and consideration。



In Fig。 55 is shown the outlines of the fly with

outstretched wings。 Fig。 56 represents it with

the wing folded; and Fig。 57 is a view of a wing

with the relative size of the top of the body shown

in dotted lines。



_Fig。 56。 Common Fly。 Folded Wings。_



The first thing that must attract attention; after

a careful study is the relative size of the body

and wing surface。 Each wing is slightly smaller

than the upper surface of the body; and the thickness

of the body is equal to each wing spread。



_Fig。 57。 Relative size of wing and body。_



The weight; compared with sustaining surface;

if expressed in understandable terms; would be

equal to sixty pounds for every square foot of surface。



STREAM LINES。The next observation is; that

what are called stream lines do not exist in the fly。

Its head is as large in cross section as its body;

with the slightest suggestion only; of a pointed

end。 Its wings are perfectly flat; forming a true

plane; not dished; or provided with a cambre; even;

that upward curve; or bulge on the top of the aeroplane

surface; which seems to possess such a fascination

for many bird flight advocates。



It will also be observed that the wing connection

with the body is forward of the line A; which

represents the point at which the body will balance

itself; and this line passes through the wings

so that there is an equal amount of supporting

surface fore and aft of the line。



Again; the wing attachment is at the upper side

of the body; and the vertical dimension of the

body; or its thickness; is equal to four…fifths of the

length of he wing。



The wing socket permits a motion similar to a

universal joint; Fig。 55 showing how the inner

end of the wing has a downward bend where it

joins the back; as at B。



THE MONOPLANE FORM。For the purpose of

making comparisons the illustrations of the monoplane

show a machine of 300 square feet of surface;

which necessitates a wing spread of forty

feet from tip to tip; so that the general dimensions

of each should be 18 1/2 feet by 8 1/2 feet at its

widest point。



First draw a square forty feet each way; as in

Fig。 58; and through this make a horizontal line

1; and four intermediate vertical lines are then

drawn; as 2; 3; 4; 5; thus providing five divisions;

each eight feet wide。 In the first division the

planes A; B; are placed; and the tail; or elevator

C; is one…half the width of the last division。



_Fig。 58。 Plan of Monoplane。_



The frame is 3 1/2 feet wide at its forward end;

and tapers down to a point at its rear end; where

the vertical control plane D is hinged; and the

cross struts E; E; are placed at the division lines

3; 4; 5。



The angles of the planes; with relation to the

frame; are usually greater than in the biplane;

for the reason that the long tail plane requires

a greater angle to be given to the planes when

arising; or; instead of this; the planes A; B; are

mounted high enough to permit of sufficient angle

for initiating flight without injuring the tail D。



Some monoplanes are built so they have a support

on wheels placed fore and aft。 In others

the tail is supported by curved skids; as shown

at A; Fig。 59; in which case the forward

supporting wheels are located directly beneath the planes。

As the planes are at about eighteen degrees

angle; relative to the frame; and the tail plane

B is at a slight negative angle of incidence; as

shown at the time when the engine is started; the

air rushing back from the propeller; elevates the

tail; and as the machine moves forwardly over

the ground; the tail raises still higher; so as to

give a less angle of incidence to the planes while

skimming along the surface of the ground。



_Fig。 59。 Side Elevation; Monoplane。_



In order to mount; the tail is suddenly turned

to assume a sharp negative angle; thus swinging

the tail downwardly; and this increases the angle

of planes to such an extent that the machine leaves

the ground; after which the tail is brought to the

proper angle to assure horizontal flight。



The drawing shows a skid at the forward end;

attached to the frame which carries the wheels。

The wheels are mounted beneath springs so that

when the machine alights the springs yield sufficiently

to permit the skids to strike the ground;

and they; therefore; act as brakes; to prevent the

machine from traveling too far。







CHAPTER X



POWER AND ITS APPLICATION





THIS is a phase of the flying machine which has

the greatest interest to the boy。 He instinctively

sees the direction in which the machine has its

life;its moving principle。 Planes have their

fascination; and propellers their mysterious elements;

but power is the great and absorbing question

with him。



We shall try to make its application plain in

the following pages。 We have nothing to do here

with the construction and operation of the motor

itself; as; to do that justice; would require pages。



FEATURES IN POWER APPLICATION。It will be

more directly to the point to consider the following

features of the power and its application:



1。 The amount of power necessary。



2。 How to calculate the power applied。



3。 I

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