flying machines-第7章

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by　wire　cables　at　the　will　of　the　operator。



Allowing　that　the　amateur　has　become　reasonably　expert

in　the　manipulation　of　the　glider　he　should；　before

constructing　an　actual　flying　machine；　equip　his　glider

with　a　rudder。



Cross　Pieces　for　Rudder　Beam。



To　do　this　he　should　begin　by　putting　in　a　cross　piece；

2　feet　long　by　1/4x3/4　inches　between　the　center　struts；

in　the　lower　plane。　This　may　be　fastened　to　the　struts

with　bolts　or　braces。　The　former　method　is　preferable。

On　this　cross　piece；　and　on　the　rear　frame　of　the　plane

itself；　the　rudder　beam　is　clamped　and　bolted。　This

rudder　beam　is　8　feet　11　inches　long。　Having　put　these

in　place　duplicate　them　in　exactly　the　same　manner　and

dimensions　from　the　upper　frame　The　cross　pieces　on

which　the　ends　of　the　rudder　beams　are　clamped　should

be　placed　about　one　foot　in　advance　of　the　rear　frame

beam。



The　Rudder　Itself。



The　next　step　is　to　construct　the　rudder　itself。　This

consists　of　two　sections；　one　horizontal；　the　other　vertical。

The　latter　keeps　the　aeroplane　headed　into　the　wind；

while　the　former　keeps　it　steadypreserves　the　equilibrium。



The　rudder　beams　form　the　top　and　bottom　frames　of

the　vertical　rudder。　To　these　are　bolted　and　clamped

two　upright　pieces；　3　feet；　10　inches　in　length；　and　3/4

inch　in　cross　section。　These　latter　pieces　are　placed　about

two　feet　apart。　This　completes　the　framework　of　the

vertical　rudder。　See　next　page　（59）。



For　the　horizontal　rudder　you　will　require　two　strips

6　feet　long；　and　four　2　feet　long。　Find　the　exact　center

of　the　upright　pieces　on　the　vertical　rudder；　and　at　this

spot　fasten　with　bolts　the　long　pieces　of　the　horizontal；

placing　them　on　the　outside　of　the　vertical　strips。　Next

join　the　ends　of　the　horizontal　strips　with　the　2…foot

pieces；　using　small　screws　and　corner　braces。　This　done

you　will　have　two　of　the　2…foot　pieces　left。　These　go　in

the　center　of　the　horizontal　frame；　〃straddling〃　the

vertical　strips；　as　shown　in　the　illustration。



The　framework　is　to　be　covered　with　cloth　in　the

same　manner　as　the　planes。　For　this　about　ten　yards

will　be　needed。



Strengthening　the　Rudder。



To　ensure　rigidity　the　rudder　must　be　stayed　with

guy　wires。　For　this　purpose　the　No。　12　piano　wire　is

the　best。　Begin　by　running　two　of　these　wires　from　the

top　eye…bolts　of　stanchions　3　and　4；　page　37；　to　rudder

beam　where　it　joins　the　rudder　planes；　fastening　them

at　the　bottom。　Then　run　two　wires　from　the　top　of　the

rudder　beam　at　the　same　point；　to　the　bottom　eye…bolts

of　the　same　stanchions。　This　will　give　you　four　diagonal

wires　reaching　from　the　rudder　beam　to　the　top

and　bottom　planes　of　the　glider。　Now；　from　the　outer

ends　of　the　rudder　frame　run　four　similar　diagonal　wires

to　the　end　of　the　rudder　beam　where　it　rests　on　the

cross　piece。　You　will　then　have　eight　truss　wires

strengthening　the　connection　of　the　rudder　to　the　main

body　of　the　glider。



The　framework　of　the　rudder　planes　is　then　to　be

braced　in　the　same　way；　which　will　take　eight　more

wires；　four　for　each　rudder　plane。　All　the　wires　are

to　be　connected　at　one　end　with　turn…buckles　so　the

tension　may　be　regulated　as　desired。



In　forming　the　rudder　frame　it　will　be　well　to　mortise

the　corners；　tack　them　together　with　small　nails；　and

then　put　in　a　corner　brace　in　the　inside　of　each　joint。

In　doing　this　bear　in　mind　that　the　material　to　be　thus

fastened　is　light；　and　consequently　the　lightest　of　nails；

screws；　bolts　and　corner　pieces；　etc。；　is　necessary。







CHAPTER　VIII。



THE　REAL　FLYING　MACHINE。



We　will　now　assume　that　you　have　become　proficient

enough　to　warrant　an　attempt　at　the　construction　of　a

real　flying　machineone　that　will　not　only　remain　suspended

in　the　air　at　the　will　of　the　operator；　but　make

respectable　progress　in　whatever　direction　he　may　desire　to　go。

The　glider；　it　must　be　remembered；　is　not

steerable；　except　to　a　limited　extent；　and　moves　only　in

one　directionagainst　the　wind。　Besides　this　its　power

of　flotationsuspension　in　the　airis　circumscribed。



Larger　Surface　Area　Required。



The　real　flying　machine　is　the　glider　enlarged；　and

equipped　with　motor　and　propeller。　The　first　thing　to

do　is　to　decide　upon　the　size　required。　While　a　glider

of　20　foot　spread　is　large　enough　to　sustain　a　man　it

could　not　under　any　possible　conditions；　be　made　to　rise

with　the　weight　of　the　motor；　propeller　and　similar

equipment　added。　As　the　load　is　increased　so　must　the

surface　area　of　the　planes　be　increased。　Just　what　this

increase　in　surface　area　should　be　is　problematical　as

experienced　aviators　disagree；　but　as　a　general　proposition

it　may　be　placed　at　from　three　to　four　times　the　area　of

a　20…foot　glider。＇3＇



＇3＇　See　Chapter　XXV。



Some　Practical　Examples。



The　Wrights　used　a　biplane　41　feet　in　spread；　and　6　1/2

ft。　deep。　This；　for　the　two　planes；　gives　a　total　surface

area　of　538　square　feet；　inclusive　of　auxiliary　planes。

This　sustains　the　engine　equipment；　operator；　etc。；　a　total

weight　officially　announced　at　1；070　pounds。　It　shows

a　lifting　capacity　of　about　two　pounds　to　the　square

foot　of　plane　surface；　as　against　a　lifting　capacity　of

about　1/2　pound　per　square　foot　of　plane　surface　for　the

20…foot　glider。　This　same　Wright　machine　is　also　reported

to　have　made　a　successful　flight；　carrying　a　total

load　of　1；100　pounds；　which　would　be　over　two　pounds

for　each　square　foot　of　surface　area；　which；　with　auxiliary

planes；　is　538　square　feet。



To　attain　the　same　results　in　a　monoplane；　the　single

surface　would　have　to　be　60　feet　in　spread　and　9　feet

deep。　But；　while　this　is　the　mathematical　rule；　Bleriot

has　demonstrated　that　it　does　not　always　hold　good。

On　his　record…breaking　trip　across　the　English　channel；

July　25th；　1909；　the　Frenchman　was　carried　in　a

monoplane　24　1/2　feet　in　spread；　and　with　a　total　sustaining

surface　of　150　1/2　square　feet。　The　total　weight　of

the　outfit；　including　machine；　operator　and　fuel　sufficient

for　a　three…hour　run；　was　only　660　pounds。　With

an　engine　of　（nominally）　25　horsepower　the　distance　of

21　miles　was　covered　in　37　minutes。



Which　is　the　Best？



Right　here　an　established　mathematical　quantity　is

involved。　A　small　plane　surface　offers　less　resistance

to　the　air　than　a　large　one　and　consequently　can　attain

a　higher　rate　of　speed。　As　explained　further　on　in　this

chapter　speed　is　an　important　factor　in　the　matter　of

weight…sustaining　capacity。　A　machine　that　travels　one…

third　faster　than　another　can　get　along　with　one…half　the

surface　area　of　the　latter　without　affecting　the　load。　See

the　closing　paragraph　of　this　chapter　on　this　point。　In

theory　the　construction　is　also　the　simplest；　but　this　is

not　always　found　to　be　so　in　practice。　The　designing

and　carrying　into　execution　of　plans　for　an　extensive

area　like　that　of　a　monoplane　involves　great　skill　and

cleverness　in　getting　a　framework　that　will　be　strong

enough　to　furnish　the　requisite　support　without　an　undue　excess

of　weight。　This　proposition　is　greatly　simplified

in　the　biplane　and；　while　the　speed　attained　by　the　latter

may　not　be　quite　so　great　as　that　of　the　monoplane；　it

has　much　larger　weight…carrying　capacity。



Proper　Sizes　For　Frame。



Allowing　that　the　biplane　form　is　selected　the　construction

may　be　practically　identical　with　that　of　the

20…foot　glider　described　in　Chapter　V。；　except　as　to　size

and　elimination　of　the　armpieces。　In　size　the　surface

planes　should　be　about　twice　as　large　as　those　of　the

20…foot　glider；　viz：　40　feet　spread　instead　of　20；　and　6　feet

deep　instead　of　3。　The　horizontal　beams；　struts；　stanchions；

ribs；　etc。；　should　also　be　increased　in　size　proportionately。



While　care　in　the　selection　of　clear；　straight…grained

timber　is　important　in　the　glider；　it　is　still　more　important

in　the　construction　of　a　motor…equipped　flying

machine　as　the　strain　on　the　various　parts　will　be　much

greater。



How　to　Splice　Timbers。



It　is　practically　certain　that　you　will　have　to　resort　to

splicing　the　horizontal　beams　as　it　will　be　difficult；　if　not

impossible；　to　find　40…foot　pieces　of　timber　totally　free

from　knots　and　worm　holes；　and　of　straight　grain。



If　splicing　is　necessary　select　two　good　20…foot　pieces；

3　inches　wide　and　1　1/2　inches　thick；　and　one　10…foot　long；

of　the　same　thickness　and　width。　Plane　off　the　bottom

sides　of　the　10…foot　strip；　beginning　about　two　feet　back

from　each　end；　and　taper　them　so　the　strip　will　be　about

3/4　inch　thick　at　the　extreme　ends。　Lay　the　two　20…foot

beams　end　to　end；　and　under　the　joint　thus　made　place

the　10…foot　strip；　with　the　planed…off　ends　downward。

The　joint　of　the　20…foot　pieces　should　be　directly　in　the

center　of　the　10…foot　piece。　Bore　ten　holes　（with　a　1/4…

inch　augur）　equi…distant　apart　through　the　20…foot

strips　and　the　10…foot　strip　under　them。　Through　these

holes　run　1/4…inch　stove　bolts　with　round；　beveled　heads。

In　placing　these　bolts　use　washers　top　and　bottom；　one

between　the　head　and　the　top　beam；　and　the　other　between

the　bottom　beam　and　the　screw　nut　which　holds

the　bolt。　Screw　the　nuts　down　hard　so　as　to　bring　the

two　beams　tightly　together；　and　you　will　have　a　rigid

40…foot　beam。



Splicing　with　Metal　Sleeves。



An　even　better　way　of　making　a　splice　is　by　tonguing

and　grooving　the　ends　of　the　frame　pieces　and　enclosing

them　in　a　metal　sleeve；　but　it　requires　more　mechanical

skill　than　the　method　first　named。　The　operation　of

tonguing　and　grooving　is　especially　delicate　and　calls

for　extreme　nicety　of　touch　in　the　handling　of　tools；　but

if　this　dexterity　is　possessed　the　job　will　be　much　more

satisfactory　than　one　done　with　a　third　timber。



As　the　frame　pieces　are　generally　about　1　1/2　inch　in

diameter；　the　tongue　and　the　groove　into　which　the

tongue　fits　must　be　correspondingly　small。　Begin　by

sawing　into　one　side　of　one　of　the　frame　pieces　about　4

inches　back　from　the　end。　Make　the　cut　about　1/2　inch

deep。　Then　turn　the　piece　over　and　duplicate　the　cut。

Next　saw　down　from　the　end　to　these　cuts。　When　the

sawed…out　parts　are　removed　you　will　have　a　〃tongue〃

in　the　end　of　the　frame　timber　4　inches　long　and　1/2　inch

thick。　The　next　move　is　to　saw　out　a　5/8…inch　groove　in

the　end　of　the　frame　piece　which　is　to　be　joined。　You

will　have　to　use　a　small　chisel　to　remove　the　5/8…inch　bit。

This　will　leave　a　groove　into　which　the　tongue　will　fit

easily。



Joining　the　Two　Pieces。



Take　a　thin　metal　sleevethis　is　merely　a　hollow　tube

of　aluminum　or　brass　open　at　each　end8　inches　long；

and　slip　it　over　either　the　tongued　or　grooved　end　of　one

of　the　frame　timbers。　It　is　well　to　have　the　sleeve　fit

snugly；　and　this　may　necessitate　a　sand…papering　of　the

frame　pieces　so　the　sleeve　will　slip　on。



Push　the　sleeve　well　back