flying machines-第10章

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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　out　of　the　way。　Cover　the

tongue　thoroughly　with　glue；　and　also　put　some　on　the

inside　of　the　groove。　Use　plenty　of　glue。　Now　press

the　tongue　into　the　groove；　and　keep　the　ends　firmly

together　until　the　glue　is　thoroughly　dried。　Rub　off　the

joint　lightly　with　sand…paper　to　remove　any　of　the　glue

which　may　have　oozed　out；　and　slip　the　sleeve　into　place

over　the　joint。　Tack　the　sleeve　in　position　with　small

copper　tacks；　and　you　will　have　an　ideal　splice。



The　same　operation　is　to　be　repeated　on　each　of　the

four　frame　pieces。　Two　20…foot　pieces　joined　in　this

way　will　give　a　substantial　frame；　but　when　suitable

timber　of　this　kind　can　not　be　had；　three　pieces；　each　6

feet　11　inches　long；　may　be　used。　This　would　give　20

feet　9　inches；　of　which　8　inches　will　be　taken　up　in　the

two　joints；　leaving　the　frame　20　feet　1　inch　long。



Installation　of　Motor。



Next　comes　the　installation　of　the　motor。　The　kinds

and　efficiency　of　the　various　types　are　described　in　the

following　chapter　（IX）。　All　we　are　interested　in　at

this　point　is　the　manner　of　installation。　This　varies

according　to　the　personal　ideas　of　the　aviator。　Thus　one

man　puts　his　motor　in　the　front　of　his　machine；　another

places　it　in　the　center；　and　still　another　finds　the　rear　of

the　frame　the　best。　All　get　good　results；　the　comparative

advantages　of　which　it　is　difficult　to　estimate。　Where

one　man；　as　already　explained；　flies　faster　than　another；

the　one　beaten　from　the　speed　standpoint　has　an　advantage

in　the　matter　of　carrying　weight；　etc。



The　ideas　of　various　well…known　aviators　as　to　the

correct　placing　of　motors　may　be　had　from　the　following：



WrightsIn　rear　of　machine　and　to　one　side。



CurtissWell　to　rear；　about　midway　between　upper

and　lower　planes。



RaichIn　rear；　above　the　center。



Brauner…SmithIn　exact　center　of　machine。



Van　AndenIn　center。



Herring…BurgessDirectly　behind　operator。



VoisinIn　rear；　and　on　lower　plane。



BleriotIn　front。



R。　E。　P。In　front。



The　One　Chief　Object。



An　even　distribution　of　the　load　so　as　to　assist　in

maintaining　the　equilibrium　of　the　machine；　should　be

the　one　chief　object　in　deciding　upon　the　location　of　the

motor。　It　matters　little　what　particular　spot　is　selected

so　long　as　the　weight　does　not　tend　to　overbalance　the

machine；　or　to　〃throw　it　off　an　even　keel。〃　It　is　just

like　loading　a　vessel；　an　operation　in　which　the　expert

seeks　to　so　distribute　the　weight　of　the　cargo　as　to　keep

the　vessel　in　a　perfectly　upright　position；　and　prevent　a

〃list〃　or　leaning　to　one　side。　The　more　evenly　the　cargo

is　distributed　the　more　perfect　will　be　the　equilibrium　of

the　vessel　and　the　better　it　can　be　handled。　Sometimes；

when　not　properly　stowed；　the　cargo　shifts；　and　this　at

once　affects　the　position　of　the　craft。　When　a　ship

〃lists〃　to　starboard　or　port　a　preponderating　weight　of

the　cargo　has　shifted　sideways；