flying machines-第3章

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afforded　by　the　rear　cell；　which　operated　upon　air

already　set　in　motion　downward　by　the　front　cell；　so

nothing　more　was　done　with　it；　for　it　never　occurred　to

the　writer　to　try　it　as　a　kite　and　he　thus　missed　the

distinction　which　attaches　to　Hargrave's　name。



Sir　Hiram　Maxim　also　introduced　fore　and　aft　superposed

surfaces　in　his　wondrous　flying　machine　of　1893；

but　he　relied　chiefly　for　the　lift　upon　his　main　large　surface

and　this　necessitated　so　many　guys；　to　prevent　distortion；

as　greatly　to　increase　the　head　resistance　and

this；　together　with　the　unstable　equilibrium；　made　it

evident　that　the　design　of　the　machine　would　have　to

be　changed。



How　Lilienthal　Was　Killed。



In　1895；　Otto　Lilienthal；　the　father　of　modern　aviation；

the　man　to　whose　method　of　experimenting　almost　all

present　successes　are　due；　after　making　something　like

two　thousand　glides　with　monoplanes；　added　a　superposed

surface　to　his　apparatus　and　found　the　control　of

it　much　improved。　The　two　surfaces　were　kept　apart

by　two　struts　or　vertical　posts　with　a　few　guy　wires；　but

the　connecting　joints　were　weak　and　there　was　nothing

like　trussing。　This　eventually　cost　his　most　useful　life。

Two　weeks　before　that　distressing　loss　to　science；　Herr

Wilhelm　Kress；　the　distinguished　and　veteran　aviator

of　Vienna；　witnessed　a　number　of　glides　by　Lilienthal

with　his　double…decked　apparatus。　He　noticed　that　it

was　much　wracked　and　wobbly　and　wrote　to　me　after

the　accident：　〃The　connection　of　the　wings　and　the

steering　arrangement　were　very　bad　and　unreliable。　I

warned　Herr　Lilienthal　very　seriously。　He　promised

me　that　he　would　soon　put　it　in　order；　but　I　fear　that　he

did　not　attend　to　it　immediately。〃



In　point　of　fact；　Lilienthal　had　built　a　new　machine；

upon　a　different　principle；　from　which　he　expected　great

results；　and　intended　to　make　but　very　few　more　flights

with　the　old　apparatus。　He　unwisely　made　one　too

many　and；　like　Pilcher；　was　the　victim　of　a　distorted

apparatus。　Probably　one　of　the　joints　of　the　struts

gave　way；　the　upper　surface　blew　back　and　Lilienthal；

who　was　well　forward　on　the　lower　surface；　was　pitched

headlong　to　destruction。



Experiments　by　the　Writer。



In　1896；　assisted　by　Mr。　Herring　and　Mr。　Avery；　I

experimented　with　several　full　sized　gliding　machines；

carrying　a　man。　The　first　was　a　Lilienthal　monoplane

which　was　deemed　so　cranky　that　it　was　discarded　after

making　about　one　hundred　glides；　six　weeks　before

Lilienthal's　accident。　The　second　was　known　as　the

multiple　winged　machine　and　finally　developed　into　five

pairs　of　pivoted　wings；　trussed　together　at　the　front　and

one　pair　in　the　rear。　It　glided　at　angles　of　descent　of

10　or　11　degrees　or　of　one　in　five；　and　this　was　deemed

too　steep。　Then　Mr。　Herring　and　myself　made　computations

to　analyze　the　resistances。　We　attributed　much

of　them　to　the　five　front　spars　of　the　wings　and　on　a

sheet　of　cross…barred　paper　I　at　once　drew　the　design　for

a　new　three…decked　machine　to　be　built　by　Mr。　Herring。



Being　a　builder　of　bridges；　I　trussed　these　surfaces

together；　in　order　to　obtain　strength　and　stiffness。　When

tested　in　gliding　flight　the　lower　surface　was　found　too

near　the　ground。　It　was　taken　off　and　the　remaining

apparatus　now　consisted　of　two　surfaces　connected　together

by　a　girder　composed　of　vertical　posts　and　diagonal

ties；　specifically　known　as　a　〃Pratt　truss。〃　Then

Mr。　Herring　and　Mr。　Avery　together　devised　and　put

on　an　elastic　attachment　to　the　tail。　This　machine

proved　a　success；　it　being　safe　and　manageable。　Over

700　glides　were　made　with　it　at　angles　of　descent　of　8

to　10　degrees；　or　one　in　six　to　one　in　seven。



First　Proposed　by　Wenham。



The　elastic　tail　attachment　and　the　trussing　of　the

connecting　frame　of　the　superposed　wings　were　the　only

novelties　in　this　machine；　for　the　superposing　of　the

surfaces　had　first　been　proposed　by　Wenham；　but　in

accordance　with　the　popular　perception；　which　bestows

all　the　credit　upon　the　man　who　adds　the　last　touch

making　for　success　to　the　labors　of　his　predecessors；　the

machine　has　since　been　known　by　many　persons　as　the

〃Chanute　type〃　of　gliders；　much　to　my　personal　gratification。



It　has　since　been　improved　in　many　ways。　Wright

Brothers；　disregarding　the　fashion　which　prevails　among

birds；　have　placed　the　tail　in　front　of　their　apparatus　and

called　it　a　front　rudder；　besides　placing　the　operator　in

horizontal　position　instead　of　upright；　as　I　did；　and　also

providing　a　method　of　warping　the　wings　to　preserve

equilibrium。　Farman　and　Delagrange；　under　the　very

able　guidance　and　constructive　work　of　Voisin　brothers；

then　substituted　many　details；　including　a　box　tail　for

the　dart…like　tail　which　I　used。　This　may　have　increased

the　resistance；　but　it　adds　to　the　steadiness。　Now　the

tendency　in　France　seems　to　be　to　go　back　to　the　monoplane。



Monoplane　Idea　Wrong。



The　advocates　of　the　single　supporting　surface　are

probably　mistaken。　It　is　true　that　a　single　surface

shows　a　greater　lift　per　square　foot　than　superposed

surfaces　for　a　given　speed；　but　the　increased　weight　due

to　leverage　more　than　counterbalances　this　advantage　by

requiring　heavy　spars　and　some　guys。　I　believe　that


the　future　aeroplane　dynamic　flier　will　consist　of　superposed

surfaces；　and；　now　that　it　has　been　found　that　by

imbedding　suitably　shaped　spars　in　the　cloth　the　head

resistance　may　be　much　diminished；　I　see　few　objections

to　superposing　three；　four　or　even　five　surfaces　properly

trussed；　and　thus　obtaining　a　compact；　handy；　manageable

and　comparatively　light　apparatus。＇2＇





＇2＇　Aeronautics。







CHAPTER　II。



THEORY；　DEVELOPMENT；　AND　USE。





While　every　craft　that　navigates　the　air　is　an　airship；

all　airships　are　not　flying　machines。　The　balloon；

for　instance；　is　an　airship；　but　it　is　not　what　is　known

among　aviators　as　a　flying　machine。　This　latter　term

is　properly　used　only　in　referring　to　heavier…than…air

machines　which　have　no　gas…bag　lifting　devices；　and　are　made　to

really　fly　by　the　application　of　engine　propulsion。



Mechanical　Birds。



All　successful　flying　machinesand　there　are　a　number

of　themare　based　on　bird　action。　The　various

designers　have　studied　bird　flight　and　soaring；　mastered

its　technique　as　devised　by　Nature；　and　the　modern　flying

machine　is　the　result。　On　an　exaggerated；　enlarged

scale　the　machines　which　are　now　navigating　the　air

are　nothing　more　nor　less　than　mechanical　birds。



Origin　of　the　Aeroplane。



Octave　Chanute；　of　Chicago；　may　well　be　called　〃the

developer　of　the　flying　machine。〃　Leaving　balloons　and

various　forms　of　gas…bags　out　of　consideration；　other

experimenters；　notably　Langley　and　Lilienthal；　antedated

him　in　attempting　the　navigation　of　the　air　on

aeroplanes；　or　flying　machines；　but　none　of　them　were

wholly　successful；　and　it　remained　for　Chanute　to　demonstrate

the　practicability　of　what　was　then　called　the

gliding　machine。　This　term　was　adopted　because　the

apparatus　was；　as　the　name　implies；　simply　a　gliding

machine；　being　without　motor　propulsion；　and　intended

solely　to　solve　the　problem　of　the　best　form　of

construction。　The　biplane；　used　by　Chanute　in　1896；　is

still　the　basis　of　most　successful　flying　machines；　the

only　radical　difference　being　that　motors；　rudders；　etc。；

have　been　added。



Character　of　Chanute's　Experiments。



It　was　the　privilege　of　the　author　of　this　book　to　be

Mr。　Chanute's　guest　at　Millers；　Indiana；　in　1896；　when；

in　collaboration　with　Messrs。　Herring　and　Avery；　he　was

conducting　the　series　of　experiments　which　have　since

made　possible　the　construction　of　the　modern　flying

machine　which　such　successful　aviators　as　the　Wright

brothers　and　others　are　now　using。　It　was　a　wild

country；　much　frequented　by　eagles；　hawks；　and　similar

birds。　The　enthusiastic　trio；　Chanute；　Herring　and

Avery；　would　watch　fo