in¡¡space¡£
Such¡¡a¡¡condition¡¡would¡¡be¡¡the¡¡same£»¡¡so¡¡far¡¡as
the¡¡angles¡¡of¡¡the¡¡planes¡¡are¡¡concerned£»¡¡with¡¡a
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The¡¡stabilizing¡¡quality¡¡of¡¡the¡¡kite¡¡may¡¡be¡¡perfect£»
as¡¡the¡¡wind¡¡varies¡¡from¡¡side¡¡to¡¡side£»¡¡but¡¡the
aeroplane£»¡¡being¡¡free£»¡¡moves¡¡to¡¡the¡¡right¡¡or¡¡to
the¡¡left£»¡¡and¡¡does¡¡not¡¡adjust¡¡itself¡¡by¡¡means¡¡of¡¡a
fixed¡¡point£»¡¡but¡¡by¡¡a¡¡movable¡¡one¡£
SIMILARITY¡¡OF¡¡FORE¡¡AND¡¡AFT¡¡CONTROL¡£Fore
and¡¡aft£»¡¡however£»¡¡the¡¡kite¡¡and¡¡aeroplane¡¡act¡¡the
same¡£¡¡Fig¡£¡¡48¡¡shows¡¡a¡¡diagram¡¡which¡¡illustrates
the¡¡forces¡¡which¡¡act¡¡on¡¡the¡¡kite£»¡¡and¡¡by¡¡means
of¡¡which¡¡it¡¡adjusts¡¡its¡¡angle¡¡automatically¡£
Let¡¡us¡¡assume¡¡that¡¡the¡¡kite¡¡A¡¡is¡¡flown¡¡from
a¡¡cord¡¡B£»¡¡so¡¡that¡¡its¡¡angle¡¡is¡¡22¡¡1/2¡¡degrees£»¡¡the
wind¡¡being¡¡15¡¡miles¡¡per¡¡hour¡¡to¡¡maintain¡¡the
cord¡¡B¡¡at¡¡that¡¡angle¡£¡¡When¡¡the¡¡wind¡¡increases
to¡¡20¡¡miles¡¡an¡¡hour¡¡there¡¡is¡¡a¡¡correspondingly
greater¡¡lift¡¡against¡¡the¡¡kite¡£
_Fig¡£¡¡48¡£¡¡Action¡¡of¡¡Wind¡¡forces¡¡on¡¡Kite¡£_
As¡¡its¡¡angle¡¡is¡¡fixed¡¡by¡¡means¡¡of¡¡the¡¡loop¡¡C£»
it¡¡cannot¡¡change¡¡its¡¡angle¡¡with¡¡reference¡¡to¡¡the
cord£»¡¡or¡¡independently¡¡of¡¡it£»¡¡and¡¡its¡¡only¡¡course
is¡¡to¡¡move¡¡up¡¡higher¡¡and¡¡assume¡¡the¡¡position
shown¡¡by¡¡the¡¡figure¡¡at¡¡D£»¡¡and¡¡the¡¡angle¡¡of¡¡incidence
of¡¡the¡¡kite¡¡is¡¡therefore¡¡changed¡¡to¡¡15¡¡degrees£»
or¡¡even¡¡to¡¡10¡¡degrees¡£
In¡¡the¡¡case¡¡of¡¡the¡¡aeroplane¡¡the¡¡effect¡¡is¡¡similar
from¡¡the¡¡standpoint¡¡of¡¡power¡¡and¡¡disposition
of¡¡the¡¡planes¡£¡¡If¡¡it¡¡has¡¡sufficient¡¡power£»¡¡and¡¡the
angle¡¡of¡¡the¡¡planes¡¡is¡¡not¡¡changed£»¡¡it¡¡will¡¡ascend£»
if¡¡the¡¡planes¡¡are¡¡changed¡¡to¡¡15¡¡degrees¡¡to¡¡correspond
with¡¡the¡¡kite¡¡angle¡¡it¡¡will¡¡remain¡¡stationary¡£
GLIDING¡¡FLIGHT¡£The¡¡earliest¡¡attempt¡¡to¡¡fly
by¡¡gliding¡¡is¡¡attributed¡¡to¡¡Oliver£»¡¡a¡¡Monk¡¡of
Malmesbury¡¡who£»¡¡in¡¡1065¡¡prepared¡¡artificial
wings£»¡¡and¡¡with¡¡them¡¡jumped¡¡from¡¡a¡¡tower£»¡¡being
injured¡¡in¡¡the¡¡experiment¡£
Nearly¡¡700¡¡years¡¡later£»¡¡in¡¡1801£»¡¡Resnier£»¡¡a
Frenchman£»¡¡conducted¡¡experiments¡¡with¡¡varying
results£»¡¡followed¡¡by¡¡Berblinger£»¡¡in¡¡1842£»¡¡and
LeBris£»¡¡a¡¡French¡¡sailor£»¡¡in¡¡1856¡£
In¡¡1884£»¡¡J¡£¡¡J¡£¡¡Montgomery£»¡¡of¡¡California£»¡¡designed
a¡¡successful¡¡glider£»¡¡and¡¡in¡¡1889¡¡Otto¡¡and
Gustav¡¡Lilienthal¡¡made¡¡the¡¡most¡¡extended¡¡tests£»
in¡¡Germany£»¡¡and¡¡became¡¡experts¡¡in¡¡handling
gliders¡£
Pilcher£»¡¡in¡¡England£»¡¡was¡¡the¡¡next¡¡to¡¡take¡¡up¡¡the
subject£»¡¡and¡¡in¡¡1893¡¡made¡¡many¡¡successful¡¡glides£»
all¡¡of¡¡the¡¡foregoing¡¡machines¡¡being¡¡single¡¡plane
surfaces£»¡¡similar¡¡to¡¡the¡¡monoplane¡£
Long¡¡prior¡¡to¡¡1896¡¡Octave¡¡Chanute£»¡¡an
engineer£»¡¡gave¡¡the¡¡subject¡¡much¡¡study£»¡¡and¡¡in¡¡that
year¡¡made¡¡many¡¡remarkable¡¡flights£»¡¡developing
the¡¡double¡¡plane£»¡¡now¡¡known¡¡as¡¡the¡¡biplane¡£
He¡¡was¡¡an¡¡ardent¡¡believer¡¡in¡¡the¡¡ability¡¡of¡¡man
to¡¡fly¡¡by¡¡soaring¡¡means£»¡¡and¡¡without¡¡using¡¡power
for¡¡the¡¡purpose¡£
It¡¡is¡¡doubtful¡¡whether¡¡gliders¡¡contributed¡¡much
to¡¡the¡¡art¡¡in¡¡the¡¡direction¡¡of¡¡laterally¡¡stabilizing
aeroplanes¡£¡¡They¡¡taught¡¡useful¡¡lessons¡¡with¡¡respect
to¡¡area¡¡and¡¡fore¡¡and¡¡aft¡¡control¡£
The¡¡kite¡¡gave¡¡the¡¡first¡¡impulse¡¡to¡¡seek¡¡out¡¡a
means¡¡for¡¡giving¡¡equilibrium¡¡to¡¡planes£»¡¡and
Montgomery¡¡made¡¡a¡¡kite¡¡with¡¡warping¡¡wings¡¡as
early¡¡as¡¡1884¡£
Penaud£»¡¡a¡¡Frenchman£»¡¡in¡¡1872£»¡¡made¡¡a¡¡model
aeroplane¡¡which¡¡had¡¡the¡¡stabilizing¡¡means¡¡in¡¡the
tail¡£¡¡All¡¡these¡¡grew¡¡out¡¡of¡¡kite¡¡experiments£»¡¡and
all¡¡gliders¡¡followed¡¡the¡¡kite¡¡construction£»¡¡or¡¡the
principles¡¡involved¡¡in¡¡them£»¡¡so¡¡that£»¡¡really£»¡¡there
is¡¡but¡¡one¡¡intervening¡¡step¡¡between¡¡the¡¡kite¡¡and
the¡¡flying¡¡machine£»¡¡as¡¡we¡¡know¡¡it£»¡¡the¡¡latter¡¡being
merely¡¡kites¡¡with¡¡power¡¡attached£»¡¡as¡¡substitutes
for¡¡the¡¡cords¡£
ONE¡¡OF¡¡THE¡¡USES¡¡OF¡¡GLIDER¡¡EXPERIMENTS¡£
There¡¡is¡¡one¡¡direction¡¡in¡¡which¡¡gliders¡¡are¡¡valuable
to¡¡the¡¡boy¡¡and¡¡to¡¡the¡¡novice¡¡who¡¡are¡¡interested
in¡¡aviation¡£¡¡He¡¡may¡¡spend¡¡a¡¡lifetime¡¡in
gliding¡¡and¡¡not¡¡advance¡¡in¡¡the¡¡art¡£¡¡It¡¡is
questionable¡¡whether¡¡in¡¡a¡¡scientific¡¡way¡¡it¡¡will¡¡be¡¡of
any¡¡service¡¡to¡¡him£»¡¡but¡¡experiments¡¡of¡¡this¡¡character
give¡¡confidence£»¡¡the¡¡ability¡¡to¡¡quickly¡¡grasp
a¡¡situation£»¡¡and¡¡it¡¡will¡¡thus¡¡teach¡¡self¡¡reliance¡¡in
emergencies¡£
When¡¡in¡¡a¡¡glider¡¡quick¡¡thinking¡¡is¡¡necessary¡£
The¡¡ability¡¡to¡¡shift¡¡from¡¡one¡¡position¡¡to¡¡another£»
to¡¡apply¡¡the¡¡weight¡¡where¡¡required¡¡instantaneously£»
to¡¡be¡¡able¡¡during¡¡the¡¡brief¡¡exciting¡¡moment
of¡¡flight¡¡to¡¡know¡¡just¡¡what¡¡to¡¡do£»¡¡requires¡¡alertness¡£
Some¡¡are¡¡so¡¡wedded¡¡to¡¡the¡¡earth¡¡that¡¡slight
elevation¡¡disturbs¡¡them¡£¡¡The¡¡sensation¡¡in¡¡a
glider¡¡while¡¡in¡¡flight¡¡is¡¡unlike¡¡any¡¡other¡¡experience¡£
It¡¡is¡¡like¡¡riding¡¡a¡¡lot¡¡of¡¡tense¡¡springs£»¡¡and¡¡the
exhilaration¡¡in¡¡gliding¡¡down¡¡the¡¡side¡¡of¡¡a¡¡hill£»
with¡¡the¡¡feet¡¡free¡¡and¡¡body¡¡suspended£»¡¡is¡¡quite
different¡¡from¡¡riding¡¡in¡¡an¡¡aeroplane¡¡with¡¡power
attached¡£
HINTS¡¡IN¡¡GLIDING¡£It¡¡seems¡¡to¡¡be¡¡a¡¡difficult
matter¡¡to¡¡give¡¡any¡¡advice¡¡in¡¡the¡¡art¡¡of¡¡gliding¡£¡¡It
is¡¡a¡¡feat¡¡which¡¡seems¡¡to¡¡necessitate¡¡experiment
from¡¡first¡¡to¡¡last¡£¡¡During¡¡the¡¡hundreds¡¡of¡¡tests
personally¡¡made£»¡¡and¡¡after¡¡witnessing¡¡thousands
of¡¡attempts£»¡¡there¡¡seems¡¡to¡¡be¡¡only¡¡a¡¡few¡¡suggestions
or¡¡possible¡¡directions¡¡in¡¡which¡¡caution¡¡might
be¡¡offered¡£
First£»¡¡in¡¡respect¡¡to¡¡the¡¡position¡¡of¡¡the¡¡body¡¡at
the¡¡moment¡¡of¡¡launching¡£¡¡The¡¡glider¡¡is¡¡usually
so¡¡made¡¡that¡¡in¡¡carrying¡¡it£»¡¡preparatory¡¡to¡¡making
the¡¡run¡¡and¡¡the¡¡leap¡¡required¡¡to¡¡glide£»¡¡it¡¡is¡¡held
so¡¡that¡¡it¡¡balances¡¡in¡¡the¡¡hands¡£
Now¡¡the¡¡center¡¡of¡¡air¡¡pressure¡¡in¡¡gliding¡¡may
not¡¡be¡¡at¡¡the¡¡same¡¡point¡¡as¡¡its¡¡sustaining¡¡weight
when¡¡held¡¡by¡¡the¡¡hand£»¡¡and¡¡furthermore£»¡¡as¡¡the
arm¡pits£»¡¡by¡¡which¡¡the¡¡body¡¡of¡¡the¡¡experimenter
are¡¡held¡¡while¡¡gliding£»¡¡are¡¡not¡¡at¡¡the¡¡same¡¡point£»
but¡¡to¡¡the¡¡rear¡¡of¡¡the¡¡hands£»¡¡the¡¡moment¡¡the¡¡glider
is¡¡launched¡¡too¡¡great¡¡a¡¡weight¡¡is¡¡brought¡¡to¡¡the
rear¡¡margin¡¡of¡¡the¡¡planes£»¡¡hence¡¡its¡¡forward¡¡end
lifts¡¡up¡£
This¡¡condition¡¡will¡¡soon¡¡manifest¡¡itself£»¡¡and¡¡be
corrected¡¡by¡¡the¡¡experimenter£»¡¡but¡¡there¡¡is¡¡another
difficulty¡¡which¡¡is¡¡not¡¡so¡¡easy¡¡to¡¡discover
and¡¡so¡¡quick¡¡to¡¡remedy£»¡¡and¡¡that¡¡is¡¡the¡¡swing¡¡of
the¡¡legs¡¡the¡¡moment¡¡the¡¡operator¡¡leaves¡¡the
ground¡£
The¡¡experimenter¡¡learns£»¡¡after¡¡many¡¡attempts£»
that¡¡gliding¡¡is¡¡a¡¡matter¡¡of¡¡a¡¡few¡¡feet¡¡only£»¡¡and¡¡he
anticipates¡¡landing¡¡too¡¡soon£»¡¡and¡¡the¡¡moment¡¡he
leaps¡¡from¡¡the¡¡ground¡¡the¡¡legs¡¡are¡¡swung¡¡forwardly
ready¡¡to¡¡alight¡£
This¡¡is¡¡done¡¡unconsciously£»¡¡just¡¡as¡¡a¡¡jumper
swings¡¡his¡¡legs¡¡forwardly¡¡in¡¡the¡¡act¡¡of¡¡alighting¡£
Such¡¡a¡¡motion¡¡naturally¡¡disturbs¡¡the¡¡fore¡¡and¡¡aft
stability¡¡of¡¡the¡¡gliding¡¡machine£»¡¡by¡¡tilting¡¡up¡¡the
forward¡¡margin£»¡¡and¡¡it¡¡banks¡¡against¡¡the¡¡air£»
instead¡¡of¡¡gliding¡£
The¡¡constant¡¡fear¡¡of¡¡all¡¡gliders¡¡is£»¡¡that¡¡the
machine¡¡will¡¡point¡¡downwardly£»¡¡and¡¡his¡¡motion£»
as¡¡well¡¡as¡¡the¡¡position¡¡of¡¡the¡¡body£»¡¡tend¡¡to¡¡shoot
it¡¡upwardly£»¡¡instead¡£
CHAPTER¡¡IX
AEROPLANE¡¡CONSTRUCTION
As¡¡may¡¡be¡¡inferred¡¡from¡¡the¡¡foregoing¡¡statements£»
there¡¡are¡¡no¡¡definite¡¡rules¡¡for¡¡the¡¡construction
of¡¡either¡¡type¡¡of¡¡flying¡¡machine£»¡¡as¡¡the
flying¡¡models¡¡vary¡¡to¡¡such¡¡an¡¡extent¡¡that¡¡it¡¡is
difficult¡¡to¡¡take¡¡either¡¡of¡¡them¡¡as¡¡a¡¡model¡¡to¡¡represent
the¡¡preferred¡¡type¡¡of¡¡construction¡£
LATERAL£»¡¡AND¡¡FORE¡¡AND¡¡AFT¡£The¡¡term¡¡lateral
should¡¡be¡¡understood£»¡¡as¡¡applied¡¡to¡¡aeroplanes¡£
It¡¡is¡¡always¡¡used¡¡to¡¡designate¡¡the¡¡direction¡¡at
right¡¡angles¡¡to¡¡the¡¡movement¡¡of¡¡the¡¡machine¡£
Fore¡¡and¡¡aft¡¡is¡¡a¡¡marine¡¡term¡¡meaning¡¡lengthwise£»
or¡¡from¡¡front¡¡to¡¡rear£»¡¡hence¡¡is¡¡always¡¡at¡¡right
angles¡¡to¡¡the¡¡lateral¡¡direction¡£
The¡¡term¡¡transverse¡¡is¡¡equivalent¡¡to¡¡lateral£»
in¡¡flying¡¡machine¡¡parlance£»¡¡but¡¡there¡¡is¡¡this
distinction£º¡¡Transverse¡¡has¡¡reference¡¡to¡¡a¡¡machine
or¡¡object¡¡which£»¡¡like¡¡the¡¡main¡¡planes¡¡of¡¡an¡¡aeroplane£»
are¡¡broader£»¡¡£¨that¡¡is£»from¡¡end¡¡to¡¡end£©
than¡¡their¡¡length£»¡¡£¨from¡¡front¡¡to¡¡rear£©¡£
On¡¡the¡¡other¡¡hand£»¡¡lateral¡¡has¡¡reference¡¡to¡¡side
branches£»¡¡as£»¡¡for¡¡instance£»¡¡the¡¡monoplane¡¡wings£»
which¡¡branch¡¡out¡¡from¡¡the¡¡sides¡¡of¡¡the¡¡fore¡¡and
aft¡¡body¡£
STABILITY¡¡AND¡¡STABILIZATION¡£These¡¡terms¡¡constantly
appear¡¡in¡¡describing¡¡machines¡¡and¡¡their
operations¡£¡¡If¡¡the¡¡flying¡¡structure£»¡¡whatever¡¡it
may¡¡be£»¡¡has¡¡means¡¡whereby¡¡it¡¡is¡¡kept¡¡from¡¡rocking
from¡¡side¡¡to¡¡side£»¡¡it¡¡has¡¡stability£»¡¡which¡¡is¡¡usually
designated¡¡as¡¡lateral¡¡stability¡£¡¡The¡¡mechanism
for¡¡doing¡¡this¡¡is¡¡called¡¡a¡¡stabilizer¡£
THE¡¡WRIGHT¡¡SYSTEM¡£The¡¡Wright¡¡machine¡¡has
reference¡¡solely¡¡to¡¡the¡¡matter¡¡of¡¡laterally¡¡controlling
the¡¡flying¡¡structure£»¡¡and¡¡does¡¡not¡¡pertain
to¡¡the¡¡form¡¡or¡¡shape¡¡of¡¡the¡¡planes¡£
In¡¡Fig¡£¡¡49¡¡A¡¡designates¡¡the¡¡upper¡¡and¡¡lower
planes¡¡of¡¡a¡¡Wright¡¡machine£»¡¡with¡¡the¡¡peculiar
rounded¡¡ends¡£¡¡The¡¡ends¡¡of¡¡the¡¡planes¡¡are¡¡so
arranged¡¡that¡¡the¡¡rear¡¡margins¡¡may¡¡be¡¡raised¡¡or
lowered£»¡¡independently¡¡of¡¡the¡¡other¡¡portions¡¡of
the¡¡planes£»¡¡which¡¡are¡¡rigid¡£¡¡This¡¡movement¡¡is
indicated¡¡in¡¡sketch¡¡1£»¡¡where¡¡the¡¡movable¡¡part¡¡B
is£»¡¡as¡¡we¡¡might¡¡say£»¡¡hinged¡¡along¡¡the¡¡line¡¡C¡£
The¡¡dotted¡¡line¡¡D¡¡on¡¡the¡¡right¡¡hand¡¡end£»¡¡shows
how¡¡the¡¡section¡¡is¡¡depressed£»¡¡while¡¡the¡¡dotted
lines¡¡E¡¡at¡¡the¡¡left¡¡hand¡¡end¡¡shows¡¡the¡¡section
raised¡£¡¡It¡¡is¡¡obvious¡¡that¡¡the¡¡downturned¡¡ends£»
as¡¡at¡¡D£»¡¡will¡¡give¡¡a¡¡positive¡¡angle¡¡at¡¡one¡¡end¡¡of¡¡the
planes£»¡¡and¡¡the¡¡upturned¡¡wings¡¡E¡¡at¡¡the¡¡other¡¡end
will¡¡give¡¡a¡¡negative¡¡angle£»¡¡and¡¡thus¡¡cause¡¡the¡¡right
hand¡¡end¡¡to¡¡raise£»¡¡and¡¡the¡¡other¡¡end¡¡to¡¡move
downwardly£»¡¡as¡¡the¡¡machine¡¡moves¡¡forwardly
through¡¡the¡¡air¡£
CONTROLLING¡¡THE¡¡WARPING¡¡ENDS¡£Originally
the¡¡Wrights¡¡controlled¡¡these¡¡warping¡¡sections¡¡by
means¡¡of¡¡a¡¡cradle¡¡occupied¡¡by¡¡the¡¡aviator£»¡¡so¡¡that
the¡¡cradle¡¡would¡¡move¡¡or¡¡rock£»¡¡dependent¡¡on¡¡the
tilt¡¡of¡¡the¡¡machine¡£¡¡This¡¡was¡¡what¡¡was¡¡termed
automatic¡¡control¡£¡¡This¡¡was¡¡found¡¡to¡¡be¡¡unsatisfactory£»
and¡¡the¡¡control¡¡has¡¡now¡¡been¡¡placed¡¡so
that¡¡it¡¡connects¡¡with¡¡a¡¡lever¡¡and¡¡is¡¡operated¡¡by
the¡¡aviator£»¡¡and¡¡is¡¡called¡¡Manually¡operated¡¡control¡£
In¡¡all¡¡forms¡¡of¡¡control¡¡the¡¡wings¡¡on¡¡one¡¡side¡¡are
depressed¡¡on¡¡one¡¡side¡¡and¡¡correspondingly¡¡elevated
on¡¡the¡¡other¡£
THE¡¡CURTIS¡¡WINGS¡£Curtis¡¡has¡¡small¡¡wings£»
or¡¡ailerons£»¡¡intermediate¡¡the¡¡supporting¡¡surfaces£»
and¡¡at¡¡their¡¡extremities£»¡¡as¡¡shown¡¡in¡¡sketch¡¡2¡£
These¡¡are¡¡controlled¡¡by¡¡a¡¡shoulder¡¡rack¡¡or¡¡swinging
frame¡¡operated¡¡by¡¡the¡¡driver£»¡¡so¡¡that¡¡the¡¡body
in¡¡swinging¡¡laterally¡¡will¡¡change¡¡the¡¡two¡¡wings
at¡¡the¡¡same¡¡time£»¡¡but¡¡with¡¡angles¡¡in¡¡dif
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