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SOME AVIATION GROWTH EVENTS
M Leroy Spearman*
NASA Langley Research Center
Hampton, Virginia 23681
Abstract
The growth of aviation since the first flight of
a heavier-than-air powered manned vehicle in
1903 has been somewhat remarkable. Some of
the events that have influenced this growth are
reviewed in this paper. This review will include
some events prior to World War I; the influence
of the war itself; the events during the post-war
years including the establishment of aeronautical
research laboratories; and the influence of World
War II which, among other things, introduced
new technologies that included rocket and jet
propulsion and supersonic aerodynamics.
The subsequent era of aeronautical research
and the attendant growth in aviation over the past
half century will be reviewed from the view
point of the author who, since 1944, has been
involved in the NACA/NASA aeronautical
research effort at what is now the Langley
Research Center in Hampton, Virginia. The
review will discuss some of the research
programs related to the development of some
experimental aircraft, the Century series of
fighter aircraft, multi-mission aircraft, advanced
military aircraft and missiles, advanced civil
aircraft, supersonic transports, spacecraft and
others
-------------------------------------
* Senior Technical Specialist
Systems Analysis Branch
Associate Fellow, AIAA
Copyright (c) 2002 by the American Institute of
Aeronautics and Astronautics, Inc. No copyright
is asserted in the United States under Title 17,
U.S. Code. The U.S. Government has a royaltyfree
license to exercise all rights under the
copyright claimed herein for Governmental
purposes. All other rights are reserved for the
copyright owner.
AIAA 2002-0172
Introduction
Orville and Wilber Wright were credited with
achieving the first flight of a heavier-than-air,
powered, man-carrying airplane at Kitty Hawk,
North Carolina, USA on December 17, 1903.
This event marked the beginning of a dramatic
history of aviation growth. The airplane has
changed from a curiosity to a vehicle of many
uses that include transportation, exploration,
recreation and warfare. The growth in aviation
has occurred in many countries around the world
and has been fostered by the native talent of
individuals as well as by the exchange of
information between countries and by the import
and export of hardware. Driving factors in this
growth have included the innate curiosity of
man, an inherent desire for adventure, the quest
for economic benefits, and the feeling of need for
security and superiority.
Discussion
The Beginnings. The Wright's achievement of
manned, powered, controlled, heavier-than-air
flight in 1903 was preceded by many years of
thinking, planning, and working. The Wright's
could also benefit from the works of several
other's. One of the first to concentrate on the
development of a heavier-than-air, fixed-wing
flying machine was Sir George Cayley of
England. In 1853, Cayley made a glider in
which it is said that his unwilling coachman
made what was probably the first flight in a
manned, heavier-than-air craft. While Cayley
was laying much of the foundation for modern
aircraft, he could not provide what he called a
prime mover - a suitable lightweight engine.
Among other innovative glider designers was
Otto Lilienthal, a German, who, in the 1890's
built and flew many successful hang-gliders.
Lilienthal was killed in 1896 when a wind gust
caused the glider on which he was flying to stall
and crash. Lilienthal did record his work so that
others might benefit from his experience. One
follower, Percy Pilcher in Scotland, constructed
several promising gliders in the late 1890's and
was working toward a powered machine when a
crash ended his career. In the United States, a
French-born American, Octave Chanute, became
interested in aeronautics and flight. He wrote
2 2
several journal articles on the development of the
flying machine and in1894 the articles appeared
in book form entitled Progress in Flying
Machines. Chanute and his associates did design,
build and fly several modified versions of the
Lilienthal-type glider. In about the same period
of time in the late 1800's another American
scientist, Samuel Pierpoint Langley became
convinced that powered flight was achievable.
Langley did not experiment with gliding flight
but with models powered with rubber bands at
first and then with steam engines. In November
1896, his steam-powered Aerodrome No. 6
successfully demonstrated powered flight when
it flew for three-quarters of a mile before running
out of fuel. The Wright brothers were aware of
Langley's experiments and wrote for more
information on his work. The Wright brothers
also wrote to Chanute and described some of
their experiments to him. This was the beginning
of a friendship during which Chanute provided
assistance and encouragement to the Wright's.
The Wright's studies also included the work of
Lilienthal.
While gliding flight demonstrated manned,
heavier-than-air flight, a satisfactory engine to
provide powered flight was needed. Some early
attempts for powered flight were made using
steam engines to drive a rotor or propeller but
none were successful in achieving sustained,
controllable flight. Langley did proceed from his
powered flight success to an attempt to fly a
manned version of the Aerodrome. He was
dissatisfied with steam power because of the low
power-to-weight ratio and had changed to an
internal combustion gasoline engine similar to
that being used on early automobiles. An attempt
was made on Oct.7, 1903 to achieve mannedpowered-
flight with the Aerodrome but it
crashed immediately due to a problem attributed
to the catapult launch mechanism. Another
attempt was made to fly the manned-powered
Aerodrome on Dec. 8, 1903 but again a crash
attributed to the catapult launch occurred. Nine
days later on Dec.17, 1903, Orville Wright
successfully achieved powered flight at Kitty
Hawk, NC. TheWright's had also turned to the
gasoline-fueled internal combustion engine and
had built their own engine based on the type
being developed for automobiles.
Manned-powered-flight was now a reality.
Man's innate curiosity had sparked the desire to
fly. Gliding flight had demonstrated the theory
of aerodynamics and lead to means of stability,
control, and balance. The development of the
lightweight internal combustion reciprocating
engine completed the approach to manned flight.
The reciprocating engine is still in use today and
was essentially the only type of airplane engine
for more than 40 years before the turbojet engine
was perfected.
The Concept Spreads. A French artillery
commander, Captain Ferdinand Ferber became
interested in flying because of the exploits of
Lilienthal and Chanute. In corresponding with
Chanute, Ferber learned about the Wright's and
began to correspond with them. Through his
writings and lectures, Ferber had a significant
influence on the advancement of flight in France.
One early flyer in France was Brazilian-born
Alberto Santos-Dumont who built and flew
gasoline-powered airships in the late 1800's,
turned to gliders and then to powered airplanes.
He earned the credit for making the first
powered, manned aircraft flight in France in
1906. The Wright's finally demonstrated their
airplane to the U.S Army and sold the first
airplane to the Army in 1908. The Wright's also
demonstrated in France to an enthusiastic
audience. The first heavier-than-air machine to
fly in England, the Army Aeroplane No.1, flew
in October 1908. The machine, similar to the
Wright design, was created by Samuel Cody, an
American-born naturalized Briton. The first
heavier-than-air flight in Germany was a 1908
demonstration by J.C.H. Ellehammer, a Danish
visitor. The German's were intrigued with the
rigid airships being built by Count von Zepplin
and paid little attention to the airplane. In an
effort to catch up, however, the German's were
soon to borrow from France and from other's.
Germany capitalized on the talent of Anthony
Fokker, a Dutchman who came to Germany to
study engineering. In Russia, a young designer,
Igor Sikorsky, was experimenting unsuccessfully
with helicopters. He then turned his attention to
large, fixed-wing airplanes and produced what
would become a forerunner of large bombers and
commercial airplanes. Latter Sikorsky left Russia
and came to the United States where he was to
successfully produce helicopters. Following the
initial success of the Wright Brother's, little
attention was given to the airplane in the United
States. Another U.S. designer, Glenn Curtiss,
was becoming well known and a Curtiss airplane
was the second airplane to be bought by the U.S.
Army in 1911.
3 3
The Airplane atWar. The idea that an airplane
might be used in warfare was adopted in the
early 1900's by European countries where war
was imminent. The French, the most air-minded
in Europe, had 254 airplanes in the Army by
1912. Two prominent French designers's at the
time were Louis Bechereau and Edouard
Nieuport. Bechereau designed the Deperdussin
racer in 1913 that was the first airplane to have a
monocoque fuselage. Later he designed the Spad
fighter of World War I fame. Nieuport was to
become the designer of the famous Nieuport
fighters of World War I. The British, after
acquiring Army Aeroplane No.1, were slow in
getting into military aviation. At the urging of
such politicians as Winston Churchill, the Royal
Flying Corps was established in April 1912.
Some Among the British designers of the era
where A.V. Roe, Geoffrey de Haviland, and
T.O.M. Sopwith, each of who made important
contributions to British airpower. In Germany
the efforts of Fokker lead to the monoplane,
biplane, and triplane fighter airplanes of World
War I fame. The U.S. showed less interest in
developing air power than did the European
nations since the threat of war was less ominous.
However, some interesting developments did
take place. The Army produced the world's first
bombsight and conducted live bombing tests
from aWright Flyer in 1911. In the winter of
1910-1911, the U.S. Navy conducted the first
shipboard takeoff and landing with a Curtiss
airplane. Curtiss airplanes were also used for
catapult launch testing. In 1911, Curtiss
produced a practical seaplane. With wheels
attached to the seaplane, Curtiss also
demonstrated the world's first amphibian. Curtiss
went on to build a watertight fuselage and
produced the world's first flying boat.
The U.S. was slow in building airpower. When
war broke out in Europe in August 1914 the U.S.
had a total of 23 airplanes for military use. In
contrast, France had 1400, Germany had 1000,
Russia had 800 and England had 400. By 1915,
the U.S. was producing the Curtiss JN-4 Jenny
that was used primarily as a trainer. Some
European airplanes were also manufactured in
the U.S. as an aid to the war effort and this
provided valuable experience to American
industry. In the World War I era, the U.S
acquired several European airplanes including
those of Spad, Nieuport, Sopwith, deHaviland,
and Breguet. American airplanes, in addition to
the Curtiss Jenny, included those of Thomas-
Morse, Packard-Le Pere, Standard, and Martin.
In the final days of World War I, Russia, in
the midst of a revolution was also accumulating
foreign aircraft and engines from various sources
including French, German, British, Italian and
Dutch. Soon after the war, the Russians also
obtained the rights to build the U.S. Liberty
engine. These acquisitions were of great value to
the newly formed Soviet Union in establishing a
base in aviation technology.
Between World War I and II. During the
1920's and 1930's many nations were developing
indigenous airplane types for both military and
civil use. Among the producers in the U.S. were
Curtiss, Boeing, Douglas, Martin, Lockheed,
Keystone, North American, Consolidated, Ryan,
Grumman, Bell, Vultee, Republic, Northrop,
Vought, Sikorsky, Berliner-Joyce, Brewster,
Stearman, Beech, Cessna, Fairchild, Seversky -
in Great Britian producers included DeHaviland,
Bristol, Avro, Handley-Page, Fairey, Hawker,
Supermarine, Armstrong-Whitworth, Blackburn,
Westland, Saunders-Roe, Gloster, Boulton-Paul,
Short, Bristol - in France producers included
Leo, Breguet, Dewoitine, Farman, Amiot, Potez,
Loire, Bloch, Morane-Saulner, Latecoere,
Nieuport, Hanriot - in Germany producers
included Focke-Wulf, Heinkel, Dornier, Arado,
Henschel, Junkers, Messerschmitt, Fieseler,
Blohm and Voss - in Italy producers included
Caproni, Savoia-Marchetti, Fiat, Breda, CANT,
Macchi, Piaggio - in Japan producers included
Mitsubishi, Kawaski, Nakajima, Aichi, Showa,
Kawanishi, Hiro - in the Netherlands producers
included Fokker, Koolhoven - in the Soviet
Union producers included Antonov, Beriev,
Ilyushin, Lavochkin, Lisunov, Guryevich,
Mikoyan, Myasishchyev, Petlyakov, Polikarpov,
Sukhoi, Tupelov, Mil, Yakovlev, Bratukhin,
Kamov, Kalinin .
Some technology transfer between nations
occurred in the 1920's and 1930's through the
interchange of hardware. Junkers of Germany
operated a plant in the Soviet Union from 1923
to 1927 as a way for Germany to overcome some
of the restrictions imposed by the Treaty of
Versailles and as a way for the USSR to
accelerate their aircraft technology in areas such
as the use of duralumin in the design and
construction of metal, cantilever wings. Some
European designed airplanes found a place in the
growth of U.S. aviation - for example, the Dutch
Fokker T-2, a single-engine, cantilevered highwing
monoplane was used by the Army Air
Service and made the first non-stop flight across
4 4
the U.S. in 1923. The Fokker C-2 trimotor
transport, also used by the Army Air Service,
was used by Admiral Byrd in a flight over the
North Pole in 1926 and by the Army in the first
California to Hawaii flight in 1927. The Fokker
trimotor also saw early airline service in the U.S.
preceding the Ford Trimotor.
Thus a considerable amount of aviation
technology was transferred between nations in
the 1920's and 1930's through the interchange of
hardware. Another source of aeronautical
technical information was beginning to become
prominent during the 1920's. This was the
creation of aeronautical research laboratories by
many governments for the purpose of achieving
preeminence in aviation. In the United Stares,
the National Advisory Committee for
Aeronautics (NACA) was created by an act of
Congress in 1915 and the first NACA wind
tunnel was running at Langley Field, Virginia in
June 1920. In Russia, the Central Aero-
Hydrodynamic Institute (TsAGI) was
established in December 1918. In Great Britain,
the Royal Aircraft Establishment (RAE) was
begun and, in France, a research center was
started at Villacoublay. The NACA was quite
prolific in the time period between World War's
II and I in producing reports of investigations in
many areas of aeronautical research. Among the
results reported were those related to airfoil
sections; drag cleanup; high lift devices; the
NACA cowling; the engine supercharger;
stressed-skin construction; cantilevered wings;
retractable landing gear; enclosed cockpit;
propellers; stability and control; boundary layers;
dynamic stability; flying qualities and so on.
These developments were directed toward
increased efficiency; increased speed; increased
safety and comfort; increased utility and
productivity.
Civil aircraft development in the U.S. was
delayed byWorld War I. Some airplanes used in
early airline service were open cockpit, singleengine
biplanes such as the Douglas M-2 and the
Boeing Model 40. Among the first of the
dedicated airliners was the Ford 2-AT, singleengine,
all metal, high-wing monoplane with an
enclosed cabin. This was followed by the Ford
4-AT, all-metal, tri-motor with an enclosed cabin
for 11 passengers (the author of this paper made
his first flight on a Ford Trimotor at the age of
16.) Before the trimotor was produced, Henry
Ford's interest in aviation was noted in the
development of a small, 350-pound, roadable,
single-place aircraft referred to as the "sky
flivver". At least three versions of the flivver
were built and flown but it never reached the
public. Other early civil transports included the
Boeing Model 80-trimotor biplane and the
Curtiss Condor twin-engine biplane. In the
1930's some transports using more advanced
technology began to appear. One of the these
was the Boeing Monomail which first flew in
1930. The Monomail was a single-engine design
that had a smooth, low, cantilever, all-metal
monoplane wing, a cowled engine and a
retractable landing gear. This was followed in
1933 by the Boeing 247, a twin-engine design
with cowled supercharged engines, hydraulically
controlled variable-pitch propellers, a low allmetal
cantilever monoplane wing and a
retractable gear. Also in 1933, Douglas produced
the DC-1 that was followed by the DC-2 and
DC-3. These were all-metal designs with twincowled
engines, a low cantilever monoplane
wing, retractable gear, and variable-pitch
propellers. The DC-3 was faster than the 247
and carried more passengers and thus was able to
capture most of the domestic air transport market
by 1940.
A notable transfer of technology occurred in
the mid 1930's when the U.S. permitted Soviet
Union technicians to visit the Douglas Aircraft
Company to examine the revolutionary DC-3
airplane. Subsequently, manufacturing rights
were granted to the USSR where the airplane
was produced under the direction of B.P.Lisunov
as the Li-2. The Li-2 was soon placed in military
and civil service where it remained until well
into the 1940's.
In the 1930's, several clean streamlined
airplanes were produced in the belief that there
was a market for a small, high-speed transport.
Included in this category were the Lockheed
Vega and Orion, Northrop Alpha and Gamma,
Vultee V-1A, and the Lockheed10/14/18 family.
Another event in the 1930-1940 time period
was the flying-boat activity. These relatively
large aircraft were primarily to support the
oceanic routes of Pan American Airways. They
included the Sikorsky S-38, S-40, S-42, Martin
M-130 and Boeing 314. The flying boat concept
was later replaced by large, new land-based
airplanes.
Over 800 civil aircraft types were certified by
the CAA in the U.S. from the mid 1920'5 to the
5 5
mid 1950's. Among these were airplanes from
Aeronca, Arrow, Beech, Bellanca, Bird, Boeing,
Budd, Buhl, Cessna, Culver, Curtiss, Douglas,
Erco, Fairchild, Fleet, Fokker, Ford, Gee-Bee,
Great Lakes, Howard, Inland, Kellett. Kinner,
Laird, Lockheed, Loening, Luscombe, Martin,
Monocoupe, Mooney, Northrop, Piper, Pitcairn,
Porterfield, Rearwin, Republic, Ryan, Sikorsky,
Spartan, Stearman, Stinson, Swallow, Taylor,
Travel Air, Verville, Waco and many others.
Military aircraft of various types were under
development in the U.S. between World War I
and II. Biplanes were prevalent in the1920's as
the U.S. was following World War I designs.
Army aircraft of that period included the
Consolidated primary trainers, the Curtiss PW-8
Hawk family, Boeing PW-9, Martin MB-2, the
Keystone bombers, Curtiss Condor, Curtiss O-1
and A-3, Douglas O-2, O-25 and O-38. The
Boeing Company, in a private venture, began the
development of a new biplane fighter in 1928 by
changing from the liquid-cooled engine of the
PW-9 to an air-cooled radial engine. The
airplane was purchased by the U.S. Navy as the
F4B-1 shipboard fighter. Based on enthusiastic
Navy reports, the Army tested the airplane and
bought it as the first of a long line of P-12's.
Monoplane designs became more prevalent in
the 1930's with the expectation that the
performance would exceed that for biplanes. An
early Boeing design designated XP-9 had a high,
body-mounted, strut-braced wing. The XP-9 had
an all-metal structure and a semi-monocoque
fuselage that was to set the pace for future
designs. The wing location limited the pilot's
visibility and the airplane was not produced. The
next monoplane effort by Boeing was the XP-15
which was essentially a P-12 with the lower
wing removed. The XP-15 was never produced.
The next Boeing monoplane design was the
P-26, which had a wire-braced low wing, an
open cockpit and a fixed gear. The P-26 was
accepted and was a front-line fighter until the
early 1940's. The follow-on fighter's to replace
the P-26 were the SeverskyP-35 and the Curtiss
P-40. Some monoplane observation airplanes
produced by Douglas were the O-43 and O-46.
New monoplane bombers that appeared were the
Boeing B-9 and the Martin B-10.
Once again in the 20th century, warfare was to
play a part in the growth of aviation. In 1939, the
United States had an air strength of about 1700
airplanes of which only about 800 could be
considered first- line. These were primarily
outdated Douglas B-18's, Curtiss P-36's, and
Northrop A-17's. By contrast, the British had
about 2000 first-line airplanes. French air power
had deteriorated badly following World War I
and the French had adopted a homeland defense
policy to prohibit invasion that was based on
heavily fortified fixed ground bases such as the
Maginot Line. In Germany, where a military
buildup had been underway, the Luftwaffe had at
least 4000 essentially new airplanes. While the
Western world was debating over the German
buildup, another unusually large buildup was
going on almost unnoticed on the small islands
of Japan. The Japanese Air Force had about 2100
airplanes in 1937 and Japan was building two
aircraft carriers yearly in the late 1930's. The
German might was unleashed in Europe in
September 1939 and the Japanese attacked the
U.S. in December 1941.
The U.S. airpower continued to grow in the
late 1930's and early 1940's. Among the
airplanes that appeared were the Seversky P-35,
the Curtiss P-36 and P-40, the Boeing B-17 and
B-29, the Consolidated B-24, the North
American B-25, the Douglas A-20, the Douglas
A-26, the Martin B-26, the Bell P-39, the
Lockheed P-38, the Republic P-47, Northrop P-
61, and the North American P-51. American
industry accelerated to meet the wartime
demands. A prewar rate of 2000 airplanes per
year was up to 4000 airplanes per month by
1943. In the years from 1940 to 1945, the Air
Forces accepted almost 230,000 airplanes
The rapid growth in aviation was paced by a
growing need for an expansion of the research
effort. The NACA laboratory at Langley Field
was being stretched to the limit by the late
1930's. To aid in expanding the research effort,
new NACA research centers were established in
California (Ames in 1939) and in Ohio (Lewisnow
Glenn in1940). During the World War II
years, the workload changed and increased.
Attention was turned to the short-term problems
of airplanes already in production as well as to
exploring new fields of knowledge for those
airplanes still under design. During the years
from 1941 to 1944, the NACA laboratories
worked on 115 different airplane types with
spectacular results. Fighter speed, altitude, and
maneuverability were increased; buffet, stall and
spin problems were cured; bomber range and
payload was increased. Many outstanding
wartime airplanes were based on fundamentals
6 6
developed by NACA - such as airfoil sections;
cooling methods; high lift devices and so on.
Many of the wartime developments were also to
be used in commercial airplanes.
The American designed and built airplanes of
World War II were generally produced in
response to Army requirements. One exception,
however, was the North American P-51. This
airplane came about in response to a British
search for a fighter airplane to replenish the
dwindling Royal Air Force fighter strength. One
of the American companies approached by the
British, North American Aviation, Inc.,
undertook the design of the NA-73 airplane that
was produced in 117 days. The airplane used a
newly developed NACA laminar flow low-drag
wing section and a radiator ingeniously
positioned for low drag. The airplane was at first
ignored by the U.S. Army but was later to be
tested, accepted, and procured and, as the P-51
Mustang, became one of the outstanding fighters
of its day. First powered with a U.S. Allison
engine, the airplane was equipped by the British
with a Rolls-Royce Merlin engine, which
resulted in substantial increases in speed, range,
and altitude.
Another type of technology transfer accelerated
the growth of aviation in the Soviet Union.
Under the Lend-Lease program the Soviets
received over 18,000 airplanes - including the
Bell P-39 Airacobra and Curtiss P-40 Tomahawk
from the U.S. as well as some British Spitfires
and Hurricanes. In addition, the Soviets received
machine tools and factories including an
aluminum rolling mill; 2.25 million tons of steel;
400,000 tons of copper; and 250,000 tons of
aluminum (equal to 2 years of production at
1945 Soviet rates). All of these materials
permitted the Soviets to change from wooden to
metal airplanes late in the war.
Post World War II. - Much transfer of aviation
technology followed the end of World War II.
The Soviet Union, for example, began to study
captured and interned airplanes of both friend
and foe. One example was the exploitation of an
American Boeing B-29, three of which had made
forced landings in the Far East in 1944. A
Tupolev design team dismantled the B-29 and
copied the components and in 1947 the Soviet
copy, designated the Tu-4 (NATO Bull), was
shown in the Tushino Air Show. The Soviets
acquired much in the way of airplane design and
jet engine technology from the Germans. More
jet engine technology was acquired from the
British. The Soviets produced two British jet
engines under license. Thus the early Soviet jet
aircraft were powered by German and British
engines.
Further growth in commercial transports
began in the late 1930's and continued into the
1950's after an interruption caused byWorld
War II. Douglas had begun the development of
the DC-4, a 4-engine enlarged version of the
DC-3. The airplane entered military service as
the C-54. Lockheed developed the 4-engine
Constellation that also saw military service.
Other civil derivatives of the military were the
Boeing 307 Stratoliner 4-engine transport
developed from the B-17 bomber and utilizing,
for the first time, a pressurized fuselage. Boeing
also developed the 377 Stratocruiser a 4-engine
transport derived from the B-29 and B-50
bombers. The 377 had a twin-lobe 2-level cabin.
Following the war, in 1945, a team of American
scientists visited Europe to survey the state of
technology related to aviation. Soon large
quantities of scientific information was flowing
in to the U.S. In addition, a number of scientists
and technicians from Germany and Italy came to
work in the U.S. Probably the most impressive
new technology had to do with high-speed
aerodynamics and included data on jet and
rocket propulsion and on airframe shaping. Jet
propulsion for airplanes was under development
in Germany (von Ohain) and in Great Britain
(Whittle) in the 1930's and 1940's. The German's
were flying jet-propelled airplanes before the end
of the war (He-178, Me-262) and the British
twinjet Gloster Meteor was in service by the end
of the summer in 1944. The U.S. began the
secret development of a jet airplane in 1941
using an American version of the Whittle engine.
The airplane, the Bell P-59 Airacomet first flew
in October 1942.
The increase in airspeed made possible by the
jet engine lead to studies of airplane shapes with
reduced drag. One method was through the use
of wing sweep that would delay the onset of
compressible flow. Wing sweep had been
thoroughly studied in Germany. Basic airfoil
theory for swept and yawed wings by Dr.
Adolph Betz was published in 1935. Based on
the work of Betz, a low-speed wind-tunnel study
of the aerodynamic characteristics of swept and
yawed wings of various planforms was
undertaken at NACA Langley in 1944 - a study
7 7
to which the author of this paper was assigned.
This testing included planforms that were swept
back, swept forward, skewed, M-shaped,
triangular, rectangular and trapezoidal.
Some flight results for sweptback wings were
also obtained at NACA-Langley in 1947 using
the Bell L-39 research airplane. The L-39 was a
Bell P-63 modified to accommodate a swept
wing. The use of wing sweep in many countries
was to have a pronounced effect on the design of
aircraft for years to come. The first operational
swept-wing fighter airplane in the U.S. was the
North American P-86 that flew in October 1947.
The airplane began its life in 1944 as the
straight-wing Navy jet XFJ-1 Fury. As the
swept wing data became available, the design
evolved to the 35 degree swept wing.
Further growth in civil transports occurred
following the war with the application of jet
propulsion and wing sweep. The Boeing 707, the
first jet transport in the U.S., flew in 1954. The
4-jet, swept-wing design was a private venture of
the Boeing company based on the B-47 and B-52
swept-wing, jet bombers. The Douglas DC-8
was the second U.S. 4-jet swept wing transport.
Convair also produced a 4-jet swept wing
transport but production was limited because
Boeing and Douglas took the market.
Another approach to low-drag wings was the
use of delta shaped planforms with a highly
swept leading edge and a low thickness ratio.
Research on delta wing designs had been done in
Germany by Lippisch. Lippisch came to the U.S.
after the war and, working with the Air Force
and Convair, aided in the design of the tailless
delta airplane XF-92A which, in turn, lead to the
Convair F-102, F-106 and B-58 delta wing
airplanes. Many delta wing designs have been
developed in many other countries.
Further studies of the use of wing sweep lead
to the concept of variable sweep to combine the
low-speed advantages of low-sweep with the
high-speed advantages of high sweep into one
airframe. The concept lead to the development
of the Bell X-5 variable sweep research airplane.
Further impetus for variable sweep research
came in the mid 1950's when the British designer
Barnes Wallis shared his concept of a variable -
sweep airplane, the Swallow, with John Stack of
NACA-Langley. This lead to a series of wind
tunnel studies of the use of variable sweep on
transports, fighters and bombers. Among the
purposes envisioned were for the commercial
supersonic transport; the Navy combat air patrol
(CAP); the Tactical Air Command (TAC) low
altitude penetration; and the multipurpose
commonality airplane directed by Secretary
Robert McNamara for the Navy and the Air
Force - the Tactical Fighter Experimental (TFX)
which lead to the F-111. While the fundamental
purpose of developing a multi-service airplane
for the Air Force and the Navy was not
successful in the TFX program, there have been
other cases where commonality was achieved.
Examples are the Boeing F4B Navy fighter and
P-12 Army fighter; the McDonnell F4H Navy
fighter that was later adopted by the Air Force as
the F4.
The research airplane program that was begun
in the late 1940's proved to be an effective way
to advance the growth of aviation insofar as
actual flight hardware is concerned. Before the
advent of transonic wind tunnels. Early testing in
the transonic range was sometimes done with
free-flight rocket models; with the wing-flow
technique; and with the transonic-bump
technique. Early transonic data were obtained for
what was to become the X-1 airplane by testing a
half-model mounted on a curved bump on the
floor of the Langley High-Speed 7-by-10-Ft.
wind tunnel. When new hypersonic, supersonic
and transonic tunnels became available,
experimental data was obtained to accelerate the
flight research program as well as the
development of various types of missiles. launch
vehicles and spacecraft.
Advances in the understanding of supersonic
aerodynamics was underway in the 1950's with
the era of the 'Century Series' airplanes. The
distribution of volume and weight with most
high-speed jet designs was such that problems of
inertia coupling and longitudinal and directional
stability and control were encountered. The
attainment of low drag was also a concern.
These concerns lead to the development of the
area rule for drag improvement and various tail
arrangements for stability and control
improvements.
The development of aircraft after World War II
proceeded at a rapid rate. New missions were
developed that required new aircraft types. At
the same time, new types of aircraft were
developed that suggested new missions. The
advent of the high-speed computer has changed
the design and analysis cycles and, when
properly used in conjunction with experimental
8 8
techniques, the development of aviation systems
should become more accurate.
In the late 1950's and early 1960's, the quest
for still further increases in productivity for civil
transports continued. Attention was given toward
increasing the speed or increasing the size of
aircraft. Supersonic research had been underway
at NACA following World War II. A research
program on the supersonic commercial air
transport (SCAT) began at the renamed NASA
in1959 and over a period of about 7 years studies
were made of about 40 configurations. In 1963 a
National Supersonic Transport (SST) Program
was created and the research continued. An
industry competition to develop a SST was won
by Boeing/General Electric in 1966. The Boeing
design was plagued with problems and through a
host of technical, economical, ecological, and
political concerns, the U.S. SST program was
cancelled in March 1971.
In the same time period that the supersonic
transport studies were underway, other studies
were being conducted by industry and the
airlines to develop a larger subsonic transport.
These studies were aided by an Air Force request
for a large, long-range, logistic transport that
resulted in the C-5. Lockheed won the C-5
competition and Boeing turned their attention
toward the development of the 747. The 747
retained the 4-engine, swept-wing design of the
707 but introduced the first of a new generation
of wide-body jumbo jets. The 747 entered
service in 1970 and continues in service to this
day. Other jumbo jets that followed were the
McDonnell-Douglas tri-jet DC-10 and the
Lockheed tri-jet L--1011. Other jet transport
have entered the market such as the Boeing 757
and 767 and several Airbus models. Only one
supersonic aircraft has entered the commercial
transport market thus far - the British-French
Concorde that has been in service since1976.
Epilogue
Mankind has been upgrading the means and
methods of transportation since time began.
Methods of moving on land and water have been
progressively improved for years. Progress in
moving through the air has primarily been
achieved just in the past century. While flight
with lighter-than-air vehicles was accomplished
earlier, it was the achievement of manned flight
with a heavier-than-air powered vehicle that set
the course of air transportation. Gliding flight
was first mastered but the invention of a
lightweight engine and propeller system is what
it took to really get man off the ground. Since
that event occurred in December 1903, aviation
technology has grown significantly. The growth
has been fostered by the interchange of ideas and
people between many countries. The use of the
airplane in warfare has caused rapid growth in
aviation technology. A very significant event
was the introduction of jet propulsion. The
propeller-driven airplane was limited by the
rotational speed of the propeller and jet
propulsion open the way for a whole new bred of
high speed aircraft. Jet propulsion coupled with
improved design methods and with improved
construction techniques have provided aircraft
with capabilities that far exceed what might have
been expected at the time of the Wright brothers
flight in 1903. And the future, of course, is yet to
unfold.
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Spearman, M. Leroy: The Evolution of the
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