When did aviation originate? How aviation developed, information about the tools used in aviation and its historical development. History of aviation.
Aviation, is the science and art of operating powered aircraft. The term generally is restricted to the flight of heavier-than-air craft. In this article the history of aviation is reviewed.
Early History.
Man dreamed of flying for thousands of years before Orville Wright made the first successful powered flight in a heavierthanair machine over the sand dunes of Kitty Hawk, N.C., on Dec. 17, 1903. Greek, Egyptian, Assyrian, and Oriental mythologies are filled with references to man’s aspiration to conquer the air. Virtually all of these concepts of man’s flight involved imitation of the soaring flight of birds.
Among the early scientific explorers who seriously studied the problem of manned flight were Roger Bacon, English philosopher and man of science, who about 1250 made the first recorded proposâl” for a gasfilled balloon, and Leonardo da Vinci, Florentine artist and scientist, who published a detailed treatise on human flight in 1505 and developed many detailed designs for flying machines, including the basic concept of what is now the helicopter.
Discovery of the lighterthanair gas hydrogen in the 1760’s turned aeronautical thinking back toward Bacon’s balloon concept. The first successful balloons were built and flown by the French inventors Joseph and fitienne Montgolfier in 1783. The Montgolfier brothers used a large paper bag inflated with hot air for their early flights, which reached altitudes of 6,000 feet (1,800 meters). The knowledge of hydrogen combined with the development of soluble rubber soon led to the produetion of hydrogenfilled rubber envelopes. These continued as the basic lighterthanair formula until the 1930’s, when helium was substituted for hydrogen.
Development of the internal combustion engine provided a logical source of power for the gasfilled bags. The Brazilian Alberto SantosDumont first flew a powered lighterthanair ship in Paris in 1898, and two years later the first of Count Ferdinand von Zeppelin’s giant powered airships flew in Germany.
The century preceding the Wright brothers’ successful flights was marked by an inereasing interest in practical aeronautical science. Sir George Cayley in England, Clement Ader in France, Nicholas Mozhaisky in Russia, Samuel Pierpont Langley and Sir Hiram Stevens Maxim in the United States—all built heavierthanair flying machines that failed to fly. By the end of the 19th century a promising approach to powered flight had been developed through the successful gliding flights of designs conceived by Otto Lilienthal in Germany and Octave Chanute in the United States. A variety of glider designs by these two men made over 4,000 successful flights before Lilienthal was killed while testing a new rudder design; and it was through the glider activities, first of Lilienthal and later of Chanute, that two of the four sons of Bishop Milton Wright of Dayton, Ohio, became interested in flying.
The Wright Brothers.
Orville and Wilbur Wright were operating a successful bicycle manufacturing and repair shop in Dayton when they expressed their first formal interest in flight about 1899 by writing to the Smithsonian Institution in Washington, D.C., for suggested reading material on aeronautics. The Wrights eagerly read the articles by Lilienthal and Chanute recommended by the Smithsonian and entered into a correspondence with Chanute. This led to a significant personal and teehnieal relationship between the two brothers and the famous structural engineer.
The wright brothers’ first ambition was to build a mancarrying kite. After making inquiries of Chanute and the United States Weather Bureau for a suitable location, they settled on Kitty Hawk, N.C., where steady sea breezes and sand dunes combined to offer ideal conditions for gliding experiments. The Wrights built their first glider in the spring of 1900 and took it to Kitty Hawk in the fail. The glider, controlled by two ropes, was flown like a kite. It was built on the basis of data obtained from the writings of Lilienthal and Chanute and flew reasonably well on tether with a 50pound (22kg) payload of ehains.
Encouraged by these efforts, the Wrights returned to Dayton determined to build a much larger, mancarrying glider. This new glider was flown at Kitty Hawk in the fail of 1901 in the presence of Chanute and proved to be a failure in the air. It was during these unsuccessful experiments in 1901 that the Wrights became convinced that the Chanute and Lilienthal data contained major flaws. They therefore started off on their own basic experimentation on airfoils— their first major step toward successful powered flight.
During the winter of 1902-1903 they built, in their bicycle shop, a crude wind tunnel from ası old laundry starch box and obtained their first experimental confirmation that the data they had been using were wrong. Thereupon, they built a more efficient wind tunnel with an airstream propelled by a single cylinder gasoline engine, and they experimented with some 200 different airfoils. From these data they built a new glider that departed radically from earlier methods of achieving stability and control in the air. During the fail of 1902 they made a thousand flights with this glider at Kitty Hawk, surpassing all the previous performances of Chanute and Lilienthal. In the teeth of winds up to 36 miles (58 km) per hour they made successful gliding flights, and several glides went more than 600 feet (180 meters). Now sure they were on the right track and with confidence in their own data, the Wrights determined to build a powered machine for their 1903 experiments. The next nine months saw the bicycle business badly neglected as they wrestled with a variety of new problems posed by applying power to their 1902 glider design.
The first problem was the engine. The unsuccessful planes of Professor Langley and Hiram Maxim had been powered by steam engines much too heavy for their purpose. The Wrights’ analysis of the problem left them with specifications for an 8horsepower engine that would deliver 1 hp for each 20 pounds (9 kg) of engine weight. None of the gasoline engine manufacturers of the day cared to take the order, so the brothers were forced back on their own resources.
They had designed and built the engine for their wind tunnel. Now, with the help of their mechanic, Charles Taylor, they designed and built an engine that embodied such modern concepts as direct fuel injection into the cylinders, use of aluminum to save weight, and water cooling. The Wright engine weighed only 170 pounds (76.5 kg) and delivered 16 hp for the first 15 seconds at 1,200 revolutions per minute but then dropped to an output of 12 hp. Even so, it weighed 6 pounds (2.7 kg) less per hp than the original specification, which the professional engine builders thought was impossible to achieve.
The Wrights turned again to their wind tunnel and books on marine engineering to develop a propeller design. Drawing on their bicycle experience, they rigged a chain drive to carry power from the engine to the two pusher propellers.
All these new tasks postponed their arrival at Kitty Hawk until late in September 1903. Then a combination of bad weather and vexing mechanical problems delayed the first attempt at powered flight until December 14. On that day, with Wilbur at the controls, the Wright plane climbed too steeply and crashed at the foot of a dune after having been aloft just 3V2 seconds. It took two days to repair the damage and then, on December 17, Orville got his turn. He stayed in the air for 12 seconds and landed successfully some 120 feet (36 meters) from the takeoff point. The rest of the afternoon the brothers alternated at the controls and made three more flights, the longest of 59 seconds duration covering 852 feet (256 meters). Then another crash causing minor damage was followed by a gust of wind that tumbled the flying machine over and over and made further flying that year impossible.
That night Orville sent the following message to his father in Dayton: “Success four flights Thursday morning all against twentyonemile wind started from level with engine power alone average speed through air thirtyone miles longest 59 seconds inform press home Christmas. Orville Wright.”
Although the press was informed, only three papers in the United States printed the story, and reports of the Wright brothers’ flying achievements were greeted with press and scientific skepticism for several years after the first Kitty Hawk flights. The first complete account of the Wright flights was published in the March 1904 issue of the magazine Gleanings in Bee Culture.
The years immediately following the Wright brothers’ flights saw an extremely slow growth in aviation, primarily because of the skepticism of the press and scientific leaders that powered flight by man was possible. During 1904 the wrights designed a new model and logged only 45 minutes flying time. The next year, with the new model now flying out of Huffman’s pasture near Dayton, the wrights circled in banking and turning and stayed aloft for 38 minutes, covering 24 miles (39 km). They did no flying in 1906, concentrating on new engine design. In 1907 they made a triumphal tour of Europe during which they established subsidiary companies for the manufacture of their designs in England, France, and Germany.
Early Flight Records.
Alberto Santos-Dumont became the first to fly in Europe in 1906, using a boxkite style biplane. In the United States a formidable rival to the Wrights developeo from the Aerial Experiment Association financed by Alexander Graham Bell, inventor of the telephone, and headed by Glenn Curtiss, who was already famous as a designer and racer of motorcycles.
The era from 1908 to the outbreak of World War I was dominated by the air meet in which aircraft designers and pilots competed in speed, endurance, altitude, and acrobatics for cash prizes put up by newspaper publishers, wealthy aviation enthusiasts, and a growing number of aero clubs that were being formed all over the world. Aircraft were built of wooden frameworks, covered with doped canvas and braced by wires and turnbuckles. They were relatively cheap to build and repair, the engines being the most expensive item. Pilots had no cockpits but sat, exposed to the wind, braced by rudder pedals and control wheel. For many years no safety belts were used, and a high percentage of fatallties in crashes resulted from the pilot being pitched out of his plane. Goggles, cap worn backwards, and checkered Norfolk style jacket became the uniform of the pilots during that era. Fierce competition at the air meets produced constantly improving performance that soon enabled the airplanes to race successfully against the automobiles of that vint’age. Among the notable milestones of that era were Louis Bleriot’s first flight across the English Channel (1909); Walter R. Brookins’ altitude record of 6,175 feet, or 1,852 meters (1910); Glenn Curtiss’ flight of 152 miles (245 km) from Albany to New York in 2 hours 46 minutes flying time to win a $10,000 New York World prize (1910); and the first transcontinental crossing by an airplane—a Wright biplane piloted by Calbraith P. Rodgers (1911). It took Rodgers about 49 days, during which he survived 15 crashes, to fly from New York to Pasadena, Callf.
Both the Wright and the Curtiss organizations had teams of exhibition and racing pilots who eompeted for the big prize money. Air racing became the most exciting sport, and the names of the top pilots were as well known as those of baseball stars today. But crashes were frequent, and by the beginning of World War I few of the racing era pilots had survived.
Perhaps because Europe was drawing closer to a major war and its national leaders were more aware of the potential use of aircraft for military purposes, the development of aviation flourished more rapidly in Europe from 1910 onward than in the land of its inception.
The United States Army issued specifications for a military aircraft in 1907, specifying that it must be transportable by horsedrawn wagon. The Wrights were the successful bidders with their biplane model offered at $25,000 a plane. The first acceptance flights were made by Orville wright at Fort Myer, Va., just outside Washington, D.C. It was here on Sept. 17, 1908, that the first fatal military accident occurred. Orville Wright was piloting Lt. Thomas Selfridge, who, ironically, had been a designer for the rival Curtiss group. At an altitude of 125 feet (37.5 meters) control trouble developed. Orville glided down to about 50 feet (15 meters) when the biplane fell completely out of control and crashed. Orville was thrown clear of the wreckage, suffering a broken thigh and ribs, but Selfridge was pinned in the wreckage of the aircraft and killed.
The Wright biplane sold to the Army had a length of 28 feet (8.5 meters), a wingspan of 36 feet 4 inches (11.1 meters), and weighed 1,200 pounds (540 kg). It could reach an altitude of 140 feet (43 meters) and had a top speed of 44 mph (71 kph) and a range of 125 miles (200 km). It had a 30 hp f ourcylinder engine of the wrights’ own design and manufacture.
World War I.
By the time war broke out in Europe, the U.S. Army had only one aero squadron, consisting of 8 aircraft and 16 officers. The Navy also had become interested in Glenn Curtiss’ flying boat designs and Curtiss pusher designs with propellers at the rear of the wings, which proved their ability to take off from a specially planked surface on the deck of a battleship. In 1914, however, the Navy had only 9 planes and 21 engines for its aerial effort. A series of accidents with the Wright and Curtiss pusher designs put them into military disfavor, and the tractor design with the propeller in front became the standard just before the war.
By the end of 1915 only 100 aircraft, including both military and civil types, had been manufactured in the United States. However, in the 19131915 period many of the foundations were laid for the aeronautical development efforts of the next 30 years. The first aeronautical engineering course was established at the Massachusetts Institute of Technology about 1912 by Jerome C. Hunsaker, then a naval officer assigned to aircraft construction. The United States Weather Bureau began publication of a daily aviation weather map in 1914. The National Advisory Committee for Aeronautics, the spearhead of United States technical progress in aviation for the next 40 years, was created by an act of Congress in 1915.
At the beginning of World War I, France had the largest air force, with about 1,500 planes, followed by Germany, with 1,000 military aircraft. Britain lagged badly, with only a few hundred planes, including trainers. The outbreak of war plunged aviation into a forceddraft technical development that achieved more technical progress in three years than had been accomplished in the preceding decade. Aircraft speeds, which were about 60 mph (100 kph) at the beginning of the war, more than doubled to 145 mph (230 kph) for operational fighters in 1918. Altitude ceiling increased from about 14,000 feet (4,200 meters) in 1916 to over 30,000 feet (9,000 meters) by the end of the war. From the prewar aircraft, whose payload was usually only a pilot, a passenger, and gasoline, the useful load increased to more than 3,000 pounds (1,350 kg) in 1918 vintage bombers. Aircraft manufacturing plants and pilot training centers mushroomed in all the belligerent countries to provide a reservoir of facilities and trained personnel that gave the postwar growth of aviation much of its impetus.
From the beginning of World War I there was a bitter debate over the proper military function of the airplane. Most traditional military leaders felt the airplane was primarily a scouting weapon to extend the eyes and ears of the cavalry in locating enemy forces and positions, and it was in this role that the airplane operated during the first year of the war. German and French pilots flying unarmed reconnaissance planes waved to each other as they sped across opposing lines on their missions. Aircraft spotted enemy ground forces, took pictures of the terrain, and dropped propaganda leaflets. Gradually, as the character of the war changed into the bitter trench deadlock, the combative spirit of the airmen increased. Pistols and rifles were carried aloft to take potshots at enemy fliers. Small bombs ‘and grenades were added to aerial equipment to toss at likely targets on the ground. Breaking through the restrictions artificially imposed by military leaders, the airmen added the airplane to the arsenal of deadly military weapons.
By 1915 the French were experimenting with a machine gun mounted to fire forward through the propeller are. Heavy armor plate encased the blades. While firing a gun thus mounted, Lt. Roland Garros, a prewar aviation pioneer, shattered his propeller blades and was forced down behind German lines.
The Germans quickly sensed the importance of the French development and gave Anthony H.G. Fokker, a Dutchman whose services had been rejected by Britain and France before he settled in Germany, the job of developing a machine gun synchronized to fire through the propeller arc. Fokker solved the problem with a mechanical cam that stopped the machine gun from firing each time a propeller blade was in the line of fire.
German pilots flying planes equipped with the Fokker synchronized machine gun sallied out in force, driving Allied aircraft from the battle area. From this time onward the air in wartime would be a disputed area. Control of the air became a prize in itself and a necessary requisite for successful ground or sea operations. The French soon countered with a hydraulically operated machine gun synchronizer, and the air war flartAl into new fury.
Types of Military Planes.
As the war dragged on, three primary types of battle planes emerged as the primary lines of technical development. First came the scout or fighter aircraft designed to drive enemy aircraft from the sky and maintam control of the air. These were singleseater aircraft with the best performance available—starting out at about 90 mph (140 kph) top speed in the early war years and pushing closc to 150 mph (240 kph) before the war’s end. They were armed with a pair of forwardfiring machine guns. It was in this type of aircraft that the great aces of World War I fought and rolled up their record of kills. Baron Manfred von Richthofen of Germany topped the list of fighter pilots with 80 victims, followed by Maj. Rene Fonck of France with 75, British Maj. Edward “Mickey” Mannock with 73, Canadian Maj. William Avery Bishop with 72, and Capt. Ernst Udet of Germany with 62. The leading United States ace was Capt. Edward V. Rickenbacker, credited with destroying 21 aircraft and four balloons.
The fighter pilots preserved the last elements of the ancient chivalry of knights in combat during the bloody mass slaughter of trench warfare. When they were forced down behind enemy lines, the enemy air force entertained them as dinner guests before shipping them off to prison camps. When a fighter pilot was killed in enemy territory, the victors buried him with full military honors and dropped a note containing details of his demişe and a photograph of his grave on his squadron aerodrome. Even in the swirling dogfights between squadrons of fighter planes, the combat usually consisted of individual duels.
However, a German schoolteacher named Oswald Boelcke, turned fighter pilot, changed this style of combat. Boelcke was the originator of fighter tactics that saw flights and squadrons deployed so that they fought as a group rather than as individuals. Boelcke was killed after 43 victories, in a midair collision with a wingman, before he could fully apply his tactics in combat over the westeın front. But his leading pupil, Baron Manfred von Richthofen, put them into practice with his wing of redpainted Fokker triplanes and dominated the air over northern France for months with Boelcke’s tactics.
The continuing design series of Fokker dominated the German fighter planes. The most famous was his triplane, which was extremely maneuverable for dogfighting but short on range and level speed. The DVII model, which used metal tubing instead of wood, was the first cantilever wing combat plane and had outstanding performance characteristics. The DVIII Flying Razor was a highwing monoplane with a tapered wing. Only a few reached combat, but they easily outelassed the other 1918 vintage fighters over the western front. On the Allied side, the British Sopwith Camel and SE5 fighter planes, and the French Nieuport and Spad fighters, were the cream of their crop.
As the war settled down to the grim stalemate of the trenches, both sides sought means to surmount this obstacle and strike deeper at the roots of each other’s war effort. This led to the development of bombers, the second primary type of battle plane. The Germans raided London and other key English towns in Zeppelins, but the giant airships soon succumbed to the double menaces of British fighters and North Sea weather. They were supplanted by the twinengine Gotha bombers and later by the giant SiemensSchuckert Rl bombers with a wing span of 150 feet (45 meters) and engines located in the fuselage, where they could be repaired in flight.
The British retallated with raids on the industrial towns of the Ruhr and Rhine valleys with Handley Page biplane bombers, which could deliver a 1,650pound (750 kg) bomb load, and with the shorterranged de Havilland DH4 bombers, which operated against supply dumps, artillery concentrations, and other rear line targets. The French developed the Farman and Brequet bombers, while the Itallans used the giant Caproni triplane bombers, which had a wingspan of 130 feet (39 meters) and could carry 3,000 pounds (1,350 kg) of bombs. They operated from Itallan bases and penetrated deep into Austria and southern Germany on their raids.
The third speciallzed type of battle plane was the twoseater observation plane designed to photograph enemy terrain and observe troop movements, artillery concentrations, and supply dumps. Early in the war, captive balloons were used for this purpose, but they became too vulnerable to enemy fighter aircraft and were superseded by the observation plane protected by a covey of fighter aircraft. Many of the mass fighter combats over the western front were engaged in to control the sky for the operations of the observation planes.
United States in World War I.
The first Americans to fight in the air over Europe were volunteers who enlisted in the French Foreign Legion and in 1915 formed the Lafayette Escadrille. Later, after the United States entered the war in April 1917, the first contingents of United States Army pilots were assigned to the Royal Flying Corps and flew under the command of British and Canadian offîcers.
The United States air effort was dominated by the personallty and ideas of Brig. Gen. William (Billy) Mitchell, who was the first American aviator to reach the western front and who commanded the combat aviation units of the American Expeditionary Force during the final offensives of 1918. General Mitchell was an aerial strategist who saw far beyond the capabilities of the spruce and fabric planes he had to fly during World War I. Like the German Boelcke, he concentrated on developing tactics for using aircraft in large masses to achieve major strategic aims, rather than for aimless dogfighting. For the American offensives at St.Mihiel and in the Argonne in 1918 he organized all the aviation under his command into a strategic offensive. His first effort was to sweep the Germans from the sky over1the battlefield, thus denying them observation of American troop movements. He then turned his aerial offensive against the German rear areas to destroy their supplies and artillery and prevent reserves from moving into the battle line. These basic tactics of isolating the battlefield by aerial action were used effectively again in Wotld War II and the Korean War. Mitchell also prepared to deliver a largescale attack by paratroops and airborne infantry for an offensive planned in 1919 in much the same way that Allied troops hurdled the Rhine River barrier in 1945 by airborne assault.
Out of his experience in the brief but significant aerial action of 1918, General Mitchell developed the deepseated convictions that were to lead to his postwar crusade for the development of adequate military airpower. They also would lead to his courtmartial by the traditionallst element in the military leadership who, disputing the lessons of the western front, could not envision the airplane as anything more than a scouting force.
The United States entered World War I woefully weak in the air, with a strength of only 55 observation planes, 35 pilots, and 1,087 enlisted men. The performance of the aviation section of the Signal Corps on the Mexican border in support of Gen. John J. Pershing’s punitive expedition in 1916 had proved it weak in maintenance and operational reliability, as well as in combat potential. Although the Allies soon swamped Unite.d States factories with orders for aircraft and engines, most of the combat planes had to be of foreign design because there v*ere no modern American designs. The bulk of American design skill was concentrated on training planes and the engines for them. Among the foreign designs produced in the United States were the British de Havilland DH4 bomber, the Lepere French fighter, the Itallan Caproni triplane, and the French HispanoSuiza engine. The only Americanbuilt combat planes to see use in Europe before the Armistice were a few Daytonbuilt DH4S’s. United States fighter squadrons flew French and British planes exclusively in combat until the war’s end.
Stimulated by the huge wartime appropriations for aircraft that totaled $598,000,000 in 19171918, American manufacturers delivered 13,943 airplanes and 41,953 aircraft engines. United States designers produced some extremely good combat designs, but they were all too late to see service. These included the Curtiss18 fighters and the Thomas Morse MB3, both in the 150 mph class, and the Martin MB bomber, a twinengine giant of its era.
The first practical guided missile—the Bug— also was developed in 1918 by Elmer A. Sperry and Charles F. Kettering. It was built of papiermâche with wood framework and could carry a 300pound (135kg) bomb load automatically delivered on a target 40 miles (65 km) from takeoff. In concept and function it was the forerunner of the German Vl flying bomb of 1944.
From 1919 to 1939.
Aviation emerged from the war stili continııing its rapid technical development, and with large quantities of war surplus aircraft, trained pilots, and technicians, but no immediate prospects of absorbing them into peaceful pursuits.
The rapid technical growth was evident in the spectacular performance of a series of planes developed during the final years of the war. The fîrst transatlantic crossing by air was made in May 1919 by the U.S. Navy’s NC4 antisubmarine seaplane, with stops in Newfoundland and the Azores. The plane covered a distance of 3,396 nautical miles (6,289 km) from New York to Plymouth, England, in 53 hours 58 minutes. A month later a British VickersVimy bomber flown by Capt. John Aleock and Lt. Arthur Whitten Brown of the Royal Air Force crossed from Newfoundland to Ireland in the first nonstop transatlantic flight, taking 15 hours 57 minutes for the flight from coast to coast. Another VickersVimy flown by a Royal Air Force crew forged the fîrst aerial link between England and Australla in the fail of 1919.
A new altitude record of 33,113 feet (9,934 meters) was set in 1920 by Maj. Rudolph W. Schroeder of the U.S. Army Air Service in a Lepere biplane with a supercharged Liberty engine. The world speed record was pushed up to 178 mph (286 kph) by a Verville Packard plane piloted by Lt. C.C. Moseley of the U.S. Army, winning the Pulitzer trophy race for 1920.
However, both military and civil aviation were headed for the doldrums during the early 1920’s. Military pilots, stifled by the older leaders of the Army and Navy, were forced tâ fly obsolete war surplus types for many years. There was only a trickle of military funds to keep allve the continuity of technical development. Much of the aircraft airframe and engine industry evaporated af ter the war. Only a handful of dedicated men stuck to their trade of airplane building during the lean 1920’s. Among these men were Glenn L. Martin and his aides Lawrence Bell, Donald Douglas, and J.D. Kindelberger (each of whom eventually was to head a giant aircraft firm of his own), William E. Boeing in Seattle, Frederick B. Rentschler at the WrightMartin Company in New Jersey, Grover C. Loening, and a few others.
Civil aviation failed to grow significantlj/ duling the early 1920’s. A generation of ‘barnstormers,” equipped with war surplus Jennies powered by the Curtiss OX5 engine and the DH4 powered by the Liberty engine, eked out a precarious living at county fairs by racing, stunting, hopping passengers, and dispensing flying lessons. The Post Office Department attempted to operate airmail routes, but many of these soon were abandoned because they offered little improvement in service. A few courageous groups ventured into the airline business, but passenger carrying was restricted by the small size of the planes available.
Court-Martial of General Mitchell.
The major event during the early 1920’s was the sensational climax to the career of Brig. Gen. William Mitchell and the seeds it sowed for the development of military airpower during the next two decades. General Mitchell returned from his wartime experience in France an ardent crusader for the largescale development of airpower as the keystone of United States military policy. His first crusade was directed against the Navy, whose battleships he claimed were rendered obsolete by bomber aircraft. In 1921, with congressional approval, General Mitchell was given an opportunity to test his theories against a series of captured German vessels, including the superdreadnaught Ostfriesland, which had been unsinkable by British gunfire in the Battle of Jutland. General Mitchell’s bombers sank the German warships, including the Ostfriesland, in a spectacular demonstration of aerial bombardment by landbased Martin bombers, making their attack on the ships at sea off the Virginia capes. Two years later the Army Air Service fliers sank the obsolete United States battleship Virginia in four minutes and the New Jersey in seven minutes. But it was not until eight battleships of the United States Navy were sunk by Japanese aircraft in Pearl Harbor on Dec. 7, 1941, that this lesson really was learned by the battleship admirals of the U.S. Navy.
Demoted from assistant chief of the Army Air Corps and exiled to a minor post in Texas, General Mitchell refused to abandon his crusade and deliberately invited Courtmartial by pointing out the technical fallacies in the Navy’s illfated dirigible program. General Mitchell used his courtmartial in 1925 as a sounding board to carry the case for airpower to the American public and to bring attention to the obsolete policies of the Army and Navy. Although Mitchell’s military career was ended by his conviction, he stimulated public interest in the airpower situation. A series of congressional and presidential investigations eventually produced military and civil policies that revived aviation development during the 1930’s.
Achievements of the 1920’s.
The military aviators still were primarily concerned with stretching the performance of their equipment and demonstrating its capabilities to an apathetic public. Among the outstanding military achievements of this period were: the first nonstop transcontinental flight in 1923 by Lts. John A. Macready and Oakley G. Kelly, who piloted a Fokker T2 monoplane from New York to San Diego in 26 hours 50 minutes; the roundtheworld flight of four Douglas World Cruisers in 1924, piloted by Air Service officers, covering 27,553 miles (44,339 km) in 175 days; the first aerial refueling operations by two Army pilots in 1923; and an endurance record without refueling of 28 hours 35 minutes, established in 1925 by U.S. Navy Lts. C.R. Schildhauer and J.R. Kyle in a PN9 flying boat.
Among the other notable United States Navy achievements during this period were the first flight over the North Pole in 1926 by Lt. Comdr. Richard E. Byrd and his crew in a Fokker trimotor plane and the establishment of an altitude record of 37,995 feet (11,588 km) in 1927 by Lt. C.C. Champion, flying a Pratt & Whitney Wasppowered Apache.
Out of the ferment of the early 1920’s the technical and political developments emerged that were to pave the way for an undreamedof expansion of commercial aviation and new combat potential for the military air services during the 1930’s. On the technical side there were two major developments. One was the trend away from the biplane design, with its dragcreating mesh of struts and bracing wires, to the lowdrag, cantilever wing monoplane design. The other was the development of the radial aircooled engine. The latter proved to be so much more reliable and so much lighter than the watercooled designs that it provided a significant performance margin for successful commercial operations and improved military performance. Charles Lawrence developed the aircooled radial engine in the United States, initially, with its signiflcant development carried on by the Wright Aeronautical Corporation with its Whirlwind series and later by Pratt & Whitney Company with its Wasps and Hornets.
Politically, the sensations of the Mitchell courtmartial, combined with growing public concern over airpower, produced a series of legislative acts that laid the foundation for sound military and commercial aviation development. The Air Corps Act of 1926 raised the Army’s aviation to corps status and provided it with the nucleus of a professional officer corps of pilots and technicians. The Navy created °the Bureau of Aeronautics under Rear Adm. William A. Moffett and under his guidance laid down a program to develop aircraft carriers as a challenge to the battleship. In the commercial field the Kelly Act of 1925 took the Post Office Department out of the airmail business and opened it to bids from private contractors. The Air Commerce Act of the following year established a uniform system of licensing, thus reducing the anarchy of commercial aviation. It also authorized creation of a federal airways system using light and radio beacons to mark highways of the air.
Lindbergh’s Flight.
These elements of the explosive aviation development of the 1920’s were detonated by the spectacular nonstop flight of Charles A. Lindbergh from New York to Paris on May 2021, 1927. Lindbergh’s triumph was based on the combination of the Ryan monoplane (which Lindbergh named S pirit of St. Louis) and the Wright radial aircooled.. engine—the two technical elements that were to dominate the postwar renaissance of aviation. The $25,000 prize for the first New YorkParis nonstop flight was offered in 1920 by the Orteig brothers, Frenchmen who had built a fortune from American hotels. But it was not until the combination of the efficient monoplane design and the reliable and light aircooled engine was developed that even the most skillful and daring pilot could turn the trick. Lindbergh’s solo flight to Paris in 33 hours 20 minutes touched off an, aviation boom of such magnitude that even when its1 more ephemeral elements dissolved, the curve of civil and military aviation continued to rise.
The Lindbergh flight to Paris touched off a series of recordseeking flights that stretched over the next 10 years. Many of these were simple attempts to seek fame and glory for the participants, but others were solid efforts by technically skilled participants to push the parameter of aircraft performance to its maximum limits. For example, the transcontinental speed record, which stood at 21 hours 44 minutes in 1924 as a result of U.S. Army Lt. Russell L. Maughan’s famous dawntodusk flight across the United States in a Curtiss pursuit plane, was cut to 7 hours 28 minutes by Howard Hughes in 1937. In 1935, Hughes had pushed the world speed record to 352 mph (566.5 kph) in a plane of his own design and manufacture that set the transcontinental record. By 1933, Wiley Post had flown 15,596 miles (25,099 km) around the world solo in just 7 days 18′ hours, piloting the Lockheed Vega monoplane Winnie Mae, which now hangs with its Wasp “engine in the Smithsonian Institution.
But behind the spectacular façade of the record breakers, genuine and “phony,” who filled the newspaper headlines of the late 1920İS and early 1930’s, the firnı foundations of the United States bid for world leadership in both commercial and military airpower were being laid.
Commercial Developments.
Commercial aviation in the United States was stili in the cow pasture stage at the end of 1926, lagging far behind European airline developments which were spurred by strong government financial support. When Lester D. Gardner, editor of Aviation Magazine, made a 26,000mile (41,840km) air tour of Europe in 1926, he traveled a wellestablished commercial network that carried him through the busy airports of Croydon for London, Templehof for Berlin, Le Bourget for Paris, and to North Africa, Russia, and the Middle East. In contrast, the United States had only a trickle of airmail, carried in obsolete DH4 planes. A single dimly lighted airway stretched from New York to Cheyenne, Wyo., and there was nothing that honestly could be called an American commercial airline. A few shorthaul air express services and passenger charter operators were on the scene, but like the Post Office, they were plagued with inefficient and unreliable war surplus equipment. There was no air traffic control, no safety regulations, or aviation law.
Seven years later the United States boasted the busiest airport in the world. At Newark, N.J., the air terminal for New York City, airline traffic for 1933 surpassed the combined total of Croydon, Le Bourget, and Templehof for the same year. Commercial airports at Los Angeles, Chicago, and Camden, N.J. (serving Philadelphia), all were busier than any European airfield.
In 1933, United Air Lines was the largest United States air carrier, while the German Lufthansa dominated its field abroad. During 1933 the Lufthansa carried only 10 percent of the airmail tonnage and a little more than half the passenger volume of United, while the German transports flew only 40 percent of the route miles covered by United’s planes. Pan American Airways operated more multiengine transports in 1933 than the combined total for all European airlines, and four years later, Pan American Airways Clippers became the first to span both the Pacific and Atlantic oceans in airline operations.
This surge carried United States commercial aviation to world leadership, which it has never relinquished. The surge was based on a favorable governmental climate that offered airline opera^ tors an opportunity to make a profit on airmail transport and on subsidized passenger service during their growth period. Another factor was the technical progress that made carriage of profitablc payloads possible.
Technical Trends.
The technical trends of this era stili dominated commercial transport design until the advent of the gas turbine engine. It was in the early 1930’s that aircraft construction switched from the spruce, fabric, and plywood of the 1920’s to metal (mainly aluminum) as the dominant material. Propellers also were changed from wood to aluminum. The Ford allmetal trimotor design of the early 1930’s started the trend, but the third motor soon was abandoned as engine reliability improved. The twinengine Boeing 247 carrying 12 passengers, and the Douglas DC series with their lowwing monoplane designs became the new airliner standard. The DC1 flown by Daniel W. Tomlinson set a new transcontinental speed record of 11 hours 5 minutes in 1935. By 1936 its successor, the 21passenger DC3, had given the airlines reliable equipment with which they could begin to operate at a profit. The Douglas DC3 was the workhorse of commercial and military transport operations for nearly 20 years.
During this same period burgeoning technical development was pushed primarily by the airline market with development of precise navigation instruments and radio navigation aids. Blind flying instruments that enabled airliners to operate through heavy clouds and bad weather, controllable pitch propellers for better takeoff and cruising performance, and airtoground radio communications all combined to increase the safety and reliability of airline operations during the 1930’s. By 1939 the airlines of the United States were carrying close to 3 million passengers annually, and their service extended to every major city. Pan American World Airways had spanned both the Atlantic and Pacific and was operating extensively in Latin America—the forerunner of a large network of United States flag line international air services that blossomed after World War II.
Military Developments.
Military airpower, however, was making less progress against the traditional advocates of sea and land power. In the Navy the aviators were fighting primarily against the advocates of the battleship for the development of aircraft carrier striking groups. In the Army Air Corps the battle was not only against the landbound generals of the War Department but also against the battleship admirals of the Navy who fought successfully to limit the range of operations for landbased aircraft to within 300 miles (483 km) from the United States coasts until the eve of World War II.
During the early 1930’s the foundations of the aircraft carrier striking forces were developed by naval aviators, although early caTriers were simply converted cruisers. In the same period the Air Corps strategists pushed development of longrange heavy bombers.
In their concentration on longrange bomber development the Air Corps strategists neglected other fields, notably longrange fighter aircraft, that were to cause them considerable trouble in World War II. The Martin B10 twinengime bomber of the early 1930’s was the first truly modern bomber, using allmetal construction, lowwing monoplane design, and carrying relatively heavy bomb loads and defensive armament. its 250 mph (400 kph) speed was faster than that of the fighters of its day, adding further fuel to the arguments against building defensive fighter planes. By 1935 the first prototype Boeing B17 bomber had been delivered to the Air Corps for flight testing.
Although the prototype crashed shortly after takeoff on its initial test flight at wright Field near Dayton, Ohio, in July 1935, the Air Corps never lost its faith in the future of the big bomber. It continued to put most of its available procurement funds into pushing bomber development with the Boeing XB15 and the Douglas XB19, the latter being the largest aircraft in the world at the time of its flight testing in 1939. From this development emerged the production versions of the B17 fourengine Flying Fortress, just going into operational service in small numbers by 1941, and the later B29 longrange bomber, which proved decisive in the Pacific war.
While the Air Corps was concentrating on bomber development, it permitted fighter development to lag. One complicating factor was a policy decision to abandon reliance on the aircooled radial engine and concentrate on a liquidcooled design, because of lower frontal drag permitting more streamlined airframe designs. During the period of 19361941 the Air Corps turned its back on the aircooled engine for fighter craft only. But continued support by the Navy kept this type in production and available for the widespread Army and Navy use necessitated by world War II. Another complicating factor was the concept that fighters were to function only as shortrange interceptors. Consequently the long range needed later was neglected in fighter development.
The combination of a growing healthy commercial aviation and a military policy of continuous development of new types of aircraft put a solid floor under the aircraft manufacturing industry during the 1930’s. This was to become the foundation for the enormous wartime expansion of 19401944. Such firms as Douglas, Boeing, Lockheed, and Consolidated stabilized on the West Coast on a mixed militarycommercial market, while Grumman, Republic, Glenn L. Martin, Curtisswright, and United Aircraft grew into substantial industrial enterprises along the Atlantic seaboard.
By the late 1930’s the German Luftwaffe had again become a potent force in European skies. The Luftwaffe’s Condor Legion performed impressively in combat during the Spanish Civil War of 19361939. In the spring of 1939 a Messerschmitt BF109 fighter aircraft set a world speed record of 469 mph (754.8 kph). These events served notice that a new factor had entered the European airpower situation. Simultaneously, the Japanese were building a powerful naval air force, based on the U.S. concept of an aircraft carrier striking force.
World War II.
When the European war began in 1939 the Germans had the strongest air force in Europe, although it was designed not for the exercise of independent airpower strategy but for close support of armored and infantry divisions of their army. The Luftwaffe was strong in fighters and dive bombers but weak in medium bombers and devoid of heavy bombers. German “bombers lacked range, bomb load, and heavy defensive armament required for independent air strategy.
The French air force was large, but it consisted chiefly of obsolete planes. The Luftwaffe drove it from the skies by the spring of 1940.
The Royal Air Force (RAF) of Britain was developed primarily as a defensive weapon, although the doctrine of independent airpower was stili strong among the British airmen who originated it. The eightgun, high performance fighters of the RAF (the Hawker Hurricane and Supermarine Spitfire) were in the 350 mph (560 kph) class and had the edge over Luftwaffe formations operating near the edge of their range.
Both over Dunkerque and later, in the Battle of Britain, over the approaches to London, the RAF fighters scored decisive victories over the Luftwaffe in 1940. RAF Hurricanes and Spitfires inflicted such heavy losses on the Luftwaffe formations over England that daylight operations were abandoned, and the bombing attack on London switched to the cover of darkness. Never again did the Luftwaffe really threaten England from the air, and large scale offensive efforts were not renewed until the availability of the pilotless Vl and V2 missiles of 1944. If the Luftwaffe lacked the proper equipment for a sustaiııed, successful air offensive against England, so did the RAF lack sufficient range and the right type of bomber equipment to carry the air battle deep into the German industrial complex.
into this European air deadlock the U.S. Army Air Forces moved in 1943 with a new type of equipment and strategic concept. The equipment was the fourengined, highaltitude medium bomber symbolized by the Boeing B17 Flying Fortress and the Convair B24 Liberator, both designed to deliver five tons of bombs on precise enemy industrial targets in daylight in the face of enemy fighter and antiaircraft opposition. The doctrine was strategic airpower, carrying the war through the air to the heart of the enemy’s war effort and wrecking his factories, transport system, and will to resist.
The U.S. Eighth and Fifteenth air forces, charged with executing this attack, ran into many difficulties during their early offensive against Germanheld Europe. Development of a sound strategic target system required a longer effort than anybody anticipated. It was not until the aircraft factories, synthetic oil refineries, and the transportation system were given top priority that the German war machine began to grind to ^ halt. Better navigation and bombing methods were needed. Bloody losses were inflicted by German flak and fighters until the defensive armament of the medium bombers was increased and longrange escort fighters entered the fray.
The appearance of the North American P51 Mustang (after the war redesignated F51—for “fighter”), with enough range to escort bomber formations to any target in Germany and sufficient performance to destroy enemy fighters encountered over these targets, was a decisive turning point in the air battle for Europe. The combined AngloAmerican air offensive, with the RAF carrying the burden at night and the Fortresses and Liberators bombing by day, finally crushed the German war effort.
In the Pacific a different but no less decisive pattern of airpower developed. Initial Japanese successes in the strikes on the United States battleships at Pearl Harbor, the British in Malaya, the Dutch in Indonesia, and the United States in the Philippines all were predicated on skillful use of naval airpower based on the aircraft carrier’s longrange striking force. Fortunately United States Navy carriers were absent from Pearl Harbor during the Japanese surprise attack and were therefore available to blunt the enemy’s advance through the Pacific in a series of extraordinary naval battles in the Coral Sea and off Midway in the spring of 1942. Both these battles were waged completely by both sides with naval carrierbased aircraft. Both sides suffered heavy losses in aircraft and carriers, but the Japanese were beaten decisively and lost the cream of their naval aviators.
Although the Standard Japanese navy fighter, the Zero, was superior in performance to the Navy and Army fighters the United States used at the beginning of the Pacific war, the Japanese lacked the technical development effort to support a steady growth of new, improved aircraft types. By the middle of 1943, new United States types, such as the Grumman Hellcat, the Vought Corsair, and the Lockheed Lightning, had wrested air superiority from the Japanese. The airpower pattern during the first phase of the Pacific war saw the gigantic Navy carrier task forces spearheading the advance of amphibious landing forces to capture Japanese island strongholds. This developed into a gigantic interdiction campaign whereby the sea and air communications of the Japanese empire were severed without assaulting major bastions of enemy strength, such as Truk and Rabaul. The climax of this campaign was reached in the capture of the Mariana Islands and the appearance of the Boeing B29 Superfortress—the first heavy bomber to see combat.
Combination of the Mariana bases and the Superfortress’ range put the Japanese home islands under the shadow of United States strategic airpower. As in the air over Europe, the strategic doctrine required considerable refinement before it was successful. Highaltitude bombing proved unsuccessful because of the high winds. High explosive bombs also proved ineffective. To do this job properly, the B29’s had to use incendiary bombs that gutted the wooden cities of Japan, and they went down to 5,000foot altitudes to confuse the enemy defense.
With the appearance of the atomic bomb that seared Hiroshima on Aug. 6, 1945, followed three days later by another dropped on Nagasaki, the Japanese war effort came to an end, and the Japanese empire surrendered without a single land battle in the homeland.
Commercial Aviation Since 1945.
The years following World War II were marked by the expansion of commercial aviation on a scale never dreamed of by the most optimistic prophets of the prewar era; a fierce pace of technological development that pushed aircraft performance beyond all prewar predictions; and a bitter battle for supremacy in nuclear airpower between the United States and the Soviet Union.
Initially, commercial operations were dominated by surplus war transports—the Douglas DC3, the fourengine Douglas DC4, the Lockheed fourengine Constellation, and the Curtiss twinengine C46. However, United States manufacturers were quick to convert their wartime engineering and manufacturing experience into design and production of a more modern series of airliners designed for maximum economy of operation.
Douglas produced a larger and faster version of its fourengine design, the DC6, which proved to be the most successful of the transport designs in the decade following the war. This series was built in both passenger and cargo versions and later extended, by the addition of more powerful engines, into the DC7, with cruising speed up to 365 mph (587 kph) and nonstop range of 5,000 miles (8,000 km). During this same period, Lockheed enlarged and refined its tripletailed Constellation design.
While the Americans continued to develop their tried and true line of pistonpowered transports, the British struck boldly in the new direction of jet propulsion. The first fruits of this British effort came early in 1952, when British European Airways inaugurated the first commercial jet service with the Vickers Viscount powered by four Rolls Royce gas turbine engines driving propellers. The Viscount proved extremely successful in airliner service in Europe, Canada, and Australla and made the first penetration of the American transport market by a foreign product. The second British venture into the jet transport field was the de Havilland Comet, powered by four turbojets. The Comet was the first turbojetpowered aircraft to go into regularly scheduled airline service when it began operating on the British Overseas Airways Corporation routes to South Africa in 1952. The Comet program came to a temporary halt in 1954 as a result of two accidents over Italy in which the crew and passengers of two BOAC Comets were killed by what appeared to be midair explosions. Subsequent investigation by the Royal Aircraft Establishment disclosed that the pressurized cabins of the Comets had failed when metal fatigue occurred around the corners of the cabin windowf. The resulting exp!osive decompression demolished the aircraft in the air. Corrections for these structural problems were made by de Havilland, and by the 1960’s many Comet transports were operating on international air routes.
Russia was the second nation to have regular jet airliner service. The Tupolevdesigned TU104 began operating in 1956, and the TU134, TU154, and YAK140 (all with rearmounted turbofan engines) are medium and shortrange successors to the TU104 series. The USSR has a large family of jet transports, from the longrange TU114 to the Antonov AN10, which can operate from grass and dirt fields. In the 1960’s the Soviets unveiled the giant fourjet Ilyushin 62, designed to carry 180 passengers nonstop over intercontinental distances, and the even larger AN22, which could carry more than 700 passengers. A Mach 2.2 supersonic transport, the TU144, was also being developed.
The United States was late in entering the jet transport market; the Boeing 707 was not in regular service until 1959. By the 1960’s, however, the United States dominated the international jet transport field and was expanding rapidly into air cargo service as well. The Boeing 737 and Douglas DC9 extended transport operations to the shorthaul field. Boeing and Lockheed were also building a “jumbo” jet capable of carrying 700 fullyequipped combat troops and military equipment such as tanks. A supersonic transport that could fly from New York to Paris in about three hours, at 1,800 mph (2,900 kph), was planned for service in the mid1970’s.
The French also were successful in the jet transport field, with their twinjet Caravelle, introduced in the 1950’s and designed for the shorthaul market. The placing of engines at the rear of the fuselage on the Caravelle was widely copied in other jet transport designs. In the early 1960’s the French and British formulated a joint development program for a supersonic transport named the Concorde. This giant deltawinged plane, built by a consortium of British and French firms with the financial support of both governments, is designed to carry 110 passengers on the transatlantic route at Mach 2.2, or 2.2 times the speed of sound—about 1,500 mph (2,400 kph).
Military and Research Craft Since 1945.
Development of jet fighters in the late 1940’s doomed the pistonpowered bombers to obsolescence and made their replacement with jet bombers that could fly higher and faster a necessity. The jet bombers were forced to sacrifice range, due to high fuel consumption of jet engines, in return for the higher speed and altitudes offered. As a result, the technique of aerial refueling was revived and transformed from an occasional stunt into a routine operation.
During the immediate postwar period the United States concentrated its military airpower resources on the creation of a longrange striking force armed with atomic bombs. This organization, eventually known as Strategic Air Command (SAC), initially was equipped with Boeing B50 bombers, an improved version of the wartime B29. By 1948, SAC had in operation the first truly intercontinental aerial weapon system in the Convair B36. This bomber was the largest military aircraft ever built, weighing some 400,000 pounds (180,000 kg) on a fully loaded takeoff. It was powered by six piston engines and four jet engines, which produced a total of more than 80,000 horsepower. The Convair B36 could fly 10,000 miles (16,000 km) without refueling, dropping an atomic bomb load at the halfway point of its flight.
The Korean war stimulated military aircraft construction throughout the world, and the 1950’s saw the development of the supersonic jet interceptor and the subsonic jet bomber. In the United States, the jet interceptors developed from the North American Mach 1.5 Super Sabre through the first generation of Mach 2 fighters included the Convair F106 allweather, deltawinged interceptor and the Lockheed F104G Starfighter. Another Mach 2 interceptor and strike fighter, the McDonnell F4H, was powered by two afterburning turbojets and carried a radar operator as well as the pilot. Machine guns and cannon were superseded by radar and infraredguided, airtoair missiles on these fighters.
A basic new advance of the early 1960’s was the variablesweep wing, a hingemounted wing that enabled the pilot to alter the basic design of his aircraft while in flight. For low speeds the wing is fully extended; for supersonic performance the wing is swept back, a configuration capable of Mach 2.5 speeds. Convair built the Air Force’s Flll variablesweep fighterbomber.
United States bomber development was concentrated on the Boeing sweptwing B47, powered by six turbojets and capable of only mediumrange operations without refueling. About 1,500 B47’s were built for SAC by a production consortium of Boeing, Douglas, and Lockheed, and they formed the backbone of the U.S. nuclear striking force in the mid1950’s. They were joined in the latter half of the decade by the Boeing B52, which eventually had a nonstop range of 12,000 miles (19,300 km) without refueling, and was armed with nuclear missiles. A total of 700 B52’s were manufactured, the B47’s being phased out of service beginning in 1961. The first supersonic bomber, the Convair B58, entered operational service with SAC in 1960. The deltawinged craft could fly at Mach 2 for sustained periods. However, production of both the B52 and the B58 ceased in 1961 as intercontinental ballistic missiles began to take over the major role in the nuclear striking force.
The United States later became the first nation to fly military aircraft at Mach 3. This speed was attained in 1965 by the Lockheed A11 reconnaissance aircraft and the North American XB70A bomber. The All went into service with SAC in 1966, but the XB70 program was canceled after two prototypes were built. One XB70A was destroyed in 1966 in a midair collision with a fighter aircraft.
In Britain, aircraft manufacturing also expanded as a result of the Korean conflict in the 1950’s, and exports of Britishmanufactured jet engines, fighters, transports, and trainers became the largest single source of export income for the United Kingdom. In the field of jet interceptors the English Electric’s Lightning P.l joined the rank of Mach 2 interceptors. As for bombers, Britain developed its Vbomber force of Vickers Vallants, Handley Page Victors, and Avro Vulcans as its nuclear weapon delivery system and equipped the Vulcan with airtosurface missiles to extend its striking range. all the Vbombers were subsonic and were scheduled to be superseded in the 1970’s by supersonic aircraft.
The appearance of the Bussian sweptwing, jetpropelled MIG15 fighter over Korea served surprising notice of the swift progress that the Soviet Union had made with its aircraft development in the jet field. The MIG15 was an excellent highaltitude interceptor. The Soviet Union later produced several types of Mach 2 interceptors, including the Mikoyandesigned, deltawinged MIG21 and MIG23 and a Yakovlev allweather craft—all of them carrying airtoair missiles guided by radar or heatseeking sensors. By 1965 the USSB was flighttesting a deltawinged fighter capable of Mach 3 speeds.
The USSB developed a large fleet of subsonic bombers in the mid1950’s, eonsisting of the twinjet Badger mediumrange bomber and the fourjet Bison heavy bomber. The Badgers later were modifîed to carry longrange airtosurface missiles instead of bombs and have been exported to a number of other nations. The Bison, however, was phased out of service after a limited production run, due to performance deficiencies.
Two types of supersonic bombers were displayed for the first time by the Soviets in their 1961 Tushino air show. They were the 200footlong Bounder with a thin delta wing, powered by four huge turbojets, and the smaller Blinder, powered by two aftmounted jets and equipped with an airtoground missile. Both were in the Mach 2 speed range. Andrei Tupolev, dean of Soviet aircraft designers, also built a large turboproppowered, longrange bomber known as the Bear, which is being used extensively for longrange reconnaissance beyond the Soviet borders.
In France the aircraft industry recovered from the effects of World War II and made rapid technical progress in the 1950’s and 1960’s. The French Dassault Mirage III joined the ranks of Mach 2 interceptors, and in the early 1960’s the Mirage IV bomber became the basis of France’s strategic retallatory force and delivery system for its own nuclear weapons. The Mirage IV required refueling from a Boeing jet tanker force, purchased from the United States, in order to reâch most of its required strategic targets. The German aircraft industry began its postwar resurgence in the early 1960’s, largely by building United States and French designs under license, but also by starting to develop its own designs across a broad spectrum from jet transports to verticaltakeoff military planes.
Military aircraft thus reached the level of Mach 2 speeds in the early 1960’s, while transport aircraft were flying in the 500600 mph (8001,000 kph) speed range. At the same time, however, research aircraft continued to push back the frontiers of flight by reaching speeds of Mach 5 and altitudes above 350,000 feet (106,000 meters). Spearheading this drive to expand man’s range of flight was the United Statesdeveloped series of experimental research aircraft ranging from the X1 to the X15. It was just 50 years after the Wright brothers made their first faltering flights at Kitty Hawk that a young U.S. Air Force captain, Charles E. Yeager, flew the Bell X1A rocketpowered research plane to a maximum speed of 1,650 mph (2,650 kph), equivalent to 2V2 times the speed of sound. (Yeager had been the first pilot to fly at the speed of sound in the original Bell Xl.) In the mid1950’s, later models in the series of research planes doubled the Xl’s achievements.
But all these advances paled in the face of the assault on the frontiers of flight made by a group of United States military and NASA (National Aeronautics and Space Administration) pilots, who flew North American’s X15 to speeds beyond 4,000 mph'(6,400 kph) and to altitudes above 350,000 feet (106,000 meters). The research explorations of the X15 carried its pilots into the lower fringes of space, and the men were therefore awarded astronaut wings.
