Subscribe now for full access and no adverts
In the space of an average lifetime, American military aircraft changed beyond recognition. General Henry ‘Hap’ Arnold, chief of the United States Army Air Forces during World War II, had learned to fly in 1911 in the Wright brothers’ pioneering aviation school. By the time he died in 1950, his successor could call on a new generation of jet-powered fighters, together with bombers capable of delivering an atomic bomb all the way to the Soviet Union. How was this transformation achieved, and what obstacles had to be overcome along the way?
Uncertain beginnings
Military aviation before World War I was primitive, underfunded, and dangerous. The fledgling air service was part of the Army Signal Corps – a subordinate status resented by some pilots, while others lacked the confidence to demand institutional independence. A more pressing issue was the hazardous nature of pilot training in the early years. The first aircraft trialled by the Army was a wood, canvas and wire-braced Wright Flyer biplane, powered by a frail 35hp engine with a skid undercarriage. For much of the year, the planes were based at the Wright brothers’ flying school at Dayton, Ohio, but in winter they had to be disassembled and moved by rail to the gentler climate of Georgia.
The early years of flight saw a debate between advocates of alternative positions for the plane’s engine. In the ‘pusher’ mode, typical of the first airframes, the pilot and passenger sat together in front of the engine – a potentially dangerous configuration, since, in a nose-down crash, they were likely to be crushed as the engine fell forward on to them. By 1914, the tractor design, in which the propeller pulls the plane through the air, was being recognised as broadly safer and more efficient.
Typical of the second type was the Curtiss JN biplane, which became the standard US trainer from 1915. Stable and easy to fly, the ‘Jenny’ was used on the first US military operation with an aerial dimension. This was a March 1916 expedition organised in response to a cross-border raid into New Mexico by Mexican revolutionaries. The experience demonstrated the Jenny’s shortcomings. The aircraft were plagued by mechanical failure and maintenance problems in the harsh desert climate, and struggled to reach the expedition’s forward position. They also proved unable to muster the power to overfly Mexico’s 12,000-foot Sierra Madre mountain range. The expedition commander General John Pershing later described the pilots as having ‘too often risked their lives in old and often useless machines they have patched up’.
The Aviation Division of the Signal Corps, as it was known when the US entered World War I in April 1917, was less technologically advanced than the equivalent forces of European allies. Industry struggled to meet the sudden rise in demand for machines. US manufacturers developed a standard engine, the Liberty engine, which could be adapted to fit a range of aircraft. The Aviation Division’s preferred type was the De Havilland DH.4, which became known as the Liberty Plane after the engine had been installed. By the time it reached the front in August 1918, however, the pace of change in aircraft design was such that it was practically obsolete. As a result, American forces relied heavily on readily available French aircraft, notably the Nieuport 28 and the SPAD S.XIII.
Progress towards equipping the force between the wars was slow. In the early 1920s, the twin-engined Martin MB-2 biplane (renamed the NBS-1 or Night Bomber Short- range) became the first US bomber to be produced in large numbers. With a range of 400 miles and a bombload of 2,000lbs, it was used by Billy Mitchell, the pioneering US aviator and army officer regarded by many as the father of the US Air Force, to demonstrate the ability of aerial bombing to sink warships off the Virginia coast.
The 1920s saw some useful innovations. The first aerial refuelling exercise, potentially extending aircraft range, took place in June 1923. But change was limited by a combination of budgetary constraints and technological conservatism. Resources were wasted on the experimental ‘Barling Bomber’, a large triplane that could carry 5,000lbs of bombs. It was so under- powered that it could not fly over the Appalachian Mountains on a trip from Ohio to Washington DC. In 1929, the base commander, one ‘Hap’ Arnold, ensured that this embarrassing legacy machine was consumed in a fire at the storage facility.
By the end of the decade, the standard bomber was the Curtiss B-2 Condor, whose performance was similar to that of the Martin NBS-1. The Army continued to use biplane fighters through the 1930s. The last of these to join the service, the Boeing P-12 E and F variants, had a metal fuselage but retained the wooden wings of earlier models.
The bombing war
The darkening international environment gave new urgency to the need to develop more effective aircraft. Long-range heavy bombers were increasingly seen as the key to national security. In 1934, the Air Corps set out requirements for a new bomber which went well beyond the capability of any US plane at the time: it was expected to fly at 10,000 feet at a speed of 200mph with a range of 2,000 miles.
The solution offered by Boeing turned out to be one of the best-known aircraft of World War II: the B-17 Flying Fortress. When it first took to the air in July 1935, it was far ahead of the competition. The B-17’s all-metal construction, multiple defensive gun positions, and futuristic design captured the imagination of the press and public. Powered by four turbo-supercharged radial engines, the B-17E, which entered service in 1941, had a top speed of 318mph and a 3,200-mile range. It could carry a 4,000lb bomb load. Observers expected that it would be able to fight off the improved enemy fighters of the time, such as the Messerschmitt Bf 109. Its rugged construction certainly enabled it to take a great deal of punishment.
From the end of 1941, the B-17 was joined by the Consolidated B-24 Liberator. Although it had a lower ‘ceiling’ than the Fortress, it had a higher cruising speed. The deep, box-shaped fuselage of the B-24 could carry double the B-17’s bomb load. It also had the edge in terms of range, making it indispensable as a provider of long-distance air patrols in the Battle of the Atlantic. But it was less heavily defended and more vulnerable to air- and ground-fire on missions over Germany.
The Norden bombsight, which used an analogue computer to calculate a bomb’s trajectory based on changing flight conditions, with a gyroscope to aid stability, helped to improve bombing accuracy on daylight operations. However, claims that it could ‘deliver a bomb into a pickle barrel’ were wildly exaggerated. In reality, it placed an estimated 32% of bombs within 1,000 feet of the target, from an altitude of 21,000 feet.
Meanwhile, the bomber crews were increasingly vulnerable as German radar improved and new fighters were introduced from mid-1942 – the upgraded Messerschmitt Bf 109G and Focke-Wulf Fw 190. The skies became more hazardous as fighter production increased and Luftwaffe forces were redeployed from the Mediterranean to concentrate on home defence. Groups of B-17s and B-24s flew in close formation in defensive ‘boxes’. These had the advantage of maximising firepower but were hard to manoeuvre. Both bomber types had a blind spot in the forward firing position, so German pilots learned to attack them head-on rather than from the side or above.
Finding a fighter with the range to escort the bombers deep into the Reich proved challenging. The heavily armed Republic P-47 Thunderbolt was excellent in high-altitude combat, but had to turn back on the western edges of Germany. The P-38 Lockheed Lightning, with its distinctive twin-boom airframe, had greater range than the Thunderbolt. It performed well in the Pacific theatre but was prone to engine trouble at high altitudes over Europe.
The solution came towards the end of 1943 in the form of the North American P-51 Mustang. Once its Allison engine had been replaced by a higher performance Rolls-Royce Merlin, with drop tanks added, it had a range of more than 1,600 miles. With a top speed of 440mph and the first-rate visibility afforded by its bubble canopy, it was arguably the best fighter of the war. Mustangs proved to be effective as ground-attack fighter-bombers as well. By the end of the war, they had destroyed 4,950 enemy aircraft – the highest number for any USAAF plane in European skies.
In the Far East theatre, a radically different kind of bomber came into service in spring 1944. The Boeing B-29 Superfortress looked quite unlike any of its predecessors. This giant silver plane’s 141-foot wingspan was 20 feet longer than the entire distance of the Wright brothers’ first flight four decades earlier. It was capable of carrying up to 20,000lbs of bombs – several times the capacity of the B-17 – and had a top speed of 350mph and a 3,250 mile range. It featured pressurised crew areas and was defended by remotely controlled machine-gun barbettes.
The B-29 was the most advanced piston-engined aeroplane of the war, but its production process was complex: a total cost of $3 billion made it more expensive than the Manhattan Project to build the atomic bomb. Its engines were dogged by mechanical problems – the commander of 21st Bomber Command in the Pacific, Curtis LeMay, recalled that ‘B-29s had as many bugs as the entomological department of the Smithsonian Institution’. Once it came on stream, however, the B-29 proved itself in devastating low-level incendiary attacks on Japanese cities. Then, most famously, it carried the atomic bombs dropped on Hiroshima and Nagasaki in August 1945. Post-war, the B-29 remained in service in the early years of the Cold War, as the only aircraft capable of delivering a nuclear bomb to strike the Soviet Union.
B-29s from 500th Bombardment Group, 73rd Bombardment Wing of Twentieth Air Force, drop incendiary devices over Yokohama, Japan, 29 May 1945.
World War II workhorse: the C-47 Skytrain
The Douglas C-47 Skytrain, known as the Dakota in the Royal Air Force and Commonwealth services, was probably the most recognisable US aircraft to a British audience. Developed from the DC-3 airliner, it was a highly effective military transport plane, used by several Allied nations as well as the USAAF. It could accommodate 28 paratroops or 6,000lbs of supplies, and was also used as a glider tug. The C-47 served in numerous theatres, from the Normandy landings to Arnhem, and from the Rhine crossing to the jungles of New Guinea and Burma. An airworthy example operates as part of the Battle of Britain Memorial Flight, based at RAF Coningsby in Lincolnshire.
Into the jet age
The US was slower than Britain and Germany to develop jet-powered aircraft. As USAAF chief, ‘Hap’ Arnold brought British engineer Frank Whittle’s turbojet engine to the US and promoted research into its application to fighter design. The initial result was the unimpressive, single-seat, twin-jet-engine Bell P-59 Airacomet, which first flew in October 1942. During the war, the USAAF concentrated mainly on established technologies that would be of immediate use.
This approach changed rapidly after the end of World War II. The first viable US jet fighter, the Lockheed F-80 Shooting Star, entered service in 1945. Although capable of almost 600mph, making it faster than any piston-engined contemporary, it was outclassed by Soviet MiG-15s in the Korean War and was superseded by the North American F-86 Sabre. More than 100mph faster than the Shooting Star, the Sabre proved itself an effective dogfighter. In 1954, the appearance of the North American F-100 Super Sabre gave the newly created USAF its first fighter capable of supersonic speed in level flight. By the end of the decade, it had been joined by other supersonic craft, including the Lockheed F-104 Starfighter, a high-performance machine often described as a missile with a man in it.
The most dramatic advances were in the shift from piston-engined to jet bombers. The successor to the B-29, in service from 1948, was the Convair B-36 Peacemaker. Almost twice the size of the Superfortress, and with a range of 10,000 miles, it could carry 72,000lbs of bombs. It was a curious hybrid, with six Pratt & Whitney radial engines supplemented by four turbojets – known to crews as ‘six turnin’, four burnin’’. It never took part in any combat missions, although its reputation must have played a part in deterring Soviet expansionism before intercontinental ballistic missiles (ICBMs) became available at the end of the 1950s.
The future lay with the development of all-jet powered bombers. The first of these was the six-engined, swept-wing Boeing B-47 Stratojet, which could carry 20,000lbs of bombs. Rising international tension following the outbreak of the Korean War in 1950 made its production urgent. Its maximum speed of 600mph gave it an edge over the B-36, although it possessed less than half the range, necessitating the use of forward bases or aerial-refuelling facilities.
The Stratojet was challenging to fly. Early versions required additional support from booster rockets on take-off, and a tail-chute was applied to slow the type on landing. But the B-47 filled a gap at a time of continuous crisis. It is an indicator of the speed of post-war aircraft development that, although heavier than any World War II plane, it was designated as a medium bomber.
By the mid-1950s, both the B-36 and the B-47 were becoming outdated. With a maximum speed of 435mph, the former was vulnerable to improved Soviet fighter aircraft. The Stratojet would have been rendered powerless had the US lost access to its infrastructure of forward bases. But a formidable replacement was now available.
The Boeing B-52 remains in use today, making it the world’s longest-serving warplane. Its official name was the Stratofortress, but USAF personnel more commonly called it the ‘Buff’ – short for, in its more polite version, the ‘Big Ugly Fat Fella’. Powered by eight jet engines mounted in underwing pods, the B-52 could carry up to 70,000lbs of bombs for 8,800 miles. Over the eight years of US military involvement in Vietnam, the B-52 dropped almost 3 million tons of bombs.
The B-52 stood at the front line of national defence in the most dangerous period of the Cold War, when military planners expected to have just 15 minutes’ warning of an impending Soviet attack. In the late 1950s, one-third of Strategic Air Command’s fleet were on ground alert at all times, fully fuelled and armed. From 1961, under Operation Chrome Dome, nuclear-armed B-52s were in the air on continuous airborne alert, ready to act if orders ever came through to unleash Armageddon. The practice was not without risk. In January 1966, a B-52 collided with an air tanker while refuelling off the Spanish coast, causing the loss of four hydrogen bombs and triggering an enormous search and clean-up operation.
An aerial superpower
By the early 1960s, the bomber force was being cut back as the incoming Kennedy administration invested in what it saw as the more cost-effective option of ICBMs. An indicator of changing priorities was the scrapping of the North American XB-70 Valkyrie supersonic bomber. This futuristic, delta-winged plane, designed to fly at a speed of Mach 3, was considered too expensive and also unduly vulnerable to newly introduced surface-to-air missiles.
Nonetheless the USAF retained a formidable fighter and bomber force, supported by a range of aircraft developed for different purposes. Before the advent of space satellites, the high-altitude Lockheed U-2 – supplemented from 1966 by the SR-71 Blackbird, the world’s fastest jet – was used for covert surveillance flights. A succession of transport planes with increasing capacity – the Douglas C-124 Globemaster and the Lockheed C-130 Hercules and C-5 Galaxy – enabled the US to carry out global airlift operations. Despite the challenges of a constantly changing environment, the USAF retained immense capacity to project American power across the globe.
Graham Goodlad has taught history and politics for more than 30 years. He is a freelance writer and a frequent contributor to MHM.
• One of the best ways for British readers to learn about US airpower is to visit the American Air Museum at the Imperial War Museum, Duxford, Cambridgeshire, CB22 4QR (see http://www.iwm.org.uk/visits/iwm-duxford/american-air-museum).
• The 1955 feature film Strategic Air Command, starring James Stewart (himself a former B-24 pilot, as well as a leading Hollywood actor), is worth watching for its spectacular aerial footage of B-36 and B-47 bombers.
All images: Wikimedia Commons, unless otherwise stated
