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51-454: In 1940, the U.S. Army Air Corps issued Request for Proposal R-40C, requesting designs for a high-speed, long-range, high-altitude interceptor intended to destroy enemy bombers . The specifications were very bold, encouraging manufacturers to produce radical aircraft that would outperform any existing fighter in the world at the time. The aerospace parts manufacturer McDonnell Aircraft , eager to begin manufacturing its own aircraft, responded to

102-402: A 75 mm (2.95 in) cannon before the configuration of six 37 mm (1.46 in) M4 cannon was chosen. Power would be provided by two Continental XI-1430-1 inverted V-12 engines, fitted with turbosuperchargers , and the engine exhaust gases would augment thrust. An extensive aerodynamic test program of the numerous advanced aspects of the design was begun by McDonnell, NACA , and

153-592: A larger and more streamlined form of airship designed by German Count Ferdinand von Zeppelin , were outfitted to carry bombs to attack targets at long range. These were the first long range, strategic bombers. Although the German air arm was strong, with a total of 123 airships by the end of the war, they were vulnerable to attack and engine failure, as well as navigational issues. German airships inflicted little damage on all 51 raids, with 557 Britons killed and 1,358 injured. The German Navy lost 53 of its 73 airships, and

204-483: A major limitation, combined with the desire for accuracy and other operational factors, bomber designs tended to be tailored to specific roles. By the start of the war this included: Bombers of this era were not intended to attack other aircraft although most were fitted with defensive weapons. World War II saw the beginning of the widespread use of high speed bombers which began to minimize defensive weaponry in order to attain higher speed. Some smaller designs were used as

255-538: A means of evading detection and attack. Designs such as the English Electric Canberra could fly faster or higher than contemporary fighters. When surface-to-air missiles became capable of hitting high-flying bombers, bombers were flown at low altitudes to evade radar detection and interception. Once "stand off" nuclear weapon designs were developed, bombers did not need to pass over the target to make an attack; they could fire and turn away to escape

306-431: A radome. The primary design issue with aircraft-mounted nacelles is streamlining to minimise drag so nacelles are mounted on slender pylons. This can cause issues with directing the needed conduits mounted within the nacelle to connect to the aircraft through such a narrow space. This is especially concerning with nacelles containing engines, as the fuel, and control, lines for multiple engine functions must all go through

357-421: A word for a small boat. The Arado Ar 234 was one of the first operational jet aircraft with engines mounted in nacelles. During its development, the four engines had four distinct nacelles. They once had their own landing gear wheel, but they were later combined to two nacelles with two engines each. Around 2010, General Electric and NASA have developed nacelles with chevron-shaped trailing edges to reduce

408-433: Is done by heavy bombers primarily designed for long-range bombing missions against strategic targets to diminish the enemy's ability to wage war by limiting access to resources through crippling infrastructure, reducing industrial output, or inflicting massive civilian casualties to an extent deemed to force surrender. Tactical bombing is aimed at countering enemy military activity and in supporting offensive operations, and

459-492: Is typically assigned to smaller aircraft operating at shorter ranges, typically near the troops on the ground or against enemy shipping. During WWII with engine power as a major limitation, combined with the desire for accuracy and other operational factors, bomber designs tended to be tailored to specific roles. Early in the Cold War however, bombers were the only means of carrying nuclear weapons to enemy targets, and held

510-488: Is typically assigned to smaller aircraft operating at shorter ranges, typically near the troops on the ground or against enemy shipping. This role is filled by tactical bomber class, which crosses and blurs with various other aircraft categories: light bombers , medium bombers , dive bombers , interdictors , fighter-bombers , attack aircraft , multirole combat aircraft , and others. The first use of an air-dropped bomb (actually four hand grenades specially manufactured by

561-799: The Bristol Aeroplane Company . They were fitted with a prismatic Bombsight in the front cockpit and a cylindrical bomb carrier in the lower forward fuselage capable of carrying twelve 10 lb (4.5 kg) bombs, which could be dropped singly or as a salvo as required. The aircraft was purchased for use both by the Royal Naval Air Service and the Royal Flying Corps (RFC), and three T.B.8s, that were being displayed in Paris during December 1913 fitted with bombing equipment, were sent to France following

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612-551: The Handley Page Type O ; the majority of bombing was done by single-engined biplanes with one or two crew members flying short distances to attack enemy lines and immediate hinterland. As the effectiveness of a bomber was dependent on the weight and accuracy of its bomb load, ever larger bombers were developed starting in World War I, while considerable money was spent developing suitable bombsights. With engine power as

663-649: The Italo-Turkish War , with the first major deployments coming in the First World War and Second World War by all major airforces, damaging cities, towns, and rural areas. The first bomber planes in history were the Italian Caproni Ca 30 and British Bristol T.B.8 , both of 1913. Some bombers were decorated with nose art or victory markings . There are two major classifications of bomber: strategic and tactical. Strategic bombing

714-461: The Model 2 , which was also rejected, so it was reworked into the Model 2A , which emerged on 24 April 1941. The new design was powered by a more traditional layout, a pair of engines in wing-mounted nacelles with four-bladed propellers in a tractor configuration . However, the design was still quite ambitious; the design team tried to maintain a true airfoil section through the center fuselage, merge

765-490: The North American P-51 Mustang . Upon return to the factory, the cooling ducts were reworked. Several problems were cured during the ensuing test flights, but the engines continued to be plagued by chronic overheating and deficient power output. The XP-67 only reached a confirmed top speed of 405 mph (652 km/h), which was far short of its promised top speed of 472 mph (760 km/h), and

816-505: The Swedish Air Force dropped bombs on a forest fire, snuffing out flames with the aid of the blast waves. The fires had been raging in an area contaminated with unexploded ordnance , rendering them difficult to extinguish for firefighters. Nacelle A nacelle ( / n ə ˈ s ɛ l / nə- SEL ) is a streamlined container for aircraft parts such as engines , fuel or equipment. When attached entirely outside

867-641: The Turkish railway station of Karağaç (near the besieged Edirne ) from an Albatros F.2 aircraft piloted by Radul Milkov , during the First Balkan War . This is deemed to be the first use of an aircraft as a bomber. The first heavier-than-air aircraft purposely designed for bombing were the Italian Caproni Ca 30 and British Bristol T.B.8 , both of 1913. The Bristol T.B.8 was an early British single engined biplane built by

918-601: The University of Detroit . The design demanded skin that was perfectly smooth and precisely shaped to maintain its laminar-flow characteristics, mandating the development of new construction techniques, as the company had never produced an entire aircraft before. Wind tunnel testing uncovered problems with engine cooling airflow through the engine nacelles, which were never fully resolved. Difficulties were also encountered in obtaining engines, as wartime production demands hampered Continental's efforts to deliver running examples of

969-966: The V bomber force was phased out; the last of which left service in 1983. The French Mirage IV bomber version was retired in 1996, although the Mirage 2000N and the Rafale have taken on this role. The only other nation that fields strategic bombing forces is China , which has a number of Xian H-6s . Currently, only the United States Air Force , the Russian Aerospace Forces ' Long-Range Aviation command, and China's People's Liberation Army Air Force operate strategic heavy bombers. Other air forces have transitioned away from dedicated bombers in favor of multirole combat aircraft . At present, these air forces are each developing stealth replacements for their legacy bomber fleets,

1020-509: The 1950s-designed B-52s are projected to remain in use until the 2040s. Similarly, the Soviet Union used the intermediate-range Tu-22M 'Backfire' in the 1970s, but their Mach 3 bomber project stalled. The Mach 2 Tu-160 'Blackjack' was built only in tiny numbers, leaving the 1950s Tupolev Tu-16 and Tu-95 'Bear' heavy bombers to continue being used into the 21st century. The British strategic bombing force largely came to an end when

1071-629: The Allied Armies." When the war started, bombing was very crude (hand-held bombs were thrown over the side) yet by the end of the war long-range bombers equipped with complex mechanical bombing computers were being built, designed to carry large loads to destroy enemy industrial targets. The most important bombers used in World War I were the French Breguet 14 , British de Havilland DH-4 , German Albatros C.III and Russian Sikorsky Ilya Muromets . The Russian Sikorsky Ilya Muromets ,

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1122-604: The German Army lost 26 of its 50 ships. The Caproni Ca 30 was built by Gianni Caproni in Italy . It was a twin-boom biplane with three 67 kW (80 hp) Gnome rotary engines and first flew in October 1914 . Test flights revealed power to be insufficient and the engine layout unworkable, and Caproni soon adopted a more conventional approach installing three 81 kW (110 hp) Fiat A.10s . The improved design

1173-653: The Italian naval arsenal) was carried out by Italian Second Lieutenant Giulio Gavotti on 1 November 1911 during the Italo-Turkish war in Libya – although his plane was not designed for the task of bombing, and his improvised attacks on Ottoman positions had little impact. These picric acid -filled steel spheres were nicknamed "ballerinas" from the fluttering fabric ribbons attached. On 16 October 1912, Bulgarian observer Prodan Tarakchiev dropped two of those bombs on

1224-828: The USAF with the Northrop Grumman B-21 , the Russian Aerospace Forces with the PAK DA , and the PLAAF with the Xian H-20 . As of 2021 , the B-21 is expected to enter service by 2026–2027. The B-21 would be capable of loitering near target areas for extended periods of time. Occasionally, military aircraft have been used to bomb ice jams with limited success as part of an effort to clear them. In 2018,

1275-613: The War as the German air arm was forced to concentrate its resources on a defensive strategy. Notably, bombing campaigns formed a part of the British offensive at the Battle of Neuve Chapelle in 1915, with Royal Flying Corps squadrons attacking German railway stations in an attempt to hinder the logistical supply of the German army . The early, improvised attempts at bombing that characterized

1326-574: The XP-67 so the flames blew directly towards the aft fuselage. Elliot escaped safely, but the blaze gutted the fuselage, engine, nacelle, and starboard wing; the aircraft was a total loss. The destruction of the lone flying prototype dealt a serious blow to the entire program because the second prototype was only 15% complete at the time. Army leaders decided to reevaluate the XP-67, ultimately deciding on 13 September that it offered no significant advantages over existing fighters already in service. The project

1377-508: The XP-67 waited for replacement engines. On 23 March 1944, flight trials restarted. U.S. Army Air Forces pilots finally got to fly the aircraft on 11 May 1944, and judged the cockpit layout fair and ground handling satisfactory, but deemed the aircraft underpowered due to its poor initial rate of climb, slow acceleration, and long takeoff roll, particularly when operating with only one engine. Other flight characteristics were generally good during gentle maneuvers; stick forces were light, roll rate

1428-414: The XP-67's spin characteristics, fearing that a spin might be unrecoverable. This irregular and unstable stall behavior has been attributed to advanced aerodynamic principles that were not fully counteracted until the advent of electronic stability controls years later. Although the final flight test report was generally positive, the aircraft's maneuverability was deemed inferior to existing types such as

1479-498: The airframe, it is sometimes called a pod, in which case it is attached with a pylon or strut and the engine is known as a podded engine . In some cases—for instance in the typical " Farman " type "pusher" aircraft , or the World War II -era P-38 Lightning —an aircraft cockpit may also be housed in a nacelle, rather than in a conventional fuselage . Like many aviation terms, the word comes from French , in this case from

1530-633: The basis for night fighters . A number of fighters, such as the Hawker Hurricane were used as ground attack aircraft, replacing earlier conventional light bombers that proved unable to defend themselves while carrying a useful bomb load. At the start of the Cold War, bombers were the only means of carrying nuclear weapons to enemy targets, and had the role of deterrence . With the advent of guided air-to-air missiles, bombers needed to avoid interception. High-speed and high-altitude flying became

1581-495: The blast. Nuclear strike aircraft were generally finished in bare metal or anti-flash white to minimize absorption of thermal radiation from the flash of a nuclear explosion . The need to drop conventional bombs remained in conflicts with non-nuclear powers, such as the Vietnam War or Malayan Emergency . The development of large strategic bombers stagnated in the later part of the Cold War because of spiraling costs and

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1632-555: The case of larger aircraft such as the Boeing B-52 Stratofortress (pictured right) may have two engines mounted in a single nacelle. Nacelles can be made fully or partially detachable for holding expendable resources such as fuel and armaments. Nacelles may be used to house equipment that will only function remote from the fuselage, for example the Boeing E-3 Sentry radar is housed in a nacelle called

1683-588: The development of the Intercontinental ballistic missile (ICBM) – which was felt to have similar deterrent value while being impossible to intercept. Because of this, the United States Air Force XB-70 Valkyrie program was cancelled in the early 1960s; the later B-1B Lancer and B-2 Spirit aircraft entered service only after protracted political and development problems. Their high cost meant that few were built and

1734-474: The early part of the war slowly gave way to a more organized and systematic approach to strategic and tactical bombing, pioneered by various air power strategists of the Entente , especially Major Hugh Trenchard ; he was the first to advocate that there should be "... sustained [strategic bombing] attacks with a view to interrupting the enemy's railway communications ... in conjunction with the main operations of

1785-647: The enemy's ability to wage war by limiting access to resources through crippling infrastructure or reducing industrial output. Current examples include the strategic nuclear-armed bombers: B-2 Spirit , B-52 Stratofortress , Tupolev Tu-95 'Bear' , Tupolev Tu-22M 'Backfire' and Tupolev Tu-160 "Blackjack" ; historically notable examples are the: Gotha G.IV , Avro Lancaster , Heinkel He 111 , Junkers Ju 88 , Boeing B-17 Flying Fortress , Consolidated B-24 Liberator , Boeing B-29 Superfortress , and Tupolev Tu-16 'Badger'. Tactical bombing , aimed at countering enemy military activity and in supporting offensive operations,

1836-507: The engine bearings burned out when the engines were accidentally overspeeded. By this time, it was becoming obvious that the XP-67 was hampered by a serious lack of power. The engines were only delivering 1,060 hp (790 kW), well short of their promised 1,350 hp (1,007 kW) rating. Company founder Jim McDonnell , frustrated by engine procurement delays and the XI-1430's subpar output, began to campaign for funding to re-engine

1887-579: The engine noise of commercial aircraft, using an experimental Boeing 777 as a test platform. Usually, multi-engined aircraft use nacelles for housing the engines. Combat aircraft (such as the Eurofighter Typhoon ) usually have the engines mounted within the fuselage. Some engines are installed in the aircraft wing, as in the De Havilland Comet and Flying Wing type aircraft. Engines may be mounted in individual nacelles, or in

1938-523: The experimental XI-1430 engines to competing aircraft test programs. The project was also delayed by intense competition for testing time at the NACA wind tunnel facility in Langley, Virginia . The first XP-67, 42-11677 , was ready for ground trials on 1 December 1943. The aircraft was fitted with XI-1430-17/19 engines and General Electric D-23 turbo-superchargers but no pressurization equipment or armament

1989-421: The outbreak of war. Under the command of Charles Rumney Samson , a bombing attack on German gun batteries at Middelkerke , Belgium was executed on 25 November 1914. The dirigible, or airship, was developed in the early 20th century. Early airships were prone to disaster, but slowly the airship became more dependable, with a more rigid structure and stronger skin. Prior to the outbreak of war, Zeppelins ,

2040-542: The proposal with drawings and specifications of the proposed Model 1 , which would be powered by an unusual geared drivetrain with a single Allison V-3420 engine buried in the fuselage powering twin wing-mounted pusher propellers in the wings. However, 22 other manufacturers also issued proposals to meet the Army's request; the McDonnell proposal had relatively unimpressive anticipated performance, and its odd drivetrain

2091-424: The prototype with a pair of Allison or Rolls-Royce piston engines augmented by auxiliary Westinghouse turbojets in the aft nacelles. Although McDonnell promised a very impressive 500 mph (805 km/h) top speed with the new powerplants, the Army rejected the proposal, demanding more testing of the existing design. As a result of wind tunnel tests, the tailplanes were raised 12 in (31 cm) while

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2142-410: The rear portions of the engine nacelles with the wing, and radically fillet all edges of the fuselage and nacelles into the wings in an effort to reduce drag. The design used laminar airfoil sections throughout. McDonnell designers promised that the design would deliver a top speed of 472 mph (760 km/h) with a gross weight of 18,600 lb (8,440 kg), although the anticipated gross weight

2193-585: The role of deterrence . With the advent of guided air-to-air missiles, bombers needed to avoid interception. High-speed and high-altitude flying became a means of evading detection and attack. With the advent of ICBMs the role of the bomber was brought to a more tactical focus in close air support roles, and a focus on stealth technology for strategic bombers. Strategic bombing is done by heavy bombers primarily designed for long-range bombing missions against strategic targets such as supply bases, bridges, factories, shipyards, and cities themselves, to diminish

2244-440: Was adequate, and control was effective at all speeds with good longitudinal stability. However, a tendency to dutch roll was prevalent. The prototype also displayed several disturbing behaviors as its stall speed was approached. It began to buffet well above the actual stall speed, it felt tail-heavy in fast turns, and its nose would tuck upwards during the stall. The problems were serious enough that test pilots declined to test

2295-467: Was bought by the Italian Army and it was delivered in quantity from August 1915 . While mainly used as a trainer , Avro 504s were also briefly used as bombers at the start of the First World War by the Royal Naval Air Service (RNAS) when they were used for raids on the German airship sheds. Bombing raids and interdiction operations were mainly carried out by French and British forces during

2346-523: Was canceled, the remains of the first prototype scrapped, and work halted on the second prototype. Data from McDonnell Douglas Aircraft since 1920 General characteristics Performance Armament Aircraft of comparable role, configuration, and era Related lists Bomber A bomber is a military combat aircraft that utilizes air-to-ground weaponry to drop bombs , launch torpedoes , or deploy air-launched cruise missiles . Bombs were first dropped from an aircraft during

2397-399: Was installed. On 8 December, the aircraft was damaged by fires in both engine nacelles , caused by a malfunction of the exhaust manifold slip rings. By 6 January 1944, the damage was repaired and the XP-67 made its first flight, which ended after six minutes due to engine trouble. After modifications were made to the engine installations, two test flights were carried out. On the fourth flight,

2448-651: Was soon increased to a somewhat more realistic 20,000 lb (9,070 kg). On 30 September 1941, the USAAF granted McDonnell a $ 1,508,596 contract, plus an $ 86,315 fee, for two prototypes, a wind tunnel model, and associated engineering data. The Model 2A was designated as the XP-67 . The production aircraft was intended to have a pressurized cockpit , an innovation at the time. A number of armament configurations were considered including six .50 in (12.7 mm) machine guns , four 20 mm (.79 in) cannon, and even

2499-525: Was the first four-engine bomber to equip a dedicated strategic bombing unit during World War I . This heavy bomber was unrivaled in the early stages of the war, as the Central Powers had no comparable aircraft until much later. Long range bombing raids were carried out at night by multi-engine biplanes such as the Gotha G.IV (whose name was synonymous with all multi-engine German bombers) and later

2550-407: Was unproven. The Model 1 fell in 21st place when the 23 proposals were examined and scored. The proposals that were accepted included the similarly ill-fated XP-54 , XP-55 , and XP-56 . Despite the apparent setback, Air Corps leaders were impressed by the nascent company's efforts, and granted McDonnell a $ 3,000 contract to re-engineer the aircraft. McDonnell engineers returned on 30 June 1940 with

2601-470: Was unremarkable compared to other fighters in service at the time. On 6 September 1944, the starboard engine of the XP-67 caught fire during a test flight, and test pilot E.E. Elliot executed an emergency landing at Lambert Field in St. Louis, Missouri . He attempted to park the craft pointing into the wind to blow the flames away from the airframe, but the starboard main landing gear brakes failed, pivoting

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