Fighter aircraft
A fighter aircraft is a military aircraft designed for air-to-air combat against other aircraft, as opposed to bombers and attack aircraft, whose main mission is to attack ground targets. The hallmarks of a fighter are its speed and small size relative to other combat aircraft. Many fighters have secondary ground-attack capabilities, some are designed as dual-purpose fighter-bombers; this may be for national security reasons, for advertising purposes, or other reasons. A fighter's main purpose is to establish air superiority over a battlefield. Since World War I, achieving and maintaining air superiority has been considered essential for victory in conventional warfare; the success or failure of a belligerent's efforts to gain air superiority hinges on several factors including the skill of its pilots, the tactical soundness of its doctrine for deploying its fighters, the numbers and performance of those fighters. Because of the importance of air superiority, since the early days of aerial combat armed forces have competed to develop technologically superior fighters and to deploy these fighters in greater numbers, fielding a viable fighter fleet consumes a substantial proportion of the defense budgets of modern armed forces.
The word "fighter" did not become the official English-language term for such aircraft until after World War I. In the British Royal Flying Corps and Royal Air Force these aircraft were referred to as "scouts" into the early 1920s; the U. S. Army called their fighters "pursuit" aircraft from 1916 until the late 1940s. In most languages a fighter aircraft is known as hunting aircraft. Exceptions include Russian, where a fighter is an "истребитель", meaning "exterminator", Hebrew where it is "matose krav"; as a part of military nomenclature, a letter is assigned to various types of aircraft to indicate their use, along with a number to indicate the specific aircraft. The letters used to designate a fighter differ in various countries – in the English-speaking world, "F" is now used to indicate a fighter, though when the pursuit designation was used in the US, they were "P" types. In Russia "I" was used, while the French continue to use "C". Although the term "fighter" specifies aircraft designed to shoot down other aircraft, such designs are also useful as multirole fighter-bombers, strike fighters, sometimes lighter, fighter-sized tactical ground-attack aircraft.
This has always been the case, for instance the Sopwith Camel and other "fighting scouts" of World War I performed a great deal of ground-attack work. In World War II, the USAAF and RAF favored fighters over dedicated light bombers or dive bombers, types such as the Republic P-47 Thunderbolt and Hawker Hurricane that were no longer competitive as aerial combat fighters were relegated to ground attack. Several aircraft, such as the F-111 and F-117, have received fighter designations though they had no fighter capability due to political or other reasons; the F-111B variant was intended for a fighter role with the U. S. Navy, but it was cancelled; this blurring follows the use of fighters from their earliest days for "attack" or "strike" operations against ground targets by means of strafing or dropping small bombs and incendiaries. Versatile multirole fighter-bombers such as the McDonnell Douglas F/A-18 Hornet are a less expensive option than having a range of specialized aircraft types; some of the most expensive fighters such as the US Grumman F-14 Tomcat, McDonnell Douglas F-15 Eagle, Lockheed Martin F-22 Raptor and Russian Sukhoi Su-27 were employed as all-weather interceptors as well as air superiority fighter aircraft, while developing air-to-ground roles late in their careers.
An interceptor is an aircraft intended to target bombers and so trades maneuverability for climb rate. Fighters were developed in World War I to deny enemy aircraft and dirigibles the ability to gather information by reconnaissance over the battlefield. Early fighters were small and armed by standards, most were biplanes built with a wooden frame covered with fabric, a maximum airspeed of about 100 mph; as control of the airspace over armies became important, all of the major powers developed fighters to support their military operations. Between the wars, wood was replaced in part or whole by metal tubing, aluminium stressed skin structures began to predominate. On 15 August 1914, Miodrag Tomić encountered an enemy plane while conducting a reconnaissance flight over Austria-Hungary; the Austro-Hungarian aviator waved at Tomić, who waved back. The enemy pilot took a revolver and began shooting at Tomić's plane. Tomić fired back, he swerved away from the Austro-Hungarian plane and the two aircraft parted ways.
It was considered the first exchange of fire between aircraft in history. Within weeks, all Serbian and Austro-Hungarian aircraft were armed; the Serbians equipped their planes with 8-millimetre Schwarzlose MG M.07/12 machine guns, six 100-round boxes of ammunition and several bombs. By World War II, most fighters were all-metal monoplanes armed with batteries of machine guns or cannons and some were capable of speeds approaching 400 mph. Most fighters up to this point had one engine.
Stressed skin
In mechanical engineering, stressed skin is a type of rigid construction, intermediate between monocoque and a rigid frame with a non-loaded covering. A stressed skin structure has its compression-taking elements localized and its tension-taking elements distributed; the main frame has rectangular structure and is triangulated by the covering. A framework box can be distorted from being square, so it isn't rigid by itself, however adding diagonals that take either tension or compression fixes this, because the box cannot deviate from right angles without altering the diagonals. Sometimes flexible members like wires are used to provide tension, or rigid compression frames are used, as with a Warren or Pratt truss, however both these are full frame structures; when the skin or outer covering is in tension so that it provides a significant portion of the rigidity, the structure is said to have a stressed skin design. This may be referred to as semi-monocoque, overlaps with monocoque, which has less framing, sometimes only including longitudinal or lateral members and overlaps with rigid frame structures where a minor portion of the overall stiffness may be derived from the skin.
This method of construction is lighter than a full frame structure and not as complex to design as a full monocoque. Examples include nearly all modern all-metal airplanes, as well as some railway vehicles and motorhomes; the London Transport AEC Routemaster incorporated internal panels riveted to the frames which took most of the structure's shear load. Automobile unibodies are a form a stressed skin as well, as are some framed buildings which lack diagonal bracing. Dornier-Zeppelin D. I: first all-metal stressed skin fighter and first with stressed skin wings Short Silver Streak: first all-metal British stressed skin aircraft Zeppelin-Lindau Rs. IV: first aircraft with an all-metal stressed skin fuselage to fly Zeppelin-Staaken E-4/20: first all-metal stressed skin four-engine airliner Northrop Alpha: first American all-metal stressed skin aircraft GM New Look bus: stressed skin bus, over 44,000 built since 1959, many still in service. Stressed Skin Wood to Metal: The Structural Origins of the Modern Airplane
Prototype
A prototype is an early sample, model, or release of a product built to test a concept or process or to act as a thing to be replicated or learned from. It is a term used in a variety of contexts, including semantics, design and software programming. A prototype is used to evaluate a new design to enhance precision by system analysts and users. Prototyping serves to provide specifications for a real, working system rather than a theoretical one. In some design workflow models, creating a prototype is the step between the formalization and the evaluation of an idea; the word prototype derives from the Greek πρωτότυπον prototypon, "primitive form", neutral of πρωτότυπος prototypos, "original, primitive", from πρῶτος protos, "first" and τύπος typos, "impression". Prototypes explore different aspects of an intended design: A Proof-of-Principle Prototype serves to verify some key functional aspects of the intended design, but does not have all the functionality of the final product. A Working Prototype represents all or nearly all of the functionality of the final product.
A Visual Prototype represents the size and appearance, but not the functionality, of the intended design. A Form Study Prototype is a preliminary type of visual prototype in which the geometric features of a design are emphasized, with less concern for color, texture, or other aspects of the final appearance. A User Experience Prototype represents enough of the appearance and function of the product that it can be used for user research. A Functional Prototype captures both function and appearance of the intended design, though it may be created with different techniques and different scale from final design. A Paper Prototype is a printed or hand-drawn representation of the user interface of a software product; such prototypes are used for early testing of a software design, can be part of a software walkthrough to confirm design decisions before more costly levels of design effort are expended. In general, the creation of prototypes will differ from creation of the final product in some fundamental ways: Material: The materials that will be used in a final product may be expensive or difficult to fabricate, so prototypes may be made from different materials than the final product.
In some cases, the final production materials may still be undergoing development themselves and not yet available for use in a prototype. Process: Mass-production processes are unsuitable for making a small number of parts, so prototypes may be made using different fabrication processes than the final product. For example, a final product that will be made by plastic injection molding will require expensive custom tooling, so a prototype for this product may be fabricated by machining or stereolithography instead. Differences in fabrication process may lead to differences in the appearance of the prototype as compared to the final product. Verification: The final product may be subject to a number of quality assurance tests to verify conformance with drawings or specifications; these tests may involve custom inspection fixtures, statistical sampling methods, other techniques appropriate for ongoing production of a large quantity of the final product. Prototypes are made with much closer individual inspection and the assumption that some adjustment or rework will be part of the fabrication process.
Prototypes may be exempted from some requirements that will apply to the final product. Engineers and prototype specialists attempt to minimize the impact of these differences on the intended role for the prototype. For example, if a visual prototype is not able to use the same materials as the final product, they will attempt to substitute materials with properties that simulate the intended final materials. Engineers and prototyping specialists seek to understand the limitations of prototypes to simulate the characteristics of their intended design, it is important to realize that by their definition, prototypes will represent some compromise from the final production design. Due to differences in materials and design fidelity, it is possible that a prototype may fail to perform acceptably whereas the production design may have been sound. A counter-intuitive idea is that prototypes may perform acceptably whereas the production design may be flawed since prototyping materials and processes may outperform their production counterparts.
In general, it can be expected that individual prototype costs will be greater than the final production costs due to inefficiencies in materials and processes. Prototypes are used to revise the design for the purposes of reducing costs through optimization and refinement, it is possible to use prototype testing to reduce the risk that a design may not perform as intended, however prototypes cannot eliminate all risk. There are pragmatic and practical limitations to the ability of a prototype to match the intended final performance of the product and some allowances and engineering judgement are required before moving forward with a production design. Building the full design is expensive and can be time-consuming when repeated several times—building the full design, figuring out what the problems are and how to solve them building another full design; as an alternative, rapid prototyping or rapid application development techniques are used for the initial prototypes, which implement part, but not all, of the complete design.
This allows designers and manufacturers to and inexpensively test the parts of the design that are most to have problems, solve those problems, build the full design. This counter-intuitive idea—that the quickest way to build something is, f
Flap (aeronautics)
Flaps are a kind of high-lift device used to increase the lift of an aircraft wing at a given airspeed. Flaps are mounted on the wing trailing edges of a fixed-wing aircraft. Flaps are used for extra lift on takeoff. Flaps cause an increase in drag in mid-flight, so they are retracted when not needed. Extending the wing flaps increases the camber or curvature of the wing, raising the maximum lift coefficient or the upper limit to the lift a wing can generate; this allows the aircraft to generate the required lift at a lower speed, reducing the stalling speed of the aircraft, therefore the minimum speed at which the aircraft will safely maintain flight. The increase in camber increases the wing drag, which can be beneficial during approach and landing, because it slows the aircraft. In some aircraft configurations, a useful side effect of flap deployment is a decrease in aircraft pitch angle, which lowers the nose thereby improving the pilot's view of the runway over the nose of the aircraft during landing.
In other configurations, depending on the type of flap and the location of the wing, flaps can cause the nose to rise, obscuring the pilot's view of the runway. There are many different designs of flaps used, with the specific choice depending on the size and complexity of the aircraft on which they are to be used, as well as the era in which the aircraft was designed. Plain flaps, slotted flaps, Fowler flaps are the most common. Krueger flaps are used on many jet airliners; the Fowler, Fairey-Youngman and Gouge types of flap increase the wing area in addition to changing the camber. The larger lifting surface reduces wing loading, hence further reducing the stalling speed; some flaps are fitted elsewhere. Leading-edge flaps form the wing leading edge and when deployed they rotate down to increase the wing camber; the de Havilland DH.88 Comet racer had flaps running beneath the fuselage and forward of the wing trailing edge. Many of the Waco Custom Cabin series biplanes have the flaps at mid-chord on the underside of the top wing.
The general airplane lift equation demonstrates these relationships: L = 1 2 ρ V 2 S C L where: L is the amount of Lift produced, ρ is the air density, V is the true airspeed of the airplane or the Velocity of the airplane, relative to the air S is the area of the wing C L is the lift coefficient, determined by the shape of the airfoil used and the angle at which the wing meets the air. Here, it can be seen that increasing the area and lift coefficient allow a similar amount of lift to be generated at a lower airspeed. Extending the flaps increases the drag coefficient of the aircraft. Therefore, for any given weight and airspeed, flaps increase the drag force. Flaps increase the drag coefficient of an aircraft due to higher induced drag caused by the distorted spanwise lift distribution on the wing with flaps extended; some flaps increase the wing area and, for any given speed, this increases the parasitic drag component of total drag. Depending on the aircraft type, flaps may be extended for takeoff.
When used during takeoff, flaps trade runway distance for climb rate: using flaps reduces ground roll but reduces the climb rate. The amount of flap used on takeoff is specific to each type of aircraft, the manufacturer will suggest limits and may indicate the reduction in climb rate to be expected; the Cessna 172S Pilot Operating Handbook recommends 10° of flaps on takeoff when the ground is rough or soft. Flaps may be extended for landing to give the aircraft a lower stall speed so the approach to landing can be flown more which allows the aircraft to land in a shorter distance; the higher lift and drag associated with extended flaps allows a steeper and slower approach to the landing site, but imposes handling difficulties in aircraft with low wing loading. Winds across the line of flight, known as crosswinds, cause the windward side of the aircraft to generate more lift and drag, causing the aircraft to roll and pitch off its intended flight path, as a result many light aircraft land with reduced flap settings in crosswinds.
Furthermore, once the aircraft is on the ground, the flaps may decrease the effectiveness of the brakes since the wing is still generating lift and preventing the entire weight of the aircraft from resting on the tires, thus increasing stopping distance in wet or icy conditions. The pilot will raise the flaps as soon as possible to prevent this from occurring; some gliders not only use flaps when landing, but in flight to optimize the camber of the wing for the chosen speed. While thermalling, flaps may be extended to reduce the stall speed so that the glider can be flown more and thereby reduce the rate of sink, which lets the glider use the rising air of the thermal more efficiently, to turn in a smaller circle to make best use of the core of the thermal. At higher speeds a negative flap setting is used to reduce the nose-down pitching moment; this reduces the balancing load required on the horizontal stabilizer, which in turn reduces the trim drag associated with keeping the glider in longitudinal trim.
Negative flap may be used during the initial stage of an aerotow launch and at the end of the landing run in order to maintain better control by the ailerons. Like gliders, some fighters such as the
LATAM Chile
LATAM Airlines LAN Airlines S. A. and Lan Chile, is an airline based in Santiago, is one of the founders of LATAM Airlines Group, Latin America's largest airline holding company. The main hub is Comodoro Arturo Merino Benítez International Airport, with secondary hubs in El Dorado, Jorge Chávez, José Joaquín de Olmedo, Jorge Newbery and Mariscal Sucre airports. LAN Airlines was the flag carrier of Chile until its privatization in the 1990s, is the predominant airline in Chile and Peru, the second largest carrier in Argentina and Ecuador, through its local subsidiaries. LAN is the largest airline in Latin America, serving Latin America, North America, the Caribbean and Europe; the carrier has been a member of the Oneworld airline alliance since 2000. LATAM Airlines Group was formed after the takeover by LAN of Brazilian TAM Airlines, completed on June 22, 2012. In August 2015, it was announced that the two airlines would rebrand as LATAM, with one livery to be applied on all aircraft by 2018. LAN and TAM continue to work as separate companies, under a common executive management.
LATAM Airlines Group is the largest airline conglomerate in Latin America. The airline was founded by Chilean Air Force Commodore Arturo Merino Benítez, began operations on March 5, 1929 as Línea Aeropostal Santiago-Arica, under the government of President Carlos Ibáñez del Campo. In 1932 It was rebranded as Línea Aérea Nacional de Chile, using the acronym LAN-Chile as its commercial name. LAN-Chile's first fleet consisted of de Havilland Moth planes. Merino Benitez was a strong defender of Chilean carriers exclusivity on domestic routes, differing from most Latin American countries which granted authorization on domestic flights to US-based Panagra, influenced by the propaganda made by Charles Lindbergh's Atlantic crossing; because of this reason, US-built airplanes became more difficult to incorporate to LAN's fleet until the beginning of WWII. In 1936, 2 French Potez 560 airplanes were purchased while in 1938, 4 German Junkers Ju 86Bs were incorporated to the fleet. During that same year, a joint cooperation agreement was established with Lloyd Aéreo Boliviano and the Peruvian carrier Faucett.
Another agreement with Lufthansa was signed for flights to & from Europe and America's Atlantic coast. In 1940, given the restrictions imposed during WWII on access to spare parts for the Junker's BMW engines, LAN-Chile had to replace them for Lockheed Electra 10-A planes, adding in 1941 further Lockheed Lodestar C-60 and Douglas DC-3 in 1945. On August 23, 1945, LAN-Chile became a member of the newly formed IATA. In October 1946, it started international service to Buenos Aires at Morón Airport and in 1947 to Punta Arenas, Chile's most distant continental destination. In December 1954, LAN-Chile made its first commercial flight to Lima, Perú. On December 22, 1956 a LAN-Chile Douglas DC-6 made the world's first commercial flight over Antarctica. Since all LAN's DC-6 fleet had painted on their fuselage "Primeros sobre la Antártica", using this same aircraft type for its first commercial service to Miami International Airport in 1958. LAN-Chile entered the jet era in 1963, purchasing three French Sud Aviation Caravelle VI-R, which flew to Miami, Lima, Panama City and within Chile to Punta Arenas, Puerto Montt and Antofagasta.
In 1966, LAN-Chile purchased from Lufthansa its first Boeing 707, in exchange for flying rights in the Lima-Santiago route. With this aircraft model, the company developed new long haul routes to Oceania and Europe. LAN-Chile started on April 15, 1967, the route Santiago-John F. Kennedy International Airport and Santiago-Easter Island on April 8. In October 1967 a LAN-Chile Sud Aviation Caravelle made the first ILS landing in South America at Lima's Jorge Chávez International Airport. On January 16, 1968, the Santiago-Easter Island flight was extended to Papeete-Faa'a International Airport, in Tahiti, French Polynesia. On September 4, 1974, this route was extended to Fiji. In 1969, LAN-Chile expanded its destinations to Rio de Janeiro, Asunción and Cali with new Boeing 727s. In 1970, with Boeing 707s LAN-Chile opened its first transatlantic routes to Madrid–Barajas Airport, Frankfurt Airport and Paris-Orly. Since its inception and until 1970 the airline had its headquarters, main hub and maintenance center at Los Cerrillos Airport, in South-West Santiago.
The restrictions imposed by the growing metropolitan area of Santiago and the need for modern, jet-era airport facilities that could safely accommodate both domestic and intercontinental flights, drove the need to relocate the Chilean capital's principal airport from Los Cerrillos in the denser southwest metropolitan region of Santiago to the more rural northwest metropolitan area. For this reason, Santiago International Airport in Pudahuel was built between 1961 and 1967 moving LAN-Chile's flights to this new airport in 1970. On February 10, 1974, A LAN Chile Boeing 707 flown by captain Jorge Jarpa Reyes made the world's first transpolar non-stop flight between South America and Australia. In 1980, the company replaced its Boeing 727s with 737-200 Advanced on its domestic routes. In addition, the McDonnell Douglas DC-10-30, LAN Chile's first wide body jets, were added for use on routes to Los Angeles and New York; that same year, the maintenance facilitites were relocated from Los Cerrillos to Arturo Merino Benitez Airport.
In 1985, LAN-Chile implemented a program of flights around the world called Cruceros del Aire
East African Campaign (World War II)
The East African Campaign was fought in East Africa during World War II by Allied forces from the British Empire, against Axis forces from Italy of Italian East Africa, between June 1940 and November 1941. Forces of the British Middle East Command, including units from the United Kingdom and the colonies of British East Africa, British Somaliland, British West Africa, the Indian Empire, Northern Rhodesia, Mandatory Palestine, South Africa, Southern Rhodesia and Sudan participated in the campaign. Ethiopian irregulars, the Free French and the Belgian Force Publique participated; the AOI was defended by Italian forces of the Comando Forze Armate dell'Africa Orientale Italiana, with units from the Regio Esercito, Regia Aeronautica and Regia Marina, about 200,000 Regio Corpo Truppe Coloniali from Italian-occupied Abyssinia, Italian Eritrea and Italian Somaliland, led by Italian officers and NCOs, 70,000 Italian regulars and reservists. The Compagnia Autocarrata Tedesca fought under Italian command.
Hostilities began on 13 June 1940, with an Italian air raid on the base of 1 Squadron Southern Rhodesian Air Force at Wajir in the East Africa Protectorate and continued until Italian forces had been pushed back from Kenya and Sudan, through Somaliland and Ethiopia in 1940 and early 1941. The remnants of the Italian forces in the AOI surrendered after the Battle of Gondar in November 1941, except for small groups that fought a guerrilla war in Ethiopia against the British until the Armistice of Cassibile ended hostilities between Italy and the Allies; the East African Campaign was the first Allied strategic victory in the war. On 9 May 1936, the Italian dictator, Benito Mussolini, proclaimed the formation of Italian East Africa, from Ethiopia after the Second Italo-Abyssinian War and the colonies of Italian Eritrea and Italian Somaliland. On 10 June 1940, Mussolini declared war on Britain and France, which made Italian military forces in Libya a threat to Egypt and those in the AOI a danger to the British and French colonies in East Africa.
Italian belligerence closed the Mediterranean to Allied merchant ships and endangered British sea lanes along the coast of East Africa, the Gulf of Aden, the Red Sea and the Suez Canal. Egypt, the Suez Canal, French Somaliland and British Somaliland were vulnerable to invasion but Comando Supremo had planned for a war after 1942. Amedeo, Duke of Aosta, was appointed Viceroy and Governor-General of the AOI in November 1937, with a headquarters in Addis Ababa, the Ethiopian capital. On 1 June 1940, as the commander in chief of Comando Forze Armate dell'Africa Orientale Italiana and Generale d'Armata Aerea, Aosta had about 290,476 local and metropolitan troops. By 1 August, mobilisation had increased the number to 371,053 troops. On 10 June, the Italian army was organised in four commands: Northern Sector, vicinity of Asmara Eritrea, Lieutenant-General Luigi Frusci Southern Sector, around Jimma Ethiopia, General Pietro Gazzera Eastern Sector, General Guglielmo Nasi Giuba Sector, Lieutenant-General Carlo De Simone, southern Somalia near Kismayo, Italian Somaliland Aosta had two metropolitan divisions, the 40th Infantry Division Cacciatori d'Africa and the 65th Infantry Division Granatieri di Savoia, a battalion of Alpini, a Bersaglieri battalion of motorised infantry, several "Blackshirt" Milizia Coloniale battalions and smaller units.
About 70 percent of Italian troops were locally recruited Askari. The regular Eritrean battalions and the Regio Corpo Truppe Coloniali were among the best Italian units in the AOI and included Eritrean cavalry Penne di Falco. Most colonial troops were recruited and equipped for colonial repression, although the Somali Dubats from the borderlands were useful light infantry and skirmishers. Irregular bandes were hardy and mobile, knew the country and were effective scouts and saboteurs, although sometimes confused with Shifta, undisciplined marauders who plundered and murdered at will. Once Italy entered the war, a 100-strong company formed out of German residents of East Africa and German sailors unable to leave East African ports. Italian forces in East Africa were equipped with about 3,313 heavy machine-guns, 5,313 machine-guns, 24 M11/39 medium tanks, 39 L3/35 tankettes, 126 armoured cars and 824 guns, twenty-four 20 mm anti-aircraft guns, seventy-one 81 mm mortars and 672,800 rifles. Due to the isolation of the AOI from the Mediterranean, the Italians had little opportunity for reinforcements or supply, leading to severe shortages of ammunition.
On occasion, foreign merchant vessels captured by German merchant raiders in the Indian Ocean were brought to Somali ports but their cargoes were not always of much use to the Italian war effort. (For example, the Yugoslav steamer Durmitor, captured by the German auxiliary cruiser Atlantis, came to Warsheikh on 22 November 1940, with a cargo of salt and several hund
Heinkel He 111
The Heinkel He 111 was a German aircraft designed by Siegfried and Walter Günter at Heinkel Flugzeugwerke in 1934. Through development it was described as a "wolf in sheep's clothing". Due to restrictions placed on Germany after the First World War prohibiting bombers, it masqueraded as a civil airliner, although from conception the design was intended to provide the nascent Luftwaffe with a fast medium bomber; the best-recognised German bomber due to the distinctive, extensively glazed "greenhouse" nose of versions, the Heinkel He 111 was the most numerous Luftwaffe bomber during the early stages of World War II. The bomber fared well until the Battle of Britain, it proved capable of sustaining heavy damage and remaining airborne. As the war progressed, the He 111 was used in a variety of roles on every front in the European theatre, it was used as a strategic bomber during the Battle of Britain, a torpedo bomber in the Atlantic and Arctic, a medium bomber and a transport aircraft on the Western, Mediterranean, Middle Eastern, North African Front theatres.
The He 111 was upgraded and modified, but became obsolete during the latter part of the war. The German Bomber B project was not realised, which forced the Luftwaffe to continue operating the He 111 in combat roles until the end of the war. Manufacture of the He 111 ceased in September 1944, at which point piston-engine bomber production was halted in favour of fighter aircraft. With the German bomber force defunct, the He 111 was used for logistics. Production of the Heinkel continued after the war as the Spanish-built CASA 2.111. Spain received a batch of He 111H-16s in 1943 along with an agreement to licence-build Spanish versions, its airframe was produced in Spain under licence by Construcciones Aeronáuticas SA. The design differed in powerplant only being equipped with Rolls-Royce Merlin engines; the Heinkel's descendant continued in service until 1973. After its defeat in World War I, Germany was banned from operating an air force by the Treaty of Versailles. German re-armament began earnestly in the 1930s and was kept secret because it violated the treaty.
The early development of military bombers was disguised as a development program for civilian transport aircraft. Among the designers seeking to benefit from German re-armament was Ernst Heinkel. Heinkel decided to create the world's fastest passenger aircraft, a goal met with scepticism by Germany's aircraft industry and political leadership. Heinkel entrusted development to Siegfried and Walter Günter, both new to the company and untested. In June 1933 Albert Kesselring visited Heinkel's offices. Kesselring was head of the Luftwaffe Administration Office: at that point Germany did not have a State Aviation Ministry but only an aviation commissariat, the Luftfahrtkommissariat. Kesselring was hoping to build a new air force out of the Flying Corps being constructed in the Reichswehr, required modern aircraft. Kesselring convinced Heinkel to move his factory from Warnemünde to Rostock — with its factory airfield in the coastal "Marienehe" region of Rostock and bring in mass production, with a force of 3,000 employees.
Heinkel began work on the new design, which garnered urgency as the American Lockheed 12, Boeing 247 and Douglas DC-2 began to appear. Features of the He 111 were apparent in the Heinkel He 70; the first single-engined He 70 Blitz rolled off the line in 1932 and started breaking records. In the normal four-passenger version its speed reached 380 km/h when powered by a 447 kW BMW VI engine; the He 70 was designed with an elliptical wing, which the Günther brothers had incorporated into the Bäumer Sausewind before they joined Heinkel. This wing design became a feature in this and many subsequent designs they developed; the He 70 drew the interest of the Luftwaffe, looking for an aircraft with both bomber and transport capabilities. The He 111 was a twin-engine version of the Blitz, preserving the elliptical inverted gull wing, small rounded control surfaces and BMW engines, so that the new design was called the Doppel-Blitz; when the Dornier Do 17 displaced the He 70, Heinkel needed a twin-engine design to match its competitors.
Heinkel spent 200,000 man hours designing the He 111. The fuselage length was extended to just over 17.4 m/57 ft and wingspan to 22.6 m/74 ft. The first He 111 flew on 24 February 1935, piloted by chief test pilot Gerhard Nitschke, ordered not to land at the company's factory airfield at Rostock-Marienehe, as this was considered too short, but at the central Erprobungstelle Rechlin test facility, he ignored these orders and landed back at Marienehe. He said that the He 111 performed slow manoeuvres well and that there was no danger of overshooting the runway. Nitschke praised its high speed "for the period" and "very good-natured flight and landing characteristics", stable during cruising, gradual descent and single-engined flight and having no nose-drop when the undercarriage was operated. During the second test flight Nitschke revealed there was insufficient longitudinal stability during climb and flight at full power and the aileron controls required an unsatisfactory amount of force. By the end of 1935, prototypes V2 V4 had been produced under civilian registrations D-ALIX, D-ALES and D-AHAO.
D-ALES became the first prototype of the He 111 A-1 on 10 January 1936 and received recognition as the "fastest passenger aircraft in the world", as its speed exceeded 402 km/h. The design would have achieved a greater total speed had the 1,000 hp DB 600 inverted-V12 en
