The Hawker Typhoon is a British single-seat fighter-bomber, produced by Hawker Aircraft. It was intended to be a medium–high altitude interceptor, as a replacement for the Hawker Hurricane but several design problems were encountered and it never satisfied this requirement; the Typhoon was designed to mount twelve.303 inch Browning machine guns and be powered by the latest 2,000 hp engines. Its service introduction in mid-1941 was plagued with problems and for several months the aircraft faced a doubtful future; when the Luftwaffe brought the formidable Focke-Wulf Fw 190 into service in 1941, the Typhoon was the only RAF fighter capable of catching it at low altitudes. The Typhoon became established in roles such as long-range fighter. From late 1942 the Typhoon was equipped with bombs and from late 1943 RP-3 rockets were added to its armoury. With those weapons and its four 20mm Hispano autocannons, the Typhoon became one of the Second World War's most successful ground-attack aircraft. Before Hurricane production began in March 1937, Sydney Camm had embarked on designing its successor.
Two preliminary designs were larger than the Hurricane. These became known as the "N" and "R", because they were designed for the newly developed Napier Sabre and Rolls-Royce Vulture engines respectively. Both engines were designed for over 2,000 hp. Hawker submitted these preliminary designs in July 1937 but were advised to wait until a formal specification for a new fighter was issued. In March 1938, Hawker received from the Air Ministry, Specification F.18/37 for a fighter which would be able to achieve at least 400 mph at 15,000 feet and specified a British engine with a two-speed supercharger. The armament fitted was to be twelve.303 inch Browning machine guns with 500 rounds per gun, with a provision for alternative combinations of weaponry. Camm and his design team started formal development of the designs and construction of prototypes; the basic design of the Typhoon was a combination of traditional Hawker construction and more modern construction techniques. The forward fuselage and cockpit skinning was made up of large, removable duralumin panels, allowing easy external access to the engine and engine accessories and most of the important hydraulic and electrical equipment.
The wing had a span of 41 feet 7 inches, with a wing area of 279 sq ft. It was designed with a small amount of inverted gull wing bend; the airfoil was a NACA 22 wing section, with a thickness-to-chord ratio of 19.5% at the root tapering to 12% at the tip. The wing possessed great structural strength, provided plenty of room for fuel tanks and a heavy armament, while allowing the aircraft to be a steady gun platform; each of the inner wings incorporated two fuel tanks. Incorporated into the inner wings were inward-retracting landing gear with a wide track of 13 ft 6¾ in. By contemporary standards, the new design's wing was "thick", similar to the Hurricane before it. Although the Typhoon was expected to achieve over 400 mph in level flight at 20,000 ft, the thick wings created a large drag rise and prevented higher speeds than the 410 mph at 20,000 feet achieved in tests; the climb rate and performance above that level was considered disappointing. When the Typhoon was dived at speeds of over 500 mph, the drag rise caused buffeting and trim changes.
These compressibility problems led to Camm designing the Typhoon II known as the Tempest, which used much thinner wings with a laminar flow airfoil. The first flight of the first Typhoon prototype, P5212, made by Hawker's Chief test Pilot Philip Lucas from Langley, was delayed until 24 February 1940 because of the problems with the development of the Sabre engine. Although unarmed for its first flights, P5212 carried 12.303 in Brownings, set in groups of six in each outer wing panel. P5212 had a small tail-fin, triple exhaust stubs and no wheel doors fitted to the centre-section. On 9 May 1940 the prototype had a mid-air structural failure, at the join between the forward fuselage and rear fuselage, just behind the pilot's seat. Philip Lucas could see daylight through the split but instead of bailing out, landed the Typhoon and was awarded the George Medal. On 15 May, the Minister of Aircraft Production, Lord Beaverbrook, ordered that resources should be concentrated on the production of five main aircraft types.
As a result, development of the Typhoon was slowed, production plans were postponed and test flying continued at a reduced rate. As a result of the delays the second prototype, P5216, first flew on 3 May 1941: P5216 carried an armament of four belt-fed 20 mm (
Multirole combat aircraft
A multirole combat aircraft is a combat aircraft intended to perform different roles in combat. A multirole fighter is a multirole combat aircraft which is, at the same time a fighter aircraft; the term "Multirole" had been reserved for aircraft designed with the aim of using a common airframe for multiple tasks where the same basic airframe is adapted to a number of differing roles. The main motivation for developing multirole aircraft is cost reduction in using a common airframe. More roles can be added, such as aerial reconnaissance, forward air control, electronic-warfare aircraft. Attack missions include the subtypes air interdiction, suppression of enemy air defense, close air support. Multirole has been applied to one aircraft with both major roles, a primary air-to-air combat role, a secondary role like air-to-surface attack. However, those designed with an emphasis on aerial combat are regarded as air superiority fighters and deployed in that role though they are theoretically capable of ground attack.
A good example is the F-14 Tomcat versus the F/A-18 Hornet. In another instance, the Eurofighter Typhoon and Dassault Rafale are classified as multirole fighters; some aircraft, like the Saab JAS 39 Gripen, are called swing-role, to emphasize the ability of a quick role change, either at short notice, or within the same mission. According to the Military Dictionary: "the ability to employ a multi-role aircraft for multiple purposes during the same mission."According to BAE Systems, "an aircraft that can accomplish both air-to-air and air-to-surface roles on the same mission and swing between these roles offers true flexibility. This reduces cost, increases effectiveness and enhances interoperability with allied air forces"." Capability offers considerable cost-of-ownership benefits to operational commanders." Although the term "multirole aircraft" may be novel, certain airframes in history have proven versatile to multiple roles. In particular, the Junkers Ju 88 was renowned in Germany for being a "jack-of-all-trades", capable of performing as a bomber, dive bomber, night fighter, so on, much as the British de Havilland Mosquito did as a fast bomber/strike aircraft and night fighter.
The US joint forces F-4 Phantom II built by McDonnell-Douglas fits the definition of a multi-role aircraft in its various configurations of the basic airframe design. The various F-4 Phantom II configurations were used in air-to air, fighter bomber and suppression of enemy air defenses mission roles to name a few; the first use of the term was by the multinational European project named Multi-Role Combat Aircraft, formed in 1968 to produce an aircraft capable of tactical strike, aerial reconnaissance, air defense, maritime roles. The design was aimed to replace a multitude of different types in the cooperating air forces; the project produced the Panavia Tornado, which used the same basic design to undertake a variety of roles, the Tornado IDS variant and the Panavia Tornado ADV. By contrast, the F-15 Eagle, another fighter aircraft of that era was designed for air superiority and interception, with the mantra "not a pound for ground", but that program evolved into the F-15E Strike Eagle interdictor/strike derivative which retained the air-to-air combat lethality of earlier F-15s.
The newest fighter jet that fits the definition of'multi-role' is the Lockheed Martin F-35 Lightning II/Joint Strike Fighter, designed to perform stealth-based ground/naval strike, fighter and electronic warfare roles. Like a modern-day F-4, 3 variants of this aircraft fulfill the various strike and air defense roles among its joint service requirements: the standard variant is intended to replace the F-16 and A-10 in the USAF and other Western air forces, a STOVL version intended to replace the Harrier in US Marine Corps, British Royal Air Force and Royal Navy service, a carrier variant intended to replace the older F/A-18C/D for the US Navy and other F-18 operators; the F-35's design goal can be compared to its larger and more air superiority-focused cousin, the F-22 Raptor. Air superiority fighter Tactical bomber Interceptor aircraft Interdictor Fighter-bomber Attack aircraft Strike fighter Lead-in fighter trainer
Junkers Ju 87
The Junkers Ju 87 or Stuka was a German dive bomber and ground-attack aircraft. Designed by Hermann Pohlmann, it first flew in 1935; the Ju 87 made its combat debut in 1937 with the Luftwaffe's Condor Legion during the Spanish Civil War and served the Axis forces in World War II. The aircraft was recognisable by its inverted gull wings and fixed spatted undercarriage. Upon the leading edges of its faired main gear legs were mounted the Jericho-Trompete wailing sirens, becoming the propaganda symbol of German air power and the so-called blitzkrieg victories of 1939–1942; the Stuka's design included several innovations, including automatic pull-up dive brakes under both wings to ensure that the aircraft recovered from its attack dive if the pilot blacked out from the high g-forces. The Stuka operated with considerable success in close air support and anti-shipping at the outbreak of World War II, it led air assaults in the invasion of Poland in September 1939. Stukas were critical to the rapid conquest of Norway, the Netherlands and France in 1940.
Sturdy and effective against ground targets, the Stuka was, like many other dive bombers of the period, vulnerable to fighter aircraft. During the Battle of Britain its lack of manoeuvrability and defensive armament meant that it required a heavy fighter escort to operate effectively. After the Battle of Britain the Stuka was used in the Balkans Campaign, the African and Mediterranean theatres and the early stages of the Eastern Front where it was used for general ground support, as an effective specialised anti-tank aircraft and in an anti-shipping role. Once the Luftwaffe lost air superiority, the Stuka became an easy target for enemy fighter aircraft on all fronts, it was produced until 1944 for lack of a better replacement. By ground-attack versions of the Focke-Wulf Fw 190 had replaced the Stuka, but Stukas remained in service until the end of the war. An estimated 6,500 Ju 87s of all versions were built between 1936 and August 1944. Oberst Hans-Ulrich Rudel was the most successful Stuka ace and the most decorated German serviceman of the Second World War.
The Ju 87's principal designer, Hermann Pohlmann, held the opinion that any dive-bomber design needed to be simple and robust. This led to many technical innovations, such as the retractable undercarriage being discarded in favour of one of the Stuka's distinctive features, its fixed and "spatted" undercarriage. Pohlmann continued to carry on developing and adding to his ideas and those of Dipl Ing Karl Plauth, produced the Ju A 48 which underwent testing on 29 September 1928; the military version of the Ju A 48 was designated the Ju K 47. After the Nazis came to power, the design was given priority. Despite initial competition from the Henschel Hs 123, the Reichsluftfahrtministerium turned to the designs of Herman Pohlmann of Junkers and co-designer of the K 47, Karl Plauth. During the trials with the K 47 in 1932, the double vertical stabilisers were introduced to give the rear gunner a better field of fire; the main, what was to be the most distinctive, feature of the Ju 87 was its double-spar inverted gull wings.
After Plauth's death, Pohlmann continued the development of the Junkers dive bomber. The Ju A 48 registration D-ITOR, was fitted with a BMW 132 engine, producing 450 kW; the machine was fitted with dive brakes for dive testing. The aircraft was given a good evaluation and "exhibited good flying characteristics". Ernst Udet took an immediate liking to the concept of dive-bombing after flying the Curtiss F11C Goshawk; when Walther Wever and Robert Ritter von Greim were invited to watch Udet perform a trial flight in May 1934 at the Jüterbog artillery range, it raised doubts about the capability of the dive bomber. Udet began his dive at 1,000 m and released his 1 kg bombs at 100 m recovering and pulling out of the dive; the chief of the Luftwaffe Command Office Walther Wever, the Secretary of State for Aviation Erhard Milch, feared that such high-level nerves and skill could not be expected of "average pilots" in the Luftwaffe. Development continued at Junkers. Udet's "growing love affair" with the dive bomber pushed it to the forefront of German aviation development.
Udet went so far as to advocate that all medium bombers should have dive-bombing capabilities, which doomed the only dedicated, strategic heavy bomber design to enter German front-line service during the war years—the 30-metre wingspan He 177A—into having an airframe design that could perform "medium angle" dive-bombing missions, until Reichsmarschall Hermann Göring exempted the He 177A, Germany's only operational heavy bomber, in September 1942 from being given the task of such a mismatched mission profile for its large airframe. The design of the Ju 87 had begun in 1933 as part of the Sturzbomber-Programm; the Ju 87 was to be powered by the British Rolls-Royce Kestrel engine. Ten engines were ordered by Junkers on 19 April 1934 for two shillings and sixpence; the first Ju 87 prototype was built by AB Flygindustri in Sweden and secretly brought to Germany in late 1934. It was to have been completed in April 1935, due to the inadequate strength of the airframe, construction took until October 1935.
The complete Ju 87 V1 W. Nr.c 4921 took off for its maiden flight on 17 September 1935. The aircraft was given the registration D-UBYR; the flight report, by Hauptmann Willy Neuenhofen, stated the only problem was with the small radiator, which caused the engine to overheat. The Ju 87 V1, powe
The Tupolev Tu-22M is a supersonic, variable-sweep wing, long-range strategic and maritime strike bomber developed by the Tupolev Design Bureau. According to some sources, the bomber was believed to be designated Tu-26 at one time. During the Cold War, the Tu-22M was operated by the Soviet Air Forces in a missile carrier strategic bombing role, by the Soviet Naval Aviation in a long-range maritime anti-shipping role. Significant numbers remain in service with the Russian Air Force, as of 2014 more than 100 Tu-22Ms are in use. In 1962, with the introduction of the Tu-22, it became clear that the aircraft was inadequate in its role as a bomber. In addition to widespread unserviceability and maintenance issues, the Tu-22's handling characteristics proved to be dangerous, its landing speed was some 100 km/h greater than previous bombers and it had a tendency to pitch up and strike its tail upon landing. It was difficult to fly, had poor all-round visibility. In 1962, Tupolev commenced work on major update of the Tu-22.
The bureau planned to add a variable-sweep wing and uprated engines into the updated design. The design was tested at TsAGI's wind tunnels at Zhukovsky. During this time, traditionally a designer of fighter aircraft, developed the T-4, a four-engine titanium aircraft with canards. A response to the XB-70, it was to have a cruise speed of 3,200 km/h, requiring a massive research effort in order to develop the requisite technologies. Not to be outdone, whose expertise is with bombers, offered the Soviet Air Force a massively updated version of the Tu-22. Compared to the T-4, it was an evolutionary design, thus its appeal laid in its simplicity and low cost. However, the Soviet government was skeptical about the need to approve the development of a replacement aircraft so soon after the Tu-22 had just entered service; the Air Force and Tupolev, in order to save face with regards to the Tu-22's operational deficiencies and to stave off criticisms from the ICBM lobby, agreed to pass off the design as an update of the Tu-22 in their discussions with the government.
The aircraft was designated Tu-22M, given the OKB code "Aircraft 45", an internal designation of "AM". Their effort was successful as the government approved the design on 28 November 1967, decreed the development of the aircraft's main weapon, the Kh-22; the T-4 itself would make its first flight in 1972, but was cancelled. US intelligence had been aware of the existence of the aircraft since 1969, the first satellite photograph of the bomber would be taken in 1970; the existence of the aircraft was a shock to US intelligence as Nikita Khrushchev, the Soviet premier up to 1964, was adamant that ICBMs would render the bomber obsolete. As in the case of its contemporaries, the MiG-23 and Su-17 projects, the advantages of variable-sweep wing seemed attractive, allowing a combination of short take-off performance, efficient cruising, good high-speed, low-level flight; the result was a new swing wing aircraft named Samolyot 145, derived from the Tupolev Tu-22, with some features borrowed from the abortive Tu-98.
The Tu-22M was used its Kh-22 missile. The Tu-22M designation was used to help get approval for the bomber within the Soviet military and government system; the Tu-22M designation was used by the Soviet Union during the SALT II arms control negotiations, creating the impression that it was a modification of the Tu-22. Some suggested that the designation was deliberately deceptive, intended to hide the Tu-22M's performance. Other sources suggest. According to some sources, the Backfire-B/C production variants were believed to be designated Tu-26 by Russia, although this is disputed by many others; the US State and Defense Departments have used the Tu-22M designation for the Backfire. Production of all Tu-22M variants totalled 497 including pre-production aircraft. An initial attempt at modernizing the Tu-22M, Adaptation-45.03M, based around modernising the aircraft's radar, began in 1990, but was abandoned before reaching production. In 2007, work began on a new radar for the Tu-22M, the NV-45, first flown on a Tu-22M in 2008, with four more repaired Tu-22Ms refitted with NV-45 radars in 2014–2015.
A contract for a full mid-life upgrade, the Tu-22M3M was signed in September 2014. The aircraft is to receive a further modified NV-45M radar, together with new navigation equipment and a modified flight control system. A new self-defense electronic radar suit is fitted, replacing the tail gun of the existing Tu-22M3. Much of the new avionics are shared with the upgraded Tu-160M2. Armament is planned to be enhanced by adding the new Kh-32 missile, a modified version of the current Kh-22, the subsonic Kh-SD, the hypersonic Kh-MT, or the Kh-47M2 Kinzhal missiles. Deliveries of the Tu-22M3M are expected to begin in 2021. A separate, upgrade program is being carried out by the company Gefest & T, based on avionics developed for the Sukhoi Su-24 attack aircraft, including a new computer, a new navigation system and digital processing for the aircraft's radar; the upgrade is claimed to increase navigation accuracy and bomb delivery. A SVP-24-22-equipped Tu-22M underwent trials in 2009, the program has been ordered into production, with deliveries from 2012.
The two prototypes Tu-22M were delivered to Long Range Aviation's 42nd Combat Training Centre at Dyagilevo, near Ryazan, in February 1973. The aircraft began practice sorties in March. Within 20 days of the aircraft's delivery, the
Republic P-47 Thunderbolt
The Republic P-47 Thunderbolt was a World War II era fighter aircraft produced by the United States from 1941 through 1945. Its primary armament was eight.50-caliber machine guns and in the fighter-bomber ground-attack role it could carry five-inch rockets or a bomb load of 2,500 pounds. When loaded the P-47 weighed up to eight tons making it one of the heaviest fighters of the war; the P-47 was designed around the powerful Pratt & Whitney R-2800 Double Wasp engine, used by two U. S. Navy/U. S. Marine Corps fighters, the Grumman F6F Hellcat and the Vought F4U Corsair; the Thunderbolt was effective as a short-to-medium range escort fighter in high-altitude air-to-air combat and ground attack in both the World War II European and Pacific theaters. The P-47 was one of the main United States Army Air Forces fighters of World War II, served with Allied air forces including France and Russia. Mexican and Brazilian squadrons fighting alongside the U. S. flew the P-47. The armored cockpit was roomy and comfortable and the bubble canopy introduced on the P-47D offered good visibility.
A present-day U. S. ground-attack aircraft, the Fairchild Republic A-10 Thunderbolt II, takes its name from the P-47. The P-47 Thunderbolt was a design of Georgian immigrant Alexander Kartveli, was to replace the Seversky P-35, developed earlier by Russian immigrant Alexander P. de Seversky. Both had fled from their homeland to escape the Bolsheviks. In 1939, Republic Aviation designed the AP-4 demonstrator powered by a Pratt & Whitney R-1830 radial engine with a belly-mounted turbocharger. A small number of Republic P-43 Lancers were built but Republic had been working on an improved P-44 Rocket with a more powerful engine, as well as on the AP-10 fighter design; the latter was a lightweight aircraft powered by the Allison V-1710 liquid-cooled V-12 engine and armed with eight.50 in M2 Browning machine guns. The United States Army Air Corps backed the project and gave it the designation XP-47. In the spring of 1940, Republic and the USAAC concluded that the XP-44 and the XP-47 were inferior to Luftwaffe fighters.
Republic tried to improve the design, proposing the XP-47A but this failed. Kartveli designed a much larger fighter, offered to the USAAC in June 1940; the Air Corps ordered a prototype in September as the XP-47B. The XP-47A, which had little in common with the new design, was abandoned; the XP-47B was of all-metal construction with elliptical wings, with a straight leading edge, swept back. The air-conditioned cockpit was roomy and the pilot's seat was comfortable—"like a lounge chair", as one pilot put it; the canopy doors hinged upward. Main and auxiliary self-sealing fuel tanks were placed under the cockpit, giving a total fuel capacity of 305 U. S. gal. Power came from a Pratt & Whitney R-2800 Double Wasp two-row 18-cylinder radial engine producing 2,000 hp —the same engine that would power the prototype Vought XF4U-1 fighter to just over 400 mph in October 1940—with the Double Wasp on the XP-47B turning a four-bladed Curtiss Electric constant-speed propeller of 146 in in diameter; the loss of the AP-4 prototype to an engine fire ended Kartveli's experiments with tight-fitting cowlings, so the engine was placed in a broad cowling that opened at the front in a "horse collar"-shaped ellipse.
The cowling admitted cooling air for the engine and right oil coolers, the turbosupercharger intercooler system. The engine exhaust gases were routed into a pair of wastegate-equipped pipes that ran along each side of the cockpit to drive the turbosupercharger turbine at the bottom of the fuselage, about halfway between cockpit and tail. At full power, the pipes glowed red at the turbine spun at 21,300 rpm; the complicated turbosupercharger system with its ductwork gave the XP-47B a deep fuselage, the wings had to be mounted in a high position. This was difficult since long-legged main landing gear struts were needed to provide ground clearance for the enormous propeller. To reduce the size and weight of the undercarriage struts and so that wing-mounted machine guns could be fitted, each strut was fitted with a mechanism by which it telescoped out 9 in when extended; the XP-47B was heavy compared with contemporary single-engined fighters, with an empty weight of 9,900 lb, or 65 per cent more than the YP-43.
Kartveli said, "It will be a dinosaur, but it will be a dinosaur with good proportions". The armament was eight.50 caliber "light-barrel" Browning AN/M2 machine guns, four in each wing. The guns were staggered to allow feeding from side-by-side ammunition boxes, each with 350 rounds. All eight guns gave the fighter a combined rate of fire of 100 rounds per second; the XP-47B first flew on 6 May 1941 with Lowry P. Brabham at the controls. Although there were minor problems, such as some cockpit smoke that turned out to be due to an oil drip, the aircraft proved impressive in its early trials, it was lost in an accident on 8 August 1942 but before that mishap, the prototype had achieved a level speed of 412 mph at 25,800 ft altitude and had demonstrated a climb from sea level to 15,000 ft in five minutes. The XP-47B gave the newly reorganized United States Army Air Forces cause for both optimism and apprehension. While possessing good performance and firepower, the XP-47B had its share of teething problems: Its sheer size and limited ground-propeller clearance in a fuselage-level attitude made for challenging takeoffs which required long runways—the pilot had to hold the tail low until considerable speed was attained on the initial run.
The sideways-opening can
Bulgarian Air Force
The Bulgarian Air Force is one of the three branches of the Military of Bulgaria, the other two being the Bulgarian Navy and Bulgarian land forces. Its mission is to guard and protect the sovereignty of Bulgarian airspace, to provide aerial support and to assist the Land Forces in case of war; the Bulgarian Air Force is one of the oldest air forces in the world. In recent times it has been taking part in numerous NATO missions and exercises in Europe; the current commanding officer of the Bulgarian Air Force is Major General Constantin Popov. The Bulgarian Air Force dates back to the end of the 19th century. In 1892 at the Plovdiv International Fair two lieutenants of the Bulgarian Army flew in the'La France' balloon of the Frenchman Godard. Inspired by the flight, they succeeded to convince the General Staff that the Bulgarian Army should build a balloon force; the Imperial Aviation School in St. Petersburg enrolled Lieutenant Vasil Zlatarov as a student, following numerous refusals from military schools around Europe to teach Bulgarian officers to use airships.
On 20 April 1906 "Vazduhoplavatelno Otdelenie" was created to operate observation balloons for the army being a part of Railway Battalion. After graduation Lt. Zlatarov was appointed its first commander. After operating small balloons, in 1911 a bigger Godard balloon was bought, in 1912 the first balloon Sofia-1 was constructed in Bulgaria, of materials bought from Russia. In 1910 a Russian aircraft engineer, Boris Maslennikov, was invited to Bulgaria, where he presented his airplane, a modification of the French Farman III. Following his demonstration, assisted by Vasil Zlatarov over the hippodrome in Sofia, the Bulgarian Government decided to acquire airplanes for The Aviation Corps. In early 1912 thirteen army officers were sent abroad for training as pilots and orders were placed for five French and German airplanes; the officers sent to France completed their training first and returned to Bulgaria in July 1912. The same year Bulgaria received its first airplane – Bleriot XXI with which on 13 August 1912 Simeon Petrov flew to become the first Bulgarian to pilot an airplane over Bulgaria.
Following the outbreak of the First Balkan War, Bulgarian pilots still abroad hastily procured aircraft to be shipped home after them and foreign volunteer pilots converged from all over Europe in Bulgaria. After the front lines had stabilized, an Aeroplane Platoon was established at a new airfield close to the fighting. Intelligence about the Turkish army strength and dispositions in the Edirne was required, on 16 October 1912, two aviators performed a reconnaissance flight over the city in an Albatros FIII biplane, dropping two bombs, not only the first military mission performed by a Bulgarian aircraft, but the first combat use of an aircraft in Europe; that month the Bulgarian Aviation Corps was expanded to three Aeroplane Platoons. Foreign volunteers began flying operational sorties alongside Bulgarian pilots and carried out reconnaissance, leaflet-dropping and bombing missions. During the war at least three aircraft were shot down. Considerable help was received from the Russians in terms of aircraft and training.
Due to low aircraft serviceability and frequent accidents, the number of missions flown was low. Despite that, the Bulgarian airmen and their foreign helpers were able to gather enough intelligence for the Army General Staff to use in the capture of the city. Although inflicting little physical damage, the bombs had a devastating effect on the defending Turkish garrison's morale and played a crucial part in the fall of the city, until considered nearly impregnable. During the First Balkan War Bulgarian aviation undertook 70 combat sorties, including 11 bombing raids, during the Second Balkan War it undertook 6 sorties. All in all, during both wars, there were including non-combat; the aircraft used were Blériot XI and XXI, Sommer, Albatros FIII, Farman VII and Nieuport IV. The Kingdom of Bulgaria entered World War I as an ally of the Central Powers on October 4, 1915; the Aeroplane Section of the Bulgarian Army was deployed to Kumanovo Airfield in support of advancing Bulgarian forces, but bad weather prevented any flying.
Until they had completed 11 combat sorties from an airfield in Sofia. As the frontline advanced, the unit re-deployed to airfields near Belitsa and Xanthi, in modern Greece. Newly acquired German LVG aircraft were hastily pressed into action. Two more airfields were constructed near Levunovo; the Allies began flying reconnaissance and bomber sorties against Bulgarian units on the Southern Balkan Front. Throughout World War I Bulgarian military aviation experienced a steady increase in both numbers and quality of aircraft; the First Aeroplane Section was attached to the Second Bulgarian Army. It flew 255 sorties compared to 397 flown by the four squadrons of the Entente it opposed, operated the following types:12 LVG B. II – reconnaissance aircraft, the first group of six arriving in November 1915; those two seaters were used as fighters by the Bulgarians, as dedicated "scouts" were not available. 13 Otto C. I – a twin-tailed pusher bomber; the first Otto in arrived in May 1916. 18 Albatros C. III – reconnaissance aircraft used as trainers.
First delivery in August 1916. 12 DFW C. V – reconnaissance aircraft, first arriving in August 1917. 6 Roland D. II fighters. During July 1917 the first of these arrived with the Section. 6 Roland D. III fighters
A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission or from a combination of fission and fusion reactions. Both bomb types release large quantities of energy from small amounts of matter; the first test of a fission bomb released an amount of energy equal to 20,000 tons of TNT. The first thermonuclear bomb test released energy equal to 10 million tons of TNT. A thermonuclear weapon weighing little more than 2,400 pounds can release energy equal to more than 1.2 million tons of TNT. A nuclear device no larger than traditional bombs can devastate an entire city by blast and radiation. Since they are weapons of mass destruction, the proliferation of nuclear weapons is a focus of international relations policy. Nuclear weapons have been used twice in war, both times by the United States against Japan near the end of World War II. On August 6, 1945, the U. S. Army Air Forces detonated a uranium gun-type fission bomb nicknamed "Little Boy" over the Japanese city of Hiroshima.
S. Army Air Forces detonated a plutonium implosion-type fission bomb nicknamed "Fat Man" over the Japanese city of Nagasaki; these bombings caused injuries that resulted in the deaths of 200,000 civilians and military personnel. The ethics of these bombings and their role in Japan's surrender are subjects of debate. Since the atomic bombings of Hiroshima and Nagasaki, nuclear weapons have been detonated over two thousand times for testing and demonstration. Only a few nations are suspected of seeking them; the only countries known to have detonated nuclear weapons—and acknowledge possessing them—are the United States, the Soviet Union, the United Kingdom, China, India and North Korea. Israel is believed to possess nuclear weapons, though, in a policy of deliberate ambiguity, it does not acknowledge having them. Germany, Turkey and the Netherlands are nuclear weapons sharing states. South Africa is the only country to have independently developed and renounced and dismantled its nuclear weapons.
The Treaty on the Non-Proliferation of Nuclear Weapons aims to reduce the spread of nuclear weapons, but its effectiveness has been questioned, political tensions remained high in the 1970s and 1980s. Modernisation of weapons continues to this day. There are two basic types of nuclear weapons: those that derive the majority of their energy from nuclear fission reactions alone, those that use fission reactions to begin nuclear fusion reactions that produce a large amount of the total energy output. All existing nuclear weapons derive some of their explosive energy from nuclear fission reactions. Weapons whose explosive output is from fission reactions are referred to as atomic bombs or atom bombs; this has long been noted as something of a misnomer, as their energy comes from the nucleus of the atom, just as it does with fusion weapons. In fission weapons, a mass of fissile material is forced into supercriticality—allowing an exponential growth of nuclear chain reactions—either by shooting one piece of sub-critical material into another or by compression of a sub-critical sphere or cylinder of fissile material using chemically-fueled explosive lenses.
The latter approach, the "implosion" method, is more sophisticated than the former. A major challenge in all nuclear weapon designs is to ensure that a significant fraction of the fuel is consumed before the weapon destroys itself; the amount of energy released by fission bombs can range from the equivalent of just under a ton to upwards of 500,000 tons of TNT. All fission reactions generate the remains of the split atomic nuclei. Many fission products are either radioactive or moderately radioactive, as such, they are a serious form of radioactive contamination. Fission products are the principal radioactive component of nuclear fallout. Another source of radioactivity is the burst of free neutrons produced by the weapon; when they collide with other nuclei in surrounding material, the neutrons transmute those nuclei into other isotopes, altering their stability and making them radioactive. The most used fissile materials for nuclear weapons applications have been uranium-235 and plutonium-239.
Less used has been uranium-233. Neptunium-237 and some isotopes of americium may be usable for nuclear explosives as well, but it is not clear that this has been implemented, their plausible use in nuclear weapons is a matter of dispute; the other basic type of nuclear weapon produces a large proportion of its energy in nuclear fusion reactions. Such fusion weapons are referred to as thermonuclear weapons or more colloquially as hydrogen bombs, as they rely on fusion reactions between isotopes of hydrogen. All such weapons derive a significant portion of their energy from fission reactions used to "trigger" fusion reactions, fusion reactions can themselves trigger additional fission reactions. Only six countries—United States, United Kingdom, China and India—have conducted thermonuclear weapon tests. North Korea claims to have tested a fusion weapon as of January 2016. Thermonuclear weapons a