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96-469: The SNCASO SO.9000 Trident is a French jet and rocket powered interceptor aircraft built by aircraft manufacturer SNCASO during the 1950s. As part of a wider effort to re-build French military power during the late 1940s and to furnish France with advanced, new domestically produced designs, a request for a supersonic -capable point-defence interceptor aircraft to equip the French Air Force

192-479: A belly landing on 19 September. In May 1956 the Air Force placed an order for a batch of six pre-production aircraft, and a supplementary contract followed for four additional aircraft, although this later contract was cancelled on 24 October 1957 due to budget cutbacks. These aircraft differed from the first three prototypes by substituting a pair of 10.79 kN (2,430 lbf) Turbomeca Gabizo turbojets for

288-569: A boxcar . Similarly, their pilots were given less training in combat maneuvers, and more in radio-directed pursuit. The Soviets' main interceptor was initially the Su-9 , which was followed by the Su-15 and the MiG-25 "Foxbat". The auxiliary Tu-128 , an area range interceptor, was notably the heaviest fighter aircraft ever to see service in the world. The latest and most advanced interceptor aircraft in

384-540: A license-produced version of the British Armstrong Siddeley Viper, were installed. The aircraft made its first flight with its new engines in March 1955. Powered by these engines, the aircraft soon proved its ability to exceed Mach 1 during a shallow dive even without the added thrust of the rocket motor. In April 1956, it was decided to end flight testing with the surviving Trident I. During

480-517: A batch of six pre-production aircraft in 1956 to further develop the aircraft so it could serve as a short-range interceptor. Only six of these nine aircraft were ultimately completed, of which all three prototypes were damaged or destroyed in accidents before the programme was cancelled in 1958 despite their record-setting performance. During the late 1940s, following the end of the Second World War , France quickly set about its recovery and

576-485: A brief period of time they fared rapid development in both speed, range, and altitude. At the end of the 1960s, a nuclear attack became unstoppable with the introduction of ballistic missiles capable of approaching from outside the atmosphere at speeds as high as 3 to 4 miles per second (5 to 7 km/s). The doctrine of mutually assured destruction replaced the trend of defense strengthening, making interceptors less strategically logical. The utility of interceptors waned as

672-425: A channel becomes supersonic, one significant change takes place. The conservation of mass flow rate leads one to expect that contracting the flow channel would increase the flow speed (i.e. making the channel narrower results in faster air flow) and at subsonic speeds this holds true. However, once the flow becomes supersonic, the relationship of flow area and speed is reversed: expanding the channel actually increases

768-462: A chosen aspect of performance. A "point defense interceptor" is of a lightweight design, intended to spend most of its time on the ground located at the defended target, and able to launch on demand, climb to altitude, manoeuvre and then attack the bomber in a very short time, before the bomber can deploy its weapons. At the end of Second World War, the Luftwaffe ' s most critical requirement

864-459: A command centre in the Horse Guards building. The Pup proved to have too low performance to easily intercept Gotha G.IV bombers, and the superior Sopwith Camels supplanted them. The term "interceptor" was in use by 1929. Through the 1930s, bomber aircraft speeds increased so much that conventional interceptor tactics appeared impossible. Visual and acoustic detection from the ground had

960-546: A gas, it increases proportionally to the square root of the absolute temperature , and since atmospheric temperature generally decreases with increasing altitude between sea level and 11,000 meters (36,089 ft), the speed of sound also decreases. For example, the standard atmosphere model lapses temperature to −56.5 °C (−69.7 °F) at 11,000 meters (36,089 ft) altitude, with a corresponding speed of sound (Mach   1) of 295.0 meters per second (967.8 ft/s; 659.9 mph; 1,062 km/h; 573.4 kn), 86.7% of

1056-511: A mixed-propulsion approach, using a combination of rocket and turbojet engines. During 1944, a new company, Société d'Etudes pour la Propulsion par Réaction (SEPR), had been founded for the purpose of developing France's own domestic rocket engines. Accordingly, SNCASO received a request from the Air Staff to begin studies for rocket-powered point-defence interceptors with auxiliary turbojets in 1948. During October, SNCASO commenced work upon

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1152-472: A much larger area from attack, depending on greater detection capabilities, both in the aircraft themselves and operating with AWACS, rather than high speed to reach targets. The exemplar of this concept was the Tupolev Tu-28 . The later Panavia Tornado ADV was able to achieve long range in a smaller airframe through the use of more efficient engines. Rather than focusing on acceleration and climb rate,

1248-694: A pair of proposals for interceptor aircraft, the first such designation in the US. One proposal was for a single-engine fighter, the other for a twin-engine. Both were required to reach an altitude of 20,000 feet (6,100 m) in six minutes as a defense against bomber attack. Kelsey said later that he used the interceptor designation to sidestep a hard USAAC policy restricting fighters to 500 pounds (230 kg) of armament. He wished for at least 1,000 pounds (450 kg) of armament so that American fighters could dominate their battles against all opponents, fighters included. The two aircraft resulting from these proposals were

1344-510: A range of only a few miles, which meant that an interceptor would have insufficient time to climb to altitude before the bombers reached their targets. Standing combat air patrols were possible but only at great cost. The conclusion at the time was that " the bomber will always get through ". The invention of radar made possible early, long-range detection of aircraft on the order of 100 miles (160 km), both day and night and in all weather. A typical bomber might take twenty minutes to cross

1440-403: A record of 2 minutes, 37 seconds to 15,000 metres (49,213 ft) on 4 April while the third pre-production aircraft unofficially reached 22,800 metres (74,800 ft) on 17 January and then made its officially-observed record-breaking altitude of 24,217 metres (79,452 ft) on 2 May, shortly after the programme was cancelled on 26 April. The last three incomplete airframes were scrapped, but

1536-451: A request to French aircraft companies for a high-speed, lightweight interceptor aircraft that harnessed either turbojet or rocket propulsion, or some combination thereof. Amongst the specified requirements given were the ability to attain Mach 1.3, a relatively high climb rate, and the possibility of deploying the aircraft from austere airstrips. Amongst the various responses from French industry

1632-424: A series of design studies in response. One particular design by aircraft designer Lucien Servanty was favoured by the company. This was a shoulder-wing monoplane capable of supersonic speeds using a single SEPR-built rocket engine in the fuselage augmented with a set of wingtip-mounted turbojets; operationally, both types of engines were to be used to perform a rapid climb and interception at high altitudes, while

1728-415: A sharp object, there is no air between the nose and the shock wave: the shock wave starts from the nose.) As the Mach number increases, so does the strength of the shock wave and the Mach cone becomes increasingly narrow. As the fluid flow crosses the shock wave, its speed is reduced and temperature, pressure, and density increase. The stronger the shock, the greater the changes. At high enough Mach numbers

1824-619: A step and roughly doubled operational altitudes. Although radars also improved in performance, the gap between offense and defense was dramatically reduced. Large attacks could so confuse the defense's ability to communicate with pilots that the classic method of manual ground controlled interception was increasingly seen as inadequate. In the United States, this led to the introduction of the Semi-Automatic Ground Environment to computerize this task, while in

1920-599: A supersonic compressible flow can be found from the Rayleigh supersonic pitot equation (above) using parameters for air: M ≈ 0.88128485 ( q c p + 1 ) ( 1 − 1 7 M 2 ) 2.5 {\displaystyle \mathrm {M} \approx 0.88128485{\sqrt {\left({\frac {q_{c}}{p}}+1\right)\left(1-{\frac {1}{7\,\mathrm {M} ^{2}}}\right)^{2.5}}}} where: As can be seen, M appears on both sides of

2016-769: A supersonic compressible flow is derived from the Rayleigh supersonic pitot equation: p t p = [ γ + 1 2 M 2 ] γ γ − 1 ⋅ [ γ + 1 1 − γ + 2 γ M 2 ] 1 γ − 1 {\displaystyle {\frac {p_{t}}{p}}=\left[{\frac {\gamma +1}{2}}\mathrm {M} ^{2}\right]^{\frac {\gamma }{\gamma -1}}\cdot \left[{\frac {\gamma +1}{1-\gamma +2\gamma \,\mathrm {M} ^{2}}}\right]^{\frac {1}{\gamma -1}}} Mach number

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2112-483: A two-chamber SEPR 631 rocket engine. The pre-production aircraft were equipped with two Turbomeca Gabizo turbojets and a SEPR 631. The fourth incomplete pre-production aircraft would have served as a prototype for the Trident III family, all of which would have been fitted with two afterburning Turbomeca Gabizo turbojets and a SEPR 631. The IIIB would have had a lengthened fuselage and a revised canopy . The nose of

2208-453: A very high fuel consumption. This led fighter prototypes emphasizing acceleration and operational ceiling, with a sacrifice on the loiter time, essentially limiting them to point defense role. Such were the mixed jet/rocket power Republic XF-91 or Saunders Roe SR.53 . The Soviet and Western trials with zero-length launch were also related. None of these found practical use. Designs that depended solely on jet engines achieved more success with

2304-407: Is a dimensionless quantity. If M  < 0.2–0.3 and the flow is quasi-steady and isothermal , compressibility effects will be small and simplified incompressible flow equations can be used. The Mach number is named after the physicist and philosopher Ernst Mach , in honour of his achievements, according to a proposal by the aeronautical engineer Jakob Ackeret in 1929. The word Mach

2400-642: Is a function of temperature and true airspeed. Aircraft flight instruments , however, operate using pressure differential to compute Mach number, not temperature. Assuming air to be an ideal gas , the formula to compute Mach number in a subsonic compressible flow is found from Bernoulli's equation for M < 1 (above): M = 5 [ ( q c p + 1 ) 2 7 − 1 ] {\displaystyle \mathrm {M} ={\sqrt {5\left[\left({\frac {q_{c}}{p}}+1\right)^{\frac {2}{7}}-1\right]}}\,} The formula to compute Mach number in

2496-473: Is always capitalized since it derives from a proper name, and since the Mach number is a dimensionless quantity rather than a unit of measure , the number comes after the word Mach. It was also known as Mach's number by Lockheed when reporting the effects of compressibility on the P-38 aircraft in 1942. Mach number is a measure of the compressibility characteristics of fluid flow : the fluid (air) behaves under

2592-446: Is that interceptors often look very impressive on paper, typically outrunning, outclimbing and outgunning slower fighter designs. However, pure interceptors fare poorly in fighter-to-fighter combat against the same "less capable" designs due to limited maneuverability especially at low altitudes and speeds. In the spectrum of various interceptors, one design approach especially shows sacrifices necessary to achieve decisive benefit in

2688-621: Is that range of speeds within which the airflow over different parts of an aircraft is between subsonic and supersonic. So the regime of flight from Mcrit up to Mach 1.3 is called the transonic range. Aircraft designed to fly at supersonic speeds show large differences in their aerodynamic design because of the radical differences in the behavior of flows above Mach 1. Sharp edges, thin aerofoil sections, and all-moving tailplane / canards are common. Modern combat aircraft must compromise in order to maintain low-speed handling. Flight can be roughly classified in six categories: At transonic speeds,

2784-645: The Convair F-106 Delta Dart , Sukhoi Su-15 , and English Electric Lightning . Through the 1960s and 1970s, the rapid improvements in design led to most air-superiority and multirole fighters , such as the Grumman F-14 Tomcat and McDonnell Douglas F-15 Eagle , having the performance to take on the point defense interception role, and the strategic threat moved from bombers to intercontinental ballistic missiles (ICBMs). Dedicated interceptor designs became increasingly rare, with

2880-601: The F-104 Starfighter (initial A version) and the English Electric Lightning . The role of crewed point defense designs was reassigned to uncrewed interceptors— surface-to-air missiles (SAMs)—which first reached an adequate level in 1954–1957. SAM advancements ended the concept of massed high-altitude bomber operations, in favor of penetrators (and later cruise missiles ) flying a combination of techniques colloquially known as "flying below

2976-627: The F-86D and F-89 Scorpion . In the late 1940s ADC started a project to build a much more advanced interceptor under the 1954 interceptor effort, which eventually delivered the F-106 Delta Dart after a lengthy development process. Further replacements were studied, notably the NR-349 proposal during the 1960s, but came to nothing as the USSR strengthened their strategic force with ICBMs. Hence,

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3072-524: The Matra 052 AAM. It subsequently attained a speed of Mach 1.96 without the missile at a height of 19,100 m (62,664 ft). On 21 May 1957, the aircraft exploded in mid-air during a practice flight for the Paris Air Show that was probably caused when the highly volatile Furaline and nitric acid accidentally mixed and exploded, killing the pilot. The third prototype continued flying until it made

3168-554: The Messerschmitt Me 163 Komet , which was the only rocket-powered, crewed military aircraft to see combat. To a lesser degree, the Mikoyan-Gurevich MiG-15 , which had heavy armament specifically intended for anti-bomber missions, was also a specialized day interceptor. Night fighters and bomber destroyers are interceptors of the heavy type, although initially they were rarely referred to as such. In

3264-483: The Space Shuttle and various space planes in development. The subsonic speed range is that range of speeds within which, all of the airflow over an aircraft is less than Mach 1. The critical Mach number (Mcrit) is lowest free stream Mach number at which airflow over any part of the aircraft first reaches Mach 1. So the subsonic speed range includes all speeds that are less than Mcrit. The transonic speed range

3360-400: The sound barrier ), a large pressure difference is created just in front of the aircraft . This abrupt pressure difference, called a shock wave , spreads backward and outward from the aircraft in a cone shape (a so-called Mach cone ). It is this shock wave that causes the sonic boom heard as a fast moving aircraft travels overhead. A person inside the aircraft will not hear this. The higher

3456-673: The 18-month-long flight test programme, the Trident I had completed over 100 flights, having eventually reached a maximum recorded speed of Mach 1.8 and a peak altitude of 20,000 metres (65,000 ft). A total of 24 of these flights had been flown using the rocket engine. According to Pelt, the French Air Force were impressed by the performance of the Trident, and were keen to adopt an improved operationally-capable model into service. Two prototype SO.9050 Trident IIs were ordered in 1954 and primarily differed from their predecessors by

3552-475: The Air Force after it had decided upon the Dassault Mirage III to satisfy its interceptor requirement. Two aircraft built, powered by two Turbomeca Marboré II turbojet engines with a single three-chamber SEPR 481 rocket engine. Three prototypes and six pre-production aircraft, but only three of the latter were completed. The prototypes were powered by a pair of Dassault MD.30 Viper turbojets and

3648-554: The Air Force continued the flight testing until late in the year. This allowed the Trident II to establish various unofficial records before the surviving aircraft were scrapped. These included a maximum speed of Mach 1.97 on 23 July, an altitude of 26,000 metres (85,302 ft) on 6 October that was the highest altitude to be flown by a turbojet and a time-to-height of 2 minutes, 15 seconds to 15,000 metres on 8 July. None of these later accomplishments were publicised to avoid upsetting

3744-476: The F-106 ended up serving as the primary USAF interceptor into the 1980s. As the F-106 was retired, intercept missions were assigned to the contemporary F-15 and F-16 fighters, among their other roles. The F-16, however, was originally designed for air superiority while evolving into a versatile multirole fighter. The F-15, with its Mach 2.5 maximum speed enabling it to intercept the fastest enemy aircraft (namely

3840-769: The IIIC would have been enlarged to accommodate a larger fire-control radar. The first prototype of the SO.9000 has been on public display since 1956 at the Musée de l'Air et de l'Espace , near Paris . Data from X-Planes of Europe: Secret Research Aircraft from the Golden Age 1946-1974 ; French Secret Projects 1: Post War Fighters General characteristics Performance Aircraft of comparable role, configuration, and era Interceptor aircraft For daytime operations, conventional light fighters have normally filled

3936-488: The MD.30 engines. Other changes included a redesigned nose to accommodate a fire-control radar and the addition of a hardpoint below the fuselage for a Matra R.511 AAM. The first pre-production aircraft (the fourth Trident II) was first flown on 3 May 1957. In an unsuccessful attempt to stave off cancellation, SNACSO made efforts to establish new time-to-height and altitude records in 1958. The first pre-production aircraft set

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4032-750: The McDonnell Douglas F-4 Phantom as its primary interceptor from the mid-1970s, with the air defence variant (ADV) of the Panavia Tornado being introduced in the 1980s. The Tornado was eventually replaced with a multirole design, the Eurofighter Typhoon . The Shenyang J-8 is a high-speed, high-altitude Chinese-built single-seat interceptor. Initially designed in the early 1960s to counter US-built B-58 Hustler bombers, F-105 Thunderchief fighter-bombers and Lockheed U-2 reconnaissance planes, it still retains

4128-669: The MiG-25 Foxbat), is also not a pure interceptor as it has exceptional agility for dogfighting based upon the lessons learned from Vietnam; the F-15E Strike Eagle variant adds air interdiction while retaining the interception and air-to-air combat of other F-15s. Presently, the F-22 is the USA's latest combat aircraft that serves in part as an interceptor due to its Mach 2+ speed as well as supercruise capabilities, however it

4224-673: The Soviet (now Russian) inventory is the MiG-31 "Foxhound". Improving on some of the flaws on the proceeding MiG-25, the MiG-31 has better low altitude and low speed performance, in addition to carrying an internal cannon. Russia, despite merging the PVO into the VVS, continues to maintain its dedicated MiG-31 interceptor fleet. In 1937, USAAC lieutenants Gordon P. Saville and Benjamin S. Kelsey devised

4320-462: The UK it led to enormously powerful radars to improve detection time. The introduction of the first useful surface to air missiles in the 1950s obviated the need for fast reaction time interceptors as the missile could launch almost instantly. Air forces increasingly turned to much larger interceptor designs, with enough fuel for longer endurance, leaving the point-defense role to the missiles. This led to

4416-599: The abandonment of a number of short-range designs like the Avro Arrow and Convair F-102 in favor of much larger and longer-ranged designs like the North American F-108 and MiG-25 . In the 1950s and 1960’s during the Cold War , a strong interceptor force was crucial for the opposing superpowers as it was the best means to defend against an unexpected nuclear attack by strategic bombers . Hence, for

4512-470: The ability to 'sprint' at Mach 2+ speeds, and later versions can carry medium-range PL-12/SD-10 MRAAM missiles for interception purposes. The PLAAF/PLANAF currently still operates approximately 300 or so J-8s of various configurations. Several other countries also introduced interceptor designs, although in the 1950s–1960s several planned interceptors never came to fruition, with the expectation that missiles would replace bombers. The Argentine FMA I.Ae. 37

4608-458: The aircraft themselves. They were first to introduce all-weather avionics , assuring successful operations during night, rain, snow, or fog. Countries that were strategically dependent on surface fleet, most notably US and UK, maintained also fleet defense fighters , such as the F-14 Tomcat . During the Cold War , an entire military service, not just an arm of the pre-existing air force,

4704-697: The bombing raids. Rocket-boosted variants of both of Germany's jet fighters; the Me 262 in its "C" subtype series, all nicknamed "home protector" ( Heimatschützer , in four differing formats) and the planned He 162 E subtype, using one of the same BMW 003R turbojet/rocket "mixed-power" engine as the Me 262C-2b Heimatschützer II , but were never produced in quantity. In the initial stage of Cold War , bombers were expected to attack flying higher and faster, even at transonic speeds. Initial transonic and supersonic fighters had modest internal fuel tanks in their slim fuselages, but

4800-631: The defending fighters. The Me 163 required an airbase, however, which were soon under constant attack. Following the Emergency Fighter Program , the Germans developed even odder designs, such as the Bachem Ba 349 Natter , which launched vertically and thus eliminated the need for an airbase. In general all these initial German designs proved difficult to operate, often becoming death traps for their pilots, and had little effect on

4896-458: The design emphasis is on range and missile carrying capacity, which together translate into combat endurance, look-down/shoot-down radars good enough to detect and track fast moving interdictors against ground clutter , and the capability to provide guidance to air-to-air missiles (AAM) against these targets. High speed and acceleration was put into long-range and medium-range AAMs, and agility into short range dog fighting AAMs, rather than into

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4992-464: The detection zone of early radar systems, time enough for interceptor fighters to start up, climb to altitude and engage the bombers. Ground controlled interception required constant contact between the interceptor and the ground until the bombers became visible to the pilots and nationwide networks like the Dowding system were built in the late 1930s to coordinate these efforts. During World War II

5088-540: The early Cold War era the combination of jet -powered bombers and nuclear weapons created air force demand for highly capable interceptors; it is in regards to this period that the term is perhaps most recognized and used. Cold War-era interceptors became increasingly distinct from their air superiority counterparts, with the former often sacrificing range, endurance, and maneuverability for speed, rate of climb , and armament dedicated to attacking large strategic bombers . Examples of classic interceptors of this era include

5184-486: The early test flights of the SO.9000 were "hairy" prior to the installation of the rocket motor in September 1954. During the first flight of the second Trident I prototype on 1 September 1953, the aircraft crashed after struggling to gain altitude after takeoff and collided with a utility pole , resulting in the separation of the nose section and Guignard sustaining severe injuries. On 16 January 1954, test flights using

5280-405: The effectiveness of interceptor aircraft meant that bombers often needed to be escorted by long range fighter aircraft. Many aircraft were able to be fitted with Aircraft interception radar , further facilitating the interception of enemy aircraft. The introduction of jet power increased flight speeds from around 300 miles per hour (500 km/h) to around 600 miles per hour (1,000 km/h) in

5376-473: The equation, and for practical purposes a root-finding algorithm must be used for a numerical solution (the equation is a septic equation in M and, though some of these may be solved explicitly, the Abel–Ruffini theorem guarantees that there exists no general form for the roots of these polynomials). It is first determined whether M is indeed greater than 1.0 by calculating M from the subsonic equation. If M

5472-481: The event of a war between the Soviet Union and NATO. With the advent of low flying cruise-missiles and high-altitude AA-missiles the flight profile was changed, but regained the interceptor profile with the final version J 35J. Mach number The Mach number ( M or Ma ), often only Mach , ( / m ɑː k / ; German: [max] ) is a dimensionless quantity in fluid dynamics representing

5568-407: The external fuel lines were detached. However, keeping QRA aircraft at this state of readiness was physically and mentally draining to the pilots and was expensive in terms of fuel. As an alternative, longer-range designs with extended loiter times were considered. These area defense interceptors or area defense fighters were in general larger designs intended to stay on lengthy patrol and protect

5664-456: The first prototype Trident I conducted the type's maiden flight; flown by test pilot Jacques Guignard, the aircraft used the entire length of the runway to get airborne, being powered only by its two 4 kN (900 lbf) Turbomeca Marboré turbojet engines. It was initially flown without any rocket engine installed, relying solely upon its turbojet engines instead to evaluate its low-speed handling. According to aviation historian Bill Gunston ,

5760-408: The flow field around the object includes both sub- and supersonic parts. The transonic period begins when first zones of M > 1 flow appear around the object. In case of an airfoil (such as an aircraft's wing), this typically happens above the wing. Supersonic flow can decelerate back to subsonic only in a normal shock; this typically happens before the trailing edge. (Fig.1a) As the speed increases,

5856-416: The formation of shock waves; instead, the tailplane controlled roll by moving in opposite directions. All three tail surfaces were all-moving, eliminating the requirement for separate elevators and rudders while preventing control lock-ups during high speeds. Suitably impressed with the design and its projected performance, SNCASO received a contract for two prototypes on 8 April 1951. On 2 March 1953,

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5952-512: The free stream Mach number is below this value. Meanwhile, the supersonic regime is usually used to talk about the set of Mach numbers for which linearised theory may be used, where for example the ( air ) flow is not chemically reacting, and where heat-transfer between air and vehicle may be reasonably neglected in calculations. Generally, NASA defines high hypersonic as any Mach number from 10 to 25, and re-entry speeds as anything greater than Mach 25. Aircraft operating in this regime include

6048-458: The fuselage. The design was unusual for more than just its mixed-propulsion arrangement. Instead of a conventional ejection seat , the entire nose section could be jettisoned. Particular attention had been dedicated to the control system to ensure it would be suitable throughout the transonic and supersonic stages of flight; while conventional ailerons were used when flown at slow speeds, these would be locked out of use at higher speeds to prevent

6144-490: The influence of compressibility in a similar manner at a given Mach number, regardless of other variables. As modeled in the International Standard Atmosphere , dry air at mean sea level , standard temperature of 15 °C (59 °F), the speed of sound is 340.3 meters per second (1,116.5 ft/s; 761.23 mph; 1,225.1 km/h; 661.49 kn). The speed of sound is not a constant; in

6240-653: The interceptor role until it received upgrades in the 1990s for ground attack. Both the fighter and the Phoenix missile were retired in 2006. The British Royal Air Force operated a supersonic day fighter, the English Electric Lightning , alongside the Gloster Javelin in the subsonic night/all-weather role . Efforts to replace the Javelin with a supersonic design under Operational Requirement F.155 came to naught. The UK operated its own, highly adapted version of

6336-598: The interceptor role. Day interceptors have been used in a defensive role since World War I , and are perhaps best known from major actions like the Battle of Britain , when the Supermarine Spitfire and Hawker Hurricane were part of a successful defensive strategy. However, dramatic improvements in both ground-based and airborne radar gave greater flexibility to existing fighters and few later designs were conceived as dedicated day interceptors. Exceptions include

6432-421: The jet engines alone would be used to return to base. Servanty persuaded the Air Force to fund a design study and a mockup on 7 July 1950. The rocket engine selected was based that used by the Matra M.04 missile . It was powered by a mixture of Furaline (C 13 H 12 N 2 O) and nitric acid (HNO 3 ); according to Pelt, the decision to use nitric acid as the oxidizing agent posed some challenges as it

6528-412: The medium, or it can be stationary while the medium flows along it, or they can both be moving, with different velocities : what matters is their relative velocity with respect to each other. The boundary can be the boundary of an object immersed in the medium, or of a channel such as a nozzle , diffuser or wind tunnel channelling the medium. As the Mach number is defined as the ratio of two speeds, it

6624-668: The only widely used examples designed after the 1960s being the Panavia Tornado ADV , Mikoyan MiG-25 , Mikoyan MiG-31 , and the Shenyang J-8 . The first interceptor squadrons were formed during World War I to defend London against attacks by Zeppelins and later against fixed-wing long-range bombers . Early units generally used aircraft withdrawn from front-line service, notably the Sopwith Pup . They were told about their target's location before take-off from

6720-436: The overall mission time, there were few ways to reduce this. During the Cold War in times of heightened tensions, quick reaction alert (QRA) aircraft were kept piloted, fully fueled and armed, with the engines running at idle on the runway ready to take off. The aircraft being kept topped up with fuel via hoses from underground fuel tanks. If a possible intruder was identified, the aircraft would be ready to take off as soon as

6816-510: The propulsion arrangement. During March 1951, the first ground tests of the rocket engine were performed; on 10 June 1952, the modified Espadon test bed performed its maiden flight . During its test programme, improved rocket engines were trialed and the aircraft became the first European aircraft to attain Mach 1 during level flight. Encouraged by the success of the Espadon, the Air Force issued

6912-567: The radar". By flying terrain masking low-altitude nap-of-the-earth flight profiles the effective range, and therefore reaction time, of ground-based radar was limited to at best the radar horizon . In the case of ground radar systems this can be countered by placing radar systems on mountain tops to extend the radar horizon, or through placing high performance radars in interceptors or in AWACS aircraft used to direct point defense interceptors. As capabilities continued to improve – especially through

7008-453: The ratio of flow velocity past a boundary to the local speed of sound . It is named after the Austrian physicist and philosopher Ernst Mach . M = u c , {\displaystyle \mathrm {M} ={\frac {u}{c}},} where: By definition, at Mach   1, the local flow velocity u is equal to the speed of sound. At Mach   0.65, u is 65% of

7104-427: The rebuilding of its military, particularly the French Air Force with the indigenous development of advanced military aircraft. In this respect, one area of high interest was the relatively new field of rocket-powered aircraft . According to aviation historian Michel van Pelt, French Air Force officials were against a pure rocket-powered fighter, akin to the wartime-era Messerschmitt Me 163 Komet , but instead favoured

7200-467: The remaining Trident I prototype were resumed, flown by test pilot Charles Goujon. On what would have been its sixth rocket-powered flight on 26 October, the rocket failed during take off and the aircraft was barely able to return to the runway and land safely. This incident graphically demonstrated that the Trident needed more power from its turbojets and the aircraft was grounded until more powerful 7.34 kN (1,654 lbf) Dassault MD.30 Viper engines,

7296-404: The role merged with that of the heavy air superiority fighter . The interceptor mission is, by its nature, a difficult one. Consider the desire to protect a single target from attack by long-range bombers. The bombers have the advantage of being able to select the parameters of the mission – attack vector, speed and altitude. This results in an enormous area from which the attack can originate. In

7392-527: The sea level value. The terms subsonic and supersonic are used to refer to speeds below and above the local speed of sound, and to particular ranges of Mach values. This occurs because of the presence of a transonic regime around flight (free stream) M = 1 where approximations of the Navier-Stokes equations used for subsonic design no longer apply; the simplest explanation is that the flow around an airframe locally begins to exceed M = 1 even though

7488-436: The single-engine Bell P-39 Airacobra and the twin-engine Lockheed P-38 Lightning . Both aircraft were successful during World War II in standard fighter roles, not specifically assigned to point defense against bombers. From 1946 to 1980 the United States maintained a dedicated Aerospace Defense Command , consisting primarily of dedicated interceptors. Many post-war designs were of limited performance, including designs like

7584-416: The speed of sound (subsonic), and, at Mach   1.35, u is 35% faster than the speed of sound (supersonic). The local speed of sound, and hence the Mach number, depends on the temperature of the surrounding gas. The Mach number is primarily used to determine the approximation with which a flow can be treated as an incompressible flow . The medium can be a gas or a liquid. The boundary can be travelling in

7680-463: The speed of sound is known, the Mach number at which an aircraft is flying can be calculated by M = u c {\displaystyle \mathrm {M} ={\frac {u}{c}}} where: and the speed of sound varies with the thermodynamic temperature as: c = γ ⋅ R ∗ ⋅ T , {\displaystyle c={\sqrt {\gamma \cdot R_{*}\cdot T}},} where: If

7776-779: The speed of sound is not known, Mach number may be determined by measuring the various air pressures (static and dynamic) and using the following formula that is derived from Bernoulli's equation for Mach numbers less than 1.0. Assuming air to be an ideal gas , the formula to compute Mach number in a subsonic compressible flow is: M = 2 γ − 1 [ ( q c p + 1 ) γ − 1 γ − 1 ] {\displaystyle \mathrm {M} ={\sqrt {{\frac {2}{\gamma -1}}\left[\left({\frac {q_{c}}{p}}+1\right)^{\frac {\gamma -1}{\gamma }}-1\right]}}\,} where: The formula to compute Mach number in

7872-405: The speed, the more narrow the cone; at just over M = 1 it is hardly a cone at all, but closer to a slightly concave plane. At fully supersonic speed, the shock wave starts to take its cone shape and flow is either completely supersonic, or (in case of a blunt object), only a very small subsonic flow area remains between the object's nose and the shock wave it creates ahead of itself. (In the case of

7968-425: The speed. The obvious result is that in order to accelerate a flow to supersonic, one needs a convergent-divergent nozzle, where the converging section accelerates the flow to sonic speeds, and the diverging section continues the acceleration. Such nozzles are called de Laval nozzles and in extreme cases they are able to reach hypersonic speeds (Mach 13 (15,900 km/h; 9,900 mph) at 20 °C). When

8064-399: The temperature increases so much over the shock that ionization and dissociation of gas molecules behind the shock wave begin. Such flows are called hypersonic. It is clear that any object travelling at hypersonic speeds will likewise be exposed to the same extreme temperatures as the gas behind the nose shock wave, and hence choice of heat-resistant materials becomes important. As a flow in

8160-486: The time it takes for the bombers to cross the distance from first detection to being on their targets, the interceptor must be able to start, take off, climb to altitude, maneuver for attack and then attack the bomber. A dedicated interceptor aircraft sacrifices the capabilities of the air superiority fighter and multirole fighter (i.e., countering enemy fighter aircraft in air combat manoeuvring ), by tuning its performance for either fast climbs or high speeds. The result

8256-647: The use of a more powerful rocket as a two-chamber 29.3 kN (6,600 lbf) SEPR 631 rocket replaced the SEPR 431. Other changes included the deletion of the ailerons, a smaller wing, an enlarged cockpit , the transfer of the speed brakes from the wings to the fuselage and the lengthening of the landing gear to accommodate a large air-to-air missile (AAM) beneath the fuselage. The first aircraft made its maiden flight on 19 July 1955, albeit only with its turbojets, and its first rocket-powered flight occurred on 21 December. The second prototype first flew on 4 January 1956, but

8352-420: The widespread introduction of the jet engine and the adoption of high speed, low level flight profiles, the time available between detection and interception dropped. Most advanced point defence interceptors combined with long-range radars were struggling to keep the reaction time down enough to be effective. Fixed times, like the time needed for the pilot to climb into the cockpit, became an increasing portion of

8448-437: The zone of M > 1 flow increases towards both leading and trailing edges. As M = 1 is reached and passed, the normal shock reaches the trailing edge and becomes a weak oblique shock: the flow decelerates over the shock, but remains supersonic. A normal shock is created ahead of the object, and the only subsonic zone in the flow field is a small area around the object's leading edge. (Fig.1b) When an aircraft exceeds Mach 1 (i.e.

8544-580: Was corrosive to both the airframe and engine. The combination of Furaline, which was relatively difficult to manufacture in comparison to conventional kerosene , and nitric acid functioned as a hypergolic propellant , not requiring any igniting agent. However, as manned rocket aircraft were an entirely unknown commodity within France, the Air Force decided to modify an existing aircraft, the Sud-Ouest Espadon , to serve as an aerial test bed to prove

8640-452: Was SNCASO with their own proposal, which was based upon their earlier design studies; their design was later designated as the SO.9000 Trident . The Trident was a fast-looking bullet -shaped aircraft, furnished with an aerodynamically clean fuselage and thin, straight wings in order to minimise drag . It was equipped with a narrow-track tricycle landing gear with the main wheels retracting into

8736-472: Was a prototype jet fighter developed during the 1950s. It never flew and was cancelled in 1960. The Canadian subsonic Avro Canada CF-100 Canuck served in numbers through 1950s. Its supersonic replacement, the CF-105 Arrow ("Avro Arrow"), was controversially cancelled in 1959. The Swedish Saab 35 Draken was specifically designed for intercepting aircraft passing Swedish airspace at high altitudes in

8832-544: Was designated for deployment of interceptors. The aircraft of the Soviet Air Defence Forces (PVO-S) differed from those of the Soviet Air Forces (VVS) in that they were by no means small or crudely simple, but huge and refined with large, sophisticated radars; they could not take off from grass, only concrete runways; they could not be disassembled and shipped back to a maintenance center in

8928-652: Was designed primarily as a stealth air superiority fighter. In the 1950s, the United States Navy led an unsuccessful F6D Missileer project. Later it launched the development of a large F-111B fleet air defense fighter, but this project was cancelled too. Finally, the role was assigned to the F-14 Tomcat , carrying AIM-54 Phoenix missiles. Like the USAF's F-15, the USN's F-14 was also designed primarily as an air superiority (fighter-to-fighter combat) and F-14s served

9024-402: Was destroyed three days later when the fuel pump to the turbojets failed and the engines flamed out . A third prototype had been built by SNCASO to develop a surface-to-air missile based on the Trident, but it was purchased by the Air Force to replace the destroyed aircraft and first flew on 30 March. On 16 February 1956, the first prototype reached a speed of Mach 1.7 while carrying a mockup of

9120-522: Was for interceptors as the Commonwealth and American air forces pounded German targets night and day. As the bombing effort grew, notably in early 1944, the Luftwaffe introduced a rocket-powered design, the Messerschmitt Me 163 Komet , in the very-short-range interceptor role. The engine allowed about 7 minutes of powered flight, but offered such tremendous performance that they could fly right by

9216-458: Was issued to SNCASO. In response, the firm designed the mixed-propulsion Trident, powered by a single SEPR rocket engine, which was augmented by wingtip -mounted turbojet engines, and the Air Force ordered two prototypes . The two SO.9000 Trident Is demonstrated the feasibility of the design concept despite the loss of one aircraft during flight testing and the Air Force ordered a batch of three prototype SO.9050 Trident II fighters in 1954, and

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