115-542: The V3E A-Darter (Agile Darter) is a modern short-range infrared homing ("heat seeking") air-to-air missile , featuring countermeasures resistance with a 180-degree look angle and 120-degrees per second track rate, developed by South Africa's Denel Dynamics (formerly Kentron) and Brazil's Mectron (now SIATT ), Avibras and Opto Eletrônica (acquired by AKAER ). It will equip the South African Air Force 's Saab JAS 39 Gripen C/D and BAE Hawk 120 , and
230-415: A forward looking infrared or similar cueing system. Heat-seekers are extremely effective: 90% of all United States air combat losses between 1984 and 2009 were caused by infrared-homing missiles. They are, however, subject to a number of simple countermeasures, most notably by dropping flares behind the target to provide false heat sources. That works only if the pilot is aware of the missile and deploys
345-403: A British rigid airship that first flew in 1916 and the twin 1930s-era U.S. Navy rigid airships USS Akron and USS Macon that were used as airborne aircraft carriers , and a similar form of thrust vectoring is also particularly valuable today for the control of modern non-rigid airships . In this use, most of the load is usually supported by buoyancy and vectored thrust is used to control
460-621: A Gripen in January 2012. Final testing included the use of high-speed target drones to simulate an aircraft by towing infrared targets at high speed. In December 2012, the Brazilian air force commissioned Denel to build a factory in São José dos Campos , close to Mectron, Avibras and Opto Eletrônica. In February 2015, Denel Dynamics signed an agreement with Marotta Controls for supply of the latter's MPACT pure air compression technology to cool
575-625: A better weapon than the Falcon: B models managed a 14% kill ratio, while the much longer-ranged D models managed 19%. Its performance and lower cost led the Air Force to adopt it as well. The first heat-seeker built outside the US was the UK's de Havilland Firestreak . Development began as OR.1056 Red Hawk , but this was considered too advanced, and in 1951 an amended concept was released as OR.1117 and given
690-673: A given aircraft to achieve TVFC can vary from one on a CTOL aircraft to a minimum of four in the case of STOVL aircraft. An example of 2D thrust vectoring is the Rolls-Royce Pegasus engine used in the Hawker Siddeley Harrier , as well as in the AV-8B Harrier II variant. Widespread use of thrust vectoring for enhanced maneuverability in Western production-model fighter aircraft didn't occur until
805-606: A large searchlight fitted with a filter to limit the output to the IR range. This provided enough light to see the target at short range, and Spanner Anlage was fitted to a small number of Messerschmitt Bf 110 and Dornier Do 17 night fighters . These proved largely useless in practice and the pilots complained that the target often only became visible at 200 metres (660 ft), at which point they would have seen it anyway. Only 15 were built and were removed as German airborne radar systems improved though 1942. AEG had been working with
920-399: A lesser extent. In missile literature originating from Russian sources, thrust vectoring is referred to as gas-dynamic steering or gas-dynamic control . Nominally, the line of action of the thrust vector of a rocket nozzle passes through the vehicle's centre of mass , generating zero net torque about the mass centre. It is possible to generate pitch and yaw moments by deflecting
1035-554: A low speed, the rocket motor's exhaust has a high enough speed to provide sufficient forces on the mechanical vanes. Thus, thrust vectoring can reduce a missile's minimum range. For example, anti-tank missiles such as the Eryx and the PARS 3 LR use thrust vectoring for this reason. Some other projectiles that use thrust-vectoring: Most currently operational vectored thrust aircraft use turbofans with rotating nozzles or vanes to deflect
1150-471: A missile airframe and considerable effort remained before an actual weapon would be ready for use. Nevertheless, a summer 1944 report to the German Air Ministry stated that these devices were far better developed than competing systems based on radar or acoustic methods. Aware of the advantages of passive IR homing, the research program started with a number of theoretical studies considering
1265-522: A more conventional hemispherical dome. The first test firing took place in 1955 and it entered service with the Royal Air Force in August 1958. The French R.510 project began later than Firestreak and entered experimental service in 1957, but was quickly replaced by a radar-homing version, the R.511. Neither was very effective and had short range on the order of 3 km. Both were replaced by
SECTION 10
#17327805317451380-619: A number of victories in the middle east and Vietnam. A major upgrade program for the Redeye started in 1967, as the Redeye II. Testing did not begin until 1975 and the first deliveries of the now renamed FIM-92 Stinger began in 1978. An improved rosette seeker was added to the B model in 1983, and several additional upgrades followed. Sent to the Soviet–Afghan War , they claimed a 79% success rate against Soviet helicopters, although this
1495-498: A position where the missile would be able to continue tracking even after launch. This problem also led to efforts to make new missiles that would hit their targets even if launched under these less-than-ideal positions. In the UK this led to the SRAAM project, which was ultimately the victim of continually changing requirements. Two US programmes, AIM-82 and AIM-95 Agile , met similar fates. New seeker designs began to appear during
1610-503: A practical detector. Nevertheless, it was used for some time by the US Navy as a secure communications system. In 1930 the introduction of the Ag–O–Cs ( silver – oxygen – cesium ) photomultiplier provided the first practical solution to the detection of IR, combining it with a layer of galena as the photocathode . Amplifying the signal emitted by the galena, the photomultiplier produced
1725-504: A side-by-side configuration. If such a craft is flown in a way where it enters a vortex ring state , one of the rotors will always enter slightly before the other, causing the aircraft to perform a drastic and unplanned roll. Thrust vectoring is also used as a control mechanism for airships . An early application was the British Army airship Delta , which first flew in 1912. It was later used on HMA (His Majesty's Airship) No. 9r ,
1840-569: A smoke trail, which means no visual warning for enemy aircraft. According to SAAF fighter pilots involved within the project, the A-Darter it is better than the IRIS-T in some respects. Infrared homing Infrared homing is a passive weapon guidance system which uses the infrared (IR) light emission from a target to track and follow it seamlessly. Missiles which use infrared seeking are often referred to as "heat-seekers" since infrared
1955-435: A streamlined design with low aerodynamic drag in a wingless airframe, ensuring ranges beyond those of traditional short-range missiles. It is fitted with a thrust vectoring control (TVC) system that allows for turning at up to 100 g and for a period of 8 seconds while the motor burns, after which the missile can still retain 50g of manoverability. The absence of aluminium powder in the motor propellent inhibits production of
2070-568: A supersonic version. At this stage the concept was for a defensive weapon fired rearward out of a long tube at the back end of bomber aircraft . In April 1949 the Firebird missile project was cancelled and MX-904 was redirected to be a forward-firing fighter weapon. The first test firings began in 1949, when it was given the designation AAM-A-2 (Air-to-air Missile, Air force, model 2) and the name Falcon. IR and semi-active radar homing (SARH) versions both entered service in 1956, and became known as
2185-657: A target behind the aircraft, sometimes called an "over-the-shoulder". Engage modes include Lock-On After Launch (LOAL) capability to engage targets outside its seeker's acquisition range, and Lock-On Before Launch (LOBL) capability where the target is identified and designated before launch. The two colour thermal imaging technology and a laser proximity fuse fitted on the missile provide multiple Electronic counter-countermeasures (ECCM) techniques with targeting algorithms including advanced spatial filtering techniques and velocity profiling. The A-Darter has four major sections: guidance section, warhead, control, and rocket motor. It uses
2300-447: A transparent plate with a sequence of opaque segments painted on them that was placed in front of the IR detector. The plate spins at a fixed rate, which causes the image of the target to be periodically interrupted, or chopped . The Hamburg system developed during the war is the simplest system, and easiest to understand. Its chopper was painted black on one half with the other half left transparent. For this description we consider
2415-429: A useful output that could be used for detection of hot objects at long ranges. This sparked developments in a number of nations, notably the UK and Germany where it was seen as a potential solution to the problem of detecting night bombers . In the UK, research was plodding, with even the main research team at Cavendish Labs expressing their desire to work on other projects, especially after it became clear that radar
SECTION 20
#17327805317452530-586: A vertically mounted, low-pressure shaft-driven remote fan, which is driven through a clutch during landing from the engine. Both the exhaust from this fan and the main engine's fan are deflected by thrust vectoring nozzles, to provide the appropriate combination of lift and propulsive thrust. It is not conceived for enhanced maneuverability in combat, only for VTOL operation, and the F-35A and F-35C do not use thrust vectoring at all. The Sukhoi Su-30MKI , produced by India under licence at Hindustan Aeronautics Limited ,
2645-581: A very desirable device. Kutzscher's team developed a system with the Eletroacustic Company of Kiel known as Hamburg , which was being readied for installation in the Blohm & Voss BV 143 glide bomb to produce an automated fire-and-forget anti-shipping missile. A more advanced version allowed the seeker to be directed off-axis by the bombardier in order to lock on to a target to the sides, without flying directly at it. However, this presented
2760-401: Is an afterburning supersonic nozzle where nozzle functions are throat area, exit area, pitch vectoring and yaw vectoring. These functions are controlled by four separate actuators. A simpler variant using only three actuators would not have independent exit area control. When TVFC is implemented to complement CAFC, agility and safety of the aircraft are maximized. Increased safety may occur in
2875-622: Is debated. The Soviets likewise improved their own versions, introducing the 9K34 Strela-3 in 1974, and the greatly improved dual-frequency 9K38 Igla in 1983, and Igla-S in 2004. The three main materials used in the infrared sensor are lead(II) sulfide (PbS), indium antimonide (InSb) and mercury cadmium telluride (HgCdTe). Older sensors tend to use PbS, newer sensors tend to use InSb or HgCdTe. All perform better when cooled, as they are both more sensitive and able to detect cooler objects. Early infrared seekers were most effective in detecting infrared radiation with shorter wavelengths, such as
2990-752: Is fixed, however a fluid is introduced into the exhaust flow from injectors mounted around the aft end of the missile. If the liquid is injected on only one side of the missile, it modifies that side of the exhaust plume, resulting in different thrust on that side thus an asymmetric net force on the missile. This was the control system used on the Minuteman II and the early SLBMs of the United States Navy . An effect similar to thrust vectoring can be produced with multiple vernier thrusters , small auxiliary combustion chambers which lack their own turbopumps and can gimbal on one axis. These were used on
3105-547: Is in active service with the Indian Air Force . The TVC makes the aircraft highly maneuverable, capable of near-zero airspeed at high angles of attack without stalling, and dynamic aerobatics at low speeds. The Su-30MKI is powered by two Al-31FP afterburning turbofans . The TVC nozzles of the MKI are mounted 32 degrees outward to longitudinal engine axis (i.e. in the horizontal plane) and can be deflected ±15 degrees in
3220-436: Is not required, instead, both signals can be extracted from a single photocell with the use of electrical delays or a second reference signal 90 degrees out of phase with the first. This system produces a signal that is sensitive to the angle around the clock face, the bearing , but not the angle between the target and the missile centerline, the angle off (or angle error ). This was not required for anti-ship missiles where
3335-411: Is obtained through deflection of the aircraft jets in some or all of the pitch, yaw and roll directions. In the extreme, deflection of the jets in yaw, pitch and roll creates desired forces and moments enabling complete directional control of the aircraft flight path without the implementation of the conventional aerodynamic flight controls (CAFC). TVFC can also be used to hold stationary flight in areas of
3450-502: Is only possible when the propulsion system is creating thrust; separate mechanisms are required for attitude and flight path control during other stages of flight. Thrust vectoring can be achieved by four basic means: Thrust vectoring for many liquid rockets is achieved by gimbaling the whole engine . This involves moving the entire combustion chamber and outer engine bell as on the Titan II 's twin first-stage motors, or even
3565-456: Is radiated strongly by hot bodies. Many objects such as people, vehicle engines and aircraft generate and emit heat and so are especially visible in the infrared wavelengths of light compared to objects in the background. Infrared seekers are passive devices, which, unlike radar , provide no indication that they are tracking a target. That makes them suitable for sneak attacks during visual encounters or over longer ranges when they are used with
A-Darter - Misplaced Pages Continue
3680-437: Is set too small the image from the target is too small to create a useful signal, while setting it too large makes it inaccurate. For this reason, linear scanners have inherent accuracy limitations. Additionally, the dual reciprocating motion is complex and mechanically unreliable, and generally two separate detectors have to be used. Most early seekers used so-called spin-scan , chopper or reticle seekers. These consisted of
3795-440: Is the ability of an aircraft , rocket or other vehicle to manipulate the direction of the thrust from its engine (s) or motor(s) to control the attitude or angular velocity of the vehicle. In rocketry and ballistic missiles that fly outside the atmosphere, aerodynamic control surfaces are ineffective, so thrust vectoring is the primary means of attitude control . Exhaust vanes and gimbaled engines were used in
3910-557: The AIM-4 Falcon after 1962. The Falcon was a complex system offering limited performance, especially due to its lack of a proximity fuse, and managed only a 9% kill ratio in 54 firings during Operation Rolling Thunder in the Vietnam War . However, this relatively low success rate must be appreciated in the context of all these kills representing direct hits, something that was not true of every kill by other American AAMs. In
4025-566: The AIM-9M Sidewinder and Stinger use compressed gas like argon to cool their sensors in order to lock onto the target at longer ranges and all aspects. (Some such as the AIM-9J and early-model R-60 used a peltier thermoelectric cooler ). The detector in early seekers was barely directional, accepting light from a very wide field of view (FOV), perhaps 100 degrees across or more. A target located anywhere within that FOV produces
4140-471: The AIM-9X Sidewinder , eschew flight control surfaces and instead use mechanical vanes to deflect rocket motor exhaust to one side. By using mechanical vanes to deflect the exhaust of the missile's rocket motor, a missile can steer itself even shortly after being launched (when the missile is moving slowly, before it has reached a high speed). This is because even though the missile is moving at
4255-556: The Atlas and R-7 missiles and are still used on the Soyuz rocket , which is descended from the R-7, but are seldom used on new designs due to their complexity and weight. These are distinct from reaction control system thrusters, which are fixed and independent rocket engines used for maneuvering in space. One of the earliest methods of thrust vectoring in rocket engines was to place vanes in
4370-587: The Brazilian Air Force 's A-1M AMX , Northrop F-5BR and Gripen E/F . It was expected to be in production before the end of 2015. As of November 2022, no combat capable missiles had been produced. Development of the A-Darter began in 1995, but the program suffered from inadequate funding and changes to the SAAF's requirements. Mectron, Avibras and Atech joined the program in 2006 after a three-year negotiation process with US$ 52 million invested by
4485-469: The Hamburg , an AC signal was generated that matched the rotational frequency of the disk. However, in this case the signal does not turn on and off with angle, but is constantly being triggered very rapidly. This creates a series of pulses that are smoothed out to produce a second AC signal at the same frequency as the test signal, but whose phase is controlled by the actual position of the target relative to
4600-495: The Space Shuttle Solid Rocket Booster (SRB), S-300P (SA-10) surface-to-air missile , UGM-27 Polaris nuclear ballistic missile and RT-23 (SS-24) ballistic missile and smaller battlefield weapons such as Swingfire . The principles of air thrust vectoring have been recently adapted to military sea applications in the form of fast water-jet steering that provide super-agility. Examples are
4715-426: The "Sun Tracker", was being developed as a possible guidance system for an intercontinental ballistic missile . Testing this system led to the 1948 Lake Mead Boeing B-29 crash . USAAF project MX-798 was awarded to Hughes Aircraft in 1946 for an infrared tracking missile. The design used a simple reticle seeker and an active system to control roll during flight. This was replaced the next year by MX-904, calling for
A-Darter - Misplaced Pages Continue
4830-581: The 1930s by Robert Goddard . For aircraft, the method was originally envisaged to provide upward vertical thrust as a means to give aircraft vertical ( VTOL ) or short ( STOL ) takeoff and landing ability. Subsequently, it was realized that using vectored thrust in combat situations enabled aircraft to perform various maneuvers not available to conventional-engined planes. To perform turns, aircraft that use no thrust vectoring must rely on aerodynamic control surfaces only, such as ailerons or elevator ; aircraft with vectoring must still use control surfaces, but to
4945-410: The 1960s. A new generation developed in the 1970s and the 1980s made great strides and significantly improved their lethality. The latest examples from the 1990s and on have the ability to attack targets out of their field of view (FOV) behind them and even to pick out vehicles on the ground. IR seekers are also the basis for many semi-automatic command to line of sight (SACLOS) weapons. In this use,
5060-480: The 1970s and led to a series of more advanced missiles. A major upgrade to the Sidewinder began, providing it with a seeker that was sensitive enough to track from any angle, giving the missile all aspect capability for the first time. This was combined with a new scanning pattern that helped reject confusing sources (like the sun reflecting off clouds) and improve the guidance towards the target. A small number of
5175-436: The 4.2 micrometre emissions of the carbon dioxide efflux of a jet engine . This made them useful primarily in tail-chase scenarios, where the exhaust was visible and the missile's approach was carrying it toward the aircraft as well. In combat these proved extremely ineffective as pilots attempted to make shots as soon as the seeker saw the target, launching at angles where the target's engines were quickly obscured or flew out of
5290-571: The A-Darter's infrared seeker. In March 2015 SAAF ordered 41 operational missiles, 21 trainer variants and 8 practice variants from Denel Dynamics. At this time deliveries were to be completed by October 2017. Production of the missiles has been delayed. Testing was finalised in November 2019. Due to liquidity problems affecting Denel and the resignation of key personnel, no combat capable missiles had been produced as of November 2022. As of October 2024 Denel has begun delivering practice missiles to
5405-495: The Block III version was put into production. The Soviets started development of two almost identical weapons in 1964, Strela-1 and Strela-2. Development of these proceeded much more smoothly, as the 9K32 Strela-2 entered service in 1968 after fewer years of development than the Redeye. Originally a competing design, the 9K31 Strela-1 was instead greatly increased in size for vehicle applications and entered service at around
5520-767: The Brazilian Government in the project, estimated to be worth US$ 130 million. In that same year, Denel announced that it would use the latest solid-state inertial measurement unit , the SiIMU02 from BAE Systems , for mid course range guidance. The Brazilian company Opto Eletrônica has partnered with Denel Dynamics in the development of the missile imaging infrared seeker for thermal guidance. Ground seeker tests were concluded in January 2010, while trajectory guidance and agility flight tests were performed in February 2010. Prototypes were sent to Saab AB to begin
5635-589: The R-73 problem was initially going to be the ASRAAM , a pan-European design that combined the performance of the R-73 with an imaging seeker. In a wide-ranging agreement, the US agreed to adopt ASRAAM for their new short-range missile, while the Europeans would adopt AMRAAM as their medium-range weapon. However, ASRAAM soon ran into intractable delays as each of the member countries decided a different performance metric
5750-721: The South African Air Force, with operational missiles being delivered in March or April of 2025 [1] The missile seeker can be slaved to the Helmet Mounted Display ( HMD ), allowing the pilot to track a target beyond the aircraft's radar scan envelope using the missile's high off-boresight capability, achieved by the pilot turning his head towards the target to lock-on, better known as "look and shoot". The missile can then be launched and can immediately pull extreme g-force to reverse its course to engage
5865-464: The ability to be fired at targets completely out of view of the seeker; after firing the missile would orient itself in the direction indicated by the launcher and then attempt to lock on. When combined with a helmet mounted sight , the missile could be cued and targeted without the launch aircraft first having to point itself at the target. This proved to offer significant advantages in combat, and caused great concern for Western forces. The solution to
SECTION 50
#17327805317455980-477: The aircraft and thus produce an ever-increasing signal while the aircraft is providing little or none. Additionally, as the missile approaches the target, smaller changes in relative angle are enough to move it out of this center null area and start causing control inputs again. With a bang-bang controller, such designs tend to begin to overreact during the last moments of the approach, causing large miss distances and demanding large warheads. A great improvement on
6095-542: The amateur group Copenhagen Suborbitals provide a modern example of jet vanes. Jet vanes must be made of a refractory material or actively cooled to prevent them from melting. Sapphire used solid copper vanes for copper's high heat capacity and thermal conductivity, and Nexo used graphite for its high melting point, but unless actively cooled, jet vanes will undergo significant erosion. This, combined with jet vanes' inefficiency, mostly precludes their use in new rockets. Some smaller sized atmospheric tactical missiles , such as
6210-410: The angle-off and feed that into the controls as well. This can be accomplished with the same disk and some work on the physical arrangement of the optics. Since the physical distance between the radial bars is larger at the outer position of the disk, the image of the target on the photocell is also larger, and thus has greater output. By arranging the optics so the signal is increasingly cut off closer to
6325-451: The basic spin-scan concept is the conical scanner or con-scan . In this arrangement, a fixed reticle is placed in front of the detector and both are positioned at the focus point of a small Cassegrain reflector telescope. The secondary mirror of the telescope is pointed slightly off-axis, and spins. This causes the image of the target to be spun around the reticle , instead of the reticle itself spinning. Consider an example system where
6440-409: The center of the disk, the resulting output signal varies in amplitude with the angle-off. However, it will also vary in amplitude as the missile approaches the target, so this is not a complete system by itself and some form of automatic gain control is often desired. Spin-scan systems can eliminate the signal from extended sources like sunlight reflecting from clouds or hot desert sand. To do this,
6555-478: The center of the operator's telescope. SACLOS systems of this sort have been used both for anti-tank missiles and surface-to-air missiles , as well as other roles. The infrared sensor package on the tip or head of a heat-seeking missile is known as the seeker head . The NATO brevity code for an air-to-air infrared-guided missile launch is Fox Two . The ability of certain substances to give off electrons when struck by infrared light had been discovered by
6670-401: The centerline it was. Other systems used a second scanning disk with radial slits to provide the same result but from a second output circuit. AEG developed a much more advanced system during the war, and this formed the basis of most post-war experiments. In this case, the disk was pattered with a series of opaque regions, often in a series of radial stripes forming a pizza-slice pattern. Like
6785-409: The centre, or a flexible seal made of a thermally resistant material, the latter generally requiring more torque and a higher power actuation system. The Trident C4 and D5 systems are controlled via hydraulically actuated nozzle. The STS SRBs used gimbaled nozzles. Another method of thrust vectoring used on solid propellant ballistic missiles is liquid injection, in which the rocket nozzle
6900-477: The code name Blue Jay . Designed as an anti-bomber weapon, the Blue Jay was larger, much heavier and flew faster than its US counterparts, but had about the same range. It had a more advanced seeker, using PbTe and cooled to −180 °C (−292.0 °F) by anhydrous ammonia to improve its performance. One distinguishing feature was its faceted nose cone, which was selected after it was found ice would build up on
7015-401: The control system and commands the missile to turn up. A second cell placed at the 3 o'clock position completes the system. In this case, the switching takes place not at the 9 and 3 o'clock positions, but 12 and 6 o'clock. Considering the same target, in this case, the waveform has just reached its maximum positive point at 12 o'clock when it is switched negative. Following this process around
SECTION 60
#17327805317457130-410: The countermeasures on time. The sophistication of modern seekers has rendered these countermeasures increasingly ineffective. The first IR devices were experimented with during World War II . During the war, German engineers were working on heat-seeking missiles and proximity fuses but did not have time to complete development before the war ended. Truly practical designs did not become possible until
7245-701: The deployment of the Lockheed Martin F-22 Raptor fifth-generation jet fighter in 2005, with its afterburning, 2D thrust-vectoring Pratt & Whitney F119 turbofan . While the Lockheed Martin F-35 Lightning II uses a conventional afterburning turbofan (Pratt & Whitney F135) to facilitate supersonic operation, its F-35B variant, developed for joint usage by the US Marine Corps , Royal Air Force , Royal Navy , and Italian Navy , also incorporates
7360-658: The designer was a patient in a mental hospital. Now being researched, Fluidic Thrust Vectoring (FTV) diverts thrust via secondary fluidic injections. Tests show that air forced into a jet engine exhaust stream can deflect thrust up to 15 degrees. Such nozzles are desirable for their lower mass and cost (up to 50% less), inertia (for faster, stronger control response), complexity (mechanically simpler, fewer or no moving parts or surfaces, less maintenance), and radar cross section for stealth . This will likely be used in many unmanned aerial vehicle (UAVs), and 6th generation fighter aircraft . Thrust-vectoring flight control (TVFC)
7475-401: The detector, or in the case of Madrid , two metal vanes were tilted to block off more or less of the signal. By comparing the time the flash was received to the location of the scanner at that time, the vertical and horizontal angle-off can be determined. However, these seekers also have the major disadvantage that their FOV is determined by the physical size of the slit (or opaque bar). If this
7590-410: The disk spinning clockwise as seen from the sensor; we will call the point in the rotation when the line between the dark and light halves is horizontal and the transparent side is on the top to be the 12 o'clock position. A photocell is positioned behind the disk at the 12 o'clock position. A target is located just above the missile. The sensor begins to see the target when the disk is at 9 o'clock, as
7705-401: The disk. By comparing the phase of the two signals, both the vertical and horizontal correction can be determined from a single signal. A great improvement was made as part of the Sidewinder program, feeding the output to the pilot's headset where it creates a sort of growling sound known as the missile tone that indicates that the target is visible to the seeker. In early systems this signal
7820-438: The emissions from the targets. This led to the practical discovery that the vast majority of the IR output from a piston-engine aircraft was between 3 and 4.5 micrometers. The exhaust was also a strong emitter, but cooled rapidly in the air so that it did not present a false tracking target. Studies were also made on atmospheric attenuation, which demonstrated that air is generally more transparent to IR than visible light, although
7935-520: The engine's exhaust stream. These exhaust vanes or jet vanes allow the thrust to be deflected without moving any parts of the engine, but reduce the rocket's efficiency. They have the benefit of allowing roll control with only a single engine, which nozzle gimbaling does not. The V-2 used graphite exhaust vanes and aerodynamic vanes, as did the Redstone , derived from the V-2. The Sapphire and Nexo rockets of
8050-468: The entire engine assembly including the related fuel and oxidizer pumps. The Saturn V and the Space Shuttle used gimbaled engines. A later method developed for solid propellant ballistic missiles achieves thrust vectoring by deflecting only the nozzle of the rocket using electric actuators or hydraulic cylinders . The nozzle is attached to the missile via a ball joint with a hole in
8165-433: The entire seeker assembly is mounted on a gimbal system that allows it to track the target through wide angles, and the angle between the seeker and the missile aircraft is used to produce guidance corrections. This gives rise the concepts of instantaneous field of view (IFOV) which is the angle the detector sees, and the overall field of view, also known as the tacking angle or off-boresight capability , which includes
8280-505: The event of malfunctioning CAFC as a result of battle damage. To implement TVFC a variety of nozzles both mechanical and fluidic may be applied. This includes convergent and convergent-divergent nozzles that may be fixed or geometrically variable. It also includes variable mechanisms within a fixed nozzle, such as rotating cascades and rotating exit vanes. Within these aircraft nozzles, the geometry itself may vary from two-dimensional (2-D) to axisymmetric or elliptic. The number of nozzles on
8395-462: The exhaust stream. This method allows designs to deflect thrust through as much as 90 degrees relative to the aircraft centreline. If an aircraft uses thrust vectoring for VTOL operations the engine must be sized for vertical lift, rather than normal flight, which results in a weight penalty. Afterburning (or Plenum Chamber Burning, PCB, in the bypass stream) is difficult to incorporate and is impractical for take-off and landing thrust vectoring, because
8510-499: The famous Indian polymath Jagadish Chandra Bose in 1901, who saw the effect in galena , known today as lead sulfide, PbS. There was little application at the time, and he allowed his 1904 patent to lapse. In 1917, Theodore Case , as part of his work on what became the Movietone sound system , discovered that a mix of thallium and sulfur was much more sensitive, but was highly unstable electrically and proved to be of little use as
8625-604: The first effective French design, the R.530 , in 1962. The Soviets introduced their first infrared homing missile, the Vympel K-13 in 1961, after reverse engineering a Sidewinder that stuck in the wing of a Chinese MiG-17 in 1958 during the Second Taiwan Strait Crisis . The K-13 was widely exported, and faced its cousin over Vietnam throughout the war. It proved even less reliable than the AIM-9B it
8740-402: The fixed signal is filtered out. A significant problem with the spin-scan system is that the signal when the target is near the center drops to zero. This is because even its small image covers several segments as they narrow at the center, producing a signal similar enough to an extended source that it is filtered out. This makes such seekers extremely sensitive to flares, which move away from
8855-414: The flight envelope where the main aerodynamic surfaces are stalled. TVFC includes control of STOVL aircraft during the hover and during the transition between hover and forward speeds below 50 knots where aerodynamic surfaces are ineffective. When vectored thrust control uses a single propelling jet, as with a single-engined aircraft, the ability to produce rolling moments may not be possible. An example
8970-403: The high degree of sensitivity required to lock onto the lower-level signals coming from the front and sides of an aircraft. Background heat from inside the sensor, or the aerodynamically heated sensor window, can overpower the weak signal entering the sensor from the target. ( CCDs in cameras have similar problems; they have much more "noise" at higher temperatures.) Modern all-aspect missiles like
9085-478: The integration of the missile to the Saab JAS 39 Gripen. Captive flight trials were concluded in March 2010. The first successful in-flight launch from a Gripen fighter took place on 17 June 2010. In March 2012, Denel Dynamics disclosed that the missile, which was to be ready for production by end of 2013, entered the qualification phase. Several testing firings at Denel's Overberg Test Range were carried out from
9200-416: The introduction of conical scanning and miniaturized vacuum tubes during the war. Anti-aircraft IR systems began in earnest in the late 1940s, but the electronics and the entire field of rocketry were so new that they required considerable development before the first examples entered service in the mid-1950s. The early examples had significant limitations and achieved very low success rates in combat during
9315-413: The location of the target by timing when the image disappeared (AEG) or reappeared (Kepka). The Kepka Madrid system had an instantaneous field of view (IFOV) of about 1.8 degrees and scanned a full 20 degree pattern. Combined with the movement of the entire seeker within the missile, it could track at angles as great as 100 degrees. Rheinmetall-Borsig and another team at AEG produced different variations on
9430-400: The main rocket thrust vector so that it does not pass through the mass centre. Because the line of action is generally oriented nearly parallel to the roll axis, roll control usually requires the use of two or more separately hinged nozzles or a separate system altogether, such as fins , or vanes in the exhaust plume of the rocket engine, deflecting the main thrust. Thrust vector control (TVC)
9545-418: The markings on the reticle. At this same instant, a spin-scan system would be producing a constant output in its center null. Flares will still be seen by the con-scan seeker and cause confusion, but they will no longer overwhelm the target signal as it does in the case of spin-scan when the flare leaves the null point. Thrust vectoring Thrust vectoring , also known as thrust vector control ( TVC ),
9660-555: The missile's field of view. Such seekers, which are most sensitive to the 3 to 5 micrometre range, are now called single-color seekers. This led to new seekers sensitive to both the exhaust as well as the longer 8 to 13 micrometer wavelength range, which is less absorbed by the atmosphere and thus allows dimmer sources like the fuselage itself to be detected. Such designs are known as "all-aspect" missiles. Modern seekers combine several detectors and are called two-color systems. All-aspect seekers also tend to require cooling to give them
9775-556: The motion of the aircraft. The first airship that used a control system based on pressurized air was Enrico Forlanini 's Omnia Dir in 1930s. A design for a jet incorporating thrust vectoring was submitted in 1949 to the British Air Ministry by Percy Walwyn; Walwyn's drawings are preserved at the National Aerospace Library at Farnborough. Official interest was curtailed when it was realised that
9890-460: The movement of the entire seeker assembly. Since the assembly cannot move instantly, a target moving rapidly across the missile's line of flight may be lost from the IFOV, which gives rise to the concept of a tracking rate , normally expressed in degrees per second. Some of the earliest German seekers used a linear-scan solution, where vertical and horizontal slits were moved back and forth in front of
10005-399: The negative voltage portion of its waveform, so the switch inverts this back to positive. When the disk reaches the 9 o'clock position the cell switches again, no longer inverting the signal, which is now entering its positive phase again. The resulting output from this cell is a series of half-sine waves, always positive. This signal is then smoothed out to produce a DC output, which is sent to
10120-474: The next year. Wally Schirra recalls visiting the lab and watching the seeker follow his cigarette. The missile was given the name Sidewinder after a local snake; the name had a second significance as the sidewinder is a pit viper and hunts by heat, and moves in an undulating pattern not unlike the missile. The Sidewinder entered service in 1957, and was widely used during the Vietnam war. It proved to be
10235-472: The period the target is visible to the sensor, the AC waveform is in the positive voltage period, varying from zero to its maximum and back to zero. When the target disappears, the sensor triggers a switch that inverts the output of the AC signal. For instance, when the disk reaches the 3 o'clock position and the target disappears, the switch is triggered. This is the same instant that the original AC waveform begins
10350-487: The presence of water vapour and carbon dioxide produced several sharp drops in transitivity. Finally, they also considered the issue of background sources of IR, including reflections off clouds and similar effects, concluding this was an issue due to the way it changed very strongly across the sky. This research suggested that an IR seeker could home on a three-engine bomber at 5 kilometres (3.1 mi) with an accuracy of about 1 ⁄ 10 degree, making an IR seeker
10465-428: The problem that when the bomb was first released it was traveling too slowly for the aerodynamic surfaces to easily control it, and the target sometimes slipped out from the view of the seeker. A stabilized platform was being developed to address this problem. The company also developed a working IR proximity fuse by placing additional detectors pointing radially outward from the missile centerline. which triggered when
10580-523: The resulting L models were rushed to the UK just prior to their engagement in the Falklands War , where they achieved an 82% kill ratio, and the misses were generally due to the target aircraft flying out of range. The Argentine aircraft, equipped with Sidewinder B and R.550 Magic , could only fire from the rear aspect, which the British pilots simply avoided by always flying directly at them. The L
10695-421: The reticle is modified by making one half of the plate be covered not with stripes but a 50% transmission color. The output from such a system is a sine wave for half of the rotation and a constant signal for the other half. The fixed output varies with the overall illumination of the sky. An extended target that spans several segments, like a cloud, will cause a fixed signal as well, and any signal that approximates
10810-410: The rotation causes a series of chopped-off positive and negative sine waves. When this is passed through the same smoothing system, the output is zero. This means the missile does not have to correct left or right. If the target were to move to the right, for instance, the signal would be increasingly positive from the smoother, indicating increasing corrections to the right. In practice a second photocell
10925-596: The same output signal. Since the goal of the seeker is to bring the target within the lethal radius of its warhead, the detector must be equipped with some system to narrow the FOV to a smaller angle. This is normally accomplished by placing the detector at the focal point of a telescope of some sort. This leads to a problem of conflicting performance requirements. As the FOV is reduced, the seeker becomes more accurate, and this also helps eliminate background sources which helps improve tracking. However, limiting it too much allows
11040-560: The same systems for use on tanks , and deployed a number of models through the war, with limited production of the FG 1250 beginning in 1943. This work culminated in the Zielgerät 1229 Vampir riflescope which was used with the StG 44 assault rifle for night use. The devices mentioned previously were all detectors, not seekers. They either produce a signal indicating the general direction of
11155-541: The same technologies have appeared in the Chinese PL-10 and Israeli Python-5 . Based on the same general principles as the original Sidewinder, in 1955 Convair began studies on a small man-portable missile ( MANPADS ) that would emerge as the FIM-43 Redeye . Entering testing in 1961, the preliminary design proved to have poor performance, and a number of major upgrades followed. It was not until 1968 that
11270-466: The same time. The UK began development of its Blowpipe in 1975, but placed the seeker on the launcher instead of the missile itself. The seeker sensed both the target and the missile and sent corrections to the missile via a radio link. These early weapons proved ineffective, with the Blowpipe failing in almost every combat use, while the Redeye fared somewhat better. The Strela-2 did better and claimed
11385-630: The same year as MX-798, 1946, William B. McLean began studies of a similar concept at the Naval Ordnance Test Station, today known as Naval Air Weapons Station China Lake . He spent three years simply considering various designs, which led to a considerably less complicated design than the Falcon. When his team had a design they believed would be workable, they began trying to fit it to the newly introduced Zuni 5-inch rocket . They presented it in 1951 and it became an official project
11500-403: The seeker is mounted on a trainable platform on the launcher and the operator keeps it pointed in the general direction of the target manually, often using a small telescope. The seeker does not track the target, but the missile, often aided by flares to provide a clean signal. The same guidance signals are generated and sent to the missile via thin wires or radio signals, guiding the missile into
11615-410: The seeker's mirror is tilted at 5 degrees, and the missile is tracking a target that is currently centered in front of the missile. As the mirror spins, it causes the image of the target to be reflected in the opposite direction, so in this case the image is moving in a circle 5 degrees away from the reticle's centerline. That means that even a centered target is creating a varying signal as it passes over
11730-405: The signal strength began to decrease, which it did when the missile passed the target. There was work on using a single sensor for both tasks instead of two separate ones. Other companies also picked up on the work by Eletroacustic and designed their own scanning methods. AEG and Kepka of Vienna used systems with two movable plates that continually scanned horizontally or vertically, and determined
11845-591: The spinning-disk system. In the post-war era, as the German developments became better known, a variety of research projects began to develop seekers based on the PbS sensor. These were combined with techniques developed during the war to improve accuracy of otherwise inherently inaccurate radar systems, especially the conical scanning system. One such system developed by the US Army Air Force (USAAF), known as
11960-407: The target is moving very slowly relative to the missile and the missile quickly aligns itself to the target. It was not appropriate for air-to-air use where the velocities were greater and smoother control motion was desired. In this case, the system was changed only slightly so the modulating disk was patterned in a cardioid which blanked out the signal for more or less time depending on how far from
12075-483: The target to move out of the FOV and be lost to the seeker. To be effective for guidance to the lethal radius, tracking angles of perhaps one degree are ideal, but to be able to continually track the target safely, FOVs on the order of 10 degrees or more are desired. This situation leads to the use of a number of designs that use a relatively wide FOV to allow easy tracking, and then process the received signal in some way to gain additional accuracy for guidance. Generally,
12190-470: The target, or in the case of later devices, an image. Guidance was entirely manual by an operator looking at the image. There were a number of efforts in Germany during the war to produce a true automatic seeker system, both for anti-aircraft use as well as against ships. These devices were still in development when the war ended; although some were ready for use, there had been no work on integrating them with
12305-414: The transparent portion of the chopper is aligned vertically at the target at 12 o'clock becomes visible. The sensor continues to see the target until the chopper reaches 3 o'clock. A signal generator produces an AC waveform that had the same frequency as the rotational rate of the disk. It is timed so the waveform reaches its maximum possible positive voltage point at the 12 o'clock position. Thus, during
12420-475: The vertical plane. This produces a corkscrew effect, greatly enhancing the turning capability of the aircraft. A few computerized studies add thrust vectoring to extant passenger airliners, like the Boeing 727 and 747, to prevent catastrophic failures, while the experimental X-48C may be jet-steered in the future. Examples of rockets and missiles which use thrust vectoring include both large systems such as
12535-553: The very hot exhaust can damage runway surfaces. Without afterburning it is hard to reach supersonic flight speeds. A PCB engine, the Bristol Siddeley BS100 , was cancelled in 1965. Tiltrotor aircraft vector thrust via rotating turboprop engine nacelles . The mechanical complexities of this design are quite troublesome, including twisting flexible internal components and driveshaft power transfer between engines. Most current tiltrotor designs feature two rotors in
12650-432: Was based on, with the guidance system and fuse suffering continual failure. As Vietnam revealed the terrible performance of existing missile designs, a number of efforts began to address them. In the US, minor upgrades to the Sidewinder were carried out as soon as possible, but more broadly pilots were taught proper engagement techniques so they would not fire as soon as they heard the missile tone, and would instead move to
12765-412: Was fed directly to the control surfaces, causing rapid flicking motions to bring the missile back into alignment, a control system known as "bang-bang". Bang-bang controls are extremely inefficient aerodynamically, especially as the target approaches the centerline and the controls continually flick back and forth with no real effect. This leads to the desire to either smooth out these outputs, or to measure
12880-595: Was going to be a better solution. Nevertheless, Frederick Lindemann , Winston Churchill 's favorite on the Tizard Committee , remained committed to IR and became increasingly obstructionist to the work of the Committee who were otherwise pressing for radar development. Eventually they dissolved the Committee and reformed, leaving Lindemann off the roster, and filling his position with well known radio expert Edward Victor Appleton . In Germany, radar research
12995-460: Was more important. The US eventually bowed out of the program, and instead adapted the new seekers developed for ASRAAM on yet another version of the Sidewinder, the AIM-9X. This so extends its lifetime that it will have been in service for almost a century when the current aircraft leave service. ASRAAM did, eventually, deliver a missile that has been adopted by a number of European forces and many of
13110-531: Was not given nearly the same level of support as in the UK, and competed with IR development throughout the 1930s. IR research was led primarily by Edgar Kutzscher at the University of Berlin working in concert with AEG . By 1940 they had successfully developed one solution; the Spanner Anlage (roughly "Peeping Tom system") consisting of a detector photomultiplier placed in front of the pilot, and
13225-578: Was so effective that aircraft hurried to add flare countermeasures, which led to another minor upgrade to the M model to better reject flares. The L and M models would go on to be the backbone of Western air forces through the end of the Cold War era. An even larger step was taken by the Soviets with their R-73 , which replaced the K-13 and others with a dramatically improved design. This missile introduced
#744255