In addition to rocket planes with two-component liquid-propellant jet engines, among the experimental aircraft of the X-series were aircraft with turbojet engines used as flying laboratories. This aircraft was the Douglas X-3 Stiletto. A monoplane with a straight thin trapezoidal wing of small aspect ratio had a very perfect shape from the point of view of aerodynamics, aimed at achieving maximum flight speed. Due to heavy loads, the wing was made of titanium and had a solid section. The fuselage of the aircraft was distinguished by a large aspect ratio, its length was almost three times the wingspan and a pointed nose, turning into a recessed lantern with sharp edges. In the event of an emergency, the pilot was ejected downward, which made rescue at low altitude impossible.
Douglas X-3 Stiletto
Since the design flight speed was to exceed 3 M, great attention was paid to thermal protection. The cockpit was equipped with air conditioning, and the parts of the fuselage that were exposed to the greatest heating were cooled by circulating kerosene, which required the installation of additional fuel pumps and the laying of auxiliary pipelines.
The Air Force command in the early 50s pinned great hopes on the Stiletto. On the basis of the experimental aircraft, it was planned to create a high-speed fighter-interceptor, which was to become the main means of intercepting Soviet long-range bombers in NORAD. Although soon after the start of testing, in October 1952, it was possible to exceed the speed of sound, these hopes were not realized. The capacity of two Westinghouse J-34-17 turbojet engines with an afterburner thrust of 21.8 kN was not enough to obtain design data. In addition, due to the low thrust-to-weight ratio and high specific load on the wing, the aircraft was strict in control and unsafe in operation. Very poor takeoff and landing characteristics (stall speed 325 km / h) made it unsuitable for use in combat units. The aircraft could only be operated by highly qualified test pilots, and extended runways were required for basing. As a result, the only built copy was used until 1956 as a flying aerodynamic laboratory. For this, the X-3 was equipped with various control and measuring and recording equipment with a total weight of more than 500 kg. To measure the pressure on the surfaces of the aircraft, there were more than 800 drainage holes, 180 electric tensometers measured air loads and voltages, and the temperature was controlled at 150 skin points. Although the Stiletto remained an experimental machine, the data obtained during the tests were used in the design of other supersonic aircraft.
In the late 1940s, with an increase in the flight speed of airplanes with swept wings, a deterioration in their take-off and landing characteristics was observed. In addition, the large sweep of the wing was not optimal for the cruising flight mode. Therefore, in different countries, the design of jet combat aircraft with variable geometry wings began.
After acquaintance with the captured German aircraft P.1101, captured at the Messerschmitt plant in Oberammergau, Bell specialists created in 1951 a prototype of the X-5 fighter, on which the wing sweep in flight could change in the range of 20 °, 40 ° and 60 °.
Bell X-5
Tests that took place at Edwards airbase from June 1951 to December 1958 demonstrated the possibility of creating a fighter with a variable geometry wing, but the X-5, created on the basis of an aircraft with obviously low speed data, did not meet modern requirements. It was not possible to exceed the speed of sound on the X-5. In total, two experimental aircraft were built, one of them crashed in 1953, burying the pilot Captain Ray Popson under its wreckage.
Not all experimental X-series aircraft tested in California were manned. In May 1953, an unmanned X-10 technology demonstrator, created by North American based on the SM-64 Navaho supersonic cruise missile, was delivered to Edwards AFB.
North American X-10
The X-10 supersonic drone was powered by two Westinghouse J-40 afterburners and retractable wheeled landing gear. The device was controlled by radio, and in cruising mode by an inertial navigation system. Commands for controls were generated by an on-board analog computer. For its time, the X-10 was one of the fastest and highest-altitude turbojet-powered aircraft. Its maximum speed exceeded 2 M, the flight altitude was 15000 m, and the supersonic flight range was over 1000 km. Of the 13 built, the very first X-10 survived. Most of the vehicles crashed during takeoff or landing, and engine explosions also occurred when the afterburner was turned on. Three more vehicles were used as supersonic air targets for testing air defense systems.
In the mid-60s, simultaneously with the tests of the strategic high-altitude high-speed reconnaissance aircraft SR-71 in California, a prototype of the North American XB-70A Valkyrie supersonic long-range bomber was tested. In total, two prototypes of the XB-70A were built, on June 8, 1966, one plane crashed as a result of a collision with an F-104A Starfighter.
XB-70A parked at Edwards AFB
"Valkyrie" was supposed to replace the B-52, which was too vulnerable for air defense systems and interceptors. During the tests, which lasted from September 1964 to February 1969, it was possible to reach a maximum speed of 3309 km / h, while the cruising speed was 3100 km / h. The ceiling is 23,000 meters, and the combat radius without refueling is almost 7,000 km. A bomber with such high flight performance in the 70s had a good chance of breaking through the Soviet air defense system. But in the end, the Valkyrie project was buried. Land-based silo ballistic missiles of the Minuteman family and Trident SLBMs had better survivability in the event of a surprise attack and were cheaper to manufacture and maintain.
In addition to research aimed at improving the flight and combat characteristics of aircraft in service, at Edwards airbase in the 80s, aircraft were tested using atypical aerodynamic schemes. Including work on the creation of a prototype of a promising fighter with a forward-swept wing. The use of such a wing shape theoretically makes it possible to significantly increase maneuverability and improve flight performance. The developers hoped that in combination with a computerized control system, this would make it possible to achieve an increase in the permissible angle of attack and angular rate of turn, a decrease in drag and an improvement in the layout of the aircraft. Due to the absence of stalling of the air flow from the wing tips, due to the displacement of the flow to the wing root, it becomes possible to improve flight data. A serious advantage of such a scheme is a more even distribution of lift over the wingspan, which simplifies the calculation and contributes to an increase in aerodynamic quality and controllability.
In December 1984, an experimental Kh-29A aircraft, built according to the "canard" design with an all-turning front horizontal tail, and with a forward swept wing, took off for the first time. This machine, designed by the Northrop Grumman corporation using elements of the F-5A (cockpit and front fuselage), F-16 (middle fuselage, engine mount), F / A-18 (engine) contained a lot of innovations. To increase strength and reduce weight, the most modern composites and alloys at that time were used in the manufacture of the wing. For the statically unstable X-29A aircraft, in addition to a negative sweep (-30 °) wing, center section and vertical tail, created from scratch, an original digital fly-by-wire system was used, which provided a minimum balancing resistance in all flight modes. To generate control commands, three analog computers were used, while their results were compared before the signal was transmitted to the executive part. This made it possible to identify errors in control commands and to carry out the necessary duplication. The movement of the steering surfaces using the above system took place depending on the flight speed and angle of attack. A failure in the digital control system would inevitably lead to a loss of control over the aircraft, while gliding flight was impossible.
But, despite all the fears, the tests were successful, and a year after the first flight, the sound barrier was exceeded. In general, the tests confirmed the design characteristics. But at first, test pilot Chuck Sewell was not satisfied with the very sluggish "bombing" reaction of the rudders to the movement of the control stick. This drawback was eliminated after the software of the control computers was improved.
Tests of the first copy of the Kh-29A continued until December 1988. According to the program drawn up by the Air Force, the aircraft passed tests to assess the maneuverability and feasibility of further developing a fighter of a similar scheme. In total, the first experimental specimen performed 254 flights, which indicates a fairly high test intensity.
The second copy of the Kh-29A
The second plane, the Kh-29A, took off in May 1989. This instance was distinguished by controls, additional sensors of the angle of attack and a variable thrust vector, which gave an increase in maneuverability.
In general, tests have confirmed that a negative sweep wing in combination with a fly-by-wire control system can significantly increase the maneuverability of a fighter. But at the same time, disadvantages were also noted, such as: the difficulty of achieving supersonic cruising flight speed, the increased sensitivity of the wing to loads and large bending moments at the wing root, the difficulty of selecting the shape of the articulation of the wing with the fuselage, the unfavorable effect of the wing on the tail, the possibility of dangerous vibrations. By the early 90s, with the advent of highly maneuverable melee missiles and medium-range missiles with an active radar seeker, the US military began to be skeptical about the need to create a highly specialized highly maneuverable fighter designed for dog fights. More attention was paid to reducing radar and thermal signature, improving the characteristics of radar and the ability to exchange information with other fighters. In addition, as mentioned, the forward-swept wing was not optimal for supersonic cruising speed. As a result, the United States refused to design a serial fighter with a wing shape similar to the Kh-29A.
Satellite image of Google Earth: an aircraft memorial at the northern end of Edwards AFB
The flights of the second instance of the Kh-29A continued until the end of September 1991; in total, this machine took off 120 times. In 1987, the first copy was transferred to the National Museum of the US Air Force, and the second X-29 was stored at Edwards AFB for about 15 years, after which it was installed in a memorial exhibit along with other aircraft that were tested here.
A notable event in the history of Edwards AFB was the test of the ASM-135 ASAT anti-satellite missile (eng. Air-based anti-satellite multi-stage missile - Anti-satellite multistage airborne missile). The carrier of this two-stage solid-propellant rocket with a cooled IR seeker and a kinetic warhead was a specially modified F-15A fighter.
F-15A fighter with ASM-135 ASAT missile launcher
After the appearance of reconnaissance satellites in the USSR and the deployment of a space tracking system for the American fleet, work began in the United States to create countermeasures. The interceptor, armed with the ASM-135 ASAT missile launcher, could destroy space objects at an altitude of more than 500 km. At the same time, the developer Vought announced the possibility of intercepting at an altitude of up to 1000 km. A total of five test launches of ASM-135 are known. In most cases, aiming was carried out on bright stars. The only successful defeat of a real target took place on September 13, 1985, when a faulty American P78-1 Solwind satellite was destroyed by a direct hit.
Launch of ASM-135 ASAT SD
Later, after the adoption of the anti-satellite system into service, it was planned to equip specially created "space" squadrons of F-15C fighters with ASM-135 ASAT missiles and introduce these missiles into the ammunition load of the F-14 heavy carrier-based fighters. In addition to intercepting satellites, an improved version of the anti-missile was to be used in the American missile defense system. Since fighters armed with anti-missile missiles deployed on the continental United States could destroy only 25% of Soviet satellites in low orbits, the Americans planned to create interceptor airfields in New Zealand and the Falkland Islands. However, the beginning "detente" in US-Soviet relations put an end to these plans. It is possible that there was a secret agreement between the leadership of the United States and the USSR on the refusal to develop this type of weapon.
Edwards Air Force Base is known not only for defense research and testing of new types of combat aircraft. On December 14, 1986, the Rutan Model 76 Voyager launched from a 4600-meter runway. This aircraft, created under the direction of Burt Ruthan, is specially designed to achieve record range and duration of flight.
Record aircraft Rutan Model 76 Voyager
The aircraft is powered by two piston engines 110 and 130 hp. with a wingspan of 33 meters, it had a "dry" weight of 1020.6 kg and could take on board 3181 kg of fuel. During the record flight, the Voyager was piloted by the designer's older brother Dick Rutan and Gina Yeager, who worked as a test pilot for the Rutan company. On December 23, after spending 9 days, 3 minutes and 44 seconds in the air and covering 42,432 km, Voyager landed safely at Edwards AFB.
At the very end of 1989, the first copy of the Northrop B-2 Spirit stealth bomber arrived at Edwards AFB for testing. Unlike the absolutely "black" F-117, whose very existence has not been officially confirmed for a long time, the B-2 was presented to the general public even before the first flight. It was impossible to hide the fact of creating a sufficiently large strategic bomber, although unprecedented secrecy measures were taken during its design and construction of the first instance. The aircraft, made according to the "flying wing" scheme, outwardly bore a significant resemblance to the unused YB-35 and YB-49 bombers, which were also designed by Northrop. It is symbolic that during the tests of the YB-49, Captain Glen Edwards died, after whose name the airbase was named, where the B-2 bomber was tested 40 years later.
B-2 during the first flight over California
The B-2A was put into service in 1997, and the first bomber was transferred to the 509th Bomber Wing in 1993. Currently, this wing at Whiteman AFB has 19 bombers. Another aircraft is permanently located at Edwards AFB, and the B-2, named "Spirit of Kansas", crashed on February 23, 2008 during takeoff from Andersen AFB in Guam. The only stealth bomber available in California is used in various tests and regularly participates in demonstration flights during air shows held at Edwards AFB.
B-2A on the runway of Edwards airbase
It was on this machine that various innovations were tested, which were subsequently introduced on the combat bombers of the 509th air wing. But unlike the B-1B and B-52H airbases, the B-2A bomber is almost always hidden from prying eyes in one of the hangars, at least it was not possible to find it on commercial satellite images.
The next experimental manned vehicle "X-series", passing tests at Edwards after the X-29A, was the X-31A. It was a joint project between Rockwell and Messerschmitt-Bölkow-Blohm. The purpose of this project was to study the possibility of creating a light super-maneuverable fighter. Externally, the X-31A was in many ways similar to the European EF-2000 fighter, but it used parts from the F-5, F-16 and F / A-18. In order to reduce the takeoff weight, only the most necessary equipment was mounted on the aircraft. To change the thrust vector of the engine, a design of three deflector swing flaps installed behind the afterburner cut was used. Flaps made of heat-resistant carbon fiber material could deflect the gas jet within 10 ° in any plane.
X-31A
After factory tests at Pamdale Airfield, both built X-31As were transferred to Edwards AFB to use the excellent test infrastructure available here.
During the tests, the Kh-31A demonstrated excellent maneuverability. In September 1992, the aircraft was brought to a unique mode, a stable flight was carried out at a pitch angle of 70 °. The experienced fighter turned almost in one place almost 360 °. For the first time in the United States, practical confirmation of the possibility of orienting a fighter to a target without changing its flight path was obtained. The Air Force specialists were convinced that a fighter with a thrust vector change system would be able to take an advantageous position for a melee attack earlier than a conventional aircraft. Computer analysis showed that such a fighter, when launching missiles outside the line of sight, also has significant advantages, since it is able to take a combat position faster than the enemy. In addition, a super-maneuverable combat aircraft is more successful in evading missiles launched at it.
In 1993, testing of the Kh-31A began in test air battles with the F / A-18 carrier-based fighter. In 9 out of 10 test air battles, the Kh-31A managed to win upwards. To assess the results of air fights, special video recording equipment was installed on the fighters. In January 1995, due to a control system failure, one Kh-31A crashed, but by that time the test results were beyond doubt. Experts from the US Air Force Flight Test Center and Rockwell Company performed a huge amount of work. In total, two experimental aircraft made 560 flights, having flown more than 600 hours in 4.5 years. According to a number of aviation experts, the Kh-31A was late. Had he appeared earlier, the developments obtained during his tests could have been practically implemented in the creation of the F-22A and Eurofighter Typhoon fighters.
In the 90s, prototypes of the 5th generation fighters YF-22A and YF-23A were tested in California. According to the results of tests, preference was given to the YF-22A, which went into series under the designation Lockheed Martin F-22 Raptor.
Its rival YF-23A flew a little faster and was less visible on radar screens, but the Raptor proved to be stronger in close air combat, which eventually tipped the scales in its favor. The F-22A heavy fighter with elements of radar signature reduction technology and flat, vertically deflected engine nozzles became the first 5th generation fighter in the world to be adopted. In this machine, low radar signature and high situational awareness of the pilot are combined with good maneuverability and supersonic cruising flight speed. Experts note the rather high data of the AN / APG-77 airborne radar with AFAR. The F-22A's radar, often referred to as "mini AWACS", provides a 120 ° field of view and can detect a target with a RCS of 1 m² at a range of 240 km. In addition to air, it is possible to track moving ground targets. In 2007, during tests at Edwards Air Force Base, the F-22A radar was tested as a wireless system for transmitting and receiving data, at a speed of 548 megabits per second. The fighter also has an AN / ALR-94 passive radar detector, which consists of receiving equipment for detecting radar radiation and a computer complex that determines the characteristics and direction to the signal source. More than 30 passive radar antennas are located on the fuselage and aircraft planes. The AN / AAR-56 system is responsible for the timely detection of approaching air-to-air and surface-to-air missiles. Six infrared and ultraviolet sensors monitor the entire area around the aircraft. The analysis of data coming from the radar and passive systems is carried out by two computers with a productivity of 10.5 billion operations per second.
Although the first flight of the YF-22A prototype took place on September 29, 1990, due to the great complexity of the design and problems with fine-tuning the onboard systems, the first F-22A reached operational readiness in December 2005. On production vehicles, in order to increase the maximum speed and reduce radar signature, the shape and thickness of the wing have been changed, the cockpit canopy has been shifted forward to obtain a better view, and the air intakes back.
Initially, the F-22A, intended to counter the Soviet Su-27 and MiG-29, was planned to be built in an amount of at least 600 copies. However, after the start of deliveries to combat squadrons, the number of vehicles in the proposed series was cut to 380 units. In 2008, the procurement plan was reduced to 188 fighters, but due to excessive cost, this figure was not achieved. In 2011, after the construction of 187 serial aircraft, production was discontinued. The cost of one Raptor, excluding R&D, in 2005 was more than $ 142 million, which is too expensive even by American standards. As a result, instead of the "golden" F-22A, it was decided to massively build the cheaper F-35 fighter, even if it did not have such outstanding characteristics. In the US Air Force, the few F-22As are considered "silver bullets", that is, fighters of a special reserve, capable of withstanding any enemy, which should be used in exceptional cases. The infliction of air strikes with guided aerial bombs from a great height on the positions of Islamists in the Middle East can be considered a kind of baptism of fire of the Raptor, although much cheaper combat aircraft could cope with this just as well.
Satellite image of Google Earth: F-22A parked at Edwards AFB
There are currently several F-22As at the airbase. They are used to test weapon systems and various innovations that are subsequently introduced to combat fighters. According to the Pentagon's plans, in 2017-2020, the F-22A should be upgraded to the Increment 3.2B version. Thanks to this, the Raptors will receive new types of aviation weapons and highly efficient electronic warfare equipment, comparable in their capabilities to that installed on the EA-18G Growler electronic warfare aircraft. It is planned to spend up to $ 16 billion on the modernization of the existing F-22A fleet.
Back in the 80s, after the launch of the SDI program by Ronald Reagan, research was carried out in the field of airborne combat lasers at Edwards AFB. However, the technological capabilities of that time made it possible to create only a “technology demonstrator”. With the help of a CO ² laser with a power of 0.5 MW installed on board the NKC-135A (a converted KS-135A tanker aircraft), it was possible to shoot down a drone and five AIM-9 Sidewinder missiles from a distance of several kilometers.
NKC-135A
They remembered about combat laser platforms in 1991, when the American MIM-104 Patriot air defense system demonstrated insufficiently good effectiveness against the Iraqi OTR R-17E and Al-Hussein. The developers were tasked with creating an aviation laser complex to combat short-range ballistic missiles in the theater of operations. It was assumed that heavy aircraft with combat lasers, flying at an altitude of up to 12,000 m, would be on alert at a distance of up to 150 km from the zone of probable launches. At the same time, they should be covered by escort fighters and electronic warfare aircraft. This time, a much more payload wide-body Boeing 747-400F was chosen as the carrier of the combat laser. Externally, the laser platform, designated YAL-1A, differed from the civilian airliner in the bow, where a rotating turret with the main mirror of the combat laser and numerous optical systems was mounted.
YAL-1A
According to information provided by the US military, a megawatt laser was installed on the YAL-1A plane, working on liquid oxygen and fine powdered iodine. In addition to the main combat laser, there were also a number of auxiliary laser systems on board for measuring distance, target designation and target tracking.
Tests of the air-launched anti-missile system began in March 2007. Although the creation of an aviation laser platform was officially announced in advance, during the test cycle, the YAL-1A was located in an area isolated from the main part of the air base with its own runway and specially guarded perimeter. This isolated area, known as Edwards Af Aux North Base, is located about 5 km north of the main facilities of the airbase, the extreme point of which is the section dedicated to serving the space shuttles. The command explained such safety measures by the use of toxic and explosive chemical reagents during the tests of the YAL-1A, which in the event of an accident could lead to a large number of casualties and damage the main facilities of the base. But, most likely, the main motive for placing the "flying laser cannon" behind the fence was to ensure the necessary secrecy. In the past, the northern isolated strip, where there are also large hangars and all the necessary infrastructure, was used to conduct secret tests of promising air-launched cruise missiles launched from the B-52H bomber.
During the air tests of the combat laser, it was possible to destroy several targets imitating tactical ballistic and cruise missiles. With the help of a laser aircraft cannon, it was also supposed to blind reconnaissance satellites, but it never came to real tests. But, having evaluated all the factors, the experts came to the conclusion that in real conditions the effectiveness of the system will be low, and the YAL-1A aircraft itself is extremely vulnerable to enemy fighters and modern long-range anti-aircraft systems. The fight against ballistic and aerodynamic targets turned out to be possible only at high altitudes, where the concentration of dust and water vapor in the atmosphere is minimal. Due to the excessive cost and dubious efficiency, it was decided to abandon the development of the air laser interceptor program, and after spending $ 5 billion, an experienced YAL-1A in 2012 was sent to the storage base in Davis-Montan.
