Battle of technology: Stealth + AWACS vs Super-maneuverability + EW
Introduction
The military doctrines of Russia and the NATO countries as a mandatory stage of hostilities provide for the achievement of superiority of their aviation in airspace over enemy territory - the so-called air supremacy. A typical example is the largest military conflict since World War II - the Iraq war of 1990-1991, in which 1,5 million troops and 3000 aircraft and helicopters were involved on both sides.
As a prerequisite for the start of the ground phase of the operation, the coalition forces were tasked with winning air superiority, including neutralizing Iraq’s air defense system. To accomplish this task, the latest at that time F-117 Nighthawk aircraft, created using the Stealth technology, were used together with the E-3 Sentry long-range radar detection and control aircraft using AWACS technology. F-117 in the dark participated in the decommissioning of command posts, communications centers and radar air defense systems.
A similar scenario of the outbreak of hostilities was repeated by NATO aircraft eight years later during the war in Yugoslavia. Using its technological advantage in the form of a Stealth + AWACS bundle once again helped the coalition forces suppress the enemy’s air defense system and gain air superiority. However, this time the F-117 aircraft, which are no longer a novelty, suffered losses - one of them was shot down, and the second after being hit by a ground-to-air missile was able to return to the base, but was written off due to injuries.
The military-technical policy of the NATO countries provides for the rearmament of tactical aviation with Stealth aircraft type F-35 Lightning II and airplanes with Stealth elements such as Dassault Rafale and Eurofighter Typhoon, as well as an increase in the AWACS aircraft fleet such as E-3 Sentry and E-737-700 Peace Eagle. In addition to these, the F-22 Raptor fighters designed to gain air supremacy are limited in number in the United States Air Force.
The experience of the participation of the Military Space Forces of Russia in local military conflicts in Georgia and Syria suggests a different approach to the choice of technologies to ensure air supremacy. Despite the adoption of the DRLOU A-50 domestic aircraft and the continued development of the promising unobtrusive T-50 fighter, the main emphasis is on the development of aviation electronic warfare equipment and the production of Su-35 fighter jets built according to the technology that ensures super-maneuverability in air combat.
Stealth technology
The first aircraft in the design of which the technology of stealth in the radio range was implemented is the American subsonic aircraft F-117, put into service in the 1983 year. Despite the presence of the letter F (fighter) in the title, by its flight capabilities and actual use it is a typical strike aircraft. Therefore, the F-117 could fight for air superiority only at long and medium distances using air-to-air missiles or by suppressing air defense systems, which he did.
The implementation of Stealth technology in its design is based on the following solutions:
- the airframe consists of a set of faceted surfaces reflecting the probing radio signal in the direction opposite to the direction of the radar;
- airframe elements are interconnected without the formation of angles in 90 degrees (the so-called corner reflectors), the vertical tail is V-shaped, there is no horizontal tail;
- connectors on the airframe surface are made with jagged edges, scattering the radio signal in different directions;
- the airframe trim includes cellular radio absorbing panels with a thickness of approximately 10 centimeters;
- a radar absorbing coating is additionally applied to the surface of the airframe;
- in order to exclude radio signal re-reflection from the internal equipment of the pilot's cabin and pilot's helmet, a metallized coating is applied to the cabin's glazing;
- the blades of the low-pressure compressors of the turbofan engines are shielded by grids installed on the air inlet;
- the propulsion system consists of two relatively low-power turbofan engines with reduced thermal emission;
- the blades of low-pressure turbine turbofan engines are shielded by the narrowing of the nozzle, the flat shape of which ensures a reduction in the thermal visibility of the jet due to its intensive mixing with the ambient air;
- aviation weapons (bombs and missiles) are placed on the inner suspension;
- radar, radio altimeter and “friend-foe” radio responder were excluded from on-board electronic equipment;
- the radio station in a combat situation only works at the reception.
Piloting the F-117 at night is done using thermal imagers and laser rangefinders / altimeters, which are part of two optical radar systems located above and below the fuselage.
Features of the implementation of Stealth technology imposes significant restrictions on the flight-tactical characteristics of the F-117. The faceted shape of the airframe reduces the aerodynamic quality of the aircraft to 4 units, making it impossible to conduct close combat with fighters. Due to the pressure loss in the air path of the engines (air intake grilles and flat nozzles), the F-117 has a lower thrust-to-weight ratio and range. The work of the radio station only at the reception determines the strictly individual nature of the combat missions. The exclusion of the “friend or foe” radio response from the avionics of the airborne unit makes it necessary to use the plane only if there are no miles in the air of friendly planes within the 100 radius. The abandonment of the airborne radar leads to the limitation of piloting weather conditions at the level of aircraft of the Second World War.
However, the reduction in F-117 radio objectivity was not ensured from all directions, the need to ensure a given level of lift caused the use of flat bottom surfaces of the wing and fuselage, with EPR from the lower hemisphere was sufficient to detect an aircraft with more than 30 km with meter radars and 15 km with centimeters. Attempts at piloting the F-117 at low altitudes led to its discovery by thermal imaging systems of the air defense system and MANPADS almost immediately after the exit due to radio horizon.
The aircraft was decommissioned after one vehicle was shot down and another was damaged in Yugoslavia using the Soviet Pechora S-125M air defense missile system, as well as taking into account the mass equipment of fighters with optical-location stations with a detection range of up to 50 kilometers in the forward hemisphere and 100 kilometers rear hemisphere.
The accumulated experience in the production and combat use of the F-117 allowed the US Air Force to formulate requirements for the development of a different type of aircraft, originally intended to achieve superiority in the air and at the same time carried out using Stealth technology. Designed in accordance with these requirements, the F-22 fighter (adopted in 2001 year) is a compromise between the excellent flight performance of the F-15 aerodynamic prototype and the level of stealthiness of its technological F-117 prototype.
The aerodynamic quality of the F-22 at the level of 10 units is ensured by the rejection of faceted glider forms. Supersonic speed is achieved by the use of engines that ensure the thrust-weight of the aircraft at the level of its weight. Increased maneuverability obtained by controlling the thrust vector of the engines in the vertical plane.
Stealth technology in F-22 is implemented by eliminating the articulation of airframe elements at right angles, using radar absorbing airframe surface and radar absorbing honeycomb in the toe of the wing, jagged edges of connectors, metallizing the cockpit canopy, using radar-blockers installed in front of the compressors and after the turbine turbine engines, as well as by placing all aircraft armament on the internal suspension. In contrast to the F-117, the F-22 avionics included a radar, radio altimeter and a “friend-foe” radio transponder. The radio station in a combat situation works both on reception and on data transmission.
The F-22 radio-visibility is reduced due to the special operating mode of the on-board radar - the so-called LPI (low probability of intercept), low probability of interception - noise-like radiation of reduced power with a floating frequency, frequency and polarization of the radio signal (the so-called complex discrete-coded signal).
Radio communication in a group of aircraft is carried out using directional antennas.
An additional on-board radio-electronic equipment is the radar radiation warning system AN / ALR-94, which includes several receivers distributed over the airframe.
As part of the BREM is no OLS, instead it uses the system AN / AAR-56 of several infrared sensors distributed over the surface of the airframe. Due to the absence of a laser rangefinder, this system is able to determine only the direction to the source of thermal radiation.
The attempt to combine the properties of a maneuverable fighter with the Stealth technology in F-22 led to an increase in its cost to 411 million US dollars (including R & D), which caused the refusal to build F-22 after the production of 187 production machines. Because of its high cost, the aircraft was not used in local conflicts as a means of suppressing air defense or to gain air superiority.
In this regard, the United States and other NATO countries (with the exception of Germany and France) chose a different, budget version of the Stealth-powered single-engine American aircraft, F-35, as a promising aircraft for gaining air supremacy. The machine is available in three versions at once: ground-based (basic version), deck-based (with an increased wingspan and a reinforced chassis) and vertical take-off and landing (with an additional fan and a rotatable engine nozzle). F-35 is planned to replace most NATO tactical aircraft: the F-15 Eagle, the F-16 Fighting Falcon, the F / A-18 Hornet and the AV-8 Harrier II.
As of the beginning of 2016, the 174 F-35 has been produced. The total number of aircraft planned for construction is estimated at 3000 units at a cost of one from 256 million dollars in the 2014 year to 120 million US dollars in the 2020 year. To date, all released F-35 are in trial operation, the combat readiness of the first of them is planned to be provided starting from the current year.
F-35, despite the letter F in the title, is a strike aircraft: its maximum take-off weight reaches 31 tonne after the engine afterburner 19,5 tons, which causes its thrust-to-weight ratio 0,65 and speed of 1700 km / h against 0,83 and 2410 km / h in fighter F-22. The engine of the new machine is made without a thrust vector control mechanism. Regarding the set of Stealth elements and the composition of the BREM, the F-35 does not differ from the F-22, except for the additional presence of the RL, intended for viewing the lower hemisphere and laser operation in the altimeter, rangefinder and target designation modes, including ground targets.
In conclusion of the description of the Stealth technology, it is necessary to dwell on its effectiveness in terms of reducing the visibility of aircraft in the radio range, as measured by the effective dispersion area. As a rule, in open descriptions of airplanes, minimum ESR values are given, achieved only in a static position when observed in the front sphere strictly in the frontal plane, therefore it is useful to remember that the ESR value differs by more than an order from other directions.
In flight, in general, due to the misalignment of the observed aircraft and the direction of its irradiation with radar, even in the front sphere, the EPR value increases severalfold. Similarly, the value of the EPR is influenced by aircraft armament, placed on the external sling. However, when placing weapons in conformal containers, ESR increases slightly.
If an external probing radio signal hits the surface of the aircraft’s radar antenna, its EPR value increases by an order of magnitude. Therefore, in the framework of the Stealth technology, a constant rotation of the antenna plane into the upper hemisphere is provided, thereby reducing the range and accuracy of target detection in the lower hemisphere.
EPR F-117 on the basis of combat use in Yugoslavia can be estimated at 0,025 sq.m. Promotional materials for F-22 and F-35 contain ESR values up to 0,0015 sq. M, which cannot correspond to the actual state of things, because the design of F-22 and F-35 does not have faceted airframe surfaces and thick cellular radio absorbing panels used. in the design of the F-117. Therefore, the most realistic value of the EPR F-22 and F-35 can be estimated in 0,1 square meters in a static position and 0,3 square meters in flight. For comparison, the EPR of airplanes that partially use the Stealth technology - Dassault Rafale and Eurofighter Typhoon in a static position without arms on the external sling is estimated at 1 sq. M, the EPR of new versions of the F-15E and Su-35C fighters - in 3 sq. M. The indicated EPR values are given for centimeter-range radar exposure conditions. In the decimeter range, the ESR increases by about 25 percent, in meter - by about 100 percent.
AWACS technology
In the area of radar detection of aircraft, radars of meter, decimeter, centimeter and millimeter ranges are currently used.
The meter range radars have antennas measuring several tens of meters, which limits their use to ground-based. In connection with this, the radar has a small radio horizon for detecting airborne targets, with an altitude of 100 meters, its magnitude is of the order of 40 km, which is less than the flying distance of anti-radar missiles such as AGM-88E and X-58E. At altitudes of more than 5 km, the meter radar, for example, the Russian radar "Nebo-ME" detects a target with an EPR 0,1 sq. M at a distance of 287 km.
UHF radars have a few meters in size, which allows them to be placed on air carriers, primarily on board AWACS aircraft supporting AWACS technology. At the altitude of the carrier 12 km, the radio horizon is on the order of 450 km, the instrumental range for detecting air targets over the radio horizon reaches 650 km. The AN / APY-2 Radar of the E-3 Sentry detects an air target with an 1 square meter EPR at the 425 km distance, and an 0,1 square meter EPR - at the 200 km distance.
Centimeter-range radars have an antenna with a diameter of 800-900 mm, which fits into the cross section of the fuselage of fighter aircraft and attack aircraft. The antenna is implemented in the form of a phased array of 1,8-2 thousands of transceiver modules. The radar beam is formed in a mixed electron-mechanical manner with a scan angle of + -150 degrees (AN / APG-77 F-22 fighter) and + -120 degrees (H035 Irbis of the Su-35C fighter). The detection range of air targets with an EPR 1 sq. M reaches 225 km, with an EPR 0,1 sq. M - 148 km. In LPI mode, the detection range is reduced approximately 2 times due to the lower signal power.
The millimeter-range radars have an antenna with a diameter of 150-300 mm, which is installed in the head part of air-to-air missiles with an active radar guidance system. The detection range of air targets ranges from 10 to 20 km, depending on the EPR. When performing a millimeter antenna in the form of an AFAR at a distance of one to two kilometers, resolution to the level of the silhouette of the aircraft can be provided.
DRLOU airplanes are equipped with RTR systems, communications and control of fighter and attack aircraft, which allows them to find radio sources, determine their coordinates and direct aircraft to air targets that fly without having to turn on-board radars. The latter, in turn, with the help of a radio command line induce a medium-to-long-range air-to-air missile at the target. When approaching the target, active RGSN missiles are included in the work.
Super maneuverability technology
Currently, the maximum range of launching air-to-air missiles on a non-maneuvering target at an altitude of 10 km is from 180 km (AIM-120D) to 300 km (RVV-BD). If the target performs an anti-missile maneuver, the launch range is reduced to 90-150 km due to the rocket’s fuel costs for counter-maneuvering.
After a missile targeting a medium / long range missile due to an antimissile maneuver of an aircraft or electronic countermeasures to capture a target, the struggle for air superiority is forced to enter the stage of close combat of enemy planes that use short range missiles with passive thermal seeker and gun armament. The close range air combat with the use of OLS begins with 40 / 20 km (the maximum range of the launch of short-range missiles RVV-MD / AIM-9X), without the use of OLS from the line of sight of the target.
The ability of an airplane to be the first to reach the target-engagement zone of a thermal seeker of a rocket (scan angle + -120 degrees) or the target-capture zone with a gun sight comes to the forefront in close combat. To this end, the aircraft carry out maneuvers in the air, seeking to enter the capture zone. The smaller the radius of the curves described by the aircraft in the air, and the smaller the loss of speed in the process of turns, the greater the chances of defeating melee air combat.
The maneuverability of the aircraft is ensured by its aerodynamics, strength due to withstand overload, thrust-to-weight ratio, the specific load on the wing, the degree of wing mechanization, and tail tail area. In the process of maneuvering, the angle of attack of the wings increases to supercritical with a drop in the carrying capacity of the wings and shading of the tail unit, up to the loss of aerodynamic controllability. After that, the aircraft can only be controlled by controlling the thrust vector of the engine.
The technology of super-maneuverability of aircraft is based on thrust-to-weight ratio exceeding 1 (after producing half the fuel reserve) and thrust vector control of engines, the number of which must be at least two to provide control in the roll channel. At the moment, only two cars meet these criteria: F-22 and Su-35С. All other types of aircraft after the transition into combat air combat inevitably lose to super-maneuverable machines, which was confirmed when modeling fights in computer simulators.
The super-maneuverable Su-35С aircraft has a thrust-to-weight ratio of 1,1 when producing half the fuel reserve, which exceeds the similar indicators of the F-22. The Su-35S engines contain deflectable nozzles, and their top-end modification (unlike the F-22 engines) has full-thrust thrust vector control, which allows the aircraft to rotate around the vertical axis 180 degrees, taking aim at the pursuing enemy without turning in the air. The design of the aircraft used elements of the Stealth technology in the form of a radio reflecting coating for the cockpit canopy and a radio absorbing airframe edge coating. Su-35С has the potential of modernization in terms of reducing the EPR to 1 sq. M due to the installation of radar-blockers, the collapse of the tail fin carcasses and the placement of outboard weapons in a conformal container between the air intakes.
EW technology
The airborne electronic equipment of the aircraft includes passive radar radiation warning systems and active systems to counteract this radiation. In accordance with the ideology of Stealth, only the first type of system is included in the F-22 and F-35 avionics. In contrast, the Su-35С avionics additionally contains active REB L-175В systems in the form of small-sized containers installed on the wingtips. The active system does not mask the aircraft in the radio band, but sends echo signals with a time delay to the side of the probing radar. Active systems are designed for individual protection of an aircraft by disrupting target acquisition by radar GOS of the millimeter-wave range of ground-to-air and air-to-air missiles.
In terms of confrontation with the AWACS technology, of interest are group active means of radioelectronic suppression of the operation of the DRLOU aircraft of the UHF type, the Russian “Tarantula” type, placed in a container on the external suspension of EW airplanes. In the direction of the probing radar, the transmitter emits a directional noise interference of high power, the magnitude of which obviously exceeds the power received by the probe radar, since the direct signal from the transmitter of interference is orders of magnitude more powerful than the signal reflected from the target.
Active means of electronic suppression work in conjunction with passive means of electronic reconnaissance, placed on the same EW carrier and determining the direction to the source of radio emission. When two or more EW carriers work together by triangulation, the distance to the radio source is also determined. Computing facilities, which are also included in the EW complex, make it possible to determine the ranges and coordinates of radio emission sources operating in continuous, pulsed or LPI modes.
In the development, there are interference transmitters with an AFAR antenna, which forms several beams of a radiation pattern in order to simultaneously suppress the corresponding number of radars (like the promising American NGJ complex). To supply equipment with electricity in containers are installed generators with turbines, driven in rotation by the oncoming air flow. As a rule, EW carrier planes are used in pairs, which allows more than doubled the area of electronic cover and at the same time "smears" in space the location of the carriers themselves (when synchronous operation of interference transmitters in the so-called blinking mode), thereby protecting them from rocket attacks.
Tactic of winning air superiority
You can evaluate the advantage of a technology to achieve superiority in the air by simulating an air battle in certain conditions:
- pre-suppressed air defense system from one side and the other;
- the numerical equality of fighter aircraft on both sides with a difference in the number of support aircraft (respectively, AWACS and EW) in proportion to the cost of the latter;
- conducting oncoming air combat in order to gain superiority in the air by destroying enemy aircraft (without attacking ground targets);
- the presence of adverse weather conditions, forcing to abandon the use of OLS up to the line of melee.
The number of aircraft involved in the oncoming airborne combat will be determined by its largest participant, the AWACS aircraft, whose radar has an instrumental range of about 500 km, while surveying the area sufficient for operational use of a maximum of an aviation fighter wing consisting of three squadrons with three links each the number of aircraft in 36 units. On the basis of the equality of the number of fighter aircraft, the opposite side can employ an aviation fighter regiment. To cover the actions of the air regiment, it is possible to attract 10 EW planes, based on the comparability of their total cost with the cost of one DRLOU aircraft.
The party using a bunch of Stealth + AWACS technologies can use the E-3 Sentry as an AWARD aircraft, and the F-22 (at best), which has six weapons with AIM-120D radar missiles ventral compartments, one rocket with a thermal seeker AIM-9X in the side compartments and a Vulcan 20-mm cannon.
The party using the Super-maneuverability + EW technology bundle can use the Su-34 with the Tarantula containers on an external hanger as an EW plane, and the Su-35С, which has six weapons with radar GOS RVV, as an aircraft to achieve air superiority -BD and six rockets with a thermal homing RVV-MD on an external sling, 30-mm gun GSH-30-1.
The E-3 Sentry barrage area is located at least 300 km away from the side separation line - the maximum range of the RVV-BD missiles when firing at a non-manoeuvrable target. The initial position of the F-22 before the battle was removed from the demarcation line by no less than 90 km - the effective range of the AIM-120D missiles when firing at a maneuverable target.
The tactical construction of the second-party aircraft grouping includes three 12 Su-35С and 2 Su-34 groups each and two distracting 2 groups Su-34 each. Distracting groups, using the fact of shielding their airspace by the probe beam of the AWAC radar, imitate aggressive actions towards the enemy. The initial position of the shock and distraction groups is not less than 250 km from the side separation line, based on the E-2 Sentry radar instrumental range.
The air combat initiative belongs to the second side, which is not tied to the area of the hawking of the AWACS plane. The flight of shock and distracting groups is carried out in the radar field E-2 Sentry. The convergence of the groups with the E-2 Sentry will be accompanied by maneuvering in altitude and azimuth in order to force the F-22 to launch AIM-120D using radio command guidance in the middle flight segment of the rocket and thereby reveal the number and location of the “invisible” aircraft. Naturally, F-22 in such a situation will refuse to attack the shock and distracting groups until they reach the start-up distance of the RVV-DB using the E-2 Sentry (300 km).
Under the shielding radar signal of the U-band E-3 Sentry radar, the F-22 fighters will be forced to use their centimeter-range radars when approaching the drums and distractions to the distance of effective use of AIM-120D in order to identify the aircraft composition of each of the shock and distraction groups and the corresponding distribution missiles out of stock. In case of approaching at a distance of 300 km, the AWACS plane will be forced to withdraw from the battlefield due to attacks using RVV-BD missiles, which will also force F-22 to switch on its radar.
However, using radar, F-22 will exit Stealth mode and will be detected by PTP Su-34 and Su-35С. Su-34, having completed their work, turned back, avoiding encounters with medium-range missiles, and F-22 and Su-35C will continue to come together, exchange missile salvoes, radio-command follower of medium-range missiles in flight until they receive radar GPS signals missiles on the capture of enemy targets.
Considering the opposition of onboard EW equipment of fighters, especially active EW Su-35С, some of the medium-range missiles will not reach their goals and the fight will inevitably enter the close combat airborne phase (the combat mission of both sides remains unchanged — air superiority). In this phase, the advantage of the Su-35C becomes undeniable: the best super-maneuverability speaks for itself, plus three times the number of missiles with thermal seeker on board.
As a result, it can be stated that the bundle of technologies Super-maneuverability + EW dominates over the bundle of AWACS + Stealth technologies.
Information sources:
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Information