Cannons once again found their way into the design of fighter planes. The problem with cannons is that they had to be fired at aerial targets from the astern quarters and any manoeuvring by the target aircraft increases the difficulty for the attacker dramatically reducing its effectiveness. The answer lay in a weapon such as a missile that can be fired immediately on detection of the target visually or by onboard sensors, irrespective of the position of the enemy aircraft relative to the attacker. Design of air-to-air combat missiles is slowly but surely evolving towards ‘fire-and-forget’ capability.
Missiles for Aerial Combat
The Korean War was the testing ground for an all-jet combat environment with the American F-86 Sabre and the Chinese MiG-15 fighter aircraft battling for control of the Korean skies. Aerial combat tactics were similar to that of World War II even though the flight envelope of these jets significantly exceeded those of the famed Spitfire, Hurricane and the Me-109. Air-to-air guided missiles were propounded in the 1950s as the panacea to overcome the challenges of air combat by these faster jets.
The early versions of the Soviet MiG-21 aircraft were designed to carry only guided missiles and had no cannons for air combat. Similarly, in the United States (US) the first models of the F-4 Phantom were armed only with AIM-4 Falcon and the AIM-9 Sidewinder missiles. Fighter tactics were driven by the tactical concepts of directing interceptor aircraft by ground-based radars towards intruding enemy aircraft and engaging them with missiles at beyond visual range. The classical dogfight or close combat of the World War II era then appeared consigned to history. However, the Vietnam and the Yom Kippur Wars re-established the relevance of close combat and the need to have weapons for high altitude interception as well as for dogfight at low and medium altitude.
Air-to-air guided missiles were propounded in the 1950s as the panacea to overcome the challenges of air combat…
Cannons once again found their way into the design of fighter planes. The problem with cannons is that they had to be fired at aerial targets from the astern quarters and any manoeuvring by the target aircraft increases the difficulty for the attacker dramatically reducing its effectiveness. The answer lay in a weapon such as a missile that can be fired immediately on detection of the target visually or by onboard sensors, irrespective of the position of the enemy aircraft relative to the attacker. Design of air-to-air combat missiles is slowly but surely evolving towards ‘fire-and-forget’ capability.
The first time that the Indian Air Force (IAF) fired air-to-air missiles in anger was on the morning of December 04, 1971, by a pair of MiG-21 on Combat Air Patrol (CAP) over Dhaka for the protection of a Hunter aircraft running in at low level to strike Tezgaon airfield in the then East Pakistan. Two F-86 Sabres were scrambled to intercept the approaching strike force. As the Sabres got airborne, they were spotted by the CAP leader who positioned himself behind the Sabres and launched the K-13 missiles. Unfortunately, both the missiles missed the Sabres and the Hunters were left to fend for themselves when they were intercepted. The IAF has come a long way since then.
Generational Change
Air-to-air missiles are categorised by the improvements in each generation of weapon systems. The MiG-21 aircraft of the IAF were armed with the first generation K-13 missiles which had an infra-red seeker with a narrow field of vision optimised for interception at high altitude. However, even a gentle manoeuvre by the target broke the missile lock. The second generation missile had more sensitive seekers and a wider field of vision but the attacking aircraft had still to position itself behind the target. The third generation brought about a significant change and the “all aspect” missiles appeared on the scene. These missiles had better sensors and allowed the attacker greater freedom to fire with the target “side on” but the field of vision was still very narrow. The biggest advantage was that the attacking aircraft did not have to be behind the target when launching the missile. While missiles such as the French Matra Magic-2 and the Russian R-60 claimed “all aspect” capability, they fell short of the fighter pilot’s expectations.
The Russian Vympel R-73 was the first of the fourth generation air-to-air missile and provided a quantum jump in capability. It used an advanced cryogenic seeker to improve the “capture” of the target, was resistant to infrared countermeasures by the target aircraft and the agility of the missile was increased by thrust vectoring. The missile’s field of vision was wider than that of the fighter aircraft’s radar but this dichotomy was corrected by helmet-mounted sights. With these improvements the fourth generation missiles could be used against low flying targets as they had a “look down, shoot down” capability which cut through the ground clutter. The R-73 was later upgraded to an improved version, the R-74M which features fully digital and re-programmable systems for greater versatility.
In 1990, after the unification of East and West Germany, the German Air Force found itself with a large stockpile of R-73 missiles. Performance evaluation in mock combat via-a-vis the Sidewinder AIM-9L showed that the R-73 had been grossly underestimated by the West. The Russian R-73 was a wake-up call for countries that had no access to Russian technology triggering the development of the Sidewinder AIM-9X, the IRIS-T, MICA-IR and the Python IV missiles.
The Russian Vympel R-73 was the first of the fourth generation air-to-air missile…
The fifth generation air-to-air missiles have far better seekers that allow the missile to “see” images rather than detect points of infra-red radiation. The new sensors, coupled with digital signal processing, have improved weapons capability and provide the following benefits:
- Sensors can detect aircraft despite infrared counter-measures
- Provides enhanced firing range and the ability to track small low flying aircraft and UAVs.
- Capability to target vulnerable parts of the aircraft instead of merely homing on to the infrared radiation from the engine exhaust.
The IRIS-T made by the German-led consortium, the Russian R-73M2, the Sidewinder AIM-9X, and the Israeli Python 5 missiles fall into this category.
The technological advances of air-to-air missiles in the last 20 years have made them the primary weapons of modern fighter aircraft. Missiles have been designed for specified ranges, for specific guidance systems and even for specific targets such as the AWACS.
Air-to-air missiles can be clubbed into three distinct categories, highly agile short-range Within Visual Range (WVR), less agile but long range Beyond Visual Range (BVR) and very long BVR missiles. The transition from the third generation to fifth generation missiles has been the result of technological developments which contributed to incremental improvements in capability as under:
- Analogue electronics have been replaced by digital software designs giving the missile a “smart’ capability for guidance algorithms, flight path energy management and better techniques for overcoming counter-measures by the target.
- Replacement of semi-active guidance systems by autonomous active homing systems allowing fighters to break away earlier but more importantly, permitting engagement of multiple targets.
- Seeker technologies have dramatically increased the sensitivity of the missile. The shift from mechanically oscillating seekers to focal plane arrays and the use of CCD TV imaging devices give missiles the ability to neutralise counter-measures and discern targets amidst the clutter.
- Increase in the flight time of medium range missiles with the introduction of solid propellant ramjets.
The international arms bazaar offers fifth generation air-to-air missiles for every mission and the salient features of some of the latest missiles are elaborated on in the succeeding paragraphs.
MICA
Missile d’Interception, de Combat et d’Autodefense or MICA made by MBDA, is in operational service with the French Air Force and Navy on the Mirage 2000 and Rafale and is a dual purpose Within Visual Range (WVR) and also a BVR missile. The BVR version MICA (EM) RF has an Active Radio Frequency seeker and the WVR close combat missile has a dual waveband Passive Imaging Infra Red seeker.
MBDA claims that both types of missiles are fully BVR capable and can track multiple targets at extended ranges with the two inter-operable guidance systems that are optimised to hamper enemy counter-measures. The missile was designed as a multi-aircraft system that could be integrated with any modern fighter and has Lock On Before Launch (LOBL) and Lock On After Launch (LOAL) capability thus giving it a 360-degree envelope. French pilots who fired the MICA-IR over Libya report that its sensor alone is a useful input to their systems, and its passive seeker with LOAL capability means that it can be fired from Beyond Visual Range at enemy aircraft, without generating any warning to the target from its radar warning receivers. India has already ordered 490 missiles as a part of the Mirage 2000 upgrade and this gives MBDA an advantage of having a foot-in-the-door and exploring the possibility of covering India’s market for air-to-air missiles in the coming years.Rafael Python 5
The Python 4 made by Rafael Advanced Defense Systems, Israel was the first fourth generation missile in production by the West. It was designed to combine the capability of very high sustained G forces during launch and flight with a long duration burn motor to be used in conjunction with a helmet-mounted sight. The Python 5 uses the same aerodynamic airframe inertial navigation system and rocket motor as the Python 4. It has BVR and LOAL capability as also all aspect, all direction including “over the shoulder” attack capability. The missile features an advanced electro-optical imaging infra-red seeker which scans the target area for hostile aircraft and then locks on for the terminal phase. The dual waveband seeker will enables the Python 5 to engage small, low-signature, low-flying targets in adverse weather and cloudy conditions. It has been employed successfully by the Israeli Air Force against UAVs.