In control of the sky: aerial dominance--the ability to employ assets with impunity in the airspace above enemy territory and forces--depends not only on achieving a high kill ratio in air combat (which increasingly relies on situational awareness provided by off-board sensors), but also on destroying the enemy's airfields, radars, Sam systems and control centres. (Fixed-wing).

Years ago this writer was involved in attempts to market British Aerospace's Stovl Harrier. These efforts were largely unsuccessful because the aircraft was subsonic, expensive and lacked credibility in the air-to-air role. In its favour, the Harrier had a unique ability to continue operations after its runways had been badly damaged, and to generate unprecedented sortie rates (delivering a massive amount of ordnance per hour) from sites close to the enemy. Less significantly, it could (thanks to a US Marine Corps initiative) also employ thrust-vectoring in air combat, though only as a last-ditch defensive manoeuvre.

Most air forces that we approached expressed curiosity about Harrier technology, but the US Air Force then had no interest whatever in acquiring Stovl capability. The argument put to us was that US Air Force runways could only be bombed if the service had lost control of the air, in which event the US would have lost the war. This scenario was simply unthinkable.

The Unthinkable!

In May 2002, reports began appearing that in US Air Force air combat simulations the thrust-vectoring Sukhoi Su-30MK was beating the Boeing F-15 not just occasionally, but every time. This was naturally a cause for serious concern, since the Lockheed Martin F/A-22 Raptor will not be available in significant numbers until 2007/2008, and since the US Air Force's F-15 will have to soldier on alongside it (perhaps indefinitely), in view of the limited number of F/A-22s that can be afforded. Furthermore, although the Su-30MK series has so far been purchased only by China and India, there are worrying indications (e.g., from Brazil and Malaysia) that other nations will follow suit.

The starting-point for these simulations is presumably a head-on encounter at medium altitude, with the Su-30MK firing a BVR (beyond visual range) air-to-air missile before the F-15 can launch. Both aircraft have massive radar signatures, and are thus aware of the opponent's position, but the Su-30MK armament evidently out-ranges that of the F-15.

The extended-range 350 kg Vympel R-27RE has a nominal maximum range of 130 km, and the same company's new-generation 175 kg RVV-AE (often referred to in the Western press as the R-77) has a corresponding figure of 75 km. The range of the somewhat lighter 157 kg Raytheon AIM-120 has not been published, but it is believed to be somewhat in excess of 50 km. Its range may not be vastly inferior to that of the RVV-AE, but it certainly cannot compete with the extended-range R-27, which is in service in two forms: the R-27RE with semi-active radar guidance, and the infrared homing R-27TE (a marginally lighter missile at 343 kg, with a range of 120 km). Standard Russian firing procedure is reportedly to follow the R-27RE with an R-27TE. The R-27AE with active radar guidance is thought to be not yet in service.

It is because of this East-West imbalance in BVR missile ranges that a six-nation European team is working on the ramjet-powered MBDA Meteor, the development contract for which was signed in December 2002. Vympel has meanwhile proposed the ramjet-powered 225 kg RVV-AE-PD, which is expected to give at least as much range as the R-27RE/TE. Although Russia may not at present have the funds to develop the ramjet, Vympel is working on what has been referred to as a K-77M, using a lofted flight profile to extend range. A derivative of the RVV-AE is being developed in China for the Su-30MKK. This Project 129 uses a dual-burn rocket motor to increase range and enhance terminal manoeuvrability.

Reverting to the US Air Force simulation, immediately after speeding out the first shot(s), and before the F-15 is close enough to respond with an AIM-120, the Su-30MK uses thrust-vectoring to make a square-turn, disappearing from the F-15's pulse-Doppler radar display and descending into ground clutter. In a two vs. two encounter, the Su-30MKs would split on either side of the incoming F-15s.

Using its Ural Optical & Mechanical Plant (UOMZ) OLS-30 Irst (infrared search and track) device to follow the F-15, the Su-30MK can turn gently to keep it (assuming it has survived the BVR shots) at 90-deg off-axis, thus remaining invisible to the latter's radar. The former pilot can then make another thrust-vectoring turn and employ his NSTs-27 helmet-mounted sight to fire a Vympel R-73 short-range air-to-air missile from below the F-15, presenting a sore-thumb infrared target against the cold background of the sky. Although the Su-30MK loses speed in each of these violent manoeuvres, its high thrust/weight ratio gives it excellent acceleration and (if desired) allows it to escape from the area.

What Went Wrong?

If the US Air Force now acknowledges doubts regarding its ability to ensure air superiority anywhere in the world, this situation has arisen primarily because the service planned to replace all F-15Cs with what were then designated F-22s, a plan that no longer appears economically feasible. The Air Force built a system-of-systems around the F-22, which was to enter service at the end of 2005, before any serious foreign threat could possibly materialise. With hindsight, this was a gamble, because the weapon system developed does not work as well as that for the F-15.

In essence, the US Air Force decided to exploit the quantum leap in stealth and supercruise capability provided by the F-22 by developing an air combat system that would generate a long-lasting, order-of-magnitude advance in effectiveness, not only relative to anything the Russians might produce, but also over anything that its European allies might develop. However, rather than pushing the limits with every element of the system, the Pentagon used the F-22's unique combination of performance and low observability to minimise the development cost of its air-to-air missiles.

This is especially true in the case of the AIM-120, which was not required to break any records in terms of effective range, since it was intended to be fired from an aircraft that an enemy could not detect until it is too late. Launched from an F/A-22 supercruising at Mach 1.5, the AIM-120 can achieve a 50 per cent greater range than from a high-subsonic launch. Its limited range-demand fits in with the need for internal carriage, since this restricts its dimensions (and thus launch weight).

Cost saving has also played a role in the selection of the Raytheon AIM-9X Evolved Sidewinder, which is intended for use in both WVR (within visual range) and near-BVR engagements. Following a statement to Congress by the US Air Force Chief of Staff in April 1996, that the service's existing AIM-9M was only the fourth-best short-range air-to-air missile in the world (presumably after the Vympel R-73, Rafael Python 4 and MBDA Mica), the AIM-9X development contract was awarded (to what was then Hughes) at the end of that year. It was won with a proposal that retained the warhead, fuze and rocket motor of the AIM-9M, but introduced a new control system and aerofoil surfaces, thrust-vectoring, and the imaging infrared focal plane array that Hughes was developing for the Asraam, now in the hands of MBDA.

The 85 kg AIM-9X was to be used in combination with the Vision Systems International (Kaiser Electronics/Elbit Systems) JHMCS (Joint Helmet-Mounted Cueing System), although this was contracted separately. To exploit the full potential of the AIM-9X, the launch aircraft required a new Modular Mission Computer with Suite 4-series Operational Flight Program software (the 4M for the F-15A/B/C/D, and the 4E for the F-15E). While still in the development phase, low-rate initial production of the AIM-9X was launched in November 2000. It is believed that the first change in the P3I (pre-planned product improvement) programme is likely to be a switch to a more powerful rocket motor.

The Pentagon's plan called for the AIM-9X to enter service with the two threshold aircraft, the F-15C/D and the US Navy's Boeing F/A-18C/D in 2003 and 2004 respectively. Clearance on the F-16C/D is currently expected in 2006/2007, delayed by the need to replace its new Suite M2.3+ software with Suite 4. There have been proposals to put the AIM-9X on some F-16C/Ds ahead of the software upgrade, to benefit from its longer range, improved counter-countermeasures, and increased look-angle (once locked-on). The AIM-9X will later go on the F-15E, F-22 and F/A-18E/F.

What To Do?

Fortunately, in rising to the new challenge of its air supremacy, the US Air Force does not necessarily have to buy the Su-30MK, R-27RE/TE, RVV-AE, OLS-30 and NSTs-27, or even restore the original buy of F/A-22s.

The service will doubtless respond to the problems arising from the cutbacks in F/A-22 production by retaining and upgrading more F-15s and F-16s, pending availability of the stealthy Lockheed Martin F-35. The US Air Force will now keep around 210 (rather than 179) F-15C/Ds until at least 2020. In the short-term, the survivability of the F-15 in the scenario discussed above is being enhanced by the introduction of Link 16, providing a jam-proof datalink with Awacs and keeping the F-15 aware of what the Su-30MK is doing, whether his radar can see it or not. The F-15 is also receiving an upgraded Raytheon APG-63 radar and F100-PW-220E engines. It will have the Raytheon AIM-9X and JHMCS, and is due to be fitted with the BAE Systems ALQ-214 IDECM (Integrated Defensive Electronic Counter-Measures) suite, which includes the company's ALE-55 fibre-optic towed decoy.

The US Air Force is also trying to arrange air combat exercises with Indian Air Force Su-30MKIs, the world's first in-service fighters with thrust-vectoring. Ideally, these should take place over an instrumented range in the US and will hopefully allow tactics to be developed that reduce the expected loss-rate of the F-15.

Although low in the pecking order for the AIM-9X, the F-16C/D is already cleared to use the AIM-120. In the specific air combat scenario described earlier, the relatively lightweight F-16C/D is reported to out-perform the F-15 by virtue of its smaller radar signature. This allows it to approach closer to the Su-30MK before being detected, and thus provides an opportunity to fire a preemptive AIM-120.

By the same token, the diminutive AIM-120-armed Saab/BAE Systems Gripen could well out-perform the larger Eurofighter Typhoon and Dassault Rafale in this particular situation. A Gripen armed with the Meteor and the short-range BGT Iris-T will be a very serious proposition indeed. On the other hand, larger fighters such as the F-15, Typhoon and Rafale will always provide better warload radius performance than a lightweight.

Thrust-Vectoring

Aside from putting all its eggs in the F/A-22 basket, the US Air Force may also have been at fault in its assessment of thrust-vectoring. The Pentagon has funded extensive thrust-vectoring trials with the Boeing NF-15B Agile Eagle, the Lockheed Martin F-16 MATV (multi-axis thrust-vectoring), the F/A-18 Harv (High Alpha Research Vehicle) and the Rockwell (now Boeing) X-31. However, it decided to delay the introduction of thrust-vectoring on a production fighter until the F/A-22 is delivered.

It may be conjectured that those responsible took the view that thrust-vectoring involved not only additional expenditure, but also a significant weight penalty (especially in the case of a retrofit, requiring forward ballast), and that its principal attraction related to a last-ditch defensive manoeuvre at low airspeeds. Whereas extended dogfights have traditionally led to fighters losing energy (airspeed and altitude), this is less likely to occur with modern thrust/weight ratios. It may have been further argued that a fighter designed from the outset for stealth will have two-dimensional exhausts to reduce its infrared signature, in which case pitch-vectoring will involve less change and a smaller weight penalty. It may have been contended that the potential STOL benefit of thrust-vectoring can be exploited fully only if the aircraft is designed from the outset to rotate to extreme nose-high attitude while still on the runway.

Thrust-vectoring was introduced on the NF-15B as the second phase of the US Air Force Flight Dynamics Laboratory's STOL Manoeuvring Technology Demonstration (SMTD) programme, following tests with moveable canards and a stronger undercarriage. Two-dimensional (rectangular-section) nozzles developed by Pratt & Whitney were added to provide thrust-vectoring in pitch (20-deg up/down) and thrust-reversing. Following trials between 1989 and 1991, the NF-15B was fitted with P&W pitch/yaw balanced-beam nozzles that could turn the thrust through 20 deg in any direction. The Active (Advanced Control Technology for Integrated Vehicles) programme was to explore thrust-vectoring in supersonic flight, Mach 1.95 being reached in 1996 tests.

The F-16 MATV began as a private venture by the airframe manufacturer and General Electric. Since the US Air Force initially declined to support the programme, Israel offered to loan an F-16D for the tests, but in 1991 the US Air Force's Wright Laboratory became interested, and Israel withdrew. General Electric's Aven (Axisymmetric Vectoring Exhaust Nozzle) was attached to the jet-pipe of the F110-GE-100 of the NF-16D Vista (Variable-stability In-flight Simulator Test Aircraft). The Aven could deflect the jet through 17 deg in any direction, and passed the resulting loads through the jetpipe to the engine, thus facilitating retrofit. Some 320 kg of ballast was added on the inlet hardpoints. Over 130 flight hours were accumulated in the 1993-'94 timeframe, exploiting controlled flight above the normal 25-deg angle of attack limit and thus achieving higher instantaneous turn rates. It also demonstrated a sustained angle of attack of 86 deg, and 180 deg transiently (i.e., flying back wards). The NF-16D was later equipped with a Pratt & Whitney vectoring nozzle that would fit any F100 engine and provided 20-deg of vectoring, but the planned flight test programme was cancelled in 1997.

The US Navy/Nasa F/A-18 Harv is a relatively crude test vehicle, using externally-mounted vanes to deflect the F404-GE-400 jets for pitch and yaw control, allowing the aircraft to manoeuvre at up to a 65-deg angle of attack. The vane system alone adds 1000 kg, but it is not clear how much ballast is necessitated by this installation (some being associated with the spin chute).

The X-31A is a US/German programme that was originally intended to explore the air combat potential of the Herbst post-stall manoeuvre, named after MBB's Dr Wolfgang Herbst, who proposed it in the mid-1970s. In 1985, the Darpa funded Rockwell studies, which led to two-nation funding for the construction and testing of two X-31A air vehicles, the first of which flew in late 1990. The trials, which demonstrated manoeuvring at a 70-deg angle of attack and gave a 10:1 exchange-ratio in simulated combat with an F/A-18, were completed in January 1995. Testing of the X-31A was resumed in February 2001 under the Vector (Vectoring Estol Control Tailless Operation Research) programme, to evaluate the potential for Extreme STOL and for eliminating the vertical tail. Vector will eventually lead to a landing approach flown at a 40-deg angle of attack and de-rotation to 12 deg immediately before touchdown. Boeing is the prime contractor, partnered with Eads. The customer is the US Navy, teamed with Germany's BWB procurement agency.

Possibly inspired by America's NF-15B Agile Eagle programme, in March 1989 Soviet vectored-thrust trials began with a modified Su-27 prototype (T10-24). In April 1996 a further prototype (T10M-11) with canard surfaces and thrust-vectoring, temporarily designated Su-37, made its first flight. It was demonstrated impressively at the Farnborough air show five months later.

At that stage the Su-37 nozzles, developed by Lyulka, were operated with standard hydraulic fluid and could only move in pitch, 15 deg up/down. For the production Su-30MKI the Al-31FP engine is equipped with a new AL-100 nozzle, jointly developed by Lyulka and the Ufa Engineering Industrial Association, and capable of turning through 32 deg off-axis in any direction. The nozzle weighs 100 kg, adding 7 per cent to the dry weight of the engine. Thrust-vectoring is selected by a super-manoeuvrability switch, but the pilot continues to use the normal flight controls. For the AL-100, fuel is used as the hydraulic fluid, and there is a pneumatic system to centralise the nozzles in the event of system failure.

Lyulka has also exhibited a thrust-vectoring nozzle for the AL-55 engine, intended for lightweight fighters and training aircraft. One MiG-29OVT with thrust-vectoring Klimov RD-133 engines has been built, and was first exhibited at Moscow in late 1991.

Supporting Cast

This discussion has concentrated on developments in air combat, but there are (as indicated earlier) many other aspects to the struggle for air dominance. For example, the fighter is increasingly dependent on target information from external sources, such as AEW&C aircraft. In this field the Boeing 707-based Awacs is being replaced by the same company's 767 series.

Lower down the scale, the B737 AEW&C aircraft currently appears to be beating off competition from the Airbus A320. Other platforms include the Embraer EMB-145SA, carrying the Ericsson Erieye radar, and the Ilyushin Il-76 with the IAI/Elta Phalcon. The Northrop Grumman E-2 series is meanwhile being upgraded (as evidenced by deliveries of new-build Hawkeye 2000s) to further prolong its life.

The fighter is equally dependent on support from tankers such as the Boeing KC-767 and Ilyushin Il-78, and proposed variants of the Airbus A330. The use of buddy-buddy systems' is illustrated by India's plan for all its licence-built Su-30MKIs to have provisions for Flight Refuelling Mk 32-75 pods on their centre lines, presumably extending the radius of similar strike aircraft by one-third.

Air opposition can also be minimised by attacks on airfields, which is the primary mission of the MBDA Apache air-to-surface missile, dispensing runway-piercing submunitions. During Operation Desert Storm, aircraft shelters were destroyed very effectively by 900 kg Raytheon Paveway laser-guided bombs, and it may be that by 2006 the much lighter (115 kg), GPS/INS-guided SDB (Small Diameter Bomb) will be able to perform the same function. The SDB is being competed by Boeing and Lockheed Martin. Command and control centres can be attacked by penetration weapons such as the MBDA Storm Shadow and the Eads/Saab Bofors Dynamics KEPD350.

Enemy fighters represent only one threat to combat air operations. Ground-based air defence systems (Sams and AAA) are steadily improving in effectiveness against tactical aircraft, and a long-range Sam threat has been developing against stand-off assets such as AEW&C aircraft, tankers and jammers. Existing US Air Force Sead (suppression of enemy air &fences) assets such as the F-16CJ and Northrop Grumman's EA-6B may well be replaced by the EA-18 derivative of the F/A-18E/F.

Anti-emitter missiles have a vitally important role to play. Current leaders are the Raytheon AGM-88B Harm (High-speed Anti-Radiation Missile) and the ramjet-powered Zvezda-Strela Kh-31P. The Pentagon is funding a series of developments for the Harm, leading to the Hsarm (High-Speed Anti-Radiation Missile), which could enter the SDD (system development and demonstration) phase in FY2006.