The Eagle Still Flies High

Boeing's F15

1st Jul 2010


First extending its wings way back in July 1972 as the McDonnell Douglas F-15, the Eagle has played a major operational role with the US Air Force for 35 years yet in the second decade of the 21st Century export customers are still taking delivery of upgraded versions - after a production run of nearly 40 years. For an air superiority fighter it is an impressive legacy – equivalent to a Sopwith Camel of the First World War remaining in production into the late 1950s! Today’s Boeing F-15 Eagle is a radically more capable multi-role fighting machine than the original Mach 2 aircraft that was designed to replace the F-4 Phantom II, and its distinctive twin-tailed outline is likely to remain a familiar sight in Asian skies for decades to come, such is its operational effectiveness and “Top Gun” pilot appeal.

The F-15 Eagle, together with the US Navy’s Grumman F-14 Tomcat which was introduced within a similar timeframe, ushered in the era of big, powerful supersonic weapons systems that could take air superiority into the realms of air dominance. In retrospect it can be seen that the clear advantage of the F-15’s high thrust-to-weight ratio, and resulting combat agility compared to its potential 70s era Soviet adversaries, helped bring about an end to the Cold War. It forced the Russians to develop a new generation of combat aircraft, including the Mig-29, and later the Sukhoi Su27 family, at a time when the USSR was struggling with a failing economy, and couldn’t keep up the pace.

In due course, over three decades, the Su-27/30 series became outstanding combat aircraft, but meanwhile Western designs had moved on as stealth became more important to strategists in the USAF than dash speed. Direct East/West confrontation may have become history in Europe, but the adoption of highly capable Mig and Sukhoi fighters by many Asian air forces, including in India, Myanmar, China, Indonesia, Bangladesh, North Korea and Malaysia, acted as an incentive for other air forces in the region, including the USAF Pacific Command, to continue to develop and operate upgraded F-15 Eagles, which can still offer a significant performance edge over rivals, including the more widely procured F-16 family. The Chengdu FC-1, which is known as the JF-17 in its export version, and which has been developed with Pakistan, is the Chinese equivalent to the F-16, and this is expected to make its way to several Asian customers, further boosting the justification for retaining the F-15 as an air superiority asset.

The original role of the USAF F-15A, B and C models was air defence with the fully operational D model used for conversion and advanced operational training. From 1979 the C model became the standard production aircraft in US service, and this served worldwide, from regular and Air National Guard defence squadrons in the US homeland to air defence air wings in the Pacific, Europe and later, the Middle East. The F-15 Eagle features a large, strong, wing, and a fuselage that is well placed to carry additional pylons for fuel tanks, electronic warfare and reconnaissance pods, air-to-air missiles, bombs and air-to-surface missiles. While such stores could be carried from the earliest days, the tactical strike/attack potential of the machine came into its own with the more developed E model, which introduced not only uprated engines and radar, but a huge number of improvements to the avionics and weapons systems, as well as a beefed-up structure. Although outwardly almost identical to the F-15D, in many ways the F-15E, which first flew in 1986, was a new multi-role fighter. It carried a crew of two, sitting in tandem as in the D model, but this comprised a pilot and weapons systems operator, who was now required to monitor the advanced displays and operate the weapons and reconnaissance equipment controls in the rear cockpit.

Even with the latest operational computers and software in place, the mission tasking burden had now outpaced what could be expected from a single pilot. With the coming of smart precision attack weapons and digital data distribution, the F-15E became a modern airborne battleship, quite able to look after itself in the combat zone, armed with a mix of short and medium/long range air-to-air missiles and a 20mmVulcan cannon, plus a phenomenal load of attack weapons, including Maverick and Harm, AGM-154 JSOW and Paveway laser-guided bombs. A total of 24,500lbs of weapons could be carried on 18 different pylons, and this was further enhanced when fuselage-mounted conformal tanks, carrying even more fuel and extra pylons, were added. In reality, the maximum upload was rarely, if ever, carried in action, preference being given to a mix of self-defence and attack weapons, defensive aids or reconnaissance pods and long-range drop-tanks. Data link pods could be fitted under the fuselage and the multi-mode AN/APG-70 radar brought high-resolution ground-mapping as well as air-to-air and air-to-ground modes.

Export customers were soon drawn to the Eagle. In the case of the Japanese Air Self Defence Force, the initial batch of 14 F-15C based F-15Js and F-15DJs were delivered from St Louis before being put into licensed production in Japan by Mitsubishi. These have provided the country with its primary air defence capability since the 1980s and are proving hard to replace, as Japan was refused US permission to order F-22 Raptors and is now considering all remaining options including an indigenous Mitsubishi ATD-X design, but which is unlikely to be given the go-ahead on cost grounds. Israel developed its new and ex-USAF F-15s into very capable new versions, fitted with Elbit displays, helmet sights and new weapons and a sophisticated defensive aids suite. The F-15E-based two-seat F-15I Thunder variant is the most potent. A rolling programme of Israeli-developed digital onboard systems and weapons upgrades is keeping its F-15I fleet up-to-date as air dominance platforms, and likely to remain in service until replaced, as seems most likely, by the F-35 JSF in the coming decade.

The Republic of South Korea faces perhaps the most imminent threat of conflict, if not physical invasion, in the whole Asia Pacific region from an aggressive neighbour, and so the selection of a new air superiority fighter was a key concern until the F-15K won a bitter battle (against the European Typhoon and Rafale) with Boeing emerging the winner. At one time this was seen by both Eurofighter and Dassault as a “must win” breakthrough contract to break the US monopoly on new fighters for the Asia Pacific market, and a great deal of effort went into trying to do a deal. In the end, as was perhaps inevitable in such a US dominated political and defence environment, the US offering, this time from Boeing, emerged victorious. This important win, against later-generation hi-tech competitors, underlined the persistent appeal of the Eagle, even into a new century, and established the type in modernised format as a more than worthy platform. The F-15K brought further radar and weapons improvements, and the latest “glass” cockpit displays, to an already impressive F-15E baseline product, with the potential for even more advanced radar and weapons upgrades yet to come. With the highly unpredictable North Korean forces on its doorstep, and only a few minutes flying time from its major cities and air bases, the ROK Air Force now has what is probably, with the exception of the USAF F-22s, the region’s most capable air superiority fighter strengthening its front line. This is one theatre of operations where a genuine Mach 2.5 supersonic dash capability might just be needed.

For many years the Republic of Singapore Air Force has been one of the region’s best-equipped air powers, despite the small size of this city-state. It has a large number of advanced F-16 fighters in service, but decided that to safeguard a vital air superiority margin over powerful Su-30 aircraft operating in neighbouring countries, it needed a heavyweight combat aircraft with greater range and payload. The “keep off” factor was a key regional security requirement, so once again a tough competition was fought out amongst all the major Western rivals, which included Typhoon, Rafale, the F/A-18 E/F Super Hornet and an upgraded F-15E variant, similar to the K version for South Korea.
In service, the new F-15S will represent a considerable leap in capability over the ageing McDonnell Douglas A-4 Skyhawks they will replace.

The F-15S has two General Electric F110-GE-129 engines each offering 29,000lbs of thrust and it is believed that Raytheon’s advanced AN/APG-63(V)3 actively scanned array radar will be fitted. This is now being offered as a huge advance in multi-target identification and tracking performance with far fewer components and moving parts and extremely high capability and reliability. It is also lighter and easier to maintain than previous radars fitted to the F-15 family of jet fighters. The S model will have the latest Link 16 data distribution system to maximise its ability to exploit networked secure communications between other fighters, airborne command and control (AEW&C) air platforms and ground stations. By being able to share situational awareness between these operating nodes, the new F-15S will itself become a vital airborne C4I platform as well as multi-role combat aircraft. Its crews will have the advantage of fully integrated onboard systems and glass screen displays which are compatible with the wearing of night vision goggles. Helmet sights and an integrated defensive aids system are also likely features, though full details of the RSAF’s F-15S specification have not been announced to date.

As if to underline the F-15’s re-birth as a 21st Century multi-role fighter that can still hold its own against the best competitive products from Europe, early last year Boeing unveiled its most sophisticated F-15 variant yet, dubbed the Silent Eagle. This is a private company-funded proposal and aims to offer a much stealthier airframe, claiming to be far more affordable compared to the F-22 and F-35, while seriously reducing the radar cross-section. The most obvious visual difference compared to earlier Eagles, when this was announced, was the adoption of new twin tails, canted outwards in a gentle “V” shape. This has subsequently been dropped. The extra stealth comes from new radar-absorbant coatings and a clean weapons carriage configuration, using internal missile bays created from within the conformal side additions to the fuselage. Seen by some observers as an attempt by Boeing to offer a follow-on option for the USAF after F-22 production ceases, and if JSF/F-35 costs continue to rise, the Silent Eagle has not yet attracted official USAF support. This is perhaps not so surprising in view of the ballooning US defence budget, but the work that has gone into developing the Silent Eagle could yet have export applications, and help to keep the type in production for a little longer.

Boeing has already released computer images of a radical tail-less future combat aircraft, aimed at the US Navy initially, known as Next Generation Air Dominance (NGAD) that could be manufactured in either manned or unmanned versions. Although everyone thought that the F-16 and F-18 were supposed to be replaced by the JSF/F-35, and the F-15 by the F-22, now along comes something completely different! In the meantime, the F-15 Silent Eagle initiative shows that clearly there is plenty of life yet in this old bird.
 

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