The Eagle

Part 4 - Mud Hens

Æthelberht, Going Postal
A USAF F-15E Strike Eagle

So far we’ve covered the Eagle’s inception, its design and features and its combat record as an air superiority fighter. There’s one more part to the Eagle’s tale, and that one involves dropping bombs on peoples’ heads.

When talking about the F-15 you’ll often hear the mantra of the designers was “not a pound for air to ground”. This line actually came out of the USAF’s F-15 project office and is mistakenly taken as meaning the F-15 was designed without any air to ground capability. In fact the F-15 was designed with the carriage of air to ground ordnance in mind as a secondary role.

As I explained in an earlier article, the F-15 was around three times more expensive than the F-4 Phantom II it replaced. The F-15 was at the time the most expensive fighter ever produced and as such required careful image management. Nothing was to be allowed to undermine the F-15’s public image of being a no compromise, world beating fighter. Certainly nothing as vulgar as dropping bombs on things, such a mundane task was the purview of lesser aircraft. No, the F-15 was to be seen by the public and the politicians as a thorougbred fighter without peer in order to justify its extraordinary cost. This same approach of “reassuringly expensive” was later applied to the F-15’s replacement, the F-22 (remember that adjusted for inflation, an F-22A Raptor is four times the cost of an F-15C).

In fact, when General Dynamics were developing the F-16 for the USAF they intended for it to be able to carry the AIM-7 Sparrow beyond visual range missile but the USAF directed GD to remove the capability from the F-16 as they didn’t want the cheaper fighter stepping on the F-15’s toes.

Thus, in its early years of service at least, the USAF viewed the F-15 as a pure air to air platform. The Israelis were a bit more forward thinking. It appears the Israelis recognised very early on the air to ground potential of the F-15 and had been very quietly modifying at least some of their F-15 Baz aircraft to turn them into long range strike and interdiction platforms. On 1st October 1985 a force of 8 F-15 Baz supported by a Boeing 707 tanker of the Israeli Air Force made the almost 3,000 mile round trip to bomb the PLO headquarters in Tunis. They remained undetected by Egyptian and Tunisian air defences, and even US Navy vessels in the Mediterranean. They achieved complete surprise and destroyed the PLO headquarters with GBU-15 electro-optical guided glide bombs.

Many of the details surrounding Operation Wooden Leg are sketchy and still classified, but what we do know is the F-15s were modified earlier that year with Conformal Fuel Tanks (CFT) to extend their range, had the necessary modifications to allow them to employ the GBU-15 and possibly had modifications made to their radars and electronic warfare systems.

The Israelis had made a very effective demonstration of the F-15’s potential utility as an air to ground platform.

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A USAF F-15E dropping an EGBU-15 – an upgraded version of the GBU-15 with added GPS/INS guidance, improving the weapon accuracy to 3m

In the early years of the F-15’s career the USAF’s F-15 project office vehemently opposed any notion of using the F-15 in an air to ground role. Despite the lack of USAF interest McDonnell Douglas very quietly continued to work on exploiting the F-15’s air to ground potential and this resulted in a company proposal to build the F-15E, dubbed the “Strike Eagle”. The Strike Eagle was touted as a replacement for the F-111 and the remaining F-4E still in service. As far back as 1978 the USAF commissioned a study called Tactical All-Weather Requirement Study (TAWRS). This looked at the future requirements for USAF tactical strike aircraft and examined McDonnell Douglas’ F-15E proposal versus the F-111F. The study ultimately recommended the USAF procure the F-15E.

McDonnell Douglas subsequently modified the second twin seat TF-15 (which remember was later re-designated the F-15B) prototype into a demonstrator for the F-15E programme. This aircraft was then dubbed the Advanced Fighter Capability Demonstrator and appeared at the 1980 Farnborough Airshow.

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The F-15E demonstrator/development aircraft. Note this aircraft is wearing the USAF’s Euro 1 camouflage scheme, never applied to operational Strike Eagles which all wear a single colour Gunship Grey scheme
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The development aircraft ably demonstrating the Strike Eagle’s bomb capacity, in this case a very heavy load of CBU-52 cluster bombs

In 1981 the USAF launched the Enhanced Tactical Fighter (ETF) programme to develop a replacement for the F-111. McDonnell Douglas entered the F-15E and General Dynamics entered with their F-16XL. The latter was quite a radical development of the F-16 featuring a new cranked delta wing which yielded much better performance than the standard F-16. The ETF programme was later re-named the Dual Role Fighter (DRF) programme to better reflect the requirement for the new aircraft to be able to “self escort” on strike missions. That’s to say they were meant to be capable enough air to air fighters in their own right that they didn’t need additional fighter escort.

You may be surprised to know that the ETF/DRF programme also very briefly considered the Panavia Tornado. This aircraft however, lacked a credible air to air capability and more importantly wasn’t American so it was never a serious contender.

In 1983 the USAF selected the F-15E as the winner. The USAF believed the F-16XL would cost almost twice as much to develop as the F-15E and had less airframe growth potential. The USAF also valued the F-15’s twin engine configuration over the F-16’s single engine.

From lightweight air superiority fighter to heavyweight multirole fighter; the F-16XL is regarded by many to this day as the best fighter the USAF never put into service

The first F-15E flew in December 1986 and the first production aircraft were delivered to the USAF in April 1988. The USAF are the only operator of the F-15E and currently have 220 of the type on strength.

The Strike Eagle features a host of differences over the earlier air superiority Eagles. The Strike Eagle can carry most of the air to ground weapons in the US inventory including:

  • Unguided free fall bombs including the Mk.80 series general purpose bombs and the full range of cluster bombs.
  • Guided bombs such as the Paveway series of laser guided bombs and the JDAM series of GPS guided bombs.
  • Guided glide bombs such as the GBU-15 electro-optical guided bomb, the GBU-39 Small Diameter Bomb (SDB) and the AGM-154 Joint Stand Off Weapon.
  • Air to ground missiles including the AGM-65 Maverick, the AGM-130 (a rocket powered version of the GBU-15), and the latest AGM-158 Joint Air to Surface Standoff Missile (JASSM).
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A USAF F-15E dropping a GBU-28; this is a 5,000lb, laser guided, ground penetrating bunker buster bomb first used in Desert Storm. How far can in penetrate you ask? It can go through 100ft of earth or 20ft of reinforced concrete before detonating

In addition to these air to surface weapons the Strike Eagle also retains the same missile and gun armament of the air superiority Eagles.

The Strike Eagle also features additional avionics to facilitate the new air to ground capabilities:

  • An AN/APG-70 multi-mode radar which adds multiple air to ground radar modes whilst retaining the same air to air modes and improved air-air radar performance versus the APG-63(V)1.
  • Improved navigation systems to allow precise weapons delivery.
  • Low Altitude Navigation and Targeting Infrared for Night. The LANTIRN system allows for all weather, day/night strike operations. It consists of two pods mounted underneath the air intakes. The AN/AAQ-13 navigation pod has a terrain following radar and a fixed infra-red camera which projects an image onto the pilot’s Heads Up Display. The AN/AAQ-14 targeting pod has a high resolution infra red camera and laser designator/rangefinder allowing the crew to locate and designate targets for guided weapons.
  • A new central mission computer with the capacity to handle all of the new avionics and sensors.
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The front (pilot’s) and rear (WSO) cockpit of the F-15E were significantly upgraded from the F-15C
Closest to the camera under the starboard air intake is the AAQ-13 navigation pod. The cylindrical section contains the terrain following radar and just above the nose of this you can see the window for the Forward Looking Infra Red (FLIR) camera. Underneath the port intake is the AAQ-14 targetting pod which contains a gimbal mounted infra-red camera and laser designator. Also note the attachment points for air to ground weapons not present on the F-15C
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The AAQ-13 projects an infra red image onto the pilot’s Heads Up Display, allowing him to “see” in the dark

One notable addition to the Strike Eagle is the Fuel and Sensors Tactical (FAST) packs. These were originally developed for the air superiority Eagle and were used by the Israelis in Operation Wooden Leg. The FAST pack consists of Conformal Fuel Tanks (CFT) fitted to the sides of the aircraft which allow the carriage of an additional 750 US Gallons of fuel. The FAST packs also include the hard points for carriage of air to ground weapons and the attachment points for the LANTIRN pods.

A FAST pack being attached to an F-15E
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This is a good photo showing the FAST packs and where they attach, in this case to an F-15C. Although the FAST packs were originally developed for the F-15C it should be noted the USAF only regularly fits them to its F-15E

When you see an aircraft carrying an external fuel tank (or “drop tank”) that tank carries a penalty in both weight and drag for the aircraft carrying it. As a general rule of thumb only about half the fuel carried in a drop tank is actually useful, the other half is burned counteracting the additional weight and drag. A CFT has a greatly reduced drag penalty so are a considerably more efficient way of carrying additional fuel. The only caveat being you can’t drop a CFT in flight if you want to reduce the aircraft’s weight. They’ve actually become quite popular in recent times with them becoming an option on many contemporary fighters. The RAF’s latest Tranche 3 Typhoons all come with the plumbing and attachment points already in place to add CFTs at a later date.

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A Polish Air Force F-16C Block 52+ with the CFTs clearly evident

The Strike Eagle also has had some very significant structural changes. In order to carry a 10,400kg payload the Strike Eagle’s structure was considerably beefed up and this combined with the addition of a second cockpit resulted in the aircraft’s empty weight being 1,600kg more than an F-15C.

The Strike Eagle was initially delivered with the same F100-PW-220 engines as the F-15C. The heavier empty weight of the F-15E and the fact it would usually be carrying air to ground weapons meant its performance was inferior to the F-15C. However, later Strike Eagles were delivered with the improved F100-PW-229 engine which delivered 22% more thrust than the -220. This meant that an air to air configured Strike Eagle could actually out perform an F-15C. However, in practice the utility of the -229 is it allows the F-15E to handle heavy weapons loads far better than it did with the -220.

The USAF has eight F-15E squadrons of which three are flying -229 powered Strike Eagles.

With over 30 years service now the Strike Eagle has seen numerous improvements and upgrades. We’ve already covered the upgraded engines, and quite a few of those weapons I listed above weren’t around in 1988. As part of the F-15 Radar Modernisation Programme, in 2016 Boeing won a contract to fit AN/APG-82(V)1 AESA radars in 28 Strike Eagles of the USAF. This is part of the same programme which is retrofitting new APG-63(V)3 radars to the F-15C. The AN/APG-82(V)1 features the back end (signal processor) of the AN/APG-79 radar used on the F/A-18E/F Super Hornet with the front end (antennae) assembly of the APG-63(V)3 currently being fitted to the F-15C. The Strike Eagle also received BAE Systems Multi-function Information Distribution System. MIDS is part of NATO’s Link 16 tactical datalink network and allows aircraft, ships, ground units and air defence networks to share tactical information, imagery and voice communications in real time. The utility of this is the Strike Eagle crew are no longer limited to seeing on their displays just what their own aircraft’s sensors can see. They can see the big picture built up from what every Link 16 enabled platform within 300 miles can see.

In 2005 the Strike Eagle received the Lockheed Martin AN/AAQ-33 Sniper Advanced Targeting Pod (ATP). This replaced the AN/AAQ-14 element of LANTIRN. Sniper ATP is a far more capable and advanced system which supports GPS guided weapons and Remotely Operated Video Enhanced Receiver. ROVER was developed during the war in Afghanistan and represents a quantum leap in co-ordination between ground units and air units. ROVER allows near real-time display of the sensor image from an aircraft on a ground terminal, and the operator of the ground terminal can mark hostile targets, friendly forces and areas of interest which are then displayed to the crew of the aircraft. The man on the ground can even take control of the aircraft’s targeting pod. The initial ROVER ground terminals were very large and needed to be carried on a Humvee, within a short space of time new ones became available which could be carried in a back pack, and the latest variants are hand held. Needless to say the ability for a Forward Air Controller (FAC) embedded with ground troops to see the exact same picture the aircrew above see through their sensors, and for that FAC to be able to mark targets and friendly forces on that picture which is then sent back to the air crew is a pretty big thing.

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Underneath the port air intake you can see the new Sniper ATP which has superceded the AAQ-14. Also note all the hardpoints for attaching air to ground weapons on the F-15E
The newer ROVER terminals are hand-held, essentially and iPad which lets you call in an airstrike
Suffice to say this has provided nothing short of a quantum leap in Close Air Support and co-ordination between the blokes on the ground and the pilots in the air above

The Strike Eagle made its combat debut during Desert Storm. Early on Strike Eagles were used to destroy fixed Scud launch sites. Later on they were heavily involved in the infamous “Scud Hunts” over western Iraq searching for the elusive mobile launchers which were firing on Israel. Strike Eagles were also used against more heavily defended targets and these resulted in the Strike Eagle’s two combat losses of the war, both lost to surface to air missiles. There were several instances of Strike Eagles engaging Iraqi aircraft but the only air to air kill of the Strike Eagle in Desert Storm was a very unusual one. Responding to a request for assistance from Coalition Special Forces, a pair of Strike Eagles engaged five Iraqi helicopters. One of them dropped a 2,000lb GBU-10 laser guided bomb on a Hind helicopter as it was hovering and unloading Iraqi troops. The bomb struck its target and the helicopter was destroyed.

Strike Eagles also participated in Operation Southern Watch and Operation Northern Watch. In one incident during ONW a flight of Strike Eagles observed Iraqi helicopters attacking Kurdish refugees. The rules of engagement did not allow the Strike Eagles to open fire so instead the pilots carried out several high speed passes very close to the helicopters in an attempt to create strong wake turbulence and attempted to blind the Iraqi helicopter pilots with their laser designators. One Iraqi helicopter crashed as a result but after this incident the American pilots were forbidden from flying below 10,000ft. Strike Eagles also saw action in Operation Desert Fox.

The Strike Eagle saw extensive service during the various NATO operations over the Balkans in the 1990s, culminating in Strike Eagles flying the first strikes against Serbian air defence network targets during Operation Allied Force in 1999.

The aircraft was once again back in action during Operation Enduring Freedom over Afghanistan. One notable achievement during OEF was when a flight of F-15Es struck multiple Taliban targets over a period of fifteen hours and carried out twelve aerial refuellings, making it the longest fighter combat sortie in history.

In 2003 during Operation Iraqi Freedom Strike Eagles were used to destroy command and control targets in Baghdad and were credited with the destruction of 65 aircraft on the ground and destroying over 60% of the Iraqi Republican Guard formations. One Strike Eagle crashed whilst supporting Special Forces operations near Tikrit, killing both crew. It is believed the aircraft was most likely brought down by anti aircraft fire.

In 2011 the Strike Eagle was called upon once again during Operation Odyssey Dawn in Libya. Eighteen Strike Eagles were deployed in support of the operation and one crashed in rebel held territory near Benghazi. The aircraft departed controlled flight and entered an unrecoverable spin during a combat egress maneouvre. Both crew ejected and were rescued with only minor injuries.

More recently Strike Eagles have been used in Operation Inherent Resolve to attack IS targets in Syria and Iraq, and also strikes against IS targets in Libya.

The F-15E Strike Eagle has been used as a basis for several export models, all of which are currently in service:

F-15I Ra’am (Thunder) – This is a Strike Eagle derivative used by Israel. It differs from the baseline US F-15E in having bespoke Israeli avionics and a downgraded AN/APG-70I radar where the high resolution ground mapping functions produce a lower resolution image than the AN/APG-70 used by the USAF. The crew have an indiginous Israeli helmet mounted sighting systems which allow them to cue sensors and air to ground weapons on to a target. Israel is planning to replace the AN/APG-70I radar with a new locally developed AESA radar.

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F-15I Ra’am

F-15K Slam Eagle – This is a version developed and exported to South Korea with significant South Korean industrial involvement. These aircraft have the AN/APG-63(V)1 radar which is mechanically scanned but has the same back end as the AN/APG-63(V)3 thus allowing the radars to be upgraded to AESA at a later date simply by replacing the antenna. They also feature an infra-red search and track system for airborne targets and have an improved electronic warfare and self protection suite. The crews have the Joint Helmet Mounted Cueing System (JHMCS) and the aircraft are compatible with the AGM-84K SLAM(ER) stand-off ground attack missile, the AGM-84H Harpoon Block II anti-ship missile and the German/Swedish KEPD 350 cruise missile. The F-15K has been ordered and delivered in several batches, depending on the batch they are powered by the F100-PW-229 or F110-GE-129 (mentioned below).

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F-15K Slam Eagle

F-15SG – Broadly similar to the F-15K this version was developed for the Republic of Singapore Air Force.

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F-15SG

F-15S – Developed for Saudi Arabia these are virtually identical to the USAF F-15E but the like the Israeli Ra’am the radar is downgraded in a similar manner.

F-15SA – A newer version developed for Saudi Arabia. Changes include a new digital fly by wire system, the AN/APG-63(V)3 AESA radar, a new electronic warfare and self protection system, an infra-red search and track system and a new cockpit.

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F-15SA; currently the most advanced Eagle in production

F-15QA – The latest variant of the F-15 developed for Qatar and contracts signed just this year. Broadly similar to the F-15SA.

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Both the F-15SA and F-15QA feature a new cockpit

The F-15SA, F-15QA, F-15SG and the latest batches of the F-15K are powered by the General Electric F110-GE-129 engine which has slightly more thrust than the Pratt & Whitney F100-PW-229.

In 2010 Boeing (remember, they took over McDonnell Douglas in 1997) offered the F-15SE, or “Silent Eagle”. This was a development of the F-15E which had various features designed to reduce the aircraft’s radar signature; extensive use of radar absorbent materials, internal weapons carriage and the vertical tails canted outwards. It was marketed towards Israel, Japan, South Korea and Saudi Arabia. The former three all selected the F-35 and the latter opted for the F-15SA instead.

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The Silent Eagle, thus far it has not existed beyond this mock-up

So what does the future hold for the F-15? In the latter part of the Obama administration defence cuts were really starting to bite and there was very real consideration being given to retiring the F-15C from the USAF. However, President Trump has not only reversed those cuts but is increasing defence spending so it may be the F-15C is going to be around for a while longer yet. The USAF intends to keep the F-15E in service until the 2030s and there is currently no replacement for it on the horizon. What is interesting is the persistent rumours that Israel had its arm twisted into procuring the F-35 when it would have preferred to get something based on the F-15SE. This perhaps isn’t so easily dismissed given how they’ve recently hoovered up a number of 40 year old second hand US Air National Guard F-15D and are busy refurbishing them. Maybe they know something we don’t.

The South Koreans have said they intend to operate the F-15K until the 2060s, at which point the F-15 will have been flying for 90 years.

Not a bad innings, I suppose.

As a final addendum, you may be interested to hear that in the early 1980s our very own Ministry of Incompetent Twats…. sorry, Ministry of Defence briefly looked at the possibility of procuring the F-15 for the RAF to replace the Phantom. It was quite rapidly dismissed as it was very expensive, there wasn’t much prospect of British industrial involvement and it was thought the F-15 might not be the optimal solution for shooting down Soviet long range cruise missile carriers trying to break through the GIUK Gap. In the end we developed the Tornado ADV instead… which is perhaps a story for another time.

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The UK MOD selected the Tornado Air Defence Variant (ADV) for its fighter requirement. Initially entering service in 1985, the Tornado F2 was a scandalous embarassment. However, it did eventually mature into the Tornado F3 pictured here, which upon its retirement in 2011 was arguably the best interceptor in any Western air force

 

© Æthelberht 2018
 

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