The Eagle

Part 1 - Genesis of the F-15

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A USAF F-15C loaded with a mix of AIM-7 Sparrow, AIM-120 AMRAAM and AIM-9 Sidewinder missiles

In my last mini-series of articles we had a look at the Boeing 737. I hope you came away from that with a better appreciation of what a remarkable machine it is and a testament to the ability and vision of the team who designed it. However, it is still just an airliner. A bit pedestrian in its performance and not particularly glamorous or sexy, especially when you’re crammed into a Ryanair 737 and the cabin crew are trying to sell you scratch cards.

So for this series we’re going to go a lot faster, a lot louder and with a lot more G. We’re going to take a look at an aeroplane which you definitely won’t be hopping on to for a weekend break in Prague.

The McDonnell Douglas F-15 Eagle.

Following its introduction in 1976 the Eagle was the USAF’s premier air superiority fighter for the next 29 years. It carved out for itself a reputation as the most formidable fighter of the Cold War and the decade or so that followed. It has racked up a kill to loss ratio of 104:0 and is considered by many to be the ultimate “MiG Killer”. Now in the twilight of its career as an air superiority fighter the multi-role strike version will soldier on for many years to come and remains a formidable combat aircraft.

The Eagle’s story is quite a long and sometimes convoluted one. So bear with me as we go back over fifty years to 1965…

Herding Cats (aka Joint Programmes)

The Vietnam War is heating up and American forces have been well and truly blooded. The US Air Force (USAF) is thinking about procuring a new fighter bomber to replace the F-100 Super Sabre and the US Navy (USN) want a light bomber to replace the A-4 Skyhawk and A-1 Skyraider. Robert McNamara is the US Defense Secretary. McNamara isn’t happy with the state of affairs when it comes to defence procurement. He thinks a lot of time and money is wasted in the services each pursuing their own individual procurement solutions to common requirements. McNamara advocates “joint” programmes where the services develop common procurement solutions to meet their needs. The most (in)famous of these joint projects was the Tactical Fighter Experimental (TFX) programme began in 1961 where McNamara ordered the USAF and USN to develop a common airframe to meet the former’s requirement for a low level strike aircraft and the latter’s requirement for a carrier borne fleet defence interceptor.

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TFX was ultimately realised as the F-111 Aardvark but the USN bailed out of the programme

So it was in this context that McNamara directed both the USAF and USN in January 1965 to pursue a common airframe to meet their requirements for a new tactical fighter bomber. There was a slight problem. It’s hard enough getting the USAF and USN to agree on the time of day, let alone a common airframe. The USAF wanted something that was primarily an air-air fighter with a secondary ground attack capability. The USN however, just wanted a straightforward bomb truck that could take off from a carrier, fly to where the communists are and drop high explosive on their heads.

The USN were already sizing up the LTV A-7 Corsair II to fit their requirements, but it’s lack of any credible air-air capability left it a non-starter for the USAF. Likewise some in the USAF were giving consideration to a solution based on the Northrop F-5 Freedom Fighter but the F-5 wasn’t carrier capable.

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The A-7 Corsair II. When the pointy end is at the back you know it’s not going to make a very good fighter – it was however, a rather good light bomber and ground attack aircraft. It was powered by a single Allison TF41 engine which was actually a license built Rolls-Royce Spey

In February 1965 it was suggested the USAF procure either the F-5 or A-7 for the ground attack role but develop a new, higher performance type for the air superiority role called F-X. Over the rest of 1965 this slowly became the preferred course of action for the USAF as the chorus calling for F-X grew larger and louder. Design studies for F-X began and these focused on a design which placed manoeuvrability over speed. In November the USAF ordered the A-7 for the ground attack role which pretty much sealed the case for developing F-X.

The requirements were finalised and a request for proposals was issued to thirteen manufacturers in December 1965. Of those thirteen, eight responded with proposals for designs which were all in the 60,000lb weight range and had a thrust to weight ratio of 0.75:1. The USAF rejected all of these proposals as unsuitable for an air superiority fighter.

Why did the USAF need a new air superiority fighter?

Now is a good point to stop and talk about what was actually happening in the skies over Vietnam.

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The F-100 Super Sabre was typical of the 1950’s Century Series fighters the USAF took to Vietnam

The aerial combat experience over Europe during WW2 pointed to the critical advantage being held by the combatant who could fly faster (and preferably higher as well). This experience was reinforced over Korea when the F-86 Sabres tangled with the MiG-15. The USAF procured an entire generation of fighters developed along the concept of going bloody fast (and not much else). These were known as the Century Series. The pinnacle of the Century Series type thinking was actually a fighter designed by McDonnell for the US Navy and quickly adopted by the US Air Force. In 1962 the two services adopted a common system for designating aircraft and what the USN called the F4H Phantom II and the USAF called the F-110 Spectre became known as the F-4 Phantom II.

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The first F-110 Spectre delivered to the USAF in 1962. You probably know it by a different name

When it became entangled in Vietnam the US had what it believed was the most advanced and capable fighter in the world with the F-4. It was very, very fast and was equipped with what was then a state of the art radar and an all-missile armament consisting of the AIM-7 Sparrow and AIM-9 Sidewinder. The F-4 would detect the enemy with its powerful and sophisticated radar and blast them out of the sky with its missiles before the enemy even saw the F-4.

Well, at least, that was the plan. No plan, as they say, survives first contact with the enemy.

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A USAF F-4C – the Charlie model was the one used by the USAF in the early war years and was followed by the Delta, then both were ultimately superseded by the much improved Echo model. The USN started the war with the carrier capable Bravo model and ended it with the improved Juliet

The technology simply didn’t work as advertised. Modern fighter radars utilise huge amounts of signal processing to present the crew with an easily understood synthetic picture. The radars used on the Vietnam era Phantoms, such as the AN/APQ-100 used on the F-4C only had basic signal processing and presented an almost raw radar picture which required a very competent man in the back seat to make any sense of. What’s more, the Vietnam era Phantom radars had no “look down” capability. That’s to say they were unable to pick out a low flying target against the clutter of radar returns from the ground.

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This is what an F-4 crew in Vietnam would have seen on their radar scope
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This is a more modern display which would have been common in the 1980s and 90s once computer power had increased enough to provide advanced signal processing

When the Phantom crew did find a target they found their missiles left a lot to be desired. The early Vietnam era Sparrow and Sidewinders were quite frankly, utter shit.

During its development the radar guided AIM-7 Sparrow had achieved a Pk (probability of kill) of 80-90%. In operational testing that fell to 50-60%. In actual combat over Vietnam the Pk fell to 8-10% depending on the actual missile variant in use. The AIM-7 in particular was plagued by very high malfunction rates (the electronics were especially susceptible to atmospheric moisture) and further crippled after some early instances of friendly fire resulted in the Rules of Engagement being changed so Phantom crews had to visually identify their targets before firing. In a single stroke this destroyed the Phantom’s biggest advantage of being able to engage at longer ranges where the North Vietnamese MiGs could not fire back.
The infra-red guided AIM-9 Sidewinder didn’t fare much better. Again depending on the variant used the actual real life combat Pk of the early Vietnam era Sidewinders was 12-19%.
When the USAF introduced the F-4D with the AIM-4 Falcon missile in 1967 that particular missile achieved an utterly miserable Pk of 9%. So unpopular and maligned was the AIM-4 that the legendary Colonel Robin Olds ordered his entire F-4 wing be re-wired to carry the AIM-9 instead of the AIM-4, which at the time was an unauthorised modification to the aircraft.

It was found that many crews were firing the missiles outside of their very limited launch parameters. For example, the AIM-9B could only be launched under 1G otherwise the guidance system would malfunction. Likewise its infra-red seeker would only acquire a target from a near dead-astern position and even then would sometimes prefer to go after the Sun rather than the MiG.

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AIM-7 Sparrow missiles ready to be loaded onto F-4Cs at Cam Ranh in 1967
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AIM-9 Sidewinders on the deck of USS Hancock in 1967
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An F-4D carrying four AIM-4 Falcon missiles on the inner wing pylons. Also note the four AIM-7 Sparrows carried under the fuselage

Prior to Vietnam US doctrine had decreed now the era of the radar equipped and missile armed fighter had arrived the old fashioned dogfight was a thing of the past. As such the Phantom was designed without a gun and the crews were not trained very well in Air Combat Manoeuvring (ACM – military parlance for “dogfighting”). The technical shortcomings outlined above combined with the restrictive Rules of Engagement meant that Phantom crews often found themselves tangling at close quarters with North Vietnamese fighters like the MiG-17. On paper at least, the MiG-17 was an obsolete type totally outclassed by the Phantom. It was subsonic, only carried a cannon armament and only had a small target ranging radar linked to the gunsight. The MiG however, was much smaller, lighter and had a considerably lower wing loading and at speeds below 400 knots would literally fly rings around the Phantom which by contrast was big, heavy, highly wing loaded, and lacked a sufficient thrust to weight ratio to be an effective dogfighter.

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Soviet fighters like the MiG-21 were supposed to be obsolete and no match for the F-4
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A North Vietnamese MiG-17 photographed from the cockpit of an F-4 – the Phantom was never, *ever* designed to get this close and tangle with more agile and nimble fighters, yet this was the reality encountered over Vietnam

The result of all of the above, as you might expect was pretty bad for the Americans. In the early Vietnam era the kill to loss ratio in air combat was 2:1; totally unacceptable for the Americans flying their state of the art fighters against what were believed to be obsolete and outdated Soviet designed fighters.

It didn’t take long for both the USAF and USN to begin some serious soul searching in order to work out what had gone wrong. In 1966 the USAF began Project Red Baron (which was followed up by Red Baron II in 1973 and Red Baron III in 1974). This involved a small team of officers conducting extensive interviews with every aircrew who had engaged in aerial combat with NVAF MiGs and collating the information together into a final report. Likewise the USN commissioned the Ault Report in 1966 to find out why aerial combat performance was so poor.

Ultimately Project Red Baron led to massive institutional changes in USAF tactical aviation; the foundation of the Aggressor programme, the now famous Red Flag exercises in Nevada and the highly classified Constant Peg programme where American fighter aircrews were given the opportunity to train against clandestinely acquired MiG-17, MiG-21 and MiG-23 flown by hand-picked instructors.

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A MiG-21 F-13 of the 4477th Test & Evaluation Squadron in flight over the Nevada desert – these early MiG-21 models were acquired clandestinely from Indonesia after being recovered from a swamp
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Members of the 4477th TES pose in front of a MiG-21 F-13 inside one of their hangars at Tonopah Air Force Base circa mid-1980s. Note the mixed unit consisting of USAF, USN and a USMC pilot, these were the hand-picked elite of American fighter pilots. The female front row 3rd from left was the squadron’s intelligence officer
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4477th TES maintainers pose in front of the Kenworth truck they purchased specifically to haul MiG spare parts across the country

The Ault Report led to the foundation of the Navy Fighter Weapons School, more commonly known as Topgun and ultimately resulted in James Tolkan threatening Tom Cruise with rubber dog shit, and the tragic and untimely death of Goose in 1986.

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Do not mess with this man
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RIP Goose

As the war progressed both the USN and USAF began receiving new and updated models of the F-4 and the missiles, and the F-4 finally got a gun. From 1969 the first Topgun graduates began filtering into front line USN squadrons in Vietnam and between 1969 and 1973 the USN’s kill to loss ratio rose to 6.5:1. During the same period the USAF’s kill to loss ratio rose slightly to 2.4:1, although it should be noted that 55% of the aerial combat losses sustained by the USAF during this period were of aircraft engaged in air-ground missions. When we consider the kill to loss ratio of aircraft engaged in MIGCAP (i.e. ones specifically looking to shoot down MiGs) the USAF ratio rises to 14.3:1 in this period versus the USN at 5:1.

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In 1972 pilot Lieutenant Randall H. Cunningham and RIO Lieutenant William P. Driscoll became the US Navy’s only two flying aces of the Vietnam War. Both were Topgun graduates>
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F-4J “Showtime 100” – Cunningham and Driscoll’s mount when flying with VF-96 from USS Constellation in 1972

By the end of the Vietnam War the final kill:loss tally in air combat for the F-4 was as follows:

US Air Force: 108:33
US Navy: 40:7
US Marine Corps: 3:1

Or a total of 151:41 which gives a kill:loss ratio a midge’s dick below 3.7:1

Not good enough. Must try harder.

By the way, I highly recommend the book “Red Eagles” by Steve Davies which not only tells the story of the Constant Peg programme and the 4477th Tactical Evaluation Squadron, but also explains how the Red Baron reports led to the Aggressor programme and the institution of the Red Flag exercises. An excellent read for aviation history buffs.

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Red Eagles – America’s Secret MiGs by Steve Davies, Osprey Publishing

Meanwhile In the Soviet Union

Our communist pals hadn’t been idle. They too had been watching developments in Vietnam with interest and were making two new fighters of their own. The MiG-23 first flew in 1967 and the MiG-25 first flew in 1964. Both entered service in 1970.

NATO gave the MiG-23 the reporting name Flogger and Western analysts believed it was quite likely superior to the Phantom.

The MiG-25 was given the reporting name Foxbat and caused NATO to collectively crap its pants. NATO believed the Foxbat was an agile Mach 3 capable air superiority fighter far superior to anything NATO had at the time.

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The MiG-25 “Foxbat” – the fighter that made NATO wet itself in the early 1970s

Aviation and Cold War history buffs will know that in 1976 Soviet pilot Viktor Belenko defected to Japan with his MiG-25P, and after pulling it to pieces for a bloody good look and debriefing Belenko the Americans came to the conclusion that the MiG-25 was nowhere near as potent as they had thought and was in fact a bit of a one trick pony. It was about as agile as a drunk elephant on an ice skating rink. Whilst it was technically capable of achieving Mach 3 in doing so it would wreck its engines and they’d need to be replaced before the aircraft could fly again. The MiG-25 was very good at flying very fast in a straight line and absolutely bloody useless for anything else. Remember though, nobody in the West knew this until 1976.

So it was the development of these two new Soviet fighters, and the MiG-25 in particular had a major impact on the development of F-X.

Disagreement

Back in the States the USAF was still arguing amongst itself over the form F-X should take. Some factions wanted a multi-role fighter bomber whereas other factions wanted a pure air superiority type which could go toe to toe with the new and much vaunted MiG-25. Yet another faction was saying that F-X is a mistake altogether and what’s needed in a small, light, cheap daytime air superiority fighter that stresses agility and high thrust to weight ratio.

If you remember earlier we talked about the joint TFX programme which was developing the F-111B for the USN as a fleet defence interceptor. The USN was simultaneously looking at designs for a programme called VFAX which would deliver a smaller multi-role fighter to complement the F-111B. Some in the USAF feared that they would be forced to ditch F-X and procure VFAX (cue horrified gasps and shrieks… “A Navy plane!”). In 1968 the various factions put their differences aside and settled on a dedicated air superiority type for F-X.

As it turned out in the same year the USN successfully extricated itself from the TFX/F-111B which was turning into a proper dog’s dinner. They were given the green light to pursue their own independent programme for a new fleet defence interceptor. Both TFX and VFAX were dropped by the USN and the VFX programme was started which would go on to deliver the Grumman F-14 Tomcat.

Following the agreement to pursue a pure air superiority fighter for F-X, in September 1968 the USAF issued a request for proposals to General Dynamics, North American Rockwell, Fairchild Republic and McDonnell Douglas. The request called for a single seat, twin engine fighter with a maximum take-off weight of 40,000lb, a maximum speed of Mach 2.5 and a combat thrust to weight ratio of 1:1.

The General Dynamics submission was quickly eliminated and the remaining three manufacturers were asked to submit more detailed technical proposals. On 23rd December 1969 the McDonnell Douglas proposal was selected for F-X.

The Eagle had hatched.

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The prototype F-15 Eagle on its first flight in 1972

In the next part we’ll take a look at the features of the F-15 Eagle, what it brought to the table and how it differed from the earlier F-4 Phantom. We’ll also cover how the air superiority variants evolved through the late Cold War and the years that followed the collapse of the Soviet Union through to the present day.

By the way…. If any of you are wondering why earlier in the article I referred to the F-4 as the “Phantom II” it’s because the F-4 was actually the second McDonnell design to bear the Phantom name. The first one was the FH Phantom which first flew in early 1945 and became the first American jet powered aircraft to land on an aircraft carrier. It had a brief career between the end of WW2 and the beginning of the Korean War. You’ve never heard of it before because it was a bit shit.

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The McDonnell FH Phantom – slower than the best piston engine fighters of its day it nevertheless brought jet powered flight to the US Navy’s carrier decks

 

© Æthelberht 2018
 

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