Second Generation Jets — The Need for Speed

In warfare, time is always a paramount consideration. The general rule appears to be if you can operate at tempos above that of your enemy, you gain and hold the initiative.

In the Second World War time was critical as it gave the defenders the opportunity to climb to a suitable altitude from which to gain speed and engage the enemy. However; as jet fighters started to evolve, tactics became driven more by the closing speeds between an air defender and an incoming threat.

If the enemy aircraft was thought to be carrying a nuclear warhead, it became even more important to get airborne and attack the enemy as far away as possible from home territory.

During the Cold War this was not too difficult over the North Sea and the polar wilderness of the Arctic Sea; in Germany, however; the timings involved were very reminiscent of what happened in the Second World War: with Quick Reaction Alert (QRA) flights needing to be capable of responding at very short notice to threatened incursions by Warsaw Pact aircraft.

Time pressures and the limitations of ground-based radar systems would lead to the introduction of airborne early warning systems, such as the Shackleton, to extend the radar coverage out even further to address the low-flying high-speed threat from Soviet bombers.

Small Steps

The development of the second generation of fighter jets — with designers trying to eke out slight performance enhancements over the last version — provided a microcosm of what was to come on a wider scale as the two main super-blocs sought to gain an advantage.

What had started in the first generation fighter jets, such as the Meteor; as a series of in-service enhancements to the airframe, engine and equipment was to be continued into the second generation.

Developments in electronics and aerodynamics were combined with lessons emerging from the Korean War to define the next generation of fighter jets. Analysis developed by USAF Colonel John Boyd into the reasons why the F-86 Sabre had proven so successful in combatting the MiG-15 were pivotal in shaping the new designs, many of which simply skipped a generation.

For some countries emerging from the ravages of the Second World War, buying British, Soviet or American fighter jets was simply a stop gap until their own national development programmes gained enough experience. We had now reached the point at which the number of states able to build their own fighter jets started to grow really quickly.

“If it Looks Right…”

Fighter jets are not immune from being given human traits. It is something we as human beings often do to inanimate objects. The Hawker Hunter — often described as being beautiful — is a case in point.

The first time it flew with the Black Arrows aerobatics team it engendered the idea of being an aircraft that enthusiasts and pilots alike could fall in love with very easily….The phrase «If it looks right, it’ll fly right» could have been written about the Hunter.

Its designer Sidney Camm had sought to build on the straight-winged Hawker Sea Hawk that had failed to gain any interest from the Royal Navy, By sweeping the wing back by 35°, the Hawker design team showed they could also produce an aircraft that was capable of significantly improved speeds and the P1052 prototype took that first important step when it first flew on November 19, 1948.

Several other design iterations were to follow, all of which contributed to the development of the P1067, which was to become the Hunter.

It was to be powered by both the next generation of jet engine emerging from Rolls Royce (the Avon turbojet) or the Armstrong Siddeley Sapphire 101. Both engines, however: suffered initial teething problems, but development of the Avon 200 series was to provide a solution with the F.6 variant of the aircraft being equipped with the Avon 203.

The Hawker Hunter was designed to meet the requirements laid out by the British Air Ministry in a Specification named F.43/46 covering the requirements for a daytime jet-powered interceptor:

This was revised in 1948 and re-issued as Specification F.3/48 that envisaged a fighter capable of a maximum speed of 629mph at 45,000ft and armed with four 20mm or two 30mm cannon — the uncertainty of the cannon calibre reflecting a concern over just what it would take to shoot down Soviet bombers that were in development.

The introduction into service of the Hawker Hunter was greeted with great enthusiasm by the ground crews who would ensure its operational serviceability, Arguably it was the first modular fighter: with key components easily accessible and replaced, and the more than 2,000 built would go onto serve in 22 air forces around the world.

Durability

Even though its impressive speed capabilities were rapidly overshadowed by the development of even faster jets, the Hunter would show its operational durability by going on to serve in the ground attack role, for which arguably it was better suited.

It would also perform significant combat roles in far flung places across the globe, such as Oman, but for the RAF, the air interceptor role performed by the Hawker Hunter was soon to be taken over by an aircraft that in one step changed the character of future air warfare. That was the English Electric Lightning.

Lightning Force

The Lightning was one of the most iconic of all the second generation fighter jets (some would argue of all jets) and, as its name suggests, it was simply designed to get to its target quickly.

This was the nearest thing to a manned rocket and it instilled in those that flew it or saw it flying a sense of awe. Its evocative name still resonates with airmen and explains, in part, why the new F-35 Joint Strike Fighter aircraft will be called Lightning II in RAF service.

To see an English Electric Lightning take off, stand on its tail and climb out of sight was quite a spectacle.

At the Royal Aircraft Establishment at Farnborough a single variant of the aircraft was used by the Engineering Physics Department for flight tests; its swept wing design capable of climbing at an initial rate of 50,000ft/min. The sheer power of the Avon engines in re-heat would make the ground reverberate.

The Lightning entered service in 1960 and replaced the Hawker Hunter and Gloster Javelin in the air interception role, with the first examples joining 74 Sqn. It was to be the start of a career that would span 28 years and would also see the aircraft in service with the Kuwaiti Air Force and the Royal Saudi Air Force.

Step Change

At Mach 2.0 in level flight, the Lightning was more than twice as fast as the Hunter and represented a step-change in the RAF’s air-to-air interdiction capabilities. No previous step-change in flight performance had ever occurred of this magnitude and it was all driven by the concerns over time.

It could also reach altitudes in excess of 60,000ft, but this dramatically improved performance came at a cost. The first version of the Lightning had quite limited range and a typical supersonic dash to intercept a Soviet Tu-95 ‘Bear’ bomber would last 35 minutes and cover a range of over 800nm. It was therefore only able to defend a relatively small area, but rapid developments in air-to-air refuelling saw the Lightning quickly receive a probe so that it could take on extra fuel, enabling it to also mount standing patrols at times of increased tension, such as during the Cuban Missile Crisis.

From its inception on the draftsmen’s table, the English Electric Lightning was conceived as an aircraft that would only operate in the air defence environment. Its mission was simply to fly as fast as possible towards the enemy; turn, get on their tail and fire one of the two heat seeking Fireflash missiles. These were the first generation of passive seeker head missiles that could home in on the heat exhausts from Soviet bombers, but they had to be fired from a location behind the target. If the missiles failed, the pilot of the Lightning could use the two 23mm Aden guns that were also fitted to the aircraft.

Radar Interceptor

The Lightning also carried a Ferranti AI 23 Airborne Interceptor Radar and Pilot Attack Sight System (AIRPASS) radar system. This, however; only had a range of around 30 miles against a large target like the Soviet Tu-95 bomber and with the Lightning being flown by a single pilot, he had to also interpret the radar system — something that required considerable mental and physical dexterity.

The pilot would be flying the aircraft with the right hand while looking into the radar scope through a rubber hood and operating it using the left hand. In many ways the Lightning pilots were the first generation of virtual warriors, deciding on how to fly the aircraft based on the information they were able to gather from the radar display. Considerable mental agility was also required to relate the situation from the 2D screen into a real 3D world. Such was the degree of concentration required that some pilots often found themselves flying an intercept inverted, unaware that the aircraft had rolled.

American Developments

American designers had also started to produce their own second generation of jet fighters. Historical analysis attributes ten aircraft to the catalogue of second generation fighters and entries include aircraft developed by all the famous manufacturers of the day. McDonnell Aircraft contributed their FI0I Voodoo, Grumman created the F-II Tiger and Douglas Aircraft gave the US Navy the F4D Skyray.

But of all the entries in the notional catalogue of American second generation fighters, the Vought F-8 Crusader is arguably one of the most interesting. So successful was the design of the airframe that it appeared in 18 different production versions and was also the first naval aircraft to fly at speeds above 1,000mph.

Built to operate from aircraft carriers, it was designed to bring air superiority over carrier battle groups. The aircraft had been designed by a team led by John Russell Clerk to meet a specification for the next generation of naval fighter requiring a jet capable of flying at Mach I.2 climbing at 25,000ft/min. However as a carrier-based aircraft it would also have to land at speeds around I00mph.

Variable Incidence

The Vought design team tackled these two extremes of the flight envelop by introducing a novel variable incidence wing into the aircraft. By hinging the swept wing at its trailing edge, the entire wing could be moved by seven degrees. Although this introduced additional weight into the airframe, it was seen to provide the solution required as it enabled greater lift to be maintained at lower speeds whilst not restricting the angle of attack, which would cause problems for carrier-based jets. It also meant that the wing had to be mounted on top of the fuselage — an unusual configuration for a fighter jet.

The aircraft proved itself in carrier operations although the position of the nosewheel did cause some pilots a few disconcerting moments. As they moved around the flight deck of carriers, they often found themselves feeling as if they were about taxi into the sea.

Despite the low drag canopy, the pilot had excellent all-round vision required for air-to-air engagements, something that had been a serious problem for the Crusader’s predecessor — the F7U Cutlass.

In its initial configuration, the Crusader was also the last American fighter equipped with guns as its primary weapon system but in later variants it carried its own special version of the ubiquitous Sidewinder missile and was equipped with a powerful radar system for tracking inbound threats.

During its service over Vietnam, it flew from the smaller Essex-class aircraft carriers and achieved a kill ratio of 19:3 shooting down I6 MiG-I7s and 3 MIG-2Is. Ground attack operations involving the F-8 Crusader; however; were more costly with 80 aircraft lost to ground fire or surface to air missiles. The last Crusader was retired from service in the French Navy in 2000.

While quite different to the Lightning, the Crusader also evoked similar emotional responses from those that flew it. The phrase «a joy to fly» was one that typifies the reaction from pilots who had the privilege of flying the F-8.

Area Rule Deltas

Another innovation of the period arose from advances in aerodynamics known as the Transonic (or Whitcomb’) Area Rule. This arose from the recognition of exactly how airflow changed over a wing as it approaches the speed of sound.

Richard Whitcomb’s interest in the phenomena had been piqued by problems he had seen with the performance of another second generation jet, the Convair F-102. The first variant of this fighter experienced a level of performance that was well below its expected capabilities and given its primary mission was to intercept Soviet bombers taking the polar route to attack America the problem needed to be solved.

The F-102 was based on a delta wing configuration and was able to fly to 54,000ft. Its wing configuration provided great lift with low-levels of wing loading that gave the aircraft good manoeuvrability but its initial poor performance was a cause for concern.

It is important to remember that aerodynamicists of the age had no computers on which to run high fidelity models of the airflows over the surface of the wing; they needed to imagine the problem in their own heads. Today’s designers rely on advanced graphic systems to help visualise the problems which, in part, explains why so many aircraft look alike nowadays.

For the Convair delta, a simple modification to the airframe that added more bulk to the rear reduced the problems caused by transonic flows and provided the basis of another iconic second generation fighter; the Convair F-106A Delta Dart.

The F-106A also benefited from having a larger engine and a top speed that was nearly twice that of the F-102A. But its acceleration was insipid with the first models taking 4 1/2 minutes to accelerate from Mach 1.0 to Mach 1.7 at its operational ceiling. To reach Mach 1.8 took a further 2.8 minutes. Both the F-102A and the F-106A were to serve the USAF admirably They and their counterparts in the second generation of fighters were to provide the kind of fast reaction capability that Air-Vice Marshall Keith Park could only dream about.

The era of the second generation of fighter jets was also to be a time when the relative advantages of the West in engine design, airframe structures and aerodynamics were to be narrowed. For the next generation of fighter jets — the third — it would be in the area of electronics where the west to try to re-establish its relative advantage.

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