The English Electric (BAC) Lightning

During the 1950s, the British English Electric (later BAC) firm developed Britain's first (and in a sense last) operational Mach 2 fighter. A powerful and impressive aircraft that was restricted by limited endurance and armament, it went into service as an "interim solution" in the early 1960s, only to finally be retired from first-line roles in 1988. This document provides a history and description of the Lightning.

English Electric (BAC) Lightning Origins: P.1A & P.1B

Although the performance increases of jet-powered aircraft introduced towards the end of World War II were breathtaking, there were those at the time who believed that much more was possible. As far back as 1943, the British Ministry of Aircraft Production had issued a specification designated "E.24/43" for a supersonic experimental aircraft that would be able to achieve 1,600 KPH (1,000 MPH). Miles Aircraft came up with a concept designated the "M.52" and received a contract to build the machine.

With the end of the war risk-taking was less acceptable, and the M.52 project was cancelled in early 1946. In its place, a team at Vickers under the well-known Barnes Wallis was to build remote-control models, basically what would now be regarded as experimental unmanned aerial vehicles (UAVs), to explore supersonic flight. That was not in itself a bad idea, since in more recent decades UAVs have often been successfully used to evaluate unconventional aircraft configurations at low cost, but Vickers fumbled the program. The American rocket-powered Bell X-1 was the first aircraft to officially break the sound barrier in level flight, on 14 October 1947.

Britain had lost a chance to be at the leading edge in supersonic flight studies, but the matter wasn't dropped either. Beginning in 1946, a design team at English Electric (EE) under W.E.W. "Teddy" Petter began design studies for a supersonic fighter, leading to award of a Ministry of Supply (MoS) contract in 1947 under specification "ER.103" for a design study on an experimental aircraft that could achieve Mach 1.2.

The MoS liked the EE concepts, and in early 1949 awarded the company a contract under specification "F.23/49" for two flying prototypes and one ground-test prototype of the "P.1". The P.1 was defined as a supersonic research aircraft, though the design had provisions for armament and a radar gunsight. It incorporate advanced and unusual design features, such as twin turbojet engines mounted one above the other to reduce aircraft frontal area; and strongly swept wings, with the wingtips at a right angle to the fuselage, giving a wing configuration somewhat like that of a delta wing with the rear inner corners cut out. The aircraft featured an elliptical intake in the nose.

The design was much more technologically aggressive than that of other early supersonic fighters, such as the US North American F-100 Super Sabre or the Soviet Mikoyan MiG-19. Petter, one of Britain's most prominent aircraft designers, may have been influenced by German concepts generated late during the war.

Although the MoS was enthusiastic about the P.1, the Royal Aircraft Establishment (RAE), Britain's experimental aircraft organization, found fault with it. The RAE awarded a contract to Short Brothers to build a piloted demonstrator aircraft, the Shorts "SB.5", to prove their points. Although the SB.5 was along the lines of a subscale P.1, officially it had nothing to do with the EE project.

The SB.5 performed its initial flight on 2 December 1952, with Tom Brooke-Smith at the controls. It featured a Rolls-Royce Derwent centrifugal-flow turbojet engine, with a maximum thrust of 75.7 kN (7,720 kgp / 3,500 lbf), and fixed tricycle landing gear. The wings were designed to allow the sweep to be modified by ground crew. The demonstrator also evaluated different tail configurations, including a "tee" style tail arrangement, with a triangular tailplane mounted on top of the tailfin, and a tail arrangement with the tailplanes mounted low on the rear of the fuselage.

The RAE wanted to demonstrate the superiority of the tee arrangement over the more conventional low-mounted horizontal tailplanes of the P.1. As it turned out, when the low-mounted tailplane was first flown on the SB.5 in 1954 it was demonstrably the better idea, but the P.1 was almost ready to fly by that time and the EE design team had apparently never taken the tee tail concept seriously. The only result was that the SB.5 confirmed what Petter and his design team had believed all along anyway. The SB.5 ended up in the Royal Air Force (RAF) Museum at Cosford.

The first P.1 performed its initial flight from Boscombe Down on 4 August 1954, with the famed test pilot Roland "Bea" Beamont at the controls. Beamont had flown the SB.5 beforehand to familiarize himself with the peculiarities of the configuration. The second flying P.1 prototype performed its initial flight on 18 July 1955. Both prototypes were powered by two Armstrong Siddeley Sapphire Sa.5 nonafterburning axial flow turbojet engines. Even with the nonafterburning engines, the prototypes were able to easily exceed the Mach 1.2 specification.

Although the P.1 was officially a research aircraft, it had been designed to be close to an operational fighter configuration. Performance was so outstanding that the decision was quickly made to proceed on an operational version that would be capable of Mach 2. In fact, the second P.1 prototype featured items such as a bulged belly tank and fit of twin Aden Mark 4 30 millimeter revolver-type cannon, bringing it closer to operational specification.

Orders were placed for three "P.1B" prototypes for a production interceptor. The P.1 was retroactively designated the "P.1A". The P.1B was to feature twin Rolls-Royce Avon afterburning engines; a larger tailfin; airborne intercept (AI) radar in a cone in the inlet, which was changed from elliptical to circular; a spine containing fuel for an engine starter system; a raised cockpit; and armament of twin Aden cannon in the upper nose, plus a pack under the cockpit that could either support two De Havilland Blue Jay (later Firestreak) heat-seeking air to air missiles (AAMs) or 44 Microcell 5 centimeter (2 inch) unguided rockets. The unguided rocket pack was in two sections that hinged outward to deploy along each side of the fuselage.

Since the test programs of the earlier British Supermarine Swift and Hawker Hunter jet fighters had been delayed because too few prototypes had been built, the initial order for three P.1Bs was followed by an order in February 1954 for a "development batch" of 20 more machines for test and evaluation.

The initial P.1B prototype performed its first flight on 4 April 1957, again with Beamont at the controls. He and Jimmy Dell were the primary test pilots for the development program. This initial machine did not have a ventral tank, though it appears both the other two P.1Bs in the first batch did. The first P.1B was later refitted with the ventral tank, and was also used to test a forward tailfin extension that was not adopted for production. On 25 November 1958, a P.1B fitted with early afterburning Avons exceeded Mach 2.

The development program was leisurely, not marked by any sense of urgency, partly because the aircraft was seen as so advanced that there was no real need to rush it into service.

Ironically, at the same time the P.1B was making its initial flight, British Defense Minster Duncan Sandys (pronounced "Sands") released his infamous "White Paper" that stated that the day of manned combat aircraft was over and that guided missiles were the way of the future. Sandys has been bitterly attacked by British aviation enthusiasts ever since.

Somewhat in his defense, Sandys was not completely alone in his views, since the same point of view was also in fashion to an extent in both the US and the Soviet Union. Missiles were seen as the way of the future, and it wasn't appreciated for another decade that the whizzy missiles being developed in the 1950s wouldn't turn out to be so whizzy when they actually went into combat.

The Suez crisis of 1956 also had a major impact: after Egypt seized the Suez canal in that year, the British collaborated with the French and Israelis to take it back, only to be bluntly told to get out by the Americans and the Soviets. Although the British Empire had been disintegrating rapidly since the end of World War II, the Suez fiasco was the obvious last hurrah, and with the end of imperial glory there was a clear need to downsize Britain's aviation industry. Unfortunately, instead of a "soft landing", the downsizing ended up being more like a disastrous wreck that left debris strewn over the landscape.

The main effect of the White Paper was to cause the cancellation of a number of promising British aircraft projects. Work on the P.1B was too advanced to cancel, and in fact the White Paper had the somewhat contrary effect of confirming the program as an interim solution until the missile wonder weapons were available. That was the good news. The bad news was that implementation of several useful refinements to the type would be delayed for a long time, and in fact several basically simple and useful upgrades would never be implemented at all. The conventional wisdom was that the type would be out of service by 1964, so there was no reason to spend time and money on frills.

The first of the development batch machines made its initial flight on 3 April 1958, with the rest following over the next year and a half. In October 1958, Sir Dermont Boyle, chief of air staff, gave the type the designation of "Lightning", in preference to the stuffier name of "Excalibur". Fifty full production machines had already been ordered in November 1956, and the first full production "Lightning Fighter Mark 1 (F.1)" made its initial flight on 3 November 1959.

The RAF received its first Lightnings in December 1959, in the form of three development batch P.1Bs to be used for operational workup. Incidentally, some or all of the P.1Bs were apparently retroactively redesignated "Lightning F.1s" at some time, but if so this is a minor semantic issue. The actual configuration of the development batch machines not only seems to have varied from machine to machine, but in the configuration of individual machines over time. The development batch aircraft are all referred to as "P.1Bs" in this document.

RAF Number 74 Squadron at Coltishall was the first full service unit, with the pilots acquiring familiarization with the type during late 1960 and the squadron declared operational in 1961. Number 74 Squadron, the "Tigers", had a distinguished service history from both World Wars. The P.1As and P.1Bs went on to have productive careers as test and evaluation aircraft. At least one of the P.1As survives, on display at the RAF Museum at Cosford, in the company of the Short SB.5 and a P.1B.

English Electric (BAC) Lightning F.1 Described / F.1A

The Lightning was one of the most distinctive combat aircraft to ever reach full operational service. It had a very vague resemblance to some Soviet fighter designs, but its "cutout delta" wing and over-under engine arrangement made it clearly different from any other major first-line combat jet fighter ever built. Some found it sleek and futuristic, others angular and strange, but all agreed that it was an unusual machine.

The Lightning was of all-metal construction, mostly aircraft aluminum with some steel and small amounts of titanium. The wings featured ailerons on the ends and flaps inside the cutouts, as had been demonstrated on the P.1A. The P.1A had leading-edge flaps, but these were not fitted to production Lightnings; in addition, the P.1A's flaps had been split, while production aircraft had one-piece flaps with fuel storage. Most of the fuel storage was in the wings, backed up by fuel in the ventral tank. The ventral tank could be jettisoned in flight. Each wing featured a small sawcut about three-quarters of the way down its leading edge, intended to provide improved aileron response and prevent separation of airflow from the wingtips.

The tailfin was fixed and had a rudder, while the tailplanes were all-moving slabs. There was a single dorsal fin under the ventral tank to improve yaw stability. There were also twin hydraulically-operated airbrakes, one on each side of the upper fuselage forward of the tailfin.

All the landing gear assemblies had single wheels. The nose gear retracted forward; in the P.1A it had pivoted 90 degrees during retraction, but this was not done on production machines. The main gear, which had a small forward slant when extended, retracted outward from a hinge point in the wings, the tires pivoting 60 degrees during retraction. The main gear wheels were narrow in order to fit into the wing, and burst tires were a common problem. The main tires had to be replaced after no more than seven landings.

The nosewheel was not steerable, with the pilot turning the machine on the ground using differential braking. The nosewheel could caster 30 degrees to each side, with an alignment system ensured the nosewheel was pointed straight ahead on landings. A nosewheel steering system had been developed, but would never be adopted on any production Lightning.

The F.1 was fitted with two Avon 201 (RA.24R) engines, featuring an afterburner with four thrust settings, providing 50.06 kN (5,103 kgp / 11,250 lbf) max dry thrust and 64.2 kN (6,545 kgp / 14,430 lbf) afterburning thrust each. Some F.1s, possibly only development batch P.1Bs, apparently at least initially had the earlier Avon 200R engine, with the same thrust but a simple on-off afterburner.

The engines were arranged top and bottom and staggered, with the inlet of the bottom engine towards the front of the wingroot and the inlet of the top engine towards the rear of the wingroot, to ensure an absolutely minimal cross section. The powerplant arrangement not only reduced drag but made engine-out handling relatively straightforward. However, it also meant that the two engines had to have exhaust pipes pipes of different lengths, and the close proximity of the engines tended to ensure that the catastrophic failure of one would knock out the other. Access to the engines was good, through large hatches on the top and bottom of the fuselage. The top engine was lifted out through the top hatch after the exhaust pipe was pulled out the tail, while the bottom engine was dropped out the bottom hatch.

The engines were started by a Plessey isopropyl nitrate (AVPIN) system. Isopropyl nitrate is a nasty, toxic, corrosive substance that can burn without oxygen. Fumes drifting into the cockpit could be a hazard, and spills would strip paint off the fuselage. A total of 13.6 liters (3.6 US gallons / 3 Imperial gallons) of isopropyl nitrate was stored in the fuselage spine, enough for six starts. The AVPIN system was troublesome but regarded as better than reliance on ground-starter systems, which might be hard to come by when Lightnings operated from remote airfields. In another decade, the gas turbine auxiliary power unit (APU) would provide a much better solution to the problem.

The pilot sat under a clamshell canopy that hinged to the rear. Cockpit field of view was good by the standards of the time, and the cockpit was pressurized and climate-conditioned. The pilot sat on a Martin Baker Mark BS4.C Mark 2 ejection seat, capable of operating down to zero altitude but with a minimum speed of 167 KPH (104 MPH / 90 KT).

The Lightning's Ferranti AI.23 AIRPASS radar and fire-control system allowed it to perform tail-chase intercepts day or night, and in foul weather. The radar was in the intake bullet, which was mounted on two struts, top and bottom, inside the inlet, with the lower strut accommodating a gun camera. Other Lightning avionics included a TACAN beacon-navigation system as the primary navigation aid, backed up with an instrument landing system (ILS). A VHF radio was fitted initially, as well as an identification friend or foe (IFF) system. Not too unusually for the time, the Lightning had no defensive countermeasures systems; it never would have any.

Armament consisted of twin Aden Mark 4 30 millimeter revolver-type cannon, firing from the top of the nose and with 130 rounds per gun, and two de Havilland Firestreak heat-seeking AAMs mounted on stub pylons on the lower fuselage below the cockpit. The Firestreaks could be swapped out for the pack of 44 unguided rockets or another pair of Aden cannon. However, as noted the idea that guided missiles were the way of the future was in fashion at the time, and the Firestreaks were the usual weapon. The Aden cannon in the top of the nose were actually not often fired since they blinded the pilot. In fact, the gun ports were usually faired over in the field to reduce drag, except for Lightnings serving with RAF Germany, where the type was assigned a secondary ground-attack role.

Incidentally, English Electric performed work on integrating the Hughes Genie AAM, a large weapon that made up for its lack of guidance by using a nuclear warhead, with a Lightning carrying one such missile semi-recessed under the forward fuselage. Nothing came of this exercise.

Pilots were excited by the Lightning. It was a far more powerful machine than the Hawker Hunter: it was very fast, with a snappy rate of roll due to its short span and well-thought-out aileron scheme, and a terrific zoom climb in full afterburner. A Lightning had no great trouble performing a dash to 18.3 kilometers (60,000 feet), and one may have unofficially reached 23.8 kilometers (78,000 feet), at which point it was no doubt flying about as well as a brick and with flamed-out engines. Lightnings actually intercepted high-flying US Air Force Lockheed U-2 spy aircraft operating out of Wethersfield, irritating USAF brass, and late in its career a Lightning would even outclimb a McDonnell Douglas F-15 Eagle. To be sure, the Lightning was flying clean and the F-15 was not -- presumably at least carrying wing drop tanks -- but even factoring in handicapping it was still an impressive achievement.

The Lightning was awe-inspiring in public flight displays because of its snap, power, and sheer thunderous noise, and several RAF Lightning display teams would be formed during its time in service. The best-known was the "Firebirds" team of Number 56 Squadron, which flew red-trimmed Lightnings for a year or so in the early 1960s. Lightnings performed the flypast for Winston Churchill's funeral in 1965, and in the next year, 1966, twelve Lightnings put on a hell of performance at the Paris Air Show.

There was the issue that such a powerful aircraft was something of a handful, with such unpleasant features as a high stall speed and a fast landing speed. It featured a drag chute to reduce the landing roll. Apparently the Lightning was sometimes known as the "Frightening", and it is a fact that only experienced pilots were assigned to fly the type, and then only after thorough qualification. That in itself enhanced the elite status of a posting to a Lightning squadron. Once mastered, however, the Lightning was a very rewarding ride. The accident rate was surprisingly low. The lion's share of the accidents were due to engine fires -- a nagging weakness of the Lightning -- not landing or other handling accidents.

The F.1 had significant weaknesses. One of the worst was an inadequate fuel supply and minimal endurance, a problem that would plague the Lightning through its entire life in spite of all attempts to fix it. For a time, Number 74 Squadron's F.1s were forced to fly without the ventral fuel pack while a bug was worked out, reducing them to (as was once said of another aircraft) "fighters for defense over the airfield beacon".

Another problem was that the Lightning's relative sophistication, in comparison with the austere Hunter, led to serious maintenance headaches. It was also not all that well designed for serviceability, and at first the aircraft's availability rate was very poor. Incidentally, endurance and maintainability were also often problems with contemporary sophisticated Mach 2 interceptors of other nations. Interestingly, the AIRPASS radar apparently was fairly reliable and worked well, it seems because it was a solid but not "bleeding edge" design.

Only 19 F.1s were built, not counting a single static-test aircraft, before production moved on to the "F.1A", a minor revision that added a UHF radio, with longer range and a radio-compass capability, and featured:

• An external wiring conduit running along the lower fuselage on each side, instead of wiring runs inside the engine bay as featured on the F.1.
• An improved windscreen rain-dispersal arrangement.
• A detachable flight refueling probe under the left wing, near the wingroot. The probe tip was just forward of the cockpit, allowing the pilot to keep an eye on the refueling hose basket, and a light was fitted at the base of the probe to provide illumination at night and in foul weather.

Initial service deliveries of the F.1A were in early 1961. By this time, the Lightning had become the "British Aircraft Corporation (BAC)" Lightning, since English Electric had been absorbed into the BAC organization on 12 January 1960.

Author: Greg Goebel

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