English Electric Lightning

At supersonic speed, the Lightning’s shock cone would be heated, weakening the resin in the fiberglass, and exposing the material to fatigue with the thermal cycles of repetitive high-speed flights. At 36,000 ft and Mach 1.7, the heating conditions on the shock cone would be almost identical to those at Sea Level and 650 KIAS,[nb 4] but if the speed were increased to Mach 2.0 at 36,000 ft, the shock cone would be exposed to temperatures more than 70% higher[nb 5] than those at Mach 1.7.

This increase dictated a strengthening of the shock cone to support regular use at speeds up to Mach 2.0 in the Lightning F.2A, F.3, F.6, and F.53.

If the shock cone failed in flight, it could result in pressurization loss[nb 6] or, worse, foreign object ingestion and engine damage.

With the bases for the Lightning’s service limits considered, it is apparent that these limits reasonably accurately reflect the performance of the aircraft itself.

The small-fin variants could certainly exceed Mach 1.7,[nb 7] but the stability limits and shock cone thermal/strength limits would make such operation risky.

The large-fin variants, especially those equipped with Avon 300-series engines could safely reach Mach 2, and given the right atmospheric conditions, might even achieve a few more tenths of a Mach.

It is noteworthy, however, that the same cold conditions that might provide the excess thrust to achieve higher Mach numbers would also decrease the true airspeed at which the airframe and inlet could become unstable.

All variants of Lightning had the excess thrust to slightly exceed 700 KIAS under certain conditions,and the service limit of 650 KIAS was occasionally ignored, even when not driven by operational necessity.

With the strengthened shock cone, the large-tail Lightning variants could safely approach their thrust limit, but fuel burn at high indicated airspeeds was prodigious, and the Lightning might very well run short before eking-out the last few knots.[nb 8] In all variants of the Lightning, the airspeed indicator scale stopped at 700 KIAS.

Climb

The Lightning possessed a remarkable climb rate, and its time to reach an altitude, or time-to-climb, was exceptional.

To achieve this short time-to-climb, Lightnings employed a particular climb profile, which was more shallow in angle compared to that demonstrated at air shows.

The Lightning was famous for its ability to rapidly rotate at the end of the runway and climb almost vertically away, but although this near-vertical climb was impressive, it did not yield the best time to altitude, nor was it a demonstration of the ability to sustain a vertical climb. When Lightning pilots performed their trademark tail-stand, they were actually trading airspeed for altitude.

The Lightnings would seemingly zoom “out of sight,” accelerating away, when in fact they would slow to near stall before pushing over into level flight.

During the optimum time-to-climb profile, the maximum climb angle never exceeded 30 deg.

The Lightning’s optimum climb profile began with an afterburner takeoff. Immediately after takeoff, the landing gear would be retracted and the nose held down to allow rapid acceleration to 430 KIAS, then a climb initiated and stabilized at 450 KIAS.

At this IAS, the climb rate would be constant at approximately 20,000 ft/min.,[5][nb 9]

The Lightning would reach Mach 0.87 at 13,000 ft.[nb 10] The pilot would then maintain Mach 0.87 until the tropopause, 36,000 ft. on a standard day.

The climb rate would decrease during the constant-Mach portion of the profile.[nb 11] If further climb were required, the Lightning would accelerate to supersonic speed at the tropopause prior to resuming the climb at supersonic speed.

A Lighting flying its optimum climb profile would reach 36,000 ft less than 3 minutes after brake release. This was—and is—impressive performance.

That the Lightning never reached the climb rates of some of its contemporaries during this profile was not important; that it reached altitude quickly, was.

The official ceiling was a secret to the general public and low security RAF documents simply stated 60,000+ ft (18 000+ m), although it was well known within the RAF to be capable of much greater heights; the official maximum altitude mainly being determined by cockpit pressurisation reliability and safety.

In September 1962 Fighter Command organized a series of trial supersonic overland interceptions of Lockheed U-2As, temporarily based at RAF Upper Heyford to monitor resumed Soviet nuclear tests, at heights of around 60,000-65,000 ft.

The trials took place in two stages, the second series consisting of 14 interceptions, including four successful and four abortive ones at 65,000.

The late Brian Carroll, a former RAF Lightning pilot and ex-Lightning Chief Examiner, reported taking a Lightning F.53 up to 87,300 feet (26 600 m) over Saudi Arabia at which level "Earth curvature was visible and the sky was quite dark" but control-wise it was "on a knife edge".

In 1984, during a major NATO exercise, Flt Lt Mike Hale intercepted an American U-2 at a height which they had previously considered safe from interception.

Records show that Hale climbed to 88,000 ft (26,800 m) in his Lightning F.3 XR749.

This was not sustained level flight, but in a ballistic climb or a zoom climb, in which the pilot takes the aircraft to top speed and then puts the aircraft into a climb, trading speed for altitude.

The normal service ceiling for this aircraft was 60,000 feet in level flight.

Hale also participated in time-to-height and acceleration trials against F-104 Starfighters from Aalborg. He reports that the Lightnings won all races easily with the exception of the low level supersonic acceleration, which was a "dead heat".

Carroll reports in a side-by-side comparison of the Lightning and the F-15C Eagle (which he also flew) that "acceleration in both was impressive, you have all seen the Lightning leap away once brakes are released, the Eagle was almost as good, and climb speed was rapidly achieved.

Takeoff roll is between 2,000 and 3,000 ft [600 to 900 m], depending upon military or maximum afterburner-powered takeoff. The Lightning was quicker off the ground, reaching 50 ft [15 m] height in a horizontal distance of 1,630 feet [500m]".

In British Airways trials in April 1985, Concorde was offered as a target to NATO fighters including F-15s, F-16s, F-14s, Mirages, F-104s - but only Lightning XR749, flown by Mike Hale and described by him as "a very hot ship, even for a Lightning", managed to overtake Concorde on a stern conversion intercept.

The XR749 now resides at the entrance of Score Group plc's gas turbine testing and servicing facility in Peterhead, Scotland.

Despite its acceleration, altitude and top speed, the Lightning found itself outclassed by newer fighters in terms of radar, avionics, weapons load, range, and air-to-air capability. More of a problem was the obsolete avionics and weapons fit, particularly the 30 mile (very short) range 1950s radar sets: the avionics were never upgraded in RAF service since Lightnings were always supposedly just about to be replaced by something better.