English Electric Lightning - Design - Overview

Overview

There were several unique and distinctive features in the design of the Lightning; principally the use of stacked and staggered engines, a notched delta wing, and a low-mounted tailplane. The vertically stacked, longitudinally staggered engines was the solution devised by Petter to the conflicting requirements of minimizing frontal area, providing undisturbed engine airflow across a wide speed range, and packaging two engines to provide sufficient thrust to meet performance goals. The configuration allowed the twin engines to be fed by a single nose inlet, with the flow split vertically aft of the cockpit, and the nozzles tightly stacked, effectively tucking one engine behind the cockpit. The result was a low frontal area, an efficient inlet, and excellent single-engine handling. Unfortunately, this stacked configuration led to complicated maintenance procedure, and the recurring problem of fluid leakage from the upper engine being a fire hazard.

The fuselage was tightly packed, leaving no room for fuel tankage or main landing gear. While the notched delta wing lacked the volume of a standard delta wing, each wing contained a fairly conventional three-section main fuel tank and leading-edge tank, holding 312 imp gal (1,420 l); the wing flap also contained a 33 imp gal (150 l) fuel tank and an additional 5 imp gal (23 l) was contained in a fuel recuperator, bringing the aircraft's total internal fuel capacity to 700 imp gal (3,200 l). The main landing gear was sandwiched outboard of the main tanks and aft of the leading edge tanks, with the flap fuel tanks behind. The long main gear legs retracted toward the wingtip, necessitating an exceptionally thin main tyre inflated to the high pressure of 330–350 psi (23–24 bar).

A conformal ventral store was added to the design to house, alternatively, a fuel tank or a rocket engine. The rocket engine, a Napier Double Scorpion motor, also contained a reserve of 200 imp gal (910 l) of high-test peroxide (HTP) to drive the rocket’s turbopump and act as an oxidizer. Fuel for the rocket would have been drawn from the Lightning’s internal tankage. The rocket engine was intended to boost the Lightning’s performance against a supersonic, high altitude bomber threat, but this threat never emerged, thus Lightning’s basic performance was deemed sufficient and the rocket engine option was cancelled in 1958. The ventral store saw wide use as an extra fuel tank, initially this was jettisonable and held 250 gal (247 gal usable, 1,120 l). Later ventral tanks were non-jettisonable.

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. The radar had a short range and no track-while scan capability; it could only detect targets in a fairly narrow (40 degree arc). While an automatic collision course attack system was developed and successfully demonstrated by English Electric, it was not adopted owing to cost concerns. Plans to supplement or replace the obsolete Red Top and Firestreak missiles with modern AIM-9L Sidewinder missiles never came to fruition because of lack of funding,