Thanks to its unrivaled performance, the Lightning was used in the late 60s to carry out proving flights to allay fears over the effects of Concorde flying at Mach 2 over land
Originally conceived as an interceptor tasked with protecting the V-Force airfields during the Cold War, the English Electric Lightning was a Mach 2 aircraft whose extraordinary rate of climb earned it the memorable description of a pilot riding atop two rockets.
Its operational ceiling was treated as classified information, though it was widely understood to exceed 60,000 ft. Equally legendary was its climb rate, which topped 20,000 ft per minute — a figure that placed it in a class of its own among contemporary fighters.
This exceptional performance made the Lightning a natural candidate for a series of proving flights in the late 1960s, designed to assess the potential impact of Concorde flying supersonically at Mach 2 over populated areas.
According to an account published on Quora, the tests took place around 1965 at RAF Bourn in Cambridgeshire, where invited guests — including press and officials — were formally received ahead of the flights. The plan called for Lightnings to overfly the area at approximately 20,000 ft and Mach 2, or around 1,350 mph at that altitude. Because the Lightning was considerably less aerodynamically refined than Concorde, the runs were conducted at a lower altitude than the supersonic airliner would have used, in order to generate a comparable sonic boom.
Reporters had been stationed at a number of potentially vulnerable locations in advance — among them commercial greenhouses and agricultural buildings housing livestock.
The aircraft were heard clearly during the timed passes. As one observer noted, the common misconception is that an aircraft “breaks” the sound barrier — in reality, once supersonic compressibility is established, the accompanying shockwave travels with the aircraft for as long as it maintains Mach 1 or above. In the Lightning’s case, this meant Mach 2 — though not for long. At full power, the aircraft burned through fuel so rapidly that twenty minutes of flight represented a substantial sortie.
Reporters waiting by phone began receiving calls. Seventeen panes of glass had shattered at one location. At another, an entire herd of cattle had been so badly startled that it took around twenty minutes to settle them.
When the press conference got underway, the Ministry team appeared satisfied with proceedings — until the journalists confronted them with these precise details: seventeen broken greenhouse panes at one site at 15:01, and a herd of Aberdeen Angus left in disarray at another.
The reporters, by their own account, were rather pleased with themselves — all the more so given the champagne and caviar that had accompanied the occasion.
Concorde, as it turned out, was never permitted to fly supersonically over land. Instead, she would climb subsonically over the Irish Sea before the afterburners were engaged — a routing constraint that contributed significantly to the economic penalties that ultimately rendered the aircraft commercially impractical.
Photo by BAE Systems and Crown Copyright
