Best of the Battle of Britain
In this corner, the Vickers Supermarine Spitfire; across the ring, the Hawker Hurricane. Which is the more valuable restoration?
- By John Fleischman
- Air & Space magazine, March 2008
(Page 4 of 6)
Unlike idolized Spitfire designer Mitchell, Hurricane designer Sydney Camm did not inspire the making of any wartime biopic. For one thing, Camm was alive and continuing to be his difficult self. "An odd combination of arrogance and diffidence—each characteristic feeding the other" is how one Air Ministry civil servant described him. Yet despite Camm's daily tongue-lashings, the young men who crowded the design office at Hawker worshipped him, according to Fozard, who was one of Camm's apprentices. "Most of us would have walked on glowing coals if he had asked us so to do in the interests of the job," wrote Fozard in his book. Camm, or Sir Sydney, as he became after the war, lived a long, honored life, continuing as chief designer for Hawker-Siddeley until his death in 1966. Camm led Hawker into the Jet Age with the Hawker Hunter fighter and pushed the company into short-takeoff-and-landing technology with the P.1127 project, which evolved into the Harrier jump jet.
Yet Camm is remembered today for the Hurricane, which in turn is remembered as the Battle of Britain fighter that was not the Spitfire.
In truth, the fighters had much in common, starting with the engine they shared, the experimental Rolls-Royce PV-12 that became famous as the Merlin. Both fighters were the product of the frantic rearmament race set off by Hitler's chilling 1934 debut of the Luftwaffe, with its bristling array of swift, low-drag monoplane designs. In 1934, the Royal Air Force's frontline fighter was the Hawker Fury biplane, with a top speed of 200 mph. It had two machine guns, an open cockpit, no oxygen system, and an ineffective radio. The Air Ministry needed a more advanced fighter—quickly. The leading designers were Mitchell at Vickers Supermarine and Camm at Hawker.
Camm came up through the ranks of the Hawker drafting office in the 1920s, working on a series of Royal Air Force biplane designs. Camm's design for the Fury, which he developed in 1931, marked him as a master of Hawker's tradition of building airframes from struts and wire. When the big hurry-up began in 1934, Camm decided against a radical retooling for the new monoplane interceptor. He figured he would have his hands full dealing with the long, liquid-cooled Rolls-Royce engine and his first retractable landing gear.
Before it was bought by Vickers in 1928, Supermarine had been a small niche designer, filling contracts for flying boats. Mitchell also followed the draftsman's route into the aircraft business, rising quickly as an apprentice designer on Supermarine's amphibian projects. In 1925, Mitchell designed the startling Supermarine S.4, a single-seat seaplane racer. To the modern eye, the S.4 looks like a Spitfire on floats. It's not, but if airplanes can be said to have genes, the S.4 is the Spitfire's grandfather. A mid-wing monoplane, the S.4 is driven by a long, narrow, liquid-cooled engine and sits on fully cantilevered floats. There are no bracing wires.
Designing for Supermarine, Mitchell learned how to build in metal. Supermarine's bread-and-butter product in the early 1920s was the two-engine Southampton flying boat. The original, with a hull of double-skin, diagonal mahogany planking, was a fine specimen of traditional boatbuilding but monstrously heavy. Mitchell duplicated the hull but used a light metal alloy that maintained strength, cut weight, and improved performance. Under the skin, his S.4 racer had a conventional strut-and-wire construction, but each succeeding S racer design incorporated more sheet metal. By the time the Air Ministry sounded the alarm in 1934, Mitchell was already working on an all-metal airplane in which the metal skin would serve as the frame: a monocoque design.
By 1934, both teams had started to think about their monoplane designs when Camm and Mitchell received visits from Squadron Leader Ralph Sorley of the Royal Air Force's Operational Requirements Branch. He told them that the Air Ministry had been running tests on a firing range and had determined that it would require 266 hits from .303-caliber ammunition to lethally damage an all-metal bomber. The Air Ministry had further calculated that at a closing speed of 180 mph, a fighter would have two seconds to score. Thus, at 1,000 rounds per minute per machine gun, the new interceptor would need eight .303 Brownings to deliver a total of 266 rounds in a two-second burst. Could the designers squeeze eight guns into their interceptors?
The gun requirement was less of a problem for Camm's prototype Hurricane, which had wings thick enough to house four weapons apiece. But for Mitchell's thinner-wing Spitfire, the eight-gun requirement created a major problem. Beverly Shenstone, a Canadian aerodynamicist, had already convinced Mitchell that the Spitfire should have an elliptical wing, like the one on Germany's high-speed Heinkel He 70 airliner. Then considered the epitome of streamlined design, the He 70 had caused a sensation in British aeronautical circles. Such a planform would permit a speed-friendly, thin thickness-to-chord ratio (the ratio of wing depth to the distance from the leading to trailing edge) while still providing space sufficient to house the guns and retractable landing gear. But now, even this ellipse had to be broadened and skewed slightly forward to ensure that it could retain its thin section yet accommodate the additional weapons. Gone was a Heinkel-like symmetrical ellipse; in its place was the Spitfire's trademark pointy-tip shape.