Super Supermarine Spitfire :
Although no country has ever been saved by the actions of a single man, there are many in the UK who would argue that, while their survival, as a country, may have been guided by Winston Churchill, he couldn’t have done it without tools designed by Reginald Mitchell. Those tools are known by the name “Spitfire.”
With her factories just barely out of range of German bombers, and the enemy barely two dozen miles from her shores, when it came to fighters, Britain was continually engaged in a game of one-upsmanship. Messerschmitts and FW’s would get a little faster, with more climb and Britain would generate another Spitfire model that would better it.
Finally, however, it became obvious that making the quantum leap necessary to give their fighter pilots a decided edge was going to be difficult: they had used up all of the potential of the original 1,600 cubic inch Merlin engine. So, the Brits did what those in search of performance have always done: add cubic inches. In this case, the new engine, which had actually been designed in the 1920’s, the Griffon, displaced a whopping 2300 cubes!
Lest we think the Brits had gone over to the American approach of solving the problem with a bigger hammer, let’s put the entire Merlin engine and Spitfire line in perspective against the competition. The original Merlin displaced just a little over 1600 cubic inches while the DB601 of the Messerschmitt was 2450 inches and the BMW801 of the FW-190 was 2656 cubic inches. The fact that aircraft like the Mk. IX Spit could successfully fight airplanes with much larger engines to a stand still was miraculous and a tribute to the Rolls-Royce ability to make do with less and the Supermarine engineers’ ability to continually clean up what was already a clean airframe.
In the Mk. XIV (14 to those who are Roman Numeral-challenged) and its Griffon 61 engine, you had the same relatively tiny airframe (by American standards) but shoe-horned under the cowl was a monster. Using two-stage supercharging to maintain power to altitude, the Griffon gave its pilot 1850 horsepower to play with at 21,000 feet, an almost unheard of number. That was more horsepower than the Merlin generated in fat air at sea level! The bigger engine is also why Griffon-powered Spitfires have the long characteristic bulges running down both sides of the top of the cowling. It’s shoulders were too wide to fit any other way.
As an airplane climbs, the thinner air means it has less drag, but it also usually means it has less horsepower. However, with a two-stage supercharger ramming copious amounts of the thin air into the engine, the horsepower is maintained and the airplane becomes much faster. In the case of the Mk. XIV, it was capable of 448 mph at 26,000 feet and its service ceiling was boosted to 44,500 feet, which is pushing the upper limits of propeller driven, non-pressurized aircraft.
The Mk. XIV was produced in a number of different configurations,
including later versions with cut down rear fuselages and a bubble
canopy for better visibility. The wing was also standardized to use
Hispano-Suiza 20mm cannons or good old American .50 Brownings, although
those were seldom seen.
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