The Supermarine Spitfire and Seafire
By Chuck Hawks
The British Spitfire is probably the best known fighter plane ever produced. In a small, informal poll I found that even people with no interest in aviation or history have at least heard of the Spitfire. Often it is the only fighter plane whose name they recognize.
There can be no question that the Spitfire was one of the best and most enduring fighters of World War II. The Spitfire proved, like it arch enemy the Bf 109, to be a very adaptable airplane, and in various versions it served throughout the war.
Most of the famous British aces of WW II flew the Spitfire, including the top scoring British ace of the war Group Captain "Johnny" Johnson (38 victories), and the legless ace and hero of the Battle of Britain, Douglas Bader (he flew with two artificial legs), who scored 9 of his 20 kills from a Spitfire cockpit.
The German ace Gunther Rall (275 victories), who test flew captured versions of practically all of the top Allied fighters, stated that he prefered the Spitfire. This was a common sentiment among German fighter pilots, who commonly regarded the Spitfire as their most dangerous foe.
The Spitfire evolved from the Supermarine line of Schneider Trophy (seaplane) racers of the late 1920's and early 1930's, which culminated in the trophy winning S.6B of 1931. In September of that year, the S.6B captured the Trophy with a top speed of 340.8 m.p.h., and set a world speed record of 407 m.p.h.
The prototype Spitfire was built in 1936. Like the Bf 109, the Spitfire was an all metal stressed-skin monoplane. This was new technology at that time, and many production problems had to be solved, which resulted in considerable delays before the new fighter began reaching RAF squadrons.
The Spitfire was a low drag design that could be progressively improved to keep pace with foreign developments. And, by all accounts, it was a real pilot's airplane. She proved easy to fly and forgiving, a fighter without vices. Her cockpit was relatively roomy and offered a good field of view.
This was in stark contrast to her greatest rival, the ME 109, which was a tricky airplane to control both on the ground and in the air. This was an important consideration during the war, when pilot training was put into high gear and "stick time" reduced. And the 109's cockpit was cramped and had an inferior field of view.
The first production version was the Mk. I, which entered squadron service in mid-1938. When the war came in 1939, the RAF insisted in holding the bulk of their modern monoplane fighters in Britain, sending only a few of the modern Hurricanes, and no Spitfires, to France. This proved to be a good decision as, after the fall of France, RAF fighter command could deploy about 620 Hurricanes and Spitfires to meet the Luftwaffe's 800 Bf 109s. The Luftwaffe also had about 275 Bf 110 twin engine "Destroyer" fighters, but these proved to be no match for the single engine British fighters.
The main variant of the Spitfire Mk. IA was powered by the famous Rolls Royce V-12 Merlin II engine. This produced 1,230 h.p. and drove a two bladed wooden propeller, giving the early Spitfire a top level speed of about 360 m.p.h., and a best climb rate of 2,530 ft/min. By the time of the battle of Britain, a three-bladed constant speed propeller, which markedly improved climb and acceleration, had been fitted.
Typical armament of both Spitfires and Hurricanes of this period was 8-.303 cal Browning machine guns, four in each wing. Some Spitfires were fitted with 2-20mm cannon plus a couple of machine guns, and these were called Mk. IB's.
Either way, their performance was closely similar to that of the Bf 109E, with the Spitfire being easier to maneuver and slightly faster and the Messerschmitt being faster in the dive, and with a quicker roll rate.
In 1940 the Mk. II began to appear, and replaced the Mk. I in early 1941. The Mk. II was powered by a 1,240 h.p. Merlin XII, which gave it a top speed almost identical to the Mk. I (354 m.p.h. at 17,550 ft), but a higher rate of climb (3,025 ft./min).
It is worth mentioning that Spitfires had carburetors, not fuel injection, and the engines would quit for lack of fuel if the aircraft was flown upside down. This problem was not solved until an improved carb was adopted for the late production Mk. V and later models. Mk. II's were also armed with either eight machine guns, or a mix of machine guns and cannons. All Spitfires of this period had the signature elliptical plan wings, and were (in my opinion) among the most graceful of all fighter planes.
History records that these Spitfires (and Hurricanes) prevailed in the Battle of Britain. Their primary shortcoming, again like the Bf 109, was their short range. This was not a problem while they were serving in the interceptor role during the Battle of Britain, but it became a glaring fault when the RAF went over onto the offensive.
Following are the basic specifications for the Spitfire Mk. IIA of September 1940.
The introduction of the Merlin 45 engine (1,185 hp; 1,470 hp war emergency rating at 9,250 feet) resulted in the Spit V. when installed in the basic Mk. I airframe. The Mk. VA configuration was armed with 8-.303 Machine guns and retained the usual rounded wing tips. Only 94 Mk.VA's were produced bfore the Mk. VB went into production early in 1941. The VB for the first time introduced "clipped" wing tips to increase the roll rate. It also featured an improved armament of 2-20mm cannon and 4-.303 machine guns. Some 3,911 Mk. Vb's were produced before the armament was again changed to 4-20mm cannon, thus creating the Mk. VC. A further 2,467 Mk. VC's were produced. By that time Merlin 45, 46, 50, 50A, 55, and 56 engines were being installed in medium altitude versions and Merlin 45M, 50M, and 55M engines were installed in low altitude variants.
The Mk. VC had a top speed of up to 374 mph at 13,000 feet, a service ceiling of 37,000 feet, and a best rate of climb of 2,900 ft./min. But the Spitfire had begun to fall behind the Bf 109F in overall performance. The performance gap increased when the Germans introduced the FW 190A fighter. Never the less, the Mk. V was among the most numerous Spitfire models.
From about January 1940 the Royal Navy had been clamoring for a navalized version of the Spitfire for aircraft carrier use, but the needs of RAF Fighter Command were given priority. Finally, in early 1942, the Royal Navy began receiving the first of 166 Spitfire Mk. VB's modified by the addition of a tail hook and strengthened rear fuselage. These were designated Seafire Mk. IB. In June 1942 the improved Seafire Mk. IIC, based on the Spitfire Mk. VC, appeared. This incorporated catapult spools, a stronger landing gear, and a Merlin 45 or 46 engine. Seafire L Mk. IIC's came with a Merlin 32 engine and a 4-bladed propeller for improved low altitude performance.
In June 1943 the RN began receiving the Seafire Mk. III. This was powered by a Melin 55 engine and, at last, had folding wings. Basic specifications for the Seafire LF Mk. III included a top speed of 348 mph at 6,000 feet, climb to 5,000 feet in 1.9 minutes, service ceiling of 24,000 feet, and range of 513 miles with an external fuel tank.
The MK. VI was designed as a high altitude fighter and featured an increased wing span and a pressurized cockpit. It used the VB airframe. Deliveries started early in 1942 but only 100 were produced.
The next big production model was the Mk. IX, the most numerous of all Spitfire models. The Mk. IX was a Mk. V airframe mated with the new two-stage, two-speed, supercharged Merlin 70 engine, which developed 1,655 hp at 10,000 feet.
This new engine was really intended for the all new Spitfire Mk. VIII airframe, but the press of events forced its adoption in the older airframe. The result, however, was quite satisfactory. Top speed was raised to 415 mph at 27,800 ft. Best climb rate jumped to 4,530 ft./min. The Mk. IX started to enter service around the middle of 1942, and proved able to meet the German fighters on an essentially equal footing. The elliptical wing plan was standard in the Mk. IX, which was approximately contemporary to the Bf 109G. Like that fighter, the Mk. IX served for the rest of the war in a variety of roles.
The Mk VIII finally came along in September 1942, incorporating many detail improvements, including better streamlining and a fully retractable tail wheel. It was usually powered by a 1,710 hp Merlin 64 engine. Top speed was 408 mph at 25,000 ft., service ceiling was 43,000 ft., and best climb rate was 3,790 ft./min. This version was used mostly in the Far East, relatively late in the war. The special high altitude version was the Mk. VII, which like its predecessors featured longer span wings and a pressurized cockpit.
The Merlin engine was reaching its maximum potential by this time and Supermarine was experimenting with adapting the more powerful Rolls Royce Griffon engine to the Spitfire. Seafires with Griffon engines, designed to replace the Mk. III, were also under development.
To deal with the Griffon-engined Seafires first, the initial model was the Mk. XV. This was based on the Seafire Mk. III airframe with an enlarger rudder, powered by a Griffon VI engine developing 1,750 hp. Deliveries began in the fall of 1944. top speed was 383 mph at 13,500 feet, time to 20,000 feet was 7.0 minutes, and service ceiling was 35,500 feet.
The subsequent Seafire Mk. XVII had a teardrop canopy, racks for underwing ordinance, and an improved undercarriage. It used the low altitude version of the Griffon engine, a four-bladed propeller, enlarged rudder, and was armed with 4-20mm cannons.
The Spitfire Mk. XIV of 1944 was a Mk. VIII airframe with a lengthened nose powered by a Rolls Royce Griffon 65 engine. This developed 2,035 hp, good for a top speed at altitude of a sizzling 448 mph. The new engine drove a five bladed propeller and gave the Mk. XIV an improved service ceiling and enhanced high altitude performance. Best climb rate was over 5,000 ft./min. Later Mk. XIV's had a "teardrop" style canopy to improve all-around visibility. Mk. XIV production totaled 957, plus 300 similar Mk. XVIII's.
The last production Spitfires were the Mk. 21, 22, and 24. The Equivalent Navy models were the Seafire F Mk. 45, 46, and 47. The Seafire Mks. 46 and 47 came with a contra-rotating propeller to negate the tendency to swing on takeoff. None of these Spitfire and Seafire models were produced in large numbers. All came with a teardrop canopy, and for the first time the wing was redesigned. The new wing was similar in plan, but was stronger, carried more fuel, housed a longer landing gear (which allowed a larger diameter propeller), and carried four 20mm cannon. The Seafire Mks. 46 and 47 had improved folding wings, while the Mk. 45 had fixed wings. The Seafire 47 served in the Korean War. Top speed of the Spitfire Mk. 22 was 450 mph and best climb rate was 4,900 ft./min.
With these models the Spitfire had reached the end of its long career. The first Mk. 21's entered service in April 1945; the last Mk. 24's were delivered in March 1948. The war was over and the jet age had begun. A total of about 22,800 Spitfires and Seafires of all types had been produced.
Copyright 2003 by Chuck Hawks. All rights reserved.