Supermarine Spitfire. At Royal Air Force's service. Part four. Battle of Britain

 

The Battle of Britain constituted the first major test for the Supermarine Spitfire, whose performance was often compared to that of the Hawker Hurricane, the main fighter of Royal Air Force's (RAF) Fighter Command. 
The Hurricane had thicker wings and its eight 0,303 in machine guns were easier to install and set-up than the Spitfire thanks to having a thicker wing and being closer the one from the other. Some veteran pilots from the Battle of France requested the machine guns to be harmonised, so their combined fire bursts could concentrate in 250 yards (228.6 m) ahead instead of the official 400 yards (365.76 m). This made the Hurricane a better gun platform than the Spitfire.
The Hurricane shot down more enemy aircraft than the Spitfire, thanks to its higher proportion in the skies. In fact, during the Battle of Britain, seven out of ten German aircraft were shot down by Hurricane pilots. However, losses were also higher among the many Hurricane squadrons. According to post-war studies, the kill-ratio of the Spitfire was, however, slightly better than that of the Hurricane.
Most of the Spitfires were armed with a total of eight 0,303 in machine guns, four per wing. It was very common for Luftwaffe's pilots to return home with 0,303 in bullet holes in their fuselages, without having sustained critical damage as their main fighter, the Messerschmitt Bf.109, had received armour plating in critical areas and self-sealing fuel tanks became common in their bombers. 
Those improvements made to German aircraft, required some improvement in armament, so many Spitfires Mk. I of No. 19 Squadron (the first unit to employ them) were fitted with two 20mm Hispano-Suiza cannons. This arrangement, however, proved to be unreliable, as the cannons often failed to fire, or they got jammed very easily. After complaints, those cannons were replaced with conventional machine guns in September 1940. This arrangement was, however, the forerunner of the Mk. Ib variant, which would become standard shortly later and would name, retrospectively, the not-cannon-armed Mk. I variant as the "Mk. Ia". 

The Merlin III engine was rated, theoretically, at 1.030 hp, however it required 100 octane fuel from the United States, which became available only from early 1940. This meant that the emergency boost could last only for five minutes, The extra boost wasn't dangerous as long as the pilot's notes were acknowledged. Anyway, as a precaution, if the boost had been used, the pilot had to report it upon landing, so it could be noted in the engine's log book. This extra boost became standard and more optimized on subsequent variants of the Spitfire. 
Between 1st August and 31st October 1940 a total of 208 Spitfires were lost in combat, seven of them destroyed on the ground and 42 in accidents.

The Speed Spitfire, as we have seen in a previous post, was a speed record variant which was pushed into RAF's service and fitted with photographic cameras, thanks to its high speed. It was one of the fastest aircraft in the world, however it suffered from reduced fuel capacity, so it was, eventually, used as a high-speed hack for the personal use of Air Commodore Boothman. 
It was eventually struck off charge on 14th June 1946 and scrapped. 

Sources:
1st https://en.wikipedia.org/wiki/Supermarine_Spitfire_operational_history#Battle_of_Britain
2nd https://en.wikipedia.org/wiki/Aircraft_of_the_Battle_of_Britain
3rd https://en.wikipedia.org/wiki/Supermarine_Speed_Spitfire

Supermarine Spitfire. At Royal Air Force's service. Part two. Prototypes and early Spitfires.

 

After the disappointment of the Type 224, Mitchell and his design staff, began to draw cleaner designs using the experience with the Schneider Trophy seaplanes as a departing point. This, eventually led to the Type 300, which featured retractable undercarriage and a reduced wingspan. This original design was submitted to the Air Ministry but it was rejected, so it had to undergo a series of changes such as an enclosed cockpit, oxygen-breathing gear, smaller and slimer wings, and it was to be powered by the, back then, cutting edge Rolls-Royce PV XII V-12 engine, which was later commonly known as the Rolls-Royce Merlin. 
In November 1934, Mitchell was given permission from Vickers-Armstrong (Supermarine's parent company) to develop and reife the Type 300 and on 1st December he was given £ 10,000 from the Air Ministry for the construction of the Type 300, under contract AM 361140/34. 
On 5th March 1936 the first prototype, registered as K5054, took-off for the first time at Eastleigh Aerodrome, Hampshire. At the controls was Cpt. Joseph "Mutt" Summers, chief test pilot for Vickers, who praised the design. 
The initial prototype was later fitted with a new propeller and it was flown again on 10th March 1936, where the undercarriage was retracted for the first time and, after a fourth flight, a new engine was fitted. After overcoming many small failures and improving the design, it was flown again to RAF Martlesham Heath where it was handed to Squadron Leader Anderson of the Aeroplane & Armament Experimental Establishment (A&AEE) to be delivered to the Royal Air Force (RAF). Soon after the Air Ministry placed a production order for 310 Spitfires.
Although it was presented to the public on 27th June 1936, numerous problems hindered the mass production of the Spitfire and the first production aircraft wasn't completed until mid-1938 and it was delivered to No. 19 Squadron at RAF Duxford on 4th August 1938 and during the next weeks No. 66 Squadron also received the type, albeit at a slower pace. The next unit to receive the Spitfire was No. 41 Squadron at RAF Catterick and the first public sight of the Spitfire in RAF's colours and markings took place on Empire Air Day, on 20th May 1939. Later, more squadrons were gradually equipped with the type.
When World War 2 began, there were a total of 306 Spitfires in service with the RAF, seventy-one of them in reserve and 2.000 under manufacture with 36 written off due to accidents.
On 6th September 1939, shortly after the outbreak of the war, a friendly-fire incident known as the Battle of Barking Creek took place where two Hawker Hurricanes of 56 Squadron were shot down by Spitfires of 74 Squadron over the river Medway, Kent. One of the victims of this incident, P/O Montague Leslie Hulton-Harrop, was the first British pilot fatality of the World War II. This incident placed the manufacture of IFF (Identification Friend or Foe) equipment as a top priority.
On 16th October 1939 the Spitfire clashed against the German Luftwaffe for the first time when three aircraft from 602 and 603 Squadrons intercepted three Junkers Ju.88 belonging to 1./KG.30 over Rosyth (Fife, Scotland) trying to attack the cruiser HMS Southampton and HMS Edinburgh on the Firth of Forth. Two of the Ju.88 were shot down and another one was heavily damaged.

The PR (Photo-Reconnaissance) variants of the Spitfire, was a sub-variant dedicated for photo-reconnaissance missions. Before the war, military aerial doctrine dictated that the best option for long-range reconnaissance duties was to employ converted bombers, as they had defensive armament, however, it was soon discovered that Bristol Blenheims and Westland Lysanders were easy targets for German fighters so, following a memorandum made back in August 1939 by Flying Officer Maurice Longbottom, two Spitfires, N3069 and N3071 were released from RAF Fighter Command and sent to the Heston flight, a secret reconnaissance unit. 
Those two Spitfires were stripped from their armament and radio gear, two F24 ventral cameras were installed, heating equipment was added to prevent photographic cameras from freezing and the lenses from frosting. These Spitfires were later known as Spitfire Mk. I PR Type A and achieved a high speed of 390 mph (627 km/h) and were employed for the first in late 1939 to perform photographic reconnaissance flights over western Germany.

The Speed Spitfire was an racer-built variant which was built in late 1938 to achieve world speed records, mainly against German aircraft such as the Messerschmitt Bf.109 V13, Heinkel He.100 V2 and the Messerschmitt M.209 V1, which eventually got the prize achieving a top speed of 755.14 km/h (469.22 mph) on 26th April 1939.
It featured many design changes to make the type more aerodynamic and lacked radio equipment and armament to make it lighter. The Speed Spitfire was eventually handed to the RAF at the beginning of World War 2 where it was suited for photographic reconnaissance, given its high top speed. 

Sources:
1st https://en.wikipedia.org/wiki/Supermarine_Spitfire
2nd https://en.wikipedia.org/wiki/Supermarine_Spitfire_operational_history
3rd https://en.wikipedia.org/wiki/Supermarine_Speed_Spitfire
4th https://en.wikipedia.org/wiki/Supermarine_Spitfire_variants:_specifications,_performance_and_armament
5th https://en.wikipedia.org/wiki/Supermarine_Spitfire_(early_Merlin-powered_variants)