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