The Supermarine Spitfire was designed by Reginald J. Mitchell / Reginald Mitchell / R. J. Mitchell. The Spitfire was based on the seaplanes that won the Schneider Trophys.
The design was to meet Air Ministry Specification F.7/30.
The cockpit on the Spitfire had a teardrop hood allowing for good views in the early models. Later models had bubble canopies.
The pilot was protected by a sheet of armor.
The designers of the Spitfire claimed that the ejector exhaust stubs increased it's speed by 3 mph / 5 kph.
One of the Spitfire's strengths was it's wing as it had low drag and excellent strength.
Spitfires that were designed for low level attacks had clipped wings to allow for better agility.
The undercarriage was narrow and retracted outwards. This did not provide a stable platform when landing.
In the prototype there was a tail skid, but in the production version a tail wheel replaced it.
Spitfire Mk I
Early models of the Spitfire Mk I had the Merlin II engine, whereas later models had Merlin III engines. The early models also had a 2 blade propeller, which was later replaced by a 3 blade propeller.
The two bladed fixed pitch propeller was replaced by a three bladed variable pitch propeller during 1938-1940.
Spitfire Mk V
The Spitfire Mk V was a design combining the Mk I and Mk II airframe with the Rolls-Royce Merlin 45 engine.
Improvements During Production
The ailerons changed from being fabric covered to metal covered. The Merlin 50 and Merlin 55 engine had negative 'g' carburetors to help eliminate stalls in tight turns and maneuvers. The armor was also increased.
Drop tanks were developed for the Spitfire Mk V.
A tropical version of the Spitfire Mk V had a large Vokes filter under the nose.
Spitfire Mk VI
The Spitfire Mk VI was designed to intercept high flying German aircraft operating over Britain in 1941.
The Mk VI was based on the Spitfire Mk VB's airframe and wing.
The Spitfire Mk VI was the first to have a four blade propeller.
The wingtips were extended to help with better control at high altitudes.
The cockpit was lightly pressurized (2 psi). This was located between the bulkheads for and aft of the pilot's cabin. The sealed cockpit canopy could not be slid open as it was bolted down and sealed before takeoff.
Internal fuel capacity was increased by 33% with the addition of a fuel tank in the rear fuselage.
Spitfire Mk VII
The Spitfire Mk VII was the first substantial redesign of the Spitfire series. Its structure was strengthened.
The Spitfire Mk VII used a Rolls-Royce Merlin 60 series engine. There were 6 port exhausts. The radiators were symmetrical underwing.
The 'C' wing had shorter span ailerons and additional fuel tanks in the leading edges. The span was longer to help with high altitude work.
The tail wheel was retractable. Many had the pointed fin and rudder.
The cabin was pressurized to work at high altitudes.
Spitfire Mk VIII
The Spitfire Mk VIII was nearly the same as the Mk VII but without the pressurized cabin as its primary function was to be used at lower altitudes.
During production the Spitfire Mk VIIIs were tropicallized by having a larger carburetor intake under the nose.
Spitfire Mk IX
The Spitfire Mk IX was designed to battle against the Focke-Wulf Fw 190 that appeared in 1941 as the Mk V was outclassed.
Rolls-Royce developed two more powerful engines, the 60 and 70, that were fitted to a modified Mk V.
Spitfire Mk XII
There was a need for a fighter that could combat the hit and run raids of the Focke-Wulf Fw 190 that were hitting England's south coast. This lead to the installation of the Rolls-Royce Griffon engine.
Early models were based on the Spitfire Mk V airframe with a fixed tail wheel. Later models were based on the Mk VIII with a retractable tail wheel.
The fitting of the Rolls-Royce Griffon engine required that the engine cowling design be changed.
The wings were the clipped 'Cs'.
The tail rudder was pointed.
Spitfire Mk XIV
The Spitfire next had the Rolls-Royce Griffon 65 engine installed. Along with this engine a 5 bladed propeller was used. As a result the nose was longer and the rudder and fin had to be redesigned to compensate for the engine.