PART 1 The Merlin Spitfires


The Spitfire Prototype.....

R.J. Mitchell was responsible for the design of the Supermarine Schneider Trophy racing seaplanes of the early 30s and as will be seen later much of the experience and technology gained by Supermarine and Rolls-Royce during these projects was utilized in the design of what was to become the Spitfire.

The name Spitfire had been used much earlier as the unofficial name for F.7/30 a gull-winged steam cooled fighter designed by Mitchell. Unfortunately this machine never lived up to expectations and didn&undefined;t get beyond the prototype stage. The name was proposed by Sir Robert McLean and agreed by the Air Staff. Mitchell was never happy about the name of what he considered a failed project being applied to his beautiful new creation. When told, that, henceforth K5054 would be known as a Spitfire he barked &undefined;sort of bl**dy silly name they would give it&undefined;

The speed performance of K5054 was initially disappointing, only in the region of 335 mph. Mitchell was greatly concerned, the bush telegraph indicating that this was only marginally faster than the Hurricane. Mitchell was very aware that the Air Staff were hoping for a substantial speed advantage over the Hurricane to justify a production order.


The prototype Hurricane K5083 had made its first flight in the hands of George Bulman, 4 months earlier.
Both aeroplanes had equal power, the Hurricane had a very thick wing, fabric covered humpbacked fuselage using old technology. It was derived from a Hawker Fury bi-plane.


The Spitfire design, however, was unquestionably modern technology, all metal, sleekly streamlined incorporating a very thin wing.
The two bladed wooden propeller was redesigned. Test flights were flown and after correction, the maximum speed had risen to 348 mph, Mitchells objective had always been 350, but 348 was near enough..........
During dive tests the aeroplane is taken to its design maximum permissible indicated airspeed 380 mph IAS (indicated air speed) these tests were conducted at a height, at which, the corrected true airspeed worked at 465 mph. A common occurrence during these high speed dives was for pieces of sheeting and fairing to be ripped off. Another point noted at these high airspeeds was the heaviness of the aileron controls, of great significance later on in the development of this machine.


On 26th May 1936 K5054 was handed over to Squadron Leader Anderson, CO of A Flight A & AEE (Aeroplane & Armament Experimental Establishment) at Martlesham Heath. The trials established a top speed of 349 mph with a service ceiling of 34,500 ft and a take off run of 235 yds in a 5 knot wind.
The question that the Air Ministry wanted urgently answered was the aeroplane capable of being flown safely by ordinary squadron pilots? Fortunately the answer was yes.



Technical description