Spitfire Performance Testing

Spitfire IA
Spitfire IIA
Spitfire V
Spitfire VIII
Spitfire IX
Spitfire XII
Spitfire XIV
Spitfire 21
Seafire IIC
Seafire L IIC
Seafire III
Seafire F Mk. XV
Seafire F.47


News 16 September 2006

WWII Aircraft Performance

8-August-2006 update

Me 109 G Flight Tests

Encounter Reports
of P-51 Mustang Pilots

Nice new Mustang charts:
P-51A-1 Perf. Curves
P-51B High Speed Perf.

28-June-2006 Update
Mustang Performance

New NA P-51B charts,
Mustang III (Merlin 100)
US Report on Tempest V
US Report on FW-190 D-9
P-47C Tactical Trials
P-47N Trial
German Me 109G curves.

Aircraft Comparisons
Spitfire I versus Me 109 E
Spitfire IX versus Me 109 G
Spitfire XIV vrs Me 109 G/K

Aircraft Performance
150 Grade Fuel
Typhoon Performance
Tempest Performance
Mustang Performance
Allison Engined Mustangs
P-47 Performance
P-38 Performance
Fw 190 D-9 Flight Tests
Beaufighter Performance

Other Work
31st Fighter Group
Eagle Squadrons

  The organizations primarily responsible for testing and improving the performance of the Spitfire were as follows:

  • The Ministry of Aircraft Production (MAP). MAP was responsible, on the advise of the Establishments, for the clearance of aircraft and related equipment.
  • The Aeroplane and Armament Experimental Establishment (A&AEE) at Boscombe Down under MAP control. A&AEEs primary role was that of testing aircraft to ensure they were in a fit state for their intended use by the Services. The Establishment was also concerned with aeronautical development and acceptance. Performance testing was carried out fundamentally to establish level speed, climb rate, range, and ceiling. Raw data from flight tests was corrected to standard conditions. Performance reduction methods accounted for position error, compressibility, temperature, and altitude. In addition to the basic performance tests, trials were carried out to assess cooling, handling, and cockpit contamination.
  • The Royal Aircraft Establishment (RAE), Farnborough under the control of the Ministry of Aircraft Production. RAE was engaged in research and theoretical work as well as development of modifications and improvements. Farnborough's wind tunnel was used to test Spitfire aerodynamics and was particulary useful in developing improvements to the Spitfire's ailerons. Fit and finish were assessed and improvements recommended. Also noteworthy was RAE's analysis of captured aircraft.
  • The Air Fighting Development Unit (AFDU) at Wittering and Duxford under the control of Fighter Command and the Air Ministry. The AFDU performed comparitive trials and developed and promulgated tactics effective against the enemy.
  • The Department of Scientific and Industrial Research (DSIR) under the control of the Aeronautical Research Council. Involved in projects to analyse and improve performance.
  • Rolls-Royce's flight test establishment at Hucknall. Flight testing of engines, conversions, and modifications.
  • Vickers-Armstrong (Supermarine) at Worthy Down. Production and development testing.

An Air Ministry document from 29.10.43 details the protocol to use in arriving at performance figures for aircraft:


1.      There are 4 main stages in the evolution of performance for a new aircraft:-

      (1)  Original Estimate - based on drawings and expected engine powers.
      (2)  Flight Tests - Performance of actual aircraft - (a)  Prototype, (b)  Production, when built
      (3)  Provisional Performance Curves - Adjustments of (1) in view of (2)(a).
      (4)  Final Performance Curves - Based on (2)(b) and subject to variation with the condtion of the aircraft.

2.      The limits within which the Stage (1) estimate can be guaranteed depend on whether the new aircraft is -

      (i)   A development of an established type whose characteristics are well known (e.g. Spitfire XIV); or
      (ii)  A new type, about which little or no confirmed information is available, (e.g. F2/43, with Centaurus engine).
      (Note:- The addition of new factors, e.g. Contra-rotating props. to an aircraft in Category (i) would probably transfer it to Category (ii).)

3.      With "Development" aircraft, original estimates should be accurate to within 1-2% in speed, and 50-100 ft./min. in rate of climb. With "New Type" aircraft, however, the error might be up to 6-7% in speed, and 200-250 ft./min. in climb.

4.      Flight Test figures, by themselves, should be treated with considerable reserve, since they may be obtained under non-standard conditions, and the aircraft flown may differ from production machine.

5.      From the prototype trials, Provisional Performance Curves can be obtained, modifying them, if necessary, to allow for the effect of the difference between the prototype and production machine.

6.      Only when trials with representative production machines have been carried out under known conditions can the Final figures be issued. These figures then represent the performance expected of an average production machine of this type.

7.      Any particular machine off the production line, however, may vary from the average in top speed and climb because of differences in engine power and general finish. The usual variation for single-engined fighters is up to 3% in top speed, and 150-200 ft./min. in rate of climb; heavy bombers vary up to 4% in top speed, and 150-200 ft./min. in climb. (...)

Jeffrey Quill, from his perspective as Chief Test Pilot for Supermarine, held the following view of Spitfire testing:

"Every major modification or change, especially those affecting performance or handling qualities, was exhaustively tested by the firm (Supermarine) before submission to the Aircraft and Armament Experimental Establishment at Boscombe Down for official approval. Establishing the accurate performance of any varient involved a lot of flying and a great deal of full power bashing of the engine and systems. As time went on Boscombe Down came increasingly to accept the firm's figures, making only spot checks themselves, in order to save wear and tear on the prototypes. In other words Boscombe Down provided the official seal of approval, though many of the performance figures quoted in their reports were in fact measured by Supermarine's experimental flight test unit at Worthy Down, later at Hight Point. The A and AEE made their own judgements on the aircraft's handling and other qualities. The Air Fighting Development Unit represented Fighter Command, and thus the main users of the Spitfire. They did a most useful job in relating the various British fighters to those of the enemy and in developing tactics on behalf of the command. They were fully entitled to express their opinions about the handling of aircraft and they certainly did so. But the people at Boscombe Down were the final arbiters of what was fit for service use and what was not, and whether or not and aircraft met its specifications and contractual conditions."

[Spitfire Mk IA] [Spitfire Mk IIA] [Spitfire Mk V] [Spitfire Mk VIII] [Spitfire Mk IX] [Spitfire Mk XII] [Spitfire Mk XIV] [Spitfire Mk 21]

[Seafire IIC] [Seafire L IIC] [Seafire Mk III] [Seafire F Mk XV] [Seafire Mk 47]

By Mike Williams and Neil Stirling