Spitfire Mk I Performance Testing

Aeroplane and Armament Experimental Establishment
Martlesham Heath

September 1936

Handling trials of the
Spitfire K.5054

SUMMARY OF FLYING QUALITIES.

               The aeroplane is simple and easy to fly and has no vices. All controls are entirely satisfactory for this type and no modification to them is required, except that the elevator control might be improved by reducing the gear ratio between the control column and elevator. The controls are well harmonised and appear to give an excellent compromise between manoeuvrability and steadiness for shooting. Take-off and landing are straightforward and easy.

               The aeroplane has rather a flat glide, even when the undercarriage and flaps are down and has a considerable float if the approach is made a little too fast. This defect could be remedied by fitting higher drag flaps.

               In general the handling of this aeroplane is such that it can be flown by the average fully trained service fighter pilot, but there can be no doubt that it would be improved by having flaps giving a higher drag.

For more of this report see HERE


Aeroplane and Armament Experimental Establishment
Martlesham Heath

6 January 1939

Spitfire K.9787
Merlin II
Fixed pitch wooden airscrew
Performance Trials

Results of Trials.

                A comparison is made in the table below between this production aeroplane and the prototype K.5054.

 Prototype
K.5054
Production
K.9787
Maximum speed349 at 16800362 at 18,500 ft.
Maximum cruising speed (at 15,000 ft.)    311 m.p.h.    318 m.p.h.
Time to 15,000 ft.   5.7 mins.   6.5 mins.
Time to 30,000 ft.17.0 mins22.4 mins
Service ceiling35,400 ft.31,900 ft.
Weight5332 lb.5819 lb.

Summary of Trials

Height
ft.
T.A.S.
m.p.h.
Time
From
Start
Min.
Rate
of
Climb
Ft./Min.
Sea Level 2090
  2,000295      1.02195
  5,000307      2.32295
10,000328      4.32490
11,000   4.82530
15,000348      6.52065
16,500355      7.21890
18,000361      8.11710
18,500362.5   
20,000360.5  9.41480
25,000349    13.6  900
30,000315    22.4  325
Service ceiling = 31,900 ft.

Flying weight on trials = 5819 lb.

For more of this report see HERE


Aeroplane and Armament Experimental Establishment
Martlesham Heath

15 June 1939

Spitfire K.9787
Merlin II
Fixed pitch wooden airscrew
Fuel Consumption tests, handling and diving trials

Fuel Consumption Tests in Level Flight
Weight Normal Load 5804 lb.

    OPERATIONAL HEIGHT:- 15,000 FT.                              SPECIFIED CRUISING SPEED     -
    WEIGHT BEFORE FLIGHT:- 5804 lb.                                ESTIMATED MEAN WEIGHT:-     -
    TYPE OF FUEL USED:- D.T.D. 230.                                  SPECIFIC GRAVITY OF FUEL AT 60°F:- 0.75
I.C.A.N.
Height
ft.
AIR SPEED
m.p.h.
R.P.M.Boost
Pressure
lb/sq.in.
Mixture ControlConsumption
(S.G. .75)
Statue
Air
Miles
Per Gall.
TrueA.S.I. lb/Hr.Galls/Hr.
 
7000
200184.51770-4.3Auto Weak181   24.1  8.3  
220204.51895-3.0"200   26.658.26
240224   2020-1.6"231   30.8  7.8  
260243.521550  "275.536.757.08
280261.52300+1.9Auto Rich409   54.5  5.14
300280   2440+3.8"466.562.2  4.83
322300   2600+6.0"591   78.8  4.09

                The most economical speed at this height is about 200 m.p.h. A.S.I. and full control of the aeroplane is obtained at this speed.


Fuel Consumption Tests in Level Flight
Weight Normal Load 5804 lb.

    OPERATIONAL HEIGHT:- 15,000 FT.                              SPECIFIED CRUISING SPEED     -
    WEIGHT BEFORE FLIGHT:- 5804 lb.                                ESTIMATED MEAN WEIGHT:-     -
    TYPE OF FUEL USED:- D.T.D. 230.                                  SPECIFIC GRAVITY OF FUEL AT 60°F:- 0.75
I.C.A.N.
Height
ft.
AIR SPEED
m.p.h.
R.P.M.Boost
Pressure
lb/sq.in.
Mixture ControlConsumption
(S.G. .75)
Statue
Air
Miles
Per Gall.
TrueA.S.I. lb/Hr.Galls/Hr.
 
15,000
220179   1975-Auto Weak202   26.9  8.18
240197.52090-3.9"218   29.1  8.26
260214.52220-2.6"242   32.258.06
280232   2345-1.3"277.537.0  7.56
300249   2485+0.3"325.543.4  6.91
317262.52600+1.7"377   50.3  6.3  

                Most economical cruising speed is approximately 200 m.p.h. A.S.I. At this speed the aeroplane is fully controllable.

For more of this report see HERE


Aeroplane and Armament Experimental Establishment
Martlesham Heath

12 July 1939

Spitfire K.9793
Merlin II
Short Performance with 2 pitch metal airscrew

Summary of Results.

 

                   The take-off is much improved over that with the wooden airscrew, and the maximum speed is increased from 362 m.p.h. with wooden airscrew to 367 m.p.h. with the 2 pitch metal airscrew. The climb performance with metal airscrew is also better considering the increase in weight.

Summary of Trials

Height
ft.
T.A.S.
m.p.h.
Time
From
Start
Min.
Rate
of
Climb
Ft./Min.
  2,000     1.291625
  5,000   3.01845
  9,700   5.42175
10,000   5.52150
15,000   8.11725
16,500358.5  8.91600
18,000365      9.91475
18,600367      
20,000366    11.41305
23,000 14.01055
26,000 17.2  800
28,000 20.0  630
30,000 23.8  470
Service ceiling (Estimated) = 34,400 ft.

Flying weight on trials = 5935 lb.

For more of this report see HERE


Aeroplane and Armament Experimental Establishment
Martlesham Heath

20 July 1939

Spitfire L.1007
Merlin III
Handling and performance trials with two 20 m.m. cannon fitted

       The aeroplane is fitted with a 2-pitch 3-blade metal airscrew and it was desired to compare the handling and the performance of the aeroplane with that of Spitfire K-9793, fitted with Browning guns and 2-pitch metal airscrew.

Summary of Trials

Height
ft.
T.A.S.
m.p.h.
Time
From
Start
Min.
Rate
of
Climb
Ft./Min.
  2,000 1.01970
  5,000 2.52040
10,000 4.92170
13,000339    6.41920
15,000348    7.51750
16,500354.58.41620
18,000360.59.31490
18,600364      
20,000362.510.7  1320
23,000359    13.2  1070
26,000354    16.4    820
Service ceiling = 34,500 ft.

Flying weight on trials = 5925 lb.

For more of this report see HERE


Aeroplane and Armament Experimental Establishment
Boscombe Down

19 March 1940

Spitfire N.3171
Merlin III
Rotol Constant Speed Airscrew
Comparitive Performance Trials

              In accordance with Air Ministry letter, reference B.9242/39/A.D./R.D.L. dated 4th November 1939, performance trials have been carried out to compare this aeroplane with the standard Spitfire I fitted with a 2-pitch airscrew.

Summary of Trials

Height
ft.
T.A.S.
m.p.h.
Time
From
Start
Min.
Rate
of
Climb
Ft./Min.
  2,000    .72,820
  5,000 1.82,850
10,000320   3.52,895
11,000 3.92,905
15,000339   5.42,430
18,900354     
20,000353.57.71,840
25,000345   11.0  1,250
30,000319   16.4      660
Service ceiling = 34,700 ft.

Rate of Climb, Time & Boost to Height
Level Speeds & Boost at Heights

For more of this report see HERE

N.3171 weighed in at 6,050 lbs. The 73 lb. pilot's armour found on more mature Spitfire Is was lacking. The aircraft was slightly down on power effecting top speed by about 2 mph. The engine limitations for the tests were:- Level Speeds - All-Out 5 minutes limit - 6.25 lbs./sq.inch, 3000 RPM; Climb - 6.25 lbs./sq.in. 2600 RPM Climbing 1/2 hour limit. Ironically, the day after this report was issued AP1590B/J.2-W was released, increasing the engine limitations to +12 lbs./sq.in, 3000 RPM. This allowed for an increase in speed below 10,000 feet of 28/34 mph.


Aeroplane and Armament Experimental Establishment
Boscombe Down

30 July 1940

Comparison of Performance of Rotol and DH Airscrews on Spitfire

            Both the aircraft are similar externally and are fitted with bullet proof windscreen and armour plating over the tank, etc.
 
            Aircraft R6774 is fitted with DH airscrew and N3171 with Rotol airscrew.
 
            It will be noted that these aircraft are about 12 miles an hour down in speed against the previously tested K9793, but the relative comparison remains. This loss in speed is accounted for, by 6 miles an hour for the bullet proof windscreen and 6 miles an hour due to loss in engine power.
 
            Level Speed miles per hour.

AeroplaneAltitude Feet

  1400016000Max. speed2000022000
R6774342349355 @ 17,800'350341
N3171336343354 @ 18,900'354352


            The above tests were all carried out using 87 octane fuel with boost limited to +6.25 lbs./sq.in. Climb figures were achieved using the 2600 rpm 1/2 hour climb limit. By the Battle of Britain all operational squadrons had changed over to 100 octane fuel and the engine limits on the Spitfires had been increased to +12 lbs./sq.in. 3,000 rpm with 1/2 hour climb limit increased to 2850 - 3000 rpm. Royal Aircraft Establishment figures for a Spitfire I using +12 lbs/sq. in. boost are 314 mph at Sea Level and 359 mph at a full throttle height of 11,500 feet.


Aeroplane and Armament Experimental Establishment
Boscombe Down

19 February 1941

Spitfire I X.4257 and R.6770.
Merlin III
(2 cannons and 4 Browning Guns.)
Brief Performance and Handling Trials

              Brief performance and handling trials were required on a Spitfire fitted with 2 cannons and 4 Browning guns. The tests were made on two aeroplanes Spitfire I X.4257 and Spitfire I R.6770.

Summary of Trials

Height
ft.
T.A.S.
m.p.h.
Time
From
Start
Min.
Rate
of
Climb
Ft./Min.
  2,000 0.92,295
  5,000 2.12,350
10,0003314.32,360
11,400 4.92,370
15,0003486.62,020
18,0003588.2 
20,0003539.41,535
25,000 13.2  1,050
30,000 19.6      570
Service ceiling = 34,700 ft.

Summary of Trials
Rate of Climb, Time to Height, & Boost
Level Speeds and Boost at Height


Aeroplane and Armament Experimental Establishment
Boscombe Down

10 June 1940

Messerschmidt 109 Fighter
Brief Handling Trials

Conclusions
 
            In general flying qualities the aeroplane is inferior to both the Spitfire and the Hurricane at all speeds and in all conditions of flight. It is much inferior at speeds in excess of 250 m.p.h. and at 400 m.p.h. recovery from a dive is difficult because of the heaviness of the elevator. This heaviness of the elevator makes all manoeuvres in the looping plane above 250 m.p.h. difficult including steep climbing turns. No difference was experienced between climbing turns to the right and left. It does not possess the control which allows of good quality flying and this is particularly noticeable in acrobatics.

For the full report see HERE


Royal Aircraft Establishment at Farnborough
June 1940
Spitfire IA K.9791 with Rotol constant speed propeller
Me 109E-3 Werk-Nr 1304

Comparitive trials between the Me.109 and "Rotol" Spitfire.


            1.     The trial commenced with the two aircraft taking off together, with the Spitfire slightly behind and using +6 1/4 lb boost and 3,000 rpm.

            2.     When fully airborne, the pilot of the Spitfire reduced his revolutions to 2,650 rpm and was then able to overtake and outclimb the Me 109. At 4,000 ft, the Spitfire pilot was 1,000 feet above the Me 109, from which position he was able to get on its tail, and remain there within effective range despite all efforts of the pilot of the Me 109 to shake him off.

            3.     The Spitfire then allowed the Me 109 to get on to his tail and attempted to shake him off this he found quite easy owing to the superior manoeuvrability of his aircraft, particularly in the looping plane and at low speeds between 100 and 140 mph. By executing a steep turn just above stalling speed, he ultimately got back into a position on the tail of the Me 109.

            4.     Another effective form of evasion with the Spitfire was found to be a steep, climbing spiral at 120 mph, using +6 1/4 boost and 2,650 rpm; in this manoeuvre, the Spitfire gained rapidly on the ME 109, eventually allowing the pilot to execute a half roll, on to the tail of his opponent.

            5.     Comparitive speed trials were then carried out, and the Spitfire proved to be considerably the faster of the two, both in acceleration and straight and level flight, without having to make use of the emergency +12 boost. During diving trials, the Spitfire pilot found that, by engageing fully coarse pitch and using -2lbs boost, his aircraft was superior to the Me 109.

For the report see HERE


Royal Aircraft Establishment, Farnborough
September 1940
Messerschmitt Me.109.
Handling and Manoeuvrability Tests

Conclusions

.......Take off is fairly straightforward. Landing is difficult until the pilot gets used to the aeroplane.

.......Longitudinally the aeroplane is too stable for a fighter. There is a large change in directional trim with speed. No rudder trimmer is fitted; lack of this is severely felt at high speeds, and limits a pilot's ability to turn left when diving.

.......Aileron snatching occurs as the slots open. All three controls are far too heavy at high speeds. Aerobatics are difficult.

.......The Me 109 is inferior as a fighter to the Hurricane or Spitfire. Its manoeuvrability at high speeds is seriously curtailed by the heaviness of the controls, while its high wing loading causes it to stall readily under high normal accelerations and results in a poor turning circle.

.......At 400 m.p.h a pilot, exerting all his strength, can only apply 1/5 aileron, thereby banking 45 deg. in about 4 secs. From the results Kb2 for the Me 109 ailerons were estimated to be -0.145.

.......The minimum radius of turn without height loss at 12,000 ft., full throttle, is calculated as 885 ft. on the Me 109 compared with 696 ft. on the Spitfire.

Spitfire and Me.109
Turns at minimum radius without height loss.
Both aeroplanes at full throttle at 12,000 ft.

 SpitfireMe.109
  Minimum radius of turn without loss of height.  ft.696885
  Cooresponding time to turn through 360 deg.  sec.1925
  Indicated airspeed Vi  m.p.h.133129
  A.S.I.R.  approx m.p.h.126118
  "g"2.652.1
  Angle of bank68 deg.62 deg.

Spitfire and Me 109. Diagrams of turning
ME 109 and Spitfire. Comparison of turning circles

Corresponding times to 45 deg. bank Me 109 and Spitfire.

Supplemental

Propellers

19 Squadron Operations Record Book, November 1939, Delivery of Rotol Constant Speed propeller equipped Spitfire
No 54 Squadron Operations Record Book. December 1939.  Re-equipped with Rotol prop, Dec. ORB, pg 2
Rotol Airscrews for Spitfire, Headquarters, Fighter Command, 16th June 1940
611 Operations Record Book, June 1940
609 Operations Record Book, June 1940
74 Operations Record Book, June 1940
92 Operations Record Book, June 1940
Spitfire Conversion of 2 Pitch De Havilland Airscrews to Constant Speed, HQ, Fighter Command, 17th June, 1940
De Havilland Constant Speed Airscrews, Loose Minute Sheet, 22.6.40
Spitfire I fitted with De Havilland Constant Speed Airscrew, 22.6.40
Spitfire I Airscrews, Ministry of Aircraft Production, 1st July 1940
"Spitfire" Conversion of Two Pitch De Havilland Airscrews to Constant Speed, Ministry of Aircraft Production, 11th July 1940
Pitch Panic, Flight, December 9th, 1943

+12 lbs boost & 100 octane fuel

RAE Chart of Spitfire I, Merlin III
Alec Harvey-Bailey, The Merlin in Perspective, (Rolls-Royce Heritage Trust, Derby, 1983), p. 155.
Rolls Royce Merlin engines- Max power level flight
Air Ministry Correspondence R.D.3.6. 14/11/39.
Merlin II and III - Use of +12 lb./sq.in. Boost Pressure - Alterations and Precautions, (March 20, 1940)
Handling of Merlin in Hurricane, Spitfire and Defiant Aircraft, H.C.T. Dowding, C-in-C Fighter Command, 1 August 1940.
A.P.1565A, Spitfire I Pilots Notes - Port cockpit view
Spitfire I Aeroplane. AP 1565A, Sect. 1-35: Boost cut-out EMERGENCY Control
Spitfire I Aeroplane. AP 1565A, Sect. 1-42: 100 octane fuel
Spitfire I Aeroplane. AP 1565A, Sect. 8-7.: Override control used with 100 octane fuel
AP 1590B Merlin II and III Aero-Engines - Fig.45 Sectional Perspective Views of Automatic Boost Control
A.P. 1565 A, The Spitfire I Aeroplane, 1st Edition June 1938, reprinted April 1940., Fig. 25. Engine Controls.
DRG.No. A.P.1590B/J.2/40 - Cut-out Valve for Boost Control
Merlin II and III Aero-Engines, Air Publication AP1590B (+12 lb.)
Emergency +12 lbs./sq. in. Boost Operation: Pilot's Notes, Merlin II, III and IV, 4th Edition, April 1940, page 6.
No 611 Operations Record Book, (21 March 1940)
No 74 Operations Record Book, (16 March 1940)
No 602 Operations Record Book, (16 February 1940)
David Ross, The Greatest Squadron of Them All, The Definitive History of 603 Squadron, RAauxAF, (Grub Street, London, 2003), p. 125.
Alec Harvey-Bailey, The Merlin in Perspective, (Rolls-Royce Heritage Trust, Derby, 1983), p. 85.
Alfred Price, The Spitfire Story, (Arms and Armour Press Ltd., London, 1986), p. 74.
Hundred Octane, Flight, No. 1631 Vol. XXXVII, The Outlook, March 28, 1940.
H. F. King, Fighter Station, With the Spitfires in Scotland, (Flight, No. 1631 Vol. XXXVII, March 28, 1940), pp. 290-295.
"Aero", Correspondance, (Flight, January 6th 1944), p. 22.
Air Commodore F. R. Banks, I Kept No Diary , Airlife Publications, Shrewsburg, 1978, App. II Fuel pp 234-236
W.G. Dudek and D. R. Winans, excerpt from AIAA Paper No. 69-779, Milestones in Aviation Fuels, (Esso Research and Engineering Company, New York 1969.) p. 319.
A. R. Ogston, History of Aircraft Lubricants (Society of Automotive Enginees, Inc. Warrendale, PA USA), p. 12.
Royal Air Force History - Spitfire,   Old Royal Air Force History Web page
The Daily Inspection of a Spitfire, Training film by the Royal Airforce - various stills. Spitfire I in pre Battle of Britain camoflage with 609 Squadron Codes marked for 100 octane fuel.
602 Squadron Spitfire I in pre Battle of Britain camoflage marked for 100 octane fuel.
Leo McKinstry, Hurricane, Victor of the Battle of Britain, (John Murrey Publishers, London, 2010), p. 87.
Leo McKinstry, Hurricane, Victor of the Battle of Britain, (John Murrey Publishers, London, 2010), p. 191.
Dilip Sarkar, How the Spitfire Won the Battle of Britain, (Amberley Publishing, Stroud, Gloucestershire, 2010), pp. 66-68.
Robert Schlaifer, Development of Aircraft Engines, (Harvard University, Boston, 1950), pp.220-223
The Trimpell Oil Refinery, Heysham Heritage Association
Al Deere, Combat Report - 26 May 1940
F/Lt Brian Lane, Combat Report - 26 May 1940
Assistant Chief of the Air Staff, 100 octane approval for Spitfire Squadrons, 24th September 1938
Headquarters Fighter Command, 100 'Octane' Fuel, 6th December, 1938.
100 Octane Fuel, Issue of, 12th December 1939
        See also 100 Octane Fuel - Issue of, 7 December 1939 & 100 Octane Fuel - Issue of, 9 December 1939
Gavin Bailey, The Narrow Margin of Criticality: The Question of the Supply of 100-Octane Fuel in the Battle of Britain, (English Historical Review Vol. CXXIII No. 501, Oxford University Press, 2008), p 406.
5th meeting of the the Co-ordination of Oil Policy Committee, 2 April 1940, TNA, PRO, AVIA 10/282.
7th meeting of the Co-ordination of Oil Policy Committee, 18 May 1940, TNA, PRO, AVIA 10/282
9th meeting of the Co-ordination of Oil Policy Committee, 7 Aug 1940, TNA, PRO, AVIA 10/282
D. Wood & D. Dempester, The Narrow Margin, (Paperback Library, New York, 1969), p. 87.
9th meeting of the Co-ordination of Oil Policy Committee, Revision of 100 Octane Fuel Statement
11th meeting of the Co-ordination of Oil Policy Committee, TNA, PRO, AVIA 10/282
Table III - Stocks and Total Receipts and Expenditure, War Cabinet Oil Position 12th March, 1942 (NA)  
Aviation Fuel and Oil, Total Weekly Issues, Air Ministry
Table II - Expenditure, War Cabinet Oil Position 12th March, 1942 (NA)  
Table II - Consumption, War Cabinet Oil Position 15th September, 1941 (NA)  
V. A. Kalichevsky, The Amazing Petroleum Industry, (Rheinhold Publishing Corporation, New York, 1943), p.7-8.
P/O John Freeborn, Combat Report - 24 May 1940
F/Lt Brian Lane, Combat Report - 26 May 1940
P/O M. P. Brown, Combat Report - 2 June 1940
F/Lt D. P. Kelly, Combat Report - 28 July 1940
F/LT. John Webster, Combat Report - 28 July 1940
F/LT. John Webster, Combat Report - 29 July 1940
P/O George Bennions, Combat Report - 28 July 1940
F/Lt George Gribble, Combat Report - 15 August 1940
F/Lt Robert Boyd, Combat Report - 18 August 1940
P/O Ronald Berry, Combat Report - 31 August 1940
Sgt. Jack Stokoe, Combat Report - 1 September 1940
P/O R.D. Elliott, Combat Report - 9 September 1940
F/O Brian Macnamara, Combat Report - 27 September 1940
F/O D.A.P. McMullen, Combat Report - 15-10-40

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