List of Air Ministry specifications

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This is a partial list of the British Air Ministry specifications for aircraft. A specification started from an Operational Requirement, abbreviated "OR", describing what the aircraft would be used for - this in turn led to a specification eg a two engined fighter with 4 machine guns. So for example, OR.40 for a heavy bomber led to Specification B.12/36. Aircraft manufacturers would design and build aircraft which the Ministry then bought for evaluation by the RAF. On very rare occasions, a manufacturer would design and build an aircraft using their own money as a "Private Venture". This would then be offered to the Ministry for evaluation. If the aircraft generated interest in the Ministry or RAF due to performance or some other combination of features then the Ministry might well bring out a specification based on the Private Venture aircraft.

The system of producing aircraft to a specification ran from 1920 to 1949 during which the Air Ministry was replaced by first the Ministry of Aircraft Production and then the Ministry of Supply. The system was applied to commercial aircraft as well - one of the last being the Bristol Brabazon. During the period, over 800 specifications were issued.

Specification designations

Each specification name usually followed a pattern. A leading letter was usually present to identify the aircraft purpose. The codes used included B for "heavy bomber", P for "medium bomber", F for "fighter" and A for "army co-operation". The second part was a number identifying it in sequence and then after the slash, the year it was formulated. Specifications were not always issued in sequence. Admiralty specifications, identified by the letter N, are included for completeness.

List of specifications (incomplete)

The names of the aircraft shown in the table are not necessarily those they carried when provided for evaluation. The names were usually chosen by the Air Ministry when they placed in production order.

Spec. OR Type Designs (accepted and tendered)
1/20 None First spec. issued: spares carrier Bristol Type 37 Tramp
16/23 None Spotting ship-plane Avro Bison
26/23 Two-seat long range day bomber Westland Yeovil, Hawker Horsley
4/24 Twin engined fighter armed with two 37 mm cannons Westland Westbury
23/25 Two-seat day bomber Westland Witch
F.9/26 None Day and night fighter Bristol Bulldog Mk.II, Gloster SS.18
F.20/27 Westland Interceptor
F.29/27 Fighter utilizing a 37 mm cannon from Coventry Ordnance Works Westland C.O.W. Gun Fighter
F.7/30 Monoplane fighter Supermarine Type 224, Westland F.7/30, Gloster Gladiator
G.4/31 Westland PV-7
R.24/31 General Purpose Open Sea Patrol Flying Boat Saunders Roe London
C.26/31 OR.4 Bomber-transport Bristol Bombay
B.9/32 OR.5 Twin-engine medium bomber Vickers Wellington, Handley Page Hampden
B.3/34 Twin-engine bomber Armstrong-Whitworth Whitley
P.4/34 Light bomber and close air support aircraft Hawker Henley
F.36/34 (modified by F.5/34) Eight-gun fighter with Rolls-Royce PV-12 engine Supermarine Spitfire, Hawker Hurricane
A.39/34 Army cooperation aircraft Westland Lysander
B.1/35 OR.19 Twin-engine medium bomber Armstrong Whitworth A.W.39, Handley Page H.P.55, Vickers Warwick
F.10/35 Drawn up for the Spitfire prototype Supermarine Spitfire
B.28/35 Drawn up for Bristol 142M Bristol Blenheim
F.37/35 OR.31 Fighter with cannon Westland Whirlwind, Hawker Hurricane with Oerlikon cannon
B.12/36 OR.40 Heavy bomber Short Stirling, Supermarine Type 316
R.1/36 OR.32 Small reconnaissance flying boat Saro Lerwick, Blackburn B-20
P.13/36 OR.41 Twin-engine medium bomber for "world-wide use" Avro Manchester, Handley Page H.P.56, Vickers Warwick with Rolls-Royce Vulture engines.
T.23/36 Multi-role crew trainer Airspeed Oxford
T.40/36 OR.44 Development and production of a trainer version of the Miles Hawk Miles Magister
F.9/37 OR.49 Twin-engine fighter Gloster G.39
F.18/37 Heavily armed interceptor Hawker Typhoon
S.24/37 OR.53 Naval torpedo/dive-bomber, reconnaissance Supermarine S.24/37, Fairey Barracuda
B.32/37 OR.44 Production contract for a four-engine version of the P.13/36 H.P.56 design Handley Page H.P.57 Halifax
E.28/39 Gloster E.28/39
B.1/40 OR.78 Twin-engine fast bomber De Havilland Mosquito
F.4/40 High-altitude fighter Westland Welkin
F.9/40 Written for Gloster F.9/40 Gloster Meteor
N.11/40 Naval Fighter Blackburn Firebrand F.1
F.19/40 Low-cost emergency production fighter Miles M.20
B.2/41 Bristol Blenheim replacement Bristol Buckingham
F.10/41 Written for Hawker Tempest Hawker Tempest
F.2/43 Written for Tempest Light Fighter Hawker Fury; cancelled at conclusion of hostilities.
O.5/43 Fairey Spearfish
N.7/43 carrier-based fighter Hawker Sea Fury
N.22/43 revision of N.7/43; carrier-based fighter Hawker Sea Fury
E.6/44 written for Saro SR.44 flying-boat fighter Saro SR.A/1
E.9/44 Flying wing bomber/airliner Armstrong Whitworth A.W.52
N.11/44 Long-range fighter with [[Rolls-Royce Eagle 22 piston engine Entered production as the Westland Wyvern with an Armstrong-Siddeley Python turboprop engine
C.16/46 Brabazon Committee Type IIB short-medium range airliner Armstrong Whitworth A.W.55 Apollo, Vickers Viscount
F.44/46 night/all weather fighter see F.4/48
B.35/46 Four engine jet bomber Avro Vulcan, Handley Page Victor
C.2/47 Brabazon Committee Type III airliner Bristol Britannia
F.3/48 written for P.1067, replaced F.43/46 Hawker P.1067 (Hawker Hunter)
F.4/48 OR.227. de Havilland DH.100, Gloster Javelin
B.9/48 Stop gap for B.35/46 designs Vickers Valiant
F.23/49 Jet fighter English Electric Lightning

Spec.	OR	Type	Designs (accepted and tendered)
1/20	None	First spec. issued: spares carrier	Bristol Type 37 Tramp
16/23	None	Spotting ship-plane	Avro Bison
26/23		Two-seat long range day bomber	Westland Yeovil, Hawker Horsley
4/24		Twin engined fighter armed with two 37 mm cannons	Westland Westbury
23/25		Two-seat day bomber	Westland Witch
F.9/26	None	Day and night fighter	Bristol Bulldog Mk.II, Gloster SS.18
F.20/27			Westland Interceptor
F.29/27		Fighter utilizing a 37 mm cannon from Coventry Ordnance Works	Westland C.O.W. Gun Fighter
F.7/30		Monoplane fighter	Supermarine Type 224, Westland F.7/30, Gloster Gladiator
G.4/31			Westland PV-7
R.24/31		General Purpose Open Sea Patrol Flying Boat	Saunders Roe London
C.26/31	OR.4	Bomber-transport	Bristol Bombay
B.9/32	OR.5	Twin-engine medium bomber	Vickers Wellington, Handley Page Hampden
B.3/34		Twin-engine bomber	Armstrong-Whitworth Whitley
P.4/34		Light bomber and close air support aircraft	Hawker Henley
F.36/34 (modified by F.5/34)		Eight-gun fighter with Rolls-Royce PV-12 engine	Supermarine Spitfire, Hawker Hurricane
A.39/34		Army cooperation aircraft	Westland Lysander
B.1/35	OR.19	Twin-engine medium bomber	Armstrong Whitworth A.W.39, Handley Page H.P.55, Vickers Warwick
F.10/35		Drawn up for the Spitfire prototype	Supermarine Spitfire
B.28/35		Drawn up for Bristol 142M	Bristol Blenheim
F.37/35	OR.31	Fighter with cannon	Westland Whirlwind, Hawker Hurricane with Oerlikon cannon
B.12/36	OR.40	Heavy bomber	Short Stirling, Supermarine Type 316
R.1/36	OR.32	Small reconnaissance flying boat	Saro Lerwick, Blackburn B-20
P.13/36	OR.41	Twin-engine medium bomber for "world-wide use"	Avro Manchester, Handley Page H.P.56, Vickers Warwick with Rolls-Royce Vulture engines.
T.23/36		Multi-role crew trainer	Airspeed Oxford
T.40/36	OR.44	Development and production of a trainer version of the Miles Hawk	Miles Magister
F.9/37	OR.49	Twin-engine fighter	Gloster G.39
F.18/37		Heavily armed interceptor	Hawker Typhoon
S.24/37	OR.53	Naval torpedo/dive-bomber, reconnaissance	Supermarine S.24/37, Fairey Barracuda
B.32/37	OR.44	Production contract for a four-engine version of the P.13/36 H.P.56 design	Handley Page H.P.57 Halifax
E.28/39			Gloster E.28/39
B.1/40	OR.78	Twin-engine fast bomber	De Havilland Mosquito
F.4/40		High-altitude fighter	Westland Welkin
F.9/40		Written for Gloster F.9/40	Gloster Meteor
N.11/40		Naval Fighter	Blackburn Firebrand F.1
F.19/40		Low-cost emergency production fighter	Miles M.20
B.2/41		Bristol Blenheim replacement	Bristol Buckingham
F.10/41		Written for Hawker Tempest	Hawker Tempest
F.2/43		Written for Tempest Light Fighter	Hawker Fury; cancelled at conclusion of hostilities.
O.5/43			Fairey Spearfish
N.7/43		carrier-based fighter	Hawker Sea Fury
N.22/43		revision of N.7/43; carrier-based fighter	Hawker Sea Fury
E.6/44		written for Saro SR.44 flying-boat fighter	Saro SR.A/1
E.9/44		Flying wing bomber/airliner	Armstrong Whitworth A.W.52
N.11/44		Long-range fighter with [[Rolls-Royce Eagle 22 piston engine	Entered production as the Westland Wyvern with an Armstrong-Siddeley Python turboprop engine
C.16/46	Brabazon Committee Type IIB	short-medium range airliner	Armstrong Whitworth A.W.55 Apollo, Vickers Viscount
F.44/46		night/all weather fighter	see F.4/48
B.35/46		Four engine jet bomber	Avro Vulcan, Handley Page Victor
C.2/47	Brabazon Committee Type III	airliner	Bristol Britannia
F.3/48		written for P.1067, replaced F.43/46	Hawker P.1067 (Hawker Hunter)
F.4/48	OR.227.		de Havilland DH.100, Gloster Javelin
B.9/48		Stop gap for B.35/46 designs	Vickers Valiant
F.23/49		Jet fighter	English Electric Lightning

List of Air Ministry specifications

Specification designations

List of specifications (incomplete)

Further reading