List of Air Ministry specifications
This is a partial list of the British Air Ministry specifications for aircraft. A specification stemmed from an Operational Requirement, abbreviated "OR", describing what the aircraft would be used for. This in turn led to the specification itself, e.g. a two-engined fighter with four machine guns. So for example, OR.40 for a heavy bomber led to Specification B.12/36. Aircraft manufacturers would be invited to present design proposals to the ministry, following which prototypes of one or more of the proposals might be ordered for evaluation. 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. The ministry may well release a specification based on the private venture aircraft if the plane aroused interest from the RAF or the ministry due to its performance or some other combination of features.
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 in 1940 and then the Ministry of Supply in 1946. The system was applied to commercial aircraft as well, two being the de Havilland Comet and Vickers Viscount. 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", e.g., B.12/36, P for "medium bomber", e.g., P.13/36, F for "fighter", e., F.10/35, and A for "army co-operation", e., A.39/34. The second part was a number identifying it in sequence and then after the slash, the year it was formulated, so in the example given above, B.12/36 signifies a specification for a heavy bomber, the twelfth specification of all types issued in 1936. Specifications were not always issued in sequence.Admiralty specifications were identified by the letter N, e., N.21/45, and experimental specifications identified by the letter E, e., E.28/39, with training aircraft signified by the letter T, e., T.23/31, and unpowered aircraft, signified by the letter X, e., X.26/40. The letter G signified a general-purpose aircraft, e.g., G.9/45, with an M being applied to aircraft intended for more than one specific purpose, e.g., M.15/35.
The letter C was applied to military transport aircraft, e.g., C.1/42, with the letter O used for a naval reconnaissance aircraft, e.g., O.8/38 – the letter S used for the more specialised role of naval spotting, i.e., observing and reporting back the fall of naval gunfire, e.g., S.38/34 – and R for a reconnaissance type – often a flying boat, e.g., R.3/33. Special purpose aircraft would be signified by a letter Q, this being used to specify aircraft such as target-tugs, radio-controlled target drones, etc., e.g., Q.32/55.
Sometimes the purpose for which an aircraft is used in service would change from that for which the specification to which it was designed was issued, and so there are some discrepancies and inconsistencies in designation, the Royal Navy in particular liking to specify multiple roles for its aircraft in an attempt to make the best use of the necessarily limited hangar space onboard its aircraft carriers. In this case this resulted in several types designed to specifications originally intended to signify the naval Spotting role also being used for other purposes, e.g., S.15/33, resulting in the Blackburn Shark and Fairey Swordfish, the latter aircraft being primarily utilised as a torpedo bomber. Similarly S.24/37, which produced the Fairey Barracuda, again primarily designed for spotting, the dive bomber/torpedo bomber requirements being regarded as secondary when the specification was issued, but for which roles it was almost exclusively subsequently used, the original spotting requirement having been made obsolete with the introduction of radar.
In addition, some specifications appear to have no letter prefix at all, e.g., 1/21, the [Vickers Virginia|Vickers Virginia III].
List of specifications (incomplete)
The names of the aircraft shown in the table are not necessarily those they carried when provided for evaluation as at this point an aircraft would usually be referred to as the Manufacturer ''X.XX/XX, e.g., the Avro B.35/46 – this is in addition to the manufacturer's own separate internal designation for the aircraft, e.g., Avro 698. With several manufacturers submitting designs to the same specification this could result in a number of different aircraft with the same X.XX/XX designation, e.g., Handley Page B.35/46, etc. Upon acceptance of the design the final service names would usually be chosen by the Air Ministry when they placed a production order, in the above B.35/46 cases, where two aircraft were accepted to this specification, Vulcan and Victor respectively.Upon entering service, in the absence of any already-planned variants a new type would initially have no mark number after the aircraft name, being simply referred to as the Manufacturer Service-name, e.g., the Avro Anson, however upon acceptance of a new variant the previous version automatically became the 'Mark I', so in the example given, the previous version of the Anson retrospectively became the Avro Anson Mk I upon acceptance of an Avro Anson Mk II. Sometimes planned variants would be later cancelled leading to 'missing' mark numbers, or the extent of the changes may have justified given the new variant a completely new name, e.g., the Hawker Typhoon II subsequently becoming the Hawker Tempest, or the Avro Lancaster B.IV & B.V entering service as the Avro Lincoln. In a few cases the same aircraft ordered with differing engines would be allocated separate names for each variant, e.g., Hawker Typhoon and Hawker Tornado, or the Handley Page Hampden and Handley Page Hereford. Typographical designation of mark numbers varied over time and inconsistencies are common, e.g., Mark II, Mk. II, II'', etc. Initially Roman numerals were used, changing to Arabic numerals post-World War II, e.g., Supermarine Spitfire Mk I to Supermarine Spitfire Mk 24.
Note 1: where possible mark numbers are given here in this list in the form that was used at the time of acceptance. Variations may be encountered due to changes in format/typographical convention.
Note 2: due to mergers and amalgamations within the UK aircraft industry sometimes the name of the manufacturer changed over time, e.g., English Electric later became part of the British Aircraft Corporation, so the English Electric Lightning then became the BAC Lightning; the British Aircraft Corporation itself and Hawker Siddeley then later merged and became British Aerospace, subsequently becoming BAe. Thus the previously mentioned Avro Vulcan was subsequently referred to as the Hawker Siddeley Vulcan; similarly, the Blackburn Buccaneer later became the Hawker Siddeley Buccaneer. Where possible, for clarity the aircraft in this list are listed under the ORIGINATING company's name or the name of the manufacturer under which it first entered production.
Specifications within the tables are listed in numerical order by year of issue; where a given number appears more than once, with one or more letter prefixes, the entries are presented in alphabetical order.
Air Board specifications (1917–1918)
In 1917, the Air Board began to issue specifications for new aircraft on behalf of the Royal Flying Corps and Royal Navy Air Service, with separate series for the RFC and Navy.| Spec | Type | Designs |
| A.1A | Single-seat fighter – Sopwith Camel replacement | Austin Osprey, Boulton & Paul Bobolink, Nieuport B.N.1, Sopwith Snipe |
| A.1C | Single-seat fighter – ABC Dragonfly engine, became RAF Type I specification. | Nieuport Nighthawk |
| A.2B | Single- or twin-engined day bomber | Airco DH.10 Amiens |
| A.3C | Heavy bomber – superseded by RAF Type V | Abandoned |
| Spec | Type | Designs |
| N.1A | Single seat land or ship-based fighter. | Beardmore W.B.IV, Beardmore W.B.V, Mann Egerton Type H |
| N.1B | Single-seat seaplane or flying boat fighter | Blackburn N.1B, Norman Thompson N.1B, Supermarine Baby, Westland N.1B, Wight Triplane Flying Boat |
| N.1B | Single seat torpedo bomber | Blackburn Blackburd, Short Shirl |
| N.2A | Two-seat floatplane scout | Fairey N.9, Fairey N.10, Short N.2A |
| N.2B | Two-seat floatplane bomber, bombload. | Fairey IIIB, Short N.2B |
| N.2C | Twin engined patrol flying boat | Norman Thompson N.2C |
RAF specifications (1918–1920)
1920–1929
| Spec | OR | Type | Designs |
| 1/20 | - | First spec. issued: spares carrier | Bristol Type 37 Tramp |
| 2/20 | 'Interim' single-engine heavy bomber | Avro Aldershot, de Havilland DH.27 Derby | |
| 3/20 | Single-seat deck-landing torpedo-carrier – Spec. superseded by 32/22 | Blackburn Dart (modified), Handley Page H.P.19 Hanley | |
| 4/20 | Long-distance photographic and reconnaissance aeroplane | Boulton & Paul Bolton | |
| 5/20 | Troop Carrier Biplane | Bristol Type 56, Vickers Victoria | |
| 6/20 | Vimy Ambulance | Vickers Vimy Ambulance | |
| 7/20 | Fleet reconnaissance and fleet spotting amphibian | Supermarine Seal II | |
| 8/20 | Three-seat reconnaissance aircraft for Army/Navy | Armstrong Whitworth Tadpole, Westland Walrus | |
| 9/20 | Medium range postal monoplane | Parnall Possum, Boulton & Paul Bodmin | |
| 10/20 | Cantilever monoplane | de Havilland Doncaster | |
| 11/20 | Medium Range Military Conversion of Postal Aeroplane | Parnall Possum, Boulton & Paul Bodmin | |
| 1/21 | Long-range bomber – Vickers Vimy replacement | Vickers Virginia III | |
| 2/21 | Experimental single-seat convertible biplane/monoplane fighter/interceptor/two-seat reconnaissance-fighter aircraft – written for Bullfinch | Bristol Bullfinch | |
| 3/21 | Naval Fleet spotter/reconnaissance aircraft | Avro Bison, Blackburn Blackburn | |
| 4/21 | Small troop carrier | Vickers Vernon | |
| 5/21 | Light day bomber – Airco DH.9A replacement | Fairey Fawn | |
| 6/21 | Postal aeroplane | Westland Dreadnought | |
| 7/21 | Single-Seat Ship Fighter | Parnall Plover | |
| 8/21 | Torpedo aeroplane | Blackburn T.4 Cubaroo | |
| 9/21 | Torpedo aeroplane | Blackburn Dart production | |
| 10/21 | Corps reconnaissance aircraft | Armstrong Whitworth Wolf, Hawker Duiker | |
| 11/21 | Vimy ambulance | Vickers Vimy ambulance | |
| 12/21 | Fleet spotting flying boat | English Electric Ayr | |
| 13/21 | Cantilever Monoplane | Handley Page H.P.20 | |
| 14/21 | Felixstowe F.5 replacement | Supermarine Scylla | |
| 13/21 | Cantilever monoplane | Handley Page H.P.20 | |
| 14/21 | Boat seaplane | Supermarine Scylla | |
| 15/21 | Twin-engined bomber | Boulton & Paul P.19 | |
| 16/21 | Biplane transport | Handley Page W.8b | |
| 17/21 | Biplane transport | Handley Page Type X, de Havilland DH.34 | |
| 18/21 | Passenger transport | Handley Page HP.18 Hanley / Handley Page HP.21 Hanley, de Havilland DH.32, Vickers Type 61 Vulcan | |
| 19/21 | Two-seat reconnaissance aircraft – Bristol F.2B Fighter replacement | Short Springbok | |
| 20/21 | High-altitude fighter | cancelled | |
| 21/21 | Spotting amphibian | Supermarine Seagull II | |
| 22/21 | Reconditioned F.2b | Bristol F.2b Fighter | |
| 1/22 | Passenger Aeroplane | Vickers Type 170 Vanguard | |
| 2/22 | Amphibians for use in the Middle East | Vickers Viking V | |
| 3/22 | Two-seat fighter/reconnaissance powered by a supercharged engine – Bristol Fighter replacement | Bristol Type 84 Bloodhound | |
| 4/22 | Reconditioning of DH.10 | Airco DH.10 Amiens | |
| 5/22 | Spare wing | de Havilland DH.29 Doncaster | |
| 6/22 | Naval carrier fighter with interchangeable wheel and float undercarriages using Armstrong Siddeley Jaguar or Bristol Jupiter engine – Nieuport Nightjar replacement | Fairey Flycatcher, Parnall Plover | |
| 7/22 | Army reconnaissance aircraft | Hawker Duiker | |
| 8/22 | Corps reconnaissance aircraft | Armstrong Whitworth Wolf | |
| 9/22 | New tail unit and trial | de Havilland DH.29 Doncaster | |
| 10/22 | Metal-winged DH.9a | Airco DH.9a | |
| 11/22 | Reconditioning of DH.9a | Airco DH.9a | |
| 12/22 | Single-engined goods carrier | Vickers Type 63 Vulcan | |
| 13/22 | Reconditioning of Snipe | Sopwith Snipe | |
| 14/22 | High performance landplane | Armstrong Whitworth Siskin III | |
| 15/22 | Modifications to Hanley | Handley Page HP.19 Hanley II | |
| 16/22 | Long range torpedo bomber to carry 21 inch torpedo | Blackburn Cubaroo, Avro 557 Ava | |
| 17/22 | Amphibian floatplane | Not proceeded with | |
| 18/22 | Amphibian seaplane | Not proceeded with | |
| 19/22 | Night bombing landplane | Not proceeded with | |
| 20/22 | Coast patrol seaplane | English Electric P.5 Cork | |
| 21/22 | Twin-engined amphibian flying boat for civil operations – see also R.18/24 | Supermarine Swan | |
| 22/22 | Two-seat fighter/reconnaissance powered by a supercharged engine – Bloodhound three aircraft order – revised from 3/22 | Bristol Type 84 Bloodhound | |
| 23/22 | Amphibian floatplane | Not proceeded with | |
| 24/22 | Amphibian seaplane | Not proceeded with | |
| 25/22 | Single-seat night interceptor fighter | Hawker Woodcock | |
| 26/22 | Cantilever Monoplane for Civil Purposes | Not proceeded with | |
| 27/22 | Three-engined Mail Carrying Landplane | Not proceeded with | |
| 28/22 | Rebuilding and Modification of the Doncaster | De Havilland DH.29 Doncaster | |
| 29/22 | Postal Monoplane | Westland Dreadnought | |
| 30/22 | Boulton & Paul Bugle | ||
| B.30/22 | Heavy bomber – written for Bugle II production order but Sidestrand also apparently designed to this spec. | Boulton & Paul Bugle II, Boulton Paul Sidestrand | |
| 31/22 | Four-seat heavy night-bomber | Handley Page Hyderabad | |
| 32/22 | Single-seat deck-landing torpedo-carrier – Spec. supersedes 3/20 | Blackburn Dart II, Bristol Brandon | |
| 37/22 | Three-seat deck landing reconnaissance aircraft – Blackburn Blackburn / Avro Bison replacement | Avro Type 550, Blackburn Airedale, Hawker Hedgehog | |
| 38/22 | General purpose seaplane/landplane | Fairey IIID | |
| 40/22 | Transport aeroplane – civil airliner – larger version of de Havilland DH.34 | de Havilland Highclere | |
| 41/22 | 'Middle East type transport aeroplane' – civil airliner | Armstrong Whitworth Argosy, de Havilland Hercules | |
| 43/22 | Vickers Vernon II | ||
| 44/22 | Single-engined long-range reconnaissance seaplane – intended for round-the-World flight | Fairey Fremantle | |
| 46/22 | Three-seat fleet-spotter amphibian | Vickers Vanellus | |
| 9/23 | Superseded by 14/24 | Blackburn Iris | |
| 13/23 | Supermarine Seagull II | ||
| 16/23 | - | Spotting ship-plane | Avro Bison |
| 19/23 | Fighter/interceptor – improved Siskin III | Armstrong Whitworth Siskin IIIA | |
| 21/23 | Fleet two-seat torpedo bomber | Avro Buffalo, Blackburn Ripon, Handley Page H.P.31 Harrow | |
| 23/23 | Coastal patrol and anti-submarine flying-boat | English Electric Kingston | |
| 25/23 | Fleet two-seat torpedo bomber/bomber | Handley Page H.P.25 Hendon | |
| 26/23 | Two-seat long-range day-bomber | Bristol Berkeley, Handley Page H.P.28 Handcross, Hawker Horsley, Westland Yeovil | |
| 28/23 | Long-range bomber – Virginia production order | Vickers Virginia | |
| 37/23 | Single-engined fighter/interceptor – improved Grebe | Gloster Gamecock | |
| 38/23 | Twin-engined Night Bombing Landplane | Vickers Vimy | |
| 39/23 | Single-engined Single-Seater Racing Seaplane | Gloster II | |
| 40/23 | Single-engined Single-Seater Racing Seaplane | Supermarine S.4 | |
| 41/23 | Fitting of Handley Page Slotted Wings to the Bristol Fighter Aircraft | Bristol F.2B | |
| 42/23 | Amphibian Alighting Gear for Fairy Flycatcher I | Fairey Flycatcher | |
| 43/23 | Special Wings to Aerofoil Section of R&M 322 for Blackburn Dart | Blackburn Dart | |
| 44/23 | Light Aeroplane | De Havilland DH.53 Humming Bird | |
| 45/23 | Two-seater Fighter Reconnaissance Landplane | Vickers Venture | |
| 1/24 | Three-seat fleet reconnaissance seaplane and amphibian | Parnall Pike, Short S.6 Sturgeon, Bristol Type 87 | |
| 2/24 | Light aeroplane | Cancelled | |
| 3/24 | Single-seat high-performance landplane | Hawker Woodcock II | |
| 4/24 | "Twin-Engined Home Defence Fighter" armed with two 37 mm cannons | Westland Westbury Bristol Bagshot | |
| 5/24 | Advanced landplane, convertible to a seaplane, trainer for RAF and deck-landing trainer for FAA | Cancelled, replaced by 5A/24 | |
| 5A/24 | Floatplane trainer | Vickers Vendace, Blackburn Sprat, Parnall Perch | |
| 6/24 | Single-seat fighter | Fairey Flycatcher | |
| 7/24 | 'High powered single-seater fighter landplane' | Avro Avenger, Fairey Firefly I, Fairey Fox, Gloster Gorcock, Hawker Hornbill | |
| 8/24 | Army co-operation aircraft | de Havilland Dingo | |
| 9/24 | Twin engine medium day-bomber – Sidestrand II production order – see also 25/27 | Boulton Paul Sidestrand II | |
| 10/24 | Fleet spotting ship-plane | Blackburn Blackburn | |
| 11/24 | Fleet spotting ship-plane | Avro Bison II | |
| 12/24 | Long-range bomber – Virginia production order | Vickers Virginia | |
| 13/24 | Patrol flying boat | Blackburn Iris III, Short Singapore | |
| 14/24 | Three-engined boat seaplane | Blackburn Iris, Saunders Valkyrie | |
| 15/24 | Four-seat heavy night-bomber – initial production batch of Hyderabads | Handley Page Hyderabad I | |
| 16/24 | Submarine-borne reconnaissance seaplane | Parnall Peto | |
| 17/24 | Single-seat high-speed fighter landplane | Gloster Guan | |
| 18/24 | Twin-engined amphibian flying boat – military version of boat ordered to 21/22 | Supermarine Southampton | |
| 19/24 | Three-seat spotter/reconnaissance /two-seat GP aircraft with interchangeable land & float U/C and folding wings | Fairey IIIF | |
| 20/24 | All-metal monoplane flying boat | Beardmore Inverness | |
| 21/24 | Single-seat boat seaplane for storage in restricted space | Parnall Prawn | |
| 22/24 | Three-engine boat seaplane | Saunders Valkyrie | |
| 23/24 | Twin engine civil airliner | Handley Page H.P.32 Hamlet | |
| 24/24 | Conversion of Bison I to Bison Ia | Avro Bison | |
| 25/24 | Single-seater, high-speed fighter landplane | Hawker Heron | |
| 26/24 | Three-engined land-plane for duties in the Middle East | Cancelled | |
| 27/24 | Twin engine single-seat interceptor/night fighter | Boulton Paul Bittern | |
| 28/24 | Day and night fighter – Armstrong Whitworth Siskin replacement | Armstrong Whitworth Starling | |
| 29/24 | Twin-engined boat amphibian with Lynx engines | Supermarine Seamew | |
| 30/24 | Two-seat reconnaissance/army co-operation aircraft | de Havilland Hyena, Short Chamois, Vickers Vespa | |
| 31/24 | Twin-engined boat amphibian with Lynx engines | Saunders Medina | |
| 32/24 | Training landplane with Lynx engines – replaced by 3/27 | Avro 504N | |
| 33/24 | Three-engined boat seaplane for civil use | Not issued | |
| 34/24 | Freight carrying landplane | Vickers Vellore, Gloucester Goodwood | |
| 35/24 | Three-engine landplane for Middle East transport | Armstrong Whitworth Argosy | |
| 11/25 | Reconnaissance flying boat | Supermarine Southampton | |
| 12/25 | Two-seater fleet reconnaissance aircraft | Cancelled | |
| 13/25 | Troop carrier | Vickers Victoria III | |
| 14/25 | Demonstration flight of Cierva Autogiro | Cierva C.6A | |
| 17/25 | Naval single-seater fighter of all-metal stressed-skin construction with interchangeable wheel and float U/C powered by Lynx engine | Avro 584 Avocet, Vickers Vireo | |
| 20/25 | Army co-operation aeroplane – Bristol Fighter/DH.9A replacement | Armstrong Whitworth Atlas, Bristol Boarhound | |
| 23/25 | Two-seat day-bomber, reconnaissance & coastal torpedo-bomber | Blackburn Beagle, Gloster Goring, Handley Page H.P.34 Hare, Hawker Harrier, Westland Witch | |
| 24/25 | High altitude bomber – Hawker Horsley replacement | Blackburn Beagle, Handley Page H.P.34 Hare, Vickers Vildebeest | |
| 7/26 | Twin-float high-speed monoplane seaplane for 1927 Schneider Trophy competition | Short Crusader | |
| F.9/26 | - | Day and night 'zone' fighter – no design accepted and Spec. superseded by F.20/27 | Armstrong Whitworth Starling II, Blackburn Blackcock / Turcock, Boulton Paul Partridge, Bristol Bulldog Mk.I, Bristol Bullpup, Gloster Goldfinch, Gloster SS.18, Hawker Hawfinch, Vickers Type 141 |
| 10/26 | Long-range bomber – Virginia production order | Vickers Virginia | |
| 12/26 | Fast two-seat day bomber of all-metal construction using Rolls-Royce F.XIB engine | Avro Antelope, Hawker Hart, Fairey Fox IIM | |
| 14/26 | Passenger flying boat | Short Calcutta | |
| 21/26 | Naval Fleet fighter – see also N.21/26 | Parnall Pipit, Vickers Type 141, Vickers Type 177 | |
| N.21/26 | Naval Fleet fighter – see also 21/26 | Armstrong Whitworth Starling II, Armstrong Whitworth A.W.16, Blackburn Blackcock/Turcock, Fairey Firefly III, Gloster Gnatsnapper, Hawker Hoopoe, Vickers Type 177 | |
| O.22/26 | Naval high-speed, two-seat, Fleet fighter/reconnaissance | Blackburn Nautilus, Fairey Fleetwing, Handley Page H.P.37F, Hawker Osprey, Short Gurnard | |
| R.4/27 | Maritime patrol flying boat | Saunders Severn | |
| R.5/27 | Reconnaissance flying boat | Blackburn Sydney | |
| 8/27 | Long-range bomber – Virginia production order | Vickers Virginia | |
| F.10/27 | Single-seat fighter armed with six machine guns | Saunders A.10 | |
| B.19/27 | Twin engine night-bomber – Virginia/Hinaidi replacement – Hendon winner but introduction delayed so runner-up accepted | Avro 557 Ava, Fairey Hendon, Handley Page Heyford, Vickers Type 150, Vickers Type 163, Vickers Type 195, Vickers Type 225, Bristol Type 108 | |
| C.20/27 | Transport version of Handley Page Hyderabad / Handley Page Hinaidi – Chitral/Clive | Handley Page Clive | |
| F.20/27 | 'Interception single-seat fighter' to overtake in shortest time an enemy aircraft flying at 150 mph at 20,000 ft | Armstrong Whitworth Starling II, Bristol Bulldog Mk.II, de Havilland DH.77, Fairey Firefly II, Hawker Fury, Saunders A.10, Vickers Jockey, Westland Interceptor | |
| B.22/27 | Three engine night-bomber – abandoned due to delays and replaced by B.19/27 | Boulton Paul P.32, de Havilland DH.72 Canberra | |
| 25/27 | Twin engine medium day-bomber – Sidestrand II production order – see also 9/24 | Boulton Paul Sidestrand II | |
| 26/27 | General purpose aircraft – D.H.9A replacement | Bristol Beaver, de Havilland Hound, Fairey Ferret, Gloster Goral, Vickers 131 Valiant, Vickers Venture, Vickers Vixen, Westland Wapiti | |
| F.29/27 | Fighter utilizing a 37 mm cannon from Coventry Ordnance Works to meet similar requirements as F.20/27 | Vickers Type 161, Westland C.O.W. Gun Fighter, Bristol Type 112 | |
| 33/27 | 'Postal Aircraft' – experimental very-long range aeroplane for world distance-record attempt | Fairey Long-range Monoplane | |
| M.5/28 | Torpedo bomber – Spec superseded by M.1/30 | Handley Page H.P.41 | |
| R.6/28 | Patrol/reconnaissance flying boat | Short Sarafand | |
| 8/28 | Racing seaplane for 1929 Schneider Trophy using Rolls-Royce R engine, for use by RAF High Speed Flight | Supermarine S.6 | |
| 13/28 | Long-range bomber – Virginia production order | Vickers Virginia | |
| C.16/28 | Bomber-transport capable of carrying 30 fully armed troops, or their equivalent in cargo or bombs, for a distance of nonstop | Gloster TC.33, Handley Page H.P.43, Vickers Type 163, Bristol Type 115, Bristol Type 116 | |
| F.17/28 | Bulldog II production order | Bristol Bulldog Mk.II | |
| 21/28 | High-speed mailplane for Imperial Airways | Boulton & Paul Mailplane, Boulton Paul P.71A | |
| 1/29 | General purpose aircraft | Westland Wapiti | |
| 2/29 | Two-seat carrier-borne torpedo-bomber | Blackburn Ripon IIA | |
| 3/29 | Troop transport aircraft | Handley Page Clive II | |
| 4/29 | Ab initio trainer – Moth with de Havilland Gipsy I order | de Havilland Gipsy Moth | |
| 5/29 | Elementary trainer | Hawker Tomtit | |
| 6/29 | General purpose landplane | Blackburn C.A.15C, Boulton & Paul P.42, Westland Limousine V | |
| 7/29 | Troop carrying aeroplane | Vickers Victoria V | |
| 8/29 | Single-seat fighter | Armstrong Whitworth Siskin IIIA | |
| 9/29 | Day bomber | Hawker Hart | |
| 10/29 | Medium day-bomber | Boulton Paul Sidestrand III | |
| 11/29 | Day and night fighter | Bristol Bulldog IIA | |
| 12/29 | Spotter reconnaissance aeroplane for the Fleet Air Arm | Fairey IIIF | |
| 13/29 | Heavy night-bomber | Handley Page Hinaidi II | |
| 14/29 | Army co-operation aircraft | Cancelled | |
| 15/29 | General purpose aircraft | Cancelled | |
| 16/29 | Experimental tailless aircraft | Westland-Hill Pterodactyl IV | |
| 17/29 | All-metal torpedo-bomber | Hawker Horsley | |
| 18/29 | General reconnaissance flying boat – military version of Short S.8 Calcutta | Short Rangoon |
Post 1949 specifications. Air Staff Operational Requirements/targets
| Spec | OR | Year | Type | Related aircraft |
| ER.100 | 1950 | Experimental low-speed research aircraft with highly-swept wings in support of F23/49 | Short SB.5 | |
| M.101 | NA.28 | 1950, 1952 | Three-seat anti-submarine aircraft | Fairey Firefly AS.7 |
| N102 | 1950 | Two-seat trainer for Royal Navy | Boulton Paul Sea Balliol | |
| ER.103 | 1950 | Delta-wing research aircraft capable of Mach 1.5 | Fairey Delta 2 | |
| B.104 | OR.285 | 1950 | Low-level, medium-range Pathfinder aircraft for Bomber Command | Vickers Valiant B.2 |
| F.105D | OR.288/2 | 1951 | Swept wing day-fighter development of E41/46 for RAF | Supermarine Swift |
| F.105D2 | High performance derivative of Supermarine Swift | Supermarine Type 545 | ||
| F.105P2 | OR.288/3 | 1951 | Production of Supermarine Swift Marks 1–4 | Supermarine Swift |
| N.105D&P | NA.34 | 1952 | Navalised version of Supermarine Swift | Supermarine Type 548 |
| FR.105D&P | OR.308 | 1952 | Fighter-reconnaissance version of Supermarine Swift | Supermarine Swift FR.5 |
| PR.105D&P | OR.310 | 1952 | Medium/high-altitude reconnaissance version of Supermarine Swift | Supermarine Swift PR.6 |
| F.105D&P3 | 1953 | Supermarine Swift armed with Fairey Fireflash air-to-air missiles | Supermarine Swift F.7 | |
| H.106 | 1951 | General purpose helicopter – update of E.34/46 | Bristol Sycamore Mark 3 | |
| A.106P | 1951 | Production of Sycamore helicopter for Army | Bristol Sycamore HC.11 | |
| HR.106P – HR.106P5 | OR.304 | 1952–53 | Air-sea rescue helicopters for RAF and RAAF | Bristol Sycamore HR.12, HR.50, HR.13, HR.51, HR.14 |
| N.107 | NA.30 | 1951 | Naval all-weather fighter | de Havilland Sea Venom |
| F.108 | OR.265/2 | 1951 | Night fighter for RAF | de Havilland Venom NF.2 |
| UB.109 | AST.1097 | 1951–1953 | Expendable Bomber | Bristol Type 182, Vickers Type 655, Boulton Paul P123 |
| ER.110T | 1951 | Variable sweepback research monoplane | Armstrong Whitworth AW.59, Blackburn B.90, Boulton Paul P.121, Bristol Type 183, Saro P.149 | |
| F.111P | OR.265 | 1951 | Interim jet-powered night fighter for RAF | de Havilland Vampire NF.10 |
| T.111P | 1952 | Two-seat trainer version of de Havilland Vampire | de Havilland Vampire T.11 | |
| T.111P2 | NA.36 | 1952 | Two seat Vampire Trainer for RN | de Havilland Sea Vampire T.22 |
| R.112D | OR.231/3 | Reconnaissance flying boat | Short PD.3 | |
| N.113D&P | NA.17 | 1951–1953 | Supermarine N.9/47 Development and Production | Supermarine Type 544 Scimitar F.1 |
| N.114T | NA.14 | 1951 | All-weather Naval Fighter | Armstrong Whitworth AW.165, Blackburn B.89, Fairey N.114T, Saro P.148, Short PD.5, Westland N.114T |
| C.115P | OR.266/2 | 1951 | VIP version of Handley Page Hastings | Handley Page Hastings C.4 |
| T.116D | OR.278 | 1951 | Trainer version of de Havilland DH.110 for RAF | |
| F118D, F118P | c. 1953 | All-weather fighter | "Super Javelin" Gloster Javelin with new wing. Gloster GA.6/P.356 | |
| F.119D | 1952 | Hawker Hunter derivative with reheated Rolls-Royce Avon RA.14R and increased wingsweep | Hawker P.1083 | |
| U.120D | 1951 | Remotely piloted target aircraft | ML U.120 | |
| C.121P | OR.300 | 1952 | Communication aircraft for RAF | Percival Pembroke C.1 |
| ID.122D&P | 1953 | Intruder version of Canberra bomber | English Electric Canberra B8 | |
| PR.122P | 1954 | High-altitude reconnaissance version of Canberra | English Electric Canberra PR.9 | |
| M.123 | NA.32 | 1954 | Light carrier-based anti submarine aircraft | Short Seamew |
| F.124T | OR.301 | 1952 | Rocket fighter – superseded by F.137D and F.138D for Avro and Saro designs | Avro 720, Blackburn B.97, Boulton Paul P.122, Bristol Type 178, Fairey F.124T, Hawker P.1089, Saro P.154, Short PD.7, Westland F.124T |
| EH.125 | 1952 | Experimental rotor-blade tip-jet powered helicopter | Percival P.74 | |
| B.126T | OR.314 | 1952 | Low-level bomber – cancelled 1954 | Avro 721, Bristol 186, Handley Page H.P.99, Short PD.9. |
| H.127 | NA.37 | 1952 | Westland-Sikorsky WS-55 | |
| HCC.127 | 1958 | Whirlwind helicopter for Queens Flight | Westland Whirlwind HCC 8 | |
| B.128P | OR.229/3 | 1952 | Production of Victor B.1 bomber | Handley Page Victor B.1 |
| B.128P2 | 1958 | Improved version of Victor bomber | Handley Page Victor B.2 | |
| B.129P | 1952 | Production of Vulcan B.1 | Avro Vulcan B.1 | |
| B.129P2 | 1958 | Improved version of Avro Vulcan | Avro Vulcan B.2 | |
| T.130D&P | 1952 | Conversion of unsold Handley Page Marathon airliners to navigation trainers for RAF | Handley Page Marathon T.11 | |
| N.131T | 1952 | All weather fighter for Royal Navy – no further action | de Havilland DH.116 | |
| C.132 | OR.315 | 1952 | Long-range jet transport | Vickers V.1000 |
| ER.133 | Rocket-powered research aircraft – not issued | Bristol Type 178 | ||
| ER.134D | 1954 | High-speed research aircraft | Bristol Type 188 | |
| F.137D | OR.301/2 | 1953 | Rocket powered interceptor – written around Avro 720 | Avro 720 |
| F.138D | OR.301/2 | 1953 | Mixed rocket-jet interception fighter – written around SR.53 | Saunders-Roe SR.53 |
| F.139 | NA.38/3 | 1954 | Two-seat naval all-weather fighter | de Havilland Sea Vixen FAW.1 |
| D.140P | 1953 | Pilotless target conversion of Fairey Firefly | Fairey Firefly U.8 | |
| OR.323 | 1953 | Transport aircraft – Hastings and Valetta replacement. Vickers 799 selected but requirement superseded by C.195/OR.344 written around Armstrong Whitworth AW.650 Argosy | Armstrong Whitworth AW.55 and AW.56, Aviation Trader ATL-95, Blackburn B-104, Bristol Type 179, Vickers Type 799 | |
| RH.142D | OR.334 | 1953 | VTOL transport aircraft | Fairey Rotodyne; later cancelled |
| ER.143 | 1953 | Experimental direct jet-lift VTOL research aircraft | Short SC.1 | |
| HR.144 | OR.31934408 | 1953 | Ultra Light Helicopter | Fairey ULH |
| HR.146D&P | NA.43 | 1953 | Development of Bristol 173 for the Royal Navy. Cancelled in favour of Westland Wessex. | Bristol Type 191 for the Royal Navy |
| T147T | OR.318 | Advanced jet trainer – not progressed | Avro Type 725 | |
| M.148 | NA.39 | 1954 | Low level naval strike aircraft | Blackburn Buccaneer S.1, Armstrong Whitworth AW.168, Fairey M.148T, Hawker P.1108, Short PD.13, Westland M.148T |
| HR.149D&P | ASR.326 | 1955 | Anti-submarine development of the Bristol 173 for RAF. | Bristol Type 191 |
| H.150D&P | OR.325 | Twin-rotor transport helicopter for RAF | Development of the Bristol 191 for the Royal Air Force | Bristol Type 192 as the Westland Belvedere HC.1 |
| C.151 | Communications aircraft | de Havilland Heron C.2 and C.3 | ||
| F.153D | 1955 | All weather fighter | "Thin Wing Gloster All Weather Fighter". Updating of F.118. Gloster P.376 | |
| AEW.154 | NA.64 | 1955 | Carrier-based Airborne Early Warning aircraft | Fairey Gannet AEW.3 |
| F.155T | OR.329 | 1955 | High-altitude fighter – Fairey Delta III selected but project cancelled in 1957 | Armstrong Whitworth AW.169, de Havilland DH.117, English Electric P.8, Fairey Delta III, Hawker P.1103, Saro P.187, Vickers Type 559 |
| R.156T | OR.330 | 1954 | High-altitude supersonic reconnaissance aircraft | Avro 730, English Electric P.10, Handley Page HP.100, Short PD.12, Vickers SP.4 |
| RB.156T | OR.330/2 | 1956 | Reconnaissance-bomber – development of R.156T – cancelled 1957 | Avro 730 |
| T.157D&P | 1955 | Two-seat trainer version of Hawker Hunter for RAF | Hawker Hunter T.7 | |
| N.157D&P | 1957 | Two-seat trainer version of Hawker Hunter for Royal Navy | Hawker Hunter T.8 | |
| C.159P | 1955 | Purchase of single example of Bristol Freighter for A&AEE | Bristol Freighter Mk. 31 | |
| ER.161 | 1955 | Research aircraft for narrow delta wings | Armstrong Whitworth AW.171, Armstrong Whitworth AW.172 | |
| F.162D | 1955 | Light jet fighter for RAF – development of Folland Midge | Folland Gnat F.1 | |
| H.163 | 1955 | Light helicopter for AOP duties for Army and training for RAF | Saunders-Roe Skeeter AOP.10, T.11, AOP.12, T.13 | |
| ER.163 | 195? | Experimental Fairey Delta 2 with de Havilland Gyron engine – later cancelled | Fairey Delta 2 | |
| FR.164D&P | 1958 | Fighter-reconnaissance version of Hawker Hunter | Hawker Hunter FR.10 | |
| R.165D | Specification for radios and radar for de Havilland Comet C.2. Not proceeded with. | Possibly related to de Havilland Comet 2R ELINT aircraft | ||
| ER.166D | 1955 | Jet-propelled lift-fan VTOL research aircraft – not proceeded with | Boulton Paul P.132 | |
| F.167D | Hawker Hunter with AI.20 radar and de Havilland Firestreak air-to-air missiles. One aircraft built | Hawker Hunter | ||
| D.168D&P | 1955 | Conversion of Fairey Firefly AS.4 and AS.5 to pilotless target drone | Fairey Firefly U.9 | |
| D.169D&P | 1955 | Conversion of Canberra B2 to pilotless target drone | English Electric Canberra U.10, U.14 | |
| HAS.170D&P | NA.43 | 1956 | Anti-submarine helicopter for Royal Navy | Westland Wessex HAS.1 |
| D.171D&P | 1955 | Conversion of Avro Lincoln to pilotless target drone – Only two aircraft converted | Avro Lincoln U.5 | |
| F.172D | Lightweight supersonic fighter – variant of Folland Gnat with thin wing, afterburning engine and air-to-air missiles. Unbuilt | Folland Gnat F.2 | ||
| D.173D&P | Conversion of Gloster Meteor F.4 to pilotless target drones by Flight Refuelling Ltd | Gloster Meteor U.15 | ||
| D.174D&P | 1956 | Conversion of Gloster Meteor F.8 to pilotless target drones by Flight Refuelling Ltd | Gloster Meteor U.16 | |
| ER.175 | Proposed conversion of de Havilland Canada DHC-3 Otter with jet flaps. Unbuilt | |||
| C.176 | 1956 | Long range transport aircraft for RAF – military version of Bristol Britannia airliner | Bristol Britannia C.1 | |
| F.177D | OR.337 / NA.47 | 1956 | Mixed power interceptor for RAF and Royal Navy | Saunders-Roe SR.177 |
| T.178D&P | 1957 | Dual control trainer version of English Electric Lightning | English Electric Lightning T.4 | |
| TT.179D | Target-tug conversion of Meteor night fighter for RAF. Not proceeded with, but similar conversions made for RN as TT.20 | Gloster Meteor TT.20 | ||
| ER.180D | 1956 | Sub-scale model of Avro 730 high-altitude reconnaissance-bomber to aid in development. Cancelled in 1957 with Avro 730 | Avro 731 | |
| ER.181T | Proposed high-speed research aircraft. Not proceeded with. | |||
| T.182D | Proposed conversion of English Electric Canberra B.2 to radar trainer. Unbuilt. | |||
| ER.183D | Proposed conversion by Handley Page of Jet Provost trainer for boundary layer control research. Unbuilt | Handley Page HP.103 | ||
| ER.184D | 1957 | Conversion by Marshall's of Cambridge of Auster T.7 to boundary layer control research aircraft. One aircraft converted. | Marshalls MA.4 | |
| T.185D | 1958 | Two seat trainer version of Folland Gnat for RAF. | Folland Gnat T.1 | |
| C.186P | 1957 | Twin-engined STOL transport for RAF | Scottish Aviation Twin Pioneer | |
| D.187D&P | Proposed conversion of Gloster Meteor NF.11 to pilotless target drone. Unbuilt. | |||
| ER.189D | 1959 | Purpose-built research aircraft for blown flaps. One example built. | Hunting H.126 | |
| CC.190D | Evaluation of Edgar Percival EP.9 for Army Air Corps. Two tested, but no further purchases. | Edgar Percival EP.9 | ||
| HAS.191D | 1958 | Fairey Ultra Light Weight helicopter for anti-submarine and communications use from small ships. Two evaluated. No production. | - | |
| RB.192D | GOR.339 / OR.343 | 1957 | STOL Tactical-Strike/Reconnaissance aircraft capable of Mach 2 and suitable for operation from unpaved strips – Canberra replacement. TSR.2 selected. | Avro 738, Bristol Type 204, English Electric P.17A, Vickers Type 571, BAC TSR.2 |
| ER.193D | 1959 | Conversion of Fairey Delta 2 with new Ogee delta wing. Specification developed into ER.221 | BAC.221 | |
| HAS.194D | 1959 | Small shipboard anti-submarine helicopter | Saunders-Roe P.531 | |
| C.195 | OR.344 | 1959 | Replacement for Hastings and Valetta. Requirement replaced OR.323 and written around military derivative of Armstrong Whitworth AW.650 Argosy. | Armstrong Whitworth AW.660 Argosy |
| X.197T | 1959 | Research glider with slender delta wing – abandoned in favour of powered ER.197D. | Avro 759, Bristol Type 215, Fairey X.197, Handley Page HP.115, Slingsby Sailplanes T.48, Supermarine Type 573, Miles M.110 | |
| ER.197D | 1959 | Powered research aircraft for low speed handling of narrow delta wings. | Handley Page HP.115 | |
| UB.198 | 1959 | Nuclear armed air-to surface missile for V-bombers | Avro Blue Steel | |
| D.199D&P | Proposed conversion of English Electric Canberra B2 to U.14 pilotless drones. Unbuilt. | - | ||
| UB.200D | OR.1159 | Long range nuclear armed guided bomb. Ramjet powered derivative of Blue Steel missile. Cancelled December 1959. | [Blue Steel (missile)|Avro Blue Steel Phase 2] | |
| H.201 | 1960 | Version of Saunders-Roe P.531 for Army Air Corps | Westland Scout AH.1 | |
| D.202D&P | 1959 | Pilotless target drone | GAF Jindivik | |
| C.203 | ASR.371 | 1959 | Long-range strategic transport | Avro Type 756, Hawker P.1131, Handley Page HP.111, Short Belfast, Vickers VC10 Military Freighter |
| ER.204D | 1960 | Experimental VTOL aircraft using Bristol Pegasus | Hawker P.1127 | |
| T.205D&P | 1960 | Two seat trainer version of English Electric Lightning | English Electric Lightning T.5 | |
| ER.206 | OR.346 | 1959 | Variable-sweep wing research aircraft, closely aligned with OR.346 for a strike aircraft for RAF and RN. Not developed. | BAC/Type 588, Vickers ER.206, Vickers Type 583 |
| CC.207D&6 | OR.342 | 1960 | Purchase of de Havilland Canada Beaver for Army Air Corps | de Havilland Canada Beaver AL.1 |
| D.208D&P | 1960 | Developed version of Jindivik target drone | GAF Jindivik 102 | |
| D.209D&P | 1960 | Conversion of Gloster Meteor F.8 to pilotless target drones by Flight Refuelling Ltd. Similar to U.16 | Gloster Meteor U.21 | |
| RH.210 | 1960 | Enlarged, Rolls-Royce Tyne-powered, military transport version of Fairey Rotodyne gyroplane. | Fairey Rotodyne Z | |
| HAS.211T | 1960 | Initial tender for improved version of Westland Wessex for Royal Navy. Specification developed fully in HAS.227.D&P. | Westland Wessex HAS.3 | |
| C.212D&P | 1960 | de Havilland Comet Mk.4 transport for RAF | de Havilland Comet C.4 | |
| C.213D&P | 1961 | Vickers VC10 transport for RAF | Vickers VC10 C.1 | |
| GAR.214D | OR.345 | 1960 | Tactical ground attack and reconnaissance aircraft. Specification issued to Hawker Siddeley. Abandoned by 1963 | |
| UT.215D&P | 1962 | Training round for Blue Steel without engine or warhead, to be carried by V-bombers for training flights. Unbuilt. | - | |
| HAS.216 | 1961 | Small shipboard anti-submarine helicopter. Production version of Saro P.531 | Westland Wasp | |
| ER.217 | Ground effect research machine to be built by Folland Aircraft. Not progressed. | |||
| MR.218D | OR.350 | Maritime patrol aircraft for RAF. Avro Shackleton replacement. Superseded by MR.281/OR.357. | ||
| C.219D&P | 1963 | VIP transport aircraft – modified Hawker Siddeley HS.748 airliner | Hawker Siddeley Andover | |
| OR.303 | 195? | Lightweight fighter to intercept Soviet Tupolev Tu-4 bombers | Folland Midge | |
| FGA.236 | GOR.345 | 195? | V/STOL combat aircraft version of Hawker P.1127 – Harrier development | Hawker Siddeley Kestrel FGA.1 |
| OR.350 | 18 July 1960 | Maritime patrol aircraft to enter service by 1968 | Nimrod MR.1 | |
| OR.351 | 1960 | V/STOL freighter | English Electric P.36 | |
| OR.356 | 19?? | Supersonic V/STOL – Spec. SR.250 | Hawker Siddeley P.1154; later cancelled | |
| OR.357 | 19?? | Maritime reconnaissance aircraft – led to Nimrod | Hawker Siddeley Nimrod | |
| OR.362 | 19?? | Supersonic trainer aircraft – led to Jaguar | SEPECAT Jaguar | |
| ASR.365 | 196? | Helicopter – Tactical Support | Westland Puma | |
| ASR.367 | 196? | Bomber – Vulcan B.2 – see also B.35/46 | Avro Vulcan B.2 | |
| ASR.368 | 196? | Bomber – Victor B.2 – see also B.35/46 | Handley Page Victor B.2 | |
| ASR.372 | 196? | Trainer version of Lightning – Lightning T.5 | English Electric Lightning T.5 | |
| ASR.373 | 196? | VIP Transport aircraft – Andover CC.2 | Hawker Siddeley Andover CC.2 | |
| ASR.376 | 196? | Tanker aircraft | Handley Page Victor B(K).1 / Handley Page Victor B(K).1A | |
| C.239 | ASR.378 | 196? | Transport aircraft – VC10 | Vickers VC10 |
| ASR.381 | 196? | Interim Maritime Patrol aircraft to Spec. MR.254 – written around Atlantique | Breguet Atlantique | |
| ASR.382 | 196? | Two-seat trainer version of P.1154 for RAF – cancelled | Hawker Siddeley P.1154 | |
| ASR.384 | 196? | Harrier requirement – see also GOR.345 | Hawker Siddeley Harrier | |
| ASR.385 | 196? | Phantom for RAF | McDonnell Douglas F-4M Phantom II | |
| ASR.397 | 1970 | Basic jet trainer – BAC Jet Provost replacement | BAE Systems Hawk T.1 | |
| ASR.400 | Airborne Early Warning Aircraft | Hawker Siddeley Nimrod AEW.3 | ||
| ASR.409 | Harrier replacement | BAe/McDonnell Douglas AV-8B Harrier GR.5 | ||
| T.301 | AST.412 | Jet Provost replacement | Short Tucano T.1 | |
| GOR.2 | 1959 | VTOL Strike Reconnaissance aircraft | English Electric P.31, Gloster P.505 |
Naval requirement/Aircraft, Naval Staff requirements
| Spec | Req. | Year | Type | Related aircraft |
| U.25/49 | NA.03 | Small Pilotless Target Aircraft | ||
| N.12/45 | NA.07 | Single Seat, Long Range, Naval Fighter Aircraft | Westland Wyvern TF.2 | |
| N.114T | NA.14 | 2-seat all-weather day/night fighter | ||
| N.9/47 | NA.17 | 16/09/47 | Naval Fighter Aircraft | Supermarine Type 508, 525 and 529 Scimitar prototypes |
| S.14/48 | NA.21 | 09/07/48 | Naval Version of Sikorsky S.51 Helicopter | Westland Dragonfly HR.1 |
| 19/48P | NA.27 | Production of a Naval Fighter to E.1/45 | Supermarine Attacker F.1 | |
| NA.31 | 195? | Skeeter for RN | Saunders-Roe Skeeter | |
| M.123 | NA.32 | 195? | Light carrier-borne Anti-submarine warfare aircraft to Spec. M.123 | Short Seamew |
| NA.34 | May 1952 | Hooked Swift for Carrier Trials | ||
| NA.36 | de Havilland Sea Vampire T.22 | |||
| M.148 | NA.39 | 08/02/53 | Carrier borne strike aircraft to Spec. M.148T | Armstrong Whitworth AW.168, Blackburn Buccaneer, Short PD.13 |
| NA.43 | Anti-Submarine and General Purpose helicopter | |||
| NA.47 | 195? | Mixed rocket-jet interception fighter for Royal Navy | Saunders-Roe SR.177; cancelled 1957 | |
| NSR.6451 | 19?? | V/STOL carrier borne fighter aircraft – Naval Hawker Siddeley Harrier | BAE Sea Harrier |
General Staff Requirements For Aircraft
| Spec | GSR | Year | Type | Related aircraft |
| GSR.3335 | 196? | Helicopter – Westland Scout replacement | Westland Lynx | |
| GSR.3336 | 196? | Helicopter – Bell 47G Sioux replacement | Westland Gazelle |