British military aircraft designation systems

Since the end of the First World War, aircraft types in British military service have generally been known by a "type name" assigned by their manufacturer, or (for various imported types) bestowed upon them by the first military service to bring them into service. Individual variants are recognised by mark numbers. This is in contrast to the systems such as that used in the United States, where an aircraft type is primarily identified by an alphanumeric designation.

Pre-1918
From about 1910, the largest single designer of aircraft for the British Army's Royal Flying Corps was the Royal Aircraft Factory, Farnborough (although most were built elsewhere). The Royal Aircraft Factory designated its types according to several categories, which were given the following prefixes:

R.T. & T.E. were also used for strictly one off prototypes.
 * B.E.: Blériot Experimental (tractor configurations) (e.g. B.E.2)
 * F.E.: Farman Experimental (pusher configurations) (e.g. F.E.2)
 * R.E.: Reconnaissance Experimental (e.g. R.E.8)
 * S.E.: Scouting Experimental (e.g. S.E.5), up to 1913 S.E. had the meaning of Santos Experimental (Canard or tail-first layout)
 * C.E.: Coastal Experimental (e.g. Royal Aircraft Factory C.E.1 - prototype only)
 * N.E.: Night Experimental (e.g. Royal Aircraft Factory N.E.1 - prototype only)

The Admiralty chose to have private industry design and build its aircraft and frequently referred to designs by the serial of the first aircraft of that type to be accepted for service, although not always. The Army also bought industry-designed aircraft, especially when the Royal Aircraft Factory was unable to keep abreast of demand but no designation system was introduced during the war that covered more than the products of a single manufacturer.

Specification numbers
From 1920 to 1949, most aircraft had an associated Air Ministry Specification number. Prototype aircraft would be produced under contract and would be referred to as by Manufacturer Name and Specification Number. If accepted they would get a service name. For example, the Fairey 6/22; this being the 6th specification issued in the year 1922 that was accepted as the Fairey Flycatcher. Later, a preceding letter was added to the Specification Number to identify the type of aircraft; e.g. the Bristol B.28/35, a bomber aircraft, the 28th specification of the year 1935, which would become the Bristol Blenheim.

Naming
The names of aircraft would be suggested by the Air Ministry or Admiralty and agreed with the manufacturer when placing an order. Names generally followed one or a number of patterns;


 * Alliteration was particularly common; e.g. aircraft from Vickers-Armstrongs were given names starting with V, Hawker Aircraft, names starting with H, etc. This began directly during the First World War. Aircraft manufacturers were given an initial pairing of letters to use in the naming of their aircraft: eg Boulton Paul Ltd were given "Bo". From this and the requirement to use the names of birds or insect for fighter aircraft, their first inhouse fighter design was the Boulton Paul Bobolink. For bombers the adittional requirement was a placename, hence the Boulton Paul Bourges; and its contemporaries - the Airco Amiens and Vickers Vimy (Bourges, Amiens and Vimy all being in France.)


 * A trend might be followed by a manufacturer - Hawker Hurricane, Typhoon, Tempest


 * Heavy bombers received the names of cities and towns - Short Stirling, Avro Lancaster, Handley Page Halifax


 * Flying boats were given the names of coastal towns - Saro Lerwick, Supermarine Stranraer, Short Sunderland


 * Land-based maritime patrol aircraft were given names with nautical exploration associations - Avro Anson (George Anson, 1st Baron Anson), Lockheed Hudson (Henry Hudson), Avro Shackleton (Ernest Shackleton), Bristol Beaufort (Francis Beaufort).


 * Aircraft for army co-operation and liaison were given names associated with mythological or legendary leaders; e.g. Westland Lysander, Airspeed Horsa, General Aircraft Hamilcar, Slingsby Hengist


 * American aircraft, whether purchased directly or sourced under Lend-Lease, were given American-themed names following established patterns, e.g. the Martin Baltimore, Consolidated Catalina. The American services were not generally in the habit of giving aircraft names, and many British-chosen names would later be adopted; e.g. the P-51 Mustang began life as the North American Mustang Mk.I with the RAF.


 * Naval versions of aircraft not originally ordered for the Fleet Air Arm were given the prefix "Sea" - Sea Hurricane, Seafire (in the case of the Supermarine Spitfire), Sea Venom. Sometimes a named RAF version of an aircraft would be cancelled with the naval version entering service without a corresponding land-based name, e.g., Hawker Sea Fury, de Havilland Sea Vixen.


 * Naval aircraft ordered as such would have names with a nautical theme - e.g. Supermarine Walrus, Blackburn Skua, Fairey Gannet. Torpedo bombers would be given 'fish' names, e.g., Blackburn Shark, Fairey Swordfish, Fairey Barracuda.


 * Training aircraft would be given names related to academia, universities, etc. - Oxford, Harvard, Balliol.


 * With the introduction of jet-engined, swept wing bombers armed with nuclear weapons, these aircraft were given names beginning with "V": the V Bombers - Vickers Valiant, Avro Vulcan and Handley Page Victor.


 * Where civilian aircraft types have been taken into service, their existing names or alphanumeric designations have often been retained, e.g. the Vickers VC-10 or Lockheed Tristar.

Mark numbers
Starting in the interwar period, variants of each operational type were usually indicated by a mark number, a Roman numeral added to the type name, usually preceded by "Mark" or "Mk." (e.g. Hawker Fury Mk. I). Mark numbers were allocated sequentially to each new variant, the new Mark number signifying a 'major' change such as a new engine-type. Sometimes an alphabetic suffix was added to the mark number to indicate a minor change (e.g. Bristol Bulldog Mk. IIA). Occasionally, this letter indicated a change in role, e.g. the Bristol Blenheim Mk.I bomber was adapted to the Blenheim Mk.IF long-range fighter.

During the Second World War, as aircraft ordered for one purpose became adapted to a multitude of roles, mark numbers became prefixed with letters to indicate the role of that variant. Aircraft of the same mark that were adapted for different purpose would then be differentiated by the prefix. For instance the Boulton Paul Defiant Mk.I was adapted to a night fighter, the Defiant NF Mk.II, some of which were later converted to target tugs as the '''Defiant TT Mk. II'''. Where there was a Sea- variant, this would have its own series of mark numbers (e.g. the Seafire Mk.I was derived form the Spitfire Mk.V).

Series numbers
Occasionally other 'minor' but nonetheless important changes might be denoted by Series numbers, preceded by "Series" or "Srs." ( e.g. de Havilland Mosquito B Mk.IV Srs. I / B Mk.IV Srs.II). The series number denoted a revision during the production run of a particular Mark. This again could then have an additional letter-suffix (e.g. the Handley Page Halifax Mk. II Srs IA).

Post-1948
In 1948, Arabic numerals replaced Roman numerals. This system has continued largely unchanged to this day with the addition of more prefixes as new roles have arisen. With this change, the Sea- variants were allocated their own range within one common series for all variants (e.g. the Hawker Fury Mk.I was followed by the Sea Fury F.10, Sea Fury FB.11 etc. The use of the "Mark" or "Mk." has gradually been dropped from use.

For example, the first Lockheed Hercules variant in RAF service was the Hercules C.1 ("Cargo, Mark 1"). A single example was adapted for weather monitoring purposes and became the Hercules W.2. The stretched variant became the Hercules C.3. With aircraft with a long service life, as their function changes over time, the designation letters and sometimes the mark digit will change to reflect this.

The prefixed mark number can be presented in three different styles - for example:


 * Hercules C Mark 3 - very rarely used
 * Hercules C Mk 3 - official style
 * Hercules C3 - common abbreviated style

A full stop has generally been used to break the number from the prefix, eg. '''C. Mk. 3 or C.3''', a practice that has officially discontinued recently for current in-service types.

Export variants of British military aircraft are usually allocated mark numbers (sometimes without a role prefix) from a higher range of numbers, usually starting at Mark 50. A converse convention was adopted for the Canadian-designed de Havilland Canada DHC-1 Chipmunk, where the sole British service variant was designated Chipmunk T.10.

Role prefixes
Role prefixes used at various times comprise: