The air forces of the United Kingdom – the Royal Navy's Fleet Air Arm, the Army's Army Air Corps and the Royal Air Force use a roundel, a circular identification mark, painted on aircraft to identify them to other aircraft and ground forces. In one form or another, it has been used on British military aircraft from 1915 to the present.
Background
When the First World War started in 1914, it was the habit of ground troops to fire on all aircraft, friend or foe, so that the need for some form of identification mark became evident.Robertson 1967, p 89 At first the Union Flag was painted under the wings and on the sides of the fuselage. It soon became obvious that at a distance the St George's Cross of the Union Flag was likely to be confused with the Iron Cross that was already being used to identify German aircraft. After the use of a Union Flag inside a shield was tried it was decided to follow the lead of the French who used a tricolour cockade (a roundel of red and white with a blue centre). The British reversed the colours and it became the standard marking on Royal Flying Corps aircraft from 11 December 1914, although it was well into 1915 before the new marking was used with complete consistency. The official order stated:
The Royal Naval Air Service specified in A.I.D. SK. No. A78 a five-foot red ring with a white centre and a thin white outline on the lower surfaces of the lower wings at mid span, from October 1914 until it was decided to standardise on the RFC roundel for all British military aircraft in June 1915. With the same roundel being carried by RFC and RNAS aircraft, the use of the Union Jack was discontinued. The Royal Flying Corps and its successor the Royal Air Force have employed numerous versions of the roundel since then.
By 1917, a thin white outline was usually added to the roundel, to make the blue of the outer circle easier to distinguish from the dark PC.10 and PC.12 protective dope. On squadrons operating at night there was not the same need to make the marking more conspicuous, indeed it became customary to overpaint the white ring of the roundel itself, either in the camouflage finish of the aircraft as a whole, or in red. By the end of the war this had become standardised as the so-called "night roundel" of blue and red, which continued to be used on the dark NIVO green camouflage of post-war night bombers. Most RAF aircraft now had a silver finish (either bare metal or aluminium dope) so that the national markings were conspicuous enough without outlining. During the late 1930s RAF and Fleet Air Arm (FAA) aircraft were once again camouflaged, and a new outline was introduced, this time trainer yellow, and the same width as the blue and white rings.
Use by other air arms Aside from the RAF, the Royal Navy's Royal Naval Air Service (First World War) and later the Fleet Air Arm as well as the air elements of the British Army all adopted the same roundels.
Many nations which had been within the British Empire and Commonwealth continued to use British roundels despite having achieved independence, including Canada, Australia, New Zealand, and India until nationalism demanded unique roundels for each of those countries.
South Africa experimented with the four flag colours briefly, but then reverted to the RAF roundel but replaced the red with orange, and then the dot with a Springbok before replacing the disk with a five pointed castle.
In Canada, the Royal Canadian Air Force changed the red dot into a silver maple leaf, while the Royal Canadian Navy adopted the sugar maple leaf and both were replaced with a geometric stylized leaf.
Australia changed the red dot to a kangaroo (both standing and running were proposed before the running variant won out) and New Zealand experimented with gold, green and white ferns inset in the red dot before settling on a red kiwi.
India briefly replaced the SEAC roundel (blue on blue) with a blue and white Ashoka Chakra, before adopting an orange, white and green roundel on similar lines.Flags of the World: Indian Air Force Flags
Southern Rhodesia, the Federation of Rhodesia and Nyasaland and Rhodesia used variations on the British roundel featuring assegais before adopting a green ring with a lion and tusk on a white centre in 1970.
Roundel history The use of letters (A, B, C, D) to denote different versions of roundels does not come from official documents, but rather from attempts by historians in the 1950s to catalogue the various roundels being used. Official documents instead provided dimensions in inches. Since most sources now use this nomenclature it has been included here. Ratio1:3:5Type AOn all light-coloured surfaces 1915 to late 1929, and on dark surfaces with a 2-inch white border (similar to later type A2) on camouflaged surfaces 1915–1919. Colours used were to VB and VR specifications (with a number from 1 to 5 defining exactly which spec), colours did not change much; however, early versions were prone to fading. Prior to the introduction of the Type B night roundel, aircraft used on night operations had the white overpainted with the prevailing camouflage colour, usually PC.10 or black. Due to the effect of orthochromatic film – the most widely available film during World War I and onwards through the early World War II years – rendering the blue very pale and the red very dark in photographs, historians in the 1950s and 1960s incorrectly believed a white ring roundel had been used on home defence aircraft.Ratio1:3:5Type AUsed after late 1929 when colours were increased in saturation until replaced by Type B during summer 1938. Official names of colours changed to "identification red" and "identification blue". As on the earlier Type A roundel, a white border was sometimes used, mainly on flying boats and some prototypes from 1923 to 1937 even when the aircraft was doped silver.Ratio1:3:5Type ADuller colours (referred to as "identification red (dull)" and "identification blue (dull)" in official orders), used with Type A.1 during WWII but on light surfaces, primarily under the wings of fighters until replaced by Type C in June 1942ID red (dull) referred in some sources as "brick red" which is confirmed by colour photos.Ratio1:3:5:7Type A.1On all camouflaged surfaces 1937 – March 1939 (e.g.: Supermarine Spitfire); on fuselage sides 1939 to replacement by type C.1, July 1942. On some night bombers the white was overpainted with black to reduce visibility. Also used with bright pre-war colours, especially on trainers. The chrome yellow outermost ring on this roundel variation was usually picked up by orthochromatic film in photos as a shade of dark grey, nearly as dark as the central red circle would be. Also used as ground vehicle markings in the UK, Middle East, North Africa and Italy from January 1942 to mid-1943 as air recognition signs.Ratioapprox.1:3:5:6Type A.2Outer yellow ring is thicker than used during WWI. Alternative to A.1 on some aircraft 1940 – 1942, including the Grumman Martlet as received from the factory, indicating that it was likely official despite the lack of orders describing it. Also used as ground vehicle markings in the UK, Middle East, North Africa and Italy from January 1942 to mid-1943 as air recognition signs.Ratio2:5Type BOn some night flying aircraft, especially heavy bombers, 1918 – 1919. (Known at this time as the "night roundel"). On all surfaces of NIVO-coloured night bombers from 1923 until NIVO phased out; Used on camouflaged aircraft in all positions from Summer 1938 until superseded by Type A.1 roundels. Used on upper surfaces of many aircraft until 1947. On fuselage sides and upper wings of overall PRU blue photo-reconnaissance aircraft 1940 – 1944 (e.g.: photo-reconnaissance Spitfires) and aircraft with "high altitude" camouflage (e.g.: de Havilland Hornet) 1944 – 1947.Colours were VNR.5 & VNB.6 in 1927, identification red and blue (dull) (usually) after 1929Ratio2:5:8Type B.1On some aircraft March – December 1939. Used on fuselage sides of some night-flying aircraft (bombers, e.g. Vickers Wellington; night fighters, e.g., Boulton Paul Defiant) late 1940 – mid-1942. Often type B with additional yellow ring (proportions do not match Type A).Ratio3:4:8Type COn light surfaces July 1942 – 1947; not used on upper surfaces 1942–1945.Ratio3:4:8:9Type C.1On dark surfaces except upper surfaces July 1942 – January 1945; upper wings and fuselage sides of all Second Tactical Air Force (2 TAF) bombers and photo-reconnaissance Spitfires, January 1945 to early 1947. Upper and lower wings and fuselage sides of 2 TAF fighters (e.g.: Hawker Tempest) January 1945 to early 1947.Ratio4:8:9(SEAC)Used by units under South East Asia Command and in the China Burma India (CBI) theatre in 1942. Red removed to avoid confusion with the Japanese hinomaru, but retained on fin flash. Not used for very long before being replaced by light blue and dark blue roundel.
A blue/white roundel, sometimes with US-style white bars, was also used on Fleet Air Arm aircraft Blue/white roundels were also used by the Royal Australian Air Force (RAAF), which simply over-painted the red dot in white, regardless of previous proportions.Ratio2:5(SEAC)Used by units under South East Asia Command and in the CBI theatre mid-1942 – 1946. Red removed to avoid confusion with Japanese hinomaru. Initially red was overpainted with white but this compromised the camouflage and the normal roundel blue was mixed 50:50 with white. Many aircraft in the CBI theatre used roundels and fin flashes of approximately half the normal dimensions.Ratio1:2:3Type DOn all surfaces from June 1947 to this day, with similar proportions to the current roundel of the French Armee de l'Air. Colours reverted to Bright Identification colours but were matched to a new British Standard colour chart so colours were different from prewar bright colours. Note the different proportions from the Type A. The Type D was first used on ground equipment, including jeeps, and with a yellow outline on rescue launches.Ratio1:2:3Type D paleA pale 'faded' version of the Type D. This was sometimes used when applied over anti-flash white. An intermediate (less faded) pale version was applied to some Vickers Valiants prior to the introduction of the definitive Type D 'faded' shading.Ratio1:2Low-visibilityLow-visibility roundel used on camouflaged aircraft since the 1970s (different proportions from Type B).Ratio1:2Low-visibilityLow-visibility roundel used in conjunction with air superiority grey schemes since the 1980s. Colours are known as "salmon pink" and "baby blue".Ratio1:2Low-visibilityLow-visibility roundel used on the Lockheed Martin F-35 Lightning II, with the centre being the same grey as the airframe. Unlike previous roundels, they are created in the manufacturing process of the airframe rather than painted on.
Roundel sizes Pre-war Up until mid-1938, roundel sizes tended to vary widely, depending on the type of aircraft; the exception to the use of type A roundels for all aircraft was seen on the overall NIVO (a dark grey-green finish with a sheen) painted night bombers (e.g., Handley Page Heyfords) which used type B roundels. Roundels used on aircraft painted in NIVO were duller than the normal colours. The size of the roundel was generally determined by the space available at the specified location, with a space of several inches around the edges. Some aircraft – primarily seaplanes, had a white outline around the fuselage roundel, even on silver doped finishes however this application was inconsistent so was probably not official. From 1929, the RAF switched to a new system of colour specifications, discarding the one used since the First World War, and as a result, the colour used for insignia changed, however the changeover period appears to have extended until at least 1932 for new production, and the old colours were not overpainted, but only gradually phased out as aircraft needed to be repainted.