Aircraft camouflage



Aircraft camouflage is the use of light and color patterns applied to military aircraft for the purpose of making an aircraft more difficult to see on the ground, in the air, or to make its speed, distance or attitude difficult to determine. Camouflage is highly dependent upon environmental conditions and is primarily effective against human observers, though some electronic visual acquisition systems can also be confused. It does not hinder radar location or heat-seeking electronics although the paints used may contain substances that can.

Camouflage colours and patterns are subject to considerable experimentation and theorizing, and most countries have explicit specifications as to their application that are sufficiently unique to make it possible to determine the intended operator in many cases even when no national insignia is visible. The colours and patterns have changed over time, both as new theories were tried, and as operation requirements changed. During and after World War II, experiments using lamps ("Yehudi lights") to increase the brightness of the aircraft to match the background were trialled, and recent experiments have looked at the use of light-emitting active camouflage systems which allow the colours and patterns to be changed to match the background.

Aircraft were first camouflaged during World War I and camouflage has been widely employed in most major conflicts since then.

Camouflage has been dispensed with when air superiority was not threatened or when no significant aerial opposition was anticipated, to reduce the cost of maintaining matte camouflage finishes which add weight and drag to an aircraft, as well as requiring more frequent repainting.

Usage
Camouflage for aircraft is complicated by the fact that the appearance of the aircraft's background varies widely, depending on the location of the observer, the nature of the background and the aircraft's motion. For this reason, many military aircraft were painted to match the sky when viewed from below, and to either match the ground or break up the aircraft's outline when viewed from above.

This is known as countershading, and can be useful on aircraft such as heavy bombers that do not do much inverted flying during combat. Because of the way light hits it, patterns of dark and light will often be present on an aircraft even if it is entirely one color, which will affect the apparent size of the aircraft. Further emphasis in this direction can be made by painting an aircraft in several neutral shades with a non reflective, matte finish.

Night camouflage
Military aircraft flying at night have often been painted black, dark grey, dark green or other dark colours. This dark color has been applied to just the underside of some aircraft and to the entirety of others. In World War II, aircraft in the night sky tried to avoid being illuminated by enemy searchlights and flares, and being sighted by enemy night fighters. A matte-painted surface reflects the least light but, because of its roughness adds additional skin friction or parasitic drag which reduces aircraft speed and range. The RAF used a concoction called special night that was the epitome of this, and would rub off if brushed. A de Havilland Mosquito's top speed was reduced more than 20 mph when using special night finish.

An all-black finish often silhouettes an aircraft against the sky. To reduce this undesirable effect, numerous other colours have been substituted, including the British NIVO (used between the wars), and various greys (used in the latter part of World War II by the RAF.)

Ground camouflage
Camouflage is often used to inhibit visual acquisition from the air of an aircraft that is on or near the ground. A variety of patterns have been used to obscure aircraft outlines over specific environments. Light sand colors have been used for aircraft used over deserts, blues and greys for aircraft over the sea, and greens and browns for aircraft that are expected to operate in forested areas. This solution causes another problem: the very pattern that makes it more difficult to spot the aircraft when parked makes it stand out when moving, since the pattern provides a high degree of contrast against a stationary background. When the need to hide parked aircraft declines, so does the tendency to use such schemes. A single solid neutral colour was chosen by the United States Army Air Corps precisely because it provided a better compromise between hiding the aircraft on the ground and in the air.

A camouflaged aircraft either on the ground or flying low over the ground in bright sunlight is vulnerable to being detected from above because of its own bold, black shadow cast on the ground. This can reduce an aircraft's camouflage effectiveness at altitudes up to 3000 ft, particularly if the ground surface is light colored and homogenous.

Air camouflage
Camouflage for an aircraft that is in the air can have several purposes. Primarily, it attempts to hide the aircraft but failing that, it can disguise an aircraft's attitude or distance.

Some camouflage effects used on fighters are to paint a mock cockpit on the underside of the aircraft, and to use countershading (painting areas that would normally end up shaded a lighter tone, and vice versa). An automimicry tactic such as this can confuse an enemy pilot as to the direction the falsely painted fighter will maneuver for long enough to gain a decisive advantage.

The higher speeds of modern aircraft, and the reliance on radar and missiles to defend against them have reduced the value of visual camouflage, while increasing the value of electronic "stealth" measures. In conjunction with the design of the aircraft, modern aircraft paints may be impregnated with compounds designed to absorb electromagnetic radiation used by radar, decreasing the distance they can be detected, and to limit the emission of infrared energy used by heat seeking missiles to detect their target. Examples of this include the black schemes found on the F-117 stealth fighter and SR-71 reconnaissance aircraft which contain small graphite pellets arranged to scatter and diffuse specific wavelengths of radar waves, while the black helps disperse heat quickly.

Active camouflage


In the early years of World War II, German U-boats often escaped attack by aircraft because they spotted the aircraft while it was still far away as a black dot in the sky, no matter what camouflage colours were used. To solve this problem, in 1943 the U.S. Navy conducted secret experiments on counter-illumination under a project named "Yehudi". Sealed beam lights were mounted on the leading edge of the wing of a TBM-3D Avenger, and around its engine cowling, with the lamps facing forward. The intensity of the lamps was adjusted to match the background sky as seen from an observer in a surface ship. Aircraft with Yehudi lights were not spotted until 2 mi away under conditions where aircraft without the lights were spotted 12 mi away. Though successful, the system was not put into production because of improvements made to radar detection.

During the Vietnam War, Yehudi lights were again tried, this time mounted to an F-4 Phantom which also was given a dull blue-and-white camouflage pattern. The experiment reduced by 30% the distance at which an observer visually acquired the Phantom.

Modern experiments with the Yehudi concept involve thin fluorescent panels or thin light-emitting polymer covering much of an aircraft's surface. Computer-controlled circuitry quickly changes the light qualities of the aircraft surface to confuse human and electronic visual identification. Such systems are not yet in production.

History
The earliest military aviation was conducted with observation balloons. These were typically unreachable by ground fire, so there was little reason to make them hard to see. Not until aircraft could be effectively targeted did camouflaging them then become an issue.

World War I
Military camouflage was influenced by the rise of military aviation during World War I. With aircraft flying over the battlefield and rear areas, units vulnerable to attack needed to hide their presence.

Attempts at hiding aircraft that were parked on the ground were made during World War I by all combatants. The most common colors applied to aircraft upper surfaces were plain earth and forest tones as used by the United Kingdom, or large blotchy camouflage schemes intended to hide the aircraft near patchy foliage. Lower surfaces were either in light colors or left unpainted. The finish used was not paint, but dope which sealed the surface of the fabric while both tightening it and allowing it to flex slightly. Until later changes in formulation it was extremely flammable and required frequent maintenance to prevent it drying out and cracking and unlike camouflage finishes used later was very glossy unless in poor condition.

French World War I camouflage
The French were among the first to introduce camouflage, however it may have been a side effect from some of the materials aircraft were covered with, and some Nieuport 10 fighters were dark red-brown overall in 1915. Nieuports were used for a variety of experiments, with brown and green over a light blue being used operationally, while a small number of all light blue Nieuport 11 fighters were trialled. Early SPAD fighters followed pre-war practice and used a sand coloured dope. Between 1916 and 1917, Nieuport used aluminium dope which provided excellent camouflage against other aircraft while in the air (it dulled in service to a light grey) while also increasing the lifespan of the fabric covering. In 1917, the French Air Service finally issued an official specification for a camouflage scheme. It used dark brown, light brown (or ecru), light olive green and dark olive green, sometimes with splothes of black. This was applied to uppersurfaces only and the undersurfaces were doped in ecru. A variety of dark colours including black, dark blue and violet were trialed on night bombers. In late 1918 a single overall dark green colour applied with a precoloured fabric (rather than doped) replaced the 4/5 colour scheme and was used well into the interwar period.

German World War I camouflage


Like the French, the German air services used brown and green camouflage on its Albatros fighters however a series of friendly fire incidents resulted in a decision to replace the brown with purple. From a distance the purple worked well as a camouflage colour, while providing a distinctive identifying colour from close up. As in France, individual manufacturers applied a variety of camouflage finishes, dependent on their own interpretations of what was required. Light grey (LFG Roland C.II), patches of greens and browns (Fokker D.II) and streaky olive green finish over a turquoise base (Fokker Dr.I) were all used until 1917, when lozenge camouflage (Lozenge-Tarnung) was introduced. Unlike other preceding finishes, the irregular polygons characteristic of lozenge camouflage were printed directly on the fabric and required no coloured dopes, thus simplifying the application of fabric and repairs, often giving a more "faded", pastel-like intensity to the printed colors used. A variety of different patterns and colours were used, including special ones for naval aircraft, and for night bombers. Different sets of shades were used for upper and lower surfaces.

British World War I camouflage
During the first World War, the British Royal Flying Corps discovered that aircraft which spent much of their time outside had the fabric deteriorate from the effects of UV radiation. Experiments with a variety of pigments showed that black provided the best protection, but several other colours provided adequate protection while also having some camouflage value. The two colours chosen for use were Pigmented Cellulose Specification 10, normally known as PC.10 (brown or olive brown with at least 5 different recipes) and PC.12 (red-brown made from red iron oxide and black) which were applied over all upper surfaces, leaving only the undersides of the wings in clear doped linen (a pale cream colour). PC.12 was intended for aircraft stationed in the Middle East such as the Bristol M.1, but was also commonly used on aircraft of the Royal Naval Air Service, such as the Sopwith Triplane. RNAS aircraft could sometimes be identified as the coloured dope was not always applied to the sides of the fuselage.

Black was also used for night bombers, while a wide variety of experimential camouflages were tried out for specific roles such as trench strafing, with multiple colours. Due to the black being silhouetted against the sky, a variety of alternatives was tested in late 1917 in Orfordness Experimental Station, resulting in NIVO (NIght Varnish Orfordness) being introduced in early 1918, which was used for all external surfaces on night bombers. Between the wars, the British replaced PC.10 and PC.12 with aluminium dope but continued using NIVO until superseded by World War II colours.

British World War II camouflage
During the Munich Crisis (also known as the Sudeten Crisis), when Hitler was demanding the partition of Czechoslovakia, the Royal Air Force implemented plans to camouflage its aircraft in its Temperate Land Scheme of "Dark Earth" and "Dark Green" over "Sky", with "Light Green" and "Light Earth" on the uppersurfaces of the lower wings on biplanes. This scheme was known colloquially as Sand and Spinach when the pattern was painted on at the factory, large rubber mats serving as guides. For many types of aircraft, particularly fighters, the rubber mats were reversed for even and odd serials, named A and B patterns. From April 1939 until June 1940, during the Phony War and the Battle of France, the undersides of fighters were painted so that the port wing or whole port half of the undersides was black, and starboard undersides painted white as a recognition feature so that allied anti-aircraft gunners wouldn't fire on their own aircraft. This was abandoned during the Battle of Britain, when the undersides of aircraft reverted to "Sky" for fighters and light day bombers, and black for night bombers.

The British Fleet Air Arm continued to use the peacetime silver doped finishes as they were believed to offer good camouflage against the sky but when it was realised that it made them stand out when parked on the ground or sitting on the water and a number of experiments were conducted. Initially the FAA used "Medium Sea Grey" and "Dark Green" over "Sky Grey" but after the Norwegian Campaign switched to the RAF Temperate Sea Scheme of "Extra Dark Sea Grey" and "Dark Slate Grey" over "Sky". This scheme was nicknamed Sludge and Slime. Multi-engined aircraft built as transports normally used the Temperate Sea Scheme.

Some aircraft in the Mediterranean and far east were finished in the Tropical Sea Scheme of "Dark Mediterranean Blue" and "Extra Dark Sea Green" with "Sky Blue", "Sky Grey" or silver undersides, and with the tops of the lower wings on biplanes a lighter shade of the main colours. Heavy bombers kept the "Dark Earth" and "Dark Green" for the topsides throughout the war, but had their undersides painted in a special black paint called "Night", and from August 1940 night fighters were painted overall in the same colour. From December 1940, aircraft operating in desert environments were painted "Mid Stone" and "Dark Earth" with "Azure Blue" undersides.

After the Battle of Britain, the RAF was able to shift from the defensive to the offensive. While the browns and greens worked for aircraft on the ground, they were less than ideal for offensive patrols over France and Germany and the "Dark Earth" was replaced by "Ocean Grey" and "Sky" with "Sea Grey" from September 1941 onwards. At the same time, the reverse A and B patterns were discontinued, all aircraft now being A-pattern only. In July 1942 the scheme used for night fighters was changed so that the topsides were "Dark Green" and "Sea Grey Medium" and the undersides were also "Sea Grey Medium". This was done as night fighters were easily silhouetted against the sky if painted black and the grey was harder to see. Intruder aircraft continued to use "Night" undersides but with "Dark Green" and "Sea Grey Medium" topsides. Also in July 1942, the undersides and sides of Coastal Command aircraft (aircraft used for Anti-submarine patrols) were changed to white. In October 1944 the colours of Coastal Command aircraft were simplified to "Extra Dark Sea Grey" over white. A variety of different colours were used on Photo Reconnaissance aircraft, based on local unit preferences rather than official orders. Aircraft supplied by the U.S. to the RAF and FAA were rarely able to match the exact colours but used commercially available colours that were close. The patterns on all British aircraft were closely regulated, with the divisions between colours being set out in official orders.

German World War II camouflage


The basic German camouflage during most of the war was based on a Hellblau (light blue) undersurface and a two tone splinter pattern of various greens for the upper surfaces. In the first year of the war, the top colours were Dunkelgrün (dark green) and Schwarzgrün (black-green), later lighter and more greyish colours were used for fighters, though bombers mostly maintained the dark green/black green camouflage. The side of the fuselage on fighters and some light bombers often had splotches sprayed on, making the transition from the upper to the lower surface less obvious. Splotching was sometimes also applied to the remaining upper surfaces as well. The undersides of night bombers and night fighters were often painted black. During Operation Barbarossa the Luftwaffe adopted a white water-based overpaint for the upper surfaces. The paint did however add to weight and particularly drag, and the use of the winter overpaint for aircraft was restricted or dropped altogether during the remainder of the war.

Additional variants existed, particularly during the early and late part of the war.

A special pattern was devised for the Mediterranean front, consisting of a brown Sandgelb (sand yellow) that often faded to tan, with or without olive Olivengrün splotches and painted or sprayed on. Later in the war, as Germany lost air supremacy, camouflage of aeroplanes on the ground became increasingly important. Late war fighters received a two tone scheme not dissimilar to the early war Sand and Spinach of the British planes, with Dunkelbraun (dark brown) and Hellgrün (light green). and the Luftwaffe Problems with identifying friendly aircraft resulted in a variety of supplementary identification colors being used throughout the war, including yellow Home Defense markings and the case of the Papagei Staffel (Parrot squadron) tasked with escorting Me 262 jet fighters when landing, red lower surfaces with white lines.

U.S. Army Air Forces World War II aircraft camouflage
Some United States Army Air Forces aircraft used a variation of the British camouflage schemes (mostly on aircraft originally built to RAF orders) but most USAAF aircraft did not use multiple shades on the top side of the aircraft. Instead, most were camouflaged in olive drab (FS.34087) above and neutral gray (FS.36173) below, though some had the edges of flying surfaces painted in medium green (FS.34092). In the later stages of the war camouflage was often dispensed with, leaving aircraft in a natural metal finish.

U.S. Navy World War II aircraft camouflage
The U.S. Navy used a variety of schemes throughout the war. From December 30, 1940 for Patrol aircraft and from February 26, 1941 for land based amphibians, topsides were to be painted in M-485 Blue Gray and undersides in M-495 Light Gray. From August 20, 1941 all ship's aircraft (attached to Carriers or Battleships) and from December 26, 1941 all land based Aircraft were to have topsides (and the undersides of folding wings if undersides visible from above) painted in No. 12 Blue Grey while the remainder of the undersides were to be in No. 10 Light Grey.

From January 5, 1943 all aircraft were to be painted in a four colour scheme consisting of ANA 606 Semi Gloss Sea Blue upper surfaces with ANA 607 Non Specular Sea Blue on the upper surface of the wing leading edges, ANA 608 Non Specular Intermediate Blue on the vertical tail, a graded tone close to FS-35189 Blue Grey (mixed from ANA 601 & ANA 607) on the fuselage sides, and ANA 601 Non Specular Insignia White on the undersides. The portions of the wings visible from above when folded were painted in the graded tone used on the sides. From July 1943, aircraft used in an anti-submarine role were given a special scheme of ANA 621 Non Specular Dark Gull Grey over ANA 601 Non Specular Insignia White and ANA 511 Glossy Insignia White. From June 26, 1944, all Navy carrier aircraft were to be repainted in ANA 623 Glossy Sea Blue. This was extended to cover other types of aircraft. In most cases, it took time from when the order was made, before the aircraft were repainted.

Imperial Japanese Naval Air Service World War II aircraft camouflage
At the time of the Attack on Pearl Harbor, Japanese navy fighters and some bombers were painted overall in a very pale grey or grey green though some aircraft were already being painted in the standard dark green over light grey that would be used for most of the rest of the war. In some instances splotches were added over the standard scheme to break up the shape. Aircraft that had been in service earlier often had a multi-colour scheme in shades of brown and green. Cowlings for radial engines were normally painted black, which was also used for aircraft that operated at night. Aircraft used for training were painted orange, often with green upper surfaces later in the war. Each manufacturer used their own colors.

Imperial Japanese Army Air Forces World War II aircraft camouflage
Early in the war, Japanese Army aircraft were often light grey overall, though this was gradually replaced with various shades of green and brown, either as a solid colour or mottled. Undersides were normally left unfinished. Not all aircraft were camouflaged, with many aircraft retaining a natural metal finish even late in the war. Reconnaissance aircraft were painted light grey or light grey green and aircraft operating at night were painted black (often overall). Like the Japanese Navy, many pre-war aircraft remained in use with earlier 3 colour schemes and a lot of local variations existed.

Allied D-Day invasion markings
In the latter stages of World War II the necessity of recognizing aircraft as friendly or hostile in an increasingly crowded sky almost negated the use of camouflage for daytime operations, with Allied forces introducing invasion stripes for D-Day and the invasion of Normandy.

Cold War
During the Cold War, glossy, all-white finishes were used on nuclear bombers as protection from nuclear flash, except some RAF squadrons which used green/grey RAF camo on their V-bombers. Camouflage was reintroduced during the Vietnam war by the USAF for combat aircraft, initially limited to black undersides for night bombers, until the South East Asia (SEA) Scheme was introduced in 1966 consisting of light green, dark green and tan over either grey or black. Interceptors were painted overall light grey (aircraft grey) as were close support aircraft.

In the early 1970s two tone grey schemes began to replace the SEA and overall grey interceptor schemes while in 1978, the European 1 scheme of dark green, dark grey and medium green were introduced. In 1981 the F-117 Stealth fighter reintroduced an overall black scheme. The US Navy replaced the World War II sea blue scheme with light grey over white in February 1955 which was used until the late 1970s when overall grey on grey schemes began to be used.

In the 1970s, heat-seeking missiles were developed that had a range greater than the visual acuity of pilots. Aircraft camouflage now had two major threats that it was not able to fully defeat — radar and infrared detection.