Concealment, Illusion and Manifestation 20 November 2014 By Julian Hale : Cross & Cockade Curator in First World War From the earliest days, it was found necessary to treat an aeroplane’s fabric to tauten it, to make it water-resistant and to provide a smooth airflow. In 1911, German companies found that cellulose acetate fulfilled these criteria. The popularity of this spread quickly and by 1914, almost all aircraft were finished in such a way. The chemical was more commonly referred to as “dope” and was virtually transparent, meaning treated surfaces showed fabric in its natural colour, a pale yellow brown. It was in this guise that the first British aircraft went to war in 1914. However, the rigours of service use revealed that dope was likely to deteriorate over time and it was found necessary to add a protective coat of varnish, either linseed oil-resin varnish or, more effectively, tang oil-resin varnish. However, ultraviolet light still penetrated the varnish and the Royal Aircraft Factory set about experimenting with a variety of protective finishes. These were prefixed with the letters PC, (Protective Covering), and in time, PC10, a dark green varnish, was chosen. During 1916, PC10 was gradually introduced and by the time of the Battle of the Somme, most British aircraft were wearing the new scheme. Aircraft under-surfaces remained clear-doped and varnished. An added advantage was that dark green provided good concealment against the ground when viewed from above. PC10 was to remain the standard colour for British aircraft, operating on the Western Front, for the rest of the war. However, thought was given to ways of better concealing aircraft for an array of different tasks. Some squadrons and pilots chose to apply their own, “unofficial”, camouflage schemes to their aircraft. One famous example is the S.E5a flown by Major Roderic Dallas of 40 Squadron during 1918. However, official schemes were designed and these are included below. During 1917, two Airco D.H.4s were prepared for a high-altitude reconnaissance sortie over the Kiel Canal. Both aircraft were fitted with extra fuel capacity and finished in a special low-visibility scheme, described as “matte-doped sky blue and buff.” The national markings were subdued, with the white areas over-painted with the buff colour. It should be noted that the two schemes were not identical in pattern. However, the operation was cancelled and the aircraft ended their days, still wearing their special schemes, in the UK. During 1918, an attack by torpedo aircraft was planned on the German High Seas Fleet while it lay at anchor. The aircraft selected for this task was the Sopwith Cuckoo. It was envisaged that the attack would be made at, or just after, dawn and a new, low-visibility, camouflage scheme was devised. Photographs show that a number of Cuckoos were finished in this scheme, an overall matte light sea grey. The blue areas of the national markings were replaced with the same shade of grey, leaving only a thin blue outline to the roundels. Perhaps most famous is the scheme applied to the Sopwith Salamander, an aircraft designed to be a dedicated “trench strafing” fighter. Following the enormous losses suffered by the Sopwith Camel squadron while engaged on ground attack duties during 1918, the aircraft was not only fitted with armour protection for the pilot but a new camouflage scheme was formulated as well. It was quickly accepted that merging an aircraft completely with the terrain over which it was flying was impossible and attention was given to making its identification and retention in view more difficult. Exhaustive trials at Orfordness, as well as experience at the Front, showed that it was the shadow of the upper wing upon the lower which rendered biplanes conspicuous, especially on sunny days. Accordingly, the Salamander’s lower wing was finished in a lighter tone than the upper. Dark purple-earth and green patches were applied to the upper wing in order to break up the shape and light earth-brown covered much of the lower wing. The fuselage sides were finished a light grey-green. These patches of colour were separated by black lines. The red and blue areas of the upper surface roundels were darkened and the white areas replaced with light grey-green. Meanwhile, the lower surface roundels were made as clear as possible to nullify the chances of “friendly fire.” However, only a small number of Salamanders were finished with this complex scheme and the aircraft arrived too late to see operational service. In addition, Orfordness was engaged upon the art of illusion. Experiments were made with the upper wings of Sopwith Camels, two of which are shown below. The idea was to provide a false perspective to an attacking enemy pilot, off-setting his aiming-point from the vulnerable centre-section. It may be noted that the upper wing roundels on the Salamander were placed asymmetrically and were different sizes. Another attempt at illusion can be seen in the third photograph, where it was presumably intended that an enemy pilot would be deceived into giving too little “lead” when aiming. The spiral pattern on the undercarriage wheel covers would be spun by the addition of vanes, causing the wheels to spin in different directions at every turn of the aircraft and, perhaps, spoiling an enemy pilot’s aim. Although this idea went untried in combat, (as far as is known), it should be added that Luftwaffe fighters sported black spirals on their white spinners during the Second World War, in an effort to mislead Allied air gunners while making head-on attacks. It was rapidly discovered that aircraft flying at night were vulnerable to the glare of searchlights. Some unofficial experimentation was done and, paradoxically, it quickly emerged that black was not the best shade for concealing an aircraft. The night-fighters of 50 Squadron, RFC, were given all-black finish in 1916, while the F.E2b/d night-bomber squadron in 1917 and 1918 preferred lampblack mixed with varnish. By 1917, it was felt that an official investigation, by the RFC station at Orfordness, into the most suitable colour to be used, was necessary. In January 1918, a report was produced which concluded that: “…over land and sea…a black or PC10 machine is seen as a black silhouette...the suggested colour…Nivo…appears to strike the mean, and for general night work we consider provides a camouflage which it would be difficult to improve on.” Black aircraft could not reflect light, whereas Nivo, (NIght Varnish Orfordness), reflected light in approximately the same power as both land and sea. After much trial work had been undertaken on verifying the durability of the new varnish, Nivo was approved in the autumn of 1918. However, the war ended before any aircraft in the new scheme actually flew in action. In the same report, Orfordness drew attention to the paradox of applying roundels with white circles to night-flying aircraft. In September 1916, in an effort to render identification of night-fighters easier, the following order had been circulated to the RFC’s Home Defence squadrons: “The attention of all concerned is directed to the following distinctive marking, which it has been decided shall be adopted for black-winged night flying aeroplanes: on top and bottom wings [a] white circle the same size as the blue circle used in the marking of day machines.” However, the report made by Orfordness in January 1918 unsurprisingly recommended that the white area in a roundel should be obliterated by extending the blue and red portions of the roundel. On 1 November 1918, this recommendation, which specifically included the order that the narrow outer white circle be likewise obliterated, was confirmed and enforced. By complete contrast, some flying boats of the RNAS (Royal Naval Air Service), and later the RAF, were finished in high-visibility schemes. Engine unreliability caused many to make forced landings in the North Sea and a high-visibility colour scheme improved the likelihood of rescue. As far as is known, only the boats based at Felixstowe and Great Yarmouth were finished in this way. The First World War in the Air exhibition is supported by BAE Systems and the Heritage Lottery Fund.