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Anaircraft canopy is the transparent enclosure over thecockpit of some types ofaircraft. An aircraft canopy provides a controlled and sometimespressurized environment for the aircraft's occupants, and allows for a greater field of view over a traditional flight deck. A canopy's shape is a compromise designed to minimizeaerodynamic drag, while maximizing visibility forpilots and other crewmembers.
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Very early aircraft had no canopies. The pilots were exposed to the wind and weather, although most flying was done in good weather. ThroughWorld War I most aircraft had no canopy, although they often had a small windshield to deflect theprop wash and wind from hitting the pilot in the face. In the 1920s and 1930s, the increasing speed and altitude of airplanes necessitated a fully enclosed cockpit and canopies became more common.
Early canopies were made of numerous pieces offlat glass held in position by a frame andmuntins. The muntins reduced visibility, which was especially awkward formilitary aircraft. Also, glass canopies were much heavier thanacrylic canopies, which were first introduced shortly before theSecond World War. Many aircraft used embedded canopies that restricted visibility for the pilot, some aircraft such as theCurtiss P-40 Warhawk andNorth American F-107 used rearward visibility panels, this not only intended for peripheral vision but provided ventilation and air circulation for the cockpit. The acrylicbubble canopy was used on aircraft such as theSupermarine Spitfire andWestland Whirlwind, which gave better all-round visibility and reduced weight and other advantages over the embedded canopy. It is still being used on mostfighter aircraft.
On many high-performancemilitary aircraft, the canopy is an integral part of theejection seat system. The pilot cannot be ejected from theaircraft until the canopy is no longer in the path of the ejection seat. In most ejection seat equipped aircraft, the canopy is blown upwards and rearwards byexplosive charges. Therelative wind then blows the canopy away from the ejection path. However, on some aircraft, such as theMcDonnell Douglas AV-8B Harrier II, the pilot may be forced to eject when in a hover, or when going too slow for the relative wind to move the canopy out of the path of the ejection seat. In that situation, the pilot could possibly impact the canopy when ejecting. To overcome that possibility, some aircraft have a thin cord ofplastic explosive zig-zagging across the canopy over the pilot's head. In the event of an ejection, the explosive cord is activated first, shattering the canopy. Then the ejection seat and pilot is launched through the shattered canopy.
Most modern acrylic canopies arevacuum formed. A sheet of acrylic is secured to a female mould, then the entire assembly is heated in an oven until the acrylic is pliable. The air is then removed from the mould and the acrylic sheet is drawn into it, forming the shape of the canopy. The acrylic is then trimmed to the appropriate shape and attached to an aluminum or composite frame. Some one-off canopies are made in a similar fashion, but since a mould would be too time-consuming to make, the acrylic is heated and vacuum formed until it approximates the shape the builder is seeking. This type of construction is less precise, however, and each canopy is unique. If multiple canopies will be needed, a mould is almost always used.
Aircraft canopies have various opening methods:
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A clamshell canopy uses a hinge on the rear of the cockpit, with some examples from the front or side.[1][2] A more unusual example with two components with left and right sections requiring the pilot to enter the cockpit from the rear is found on thePayen PA-22 andAvro Arrow that used this method, the latter example for the use of ejection seats.[3][4]
Have Glass is the code name for a series of RCS reduction measures for the F-16 fighter. Its primary aspect is the addition of an indium-tin-oxide layer to the gold tinted cockpit canopy, which is reflective to radar frequencies. An ordinary canopy would let radar signals straight through where they would strike the many edges and corners inside and bounce back strongly to the radar source; the reflective layer dissipates these signals instead. Overall, Have Glass reduces an F-16's RCS (radar-cross section) by 15 percent. The gold tint also reduces glare from the sun to improve visibility for the pilot.[citation needed]
The Malcolm Hood is a type of aircraft canopy originally developed for theSupermarine Spitfire. Its concept proved valuable for other aircraft such as theNorth American Aviation P-51B & C Mustangs as retrofit items, and standard on later versions of theVought F4U Corsair, and somewhat emulated on the later models of theLuftwaffe'sFocke-Wulf Fw 190 fighter. The canopy was manufactured by the British companyR Malcolm & Co which gave its name. Instead of taking a straight line between the canopy frames, the hood was bulged outward. This gave the pilot a better view to the rear.
A bulged hood replaced the Vought Corsair's "birdcage" framed canopy from the 689th production F4U-1 to provide better all-round field of view.[5]
In the 1970s, US aviation artistKeith Ferris invented afalse canopy to paint on the underside of military aircraft, directly underneath the front of the plane, the purpose ofdeception which was tocamouflage the direction the aircraft is heading. This ruse was inspired by animals and fishes that have similar markings on the head and tail, so they can confuse other creatures. Pilots remain skeptical of this feature, asserting that if the enemy is close enough to see the marking, they are too close to be fooled by it.[citation needed]
Canada was the first operational user, painting CF-18s with a canopy on the bottom of the plane.
A type of canopy used as part of asynthetic cockpit where the pilot would not have direct sight of the outside world, but through an array of cameras. TheBritish Aerospace P.125 was to use thehave not glass cockpit arrangement that would increase stealth characteristics and would block out the potential soviet threat of dazzling laser weapons.
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