Aircraft canopy

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The bubble canopy of a Lockheed Martin F-22 Raptor F-22 cockpit close-up.jpg
The bubble canopy of a Lockheed Martin F-22 Raptor
Canopy of an F-22 Raptor 150904-F-RN211-373 (21310751252).jpg
Canopy of an F-22 Raptor

An aircraft canopy is the transparent enclosure over the cockpit of some types of aircraft. An aircraft canopy provides a controlled and sometimes pressurized 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 minimize aerodynamic drag, while maximizing visibility for pilots and other crewmembers.

Contents

History

The raised canopy of a Van's Aircraft RV-7 Vans.rv-7a.g-jfrv.arp.jpg
The raised canopy of a Van's Aircraft RV-7

Very early aircraft had no canopies at all. The pilots were exposed to the wind and weather, although most flying was done in good weather. Through World War I most aircraft had no canopy, although they often had a small windshield to deflect the prop 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 of flat glass held in position by a frame and muntins. The muntins reduced visibility, which was especially problematic for military aircraft. Also, glass canopies were much heavier than acrylic canopies, which were first introduced shortly before World War II. The acrylic bubble canopy was used on aircraft such as the Supermarine Spitfire and Westland Whirlwind, which gave better all-round visibility and reduced weight. It is still being used today on most fighter aircraft.

CF-18 Hornet of the RCAF displaying a false canopy McDonnell Douglas CF-188 Hornet, Canada - Air Force JP7645832.jpg
CF-18 Hornet of the RCAF displaying a false canopy

In the 1970s, US aviation artist Keith Ferris invented a false canopy to paint on the underside of military aircraft, directly underneath the front of the plane, the purpose of which was to confuse an enemy so they do not know in what direction the aircraft is headed. 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 ]

Ejection seat system

A cockpit view from a BAE Hawk showing the explosive cord in the canopy View from the cockpit of a Hawk TMK1.jpg
A cockpit view from a BAE Hawk showing the explosive cord in the canopy

On many high-performance military aircraft, the canopy is an integral part of the ejection seat system. The pilot cannot be ejected from the aircraft 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 by explosive charges. The relative wind then blows the canopy away from the ejection path. However, on some aircraft, such as the McDonnell 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 of plastic 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.

Construction

F-15 Eagle canopy Crew chief Staff Sgt. Jason Carlson waits for Capt. Grant Lewis to exit so he can put his F-15 Eagle to bed for the evening.JPG
F-15 Eagle canopy

Most modern acrylic canopies are vacuum 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.

Stealth canopy

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 some 15 percent. The gold tint also reduces glare from the sun to improve visibility for the pilot.[ citation needed ]

Malcolm Hood

This Spitfire is equipped with a Malcolm Hood. Kbely museum spitfire 310.jpg
This Spitfire is equipped with a Malcolm Hood.

The Malcolm Hood is a type of aircraft canopy originally developed for the Supermarine Spitfire. Its concept proved valuable for other aircraft such as the North American Aviation-produced P-51B & C Mustangs as retrofit items, and standard on later versions of the Vought F4U Corsair, and somewhat emulated on the later models of the Luftwaffe's Focke-Wulf Fw 190 fighter.

The canopy was manufactured by the British company R 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.

...the Corsair's initial deficiencies were being worked out on a concurrent basis... The 689th production F4U-1 featured a number of significant changes. The most noticeable was that the cockpit was raised 18 centimeters (7.1 inches) to improve the pilot's forward view, and a bulged canopy, along the lines of the "Malcolm Hood" used on Spitfires, replaced the original "birdcage" framed canopy to provide better all-round field of view. [1]

See also

Related Research Articles

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Westland Welkin

The Westland Welkin was a British twin-engine heavy fighter from the Westland Aircraft Company, designed to fight at extremely high altitudes, in the stratosphere; the word welkin meaning "the vault of heaven" or the upper atmosphere. First conceived in 1940, the plane was built in response to the arrival of modified Junkers Ju 86P bombers flying reconnaissance missions that suggested the Luftwaffe might attempt to re-open the bombing of England from high altitude. Construction was from 1942–43. The threat never materialised; consequently, Westland produced only a small number of Welkins and few of these flew.

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Ejection seat Emergency aircraft escape system

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Supermarine Attacker Carrier-based fighter aircraft; first jet fighter in Royal Navy service

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Supermarine Spitfire (late Merlin-powered variants) Late Merlin-powered variants of the Supermarine Spitfire

The British Supermarine Spitfire was facing several challenges by mid-1942. The debut of the formidable Focke-Wulf Fw 190 in late 1941 had caused problems for RAF fighter squadrons flying the latest Spitfire Mk Vb. Rolls-Royce engineers were already working on a new version of the Merlin incorporating a two-stage supercharger; the combination of the improved Merlin and the Spitfire Mk VC airframe in a "stop-gap" design allowed the RAF to combat the Fw 190 on equal terms.

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Grumman XF5F Skyrocket

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Bubble canopy

A bubble canopy is a canopy constructed without bracing, for the purpose of providing a wider unobstructed field of view to the pilot, often providing 360° all-round visibility.

Supermarine Type 224

The Supermarine Type 224 was an inverted gull-wing monoplane fighter aircraft designed by R.J. Mitchell at Supermarine in response to Air Ministry Specification F.7/30, which sought a fighter for introduction to succeed the Gloster Gauntlet. It was powered by the Rolls-Royce Goshawk engine, which used an experimental evaporative cooling system, and problems with this system, combined with its disappointing performance, led to it being rejected, a contract for production aircraft eventually going to the Gloster Gladiator. It is nevertheless notable because R.J. Mitchell learnt lessons from its failure that were to contribute greatly to his success with the Supermarine Spitfire.

Supermarine Spitfire (early Merlin-powered variants) Early variants of the Supermarine Spitfire

The British Supermarine Spitfire was the only Allied fighter aircraft of the Second World War to fight in front line service from the beginnings of the conflict, in September 1939, through to the end in August 1945. Post-war, the Spitfire's service career continued into the 1950s. The basic airframe proved to be extremely adaptable, capable of taking far more powerful engines and far greater loads than its original role as a short-range interceptor had called for. This would lead to 19 marks of Spitfire and 52 sub-variants being produced throughout the Second World War, and beyond. The many changes were made in order to fulfil Royal Air Force requirements and to successfully engage in combat with ever-improving enemy aircraft. With the death of the original designer, Reginald J. Mitchell, in June 1937, all variants of the Spitfire were designed by his replacement, Joseph Smith, and a team of engineers and draftsmen.

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SZD-24 Foka

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Supermarine Spitfire British single-seat WWII fighter aircraft

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Martin-Baker Mk.1 British ejection seat

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References

  1. host, just. "Welcome vectorsite.net - Justhost.com". www.vectorsite.net. Archived from the original on 22 December 2017. Retrieved 6 May 2018.