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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, which suggested the Luftwaffe might attempt to re-open the bombing of England from high altitude. Construction was from 1942 to 1943. The threat never materialised; consequently, Westland produced only a small number of Welkins and few of these flew. Design and development Westland put forward their P.14, essentially an adaptation of Westland's Whirlwind fighter layout (and a more experimental twin, the P.13) to meet Air Ministry Specification F.4 of 1940 for a high altitude fighter. The most obvious feature was the enormous high aspect ratio wing, with a span on the production aircraft of . The compac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
WikiProject Aircraft
A WikiProject, or Wikiproject, is an affinity group for contributors with shared goals within the Wikimedia movement. WikiProjects are prevalent within the largest wiki, Wikipedia, and exist to varying degrees within Wikimedia project, sibling projects such as Wiktionary, Wikiquote, Wikidata, and Wikisource. They also exist in different languages, and translation of articles is a form of their collaboration. During the COVID-19 pandemic, CBS News noted the role of Wikipedia's WikiProject Medicine in maintaining the accuracy of articles related to the disease. Another WikiProject that has drawn attention is WikiProject Women Scientists, which was profiled by ''Smithsonian Magazine, Smithsonian'' for its efforts to improve coverage of women scientists which the profile noted had "helped increase the number of female scientists on Wikipedia from around 1,600 to over 5,000". On Wikipedia Some Wikipedia WikiProjects are substantial enough to engage in cooperative activities with outsi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rolls-Royce Merlin
The Rolls-Royce Merlin is a British Coolant#Liquids, liquid-cooled V12 engine, V-12 Reciprocating engine, piston aero engine of 27-litre (1,650 cu in) Engine displacement, capacity. Rolls-Royce Limited, Rolls-Royce designed the engine and first ran it in 1933 as a private venture. Initially known as the PV-12, it was later called ''Merlin (bird), Merlin'' following the company convention of naming its four-stroke piston aero engines after birds of prey. The engine benefitted from the racing experiences of precursor engines in the 1930s. After several modifications, the first production variants of the PV-12 were completed in 1936. The first operational aircraft to enter service using the Merlin were the Fairey Battle, Hawker Hurricane and Supermarine Spitfire. The Merlin remains most closely associated with the Spitfire and Hurricane, although the majority of the production run was for the four-engined Avro Lancaster heavy bomber. The Merlin continued to benefit from a s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shock-stall
A shock stall is a stall created when the airflow over an aircraft's wings is disturbed by shock waves formed when flying at or above the aircraft's drag divergence Mach number. Shock stall may cause control problem during speed transition (transonic to supersonic). Thin supercritical wing section and swept-back wing can postpone shock stall to higher speed. A stall is the decrease in lift to a value below the weight, and the associated increase in drag upon the separation of the boundary layer (in this case behind the shock wave In physics, a shock wave (also spelled shockwave), or shock, is a type of propagating disturbance that moves faster than the local speed of sound in the medium. Like an ordinary wave, a shock wave carries energy and can propagate through a me ...). A shock stall occurs, when the lift coefficient as function of the Mach Number reaches its maximum value. References Aerodynamics {{aviation-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stall (flight)
In fluid dynamics, a stall is a reduction in the lift coefficient generated by a foil as angle of attack exceeds its critical value.Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', p. 486. Aviation Supplies & Academics, 1997. The critical angle of attack is typically about 15°, but it may vary significantly depending on the fluid, foil – including its shape, size, and finish – and Reynolds number. Stalls in fixed-wing aircraft are often experienced as a sudden reduction in lift. It may be caused either by the pilot increasing the wing's angle of attack or by a decrease in the critical angle of attack. The former may be due to slowing down (below stall speed), the latter by accretion of ice on the wings (especially if the ice is rough). A stall does not mean that the engine(s) have stopped working, or that the aircraft has stopped moving—the effect is the same even in an unpowered glider aircraft. Vectored thrust in aircraft is used to maintain alti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flight Envelope
In aerodynamics, the flight envelope, service envelope, or performance envelope of an aircraft or spacecraft refers to the capabilities of a design in terms of airspeed and load factor or atmospheric density, often simplified to altitude. The term is somewhat loosely applied, and can also refer to other measurements such as maneuverability. For example, when a plane is pushed, for instance by diving it at high speeds, it is said to be flown "outside the envelope", something considered rather dangerous. During vehicle test programs, flight envelope simply means that part of the aircraft or spacecraft's design capabilities that have already been successfully tested, and have therefore moved from theoretical or designed capability into a demonstrated/certified capability. Flight envelope is one of a number of related terms that are used in a similar fashion. It is perhaps the most common term because it is the oldest, first being used in the early days of test flight. It is clos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thickness-to-chord Ratio
In aeronautics, the thickness-to-chord ratio, sometimes simply chord ratio or thickness ratio, compares the maximum vertical thickness of a wing to its chord. It is a key measure of the performance of a wing planform when it is operating at transonic speeds. At speeds approaching the speed of sound, the effects of Bernoulli's principle over curves on the wing and fuselage can accelerate the local flow to supersonic speeds. This creates a shock wave that produces a powerful form of drag known as wave drag, and gives rise to the concept of the sound barrier. The speed at which these shocks first form, critical mach, is a function of the amount of curvature. In order to reduce wave drag, wings should have the minimum curvature possible while still generating the required amount of lift. So, the main reason for decreasing the blade section thickness to chord ratio is to delay the compressibility effect related to higher Mach numbers, delaying the onset of a shock wave formation. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hispano 20 Mm Cannon
The HS.404 is an autocannon originally designed by and produced by the Swiss arm of the Spanish/Swiss company Hispano-Suiza in the mid-1930s. Production was later moved to the French arm of Hispano-Suiza. It was widely used as an aircraft, naval and land-based weapon by French, British, American and other military services, particularly during World War II. The cannon is also referred to as Birkigt type 404, after its designer Marc Birkigt and later versions based on British development are known as 20 mm Hispano. Firing a 20 mm calibre projectile, it delivered a significant load of explosive from a relatively light weapon. This made it an ideal anti-aircraft weapon for mounting on light vehicles, as well as a fighter aircraft gun, supplementing or replacing the 7.62 mm (.30 calibre) and .303 inch (7.7 mm) machine guns commonly used in military aircraft of the 1930s. The HS.404 was produced by the French subsidiary of Hispano-Suiza, and under license by a variety of c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Moment (physics)
A moment is a mathematical expression involving the product of a distance and a physical quantity such as a force or electric charge. Moments are usually defined with respect to a fixed reference point and refer to physical quantities located some distance from the reference point. For example, the moment of force, often called torque, is the product of a force on an object and the distance from the reference point to the object. In principle, any physical quantity can be multiplied by a distance to produce a moment. Commonly used quantities include forces, masses, and electric charge distributions; a list of examples is provided later. Elaboration In its most basic form, a moment is the product of the distance to a point, raised to a power, and a physical quantity (such as force or electrical charge) at that point: : \mu_n = r^n\,Q, where Q is the physical quantity such as a force applied at a point, or a point charge, or a point mass, etc. If the quantity is not concen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flap (aircraft)
A flap is a high-lift device used to reduce the stall (flight), stalling speed of an aircraft wing at a given weight. Flaps are usually mounted on the wing trailing edges of a fixed-wing aircraft. Flaps are used to reduce the take-off distance and the landing distance. Flaps also cause an increase in Drag (physics), drag so they are retracted when not needed. The flaps installed on most aircraft are partial-span flaps; spanwise from near the wing root to the inboard end of the ailerons. When partial-span flaps are extended they alter the spanwise lift distribution on the wing by causing the inboard half of the wing to supply an increased proportion of the lift, and the outboard half to supply a reduced proportion of the lift. Reducing the proportion of the lift supplied by the outboard half of the wing is accompanied by a reduction in the angle of attack on the outboard half. This is beneficial because it increases the margin above the Stall (fluid dynamics), stall of the outbo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cabin Pressurization
Cabin pressurization is a process in which conditioned air is pumped into the aircraft cabin, cabin of an aircraft or spacecraft in order to create a safe and comfortable environment for humans flying at high altitudes. For aircraft, this air is usually Bleed air, bled off from the gas turbine, gas turbine engines at the compressor stage, and for spacecraft, it is carried in high-pressure, often liquid oxygen, cryogenic, tanks. The air is cooled, humidified, and mixed with recirculated air by one or more Environmental control system (aircraft), environmental control systems before it is distributed to the cabin. The first experimental pressurization systems saw use during the 1920s and 1930s. In the 1940s, Boeing 307 Stratoliner, the first commercial aircraft with a pressurized cabin entered service. The practice would become widespread a decade later, particularly with the introduction of the British de Havilland Comet jetliner in 1949. However, South African Airways Flight 201 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rotol
Dowty Propellers is a British engineering company based in Brockworth, Gloucestershire that specialises in the manufacture, repair and overhaul of propellers and propeller components for customers around the world. It is owned by GE Aerospace. History The company was formed as Rotol Airscrews in 1937 by Rolls-Royce and Bristol Engines to take over both companies' propeller development, the market being too small to support more than one company. The name is a contraction of "Rolls-Royce" and "Bristol". Rotol's propellers were always considered leading edge, its models equipping the Hawker Hurricane, Supermarine Spitfire, and many other Second World War-era aircraft. By the end of the war it had introduced the first five-bladed propeller to see widespread use, used on late-model Spitfires. In 1943 the company changed its name from Rotol Airscrews Limited to Rotol Limited, and in 1952 it acquired British Messier Limited, a specialist in landing gear and hydraulics. In 1958, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vickers Type 432
The Vickers Type 432 was a British high-altitude fighter aircraft developed by the Vickers group during the Second World War. Intended to enable the Royal Air Force to engage the enemy's high-altitude bomber aircraft, it was to be armed with six cannon. Design and development The origins of the Type 432 lay with a requirements set out in 1939 for twin-engined fighters with 20 or possibly 40 mm cannon. Vickers had set out a proposal for a Griffon-engined aircraft, equipped with a 40 mm cannon in a flexible mounting. This was subsequently encouraged by the Air Ministry. Further development was carried out for a design that could also meet F.6/39 for a fixed gun fighter with 20mm cannon. Specification F.22/39 was drawn up to cover the 40 mm project as the Vickers 414 to meet Operational Requirement (OR) 76. This was subsequently revised with aircraft redesigns to become specifications F.16/40 and then F.7/41 for OR. 108. In appearance it resembled a larger version of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
