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Performance 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 (aeronautics), 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. 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. Flight envelope is one of a number of related terms that are all 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 flying. It is closely related to more modern terms known as extra power and a doghouse plot which are different ways of describing a flight envelope. In addition, the term has been widened in scope outside the field of engineering, to refer to the strict limits in which an ev ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lift (force)
A fluid flowing around an object exerts a force on it. Lift is the component of this force that is perpendicular to the oncoming flow direction. It contrasts with the drag force, which is the component of the force parallel to the flow direction. Lift conventionally acts in an upward direction in order to counter the force of gravity, but it can act in any direction at right angles to the flow. If the surrounding fluid is air, the force is called an aerodynamic force. In water or any other liquid, it is called a hydrodynamic force. Dynamic lift is distinguished from other kinds of lift in fluids. Aerostatic lift or buoyancy, in which an internal fluid is lighter than the surrounding fluid, does not require movement and is used by balloons, blimps, dirigibles, boats, and submarines. Planing lift, in which only the lower portion of the body is immersed in a liquid flow, is used by motorboats, surfboards, windsurfers, sailboats, and water-skis. Overview A fluid flowing arou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aircraft Wing Design
An aircraft is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines. Common examples of aircraft include airplanes, helicopters, airships (including blimps), gliders, paramotors, and hot air balloons. The human activity that surrounds aircraft is called ''aviation''. The science of aviation, including designing and building aircraft, is called ''aeronautics.'' Crewed aircraft are flown by an onboard pilot, but unmanned aerial vehicles may be remotely controlled or self-controlled by onboard computers. Aircraft may be classified by different criteria, such as lift type, aircraft propulsion, usage and others. History Flying model craft and stories of manned flight go back many centuries; however, the first manned ascent — and safe descent — in modern times took place by larger hot-air ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aerospace Engineering
Aerospace engineering is the primary field of engineering concerned with the development of aircraft and spacecraft. It has two major and overlapping branches: aeronautical engineering and astronautical engineering. Avionics engineering is similar, but deals with the electronics side of aerospace engineering. "Aeronautical engineering" was the original term for the field. As flight technology advanced to include vehicles operating in outer space, the broader term "aerospace engineering" has come into use. Aerospace engineering, particularly the astronautics branch, is often colloquially referred to as "rocket science". Overview Flight vehicles are subjected to demanding conditions such as those caused by changes in atmospheric pressure and temperature, with structural loads applied upon vehicle components. Consequently, they are usually the products of various technological and engineering disciplines including aerodynamics, Air propulsion, avionics, materials science, stru ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Corner Case
In engineering, a corner case (or pathological case) involves a problem or situation that occurs only outside normal operating parameters—specifically one that manifests itself when multiple environmental variables or conditions are simultaneously at extreme levels, even though each parameter is within the specified range for that parameter. For example, a loudspeaker might distort audio, but only when played at maximum volume, maximum bass, and in a high-humidity environment. Or a computer server may be unreliable, but only with the maximum complement of 64 processors, 512 GB of memory, and 10,000 signed-on users. The investigation of corner cases is of extreme importance as it can provide engineers with valuable insight into how corner case effects can be mitigated. In the case where automotive radar fails, corner case investigation can possibly tell engineers and investigators alike what may have occurred. Corner cases form part of an engineer's lexicon—especially an en ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Manoeuvring Speed
In aviation, the maneuvering speed of an aircraft is an airspeed limitation selected by the designer of the aircraft. At speeds close to, and faster than, the maneuvering speed, full deflection of any flight control surface should not be attempted because of the risk of damage to the aircraft structure.Federal Aviation AdministrationAdvisory Circular 23-19A, ''Airframe Guide for Certification of Part 23 Airplanes'', Section 48 (p.27)Retrieved 2012-01-06 The maneuvering speed of an aircraft is shown on a cockpit placard and in the aircraft's flight manual but is not commonly shown on the aircraft's airspeed indicator. In the context of air combat maneuvering (ACM), the maneuvering speed is also known as corner speed or cornering speed. Implications It has been widely misunderstood that flight below maneuvering speed will provide total protection from structural failure. In response to the destruction of American Airlines Flight 587, a CFR Final Rule was issued clarifying th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Küssner Effect
In fluid dynamics, the Küssner effect describes the wikt:unsteady, unsteady aerodynamics, aerodynamic forces on an airfoil or hydrofoil caused by encountering a transverse Wind#Measurement, gust. This is directly related to the Küssner function, used in describing the effect. Both the effect and function are named after Hans Georg Küssner (1900–1984), a German aerodynamics engineer. Küssner derived an approximate model for an airfoil encountering a sudden step-like change in the transverse gust velocity; or, equivalently, as seen from a frame of reference moving with the airfoil: a sudden change in the angle of attack. The airfoil is modelled as a flat plate in a potential flow, moving with constant horizontal velocity. For this case he derived the impulse response function (known as Küssner functionBisplinghoff, Ashley and Halfman (1996) pp. 287–288.) needed to compute the unsteady lift (force), lift and torque, moment exerted by the air on the airfoil. Notes Referenc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helicopter Height–velocity Diagram
The FAA states "The height–velocity diagram or H/V curve is a graph charting the safe/unsafe flight profiles relevant to a specific helicopter. As operation outside the safe area of the chart can be fatal in the event of a power or transmission failure it is sometimes referred to as the dead man's curve." The EASA refers to it as the "height/velocity avoid curve". The H–V curve is a diagram indicating the combinations of height above ground and airspeed that should be avoided due to safety concerns relating to emergency landings. It is dangerous to operate within the shaded regions of the diagram, because it may be impossible for the pilot to complete an emergency autorotation from a starting point within these regions. The H–V curve also contains a take-off profile, indicating how a pilot can start from 0 height and 0 speed, and safely traverse to cruise. At low heights with low airspeed, such as a hover taxi, the pilot can simply cushion the landing with collective by conve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coffin Corner (aviation)
Coffin corner (also known as the aerodynamic ceiling or Q corner) is the region of flight where a fast but subsonic fixed-wing aircraft's stall speed is near the critical Mach number, at a given gross weight and G-force loading. In this region of flight, it is very difficult to keep an airplane in stable flight. Because the stall speed is the minimum speed required to maintain level flight, any reduction in speed will cause the airplane to stall and lose altitude. Because the critical Mach number is the maximum speed at which air can travel over the wings without losing lift due to flow separation and shock waves, any increase in speed will cause the airplane to lose lift, or to pitch heavily nose-down, and lose altitude. The "corner" refers to the triangular shape at the top of a flight envelope chart where the stall speed and critical Mach number are within a few knots of each other. The "coffin" refers to the possible death in these kinds of stalls. The speed where they mee ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plus Ultra (motto)
''Plus ultra'' (, , en, "Further beyond") is a Latin phrase and the national motto of Spain. A reversal of the original phrase ''non plus ultra'' ("Nothing further beyond"), said to have been inscribed as a warning on the Pillars of Hercules at the Strait of Gibraltar (which marked the edge of the known world in antiquity), it has metaphorical suggestions of taking risks and striving for excellence. Its original version, the personal motto of the Holy Roman Emperor Charles V, also Duke of Burgundy and King of Spain, was ''Plus oultre'' in French. The motto was adopted some decades after the discovery of the New World by Christopher Columbus. History ''Plus oultre'', French for "further beyond", was adopted by the young Duke of Burgundy and new King of Spain Charles of Habsburg as his personal motto at the suggestion of his adviser Luigi Marliano, an Italian physician, in 1516. It was emblematic of Marliano's vision of a Christian empire spanning beyond the boundaries of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
General Aviation
General aviation (GA) is defined by the International Civil Aviation Organization (ICAO) as all civil aviation aircraft operations with the exception of commercial air transport or aerial work, which is defined as specialized aviation services for other purposes. However, for statistical purposes ICAO uses a definition of general aviation which includes aerial work. General aviation thus represents the "private transport" and recreational components of aviation. Definition The International Civil Aviation Organization (ICAO) defines civil aviation aircraft operations in three categories: General Aviation (GA), Aerial Work (AW) and Commercial Air Transport (CAT). Aerial work operations are separated from general aviation by ICAO by this definition. Aerial work is when an aircraft is used for specialized services such as agriculture, construction, photography, surveying, observation and patrol, search and rescue, and aerial advertisement. However, for statistical purposes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Army Aviation Branch
The United States Army Aviation Branch is the administrative organization within the United States Army responsible for doctrine, manning and configuration for all army aviation units. After the United States Army Air Corps grew into the United States Army Air Forces, Army Air Forces and split into the new service, the United States Air Force, the Army was left with its sole Fixed-wing aircraft, fixed-wing aviation units flying Taylorcraft L-2 Grasshopper observation planes for artillery units. The Army would develop a new concept of aviation using the helicopter that would show promise during the Korean War and would revolutionize warfare during the Vietnam War. History Origins of Army Aviation Army Aviation traces its origins back to the American Civil War. Both Union and Confederate forces used hydrogen-filled balloons to direct artillery fire, marking the beginning of U.S. military aeronautics and of aerial support of Army ground forces. The Army also used balloons during t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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