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83-628: The de Havilland DH.104 Dove is a British short-haul airliner developed and manufactured by de Havilland . The design, which was a monoplane successor to the pre-war Dragon Rapide biplane , came about from the Brabazon Committee report which, amongst other aircraft types, called for a British-designed short-haul feeder for airlines. The Dove was a popular aircraft and is considered to be one of Britain's most successful postwar civil designs, with over 500 aircraft manufactured between 1946 and 1967. Several military variants were operated, such as

166-417: A stall is a reduction in the lift coefficient generated by a foil as angle of attack exceeds its critical value . 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

249-596: A Paraguayan head of state during the rule of Alfredo Stroessner . It was subsequently replaced by a de Havilland Canada DHC-6 Twin Otter . A few Doves and civilianised Devons remained in use in 2011 in the United Kingdom, Canada, Germany and elsewhere with small commercial firms and with private pilot owners. Portuguese Angola Portuguese Cape Verde Portuguese Mozambique Portuguese Timor [REDACTED]   South Africa A de Havilland Dove featured prominently in

332-473: A configuration it was capable of seating five passengers; the executive model proved to be popular with various overseas customers, particularly those in the United States. The crew typically consisted of a pilot and radio operator , although rapidly removable dual flight controls could be installed for a second flying crewmember. A combination of large windows and a transparent perspex cabin roof provided

415-507: A deep stall. Two Velocity aircraft crashed due to locked-in deep stalls. Testing revealed that the addition of leading-edge cuffs to the outboard wing prevented the aircraft from getting into a deep stall. The Piper Advanced Technologies PAT-1, N15PT, another canard-configured aircraft, also crashed in an accident attributed to a deep stall. Wind-tunnel testing of the design at the NASA Langley Research Center showed that it

498-448: A dive. In these cases, the wings are already operating at a higher angle of attack to create the necessary force (derived from lift) to accelerate in the desired direction. Increasing the g-loading still further, by pulling back on the controls, can cause the stalling angle to be exceeded, even though the aircraft is flying at a high speed. These "high-speed stalls" produce the same buffeting characteristics as 1g stalls and can also initiate

581-450: A great-circle route extending northward towards the Arctic region. The apparent curve of the route is a result of distortion when plotted onto a conventional map projection and makes the route appear to be longer than it really is. Stretching a string between North America and Japan on a globe will demonstrate why this really is the shortest route despite appearances. The actual flight length

664-477: A helicopter blade may incur flow that reverses (compared to the direction of blade movement), and thus includes rapidly changing angles of attack. Oscillating (flapping) wings, such as those of insects like the bumblebee —may rely almost entirely on dynamic stall for lift production, provided the oscillations are fast compared to the speed of flight, and the angle of the wing changes rapidly compared to airflow direction. Stall delay can occur on airfoils subject to

747-408: A high angle of attack and a three-dimensional flow. When the angle of attack on an airfoil is increasing rapidly, the flow will remain substantially attached to the airfoil to a significantly higher angle of attack than can be achieved in steady-state conditions. As a result, the stall is delayed momentarily and a lift coefficient significantly higher than the steady-state maximum is achieved. The effect

830-523: A high level of visibility from the cockpit. From a piloting perspective, the Dove was noted for possessing easy flying qualities and mild stall qualities. A TKS anti-icing system was available for the Dove, involving an alcohol -based jelly delivered via porous metal strips embedded on the leading edges of the wings and tail. The Dove first flew on 25 September 1945. In December 1946, the Dove entered service with Central African Airways . Initial production of

913-409: A lower speed. A fixed-wing aircraft can be made to stall in any pitch attitude or bank angle or at any airspeed but deliberate stalling is commonly practiced by reducing the speed to the unaccelerated stall speed, at a safe altitude. Unaccelerated (1g) stall speed varies on different fixed-wing aircraft and is represented by colour codes on the airspeed indicator . As the plane flies at this speed,

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996-417: A multi-engine non-centreline thrust aircraft), or from less likely sources such as severe turbulence. The net effect is that one wing is stalled before the other and the aircraft descends rapidly while rotating, and some aircraft cannot recover from this condition without correct pilot control inputs (which must stop yaw) and loading. A new solution to the problem of difficult (or impossible) stall-spin recovery

1079-455: A non-stop flight between Papeete and Paris-Charles de Gaulle , using a Boeing 787-9 and covering 15,715 km (9,765 mi; 8,485 nmi). in a scheduled time of 16 hours and 20 minutes. As of 2023, it continues to hold the record for the longest ever scheduled commercial nonstop flight (by great circle distance) as well as the world's longest domestic flight . As of November 9, 2020, Singapore Airlines Flights 23 and 24

1162-432: A range of weights and flap positions, but the stalling angle of attack is not published. As speed reduces, angle of attack has to increase to keep lift constant until the critical angle is reached. The airspeed at which this angle is reached is the (1g, unaccelerated) stalling speed of the aircraft in that particular configuration. Deploying flaps /slats decreases the stall speed to allow the aircraft to take off and land at

1245-482: A risk of accelerated stalls. When an aircraft such as an Mitsubishi MU-2 is flying close to its stall speed, the sudden application of full power may cause it to roll, creating the same aerodynamic conditions that induce an accelerated stall in turning flight even if the pilot did not deliberately initiate a turn. Pilots of such aircraft are trained to avoid sudden and drastic increases in power at low altitude and low airspeed, as an accelerated stall under these conditions

1328-405: A single aircraft lavatory and an aft luggage compartment could be removed to provide increased seating. Various specialised models were produced for other roles, such as aerial survey , air ambulance , and flying classroom . A strengthened cabin floor structure was used to enable concentrated freight loads to be carried as well. The Dove could also serve as an executive transport , and in such

1411-437: A small loss in altitude (20–30 m/66–98 ft). It is taught and practised in order for pilots to recognize, avoid, and recover from stalling the aircraft. A pilot is required to demonstrate competency in controlling an aircraft during and after a stall for certification in the United States, and it is a routine maneuver for pilots when getting to know the handling of an unfamiliar aircraft type. The only dangerous aspect of

1494-523: A spin if there is also any yawing. Different aircraft types have different stalling characteristics but they only have to be good enough to satisfy their particular Airworthiness authority. For example, the Short Belfast heavy freighter had a marginal nose drop which was acceptable to the Royal Air Force . When the aircraft were sold to a civil operator they had to be fitted with a stick pusher to meet

1577-401: A stall is a lack of altitude for recovery. A special form of asymmetric stall in which the aircraft also rotates about its yaw axis is called a spin . A spin can occur if an aircraft is stalled and there is an asymmetric yawing moment applied to it. This yawing moment can be aerodynamic (sideslip angle, rudder, adverse yaw from the ailerons), thrust related (p-factor, one engine inoperative on

1660-418: Is 19% higher than V s . According to Federal Aviation Administration (FAA) terminology, the above example illustrates a so-called turning flight stall , while the term accelerated is used to indicate an accelerated turning stall only, that is, a turning flight stall where the airspeed decreases at a given rate. The tendency of powerful propeller aircraft to roll in reaction to engine torque creates

1743-438: Is a condition in aerodynamics and aviation such that if the angle of attack on an aircraft increases beyond a certain point, then lift begins to decrease. The angle at which this occurs is called the critical angle of attack . If the angle of attack increases beyond the critical value, the lift decreases and the aircraft descends, further increasing the angle of attack and causing further loss of lift. The critical angle of attack

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1826-429: Is caused by flow separation which, in turn, is caused by the air flowing against a rising pressure. Whitford describes three types of stall: trailing-edge, leading-edge and thin-aerofoil, each with distinctive Cl~alpha features. For the trailing-edge stall, separation begins at small angles of attack near the trailing edge of the wing while the rest of the flow over the wing remains attached. As angle of attack increases,

1909-417: Is dependent upon the airfoil section or profile of the wing, its planform , its aspect ratio , and other factors, but is typically in the range of 8 to 20 degrees relative to the incoming wind ( relative wind ) for most subsonic airfoils. The critical angle of attack is the angle of attack on the lift coefficient versus angle-of-attack (Cl~alpha) curve at which the maximum lift coefficient occurs. Stalling

1992-480: Is increased when the wing surfaces are contaminated with ice or frost creating a rougher surface, and heavier airframe due to ice accumulation. Stalls occur not only at slow airspeed, but at any speed when the wings exceed their critical angle of attack. Attempting to increase the angle of attack at 1g by moving the control column back normally causes the aircraft to climb. However, aircraft often experience higher g-forces, such as when turning steeply or pulling out of

2075-421: Is increased. Early speculation on reasons for the crash of Air France Flight 447 blamed an unrecoverable deep stall, since it descended in an almost flat attitude (15°) at an angle of attack of 35° or more. However, it was held in a stalled glide by the pilots, who held the nose up amid all the confusion of what was actually happening to the aircraft. Canard-configured aircraft are also at risk of getting into

2158-419: Is no international standard definition. The related term flight time is defined by ICAO (International Civil Aviation Organization) as "The total time from the moment an aeroplane first moves for the purpose of taking off until the moment it finally comes to rest at the end of the flight", and is referred to colloquially as "blocks to blocks" or " chocks to chocks" time. In commercial aviation, this means

2241-447: Is provided by the ballistic parachute recovery system. The most common stall-spin scenarios occur on takeoff ( departure stall) and during landing (base to final turn) because of insufficient airspeed during these maneuvers. Stalls also occur during a go-around manoeuvre if the pilot does not properly respond to the out-of-trim situation resulting from the transition from low power setting to high power setting at low speed. Stall speed

2324-433: Is reduced by the wing and nacelle wakes. He also gives a definition that relates deep stall to a locked-in condition where recovery is impossible. This is a single value of α {\textstyle \alpha } , for a given aircraft configuration, where there is no pitching moment, i.e. a trim point. Typical values both for the range of deep stall, as defined above, and the locked-in trim point are given for

2407-400: Is the length of the track flown across the ground in practice, which is usually longer than the ideal great-circle and is influenced by a number of factors such as the need to avoid bad weather, wind direction and speed, fuel economy, navigational restrictions and other requirements. In the example, easterly flights from Japan to North America are shown taking a longer, more southerly, route than

2490-540: Is the shortest commercial flight in the world, covering 2.8 km (1.7 mi) in two minutes scheduled flight time including taxiing. The world's longest ever commercial flight was Air Tahiti Nui Flight TN64 in early 2020. Due to the COVID-19 pandemic and the impossibility of transit in the United States through Los Angeles International Airport , Air Tahiti Nui scheduled and operated in March and April 2020 Flight TN64 as

2573-402: Is the world's longest active commercial flight between Singapore and New York–JFK , covering 15,349 km (9,537 mi; 8,288 nmi) in around 18 hours and 40 minutes, operated by an Airbus A350-900ULR . The shortest distance between two geographical points is the great-circle distance . In the example (right), the aircraft travelling westward from North America to Japan is following

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2656-452: Is used to maintain altitude or controlled flight with wings stalled by replacing lost wing lift with engine or propeller thrust , thereby giving rise to post-stall technology. Because stalls are most commonly discussed in connection with aviation , this article discusses stalls as they relate mainly to aircraft, in particular fixed-wing aircraft. The principles of stall discussed here translate to foils in other fluids as well. A stall

2739-423: Is very difficult to safely recover from. A notable example of an air accident involving a low-altitude turning flight stall is the 1994 Fairchild Air Force Base B-52 crash . Dynamic stall is a non-linear unsteady aerodynamic effect that occurs when airfoils rapidly change the angle of attack. The rapid change can cause a strong vortex to be shed from the leading edge of the aerofoil, and travel backwards above

2822-681: The Devon by the Royal Air Force and the Sea Devon by the Royal Navy , and the type also saw service with a number of overseas military forces. A longer four-engined development of the Dove, intended for use in the less developed areas of the world, was the Heron . A considerably re-designed three-engined variant of the Dove was built in Australia as the de Havilland Australia DHA-3 Drover . The development team for

2905-550: The Douglas DC-9 Series ;10 by Schaufele. These values are from wind-tunnel tests for an early design. The final design had no locked-in trim point, so recovery from the deep stall region was possible, as required to meet certification rules. Normal stall beginning at the "g break" (sudden decrease of the vertical load factor ) was at α = 18 ∘ {\textstyle \alpha =18^{\circ }} , deep stall started at about 30°, and

2988-574: The Gavin Lyall adventure novel Shooting Script . G-ARBH features in the 1962 film The Wrong Arm of the Law as the personal aeroplane of Peter Sellers ' character Pearly Gates. Near the beginning of the 1980 film Flash Gordon , travel agent Dale Arden and New York Jets quarterback Flash Gordon board a de Havilland Dove which subsequently crashes into a greenhouse adjacent to the secret laboratory of Dr. Hans Zarkov. The atmospheric disturbances that caused

3071-542: The Luxembourg to Bucharest route operated by Luxair , the scheduled flight length remains constant while the flight duration varies depending on aircraft used. On Thursday mornings, Luxair operates a DHC-8 turboprop with a scheduled duration of approximately 3 hours, while on Saturday mornings, Luxair's use of an Embraer 190 jet reduces the scheduled duration of the flight down to approximately 2 hours 20 minutes. Stall (fluid mechanics) In fluid dynamics ,

3154-477: The critical (stall) angle of attack . This speed is called the "stall speed". An aircraft flying at its stall speed cannot climb, and an aircraft flying below its stall speed cannot stop descending. Any attempt to do so by increasing angle of attack, without first increasing airspeed, will result in a stall. The actual stall speed will vary depending on the airplane's weight, altitude, configuration, and vertical and lateral acceleration. Propeller slipstream reduces

3237-425: The weight of the aircraft plus extra lift to provide the centripetal force necessary to perform the turn: where: To achieve the extra lift, the lift coefficient , and so the angle of attack, will have to be higher than it would be in straight and level flight at the same speed. Therefore, given that the stall always occurs at the same critical angle of attack, by increasing the load factor (e.g. by tightening

3320-507: The 1970s. The Biafran Air Force operated a single Dove during the Nigerian Civil War ; the aircraft was lost, to be subsequently found in 1970 on the premises of a school in Uli . A second US-registered Riley Dove, N477PM delivered in 1967 to Port Harcourt from Switzerland, never reached Biafra because it was stopped by Algerian authorities. A Dove served as the first official aircraft of

3403-424: The Dove took place at de Havilland's Hatfield factory, but from 1951 the aircraft were built at the company's Broughton facility near Chester . The final example of the type was delivered in 1967. Production of the Dove and its variants totalled 544 aircraft, including two prototypes, 127 military-orientated Devon s and 13 Sea Devon s. From 1946, large numbers were sold to scheduled and charter airlines around

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3486-461: The Dove was headed by Ronald Bishop , the creator of the de Havilland Mosquito , a wartime fighter-bomber, and the de Havilland Comet , the first commercial jet aircraft in the world. It had been developed to meet the Type VB requirement issued by the Brabazon Committee . In concept, the Dove was developed to be the replacement of the pre-war Dragon Rapide . It was also required to be competitive with

3569-580: The United States in 1954. In excess of 50 Doves were sold to various operators in the United States by Jack Riley, an overseas distributor for the type. De Havilland later assumed direct control of U.S. sales, but did not manage to match this early commercial success for the type. An early batch of 30 Devons was delivered to the Royal Air Force and they were used as VIP and light transports for over 30 years. The Royal New Zealand Air Force acquired 30 Devons between 1948 and 1954, and these remained in service for VIP, crew-training and light transport duties into

3652-404: The V S values above, always refers to straight and level flight, where the load factor is equal to 1g. However, if the aircraft is turning or pulling up from a dive, additional lift is required to provide the vertical or lateral acceleration, and so the stall speed is higher. An accelerated stall is a stall that occurs under such conditions. In a banked turn , the lift required is equal to

3735-597: The aircraft from recovering from the stall. Aircraft with rear-mounted nacelles may also exhibit a loss of thrust . T-tail propeller aircraft are generally resistant to deep stalls, because the prop wash increases airflow over the wing root, but may be fitted with a precautionary vertical tail booster during flight testing , as happened with the A400M . Trubshaw gives a broad definition of deep stall as penetrating to such angles of attack α {\textstyle \alpha } that pitch control effectiveness

3818-436: The aircraft's load-carrying capacity, safe engine-failure performance, and positive maintenance features. Considerable attention was paid to aspects of maintainability, many of the components being designed to be interchangeable and easy to remove or replace, such as the rudder , elevator , and power units; other areas include the mounting of the engines upon four quick-release pickup points, the routing of cables and piping, and

3901-425: The angle of attack exceeds the critical angle, the lift produced by the airfoil decreases. The information in a graph of this kind is gathered using a model of the airfoil in a wind tunnel . Because aircraft models are normally used, rather than full-size machines, special care is needed to make sure that data is taken in the same Reynolds number regime (or scale speed) as in free flight. The separation of flow from

3984-438: The angle of attack must be increased to prevent any loss of altitude or gain in airspeed (which corresponds to the stall angle described above). The pilot will notice the flight controls have become less responsive and may also notice some buffeting, a result of the turbulent air separated from the wing hitting the tail of the aircraft. In most light aircraft , as the stall is reached, the aircraft will start to descend (because

4067-575: The civil requirements. Some aircraft may naturally have very good behaviour well beyond what is required. For example, first generation jet transports have been described as having an immaculate nose drop at the stall. Loss of lift on one wing is acceptable as long as the roll, including during stall recovery, doesn't exceed about 20 degrees, or in turning flight the roll shall not exceed 90 degrees bank. If pre-stall warning followed by nose drop and limited wing drop are naturally not present or are deemed to be unacceptably marginal by an Airworthiness authority

4150-417: The crash of the prototype BAC 1-11 G-ASHG on 22 October 1963, which killed its crew. This led to changes to the aircraft, including the installation of a stick shaker (see below) to clearly warn the pilot of an impending stall. Stick shakers are now a standard part of commercial airliners. Nevertheless, the problem continues to cause accidents; on 3 June 1966, a Hawker Siddeley Trident (G-ARPY),

4233-801: The crash were instigated by planet Mongo's ruler Ming the Merciless. The crash sequence was filmed using a 30-inch-long model Dove diving into a miniature landscape. In season 2, episode 9 of the British TV series The Crown , Prince Philip is portrayed as flying a de Havilland Dove. Data from Flight International, Jane's All The World's Aircraft 1966–67, Jane's All the World's Aircraft 1967–68 General characteristics Performance Related development Short-haul Commercial flights are often categorized into long-, medium- or short-haul by commercial airlines based on flight length, although there

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4316-479: The critical angle of attack is reached (which in early-20th century aviation was called the "burble point"). This angle is 17.5 degrees in this case, but it varies from airfoil to airfoil. In particular, for aerodynamically thick airfoils (thickness to chord ratios of around 10%), the critical angle is higher than with a thin airfoil of the same camber . Symmetric airfoils have lower critical angles (but also work efficiently in inverted flight). The graph shows that, as

4399-404: The deep stall after deploying the anti-spin parachute but crashed after being unable to jettison the chute or relight the engines. One of the test pilots was unable to escape from the aircraft in time and was killed. On 26 July 1993, a Canadair CRJ-100 was lost in flight testing due to a deep stall. It has been reported that a Boeing 727 entered a deep stall in a flight test, but the pilot

4482-437: The detachable wings and tail cone. The extensive use of special Redux metal-bonding adhesives reduced the need for riveting during the manufacturing process, reducing overall weight and air-skin friction . While standard passenger versions of the Dove would carry between eight and eleven passengers, the cabin was designed to allow operators to convert between higher and lower density seating configurations. Features such as

4565-444: The downwash pattern associated with swept/tapered wings. To delay tip stall the outboard wing is given washout to reduce its angle of attack. The root can also be modified with a suitable leading-edge and airfoil section to make sure it stalls before the tip. However, when taken beyond stalling incidence the tips may still become fully stalled before the inner wing despite initial separation occurring inboard. This causes pitch-up after

4648-596: The large numbers of surplus military transports in the aftermath of the Second World War , such as the Douglas DC-3 . Unlike the Dragon Rapide, the Dove's structure was entirely metal. It featured innovations including constant-speed propellers , flaps , and a retractable tricycle undercarriage . In 1946, aviation magazine Flight praised the qualities of the newly developed Dove, noting its "modernity" as well as

4731-432: The lift to fall from its peak value. Piston-engined and early jet transports had very good stall behaviour with pre-stall buffet warning and, if ignored, a straight nose-drop for a natural recovery. Wing developments that came with the introduction of turbo-prop engines introduced unacceptable stall behaviour. Leading-edge developments on high-lift wings, and the introduction of rear-mounted engines and high-set tailplanes on

4814-413: The locked-in unrecoverable trim point was at 47°. The very high α {\textstyle \alpha } for a deep stall locked-in condition occurs well beyond the normal stall but can be attained very rapidly, as the aircraft is unstable beyond the normal stall and requires immediate action to arrest it. The loss of lift causes high sink rates, which, together with the low forward speed at

4897-409: The mean angle of attack of the wings is beyond the stall a spin , which is an autorotation of a stalled wing, may develop. A spin follows departures in roll, yaw and pitch from balanced flight. For example, a roll is naturally damped with an unstalled wing, but with wings stalled the damping moment is replaced with a propelling moment. The graph shows that the greatest amount of lift is produced as

4980-434: The next generation of jet transports, also introduced unacceptable stall behaviour. The probability of achieving the stall speed inadvertently, a potentially hazardous event, had been calculated, in 1965, at about once in every 100,000 flights, often enough to justify the cost of development of warning devices, such as stick shakers, and devices to automatically provide an adequate nose-down pitch, such as stick pushers. When

5063-430: The normal stall, give a high α {\textstyle \alpha } with little or no rotation of the aircraft. BAC 1-11 G-ASHG, during stall flight tests before the type was modified to prevent a locked-in deep-stall condition, descended at over 10,000 feet per minute (50 m/s) and struck the ground in a flat attitude moving only 70 feet (20 m) forward after initial impact. Sketches showing how

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5146-892: The opposite. Flight Haul Type terms are sometimes used when referring to commercial aircraft. Some commercial carriers choose to refer to their aircraft using flight haul type terms, for example: While they are capable of flying further, long-haul capable wide-bodies are often used on shorter trips. In 2017 - 40% of A350 routes were shorter than 2,000 nmi (2,300 mi; 3,700 km), 50% of A380 flights fell within 2,000–4,000 nmi (2,300–4,600 mi; 3,700–7,400 km), 70% of 777-200ER routes were shorter than 4,000 nmi (4,600 mi; 7,400 km), 80% of 787-9s routes were shorter than 5,000 nmi (5,800 mi; 9,300 km), 70% of 777-200LRs flights were shorter than 6,000 nmi (6,900 mi; 11,000 km). The Westray to Papa Westray flight in Orkney , operated by Loganair ,

5229-449: The pilot has actually stalled the aircraft. This graph shows the stall angle, yet in practice most pilot operating handbooks (POH) or generic flight manuals describe stalling in terms of airspeed . This is because all aircraft are equipped with an airspeed indicator , but fewer aircraft have an angle of attack indicator. An aircraft's stalling speed is published by the manufacturer (and is required for certification by flight testing) for

5312-428: The pilot increasing the wing's angle of attack or by a decrease in the critical angle of attack. The latter may be due to slowing down (below stall speed ) or the 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

5395-473: The real life counterparts often tend to overestimate the aerodynamic stall angle of attack. High-pressure wind tunnels are one solution to this problem. In general, steady operation of an aircraft at an angle of attack above the critical angle is not possible because, after exceeding the critical angle, the loss of lift from the wing causes the nose of the aircraft to fall, reducing the angle of attack again. This nose drop, independent of control inputs, indicates

5478-422: The separated regions on the top of the wing increase in size as the flow separation moves forward, and this hinders the ability of the wing to create lift. This is shown by the reduction in lift-slope on a Cl~alpha curve as the lift nears its maximum value. The separated flow usually causes buffeting. Beyond the critical angle of attack, separated flow is so dominant that additional increases in angle of attack cause

5561-399: The shorter great-circle; this is to take advantage of the favourable jet stream , a fast high-altitude tail-wind that assists the aircraft along its ground track saving more time or fuel than the geographically shortest route. Even for flights with the same origin and destination, a flight's duration can be affected by routing, wind, traffic, taxiing time, or aircraft used. For example, on

5644-458: The stall and entry to a super-stall on those aircraft with super-stall characteristics. Span-wise flow of the boundary layer is also present on swept wings and causes tip stall. The amount of boundary layer air flowing outboard can be reduced by generating vortices with a leading-edge device such as a fence, notch, saw tooth or a set of vortex generators behind the leading edge. Fixed-wing aircraft can be equipped with devices to prevent or postpone

5727-502: The stall speed by energizing the flow over the wings. Speed definitions vary and include: An airspeed indicator, for the purpose of flight-testing, may have the following markings: the bottom of the white arc indicates V S0 at maximum weight, while the bottom of the green arc indicates V S1 at maximum weight. While an aircraft's V S speed is computed by design, its V S0 and V S1 speeds must be demonstrated empirically by flight testing. The normal stall speed, specified by

5810-437: The stalling behaviour has to be made good enough with airframe modifications or devices such as a stick shaker and pusher. These are described in "Warning and safety devices". Stalls depend only on angle of attack, not airspeed . However, the slower an aircraft flies, the greater the angle of attack it needs to produce lift equal to the aircraft's weight. As the speed decreases further, at some point this angle will be equal to

5893-774: The time from pushing back at the departure gate to arriving at the destination gate. Flight time is measured in hours and minutes as it is independent of geographic distance travelled. Flight time can be affected by many things such as wind, traffic, taxiing time, and aircraft used. A flight's length can also be described using the aviation term of "Flight Haul Type", such as "short-haul" or "long-haul". Flight haul types can be defined using either flight distance or flight time. David W. Wragg classifies air services as medium-haul being between 1,600–4,000 km; 900–2,200 nmi; short-haul as being shorter and long-haul as being longer. David Crocker defines short-haul flights as shorter than 1,000 km (540 nmi), and long-haul as

5976-423: The turn) the critical angle will be reached at a higher airspeed: where: The table that follows gives some examples of the relation between the angle of bank and the square root of the load factor. It derives from the trigonometric relation ( secant ) between L {\displaystyle L} and W {\displaystyle W} . For example, in a turn with bank angle of 45°, V st

6059-505: The upper wing surface at high angles of attack is quite different at low Reynolds number from that at the high Reynolds numbers of real aircraft. In particular at high Reynolds numbers the flow tends to stay attached to the airfoil for longer because the inertial forces are dominant with respect to the viscous forces which are responsible for the flow separation ultimately leading to the aerodynamic stall. For this reason wind tunnel results carried out at lower speeds and on smaller scale models of

6142-412: The wing is no longer producing enough lift to support the aircraft's weight) and the nose will pitch down. Recovery from the stall involves lowering the aircraft nose, to decrease the angle of attack and increase the air speed, until smooth air-flow over the wing is restored. Normal flight can be resumed once recovery is complete. The maneuver is normally quite safe, and, if correctly handled, leads to only

6225-411: The wing tip, well aft of the c.g. If the tip stalls first the balance of the aircraft is upset causing dangerous nose pitch up . Swept wings have to incorporate features which prevent pitch-up caused by premature tip stall. A swept wing has a higher lift coefficient on its outer panels than on the inner wing, causing them to reach their maximum lift capability first and to stall first. This is caused by

6308-434: The wing wake blankets the tail may be misleading if they imply that deep stall requires a high body angle. Taylor and Ray show how the aircraft attitude in the deep stall is relatively flat, even less than during the normal stall, with very high negative flight-path angles. Effects similar to deep stall had been known to occur on some aircraft designs before the term was coined. A prototype Gloster Javelin ( serial WD808 )

6391-415: The wing. The vortex, containing high-velocity airflows, briefly increases the lift produced by the wing. As soon as it passes behind the trailing edge, however, the lift reduces dramatically, and the wing is in normal stall. Dynamic stall is an effect most associated with helicopters and flapping wings, though also occurs in wind turbines, and due to gusting airflow. During forward flight, some regions of

6474-493: The world, replacing and supplementing the pre-war designed de Havilland Dragon Rapide and other older designs. The largest order for the Dove was placed by Argentina, which ultimately took delivery of 70 aircraft, the majority of which were used by the Argentine Air Force . LAN Chile took delivery of twelve examples and these were operated from 1949 onwards until the aircraft were sold to several small regional airlines in

6557-618: Was lost to deep stall ; deep stall is suspected to be cause of another Trident (the British European Airways Flight 548 G-ARPI ) crash – known as the "Staines Disaster" – on 18 June 1972, when the crew failed to notice the conditions and had disabled the stall-recovery system. On 3 April 1980, a prototype of the Canadair Challenger business jet crashed after initially entering a deep stall from 17,000 ft and having both engines flame-out. It recovered from

6640-404: Was able to rock the airplane to increasingly higher bank angles until the nose finally fell through and normal control response was recovered. The crash of West Caribbean Airways Flight 708 in 2005 was also attributed to a deep stall. Deep stalls can occur at apparently normal pitch attitudes, if the aircraft is descending quickly enough. The airflow is coming from below, so the angle of attack

6723-420: Was first noticed on propellers . A deep stall (or super-stall ) is a dangerous type of stall that affects certain aircraft designs, notably jet aircraft with a T-tail configuration and rear-mounted engines. In these designs, the turbulent wake of a stalled main wing, nacelle-pylon wakes and the wake from the fuselage "blanket" the horizontal stabilizer, rendering the elevators ineffective and preventing

6806-578: Was lost in a crash on 11 June 1953 to a "locked-in" stall. However, Waterton states that the trimming tailplane was found to be the wrong way for recovery. Low-speed handling tests were being done to assess a new wing. Handley Page Victor XL159 was lost to a "stable stall" on 23 March 1962. It had been clearing the fixed droop leading edge with the test being stall approach, landing configuration, C of G aft. The brake parachute had not been streamed, as it may have hindered rear crew escape. The name "deep stall" first came into widespread use after

6889-402: Was vulnerable to a deep stall. In the early 1980s, a Schweizer SGS 1-36 sailplane was modified for NASA 's controlled deep-stall flight program. Wing sweep and taper cause stalling at the tip of a wing before the root. The position of a swept wing along the fuselage has to be such that the lift from the wing root, well forward of the aircraft center of gravity (c.g.), must be balanced by

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