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85-491: The Canadair CT-114 Tutor (company model CL-41 ) is a jet trainer that was designed and produced by Canadian aircraft manufacturer Canadair . It served as the standard jet trainer of the Royal Canadian Air Force (RCAF), and later Canadian Armed Forces , between the early 1960s and 2000. Development commenced as a private venture by the company. On 13 January 1960, the prototype performed its maiden flight ;

170-507: 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

255-448: 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

340-477: 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

425-408: 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

510-464: A lack of official backing for the endeavour from the Canadian Government, the Royal Canadian Air Force 's (RCAF) Directorate of Training’s Jet Trainer Liaison Committee had closely engaged with Canadair; its involvement in the project had reportedly made a significant impact in the final design of the aircraft. Both the Canadian Government and Canadair committed financing towards the production of

595-409: 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,

680-417: 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

765-492: A pair of flight-capable prototypes, as well as multiple static airframes. This early manufacturing activity was performed in a secretive fashion at the company’s Plant 4 facility, which housed Canadair’s Missiles & Systems division. On 13 January 1960, the prototype performed its maiden flight , flown by project pilot Ian MacTavish. Originally, the first flight has been scheduled to take place in early 1959, but had been delayed due to issues relating to engine development. While

850-520: A private venture. The design was the product of the company’s in-house Preliminary Design department. By August 1957, the basic configuration of the design had been completed, which was of a turbojet -powered, low-wing aircraft, complete with a tricycle undercarriage and a side-by-side cockpit arrangement. From the onset of development, the aircraft was intended to be a purpose-built trainer for providing elementary jet flight training, as well as additional training up to an advanced level. Early on, despite

935-534: A proposed electronic systems trainer for future RCAF CF-104 pilots. A single airframe ( CF-LTX-X ) was constructed to demonstrate the concept, however, the R model did not attract any orders and thus never went into production.As of August 2019, the airframe was awaiting restoration at the Reynolds-Alberta Museum . Although the CL-41 Tutor has been retired from active training, 26 Tutors continue to fly with

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1020-432: 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

1105-482: 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

1190-493: 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

1275-433: A smoke generator, including a pair of under-fuselage pods to house the pressurized diesel fuel used; the use of red dye in the smoke was discontinued fairly quickly as it was found to be highly corrosive . Various other modifications would also be made to display aircraft; these could be routinely installed and uninstalled as airframes would regularly be exchanged between display and training flights. During September 1961,

1360-523: 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

1445-401: 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

1530-399: 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 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

1615-626: A support aircraft; all spares and useful material could be carried by the aircraft themselves in storage areas located in the nose or the wing root . Those Tutors used by the Snowbirds feature several modifications distinguishing them from standard examples; these include a smoke generating system , a highly-recognisable paint scheme unique to the display team, and a highly-tuned engine for greater responsiveness during low-level flying. Reportedly, display pilots would deliberately fly their aircraft using an above-average level of nose-down trim so that pushing

1700-583: A year and a half later, the Canadian Government placed a major order for the type. The RCAF would be the dominant user of the type, but a limited number were exported as well. Specifically, the CL-41G model, which was supplied to the Royal Malaysian Air Force (RMAF), served as a ground-attack aircraft up until its withdrawal. The Tutor served as the Canadian Armed Forces primary jet trainer from

1785-418: 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

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1870-438: 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

1955-476: Is a list of some current and former jet trainers Stall (fluid dynamics)#Speed In fluid dynamics , 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

2040-429: 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,

2125-417: 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

2210-480: 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

2295-421: 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

2380-428: Is intentionally aerodynamically stable in flight, a factor which traditionally has aided in the training of fresh pilots unfamiliar with the demands of flight. The Tutor features a side-by-side cockpit. During standard operations, the observing instructor was seated on the right-hand side and the student pilot on the left. Normally, only the left-hand side featured full flight controls. However, following experiences with

2465-447: 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

2550-433: 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

2635-536: Is the same even in an unpowered glider aircraft . Vectored thrust in aircraft 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

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2720-423: 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

2805-609: The Aerospace Engineering Test Establishment (AETE) at CFB Cold Lake , Alberta) and aerial display purposes. By 2019, there were 24 examples registered as in service with the RCAF. During 1967, a batch of ten Tutors were modified for use as a formation aerobatic aircraft by the RCAF (and later the unified Canadian Armed Forces ) display team, the Golden Centennaires to celebrate Canada's centennial year. At

2890-706: The Armstrong-Siddeley Viper ASV11 , the Continental Gabizo , the Rolls-Royce RB.108 , and the Fairchild J83-R-1 had been studied during the early stages of design work. During March 1960, an RCAF survey team performed a series of preliminary flight evaluations of the CL-41 prototype over the course of one week; prior to this, the team had evaluated various trainers from France, the United States, and

2975-703: The Cessna T-37 Tweet appeared for the early stages of pilot training. Pilots who were picked to fly fighter or strike aircraft then went on to fly more advanced training aircraft like the Hawker Siddeley Gnat . As the early jet-trainers became obsolete then further generations have appeared, the British using the single-engine BAE Systems Hawk while the French ordered the Dassault/Dornier Alpha Jet . In

3060-550: 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

3145-477: 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

3230-425: 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

3315-597: The 1940s were modified from existing designs like the Gloster Meteor and Lockheed T-33 but with these were followed by custom training aircraft like the Aero L-29 Delfín and the BAC Jet Provost . As training developed different air forces used jet trainers for different phases of training. Although most air forces continued to use piston or later turboprop aircraft for basic training, a number of jet trainers like

3400-541: The 1960s up until 2000, at which point it was finally retired from this role, having been replaced by a combination of the newer British-built CT-155 Hawk and American-built CT-156 Harvard II . While the majority of Tutors have been retired, a small number are still being used by the RCAF’s Snowbirds aerobatics team. The beginnings of the CL-41 Tutor can be found in a decision by Canadian aircraft manufacturer Canadair to develop its own indigenous trainer aircraft as

3485-933: The Canadian Armed Forces Snowbirds and the Aerospace Engineering Test Establishment at CFB Cold Lake or are in short-term storage. As of August 2011, there were three CL-41Gs and one CT-114 on the U.S. civil registry , while none were so registered in Canada. During 2001, a CL-41G was given to Embry-Riddle Aeronautical University in Daytona Beach, Florida , by actor John Travolta . Data from Macdonald Aircraft Handbook , Royal Canadian Air Force General characteristics Performance Armament Aircraft of comparable role, configuration, and era Related lists Jet trainer The first generation of trainers in

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3570-688: The Canadian government, having been impressed by the performance of the prototype and being keen to support local industry, placed a sizeable order for 190 examples of the production variant, referred to as the CL-41A , on behalf of the Royal Canadian Air Force (RCAF). Upon its adoption, the aircraft received the Canadian unified aircraft designation of CT-114 Tutor . The majority of the type was stationed at CFB Moose Jaw , Saskatchewan, in Western Canada;

3655-529: The Central Flying School at CFB Winnipeg , Manitoba, also made heavy use of the Tutor. Serving as a primary trainer platform, the Tutor was used in this capacity for over thirty years. During 1976, the Canadian Armed Forces decided to have 113 of the remaining aircraft furnished with upgraded avionics and provisions for a pair of belly-mounted 41 US gal (155 L) external fuel tanks . By 1998, it

3740-411: The Snowbirds display team has regularly performed at air shows and special events, including the annual flypast on Canada Day over the capital city, Ottawa. According to journalist Guy Norris, a defining trait of their aerobatics is the physically-demanding formation flights performed, as well as locally-developed manoeuvres such as the ‘Big Goose’. Unlike most display teams, the Snowbirds do not have

3825-428: The Snowbirds display team, a number of aircraft were reconfigured with extra controls so that they would be flyable from either position. The cabin, which is fitted with a rear-hinged canopy over both crew members, can be pressurized to a differential of 3 psi (20 kPa ), the equivalent to an altitude of about 2,000 m, for pilot comfort. For aerial display purposes, the Tutor was readily capable of being fitted with

3910-471: The United Kingdom as well. According to aviation historian Bill Upton, those who flew the prototype universally praised the aircraft for its favourable handling and performance. The prototypes were subject to an extensive regime of tests, some of which falling outside the traditional scope of such activities. The CT-114 Tutor is a single-engine turbojet -powered trainer aircraft. It was purpose-designed for

3995-404: 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

4080-588: The Warsaw Pact the Aero L-39 Albatros became the standard jet trainer. As the jet trainer developed it was also used for weapon training, which led to some trainers being modified as light strike aircraft; for example, the Cessna T-37 Tweet was developed into the Cessna A-37 Dragonfly . Modern jet trainers are structurally strengthened in order to allow high stress maneuvers and aerobatics. Below

4165-597: 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

4250-425: 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

4335-438: 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

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4420-631: The carriage of various external stores, including up to 4,000 lb (1814 kg) of weapons and drop tanks. During March 1966, the Royal Malaysian Air Force (RMAF) ordered a batch of twenty (serials M-22-01 to M22-11 ) examples of the CL-41G-5 Tebuan (which means Wasp in the Malay language ) aircraft as counterinsurgency (COIN) aircraft. In 1967, the Tebuan entered service in Malaysia . The RMAF operated

4505-575: 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

4590-417: 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),

4675-479: 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

4760-404: 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

4845-444: 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

4930-442: The end of the 1967 season, the display team was disbanded, thus its aircraft returned to routine training duties. In 1971, a new formation team was formed at 2CFFTS (Two Canadian Armed Forces Flying Training School) at CFB Moose Jaw, and once again adopted the type. The following year, the name " Snowbirds " was chosen for the team; during 1978, the team received squadron status as 431 Air Demonstration Squadron . Since its formation,

5015-432: 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

5100-413: 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

5185-409: 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

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5270-434: 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

5355-430: 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

5440-449: 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

5525-463: The prototype was powered by a single Pratt & Whitney JT12A-5 turbojet engine, this would be substituted for by a General Electric J85 powerplant for the subsequent production aircraft that followed. This change of engine had required no redesign as the fuselage had been developed to accommodate a wide range of engines without structural modification being necessary; in addition to the JT12A-5 and J85,

5610-473: 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

5695-422: 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

5780-458: 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

5865-502: 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

5950-437: 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

6035-422: The stick down would become unnecessary. The Snowbirds' aircraft would regularly be cycled with standard training aircraft, allowing the team to operate airframes with comparatively low accumulated flight hours. Canadair also developed an armament training and light attack variant, designated CL-41G . This model was powered by an uprated engine and fitted with underwing hard points , the latter of which allowed for

6120-413: The training role, and possesses numerous favourable qualities, including a high level of reliability and favourable operating economics. It is capable of a wide performance range, possessing a top speed at altitude of 795 kmh (429 kt) and a diving speed of 885 kmh (478 kt) against a relatively low stalling speed of 71kt. The Tutor is furnished with manual flight controls, which incorporate spring tabs . It

6205-423: 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

6290-469: The type in excess of twenty years, the last Tebuan being withdrawn from service during June 1986, having been replaced by the Italian Aermacchi MB-339 A. Following their retirement, the majority of the fleet was retained and placed into local storage for over a decade. One other experimental variant was developed, designated CL-41R , which was fitted with the nose of an F-104 Starfighter , as

6375-505: 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

6460-412: 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

6545-411: 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

6630-434: 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 )

6715-415: 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

6800-618: 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

6885-404: 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

6970-420: 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

7055-578: 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

7140-432: Was reported that around 120 examples of the type were still in regular service with the Canadian Armed Forces. During 2000, the majority of Tutors were retired, the type having been succeeded as the RCAF's principal training aircraft by a combination of the newer British-built CT-155 Hawk and American-built CT-156 Harvard II . Since then, it has continued to be used in limited numbers by the service for both experimental (by

7225-402: 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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