Phantom from the Cockpit by Peter Caygill

Author:Peter Caygill
Language: eng
Format: mobi, epub
ISBN: 9781783409631
Publisher: Pen and Sword
Published: 2013-05-29T18:30:00+00:00

INVERTED STALLS

An inverted (negative angle of attack) stall can only be obtained with abrupt application of full forward stick in vertical manoeuvres or an inverted climb of greater than 20 degrees nose up. Light to moderate buffet occurs at the stall and there are no distinct yaw or roll tendencies. Recovery from the inverted stall is effected by relaxing the forward stick pressure and maintaining an angle of attack between 5 and 10 units until recovered from the unusual attitude.

LOSS OF CONTROL

A loss of control or departure from controlled flight is best described as random motions about any or all axes. Departure characteristics are highly dependent on airspeed, Mach number, ‘g’ level, type of entry and loading. In addition to the stall warning discussed under Normal and Accelerated Stalls, a build up in side forces (a tendency to move the pilot to the side of the cockpit) will be encountered immediately prior to departure. These may not be detectable in a high speed, high ‘g’ condition where wing rock will be the most positive indication of impending departure. If AOA is not reduced to below stall, departures can be expected to develop into spins. The AOA at departure is highly dependent on loading. Clean or Sparrows-only aeroplanes will depart at slightly greater than 30 units, while heavy wing loaded air-to-ground configurations may depart as low as 27 to 28 units. Departures are best prevented by proper control of AOA. Although aileron deflection may aggravate the situation, excessive AOA is the primary cause of departure. Use of ailerons, or excessive rudder deflection at departure, increase the probability of spin entry following departure.

Departures are characterised by a yawing motion with roll in the direction of yaw. The yawing motion at departure will be more violent when encountered during a high speed, high ‘g’ condition. At the first indication of departure, or when a nose high, rapidly decaying airspeed situation is encountered, attempt to reduce AOA by moving the stick smoothly forward, simultaneously neutralising ailerons and rudder. The throttles should be retarded to idle to reduce the probability of engine flame out unless, in the pilot’s opinion, the altitude is so low that thrust will be required to minimise altitude loss during the recovery. The stick should be smoothly, yet positively, moved forward; not jammed forward. Forward stick should be applied until negative ‘g’ is felt or until full forward stick is reached. The majority of recoveries will be effected before the stick reaches the forward stop. If recovery is not apparent after the application of full forward stick, deploy the drag chute without hesitation.

Large roll and yaw oscillations may be present during recoveries from departures. AOA indications will be erroneous during these oscillations and should not be used as a departure recovery indication. Applying full forward stick and neutralising ailerons and rudder is the most effective means of damping the oscillations and should be maintained until the oscillations cease. An out-of-control situation may be re-entered if stick movement off the forward stop is commenced prior to the aeroplane unloading and the oscillations ceasing.

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