Tuesday, January 06, 2015

Word of the Day -- Chandelle

The chandelle is an aircraft control maneuver where the pilot combines a 180° turn with a climb.
It is now required for attaining a commercial flight certificate in many countries. The Federal Aviation Administration in the United States requires such training.

The chandelle (which is the French word for candle) is a precision aircraft control maneuver, and not strictly speaking an aerobatic, dogfighting, or aerial combat maneuver. It is rather a maneuver designed to show the pilot's proficiency in controlling the aircraft while performing a minimum radius climbing turn at a constant rate of turn (expressed usually in degrees per second) through a 180° change of heading, arriving at the new reciprocal heading at an airspeed in the "slow-flight" regime, very near the aerodynamic stall. The aircraft can be flown in "slow-flight" after establishing the new heading, or normal cruise flight may be resumed, depending upon the purposes of the exercise or examination. See the diagram below for a visual depiction of how the maneuver must be flown for the purpose of certification.

The pilot enters a chandelle at a pre-determined airspeed in the normal cruising range for the aircraft. To begin the maneuver the pilot first rolls the aircraft in the desired direction with the controls (the ailerons), and quickly but smoothly establishes a medium banked turn. In most small aircraft (cruising speeds of 100–175 KIAS) this bank will be about 30° to 40°. This will begin a turn of the aircraft in the direction of bank. Simultaneously, full power is applied and a smooth pitch up is started with the controls (the elevators on the empennage). The angle of bank stays constant during the first 90° of the change of heading, while the pitch angle increases steadily. At the 90° point in the change of heading, the aircraft has the maximum pitch angle (which should be close to the critical angle of attack at the level stall speed of the aircraft). During the second 90° of the change of heading, the pitch angle is held constant, while the bank angle is smoothly decreased to reach 0° of bank, the end of the turn and return to straight-and-level flight at exactly the reciprocal heading (180° away from the heading at the start of the maneuver), and with the airspeed close to the stall speed. The aircraft should not lose altitude during the last part of the maneuver, nor during the recovery, when engine power may be used to re-establish normal cruising speed on the new heading. The decreasing bank angle together with the decreasing airspeed during the second half of the chandelle will maintain a constant turn rate. The turn needs to be kept coordinated by applying the correct amount of rudder throughout the maneuver.

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