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A pilot is performing flight tests on two airplanes: Airplane 1 and Airplane 2, which has double the mass of Airplane 1. While flying Airplane 1, the pilot performs a steady level turn with 18° angle of bank and notes the radius of turn using external visual cues and/or references. If the pilot performs the same steady level turn at the same TAS with Airplane 2, the required angle bank to maintain the same radius of turn would…
  • A
    be greater than 18°, because the centripetal force to maintain the same radius of turn will quadruple.
  • B
    be greater than 18°, because the centripetal force to maintain the same radius of the turn will increase by the same proportion.
  • C
    be less than 18°, because the centripetal force to maintain the same radius of turn will decrease by the same proportion.
  • D
    still be 18°, because the centripetal force to maintain the same radius of the turn will increase by the same proportion.

Refer to figure.
TURNING

For an aircraft to change direction, a force is required to deflect it towards the centre of the turn. This is called the centripetal force.

Banking the aircraft inclines the lift - it is the horizontal component of lift which causes the aircraft to turn. If the aircraft is banked and the angle of attack kept constant, the vertical component of lift will be too small to balance the weight and the aircraft will start to descend.

As the angle of bank increases, the angle of attack must be increased to bring about a greater total lift. The vertical component must be large enough to maintain level flight, while the horizontal component is large enough to produce the required centripetal force.

EFFECT OF WEIGHT ON TURNING

In a steady level turn, if thrust is ignored, lift provides a force to balance weight and centripetal force to turn the aircraft. If the same TAS and angle of bank can be obtained, the radius of turn is basically independent of weight or the aircraft type.

Not all aircraft can reach the same angle of bank at the same TAS. If weight increases, the vertical component of lift required increases, but the centripetal force to maintain the same radius of turn also increases in the same proportion. The lift required, although it is greater, has the same inclination to the vertical as before and the bank angle is the same.

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