Ch 27 - Asymmetric Flight

Question 1

Yawning Moments (caused by engine failure)

Answer 1

Thrust acting from a distance away from the CG creates a yawning moment. Size of yawning moment depends on:

Engine thrust - high power setting produces greater thrust and therefore greater yawning moment

Engine Position - further away from CG produces a larger yaw

Drag - Increased drag from inoperative engine / prop can cause yawning towards dead engine

Question 2

Achieving Equilibrium - Wings level method

Answer 2

More useful on transport jets

Forcing dead engine side forward and side slipping

Adv; Strong visual cues instruments and horizon,

Disadvantage; Increased drag from fin reduces excess thrust, fin must be at a large AoA to produce sufficient force which could stall it

Question 3

Achieving Equilibrium - Banking Method

Answer 3

Used on smaller twins as it produces a greater performance margin due to the less drag from rudder inputs which improves climbing performance.

Balanced with rudder and thrust, banked over no more then 5’ towards live engine, sideways component of lift which counterbalances the side Force

Adv; Reduced drag and better climb performance, greater rudder authority and less chance of fin stall.

Disadvantage; increased risk of disorientation because of the one wing low, attitude indicator may erect itself to a false datum and fell a slight out of balance force

Question 4

Engine Failure and Angle of Climb

Answer 4

Sin (AoC) = T-D/W

JET; Large decrease in excess thrust, best speed for climb (Vx) is Vmd but the curve has moved up and left so now slightly slower - VXSE

Propeller AC; Curve up and left, VXSE is slightly faster than Vx - must feather dead propeller, if not, drag may totally overcome thrust meaning that climbing is not possible and that a forced landing may be your only option

Question 5

The Critical Engine

Answer 5

The critical engine is the engine that, if it fails, leaves the engine which produces the largest yaw.

Propeller AC; if the props rotate in the same direction, at slow speed and high AoA, the thrust line will be offset due to the P Factor which creates a large yawing moment.

Jet; Don’t suffer from P Factor but in a crosswind, the aircraft will have a natural tendency to yaw to the wind (weathercock), the critical engine is the into wind engine

Question 6

Minimum control speed in the Air Vmca

Answer 6

Calibrated AS when the critical engine is made inoperative it is possible to maintain control and not bank more than 5’

Does not exceed 1.13SR

• max available TO thrust or power on operating engine
• Most unfavourable CG Position
• Trimmed for TO
• Max sea level TO Mass
• Critical TO position but with gear up
• Out of Ground effect
• Feathered prop for prop aircraft

Question 7

Minimum control speed during approach and landing Vmcl

Answer 7

• Go-around power or thrust on operating engine
• Most unfavourable Cg position
• Trimmed for approach
• Unfavourable mass
• most critical config. For approach and landing

Minimum roll requirement - 20’ in direction away from inoperative engine in no more than 5 seconds

Question 8

Minimum control speed on the ground Vmcg

Answer 8

Vmcg>Vmca

Without deviating laterally 30’ from runway

• Max available TO thrust / power on operating engine
• Most unfavourable CG Position
• Trimmed for TO
• Unfavourable mass
• most critical TO config.

Must be able to control using rudder alone

Question 9

Influence of Air density on Minimum Control Speed s

Answer 9

Calculated minimum control speeds will be faster in cold, low altitude conditions