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21 Cards in this Set
- Front
- Back
- 3rd side (hint)
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How much performance is lost in a twin with 1 engine inoperative? Why?
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With 2 engines of 200hp and it requires approximately 160hp to fly straight and level at L/D max:
-Therefore; The excess hp available to climb = (2 x 200) -160 = 400-160 = 240hp With the Loss of one Engine -Excess hp available to climb = (1 x 200)-160 = 40hp The loss of performance is : 240hp–40hp = 200hp % loss = (200/240) x 10 = 83% |
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Define 'Absolute Ceiling'.
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With both engines at max power, no further climb is possible.
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Define 'Service Ceiling'.
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With both engines at max power, a climb rate of 100fpm can be maintained.
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Define 'Single Engine Absolute Ceiling'.
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With one engine feathered, no further climb is possible.
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Define 'Single Engine Service Ceiling'.
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With one engine feather, a climb rate of 50fpm can be maintained.
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Define 'Critical Engine'.
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The engine whose failure would most adversely effect the performance and handling characteristics of the aircraft.
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Define 'Vmc'.
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-Vmc is the minimum airspeed at which direction control may be maintained with the critical engine inop.
-The rudder no longer has the authority to overcome the adverse yaw caused by the critical engine being inoperative, under specific criteria. |
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Define 'Sideslip Condition'.
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The sideslip condition is where the adverse yaw and roll created by an inoperative engine is compensated by use of the rudder while the aircraft wings are kept level with reference to the horizon. This will enable the pilot to maintain heading, however it will produce much drag as the relative wind will be hitting the side of the plane. This will cause a significant degradation in performance and an increase in Vmc.
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Define 'Zero Sideslip Condition'.
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This is the answer to maintaining aircraft heading while minimizing drag. It involves using a horizontal component of lift to assist overcoming the turning moment brought by the operative engine. This is done by banking the aircraft 2-5degrees into the operative engine. This reduces the amount of rudder required and aligns the aircraft to the relative wind. The amount of rudder required is indicated by splitting the inclinometer ball in half towards the operating engine.
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How is Vmc indicated on the airspeed indicated?
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It is the red line.
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How is Vyse indicated on the airspeed indicator?
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It is the blue line.
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What makes a critical engine critical?
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P-factor
A-ccelerated slipstream S-prialing slipstream T-orque |
PAST
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Which is the critical engine on the DA42?
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The LH engine.
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Explain why P-factor contributes to the engine being critical.
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This is caused by the down blades of a propeller having a greater angle of attack then the up blades when an aircraft is flying at an angle to the relative wind (as in climbing or slow flight). This causes more thrust on the down going side of the propeller which is on the right side.
Therefore, the right engine on a conventional twin will have a trust line further from the center of the aircraft than the left engine. Hence, loosing the left engine would be more critical then losing the right. |
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Explain why accelerated slipstream contributes to the engine being critical.
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P factor causes the induced slipstream (accelerated slipstream) to be further outboard on the right wing and inboard on the left. Thus, loosing the left engine would cause the remaining induced slipstream (on the right wing) to be further outboard than would be the case if you lost the right engine. This would cause a greater rolling tendency towards the dead engine.
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Explain why spiraling slipstream contributes to the engine being critical.
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The corkscrew vortex of air induced by the propellers acting on the aircraft vertical stabilizer causes the aircraft to yaw to the left (this is normally trimmed out in airframe design). This effect counters the adverse yaw of a right engine failure but compounds that of a left one.
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Explain why torque contributes to the engine being critical.
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For every action there is an equal but opposite reaction. A propeller spinning to the right will induce a reaction in the aircraft to the left. Once again this effect counters the adverse yaw of a right engine failure but compounds that of a left one.
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What are the criteria for Vmc?
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-Maximum take off power
-Critical engine inoperative -Inoperative engine windmilling -5 degrees of bank into the operative engine -Most adverse legal weight -Most adverse legal C of G -Gear up -Flaps takeoff position -Cowl flaps open -Sea Level Conditions -Out of ground effect |
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What happens to Vmc as altitude increases?
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It decreases.
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What happens to the stall speed as altitude increases?
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It stays the same.
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What is the danger of doing a Vmc demo at a high density altitude?
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A point may be reached when Vmc and stall speed are equal, this is known as coffin corner because a spin may be induced if the aircraft yaws (as in a Vmc demo) and stalls as the same time. You never spin a twin.
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