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AVIA 204 - FM2B > Advanced Theory of Flight > Flashcards

Advanced Theory of Flight Flashcards

1
Q

Bigger Planes

A
  • Increased momentum, stable approach essential, not as maneuverable, need good power management
  • Larger weight and C of G range
  • Long wheelbase
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2
Q

Faster Planes

A
  • Requirement for low drag in cruise to maximize speed and minimize fuel consumption
  • Decreased Drag results in decreased lift
  • Power assisted controls to ease pilot workload (hydraulic, fly-by-wire)
  • Better care required
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3
Q

Higher Planes

A
  • Decreased air density, so lower drag, better fuel efficiency
  • Jet engines are more efficient at higher altitudes
  • TAS increases about 2% per 1000 ft
  • No weather, little turbulence
  • Unstable Environment
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4
Q

Multi Engine Theory

A
  • Safer than single engine planes
  • Plane loses 50% of thrust with an engine failure, as well as 80% of excess thrust
  • Excess thrust allows plane to climb and accelerate
  • Obstacle clearance will become an issue depending on density altitude and terrain
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5
Q

Graph

A
  • Required Thrust vs Thrust available
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6
Q

Single Engine Service Ceiling

A

At Vyse, rate of climb decreases to 50 fpm

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7
Q

Single Engine Absolute Ceiling

A
  • Maximum altitude attainable
  • Vyse and Vxse are equal
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8
Q

Engine Failure - Pitch

A
  • Air flow over the horizontal stabilizer reduced
  • Negative lift reduced, nose will pitch down
  • Must pull back on yoke to maintain altitude
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9
Q

Engine Failure - Roll

A
  • Propellers push airflow over wings, causing lift in addition to the forward motion of the aircraft
  • Aircraft will roll toward dead engine
  • Not applicable to jets
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10
Q

Engine Failure - Yaw

A

Aircraft will yaw toward the dead engine since the operating engine is offset from the centre line of the aircraft

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11
Q

Engine Failure - Sideslip Condition

A
  • Due to yaw force, ball will not be centered
  • If use opposite rudder to centre ball, you end up flying sideways, with a LOT of form drag
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12
Q

Engine Failure - Zero Sideslip

A
  • To eliminate the form drag, we bank 2-5 degrees into the operating engine
  • The horizontal component of lift applies counter yaw
  • “Split” the ball into the good engine
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13
Q

Engine Failure - Drag Factors

A
  • Zero sideslip
  • Full flaps (400 fpm)
  • Windmilling prop (400 fpm)
  • Extended Gear (100 fpm)
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14
Q

Engine Failure - Vital Actions

A
  • Control the aircraft
  • Max power on good engine
  • Clean up drag
  • Dead foot, dead engine
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15
Q

Minimum Controllable Airspeed (Vmc)

A
  • As nose pitches up we get more yaw
  • Eventually we will run out of opposite rudder travel
  • Aircraft will then yaw uncontrollably
  • Recover by reducing angle of attack and reducing power
  • Could lose 1000’ in recovery
  • Try to maintain “blue line” Vyse if trying to climb
  • Vmc is shown as a “red line” on the airspeed indicator
  • Vmc (IAS) will decrease with an increase in altitude
  • Normally hit Vmc before Vs, but if we increase altitude, will hit stall speed first
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16
Q

Engine Failure - Vs (IAS)

A
  • Will stay the same with an increase in altitude
  • Altimeter readings and lift stay proportional
17
Q

How Vmc is determined - Conditions

A

Increase in altitude or temperature lowers Vmc

18
Q

How Vmc is determined - Power Setting

A
  • Reduction in power would lower Vmc
  • More power, more yaw
19
Q

How Vmc is determined - Critical Engine Windmilling

A

Feathering reduces Vmc
- If feathered, rudder is more effective at counteracting drag

20
Q

How Vmc is determined - Flaps and Gear

A
  • Both reduce Vmc
  • Gear acts like a rudder
  • Flaps stabilize the aircraft
21
Q

How Vmc is determined - C of G

A

Moving the C of G forward would reduce Vmc

22
Q

How Vmc is determined - Bank

A
  • Up to 5 degrees of bank (zero sideslip) reduces work load on rudder
  • Vmc reduced 3 KIAS for each degree of bank
  • Moire than 5 degrees of bank would reduce the total lift on the wings significantly
23
Q

How Vmc is determined - Weight

A

Vmc will decrease with a heavier plane

24
Q

How Vmc is determined - Critcial Engine

A
  • One that is shutdown or failed
  • If non-critical engine fails, Vmc is also reduced
25
Q

Critical Engines - PAST

A
  • P-Factor
  • Accelerated Slipstream
  • Spiralling Slipstream
  • Torque
26
Q

Critical Engines - P-Factor

A
  • Also called asymmetric thrust
  • Down going blade produces more thrust than up going blade
  • Difference becomes greater when nose is pitched up
  • If left engine fails, left engine is critical
27
Q

Critical Engines - Accelerated Slipstream

A
  • P-Factor causes more air to be accelerated back over the wing behind the down going blade
  • Causes more lift and more roll
  • Left engine fails, left engine critical
28
Q

Critical Engines - Spiraling Slipstream

A
  • Airflow corkscrews off of the prop
  • If right engine quit, aircraft would become more controllable
  • If left engine quit, no benefit
  • Left engine critical
29
Q

Critical Engines - Torque

A
  • Aircraft want to roll opposite to propeller
  • If right engine quits, aircraft would roll right, but counteracted by left engine trying to roll the aircraft left
  • If left engine quits, aircraft wants to roll left, increased by torque from right engine
  • Left engine is critical
30
Q

Solution to Critical Engines

A
  • Counter rotating propellers
  • Piper Seminole has this
  • Turbines have no critical engine
31
Q

Area Rule

A
  • In order to control form drag, cross section of an aircraft must change very gradually, known as area rule
  • Sears-Haack body is “perfect” aerodynamic shape
32
Q

High Speed Theory

A
  • As an object approaches the speed of sound, the air gently speeds up
  • When it decelerates, it does so quickly and a shockwave forms
  • The disturbed airflow causes vibration and potential damage to an airplane
  • Air moving over a wing can reach transonic speeds if airliner is travelling well below mach 1 due to Bernoulli’s principle
33
Q

Shockwave

A
  • speed is Mcrit (critical mach number), speed at which shockwave first appears
  • Beyond Mcrit, the shockwave forms
  • The faster the plane’s speed, the farther back the shockwave moves along the wing
  • Can sometimes see the shockwave on an airliner wing as a shallow ridge of saturated air
  • Farther back the shockwave, farther back the C of P
  • On large aircraft with long chord, C of P can move well behind C of G
  • Farther back the shockwave, the more turbulent the airflow after the shockwave
34
Q

Temperature, Pressure, and Air Density Over Wing At Transonic Speeds

A
  • All slowly increase in the supersonic flow until the shockwave, where they decrease rapidly
  • This decrease in pressure also causes extra lift
35
Q

Mach Tuck

A
  • Turbulent downwash reduces the effectiveness of the elevators to control the pitch
  • Nose of the aircraft lowers and becomes very unstable
  • Other result is a buffet on the airframe known as High Speed Mach Buffet
36
Q

Mach Buffet

A
  • Can only fly fast aircraft to the point where there is little supersonic flow over the wing
  • Limited to about Mach 0.6 unless we use a swept wing
37
Q

Swept Wing

A
  • Swept wing “tricks” the air into “thinking” it is going slower than it really is
  • Allows the aircraft to attain speeds in the Mach 0.85 range with experiencing Mach Tuck or high speed buffet
  • Only component of airflow that is parallel with the chord creates lift
  • As long as this component is kept below Mcrit, total airflow can greatly exceed the limiting mach number
  • Wingtip will stall first unless washout is used
38
Q

Swept Wing Drawbacks

A
  • Less lift on the wing
  • Needs to fly faster than if it had a straight wing
  • Usually have high lift devices for low speed operations
  • At high angles of attack and high speeds, the wing could have a “low speed buffet”
39
Q

Angle of Attack

A
  • As AOA increases, distance the air over the top surface must travel increases
  • Airflow speeds up with the low pressure and may reach Mcrit at a lower than normal speed due to the increase in the AOA

AVIA 204 - FM2B (10 decks)

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