Multiengine Aerodynamics Flashcards

1
Q

S.M.A.C.F.U.M.

A

S - Standard Day
M - Most Unfavorable Weight (light)
A - Aft CG
C - Critical Engine Windmilling
F - Flaps Up, Gear Up, Trim T/O
U - Up to 5° of Bank
M - Max Power

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2
Q

S - Standard Day

A
  • Increased Performance
  • Decreased Control
  • Increased Vmc
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3
Q

M - Most Unfavorable Weight (Light)

A
  • Increased Performance
  • Decreased Control
  • Increased Vmc
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4
Q

A - Aft CG

A
  • Increased Performance
  • Decreased Control
  • Increased Vmc
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5
Q

C - Critical Engine Windmilling

A

A windmilling propeller creates more drag and, therefore, stronger yaw moment

  • Decreased Performance
  • Decreased Control
  • Increased Vmc
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6
Q

F - Flaps Up, Gear Up, Trim T/O

A

Flaps increase drag near the fuselage which stabilizes the a/c
Landing gear increases keel effect which stabilizes the a/c
With both retracted, the a/c is less stable and better performing

  • Increased Performance
  • Decreased Control
  • Increased Vmc
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7
Q

U - Up to 5° of Bank

A

This is actually a benefit

With wings level and ball centered, the a/c is in mild side-slip - decreased performance, increased drag

With 5° of Bank and ball centered, the a/c is in zero side-slip - increased performance, decreased drag

Even though performance increases, control also increases

  • Increased Performance
  • Increased Control
  • Decreased Vmc
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8
Q

M - Max Power

A
  • Increased Performance
  • Decreased Control
  • Increased Vmc
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9
Q

Vmc Certification Requirements

A
  • No less than 1.2xVs1
  • Most unfavorable Weight (light)
  • Up to 5° of Bank
  • <= 150 lbs rudder force
  • <= 20° change in heading
  • T/O config (flaps up, gear up, trim t/o, prop t/o)
  • Critical engine inoperative

For A/C <6,000 lbs., add landing config (flaps ldg, gear down)

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10
Q

Critical Engine

A

The engine that, when inoperative, has the most drastic effect on airplane control

In conventional twins, always left engine

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11
Q

Determining Critical Engine

A

P.A.S.T

P - P-Factor (thrust-line to mid-line of a/c)
A - Accelerated Slip-Stream (more lift closer to fuselage)
S - Spiraling Slip-Stream
T - Torque Effect

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12
Q

How is climb rate affected when operating on 1 engine?

A

A/C loses about 80% of climb rate

varies with specific models, but always >50%

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13
Q

What is Vmc?

A

The airspeed at which the a/c will lose directional control - “run out of rudder”

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14
Q

What is Critical Density Altitude (CDA)?

A

The altitude at which Vmc = Vs

Above CDA, a/c will stall first
Below CDA, a/c will yaw first

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15
Q

How is Vmc indicated?

A

By a red radial line on the airspeed indicator

Be aware, Vmc is a calibrated airspeed!

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