OEI Aerodynamics

Question 1

Biggest difference in Single to Multi

Answer 1

Managing OEI

requires understanding OEI aerodynamics

Question 2

OEI Problems

Answer 2

Control

Performance

Sideslip

Question 3

Control Problem - Draw and Explain

Answer 3

YAW toward inop engine
- less thrust
- drag from windmilling prop
ROLL toward inop engine
- asymmetry of induced lift / accelerated slipstream
PITCH down
- loss of slipstream to stabilizer
- loss of induced lift

Question 4

Control Problem - explain how to manage

Answer 4

*counteract with aileron and rudder
*Vmc airflow for rudder

< Vmc inadequate airflow to counteract = loss on control
> Vmc possible to control

Vmc is variable.

Question 5

Performance Problem - draw and explain

Answer 5

Four Forces of Flight:

Lose 50% THRUST; lose 80-90% performance.

• LIFT (50-60% lift is induced from accel slipstream)

+ DRAG
+ induced - higher AoA
+ propeller windmilling

Question 6

Performance Problem - How to Manage

Answer 6

OEI - may have insufficient performance to maintain level flight.

Plan ahead.
- know A/S and A/G vs know what’s beyond end of runway.
- know SE climb performance vs terrain/req gradients.
- know SE Service ceiling vs elevation of terrain.

Question 7

Sideslip Problem - draw and explain

Answer 7

SE Thrust + Rudder force = Result vector

Sideslip
- more drag (bad for performance)
- less rudder effectiveness (bad for directional control / Vmc)

Question 8

Sideslip Problem - how to manage

Answer 8

Counter sideslip by
- banking 2-3° (5-10° initially) toward OE
- ball split half toward OE

Banking toward OE creates a lateral component of weight that cancels the rudder force (see picture).

• more weight = better for control; less performance

Question 9

Critical Engine PAST - draw and explain

Answer 9

Conventional twin engines rotate CW CW

P-factor

Accelerated slipstream

Spiral slipstream

Torque

Counter-rotating engines CW CCW, equally critical