AE 106 Stalls

Question 1

Thin layer of air near surface of airfoil where streamlines demonstrate local retardation due to viscosity

Answer 1

Airfoil Boundary Layer

Question 2

primary producer of lift

Answer 2

laminar flow

Question 3

produces only minimum lift

Answer 3

turbulent flow

Question 4

What are the characteristics of boundary layer airflow from the forward edge to the max point of thickness?

Answer 4

laminar flow, high to low pressure, airflow accelerates, kinetic energy builds, high boundary layer surface adherence

Question 5

What are the airflow characteristics of boundary layer airflow from max point of thickness to trailing edge?

Answer 5

laminar to turbulent flow, low to high pressure, adverse pressure gradient, decreasing boundary layer adherence

Question 6

Caused by low pressure behind max point of thickness

Answer 6

adverse pressure gradient

Question 7

how is adverse pressure gradient controlled?

Answer 7

kinetic energy of the relative wind

Question 8

What is the impact of a high AOA on the boundary layer?

Answer 8

kinetic energy decreases, adverse pressure gradient increases, boundary layer separation point moves forward on the airfoil

Question 9

define boundary layer separation

Answer 9

point in streamline where airflow no longer adheres to the airfoil

Question 10

Where is the point of beginning boundary layer separation?

Answer 10

CL is no longer linear on CL vs. AOA curve

Question 11

Where does a stall occur?

Answer 11

CLMAX

Question 12

Define stall

Answer 12

increase in AOA results in decrease in CL

Question 13

stall ___ remains constant for any given airfoil, and stall ___ is variable based on conditions.

Answer 13

AOA, airspeed

Question 14

for a power-off stall: stall airspeed: ___, stall warning: ___ __ ___, roll tendency: ___ due to engine mounting 1 degree right and 2 degrees down from centerline

Answer 14

higher, closer to stall, right

Question 15

Power-on stall: stall airspeed: ___, stall warning: ___ ___ ___ ___, roll tendency: ___ due to torque effect

Answer 15

lower, further above stall airspeed, left

Question 16

What are the two differences between power-on and power-off stalls?

Answer 16

Vertical component of thrust (increases lift and lowers stall airspeed), propeller acceleration factor (increases airflow rate, lower stall airspeed)

Question 17

What is the order of loss of control effectiveness?

Answer 17

Aileron, Elevator, Rudder

Question 18

What factors affect stall airspeed?

Answer 18

gross weight, altitude (air density), load factor

Question 19

How does weight effect stall speed?

Answer 19

higher weight = higher stall airspeed

Question 20

___ stall airspeed increases with altitude and ___ stall airspeed remains the same

Answer 20

true, indicated

Question 21

A ___ ___ ___ deflects high kinetic energy airflow from bottom of wing to top of wing to suppress boundary layer separation

Answer 21

boundary layer control decive (BLC)

Question 22

What are the benefits of boundary layer control?

Answer 22

increased maneuverability, decreased landing speed and distance

Question 23

power-off stall warning occurs approx ___ knots before stall

Answer 23

3

Question 24

stick shaker provides stall warning ___ to ___ knots before power-off stalls, ___ to ___ units AOA

Answer 24

5 to 10, 15 to 16