Aerodynamics U-28

Question 1

What are the four left-turning tendencies

Answer 1

Torque reaction
Corkscrew effect
Gyroscopic action
Asymmetric loading (P-factor)

Question 2

Describe Torque Reaction

Answer 2

The torque from the clockwise (right) propeller spinning (force) generates an opposite left rolling moment on the airframe.

Question 3

Describe Corkscrew Effect

Answer 3

The propeller’s spiraling slipstream (force) generates a left yawing moment and a less prominent right rolling moment.

Question 4

Describe Gyroscopic Action

Answer 4

Action of a spinning rotor (force) can generate a yawing moment or a pitching moment, depending on where the initiating force is applied. When aircraft pitch is increased a left yawing force is created.

Question 5

Describe (P-factor) Asymmetric Loading

Answer 5

When aircraft pitch is increased, the descending (right) blade has a higher AOA than the ascending (left) blade and is generating more thrust . This thrust imbalance generates a left yawing moment.

Question 6

What is the T-tail for

Answer 6

In normal conditions moves elevators upward into air undisturbed by propwash or wing surfaces…provides consistency throughout many flight regimes.

Question 7

What is the most dangerous flight regime for the T-tail

Answer 7

High AOA, low speed, with aft Center Gravity.

• Airflow across the T-tail is less ‘clean’ at higher AOA.
• Low speeds and aft CG both increase the control deflection required to achieve the same effect.
• Causes a deep stall, and tail stalls after the wing.

Question 8

What are the Winglets for

Answer 8

Winglets reduce wingtip vortices/induced drag by blocking some of the low pressure air spilling over the wingtip.

Question 9

What on the U-28 reduces adverse yaw

Answer 9

Dorsal fin

Ventral strakes

Question 10

What are the benefits of fowler flaps

Answer 10

Primary advantage is the increase in both WING AREA and CAMBER.

Question 11

What are the 3 factors of stall

Answer 11

Aircraft weight
Flap setting
Bank angle

Question 12

What stall factor increases LINEARLY

Answer 12

increasing weight

Question 13

What stall factor increases EXPONENTIALLY

Answer 13

increasing bank angle

Question 14

What flap settings results in a significant decrease in stall speeds and why

Answer 14

0 to 15 flaps; Because this movement increases wing area (and lift) more than it increases camber (and drag)

Question 15

What does raising flaps do during a stall recovery

Answer 15

Raising flaps lowers the wing’s lift coefficient and increases its stall speed, thus increasing the potential sink rate.

DON’T RAISE FLAPS IN A STALL RECOVERY

Question 16

Define Vs

Answer 16

Stall speed: minimum steady-state controllable speed

Question 17

Define Vr

Answer 17

Rotation speed: Normally Vs1 for single-engine aircraft

Question 18

Define Vref

Answer 18

Landing reference speed: 1.3(Vs)

Question 19

Define Vmo

Answer 19

Maximum operating limit speed(maneuvering):
less than 10450 lb: 236 KIAS or 0.48 Mach
More than 10450 lb: 216 KIAS or 0.46 Mach

Question 20

What are the flaps up G limits for acft weight less 10450 lb

Answer 20

+3.3 g to -1.32 g

Question 21

What are the flaps up G limits for acft weight more than 10450 lb

Answer 21

+2.5 g to -1.0 g

Question 22

What are the flaps extended G limits

Answer 22

+2.0 g to 0.0 g

Question 23

What are the balance of forces for level flight

Answer 23

LIFT from the wing moves up, lift from the tail moves down.
WEIGHT (n=1) moves down.
DRAG moves back.
THRUST moves forward.

The wings’ pitching moment moves up and over (pushes nose down)

The Tail’s pitching moment moves down and under (pushes the nose up).

Question 24

What are the three types of structural loading

Answer 24

Bending moment
Shearing force
Torsion moment

Question 25

Describe bending moment

Answer 25

The moment created by a transverse deflection of a body through and perpendicular to its longitudinal axis

-fat guy walking on a plank

Question 26

Describe shearing force

Answer 26

A force tending to cause deformation of a material by slippage along a plane or planes parallel to the imposed stress

-earthquake moving two plates different directions

Question 27

Describe torsion moment

Answer 27

Twisting of a body by the exertion of forces tending to turn one end about a longitudinal axis while the other is held fast or turned in the opposite direction

-wringing a towel

Question 28

What bank angle and greater is prohibited for the U-28

Answer 28

60 degrees or more

Question 29

What maneuvers are prohibited for the U-28

Answer 29

Aerobatic maneuvers, including spins

Question 30

What FAA category is the U-28 certified in?

Answer 30

The NORMAL category