Aerodynamics U-28 Flashcards
What are the four left-turning tendencies
Torque reaction
Corkscrew effect
Gyroscopic action
Asymmetric loading (P-factor)
Describe Torque Reaction
The torque from the clockwise (right) propeller spinning (force) generates an opposite left rolling moment on the airframe.
Describe Corkscrew Effect
The propeller’s spiraling slipstream (force) generates a left yawing moment and a less prominent right rolling moment.
Describe Gyroscopic Action
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.
Describe (P-factor) Asymmetric Loading
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.
What is the T-tail for
In normal conditions moves elevators upward into air undisturbed by propwash or wing surfaces…provides consistency throughout many flight regimes.
What is the most dangerous flight regime for the T-tail
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.
What are the Winglets for
Winglets reduce wingtip vortices/induced drag by blocking some of the low pressure air spilling over the wingtip.
What on the U-28 reduces adverse yaw
Dorsal fin
Ventral strakes
What are the benefits of fowler flaps
Primary advantage is the increase in both WING AREA and CAMBER.
What are the 3 factors of stall
Aircraft weight
Flap setting
Bank angle
What stall factor increases LINEARLY
increasing weight
What stall factor increases EXPONENTIALLY
increasing bank angle
What flap settings results in a significant decrease in stall speeds and why
0 to 15 flaps; Because this movement increases wing area (and lift) more than it increases camber (and drag)
What does raising flaps do during a stall recovery
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
Define Vs
Stall speed: minimum steady-state controllable speed
Define Vr
Rotation speed: Normally Vs1 for single-engine aircraft
Define Vref
Landing reference speed: 1.3(Vs)
Define Vmo
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
What are the flaps up G limits for acft weight less 10450 lb
+3.3 g to -1.32 g
What are the flaps up G limits for acft weight more than 10450 lb
+2.5 g to -1.0 g
What are the flaps extended G limits
+2.0 g to 0.0 g
What are the balance of forces for level flight
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).
What are the three types of structural loading
Bending moment
Shearing force
Torsion moment
Describe bending moment
The moment created by a transverse deflection of a body through and perpendicular to its longitudinal axis
-fat guy walking on a plank
Describe shearing force
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
Describe torsion moment
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
What bank angle and greater is prohibited for the U-28
60 degrees or more
What maneuvers are prohibited for the U-28
Aerobatic maneuvers, including spins
What FAA category is the U-28 certified in?
The NORMAL category
