NIFE Aerodynamics 2-4-1 Maneuvering and Hazards Flashcards
Describe a slip
Caused by opposite or insufficient rudder in the desired direction of turn. The yaw moment is to the outside of the turn. If a stall occurs, the wings will roll to level.
When can a slip be used
Good for crosswind landings or when trying to increase rate of descent without increasing speed
Describe a skid
Caused by using too much rudder in the desired direction of the turn. Yaw moment toward inside of turn. Plane will roll inverted if a stall occurs
Describe the effects of low speed P-factor
The yawing moment caused by one prop blade creating more thrust than the other. The down-going blade will create more thrust, causing a yaw in the opposite direction.
Two requirements for P-factor to have a noticeable effect
- Engine must be at high power
2. The thrust axis must be displaced from the relative wind
When will P-factor be most noticeable
At AOAs significantly different from cruise AOA, such as high AOA climbs
Describe the effects of slipstream swirl
The corkscrewing motion of the air will flow around the fuselage until it hits the vertical stabilizer where it increases the AOA on the stabilizer, causing a leftward yaw.
When will slipstream swirl be most noticeable
At a high power setting and a low airspeed
How to compensate for slipstream swirl
Right rudder and lateral control stick inputs
Define load factor
Ratio of the total lift to an airplane’s weight, also called G’s
Describe the relationship between load factor and angle of bank for a level constant speed turn
In a turn, the lift vector is divided into a horizontal and vertical component. Total lift is equal to total weight in level flight, but in a turn, only the vertical component of the lift vector opposes weight. The AOA must be increased to increase lift.
Define limit load factor
The greatest load factor an airplane can sustain without any risk of permanent deformation.
Define ultimate load factor
The maximum load factor that the airplane can withstand without structural failure. Some permanent deformation may occur but failure will not occur
Overstress/Over-G
The condition of possible permanent deformation or damage that results from exceeding the limit load factor. Damage that maybe done to equipment mounted in the airframe due to the wing being overstressed. Always report to maintenance
Define elastic limit
The maximum load that may be applied to a component without permanent deformation
Describe the boundaries of the safe flight envelope
Within:
- Accelerated stall lines
- Pos and neg limit load factors
- Pos and neg ultimate load factors
- Redline airspeed (Vne)
Accelerated stall lines
(aka, lines of max lift) Represent the max load factor that an airplane can produce based on airspeed.
What determines accelerated stall lines
CLmax AOA
Why are most maneuvers performed with positive accelerations
Pilots cannot sustain a negative acceleration much greater than three G’s. Therefore, designers can save some weight by reducing the plane’s ability to sustain negative G’s
Define maneuver point
The point where the accelerated stall line and the limit load factor line intersect.
What is the IAS at the maneuver point called
Maneuver speed (Va). Also called cornering velocity
Define maneuvering speed/cornering velocity
The lowest airspeed at which the limit load factor can be reached.
What is significant about the maneuver speed
Below it, we can never exceed the limit load factor because the plane will stall before it is reached
Redline airspeed (Vne)
The highest airspeed that an airplane is allowed to fly without causing structural damage
What determines Vne
- MCRIT (critical mach number)
- Airframe temp
- Excessive structural loads
- Control ability limits
Describe wake turbulence
Wingtip vortices are spiraling masses of air that are formed at the wingtip when an airplane produces lift and continue aft. This disturbance is often called “jet wash” or “wake turbulence”. Strength is directly related to induced drag
Characteristics that increase wake turbulence
- weight
- speed
- wing shape
(aka, heavy, slow, and clean)
Wake turbulence characteristics
- All planes produce a vortex hazard
- Not generated until the nosewheel leaves or touches the ground
- Lowering flaps will help decrease vortices
- Sink at 400-500 fpm
- Level off about 900’ below flight path
Hazards of wake turbulence
Loss of control due to induced roll
Describe procedures to avoid wake turbulence
- Cereal bowl
- 2 minute interval
Define wind shear
A sudden change in wind direction and/or speed over a short distance in the atmosphere.
Describe how wind shear can be a hazard during landing
As airflow changes, so does dynamic pressure over the wing, affecting lift. Do not make aggressive corrections
