PHAK CH 5 (Aerodynamics Of Flight) Flashcards
In Unaccelerated Level Flight the Four Forces Are?
Thrust Equals Drag and Lift Equals Weight
The sum of all forward forces equals the sum of all backwards forces
The sum of all upward forces equals the sum of all downwards forces
Anytime a Flight Path is Not Horizontal….
Lift, weight, thrust, and drag vectors must each be broken down into two components.
Lift provided by the wing or rotor is the primary lifting force
Weight is the primary downward force.
Angle of Attack (AOA)
The angle at which the chord line of the aircraft’s wing meets the relative wind.
The Three Speed Regimes of Flight
Low Speed Flight, Cruising Flight, and High Speed Flight
Critical Angle of Attack (AOA)
If speed is decreased enough that the AOA has to be increased, in an attempt to create a lifting force that balances out the weight of the aircraft, the AOA can be increased too much and boarders into the critical AOA.
The Critical AOA: is the angle at which the wing/plane is over pitched and can no longer gather proper airflow, for lift to balance out the weight if the aircraft, Lift begins to diminish rapidly
Extra Vigilance is required at reduced thrust settings and low speeds, so as not to exceed the critical angle of attack.
CL max Critical AOA
When the aircraft reaches the maximum AOA, lift begins to diminish rapidly. This is the stalling AOA.
CL increases until the critical AOA is reached, the decreases rapidly with any further increase in the AOA.
The Shape of the Wing or Rotor cannot be Effective unless….?
If continuously keeps “attacking” new air, if an aircraft is to keep flying it, the lift producing airfoil must keep moving across the lifting surface.
Lift is Proportional to?
The square of the aircraft’s velocity. Thus velocity is an important component of lift, which can be affected through varying AOA.
Parasite Drag
DOES NOT ASSIST IN FLIGHT, IS A PARASITE
All of the Forces that Work to Slow an Aircraft’s Movement.
Form Drag, Skin Friction Drag and Interference Drag
Form Drag
THINK FORM= SHAPE OF PLANE
Due to the aircrafts FORM/shape and the airflow around it.
Examples include: antennas, engine cowlings, wings
Interference Drag
Nooks and Crannies, LITTLE STUFF
Intersections of airstreams, that create eddy currents, turbulence, or restricts smooth airflow.
Pilot Tube, FUSELAGE CONNECTED AT THE WING ROOT
Skin Friction Drag
MICROSCOPIC FRICTION
Is the aerodynamic friction due to the contact of moving air with the surface of an aircraft.
Screws, tiny stuff, Keeping surfaces of the aircraft clean and free of dirt
Induced Drag
INDUCED CREATED BY IT
Is drag that is a by product of lift
Wing Tip Vortices
The rotational flow of air at the tips of an aircrafts wing tips due to pressure equalization and lateral flow from the underside to the upper surface. (IS NOT BLOCKED BY THE FUSELAGE, SPILLAGE OF AIR OFF OF THE FUSELAGE, path of Least Resistance)
FROM THE TAIL: the vortices circulate counterclockwise about the right tip and clockwise off the left tip. OUT (from under plane), UP and AROUND.
WORSE FROM AIRCRAFT THAT ARE HEAVY, CLEAN, and SLOW
Downwash
As the wing tip vortices roll off the back of the wing, they angle down, which is known as downwash.
IT IS THE SOURCE OF INDUCED DRAG
More downwash more induced drag
More Induced Drag in the Air
Less Induced Drag Closer to the Ground
Aircraft create maximum wingtip vortices with max strength occurring during the takeoff, climb, and landing phases of flight.
Induced Drag is worse at?
Lower Speeds, Increased AOA (this creates greater flow of air under the wing = more violent air vortices)
Parasite Drag is Worse at?
Higher Airspeed
The Center of Gravity must be where?
CG is has a great bearing on the stability of the Plane
Forward of the Center of Lift (CP) for equilibrium
Avoiding Wake Turbulence
Stay Over, and Above their Flight Path
Allow Roughly 3 minutes of Separation for Wake Turbulence to Disperse
Rotate prior to their Rotation Point
Avoid Flying in or Below their Path (1,000ft)
Touch Down after the Point the Aircraft’s Touchdown Point
Wake Turbulence can be Affected by Wind How?
Wake Turbulence can drift with the wing at the speed of the wind.
Ground Effect
Ground effect is due to the interference of the ground (or water) surface with the airflow patterns about the aircraft in flight; because the vertical component of the airflow around the wind is restricted by the surface. This alter’s the wings updrafts, downwash and wingtip vortices.
Air that is trapped between the wing and the landing surface is called ground effect. HELPFUL HAND/AIR CUSHION
**ONLY when the Wing Is CLOSE to the GROUND, LESS Than the Wing Span **
Ground Effect During Takeoff
Ground Effect causes an increase in the local pressure at the static source and produces a lower indication of airspeed and altitude. Aircraft may seem like it can become airborne at a speed well below take off speed, due to the reduction in drag, in some cases the aircraft could take off and then fall back down again
Aircraft Leaving Ground Effect Might Experience:
Require an Increase in AOA to maintain the CL
Experience and increase in Induced Drag and Thrust Required
Experience a Decrease in Stability and a Nose-Up Change in Moment
Experience a Reduction in Static Source Pressure and Increased in Indicated Airspeed
Floating
Caused by excess speed at the point of flare, Because of the increase in lift from ground effect.
3 Axis’ of the Plan
(How, What, and Control)
Longitudinal: rolling ailerons
Lateral: pitch elevator
Vertical: yaw rudder
3 Axis’ of the Plan
(How, What, and Control)
Longitudinal: rolling ailerons
Lateral: pitch elevator
Vertical: yaw rudder
