A103 Aerodynamics Flashcards
Where is the center of gravity?
Origin for lateral (pitch), lognitudinal (roll), and vertical (yaw) axis
What is the angle of attack?
The angle between the relative wind and the chord line
What causes a stall?
When the critical angle of attack is exceeded, and lift can no longer be generated
What causes lift?
- Bernoulli’s Principle increased velocity over the curved upper side of the wing causes increased velocity and low pressure, lower velocity higher pressure air flows under the wing
- Newton’s Third law
As air is deflected downward by the wing the wing is deflected upward
What are the types of Parasitic Drag
- Form drag
- Interference drag
- Skin friction drag
What is form drag?
- Parasite drag from turbulent wake caused by airflow around a structure
- Depends on size and shape of structure
What is Interference Drag?
- Parasite drag from interaction of varied currents that flow over an airplane and mix together
What is Skin Friction Drag?
- Parasite drag from roughness of airplane
surfaces - Rivet heads
- Irregularities (bugs / dirt)
What is Induced Drag?
- Drag created by the
production of lift - Inversely proportional
to square of the speed * Half airspeed = Four
times induced drag - Predominant at low
airspeeds (high AOA)
What causes turning flight?
- Horizontal component of lift
causes airplane to turn - When vertical component of
lift equals weight aircraft will
neither gain nor lose altitude
What is ground effect, when is it strongest, and are high or low wing planes affected more?
- Phenomenon of less induced drag close to ground
- Earth’s surface alters airflow patterns around aircraft
reducing downward deflection of airstream - At height equal to wingspan and lower
- More noticeable on low wing aircraft as wing gets close to
ground during takeoff and landing
What is critical angle of attack?
The point where the coefficient of lift is maximum is CL Max
What causes a spin?
- Combination of Stall & Yaw
- Uncoordinated stall resulting in a descending
corkscrew path - One wing more stalled than other
- Will spin in same direction as yaw
What is adverse yaw and how do we account for it?
- While rolling into a turn, outside wing produces more lift
- Induced drag increases on outside wing
- The increased induced drag causes yaw opposite of the direction of the roll
- Use rudder in the direction of the roll in coordination with ailerons to compensate for adverse yaw
What is load factor?
Ratio of:
Load supported by the wings
to
Actual weight of the aircraft and contents
Increasing load factor will
cause an airplane to stall at
a higher speed
