03-10-2016, 01:01 PM
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Aerodynamics
A study guide on aerodynamics for the Piper Archer
Aerodynamics
The purpose of this pilot briefing is to discuss the simple and complex aerodynamics of the Piper Archer.
Please use the following references:
Pilot’s Handbook of Aeronautical Knowledge
Flight Theory for Pilots
Aerodynamics-Basics
These fundamental basics first must be acknowledged:
Air is a fluid. It can be compressed & expanded
The atmosphere is composed of
78% nitrogen
21% oxygen
1% other gasses
Most of the oxygen is below 35,000 feet. (WHY?)
Aerodynamics-Basics
Newton’s Laws of motion:
Law 1 – A body at rest will remain at rest. A body in motion will remain in motion
Law 2 – F=MA Force is equal to mass times acceleration
Law 3 – For ever action there is an equal and opposite reaction
Aerodynamics-Basics
Bernoulli’s principle:
Aerodynamics-Basics
Because air is a fluid, it utilizes the properties of the Coanda effect: the tendency for a fluid to follow the object along its flow path.
Aerodynamics - Stalls
When does an airplane stall?
When it exceeds the critical angle of attack.
Aerodynamic-Stalls
Stall speed vs. Ground speed
An airplane will stall at the respected Indicated airspeed. It does NOT matter what the groundspeed is!
If you have a stiff enough headwind at altitude, on a given day, you can stall an airplane with a negative groundspeed.
Indicated airspeed is the speed read directly from the airspeed indicator; it is the speed the plane thinks it is at.
Groundspeed is the speed of travel over the ground. There is minimal correlation with indicated airspeed; because groundspeed is dependent upon outside wind velocities.
Aerodynamics-Stalls
A stall occurs first at the wing root, then works out toward the tip. This design characteristic is so that you still maintain aileron control as long as possible.
Stall speed refers to straight and level, 1G, unaccelerated flight. Regardless of airspeed, the plane will ALWAYS stall when the critical angle of attack is exceeded.