Theory of Flight Flashcards
Provide an example of inertia
(1) Requires more torque to accelerate to 100% RPM than to maintain 100% RPM.
(2) Straight and level flight.
Provide an example of acceleration
(1) Rate of acceleration to 100% RPM from Engine Idle dependent upon amount of force applied through introduction of fuel and oxygen.
(2) Power required to accelerate heavy A/C versus light A/C.
Provide an example of action/reaction
Torque effect. Main rotor turns counterclockwise forcing nose of helicopter to turn clockwise. T/R thrust is used to compensate for this action.
Main rotors left, nose yaws right
Newton’s First Law
First law–inertia. Definition. A body at rest will remain at rest, and a body in motion will remain in motion at the same speed and in the same direction unless acted upon by some external force.
Newton’s Second Law
Second law–acceleration. A change in velocity with respect to time. A=F/M (Acceleration = Force/Mass)
Newton’s Third Law
Third law–action and reaction.
(a) Definition. For every action, there is an equal and opposite reaction.
How is chord measured? What can be determined from this?
The chord is measured from the leading edge to trailing edge of the airfoil. It provides longitudinal dimension and is self contained in the airfoil section
Why is center of pressure important?
the most important part of the air foil because all aerodynamic forces are considered to act
With an increase in speed of air over a surface what happens to dynamic pressure?
Higher dynamic pressure
What happens to static pressure?
With an increase in the speed of air over a surface, there will be a decrease in static pressure; conversely, with a decrease in speed, there will be an increase in static pressure.
What kind of lower camber does a nonsymmetrical airfoil have?
lower straight camber
What are the advantages of a symmetrical airfoil?
constant center of pressure
ease of construction
lower cost
Chord Line
It is an imaginary line which extends through the leading edge of which all angles and winds are measured
Blade Span
physical measurement of one blade from root to tip
Define resultant relative wind.
Rotational relative wind modified by induced flow.
Define angle of incidence.
What control moves it?
The angle between the chord of an airfoil and the plane of rotation (tip path plane.
It is a mechanical angle rather than an aerodynamic angle.
Collective
Which control changes the angle of incidence on all blades simultaneously?
Angle of incidence is changed on all blades simultaneously by collective pitch control.
Define angle of attack.
The angle between the chord of an airfoil and the resultant relative wind. Angle of Attack is an aerodynamic angle.
Can the angle of attack change with no change in angle of incidence?
Yes
How is angle of incidence measured?
from the chord line to the rotational relative wind
How is angle of attack measured?
from the chord line to the resultant relative wind
What is the relationship of lift to resultant relative wind?
Perpendicular to the resultant relative wind.
What is the relationship of drag to resultant relative wind?
Parallel to and in the same direction of the resultant relative wind.
What are the 4 types of drag?
Induced, Profile, Parasite, Total