Version 1.0, 15 May 2011
Stage 1, Module 1
Copyright © 2011 Ted Dudley
Course and Objectives
Objective: Gain the necessary aeronautical skill, knowledge and experience to meet the requirements of a Private Pilot certificate with an Airplane Category rating and a Single-Engine Land class rating
Four Stages of 5-6 modules each: Stage 1: Introduction to flying Stage 2: Solo Stage 3: Cross-country flight Stage 4: Preparation for checkride
VFA Reqs, Procedures, Regs
Grading Criteria, Expectations
Maneuver Grades 1. Describe (monkey see) 2. Explain 3. Practice 4. Perform (monkey do) 5. Not observed
Stage 1 Objectives -Ground
The student will become proficient in, and have an understanding of: Forces acting on an airplane Stability and control Training airplane (airframe, engine, systems,
flight instruments) Basic flight maneuvers Flight information Flight physiology Regulations
Stage 1 Objectives - Flight
The student will become proficient in, and have an understanding of:
• Flight training process • Training airplane • Preflight • “Special Emphasis Areas” (per PTS) • Taxiing • Four basics of flight (straight and level, turns, climbs, descents) • Use of sectional • Collision avoidance • Slow Flight • Stall series • Steep Turns • Instrument scan
Forces Acting on an Airplane
Weight
The combined load of the airplane and everything in it
Pulls the airplane towards the earth’s center because of gravity
Opposes liftActs vertically downward thru aircraft’s center of
gravity
Lift
Produced by the dynamic effect of air on the wing
Opposes weightActs perpendicular to flight path
Bernoulli’s Principle
Unrestricted tube
Restricted tube
As the velocity of a moving fluid (liquid or gas) increases, the pressure within the fluid decreases
Bernoulli’s Principle
As the velocity of a moving fluid (liquid or gas) increases, the pressure within the fluid decreases
Newton’s Third Law
Bernoulli isn’t all there is to liftFlow over airfoil imparts a downward flow to
air passing over itBy Newton’s Third Law (equal and opposite
reaction), this imparts an upward force on the airfoil
Streamline and Turbulent Flow
(Streamline Flow)
Static Air Pressure
Air exerts a pressure equally in all directions at any point in the atmosphere
This is called static pressureResults from the weight of the air molecules
above that point; it decreases with a gain in altitude
This is what an altimeter measures, usually through the static port(s)
Dynamic Air Pressure
Air has mass (from its molecules); air in motion has dynamic (kinetic) energy which is converted to pressure the moment a body tries to stop it or slow it down
This is called dynamic pressureMeasured by the pitot tube; includes static
pressure at that point, too
Lift and Airspeed
• Lift varies with the square of velocity – double the speed, get 4x lift
Airfoil Shapes
Angle of Attack
The angle between the wing chord line and the relative wind
Aerodynamic Force
As Angle of Attack increases… More lift for a given airspeed Center of pressure moves forward
Drag
A rearward, retarding force caused by disruption of airflow by the wing, fuselage, and other protruding objects
Opposes thrust
Total Drag
Total drag is comprised of…
Parasite drag, which is made up of Form drag Interference drag Skin friction drag
Induced drag
Form Drag
The portion of parasite drag generated by the aircraft due to its shape and airflow around it
Big form dragLittle form drag
Interference Drag
Comes from the intersection of airstreams that creates eddy currents and turbulence, or restricts smooth airflow
Example: the intersection of the wing and the fuselage at the wing root
Significant interference drag
Even more interference drag
Skin Friction Drag
The aerodynamic resistance due to the contact of moving air with the surface of an aircraft
A little skin friction
A lot of skin friction
Induced Drag
The aerodynamic process that makes lift also induces drag, primarily due to generation of wingtip vortices
More lift always means more induced drag; drag is the “price you pay” for lift
The lower the airspeed, the greater the angle of attack (AOA) required to produce lift equal to the aircraft’s weight and, therefore, the greater induced drag
Varies inversely with the square of the airspeed – double the speed, get ¼ the induced drag
Total Drag
Lift/Drag Ratio
The amount of lift generated by a wing or airfoil compared to its drag
Varies with angle of attack; there is one AOA that maximizes L/D for a given wing
Also happens to be the glide ratio – distance traveled divided by altitude lost with no thrust
For your training aircraft, L/D max is around 9
This means you glide 9 feet forward for every foot of altitude; 9 miles forward for every mile of altitude
Lift/Drag Ratio
Decreasing Airspeed
Wing Camber
Camber is a measure of curviness of a wing cross section
More camber generally means more lift
Flaps
Wing flaps effectively increase camber of the wing
Results in increased lift at low speeds and increased drag
Leading Edge Devices
Also increase a wing’s effective camber, lift, and drag
(Also called a slat)
Spoilers
Devices on top of the wing that spoil lift and increase drag
Thrust
The forward force produced by the powerplant/ propeller
Opposes drag
Propeller
Consists of two or more blades and a central hub to which the blades are attached
Each blade is essentially a rotating wingPropeller blades are like airfoils and produce
forces that create the thrust to pull, or push, the aircraft through the air
Propeller Forces
Propeller Efficiency
The ratio of thrust horsepower (how much power is turning the prop) to brake horsepower (how much power is converted to thrust)
Propeller efficiency varies from 50 to 87 percent, depending on how much the propeller “slips”
Pitch is the distance which the propeller would screw through the air in one revolution if there were no slippage
Propeller Slip
The difference between the geometric pitch of the propeller and its effective pitch
Controllable-Pitch Props
Also called “variable-pitch” propMany propellers can change pitch by varying
the angle between the blades and the prop hub
You won’t be flying any of these for a whileFor training, you’ll have a fixed-pitch prop
Propeller Effects on Takeoff
Most single engine aircraft rotate the prop clockwise with respect to the pilot sitting behind it
The direction of rotation causes forces that must be corrected for
These forces include: Torque effect Gyroscopic effect Slipstream effect (corkscrew effect) P-Factor
Torque Effect
Prop turns clockwise; by Newton’s Third Law (equal and opposite reaction), aircraft wants to roll counterclockwise
On the ground, this puts more weight on the left tire
Like leaning into the turn on a snowboard, this tries to turn you left
Gyroscopic Effect
Applying force to a gyroscope’s axis results in a force aligned 90 degrees to that axis
Propeller is a pretty good gyroscopeIn the case of an airplane rotating the prop in
the direction we are, this means that pitching down results in a left yaw
Normally this is a factor primarily in a tailwheel airplane (Piper Cub)
Corkscrew Effect
The high-speed rotation of an aircraft propeller gives a corkscrew or spiraling rotation to the slipstream
At high propeller speeds and low forward speed this spiraling rotation is very compact and exerts a strong sideward force on the aircraft’s vertical tail surface
This results in a left yaw
P-Factor
When an aircraft is flying with a high AOA, the “bite” of the downward moving blade is greater than the “bite” of the upward moving blade
This moves the center of thrust to the right of the prop disc area, causing a yawing moment toward the left around the vertical axis
Descending blade
Aircraft motion
Relative Wind
Aircraft motion
Angle of attack
Descending blade
Angle of attack
“P” Factor
44
Left Turning
Propeller Effects on Takeoff
All the above effects (Torque, Gyroscopic, Corkscrew, P-Factor) result in a tendency to yaw left during takeoff
The solution to correct for all these is right rudder
How much? Enough to keep the airplane on runway centerline
while rolling Enough to keep the ball centered when airborne
Static Stability
Static stability and maneuverability are inversely related
Dynamic Stability
Airplane Equilibrium
Your training aircraft has both positive static stability and positive dynamic stability in all three axes
Longitudinal Stability
Depends on size and location of the wing and tail surfaces in relation to center of gravity
More stable to have CG forward of CL
Longitudinal Stability and Speed
Lateral Stability - Dihedral
Vertical Stability
Aircraft Flight Controls
Elevators control movement about the lateral axis (pitch)
Ailerons control movement about the longitudinal axis (roll)
Rudder controls movement about the vertical axis (yaw)
Elevators
Ailerons
Rudder
Control Effectiveness
Control effectiveness depends on velocity of laminar (streamlined) air moving over the control surface
Faster flow = more effectiveFlow over elevator can be affected by flap
setting in high wing aircraftIf wing is aerodynamically stalled, ailerons
will be less or perhaps not effectiveYou probably can’t fly slow enough to make
the rudder ineffective