205 AE Aircraft Operations Class Notes
1 Fundamentals of Flight
1.1 Aircraft components and terminology
1.1.1 Terminology
Distance: 1 nm = 1 minute of latitude =1.15 sm = 6,076 ft Speed: 1 knot = 1 nm/hr = 1.15 mph Altitude: ft msl vs. ft agl Weight: g = 9.81 m/s2 = 32.2 ft/s2 Category and class Airplane Single engine land Single engine sea Multi engine land Multi engine sea Glider Lighter-than-air Airship Balloon Rotorcraft Helicopter Gyroplane Ultralights
1.1.2 Aircraft components
Airframe Fuselage Wing High wing Good downward view External bracing Gravity fed fuel supply Difficult to fuel More susceptible to winds close to ground Less susceptible to ground effect Low wing Good sideways view Internal bracing Requires fuel pump Easy to fuel Less susceptible to winds close to ground More susceptible to ground effect
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Empennage (tail assembly) Horizontal stabilizer Vertical stabilizer Pusher vs. tractor Canard vs. tail Tricycle vs. conventional (benefits/disadvantages) Fixed vs. retractable (benefits/disadvantages)
1.1.3 Wing geometry
Area (S) Wingspan (b) Chord (c) Root (c0) Tip (ct) Mean (cmean) cmean = S/b For trapezoidal wing, cmean = (c0+ct)/2 Aspect ratio (AR) AR = b2/S AR = b/cmean Taper () = ct / c0 Wing sweep () Twist Angle of attack at wing tip is less than at wing root Inboard portion of wing stalls before outboard portion Allows aileron control in stall Aerodynamic twist: Use of two airfoil shapes to achieve same effect Dihedral Angle of incidence
1.2
Review of fundamentals
1.2.1 Vectors
Vector: magnitude and direction (x, y) or (, ) Addition: graphical, parallelogram Resolution Breaking down a vector into two perpendicular components Examples of vector quantities: Velocity: Speed and direction Acceleration: Change of velocity with respect to time Force: Action and direction (different than velocity) Aircraft travels in direction of velocity vector Relative wind is opposite of velocity vector/flight path
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1.2.2 Newton's Laws
Isaac Newton (1642-1727), Principia, July 5, 1687 First: Uniform motion in absence of net force "Every body perseveres in its state of rest, or of uniform motion in a right line, unless compelled to change that state by forces impressed thereon." A body travels in uniform motion (constant velocity) in the absence of a net force. Second: F = ma "The alteration of motion (i.e., momentum) is ever proportional to the motive force impressed; and is made in the direction of the line in which that force is impressed." Acceleration is proportional to the net force and in the same direction. Third: FAB = FBA "To every action there is always opposed an equal reaction: or the mutual actions of two bodies upon each other are always equal, and directed to contrary parts." For every action there is an equal and opposite reaction. Acceleration due to gravity: g=9.81 m/s2=32.2 ft/s2
1.3
Aerodynamics
1.3.1 Pressure
Static p Standard atmosphere ("sea-level pressure") T = 15C = 59F p = 1 atm = 101.325 kPa = 29.92 in. Hg = 14.7 psi Dynamic q = v2 Stagnation (or total or ram or head pressure) p+q Bernoulli's principle p + q is constant (along a streamline in an incompressible, non-viscous fluid) Law of continuity Av is constant
1.3.2 Lift
Resolve total aerodynamic force into lift and drag Lift (perpendicular to v and wingspan) Laminar vs. turbulent flow Lift (or, more precisely, the lift coefficient CL) increases with until stall (critical angle of attack) Maximum CL occurs at stall Stall is only dependent on the critical angle of attack Stall and airspeed are related Increasing the angle of attack usually reduces airspeed The airspeed at which the critical angle of attack is reached is the stall speed Stall speed varies depending on conditions of flight; critical angle of attack does not
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Airfoil shape Leading edge Trailing edge Chord line Upper camber Lower camber Downwash L = v2CLS = qCLS
1.3.3 Drag
Parallel to v Induced drag (Di) Parasite drag (Dp) Form (pressure) Skin friction Interference D = Di + Dp Di is proportional to 1/v2 Dp is proportional to v2 When D is a minimum: L/D is at a maximum Speed for best glide Slowing down or speeding up increase drag at this speed
1.3.4 Factors that affect lift and drag
Aerodynamic design Speed Wing surface area Air density Temperature Altitude Humidity Why do aircraft take off into the wind?
1.4
Forces in flight
L, W, T, D In straight, unaccelerated flight: L+W+T+D=0 In level flight: L = W T = D
1.5
Flaps
Types: Plain, split, slotted, fowler Change airfoil or surface area Increase lift and drag Reduce stall speed Allow for slower/steeper flight
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1.6
Vortices
Span-wise (3-D) effect Downwash Wake turbulence Effect on vortices by crosswind Ground effect (occurs when the altitude equals b) Reduction in induced drag Change in Significance of airspeed control
1.7
Maneuvering
1.7.1 Attitude
Center of gravity L:D = glide path Gliders Turning Accelerated Load factor Movements: pitch, roll, yaw Axes: lateral, longitudinal, vertical Control surfaces: elevator, ailerons, rudder Trim tabs: used to offset control forces Pitch can usually be uncoupled from roll and yaw
1.7.2 Propeller effects (left turning tendency)
Dominant at slow speed, high lift situations Torque reaction: clockwise prop, counterclockwise reaction Precession: gyroscopic effect of raising tail Left turning effect in taildraggers Right turning effect in tricycle gear aircraft Slipstream: strikes tail P-factor: nose-high attitude, more lift by right (descending) blade
1.7.3 Turns
Turn: apply ailerons to roll aircraft to tilt the lift vector Need rudder in same direction as ailerons, so that nose of aircraft tracks turning circle (coordinated flight) Adverse yaw Downward aileron movement increases lift and drag Unbalanced drag Countered with rudder input
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1.8
Stability and control
1.8.1 Stability: tendency to return to equilibrium
Static: Initial tendency Dynamic: Reaction over time Only of interest if system has static stability Beyond scope of this class Stability around all three axis of rotation must normally be included as part of an aircraft's design
1.8.2 Directional (yaw) stability
Keel effect Added surface behind CG Reduced as center of gravity moves aft
1.8.3 Lateral (roll) stability
Dihedral (sideslip effect) Force caused by vertical tail Stability is light Spiraling tendency
1.8.4 Longitudinal (pitch) stability
Airfoil creates downward pitch (Mac) Balanced by upward pitch from wing and tail lift Mac increases with Neutral point: aft limit of CG
1.9
Weight and balance
1.9.1 Moment
Force acting at the end of a lever arm about a fulcrum Force = weight Fulcrum = CG Balance requires equal moments
1.9.2 Center of gravity CG = M/W
Datum: arbitrary reference point Basic empty weight: Empty aircraft Unusable fuel Standard engine oil supply CG too far forward: High control forces, including high stick pressure to rotate High stalling speeds Reduced landing/take-off performance
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CG too far aft Unstable flight Increased risk of structural damage due to light control forces Violent stalls May cause unrecoverable spins
1.10 Flight instruments and controls 1.10.1 Controls
Dual controls Connected to control surfaces Cables Control rods Hydraulic Electronically (fly-by-wire) Yoke/stick/side-stick Elevator Aileron Pedals Rudder Nose wheel Brakes Flaps Switch Lever Throttle (black) Mixture (red) Propeller control (blue; for aircraft with variable pitch propellers) Trim wheels Landing gear
1.10.2 Flight instruments
Altimeter (static): 1,000 ft Kollsman window: altimeter setting (current sea level P) True altitude (used for navigation) Pressure altitude (used for performance calculations) Flight levels Vertical speed (static): 100 ft/min Airspeed (pitot-static): knots or mph Indicated (used for performance calculations) Calibrated True (used for navigation) White arc: vS0 to vFE Green arc: vS1 to vNO (maximum structural cruise) Yellow arc: vNO to vNE Magnetic compass 5 increments and cardinal headings (relative to the magnetic north pole) Subject to acceleration/turn errors Compass error (deviation): corrected using compass correction card
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Gyroscopic properties Rigidity in space Precession Heading indicator ("directional gyro") Must be set with reference to magnetic compass Must be periodically checked against magnetic compass due to precession Attitude indicator ("artificial horizon") Turn coordinator (measures yaw and roll) Shows direction of turn Standard rate of turn: 2 min. or 3/min Inclinometer Ball shows if turn is coordinated Pilot applies rudder to correct ("step on the ball") Slip: bank angle too high for turn rate Skid: turn rate to high for bank angle Gyroscopic instrument power systems Vacuum/air pressure: AI and DG Electrical: turn indicator Instrument scan Basic T centered on AI Instrument failures Static/dynamic port (alternate static pressure source) Vacuum failure Electrical failure Miscellaneous controls and instruments (instrument panel illustrations)
1.11 Aircraft performance 1.11.1 Stall speed
In straight and level flight, L = W As v decreases, must increase to maintain level flight The speed at which reaches stall angle is stall speed, VS In a level turn, L = W/cos To maintain level flight, must be higher than that required for the same v in straight flight Lift increases with bank angle Stall speed increases with bank angle (the higher the stall speed, the lower the margin allowed in slow flight) Flaps increase lift, allowing for a lower to maintain level flight, therefore reducing stall speed
1.11.2 Take-off
Take-off distance theory F = TD(WL) = ma Must accelerate to some margin above VS
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Take-off distance is affected by: Gross weight Pressure altitude Temperature Winds Runway conditions
1.11.3 Climb rate
Power Force for distance per time Force times speed PR = DV PA = TV Excess power: PA PR Rate of climb (R/C) R/C = (PA PR)/W Maximum rate of climb occurs at maximum excess power Climb rate is affected by: Gross weight Pressure altitude Temperature Speed at R/Cmax is Vy Most altitude in a given amount of time Speed at best angle of climb is Vx Most altitude in a given amount of distance
1.11.4 Ceiling
Excess power decreases with altitude Absolute ceiling Theoretical ideal that cannot be reached in practice No excess power R/C = 0 Service ceiling Practical limit R/C = 100 ft/min
1.11.5 Cruise and maneuvering
Cruise performance is affected by: Pressure altitude Temperature Power setting Range/endurance Flight envelope: stall speed and maximum power Load factor n = 1+a/g
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Maneuvering speed VA Maximum speed at which a sudden increase of will not damage aircraft Abrupt movement of controls Gusts The higher the weight, the lower the maneuvering speed At high W, is relatively high to produce higher L Margin of is relatively low VA is higher Turn rate Decreases with V Increases with bank angle () = V-1 g tan Turn radius Increases with V2 Decreases with R = V2 (g tan )-1
1.11.6 Landing
Landing distance is affected by: Pressure altitude Temperature Ground speed Air speed Wind speed and direction Flaps Obstruction height Runway conditions Landing distance can be reduced by: Brakes Air brakes, spoilers, flaps Thrust reversers Drag chutes
1.11.7 Engine failure (or glider)
Minimum rate of sink Best glide speed: minimum ratio of rate of sink to forward speed
1.12 Propulsion systems
Increasing the speed of the incoming airflow produces thrust T = QV Q = V Note that air density directly affects thrust
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1.12.1 Piston-engine propeller
Reciprocating engine Internal combustion Power proportional to: Displacement Pressure Engine speed (rpm) Propeller pitch Low pitch Less drag Higher rpm More power Used for take-off High pitch More drag Lower rpm Less power (better fuel efficiency) Used in cruise Variable pitch propeller (constant speed propeller) Propeller pitch can be controlled by pilot using propeller control Better fuel efficiency Adds complexity, cost, and weight Propeller is like a rotating wing Angle of attack depends on: velocity Forward Rotational velocity Twist is used to maintain constant angle of attack
1.12.2 Jet engines
Turbojet All air flows through combustion chamber High thrust, but inefficient and loud Best for military applications and high performance business jets Turbofan Some air bypasses combustion chamber More efficient and quieter Efficiency depends on bypass ratio Best for large passenger and cargo aircraft Turboprop No duct, uses propeller, and requires gear box High power output for size and weight High efficiency at slow speeds Best for small passenger aircraft
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2 Aircraft Operations
2.1 General aviation aircraft
2.1.1 Definition
Non-military Civil Public Non-commercial or non-scheduled commercial (i.e., "on demand") Typical aircraft Airplanes Up to 10 seats Less than 12,500 lbs All non-airplane categories not used for military purposes
2.1.2 Uses
Personal Recreational Transportation Business Instruction Sport Homebuilt Balloons Gliders Antiques Racing Aerobatics Ultralights Emergency Medical evacuation Civil defense/damage assessment Law enforcement Fire fighting Commercial Air taxi Sightseeing Aerial application Aerial advertising Aerial photography Fish and wildlife Media coverage Utility patrol aircraft Construction
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2.1.3 Airplane characteristics
Single engine or light twin Piston engine Cost, less than appr. $1,000,000 Individual ownership Older technology
2.1.4 Manufacturers
"Big three": Beechcraft (owned by Raytheon) Cessna (owned by Textron) Piper
2.1.5 Statistics
Decline in general aviation 1978: 17,811 aircraft shipped 1995: 1,077 (50% piston-engine, 30% exported) The average age of a single-engine piston aircraft is 27 years. Use: Personal Flying 32.6 % Instructional 19.2 % Business 13.7 % Corporate 10.9 % Aerial Observation 7.2 % Air Taxi 6.0 % Aerial Application 4.8 % Other 5.5%
2.2
Business aircraft
2.2.1 Executive
Executive is pilot and/or owner Single or multi-engine piston
2.2.2 Corporate
Corporation is owner Pilot is employee Multi-engine turboprop or jet Cost: $10,000,000
2.3
Military aircraft
Aviation technology has its focus on military aircraft Technology transfer Glass cockpit Head-up display Military aircraft types and designations
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2.4
Passenger aircraft
2.4.1 Scheduled service
Part 135 Commuter/regional airlines Turboprops Code sharing Part 121 National/major airlines Turbofans
2.4.2 Unscheduled service
Charter Turbojets/fans Older technology
2.5
Cargo aircraft
Air freight vs. express cargo vs. belly cargo Modified passenger aircraft Older technology Custom designed cargo aircraft
2.6
Trade/industry organizations
General aviation: Aircraft Owners and Pilots Association (AOPA) Business aviation: National Business Aviation Association (NBAA) Regional airlines: Regional Airline Association (RAA) National/major airlines: Air Transport Association (ATA)
2.7
Weather
2.7.1 Weather/Automatic Terminal Information Service (ATIS) elements
Wind direction, speed, and gusts Visibility Ceiling VMC vs. IMC Weather/precipitation Temperature and dew point Altimeter setting Remarks Runway conditions Braking action Closures Bird activity
2.7.2 Weather products
Charts Radar Surface weather report (METAR)
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Special weather report (SPECI) Terminal area forecast (TAF) Area forecast (FA) Airmet (WA) Sigmet Winds aloft Pilot reports (PIREPs) Notices to airmen (NOTAMs)
2.7.3 Sources and distribution of weather products
National Weather Service is the root source for most distribution channels Flight Service Stations (1-800-WXBRIEF) En Route Flight Advisory Service (EFAS/Flight Watch) Transcribed Weather Broadcasts (TWEB) Air Traffic Control Direct User Access Terminal (DUAT) Commercial sources
2.8
Air traffic control and radar surveillance
2.8.1 Radar
Reflection of radio waves used to measure range (distances) and azimuth (direction) Primary radar Radar return ("target") depends on size of aircraft No altitude information No information about aircraft Secondary radar Aircraft are equipped with transponders Ground based radar interrogates transponders Stronger than primary radar Transponder returns beacon codes Codes are used to identify aircraft Mode C transponders also transmit aircraft's altitude Most radar transmitters have primary and secondary Radar equipment Airport Surveillance Radar Air Route Surveillance Radar Precision Approach Radar Radar scope
2.8.2 Airspace
Class G Uncontrolled airspace No requirements Class E General controlled airspace Surface Extension to Class B/C/D surface areas Transition
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En route domestic areas Federal airways Offshore airspace areas No requirements Stricter VFR minima than Class G From surface or end of Class G to beginning of next class or 18,000 ft msl Class D Airports with control towers Requirements Two-way radio Must establish contact 5 sm radius from surface to 2,500 ft agl Class C Airports with terminal radar approach control (TRACON) Requirements Two-way radio Must establish contact Mode C transponder Radar services are provided 5 nm inner core from surface to 4,000 ft agl 10 nm outer core from 1,200 to 4,000 ft agl Class B Large metropolitan airports Requirements Private pilot's license Must establish contact Mode C transponder (Mode C veil: 30 nm radius) Surface to 10,000 ft msl Radar services are provided 20 nm layered airspace Class A High altitude Requirements IFR only Radar services are provided Altitudes are pressure altitudes Altimeter setting is 29.92 Altitude is reported as flight levels From 18,000 ft to FL600 Class F There is no Class F airspace in the US
2.8.3 Air traffic control services
Flight rules VFR vs. IFR VMC vs. IMC Minima
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Flight plans Optional for VFR Required for IFR Flight Service Stations (FSS) Weather briefings Flight plans Air Traffic Control Towers (ATCT) Visual sequencing of aircraft Separation of IFR traffic Automatic Terminal Information Service (ATIS) Clearance delivery Ground control Local control Terminal Radar Approach Control (TRACON) Terminal radar services Approach Departure Interface between ATCT and ARTCC Air Route Traffic Control Center (ARTCC) En route radar services
2.9
Airports
2.9.1 Types of airports
Tower vs. non-tower Public vs. private use Heliports Sea plane bases
2.9.2 Airport operations
Layout Runway Taxiway Aircraft parking apron Markings White: Runway Yellow: Taxiway Lights White: Runway Blue: Taxiway Red/green: Threshold Red: Obstructions Signs Wind indicator (with optional segmented circle to highlight wind sock location and show direction of traffic patterns) Left traffic pattern unless otherwise specified
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2.10 Aviation safety/emergencies
Design for safety by incorporating redundancy Certification Training Aviate, navigate, communicate Emergency vs. urgency Common emergencies Weather IMC Thunderstorms Icing Cross winds Turbulence Fuel Mechanical Engine failure Landing gear failure Navigation/radio/instrument failures In-flight fire Pilot error Loss of situational awareness Actions Checklists Radio (121.5) Transponder ELT Forced landing
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3 Navigation
Aircraft's position and orientation with respect to earth Fix Distance and bearing Lines of position Coordinate system Methods of...