Aircraft Flight Principles (I) - Unit 1 PDF

AIRCRAFT FLIGHT PRINCIPLES (I) (AED 305) Prepared By Dr. S. O. Balogun 01/02/2024 AEROSPACE ENGINEERING. AIR FORCE INSTITUTE OF TECHNOLOGY PPT 1. 1  Course Outlin...

AIRCRAFT FLIGHT PRINCIPLES (I) (AED 305) Prepared By Dr. S. O. Balogun 01/02/2024 AEROSPACE ENGINEERING. AIR FORCE INSTITUTE OF TECHNOLOGY PPT 1. 1  Course Outline Review of the underlying relevant physics concepts and Laws: Newton’s laws, SI and Imperial Engineering Systems of Units, Hydrostatic Pressure, Manometry, Work, Energy, Vector Addition and Resolution. Nature of Aerodynamic forces on an aircraft, Concept of an Aerofoil (Lift, Drag Ratio, Glide Angle, Coefficients of Lift and Drag) Properties of the International Standard Atmosphere. 01/02/2024 AEROSPACE ENGINEERING. AIR FORCE INSTITUTE OF TECHNOLOGY, KADUNA PPT 1. 2  Reference Text Books Fundamentals of Aerodynamics, by Anderson, Jr., J.D., International edition, McGraw Hill, 2001, ISBN: 0‐07‐118146‐6. Aerodynamics by L J. Clancy. Pitman Aeronautical Engineering Series. 01/02/2024 AEROSPACE ENGINEERING. AIR FORCE INSTITUTE OF TECHNOLOGY, KADUNA PPT 1. 3  Introduction Flight principles refers to the fundamental concepts and principles that govern the science and engineering behind the flight of aircraft. These principles are the basis for the design, operation, and safety of aircraft. 01/02/2024 AEROSPACE ENGINEERING. AIR FORCE INSTITUTE OF TECHNOLOGY, KADUNA PPT 1. 4  Review of underlying concepts Newton’s Laws of Motion First , Second and Third laws. The second law is the most commonly used, and states mathematically that 01/02/2024 AEROSPACE ENGINEERING. AIR FORCE INSTITUTE OF TECHNOLOGY, KADUNA PPT 1. 5  Review of underlying concepts Cont’d Use of Units Quantity SI Units Imperial Units Length meters (m) foot (ft) Mass kilogram (Kg) Pound (lb) Time seconds (s) Second (s) Temperature kelvin (K) Force (F=ma) Newton (1 kg x meter/second2 ) 01/02/2024 AEROSPACE ENGINEERING. AIR FORCE INSTITUTE OF TECHNOLOGY, KADUNA PPT 1. 6  Use of Units Cont’d CONVERSION FACTORS 1 ft = 0.3048 m 1 slug = 14.594 kg 1 slug = 32.2 lb m 1 lb m = 0.4536 kg 1 lb = 4.448 N 1 atm = 2116 lb/ft 2 = 1.01 × 10 5 N/m 2 1 K = 1.8°R 01/02/2024 AEROSPACE ENGINEERING. AIR FORCE INSTITUTE OF TECHNOLOGY, KADUNA PPT 1. 7  Review of underlying concepts Cont’d 01/02/2024 AEROSPACE ENGINEERING. AIR FORCE INSTITUTE OF TECHNOLOGY, KADUNA PPT 1. 8  Review of underlying concepts Cont’d 01/02/2024 AEROSPACE ENGINEERING. AIR FORCE INSTITUTE OF TECHNOLOGY, KADUNA PPT 1. 9  Review of underlying concepts Cont’d Vector Addition and Resolution 01/02/2024 AEROSPACE ENGINEERING. AIR FORCE INSTITUTE OF TECHNOLOGY, KADUNA PPT 1. 10  Fundamental Physical Quantities of Flowing Gas 01/02/2024 AEROSPACE ENGINEERING. AIR FORCE INSTITUTE OF TECHNOLOGY, KADUNA PPT 1. 11  Fund’l Physical Quantities of Flowing Gas Cont’d Flow velocity: The velocity at any fixed point B in a flowing gas is the velocity of an infinitesimally small fluid element as it sweeps through B. Streamline of a flow is the path taken by a moving fluid element. 01/02/2024 AEROSPACE ENGINEERING. AIR FORCE INSTITUTE OF TECHNOLOGY, KADUNA PPT 1. 12  The Standard Atmosphere Atmosphere Basic Categories of Aerospace Vehicle Atmospheric vehicles - such as airplanes and helicopters, which always fly within the sensible atmosphere; and Space vehicles - such as satellites, the Apollo lunar vehicle, and deep-space probes, which operate outside the sensible atmosphere. Space vehicles fly through the earth’s atmosphere during their blastoffs from the earth’s surface and again during their re-entries and recoveries after completion of their missions. 01/02/2024 AEROSPACE ENGINEERING. AIR FORCE INSTITUTE OF TECHNOLOGY, KADUNA PPT 1. 13  The Standard Atmosphere Cont’d The earth’s atmosphere consistently changes with time and with location. The pressure and temperature of the atmosphere depend on altitude, location on the globe, time of the day season, and even solar sunspot. Due to all these variation, a standard atmosphere is defined in order to have a common reference for flight test and performance evaluations of aircraft. 01/02/2024 AEROSPACE ENGINEERING. AIR FORCE INSTITUTE OF TECHNOLOGY, KADUNA PPT 1. 14  The Standard Atmosphere Cont’d ADOPTING THE STANDARD ATMOSPHERES Compilation by different agencies using slightly different experimental data in the models Difference insignificant below 30 Km (100, 000 ft.) for all practical purpose – domain of contemporary airplanes First standard atmosphere simultaneously developed in USA and Europe in 1920’s Models were reconciled and an internationally accepted model was adopted in 1952 by ICAO and subsequently NACA. 01/02/2024 AEROSPACE ENGINEERING. AIR FORCE INSTITUTE OF TECHNOLOGY, KADUNA PPT 1. 15  The Standard Atmosphere Cont’d 01/02/2024 AEROSPACE ENGINEERING. AIR FORCE INSTITUTE OF TECHNOLOGY, KADUNA PPT 1. 16  Altitudes Cont’d Pressure altitude: Is the is the altitude in the international standard atmosphere which corresponds to the actual pressure encountered by an aerospace vehicle in flight. Density altitude: Is the is the altitude in the international standard atmosphere which corresponds to the actual density encountered by an aerospace vehicle in flight. Temperature altitude: Is the is the altitude in the international standard atmosphere which corresponds to the temperature encountered by an aerospace vehicle in flight (Explanations will follow in the later section) 01/02/2024 AEROSPACE ENGINEERING. AIR FORCE INSTITUTE OF TECHNOLOGY, KADUNA PPT 1. 17  Atmospheric Layers Exosphere Varies with altitude. Shell called shell is the heterosphere. Above 90 km, the (up to 800km) composition Thermosphere (up to 600km) Mesosphere (up to 85km) Stratosphere Below 90 km, the called shell is the Is constant. Shell (up to 50km) homosphere. composition Troposphere (0 -15 Km) 01/02/2024 AEROSPACE ENGINEERING. AIR FORCE INSTITUTE OF TECHNOLOGY, KADUNA PPT 1. 18  Characteristics of the Atmosphere The air that surrounds the earth is made of 78% Nitrogen, 21% Oxygen and 1% other gases. Percentage is consistent up to approximately 50 miles above MSL. The density of air is an important property of the atmosphere. 01/02/2024 AEROSPACE ENGINEERING. AIR FORCE INSTITUTE OF TECHNOLOGY, KADUNA PPT 1. 19 Characteristics of the Atmosphere Cont’d The pressure, temperature and humidity of the air affects density. – P1/T1d1 = P2/T2d2 From Universal Gas Law The Effect of Atmospheric Pressure on Density: – As we climb in the atmosphere the atmospheric pressure reduces. – The density of air is directly proportional to the atmospheric pressure. 01/02/2024 AEROSPACE ENGINEERING. AIR FORCE INSTITUTE OF TECHNOLOGY, KADUNA PPT 1. 20  Characteristics of the Atmosphere Cont’d The effect of Atmospheric Temperature on its Density: – Density of air is inversely proportional to its temperature. Humidity in the Atmosphere and its effect on Density: – Water vapour suspension in the air is found up to a height of approximately 6 miles (9.6 km) in varying quantity. – The actual amount depend on temperature. Hot day holds more water vapour and a cold day. – Relative humidity is inversely proportional to density. 01/02/2024 AEROSPACE ENGINEERING. AIR FORCE INSTITUTE OF TECHNOLOGY, KADUNA PPT 1. 21  Characteristics of the Atmosphere Cont’d Overall Altitude effect on density: – As already stated, the main factors affecting density are pressure, temperature and humidity. – Pressure decreases as air thins ouy, temperature decreases to a certain point, and humidity decreases in line with temperature. – Density changes directly with pressure and humidity and inversely with temperature. But overall, density will decrease in line with pressure and decrease as altitude increases. 01/02/2024 AEROSPACE ENGINEERING. AIR FORCE INSTITUTE OF TECHNOLOGY, KADUNA PPT 1. 22 Characteristics of the Atmosphere Cont’d 01/02/2024 AEROSPACE ENGINEERING. AIR FORCE INSTITUTE OF TECHNOLOGY, KADUNA PPT 1. 23  International Standard Atmosphere (ISA) The International Standard Atmosphere (ISA) is an atmospheric model of how the temperature, pressure, density, and viscosity of the Earth’s atmosphere change over a wide range of altitudes. It has been established to provide a common reference for the atmosphere consider standard (with an average solar activity and in latitudes around 45N). The keynote of the international standard atmosphere is the defined variation of temperature T with altitude, based on experimental evidence. Temperature distribution of ISA 01/02/2024 AEROSPACE ENGINEERING. AIR FORCE INSTITUTE OF TECHNOLOGY, KADUNA PPT 1. 24  ISA Cont’D Equations for the Calculation of ISA Properties 01/02/2024 AEROSPACE ENGINEERING. AIR FORCE INSTITUTE OF TECHNOLOGY, KADUNA PPT 1. 25  ISA Cont’d ISA EQUATIONS Considering Equation (1.1), Equations (1.2)-(1.3), the variations of ρ and p within altitude can be obtained for the different layers of the atmosphere that affect atmospheric flight: 01/02/2024 AEROSPACE ENGINEERING. AIR FORCE INSTITUTE OF TECHNOLOGY, KADUNA PPT 1. 26  ISA Cont’d Gradient Regions: T (at altitude) = T(at sea level) + α Δh Where α is a constant for specific layer. At the troposphere α is -6.5 oC per 1000 meters 01/02/2024 AEROSPACE ENGINEERING. AIR FORCE INSTITUTE OF TECHNOLOGY, KADUNA PPT 1. 27  ISA Cont’d Since Lapse rate is Substituting in eqn. 1.3 will give Integrating Thus 01/02/2024 AEROSPACE ENGINEERING. AIR FORCE INSTITUTE OF TECHNOLOGY, KADUNA PPT 1. 28  ISA Cont’d From equation of state Hence, 01/02/2024 AEROSPACE ENGINEERING. AIR FORCE INSTITUTE OF TECHNOLOGY, KADUNA PPT 1. 29  ISA EQUATIONS Contd Isothermal Regions: The pressure at a point can be obtained by integrating 01/02/2024 AEROSPACE ENGINEERING. AIR FORCE INSTITUTE OF TECHNOLOGY, KADUNA PPT 1. 30  ISA Cont’d Also from equation of state Thus Relationship between h and hG: where r is earth radius. 01/02/2024 AEROSPACE ENGINEERING. AIR FORCE INSTITUTE OF TECHNOLOGY, KADUNA PPT 1. 31  ISA Cont’D Sea level conditions: T = 288.16 K or 518.69 oR P = 1.01325 ×105 N/m2 or 2115.2 lb/ft2 ρ = 1.225 kg/m3 or 0.002377 slug//ft3 Gas constant, R is 287.053 J/kg K Acceleration due to gravity, g = 9:80665 m/s2 01/02/2024 AEROSPACE ENGINEERING. AIR FORCE INSTITUTE OF TECHNOLOGY, KADUNA PPT 1. 32  ISA TABLE 01/02/2024 AEROSPACE ENGINEERING. AIR FORCE INSTITUTE OF TECHNOLOGY, KADUNA PPT 1. 33  ISA TABLE 01/02/2024 AEROSPACE ENGINEERING. AIR FORCE INSTITUTE OF TECHNOLOGY, KADUNA PPT 1. 34  ISA Cont’d Pressure altitude: Is the is the altitude in the international standard atmosphere which corresponds to the actual pressure encountered by an aerospace vehicle in flight. Density altitude: Is the is the altitude in the international standard atmosphere which corresponds to the actual density encountered by an aerospace vehicle in flight. Temperature altitude: Is the is the altitude in the international standard atmosphere which corresponds to the temperature encountered by an aerospace vehicle in flight 01/02/2024 AEROSPACE ENGINEERING. AIR FORCE INSTITUTE OF TECHNOLOGY, KADUNA PPT 1. 35  ISA Cont’d The ambiguity of the use of temperature altitude: If the ambient temperature in the air ahead of an airplane in flight is said to be 240 K. At what temperature altitude is the airplane flying? From the ISA table, this temperature corresponds to altitudes; 7.4 km, 33 km and about 63km. Hence, we conclude that the definition of temperature altitude has limited usefulness. 01/02/2024 AEROSPACE ENGINEERING. AIR FORCE INSTITUTE OF TECHNOLOGY, KADUNA PPT 1. 36  ISA Cont’d CALCULATIONS OF ISA PROPERTIES Example 1: Calculate the standard atmosphere values of T , p , and ρ at a geopotential altitude of 5 km. Solution: To be done in class. 01/02/2024 AEROSPACE ENGINEERING. AIR FORCE INSTITUTE OF TECHNOLOGY, KADUNA PPT 1. 37  ISA Cont’d Example 2: If an helicopter is flying at an altitude where the actual pressure and temperature are 1.7941×103 lb/ft2 and 504.43 °R, respectively, what are the pressure, temperature, and density altitudes? Solution: From the ISA Table lookup corresponding altitudes to the pressure and temperature values. These are – Pressure altitude = 4500 ft Temperature altitude = 4000 ft Density = P / RT = 1.7941×103 / 1716 x 504.43 = 2.0727x10-3 slug//ft3 01/02/2024 AEROSPACE ENGINEERING. AIR FORCE INSTITUTE OF TECHNOLOGY, KADUNA PPT 1. 38  ISA Cont’d Exercise: 1. Calculate the standard atmosphere values of T , p , and ρ at a geopotential altitude of 17 km. Note that the condition of T , p , and ρ at the tropopause start altitude (11 km) is 216 K, 2.26 x 10 4 n/m 2 and 0.367 kg / m3. 2. Consider an airplane flying at some real altitude. The outside pressure and temperature are 2.65 × 10 4 N/m 2 and 220 K, respectively. What are the pressure and density altitudes? 3. During a test flight, the pilot maintained his flight level at a standard altitude of 10 ft. Calculate the atmospheric conditions of T , p , and ρ at this altitude. 01/02/2024 AEROSPACE ENGINEERING. AIR FORCE INSTITUTE OF TECHNOLOGY, KADUNA PPT 1. 39  Summary Underlying concepts Altitude Layers of the atmosphere Atmospheric properties Standard atmosphere Atmospheric condition equations Calculation of atmospheric properties 01/02/2024 AEROSPACE ENGINEERING. AIR FORCE INSTITUTE OF TECHNOLOGY, KADUNA PPT 1. 40