2. AE 2350 Lecture #2 April 5, 1999

3. TOPICS ALREADY COVERED We reviewed the history of aeronautics and rocketry. (Read, if you have not done so already, Chapter I, pages 1-46) We discussed the parts of the airplane. (Read Chapter II of text, pages 47-50. Study figure 2.4 which shows possible layouts) We discussed various ways an aircraft is graphically represented.

4. TOPICS TO BE COVERED Roadmap of Disciplines “English” to “S.I.” units Common Aerospace Terminology Airplane Axes and Motion Preliminary Thoughts on Aerospace Design Specifications (“Specs”) and Standards System Integration

5. VARIOUS DISCIPLINES Aerodynamics & Performance Stability & Control Propulsion Structures Design

6. AEROSPACE ENGINEERING DISCIPLINES Aerodynamics (First 3 weeks) Structures (1 week) Flight Mechanics, Stability & Control (2 weeks) Propulsion ( 1 Week) Performance (1 Week) Design - An integration of these disciplines to come up with a new product or concept (Entire course) Astronautics (2 weeks)

7. ENGLISH UNITS U. S. aerospace industries use this convention. –mass : lb m or in slugs –Distance : feet –Time: seconds –Force: lbf (pronounced pound force) –Pressure: psi (pounds per square inch), or in atm –energy: Btu (British thermal units) –Power: HP –Temperature: Fahrenheit or degree Rankine ( R)

8. S. I. UNITS Système International d’Unites Most other European and Asian nations use this. –mass - kg –Distance - m (pronounced meters) –Time - seconds –Force - N (pronounced Newtons) –Pressure - N/m 2, or in atm –energy in Joules –Power in Watts (Joule/sec) –Temperature in Celsius or degree Kelvin ( K)

9. English Units (Continued) Note: –1 slug = 32.2 lb m –1 atm = 14.7 psi (14.7 pounds per square inch) –0 Degrees F = 460 Degrees Rankine –We convert Fahrenheit to Rankine by adding 460 to F –1 BTU = 778.15760 ft lb –1 HP = 550 ft.lb/s

10. 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 = 114.7 psi = 2116 lb/ft 2 = 1.01 x 10 5 N/m 2 1degree K = 1.8 degree R Convert Celsius to Kelvin by adding 273 to Celsius 1HP = 745.69987 Watts g = Acceleration due to gravity = 32.2 ft/s 2 = 9.8 m/s 2

11. Examples Wright Flyer weighed 340 kg –Its weight in English Units: Its wing area was 46.5 m 2 –The area in English units: –Its speed = 56 km/h = 35mph (VFY: verify for yourself, please!)

12. AEROSPACE TERMINOLOGY GW=Gross Weight= The nominal weight for a standard mission before the aircraft (or spacecraft) takes off. Crew Weight: Weight of crew and associated equipment (parachute, oxygen, etc.) P/L= Payload Weight = Weight the aircraft was designed to carry. (passengers weight, baggage for aircraft;satellites, imaging equipment etc. for spacecraft) Fuel/Weight: That required to do the mission plus required reserves Empty Weight = What the aircraft or spacecraft weighs when it is nominally empty (may include trapped fuel ) GW = Crew weight+ P/L + Fuel Weight + Empty Weight

13. AEROSPACE TERMINOLOGY –Wing Loading = Aircraft Weight/Wing Area –Power Loading = Aircraft Weight/ Nominal Engine Power –Aspect ratio, AR = (Wing Span) 2 / Wing Area –Taper ratio = Root Chord/ Tip Chord –Specific Fuel Consumption, sfc = (Fuel Weight)/ (Power x Hour) –Empty Weight Fraction = Empty Weight/ Gross Weight –Payload Fraction = Payload Weight/ Gross Weight

14. TYPICAL WING LOADING Light Civil Aircraft: 10 to 30 lb/ft 2 High Altitude Fighter 30 to 60 lb/ft 2 Interceptor Fighter 120 to 350 lb/ft 2 Long Range Transport 110 to 140 lb/ft 2

15. Axes of an Airplane

16. Roll of an Airplane The longitudinal axis extends lengthwise through the fuselage from the nose to the tail. Movement of the airplane around the longitudinal axis is known as roll and is controlled by movement of the ailerons.

17. PITCH The lateral axis extends crosswise from wingtip to wing tip. Movement of the airplane around the lateral axis is known as pitch. Pitch is controlled by movement of the elevators.

18. Yaw The vertical or normal axis passes vertically through the center of gravity. Movement of the airplane around the vertical axis is yaw. Yaw is controlled by movement of the rudder.

19. AERODYNAMIC CONTROL SURFACES Elevators control pitch angle Ailerons control roll angle Rudder controls yaw angle Flaps increase lift and drag Leading edge slats increase lift Drag brakes increase drag Spoilers reduce lift. Canard is a horizontal control surface placed near the nose.

20. PRELIMINARY THOUGHTS ON DESIGN Design is, in general, –a team effort –a large system integration activity –done in three stages –iterative –creative, knowledge based. The three stages are: –Conceptual design –Preliminary design –Detailed design

21. Conceptual Design What will it do? How will it do it? What is the general arrangement of parts? The end result of conceptual design is an artist’s or engineer’s conception of the vehicle/product. Example: Clay model of an automobile.

22. Preliminary Design How big will it be? How much will it weigh? What engines will it use? How much fuel or propellent will it use? How much will it cost? This is what you will do in this course.

23. Detailed Design How many parts will it have? What shape will they be? What materials? How will it be made? How will the parts be joined? How will technology advancements (e.g. lightweight material, advanced airfoils, improved engines, etc.) impact the design?

24. SPECIFICATION AND STANDARDS The designer needs to satisfy –Customer who will buy and operate the vehicle (e.g. Delta, TWA) –Government Regulators (U.S., Military, European, Japanese…)

25. CUSTOMER SPECIFICATIONS Performance: – Payload weight and volume – how far and how fast it is to be carried –how long and at what altitude –passenger comfort –flight instruments, ground and flight handling qualities Cost Prince of system and spares, useful life, maintenance hours per flight hour Firm order of units, options, Delivery schedule, payment schedule

26. TYPICAL GOVERNMENT STANDARDS Civil –FAA Civil Aviation Regulations define such things as required strength, acoustics, effluents, reliability, take- off and landing performance, emergency egress time. Military –May play a dual role as customer and regulator –MIL SPECS (Military specifications) –May set minimum standards for Mission turn-around time, strength, stability, speed-altitude-maneuver capability, detectability, vulnerability

27. SYSTEM INTEGRATION Aircraft/Spacecraft Design often involves integrating parts, large and small, made by other vendors, into an airframe or spaceframe (also called “the bus.”) Parts include –engines, landing gear, shock absorbers, wheels, brakes, tires –avionics (radios, antennae, flight control computers) –cockpit instruments, actuators that move control surfaces, retract landing gears, etc...

28. Examples of integration Providing smooth airflow into engine inlets free of debris. Insuring that the hot engine does not damage the airframe structure. Providing antenna locations with minimum electromagnetic interference. providing mountings for power actuators that deflect control surfaces, retract landing gear, etc.

29. AEROSPACE DESIGN INVOLVES Lot of Analyses Ground testing and simulation (e.g. wind tunnel tests of model aircraft, flight simulation, drop tests, full scale mock-up, fatigue tests) Flight tests