Aeronautical Engineering Flashcards
nature and scope of the aeronautical engineering profession
study of how things fly, move move through air or move through air into space also:
- what are the human, physical and psychological stresses that affect the performance of pilots?
- what systems and procedures are necessary to design the tools, instruments, wind tunnels or probes that are used to maintain and repair modern aircraft or spacecraft?
- how can aircraft designs be improved in response to environmental concerns regarding noise and emission pollutions?
current projects and innovations
- manufacturing processes that overcome limitations of low metal removal rates and rapid tool wear when working with extremely hard materials
- 3D metal forming process for integrated aero structures, to produce large and intricate, double-curved shapes.
- fuel trials using sustainable alternatives such as biofuels
- fire resistant composite urethane-based components and alumni-trihydrate adhesives
- flight management software and systems that monitor and adjust real-time energy demands to improve efficiency, reduce heat and lower emissions.
health and safety issues
- excessive noise from aircraft in both the field and workshop environments
- exposure to potentially dangerous chemicals and vapours from solvents, surface treatments, fuels etc
- dirt, dust and fibres. they use a wide range of composites that may require sanding or grinding
training for the profession
what do they study?
similar educational foundation of maths and science but also study aerodynamics, aircraft structures, aircraft design and control.
use of flight simulators so student can become familiar principles of flight, the controls and instrumentation
career prospects
military, commercial, general aviation
perform tasks such as:
- investigating aircraft crashes
- overseeing modifications to aircraft
- studying aircraft defects and recommending repairs or modifications
- designing new aircraft or modifications to existing aircraft
- designing equipment or tools to repair or maintain aircraft
- creating instructions on how to use, maintain and calibrate this equipment
- interpreting data and making appropriate recommendations for action
- giving technical and regulatory/legal advice to professionals within the aerospace industry
- discussing designs and data with colleagues, aircraft engineering trades people, aircraft manufacturers and airline owners
- creating paperwork, which is to be kept on file for future reference, for approved data
unique technologies in the profession
advanced composites: metal, polymer and ceramic matrix composites
legal and ethical implications
engineers need to report their findings truthfully and accurately to ensure decisions are properly documented and defensible.
Certification of new aircraft designs, the modification of existing systems and structures and the establishment of repair and maintenance routines.
inflight tests to ensure handling and performance. Maintenance engineers ensure the aircraft is safe and operational. regular inspection, maintenance and servicing. must be licensed.
long term environmental impacts - toxic by-products of manufacturing processes, exposure to dangerous substances, any health and safety issues regarding disposal of aircraft.
engineers as managers
profits, time, prestige
make right decision in the interest of public safety.
relations with the community
traffic problems, flight paths, noise and air pollution, ozone depletion, life cycle impact of aircraft operations and materials.
historical developments in aeronautical engineering
400 BCE: kites used in china
100 BCE: heron developed the aeolipile which helped Newton formulate the 3rd law of motion, explains lift
1783: hot air balloon
1799-1850s: modified gliders.
1903: wright brothers made first sustained flight, 12 seconds and 31 metres
wood and cloth —> steel and aluminium alloys, titanium alloys and carbon fibre.
the effects of aeronautical innovation on people’s lives and living standards
made flying possible. ever increasing power, reliability and fuel consumption. brings people, cultures and commodities close together
environmental implications of flight
- noise pollution
- climate change
- stratospheric ozone reduction, leading to increased surface UV radiation
- local air pollution
aircraft emit carbon dioxide, oxides of nitrogen and sulphur, water vapour, hyrdocarbons and soot particles when flying
solutions to problems
- alternative fuels
- operational improvements through direct routing of smaller aircraft
- higher load factors and optimisation of aircraft speed
- policies and regulations, including more stringent engine emissions certification standards
- intermodal transport networks (Swap short flights with buses and trains)
- technological improvements such as improved engine and airframe designs resulting in great fuel efficeincy
fundamental flight mechanics - lift to drag ratio
during level unpowered flight, the plane will descend rapidly due to the fact that the thrust/drag relationship is unbalanced.
fundamental flight mechanics - effect of angle of attack
angle at which the leading edge of the wing meets the oncoming air. As the angle increases, the lifting force of the wing increases (until stall). the effect is to increase the amount of air redirected downward from both above and below the wing. as the lift increases steadily until the critical angle, it is normally the point where the combined drag is at its lowest that the wing or aircraft is performing at its best.
Bernoulli’s principle and its application to - venturi effect
typically demonstrated through the use of a necked-in tube, where the fluid is forced to speed up as it moves through the necked-in area.
The pressure is less at the necked area than the normal area. also a reduction in temperature.
this has important implications for icing of both external and internal components such as leading edges of wings and the formation of ice in carburettors
Bernoulli’s principle and its application to - lift
the velocity of air over the top of the wing is greater than that below the wing, resulting in pressure variation in the air around the wing, this creates lift.
bending stress - airframes
Stresses induced into the aircraft and their structures include:
- vibration
- wind shear
- take off and landing stresses
- temperature stresses (expansion and contraction)
- pressure differentials, internal pressures are higher than external pressures
types of stress
- tension: pulling or stretching e.g. elevator control cables
- compression: squeezing e.g. when on runway aircraft landing struts are in compression
- shear: sliding one part over another, when 2 pieces of fastened material try and separate. e.g. rivets and bolts
- bending: combination of tension and compression e.g. wing spars
propulsion systems including - internal combustion engines
Take place within an enclosed cylinder, inside cylinder is a moving piston which compresses a mixture
of fuel and air before combustion and is the forced back down the cylinder
propulsion systems including - jet including turbofan, ram and scram
Blades bring air into engine where its compressed. This is completed by a series of rotors and stator blades. Rotors push air backwards into engine, stators straighten the flow and force deeper into a combustion chamber.
Travels from low compression set of rotors and stators to high compression set. Combustion chamber received high pressure air, mixes fuel with it and burns mixture. Hot, very high velocity gases are produced striking the blades of the turbine spinning rapidly. Hot gas expelled through the exhaust section both straightening the flow of gas and inducing
propulsion systems including - turboprop
Propeller driven by a gas turbine engine. Thrust produced 90% by propeller and 10% by exhaust gas
- Propellers force air into a series of compressors where they are forced into a combustion chamber, here
they are combined with fuel and ignited to primarily turn the driveshaft in turn rotating the prop and thus
creating thrust.
- Propellers reduce efficiency at high speeds and as such aren’t used on aircrafts travelling over 850km/h.
Only used on smaller, private aircrafts
propulsion systems including - rockets
jhv
fluid mechanics - Pascal’s principle
basis of all hydraulic systems.
in aviation, two prospects of fluid mechanics considered are: the systems of sensors used in the aircrafts instruments, the systems of fluid (liquid and air) pressure used in an aircrafts avionics
hydraulic systems take engine power and convert it to hydraulic power. the power can be distributed throughout the aircraft by tubing.
pressures measured in megapascals.
actuating cylinder converts hydraulic or fluid power into movement or mechanical energy
fluid mechanics - hydrostatic and dynamic pressure
hyrdostatic - static pressure in the atmosphere at any point is exerted equally in all directions. Static pressure does not involve relative movement of the air. It is produced by the weight of all the molecules in the air. Static pressure is measured on the surface of an aircraft by a static vent.
dynamic - is an additional pressure that is generated due to relative movement and is felt by a body that is moving relative to the air. Just how strong this is depends on the: density of the air, and the speed of the body relative to the air.
fluid mechanics - applications to aircraft components and instruments
altimeters, airspeed indicators, vertical speed indicators.
each of these basic instruments are measures of air pressure outside the aircraft. need to take in to account dynamic and hydrostatic pressure.
