Aircraft Structures Definitions Angle of attack A - the angle between the chord line of a wing or other aerodynamic surface and the oncoming Access panel air - removable panel for inspection or maintenance Anhedral (negative Dihedral) - a wing in a reverse v-form Aft - near of in the direction of the rear of the Aspect ratio aircraft - the ratio of wing span to average chord, an indication of the slenderness of a wing Aerodynamics Assembly - the study of how the moving body (aircraft) - building parts and components together to an interacts with air flowing around it, flies aircraft Aerodynamic centre Auxiliary power unit - the point of application for additional - system to generate electric power when the aerodynamic loads engines are not running Aeroelasticity Auxiliary spar - the study how to find measures against flutter - an extra beam in the root in the wing for (undamped vibration in the structure due to extra strength aerodynamic loads Airfoil B - wing-section Beam Afterburner - a structural member loaded at an angle (often - extra injection of fuel in extra combustion at a right angle) to its length chamber between the turbine and the nozzle of the engine; creates a higher thrust Bearing stress - used for bolted or riveted joints – load/bolt Age hardening, ageing diameter times material thickness - strengthening at room temperature of a quenched metal alloy by very small and Bending moment uniformly dispersed particles that precipitate - the product of a force and its moment arm from supersaturated solution Biplane Ageing - aircraft with an upper and lower wing on top - decrease of mechanical properties of polymer of each other matrix composites or adhesives by exposure to a wet environment Bird strike - an impact of a bird on the structure Aileron - control surface for aircraft rolling Blade - one half of a propellor Airframe - main components which carry all the loads Bolt (nut) - joining member consisting of head and stem Aisle using a nut to tighten it - passage in passenger cabin between rows of chairs Bonding or adhesive bonding - method of joining using adhesive material Allowable stress (polymeric material with sufficient strength to - maximum stress level allowed in a structure transfer load) (so that it does not deform plastically or break) Brace Alloy - strengthening wire to support a structure, - the combination of several metal components generally loaded in tension Bracket Chord line - small fitting or support to attach system parts - an imaginary line jointing the leading and trailing edge of a wing section Brake - system attached to the wheels to slow down Cockpit or stop the airplane when on the ground - place where pilots fly the airplane Buckling Composite - out of plane bending, followed by crushing of - containing more than one component (in material under compressive loads particular materials containing a mixture of plastics and metal, or fibre reinforcements) Bulkhead - a panel separating areas in the structure Compression - stress or force that tends to push material together C Compressor Cabin - part of the jet engine where the air coming - the lace in the airplane where passengers form the inlet is brought to a higher pressure (payload) stay during the flight Controls Camber - instruments to control the aircraft: change the - the curved line precisely between the upper position of the control surfaces and the and lower skin of an airfoil propulsion Canard Corrosion - an arrangement of foreplanes and win, rather - attack of the material by an unwanted than the conventional wing and horizontal chemical reaction (oxidation) tailplane Cowling Cantilever - the covers around the engine - a beam supported only at the end Cruising flight, cruise Centre of gravity - the steady, stationary part of the flight when - point of balance of the mass of the aircraft the airplane is not landing starting or (component) performing a manoeuvre Centre of pressure Cut out - the centroid of the pressure distribution - removing of material, opening in skin or structure Centre-line of aircraft - line connecting geometric middle points of cross sections of the aircraft structure D Centre wingbox Deflection - central part of the wing which is located - change of the position of the control surface inside, right under or right above the fuselage Delta wing Centrifugal force - a wing in a triangular planform - a resulting force by spinning a mass around Dihedral Clips and Cleats - wing in a v-shape - small angles or simple sheet metal parts for (shear) connection of various parts Door - a hatch for letting people or cargo in and out Chord - the distance between the leading and trailing Double curvature edge of a wing section - structures that have different curvatures in two directions of various directions Doubler FAR - reinforcing sheet sheet against the skin - Federal Aviation Regulations, certification procedures and airwothiness standards of the Downwash US government (FAA) - a small air velocity component in the downward direction aft of the wing Fasteners - means for mechanically joining parts (bolted Drag and riveted joints) - a resisting force as a result of the motion of body through a medium Fatigue - failure, at relatively low stress levels, of Drain holes structures that are subjected of fluctuating and - holes in the structure to remove water cyclic stress accumulated during flight Fence - shield E Fin Elastic limit - vertical stabilizer, tailplane - point where elastic elongation changes in plastic elongation Finite element method - numerical method of calculation by Elevator discretisation a continuum into a finite number - control surface for pitch of parts (elements) Elevons Fitting - control surface for pitch and roll - generally heavily loaded part or fixture to attach system or other part to a structure Empennage - the rear section of the body of the airplane Flap with stabilisers - the movable part at the trailing edge of the wing which, when extended and / or deflected, Engines increase the lift - the power units for propulsion of the aircraft Flaperon Extrusion - the surface which combines the control - a forming technique whereby a metal in function of flaps and ailerons plastic condition at elevated temperature is force, by pressure, through a orifice Flight deck - place where the pilots fly the airplane F Foreplane - a horizontal stabilizing and control surface Fail safe forward of the wing (see canard) - principle of maintaining adequate performance after some degree of damage or degradation Flutter has occured - an oscillation caused by interaction between structural and aerodynamic effects Failure - plastic deformation or breaking of a structure Floor - lower surface of the cabin Fairing - non-structural transition part between Frame components to create an aerodynamic smooth - a hoop-shaped fuselage member which gives shape and low drag it its cross-sectional shape Fan (ducted – unducted) - propeller (shield – unshielded) Fuselage - the mainbody of the aircraft, airframe without the wings and the tail G Intake - the inlet of the engine to decelerate the flow Gust - turbulence Intercostal - part connecting two ribs for attachment of systems H Hardness J - the measure of material’s resistance to deformations by surface indentation or by JAR abrasion - Joint Aviation Regulations, certification procedures and airworthiness standards of the Hatch European Joint Aviation Authorities (JAA) - door for inspection or maintenance Joggles Heat treatment of metals - preformed flange of stringer to fit precisely - treatment to improve the material properties and follow thickness steps in structure (mechanical properties, formability, corrosion resistance) Joint - the connection between two parts High lift device - device to create higher lift L Hinge - a movable joint with one (or more) degree(s) Landing gear of freedom - the system (wheels, brakes, shock absorbers, struts, etc) on which the airplane can land Honeycomb - the core material, between face sheets of a Landing loads sandwich structure, with the shape of the six - the forces which are caused by landing in the sided wall shape made by the honeybee landing gear and back-up structure Hooke’s law Leading edge - the strain is equal to the stress divided by the - the front of the wing or tail plane Young’s modulus Lift Hoop stress - a force at right angles to a body’s motion - stress in a pipe wall acting circumferentially through the air, generated as a result of a (in a plane perpendicular to the longitudinal pressure difference between opposite surfaces axis of the pipe) and produced by the pressure of fluid or gas in the pipe Limit load - the high force which will be one time load the Horizontal stabilizer structure at which no plastic deformation - horizontal tailplane should occur Load I - the forces and moments acting on a structure ILS Longeron - instrument landing system - the main stringer in the fuselage or longitudinal beam Impact - collision of object onto a structure Lug - ear or connecting link Inertia - a body’s resistance to a change in its motion as a result of an applied acceleration M Panel - structural subassembly of skin and stiffening Mainframe elements - frame at which wing spar is connected to the fuselage Payload - the cargo and people that have to be Maintenance transported - to keep the plane in good condition for continued operation Pitch - rotation around the y axis of the aircraft, Manoeuvre distance between parts (e.g. rivet pitch) - movements of the aircraft deviating from the stationary flight (e.g. rolling,