Airframes 2 Flashcards
Airframe sections
Fuselage
Tailplane
Fin
Wing
Power plant
Undercarriage
Bending load
Tensile load tries to stretch
Compression load tries to shorten
Torsional load
Tries to twist structure
Long flat more susceptible than think rounded
Shear load
Sliding of one part over another
Common on rivets bolts and fasteners
Fuselage loading
Bending and shear loads during flight
Pressurisation adds tensile load
Also experiences torsion which results in further shear stress
Shear stress is two pieces bolted together wanting to go opposite directions
Fuselage construction types
Truss (internal load bearing structure covered by non load bearing skin)
Uses longerons, struts, fairing strips and bulkheads
Upper and lower horizontal members react to bending diagonal react to shear loads
Monocoque (no internal framework skin bears full load)
Compression buckling can be a problem
Semi monocoque (skin reinforced and stabilised by internal framework both load bearing)
Semi monocoque fuselage
Longerons and stringers horizontal help take bending loads frames vertical
Skin takes shear loads and some bending as well as pressurisation (tensile)
Fuselage shape
Square or rectangle means non pressurised
Circular can be pressurised
Wing configuration
Biplane (high and low wing)
Braced monoplane(one long wing with braces)
Cantilever (no bracing)
Wing loading cantilever
Wing subject to bending shear and torsional loads
Direction of bending changes whether on ground or in flight
Torsion results from distance between cog and cop
Fatigue
Function of load (how much force is applied) and cycles (number of times force is applied)
Signs of fatigue composite : delaminating and cracking
Signs of fatigue metal: cracking corrosion (rust)
Damage from heavy landing (aluminium alloy)
Stressed tyres
Scraping on wheel rim
Bent axles
Bent struts
Buckling at u/c attachments
Buckling if firewall
Tail strike
Operating outside flight envelope
Rippling of wing and fuselage skins
Buckling of internal structures
Composite damage
Vibration stresses
Minor impact loads (bugs)
Bird strike
Hangar rash
Mishandling
Fabric damage
Torn fabric
Worn fabric
Up damage
Mould
Wing construction
Typically 2 spars consisting of spar caps and spar webs (caps connect to skin web connects to caps)
Carry wing bending loads
Front and rear keel lift envelope in the middle
Loading of wing components
Webs carry shear loads
Stringers assist caps with bending loads and stabilise skin against buckling
Ribs maintain aero foil shape and transfer loads to spars
Skin transfers air loads onto ribs stringers and spars
Spar webs and skin form torsion box which resists twisting
Wing struts
Assist with bending load (allows wing to be lighter than cantilever)
Will always be in tension or compression
Struts increase drag
Flight controls
Primary
Similar to wing construction but with one spar
Secondary
Flaps and trim tabs
Tertiary
Slats etc
Bell crank
Lever who’s two arms form a right angle
Decreases friction and stress on wiring turning corner
Ground steering
Steerable or castoring
Da40 castoring
3 types of braking system
Independent: hydraulic pressure directly proportional to force applied by pilot (for light ac)
Boosted: additional hydraulic pressure from main system boosts brake power
Power brake: brake control valve and hydraulic pressure from main system regulated by pilot force
