Airframe Structures, Aeroplanes
Fuselage, wings, stabilisers, flight-control surfaces and nacelles/pylons.
Aeroplane structures, summary notes
- FUSELAGE (ATA 52/53/56): a semi-monocoque tube of frames, stringers and skin; on pressurised aircraft it is a pressure vessel sealed by forward and aft pressure bulkheads, with reinforced door and window cut-outs and floor beams carrying cabin/cargo loads.
- WINGS (ATA 57): built around spars (main load members) with ribs giving the aerofoil shape and stringers/skin resisting bending and torsion; the box between the spars is often an INTEGRAL ('wet') fuel tank using the structure itself.
- STABILISERS (ATA 55) and FLIGHT CONTROL SURFACES (ATA 55/57): lighter versions of wing construction; control surfaces are MASS-BALANCED (weight ahead of the hinge) and often aerodynamically balanced to prevent flutter and reduce hinge loads.
- NACELLES and PYLONS (ATA 54): support and streamline the engines, carry engine loads into the wing/fuselage and contain a firewall separating the hot engine zone.
- Windows, doors, access panels and floor structure are all reinforced cut-outs that must restore the interrupted load paths.
- ⚠ Exam trap: flight control surfaces are MASS-BALANCED (mass ahead of the hinge line) to prevent flutter; an integral 'wet wing' tank uses the sealed wing box structure as the tank, saving weight.
Why is a mass balance weight fitted forward of the hinge line on an aileron?
Without it, the surface's centre of gravity lies behind the hinge, so a wing bending/vibration can set up a self-exciting coupling between the surface's inertia and the aerodynamic forces, flutter, which can rapidly destroy the structure. A mass balance moves the surface's CG onto or ahead of the hinge line, breaking that coupling and preventing flutter.
Stress, strain & the tensile test
Aeroplane structures concept map
Airframe Structures, Aeroplanes
Aeroplane structures quiz
Airframe Structures, Aeroplanes, quiz
1. The main spanwise load-carrying members of a wing are the:
SparsRibsStringers only2. Ribs in a wing:
Give the aerofoil shape and support the skinCarry all bending loadStore fuel3. An integral ('wet') fuel tank uses:
The sealed wing box structure as the tankA separate rubber bladder onlyThe fuselage belly4. Flight control surfaces are mass-balanced to:
Prevent flutterAdd weight for CGImprove fuel flow5. On a pressurised fuselage, the pressure loads are contained by:
Forward and aft pressure bulkheadsThe wing sparsThe landing gear6. A pylon/nacelle (ATA 54):
Mounts the engine and contains a firewallStores fuelHouses the APU only7. A cut-out for a door or window must:
Be reinforced to restore the interrupted load pathBe left unreinforcedCarry no load8. The fuselage is generally of which construction?
Semi-monocoquePure truss with fabricSolid casting