Fuselage structures
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Transcript of Fuselage structures
Introduction
Forms main body of aircraft to which wings, tail plane, engines and gears are attached
In modern aircraft forms a tube structure housing flight deck, pax cabin, hold and equipment
Also acts as a pressure hull in pressurized aircraft
TypesFrame structure:
A box frame made up of a series of vertical, horizontal, diagonal and longitudinal tubular steel pipes
Design produces a square profiled fuselage
Used in old aircraft and light modern aircraft
Frame takes up all the loads
TypesMonocoque structure:
Skin takes up all flight and ground loads and shape gives structure its rigidity
Any damage to skin directs effects its load carrying capacity
Complications in designing doors windows and hatches
TypesSemi-Monocoque structure:
Loads shared by skin,
frames, stringers and
formers
Tolerant to damage
Good strength to
weight ratio
More redundancy then
monocoque construction
TypesReinforces shell structure:
Best redundancy in shell structure
Reinforced windows, doors and hatch attachment points
Longerons added for further load distribution, prevent crack propagation
Joining methodsRiveting:
Old process, time
consuming, more drag
Bonding:
Using an adhesive to attach metallic parts
Pressure bulkheads Pressure cabin terminates at the front and rear
bulkheads
Usually dome shaped for better pressure distribution
In some designs floor part of pressure hull, un-pressurised hold in this case
Cabin floors
In modern designs are not used as bulkheads
Series of panels attached to supporting beams of aircraft
Honeycomb panels
used for best
weight to strength
ratio
WindowsFlight deck:
Heated for de-icing
JAR approved for bird strikes
Laminated like car windscreens
Stepped nose profile used in most subsonic airliners
Helps in:
Aerodynamic profiling
Windows (flight deck)
Better ground and forward visibility
Reduction in size of screen windows
Sheds water better
Reduces impact force
Reduces pressure loads
WindowsDirect vision window:
For maintaining clear vision
Opened from inside
Can also be used as
emergency exits
Windows Passenger cabin windows:
Form a part of pressure shell of fuselage
Reinforced surrounding structure
Windows fitted from inside and larger then apertures
Two panes with air filled gap in between them
Doors Commonly plug type doors used in commercial
aircraft
Closed from inside with locking pins engaging into door frame
Open by pulling back on inside and turning/sliding sideways
DoorsSome requirements are:
Must not be located near propellers
Must be able to open with people surrounding it
In emergency, external handle must be able to unlock door
Must open from both sides, handles to be flushed to skin
Doors
Must be a visual indication of doors being secured and locked, both externally and internally. E.g. flushing handle on outside, warning light on the crew warning panel
Must not jam in emergencies
Must b a means of safe-guarding against inadvertent operation in flight
Seat mountings
Must withstand loads e.g.
Forward 3.0g
Upward 9.0g
Downward 6.0g
Sideward 4.0g
Seat mountings attached to crossbeams below floor structure
Spar attachment The strongest part of fuselage where wings are
attached
All flight loads converge at this point
Fuselage shapes Fuselages became more
cylindrical to carry more
payloads
Engines had to be added
which added weight
penalties
Large piston engines
give diminishing returns
Fuselage shapes Jet engine:
With its advent fuselage became cylindrical with rounded nose and a tapered tail
Advantages:
Easy manufacturing
Lower operating costs
Fuselage shapes
Better power to weight ratio
Greater cargo and passenger capacity
Easier loading and unloading of aircraft
Fuselage shapesTricycle undercarriage: Upward tapering tail till reaching the tip of tailcone
Top of fuselage remains unchanged
Fuselage mounted engines
Front mounted engines act as a tractor, pull aircraft
Support frame takes vibrations and engine loads
Fuselage mounted engines Jet engines can also be mounted in fuselage, usually
reserved for combat aircraft
Fuselage mounted engines
For twin engine aircraft, engines can also be mounted to sides of fuselage
Mounted on stub wings
Reduces drag and cabin noise as compared to wing mounted aircraft
But early onset of stall