The document discusses the different types and functions of aircraft fuselages. It describes how fuselages form the main body of an aircraft and house key components. There are three main types of fuselage structures: frame, monocoque, and semi-monocoque. Frame structures use a series of pipes but are heavier, while monocoque structures rely on the skin to take all loads but are fragile. Semi-monocoque fuselages provide a balance by sharing loads between the skin and internal structures. The document also outlines features like windows, doors, engines mounts and shapes that fuselages can take.

2. 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

4. Types
Frame 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

5. Types
 Heavier if shape
altered
 Covered with
fabric, fiberglass,
aluminum,
Kevlar e.t.c.

6. Types

7. Types
Monocoque 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

8. Types
 Inherently heavy and fragile by design, not used in
airliners.

9. Types
Semi-Monocoque structure:
 Loads shared by skin,
frames, stringers and
formers
 Tolerant to damage
 Good strength to
weight ratio
 More redundancy then
monocoque construction

10. Types
Reinforces shell structure:
 Best redundancy in shell structure
 Reinforced windows, doors and hatch attachment
points
 Longerons added for further load distribution, prevent
crack propagation

13. Joining methods
Riveting:
 Old process, time
consuming, more drag
Bonding:
 Using an adhesive to attach metallic parts

14. Joining methods
Milling:
 To remove unnecessary material
 Material retention adds rigidity

15. Joining methods
Etching:
 Using chemicals to remove material or create design or
shapes in billets

16. 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

18. 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

19. Blow out bungs
 Plastic blowout bungs to equalize pressure in case of
decompression

20. Windows
Flight 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

21. Windows (flight deck)
 Better ground and forward visibility
 Reduction in size of screen windows
 Sheds water better
 Reduces impact force
 Reduces pressure loads

22. Windows (flight deck)
Stepped:

23. Windows (flight deck)
Exception:

24. Windows
Direct vision window:
 For maintaining clear vision
 Opened from inside
 Can also be used as
emergency exits

25. 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

26. Windows

27. 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

28. Doors

29. Doors
Some 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

30. 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

31. Sealing
 Pressurization costs fuel/energy
 Every item passing through a hole is sealed

32. 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

33. Spar attachment
 The strongest part of fuselage where wings are
attached
 All flight loads converge at this point

34. Fuselage shapes
 Streamlined tapering design
 Suitable undercarriage/fuselage
for smaller payloads

35. 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

36. Fuselage shapes
Jet engine:
 With its advent fuselage became cylindrical with rounded
nose and a tapered tail
 Advantages:
 Easy manufacturing
 Lower operating costs

37. Fuselage shapes
 Better power to weight ratio
 Greater cargo and passenger capacity
 Easier loading and unloading of aircraft

39. Fuselage shapes
Tricycle undercarriage:
 Upward tapering tail till reaching the tip of tailcone
 Top of fuselage remains unchanged

41. Tail bumper:
 For protection during
rotation
 Fixed or retractable

42. Fuselage mounted engines
 Front mounted engines act as a tractor, pull aircraft
 Support frame takes vibrations and engine loads

43. Fuselage mounted engines
 Rear bulkhead mounted act as pusher

44. Fuselage mounted engines
 Jet engines can also be mounted in fuselage, usually
reserved for combat aircraft

45. 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

46. Fuselage mounted engines