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Construction Methods of:
a) Stressed-skin Fuselage,
b) Formers, Stringers, Longerons, Bulkheads, Frames, Doublers, Struts, Ties, Beams,
Floor Structures, Reinforcements,
c) Methods of Skinning,
d) Wing and Empennage Attachements,
Tipe Konstruksi Pesawat Udara Dua Tipe/Jenis Utama dari Konstruksi Struktur : 1. Rangka Batang (Truss) atau Kerangka (Framework)
– umumnya digunakan untuk pesawat terbang ringan, bermesin-tunggal (single–engine models), fuselage tidak bertekanan (unpressurized fuselage).
2. Stressed-skin Structure – (struktur kulit yang menahan tegangan /cangkang bertekanan):
a. Monocoque (Bhs Perancis: hanya cangkang / single shell only)
b. Semi-monocoque (cangkang yang diperkuat /-kaku atau stiffened shell)
c. Reinforced Shell Structure.
2
Types of Aircraft Construction
Two Main Types of Construction in use:
1. Truss or Framework Structure -Type of Construction, generally used for light, single – engine models, unpressurized fuselage, aircraft.
2. Stressed-skin Structure – Type of Construction:
a. Monocoque (single shell only)
b. Semi-monocoque (stiffened shell)
c. Reinforced Shell Structure.
3
Aircraft Structures Construction
• TRUSS-TYPE STRUCTURES
• Had struts and wire-braced wings
• Occupants sat in open cockpits
• Cockpits fabric-covered
• STRESSED-SKIN STRUCTURES (skin memikul beban)
• All of the structural loads are carried by the skin.
• Thin wood skin
• Or aluminum-alloy sheets (skins)
4
Konstruksi Rangka Batang (Truss or Framework Construction)
Konstruksi Rangka Batang (Truss or Framework Construction)
Occupants sat in open cockpits
Struktur konstruksi tipe TRUSS / FRAME - terdiri dari:
• 4 (empat) buah Longeron – yang ditempatkan di keempat sudut struktur – gunanya untuk memikul sebagian besar beban-beban Tekan (compressive) dan Tarik (tensile).
• Cross members/bracings – batang yang menyilang secara diagonal – memisahkan longeron, ideal-nya batang diagonal terutama memikul beban Tarik (Tension), kenyataannya ia juga mengalami beban Tekan/Kompresi (Compression).
Konstruksi Rangka Batang (Truss or Framework Construction)
Komponen truss /rangka-batang ..... (- samb) :
• Frame – batang vertikal & horizontal mempertahan bentuk struktur.
• Fuselage truss mempunyai cross-bracing tipe N, X, atau W (warren).
• Truss /framework (primary structure) dibungkus dengan pembungkus (cover) dari bahan (fabric) dari katun atau linen gunanya untuk memberi bentuk aerodinamis. Bungkus ini – merupakan struktur sekunder .
Konstruksi Rangka Batang (Truss or Framework Construction)
Konstruksi Rangka Batang (Truss or Framework Construction)
Kekurangan utama (Disadvantages) – adalah:
• Bentuknya tidak aerodinamis (non-streamlined shape).
• Bobot nya – berat.
Keuntungannya (Advantage) – lebih kaku / kokoh.
Konstruksi Rangka Batang (Truss or Framework Construction)
Definisi :
Stressed Skin Structure :
A type of aircraft structure in which all or most of the stresses are carried in the outside skin.
• A stressed skin structure has a minimum of internal structure.
Struktur Kulit di Tegangkan/Ketatkan : adalah - Tipe/jenis struktur pesawat terbang
dimana seluruhnya atau sebagian besar tegangan dipikul oleh kulit luar.
Definisi :
Definisi berikut ini akan diterangkan kemudian :
Monocoque Structure ;
Semi-monocoque Structure ;
Reinforced Shell Structure;
1/15/2012 13
Structure of early machines:
•Wings of bent wooden ribs covered with fabric
•Body of open Frameworks of wood strips lashed
together with wire
•Landing gear were skids
1/15/2012 14
World War - I:
•Biplane
•open cockpits
• radial engines
1/15/2012 15
•metal tube Truss
construction
•Welded thin-walled
metal tube
• covered with fabric
• lighter weight and
stronger
World War - I:
Structure of early machines:
•1st airplane – made with truss structure of wood or
bamboo, and
•The lifting and control surfaces were covered with
cotton or linen fabric.
•This structure was lightweight, but difficult to
streamline.
•When aircraft speeds increased that the
streamlining became important.
1/15/2012 17
•1920s and 30s: •Stressed-Skin Construction
Lockheed airplane – used the molded plywood monocoque structure
Fig.1-3 :
• Pesawat terbang yang pertama kali menggunakan struktur kulit yang memikul beban (stressed-skin) – lapisan luar (skin) terbuat dari kayu tipis yang dibentuk dengan cetakan beton (concrete molds).
18
Stressed – Skin Construction
1/15/2012 19
• 1920s and 30s :
Sheet - Metal Aircraft Construction • Pure Aluminum alloy is weak. •During WW-I, Germans discovered that to increase Al- strength without increasing its weight, was by alloying it with Copper, Manganese, and Magnesium. •This new alloy was called – Duralumin, and it was the forerunner or the high-strength and lightweight alloys that are used in the aircraft construction today.
Duralumin : is the name for the original alloy of Aluminum (Al),
Magnesium (Mg), Manganese (Mn), and Copper (Cu). Duralumin – is the
same as the modern 2017 aluminum alloy.
1/15/2012 21
•Aluminum skin
•1920s and 30s :
1/15/2012 22
I. Evolution of Aircraft Structures
II. Types of Aircraft Structures:
A. That Produce Lift
B. That Produce Control
C. That Modify Lift
D. That Aid Control
E. That Hold People
F. That Support the Aircraft (Ground)
G. That Hold the Powerplant
H. Rotorcraft
•Aluminum
structure
•MONOCOQUE
construction
•1920s and 30s :
23
(Bhs Perancis) Monocoque : artinya Hanya cangkang (shell only)
Rancangan / design monocoque hanya memakai kulit yang diketatkan atau cangkang tertekan (stressed skin) untuk menahan hampir semua beban-beban primer (twisting dan bending). Struktur ini dapat sangat kuat tetapi tidak dapat menahan penyok atau deformasi pada permukaannya. Ciri khas ini dapat dengan mudah diperagakan oleh kaleng aluminium tipis dari kemasan minuman ringan: y.i. Dengan memberikan gaya yang cukup besar pada ujung-ujungya tanpa menimbulkan kerusakan.
MONOCOQUE – Type of Fuselage Construction
MONOCOQUE Type of Fuselage Construction:
24
Tetapi, jika sisi dari kaleng penyok atau retak sedikit saja, kaleng tsb akan rusak (collapse) dengan mudah.
Pure - Monocoque Structure Cangkang Telor
MONOCOQUE
• In this method, the exterior surface of the fuselage is also
the primary structure.
•A typical early form of this was built using molded plywood.
•A later form of this
structure - uses fiberglass
cloth impregnated with
polyester or epoxy resin,
instead of plywood, as the
skin.
25
Monocoque Fuselage Construction
Konstruksi Monocoque murni – terutama terdiri dari : Skin, Formers assy, dan Bulkheads.
Formers dan Bulkheads memberikan bentuk bagi fuselage, tapi SKIN – pemikul beban / tegangan (stresses) utama.
26
1/15/2012 27
•Since 1930s : •SEMI-MONOCOQUE construction
Stressed-Skin Construction – is widely used because:
– It has a high strength per weight ratio
– It provides a large unobstructed internal volume
– It (the tube) provides the largest volume per surface area ratio possible
– It can be easily formed into streamlined shapes.
Stressed-Skin Construction
MONOCOQUE structures (hanya cangkang): • Pada konstruksi tipe monocoque – skin memikul
seluruh beban /stress, dan tidak ada penopang didalamnya (internal supports), seperti tabung (tube).
• Skin cukup tebal - terbuat dari konstruksi “sandwich”. Contoh: • De Havilland Mosquito (PD-II pesawat fighter bomber
milik Inggris) – konstruksi sandwich kayu balsa - dan - plywood (kayu lapis);
• Modern high performance Sail planes; • Helicopter Rear Fuselage, Sail planes dan pesawat
modern lainnya – fiber glass & carbon fiber composites.
Stressed-Skin Construction
Stressed-Skin Construction
• Kebanyakan pesawat udara modern – terdiri dari konstruksi struktur berdinding tipis (thinned walled structures or shells).
• Struktur tipe Konstruksi Monocoque atau Semi-monocoque.
MONOCOQUE structures:
Unstiffened shells.
Must be relatively thick to resist bending, compressive, and torsional loads.
Virtually no internal framework
31
Definitions . . .
Definitions . . .
SEMI – MONOCOQUE structures:
• Constructions with stiffening members that may also be required to diffuse concentrated loads into the cover.
• More efficient type of construction that permits much thinner covering shell.
BEDA - Struktur Konstruksi MONO - & SEMI-MONOCOQUE
• Monocoque • Virtually no internal framework • (Nyaris tidak ada kerangka didalamnya)
• Semi-monocoque
• Internal arrangement of formers and stringers is used to provide additional rigidity and strength to the skin.
• (Susunan dalam dari formers dan stringers digunakan untuk memberikan tambahan kekakuan dan kekuatan kepada skin)
33
34
Monocoque Construction Semi-monocoque Construction
BEDA - Struktur Konstruksi MONO - & SEMI-MONOCOQUE
Definitions . . .
REINFORCED SHELL structure : • This is the most commonly used structure in modern all-metal aircraft.
•The shape is provided by Bulkheads, Formers, and Stringers, but •The structure is reinforced with Longerons that help carry the Loads. •A sheet-metal skin riveted over the structure – carries a major portion of the flight loads.
SEMI – MONOCOQUE structures: • Pada konstruksi tipe ini – skin memikul sebagian beban
/stress, dan diberi penguat/pengaku didalamnya yang ikut memikul beban.
SKIN dari semi-monocoque di-perkuat / perkaku (stregnthened / stiffened) oleh:
(a) LONGERONS (4 buah) – arah memanjang (longitudinal), memberi kekuatan bending dan ketahanan (resistensi) terhadap beban kompresi (tekan).
(b) STRINGERS (kecil-kecil & banyak) – penguat arah memanjang,
(c) FRAMES (untuk Fuselages) , RIBS (wing, tail-units) – arah melintang /transverse.
(d) BULKHEADS – arah melintang/transverse.
Stressed-Skin Construction
Function of Aircraft Structures
GENERAL The structures of most flight vehicles are thin walled
structures (shells) • Resists applied loads (Aerodynamic loads acting on
the wing structure)
• Provides the aerodynamic shape
• Protects the contents from the environment
Function of Aircraft Structures: Part specific
SKIN • Reacts the applied torsion and shear forces • Transmits aerodynamic forces to the longitudinal and transverse supporting members • Acts with the longitudinal members in resisting the Applied bending and axial loads • Acts with the transverse members in reacting the hoop, or circumferential, load when the structure is pressurized.
RIBS AND FRAMES 1. Structural integration of the wing and fuselage
2. Keep the wing in its aerodynamic profile
Function of Aircraft Structures: Part specific
SPAR
1. resist bending and axial loads
2. form the wing box for stable torsion resistance
Function of Aircraft Structures: Part specific
Stiffener or Stringers
1. Resist bending and axial loads along with the skin
2. Divide the skin into small panels and thereby increase its buckling and failing stresses
3. Act with the skin in resisting axial loads caused by
pressurization.
Function of Aircraft Structures: Part specific
All of the above elements (spar, stringers, ribs) are attached to aircraft skin by:
Riveting; Bonding; or Integrally Machined.
Heavy Frames or Ribs are fitted to certain areas of the fuselage or wing – where there are additional stresses /loads, e.g:
• Main and Nose Gear attachments; Front and Rear Spars attachments; engines, Wing-Fuselage attachments, etc.
Function of Aircraft Structures: Part specific
Structural Members
(Bagian-bagian struktur lain-nya) :
TIES (Strap): komponen struktur yang
dirancang (designed) untuk memikul beban tarik (tensile loads/stresses).
• Biasanya berupa batang pejal (solid rod) yang berpenampang kecil.
• Pada pesawat modern ties jarang dipakai lagi, jadi agak sulit ditemui.
1/25/2011 45
Structural Members (Bagian-bagian struktur lain-nya)
Contoh TIES (Strap):
• Yang bagus adalah kabel kontrol (persisnya bukan struktur),
• Cross-bracing (batang penyanga) pada struktur yang non-monocoque (di pesawat jaman dulu).
1/25/2011 46
A hurricane tie used to fasten a rafter to
a stud (bangunan)
Structural Members
(bagian-bagian struktur lain) :
STRUTS atau Kolom : dirancang
terutama untuk memikul beban kompresi / tekan.
Bila dibebani Strut akan cenderung melendut (bend) atau menekuk (buckle), kecuali ia sangat pendek (maka akan menahan beban tekan murni /pure compressive loads) .
1/25/2011 47
Structural Members
(Bagian-bagian struktur) :
STRUTS atau Kolom
Bila strut harus panjang – maka penampang strut harus besar, utk menahan lenturan (bending). Ini artinya ada “weight penalty “
Contoh:
Landing gear Strut,
Floor support strut – A320
Contoh-contoh : Strut
Compression strut on Piper Pawnee (low-wing aircraft)
Tension strut on Shorts 360 (high-wing aircraft)
STRUTS - (cont’d) :
Examples : landing gear strut; floor support struts. Struts – are designed with most of their metal on
the outside. For struts that could bend in any direction – they
are usually of hollow tubular cross-section (i.e. Yacht masts (tiang kapal), Push-pull control rods, etc.).
Struts – that are designed to bend in one (1) direction only , are made in the form of I–section beams with most of the material on the outside edges of strut.
Structural Members
(bagian-bagian struktur lainnya) :
Nosewheel oleo strut on Su-30MKI aircraft
Contoh-contoh : Strut
Landing gear with oleo strut and scissor- or torque links
Structural Members - Strut
(bagian-bagian struktur lainnya) :
Structural Members
(bagian-bagian struktur lainnya) :
• Beams : dirancang untuk menahan beban bending pada satu arah.
– Contoh yang paling baik adalah – Spar dari wing.
– Wing spar harus menahan lendutan keatas (upward bending), akibat Gaya Angkat, selama penerbangan, dan lendutan kebawah (downward bending) akibat Gaya Berat-nya ketika didarat.
1/25/2011 53
Structural Members
(bagian-bagian struktur lainnya) :
Structural Members - Strut
Struts on the undercarriage , wings, and Tailplane of an Antonov An-2 biplane.
Floor Structures:
On Small aircraft – floors are :
• Simply an Al alloy panel riveted to horizontal cross members, and
• Strengthen locally to support seats, controls and cockpit equipments,
• May be painted black to reduce internal glare, and on some a/c it may be carpeted. The carpet either being a close fit, or fitted with press studs, or bonded to the floor panel.
On Larger aircraft – The Floor – : • Is the structure separating the Cabin area from the
Baggage area or Cargo hold. This means that – it may nor have additional supports over much of its width from wall-to-wall.
• Subjects to considerable bending stress. • May be made of Aluminum alloy or Carbon Fiber (CF)
composite or metal honeycomb. This gives the floor reasonable thickness ( to resist bending loads) and to support it on cross-members (beams) usually made of Aluminum alloy.
• Usually of I – section, or made up of : top & bottom members separated by web members.
Floor Structures:
Floor Structures:
Transport Passenger Flooring
For Passenger aircraft – The floor :
• Will house seat rails, and have provision for the fitting of carpets.
On Pressurized a/c – the floor area/side wall area contain pressure equalization holes/vents (dado panels), to allow pressure to equalize between the Pax area and cargo bay – area.
• Has emergency lighting fitted to assist pax crawling to an exit – in a smoke filled cabin (some a/c have emergency lighting is fitted to isle seats.
Floor Structures:
Pressure equalization holes/vents (dado panels)
Fitted to the underside of Floor Structure :
• Equipment cables, ducting, control cables, pipelines, electrical cables, smoke detectors, and fire proofing (mandatory for cargo bays).
Floor Structures:
1/25/2011 63
AIRCRAFT
MAJOR COMPONENTS (Bagian/komponen Utama Pesawat Udara)
Fixed Wing (Sayap Tetap)
Airframe Units / 5 (five) - Major Components :
• Fuselage
• Wings
• Stabilizers
• Flight control surfaces
• Landing gear
64
Airframe Units/Major Components :
Elevator
Horizontal Stabilizer
Rudder
Vertical Stabilizer
Aileron
Flap
Cowling
65
Gambar 1. Struktur Pesawat Bermesin-Tunggal, propeller-driven a/c.
Bagian Umum Pesawat Udara
1/25/2011 66
Gambar 2. Struktur Pesawat Bermesin-Ganda, Turbine-powered
1/25/2011 67
ROTORCRAFT
MAJOR STRUCTURAL
COMPONENTS (Bagian/komponen Utama Pesawat Sayap
Berputar)
Rotary Wing (Sayap Berputar)
Bagian Utama Helikopter (Rotorcraft Major Components)
Struktur Helikopter (Rotary-wing aircraft = Rotorcraft) terdiri dari 4 (empat) – Bagian Utama :
1. Fuselage /Body (Badan pesawat)
2. Main Rotor & related Gear-Box
3. Tail Rotor (pada helikopter dengan single main rotor)
4. Landing Gear (Roda Pendarat)
Main rotor – means the rotor that supplies the principal lift to a rotorcraft.
1/25/2011 68
Airframe of a Helicopter
1/25/2011 69
Gambar 3 : The major components of a helicopter (w/ a single main rotor) are: the Cabin, Airframe, Landing Gear, Powerplant, Transmission, Main Rotor System, and Tail Rotor system.
Location of Major Helicopter Components:
1/25/2011 70
Gambar 4. Komponen Utama Helikopter.
Structures
71
Structures
• Wing Construction Truss-type
72
Structures
• Stressed-skin Wing Construction
73
Cantilever Wing
Figure 1-11. Modern airplane uses a cantilever wing construction, which eliminates the need for struts to support the main wing.
74
Methods of Machining Wing Skin
1. Chemical Milling ,
2. Electro-chemical Machining.
1) Chemical Milling : – A slab of Al alloy is treated with an acid-resisting coating
where the full thickness of the material is needed.
– The slab is the immersed in a vat of acid and unneccary aluminum is chemically eaten away.
– Chemical milling is good for quickly removing large amounts of material, but when complex shapes or deep grooves must be cut, 2nd process may be used.
75
2) Electro-chemical Machining :
– After the skin is immersed in a salty electrolyte, an electrurrentode-cutting tool made from soft copper (Cu) and carrying a large amount of electrical current, is passed near the surface of the skin.
– This electrolytic process eats away the metal at a rapid rate w/o actually touching the metal, leaving no tooling marks that could cause stress concentration points where cracks could form.
• Both fabrication processes produce integral / built-in stringer to skin.
76
Stressed-Skin Wing Construction
Control Surface Construction
77
Fig. 1-13. Vertical and Horizontal surfaces made of welded thin-walled tubing are covered with cloth or sythetic fabrics.
Control Surface Construction
• Control Surface Flutter
• Control Surface must be mass balanced so that their center of gravity does not fall behind their hinge line.
• Flutter - is a primary design consideration for any
control surface. • It occurs when out-of-balance condition causes a
contol surface to oscillate in the airstream, typically increasing in frequency & amplitude until the control surface fails catastrophically.
78
Control Surface Construction
• Flutter – is caused by the interaction of aerodynamic forces, inertia forces and elastic properties of the surface or structure and can lead to a catastrophic failure of the structure.
• Poorly maintained aircraft, particularly those with excessive control surface backlash (play) or flexibility may mean that flutter could occur at speed below the limit airspeed.
• Flutter of the wing may be prevented by using the engine as mass balances, placing them on pylons forward of the wing Leading Edge.
79
Wing-pod (pylon) mount nacelle
The engine as mass balances, placing them on pylons forward of the wing Leading Edge.
Pylon (wing-pod)
80
TYPES OF FUSELAGE CONSTRUCTION
1. Truss Fuselage construction
• Pratt truss
• Warren truss
2. Stressed-skin Structure
• Monocoque
• Semi - Monocoque
3. Pressurized Structure
81
82
• Axial Stress. Axial or Longitudinal Stress are set up in the fuselage of aircraft when pressurized and tend to elongate the fuselage.
• Hoop Stress. Hoop, or circumferential, Stresses are set up in addition to axial stress and tend to expand fuselage cross section area. The internal pressure (radial & all directions) that set up these stresses can be as high as 65.5 KN/m² (or 9,5 psi). (ref. Airbus a/c)
Konstruksi Fuselage
d) WING AND EMPENNAGE ATTACHMENTS
Wing – Fuselage Intersections / Attachments :
Configurations of Wing (Mainplane) and Fuselage Intersection:
(a) High Wing: – wing-to-fuselage joined by Truss Links ;
– Carry – through Section
(b) Low Wing: Carry – through Section
(c) Mid Wing: Carry – through Section
(d) Mid Wing : integral unit of fuselage bulkhead and wing spar.
Wing – Fuselage Intersections
85
(a) High wing (b) Low wing
(c) Mid-wing (d) Mid-wing
Figure: The vertical location of the wing relative to the fuselage
Empennage – Aft Fuselage
Intersections
Configurations of Horizontal Stabilizer (Tailplane) and Fuselage Intersection:
(a) Permanently fixed Mount
(b) Variable – incidence Mount
(c) All-moving Tail (Flying Tail) Transport
(d) Flying Tail or Taileron Mount – Fighter a/c
Horiz. Stab – Aft Fuselage Intersections
Fig. 11.6.1 Configurations of Horizontal Stabilizer (Tailplane) and Fuselage Intersection:
Horiz. Stab – Aft Fuselage Intersections
Fig. 11.6.1 Configurations of Horizontal Stabilizer (Tailplane) and Fuselage Intersection:
Configuration of Aft Fuselage and Vertical Stabilizer (Fin) Intersection :
(a) Folding Tail
(b) Removable Tail
(c) Fixed Tail : – Case I – Tail-box Front and Rear Spar terminated
at Aft Fuselage Bulkheads;
– Case II – Tail-box terminated outside of Aft Fuselage Skin.
Empennage – Aft Fuselage Intersections
Vertical Stabilizer – Aft Fuselage Intersections
Fig. 11.6.3 Configurations of Vertical Stabilizer (Fin) and Aft Fuselage Intersection:
Vertical Stabilizer – Aft Fuselage Intersections
Fig. 11.6.3 Configurations of Vertical Stabilizer (Fin) and Aft Fuselage Intersection: