construction methods of · pdf file02.10.2016 · mempertahan bentuk struktur....

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.

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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)

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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).


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 .


Kekurangan utama (Disadvantages) – adalah:

• Bentuknya tidak aerodinamis (non-streamlined shape).

• Bobot nya – berat.

Keuntungannya (Advantage) – lebih kaku / kokoh.


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;

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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

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World War - I:

•Biplane

•open cockpits

• radial engines

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•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.

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•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).

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Stressed – Skin Construction

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• 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.

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•Aluminum skin

•1920s and 30s :

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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 :

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(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:

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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.

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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.

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•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.



• 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

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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)

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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.


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


SPAR

1. resist bending and axial loads

2. form the wing box for stable torsion resistance


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.


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.


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.

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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)

http://en.wikipedia.org/wiki/File:H2A..jpg

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) .

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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


Structural Members


• 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


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.

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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.

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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 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


• 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

http://en.wikipedia.org/wiki/File:Fuselage_Piper_PA18.JPG

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:

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:

construction methods of · pdf file02.10.2016 · mempertahan bentuk struktur....

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