Jumat, 25 Desember 2009

de Havilland Comet Long-Range Jetliner






DESKRIPSI
Salah satu cerita tragis untuk pesawat jet adalah de Havilland Comet yang tidak beruntung. Dibuat di Inggris yang memimpin teknologi jet setelah PD II, de Havillang mengembangkan dan menerbangkan pesawat jet komersial pertama pada 1949, beberapa tahun sebelum rivalnya Boeing di Amerika. Dikenal sebagai D.H.106 Comet, pesawat ini menggunakan empat mesin turbojet baru de Havilland Ghost 50 yang dipasang di akar sayap bagian depan yang similar dengan pesawat komersial saat itu.

Karena pesarat ini merupakan representasi dari penerbangan komersial canggih revolusioner, Comet telah melalui berbagai seri panjang penerbangan ujicoba dan sertifikasi selama 3 tahun selanjutnya. Terdapat 500 jam terbang untuk pelatihan awak dan penerbangan uji coba termasuk penerbangan di atas laut, operasi di daerah tropis dan takeoff altitude tinggi.

Setelah sukses dalam pengujian tanpa banyak kesulitan, pesawat ini mulai menerima ijin untuk operasi komersial pada 1952. Kemunculan permasalahan pertama terjadi setahun setelah operasi komersial dimulai ketika Comet secara misterius mengalami kecelakaan tidak lama setelah take off pada 2 Mei 1953. Dua kecelakaan serupa terjadi pada 1954, memaksi otoritas Inggris untuk melakukan investigasi secara penuh. Setelah beberapa bulan, pengujian kembali dilakukan terhadap pesawat ini untuk menyelidiki penyebab kecelakaan misterius ini.

Jawabannya akhirnya didapat, penyebabnya karena adanya submerged (penggabungan) sebuah tangki air di badan pesawat, dan kondisi bertekanan dan tak bertekanan secara berulang-ulang dan terus menerus pada penerbangan. Setelah beberapa ribu penerbangan, kondisi ini menyebabkan keretakan yang menyebar pada jendela berbentuk kotak di dalam kabin penumpang. Keretakan ini akan mencapai ukuran kritis yang pada akhirnya dapat menghancurkan pesawat.

Seluruh Comet yang masih beroperasi dan dalam masa pembuatan akhirnya diterlantarkan atau mengubah bentuk jendelanya dengan sudut melingkar untuk mengurangi masalah keretakan ini. Akan tetapi, perlu empat tahun untuk pesawat ini mendapatkan kembali sertifikasinya dalam pelayanan komersial. Pada saat itu, pesawat Comet 4 yang lebih canggih telah beroperasi dan dilengkapi dengan mesin yang lebih baik, penambahan kapasitas bahan bakar dan kabin yang lebih panjang untuk penambahan penumpang.

Akan tetapi, empat tahun terhentinya operasi Comet membuat konsumennya beralih ke rival Boeing 707 dan Douglas DC-8. Hanya sekitar 90 Comet yang dipakai oleh operator komersial dan sebagian besar diganti dari pengoperasian pada 1980an. Beberapa pesawat tambahan digunakan untuk Militer, tetapi hanya Nimrod, turunan dari Comet, yang tetap dipakai. Jika Comet tidak mengalami masalah, mungkin Inggris akan tetap menjadi dominator dalam industri aviasi hingga saat ini.



HISTORY:
First Flight:
(Comet 1) 27 July 1949
(Comet 1A) 11 August 1952
(Comet 2) 27 August 1953
(Comet 3) 19 July 1954
(Comet 4) 27 April 1958
(Comet 4B) 27 June 1959
(Comet 4C) 31 October 1959
Service Entry:
(Comet 1) 22 January 1952 (freight service with BOAC)
(Comet 1) 2 May 1952 (passenger service with BOAC)
(Comet 4) 4 October 1958

CREW: 4 flight crew

PASSENGERS:
(Comet 1) 36 in three classes
(Comet 1A) 44 in three classes
(Comet 2) 44 in three classes
(Comet 3) 58 in three classes, 78 in two classes
(Comet 4) 56 in three classes, 81 in two classes, 109 in one class
(Comet 4B) 71 in three classes, 101 in two classes, 119 in one class
(Comet 4C) 79 in three classes, 101 in two classes, 119 in one class

ESTIMATED COST: (Comet 1) £250,000

DIMENSIONS:
Length:
(Comet 1) 93.78 ft (28.61 m)
(Comet 1A) 93.78 ft (28.61 m)
(Comet 2) 96.79 ft (29.53 m)
(Comet 3) 111.50 ft (33.98 m)
(Comet 4) 111.50 ft (33.98 m)
(Comet 4B) 117.90 ft (35.97 m)
(Comet 4C) 117.90 ft (35.97 m)
Wingspan:
(Comet 1) 114.83 ft (34.98 m)
(Comet 1A) 114.83 ft (34.98 m)
(Comet 2) 114.83 ft (34.98 m)
(Comet 3) 114.83 ft (34.98 m)
(Comet 4) 114.83 ft (34.98 m)
(Comet 4B) 107.83 ft (32.87 m)
(Comet 4C) 114.83 ft (34.98 m)
Height: 29.50 ft (8.99 m)
Wing Area:
(Comet 1) 2,023 ft2 (188.30 m2)
(Comet 1A) 2,023 ft2 (188.30 m2)
(Comet 2) 2,023 ft2 (188.30 m2)
(Comet 3) 2,121 ft2 (197.04 m2)
(Comet 4) 2,121 ft2 (197.04 m2)
(Comet 4B) 2,055 ft2 (191.30 m2)
(Comet 4C) 2,121 ft2 (197.04 m2)
Canard Area: not applicable

WEIGHTS:
Empty:
(Comet 4) 75,425 lb (34,210 kg)
(Comet 4B) 78,350 lb (35,540 kg)
(Comet 4C) 79,610 lb (36,110 kg)
Typical Load: unknown
Max Takeoff:
(Comet 1) 104,985 lb (47,620 kg)
(Comet 1A) 115,000 lb (52,160 kg)
(Comet 2) 120,000 lb (54,430 kg)
(Comet 3) 144,975 lb (65,760 kg)
(Comet 4) 162,000 lb (73,480 kg)
(Comet 4B) 157,875 lb (71,610 kg)
(Comet 4C) 162,000 lb (73,480 kg)
Fuel Capacity:
(Comet 1) 7,045 gal (27,300 L)
(Comet 1A) 8,100 gal (31,395 L)
(Comet 2) 8,100 gal (31,395 L)
(Comet 3) 9,805 gal (38,000 L)
(Comet 4) 10,440 gal (40,450 L)
(Comet 4B) 9,150 gal (35,460 L)
(Comet 4C) 10,440 gal (40,450 L)
Max Payload:
(Comet 1) 12,500 lb (5,670 kg)
(Comet 1A) 11,800 lb (5,350 kg)
(Comet 2) 13,500 lb (6,125 kg)
(Comet 3) 20,200 lb (9,160 kg)
(Comet 4) 20,280 lb (9,200 kg)
(Comet 4B) 24,100 lb (10,930 kg)
(Comet 4C) 24,100 lb (10,930 kg)

PROPULSION:
Powerplant:
(Comet 1) four de Havilland Ghost 50 Mk 1 turbojets
(Comet 1A) four de Havilland Ghost 50 Mk 2 turbojets
(Comet 2) four Rolls Royce Avon 503 turbojets
(Comet 3) four Rolls Royce Avon 523 turbojets
(Comet 4) four Rolls Royce Avon 524 turbojets
(Comet 4B) four Rolls Royce Avon 525B turbojets
(Comet 4C) four Rolls Royce Avon 525B turbojets
Thrust:
(Comet 1) 20,050 lb (89.2 kN)
(Comet 1A) 20,050 lb (89.2 kN)
(Comet 2) 29,225 lb (130 kN)
(Comet 3) 40,000 lb (178 kN)
(Comet 4) 42,000 lb (187 kN)
(Comet 4B) 42,000 lb (187 kN)
(Comet 4C) 42,000 lb (187 kN)

PERFORMANCE:
cruise speed:
(Comet 1) 450 mph (725 km/h)
(Comet 1A) 450 mph (725 km/h)
(Comet 2) 480 mph (770 km/h)
(Comet 3) 500 mph (805 km/h)
(Comet 4) 500 mph (805 km/h)
(Comet 4B) 525 mph (850 km/h)
(Comet 4C) 500 mph (805 km/h)
Initial Climb Rate: unknown
Service Ceiling:
(Comet 1) 42,000 ft (12,800 m)
(Comet 1A) 42,000 ft (12,800 m)
(Comet 2) 42,000 ft (12,800 m)
(Comet 3) 40,000 ft (12,200 m)
(Comet 4) 40,000 ft (12,200 m)
(Comet 4B) 37,700 ft (11,500 m)
(Comet 4C) 39,000 ft (11,900 m)
Range:
(Comet 1) 1,300 nm (2,415 km)
(Comet 1A) 1,535 nm (2,850 km)
(Comet 2) 2,195 nm (4,065 km)
(Comet 3) 2,345 nm (4,345 km)
(Comet 4) 2,800 nm (5,190 km)
(Comet 4B) 2,170 nm (4,025 km)
(Comet 4C) 3,725 nm (6,900 km)
g-Limits: unknown

KNOWN VARIANTS:
G-5-1 and G-5-2: Two prototypes originally equipped with single-wheel main landing gear, G-5-1 later modified with 4-wheel gear; prototypes also modifed to test drooped leading edges and rocket assisted takeoffs
Comet 1: First production model and first aircraft to initiate commercial jet passenger sevice, entire Comet fleet grounded following crash of five of these models leading to discovery of structural failure of the passenger cabin; 9 built (5 crashed)
Comet 1A: Similar to Comet 1 but with increased fuel capacity and reinforced structure for greater takeoff weight; 10 built (3 crashed)
Comet 1XB: Comet 1A aircraft modified with stronger structure and oval windows to correct problems with earlier models; 4 converted
Comet 2X: Developmental aircraft converted from a Comet 1 airframe and used to test new engines and other features for Comet 2; 1 converted
Comet 2: Enlarged model with stretched fuselage for increased passenger load and larger fuel capacity, ordered by commercial operators but never entered service because of Comet 1 crashes; 22 built but 5 scrapped, 3 put into storage, and remainder converted into following variants primarily used by the RAF
Comet C.2: Cargo transport converted from aborted Comet 2 airframes with reinforced fuselage and cabin floor, used by RAF; 8 converted
Comet T.2: Crew trainers converted from aborted Comet 2 airframes for RAF; 2 converted
Comet 2E: Comet 2 airframes modified with new engines and used to test equipment for Comet 4; 2 converted
Comet 2R: Comet 2 airframes fitted with special electronics in an unpressurized fuselage, used by the RAF; 3 converted
Comet 3: Developmental model with lengthened fuselage for more passengers and fuel but project cancelled following Comet 1 accidents, leter used as prototype for Comet 4B; 1 built and 10 others scrapped
Comet 4: First variant certified for passenger operations following Comet 1 disaster, similar to Comet 3; 28 built
Comet 4A: Short range version of Comet 4 with lengthened fuselage and reduced wingspan, order from Capital Airlines cancelled and did not enter production; none built
Comet 4B: Short range version of Comet 4 similar to Comet 4A but with even longer fuselage and new engine; 18 built
Comet 4C: Final production model, combined lengthened fuselage of Comet 4B with wing of Comet 4 for greater passenger load over standard ranges; 23 built
Comet C.4: Transport variant of Comet 4C used by RAF; 5 built
Comet 5: Proposed new model to compete with DC-8 and Boeing 707, not built
Nimrod: Maritime reconnaissance aircraft developed from basic Comet 4C airframe


KNOWN OPERATORS:
Civil:
Aerolineas Argentinas
Air France
Air India
BOAC
British Commonwealth Pacific
British European Airways
Canadian Pacific Airlines
Channel Airways
Dan-Air London
East African Airlines
Japan Air Lines
King Ibn Saud of Saudi Arabia
Kuwait Airways
LAV
Malaysia Singapore
Mexicana Airlines
Middle East Airlines
Misrair
Olympic Airways
Panair do Brasil
Royal Aircraft Establishment
Sudan Airways
Union Aeromaritime de Transport
United Arab Airlines
Government/Military:
Royal Canadian Air Force
UK Ministry of Aviation
UK Royal Air Force




Diterjemahkan secara bebas dari: www.fas.org

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