Pembangunan dan kegunaan Perisai Chobham

Sejak awal 1960-an, A.S membuat banyak penyelidikan ekstensif bagi mencari prospek untuk menggunakan bahan-bahan seramik komposit sebagai perisai kenderaan.[14]. Penyelidikan ini tertumpu akan penggunaan logam matriks aluminum yang diperkuat dengan juraian silikon karbida, yang akan dikeluarkan dalam bentuk helaian besar.[15] Helaian logam ringan yang diperkuat ini kemudian diapitkan di antara lapisan keluli.[16] Aturan ini memiliki kebaikan dan berupaya untuk menerima tembakan berulang dan boleh dibentuk. Ini membolehkan perisai utama dibentuk berdasarkan bentuk perisai bercerun. Bagaimanapun, tujuan utama perisai komposit dengan kandungan logam yang tinggi ini adalah untuk meningkatkan perlindungan untuk bertahan dari tembakan peluru penembus tenaga kinetik berdasarkan berat perisai yang diberi; prestasi perisai ini dalam bertahan terhadap tembakan peluru letupan berbentuk adalah tidak berapa baik dan perlu diperbaiki.

Teknologi pilihan yang dibangunkan di A.S berdasarkan penggunaan modul kaca yang akan dimasukkan ke dalam perisai utama;[17] meskipun susunan ini menawarkan peningkatan ke atas pelindungan dari peluru letupan berbentuk, keupayaannya untuk menerimaa tembakan berulang sangat rendah. Sistem sama yang menggunakan kaca yang dimasukkan ke dalam perisai utama keluli berdasarkan teknologi 1950-an untuk prototaip kereta kebal Soviet Obiekt 430 bagi program kereta kebal T-64;[18] this was later developed into the "Combination-K" type, having a ceramic compound mixed with the silicon oxide inserts, which offered about 50% better protection against both shaped charge and KE-penetrator threats, compared with a steel armour of the same weight.[19] It was, later in improved forms, part of all subsequent Soviet main battle tank designs. After an initial period of speculation in the West as to its true nature, the characteristics of this type were disclosed when the dissolution of the Soviet Union and the introduction of a market system forced the Russian industries to find new customers by highlighting its good qualities;[20] it is today rarely referred to as Chobham armour.

Meanwhile in the United Kingdom another line of ceramic armour development had been started, meant to improve the existing cast turret configuration of the Chieftain that already offered excellent heavy penetrator protection; the research by a team headed by Gilbert Harvey of the Fighting Vehicles Research and Development Establishment, was thus strongly oriented at optimising the ceramic composite system for defeating shaped charge attack[21]. The British system consisted of a honeycomb matrix with ceramic tiles backed by ballistic nylon[22], placed on top of the cast main armour.[17] In July 1973 an American delegation, in search of a new armour type for the XM815 tank prototype, now that the MBT-70 project had failed, visited Chobham Common to be informed about the British system. It was very impressed by the excellent shaped charge protection combined with the penetrator impact damage limitation, inherent to the principle of using tiles. The Ballistic Research Laboratory at the Aberdeen Proving Ground that year initiated the development of a version, named Burlington, adapted to the specific American situation with a much higher projected tank production run and the use of a thinner rolled steel main armour. The increased threat posed by a new generation of Soviet guided missiles armed with a shaped charge warhead — as exemplified by the events of the Yom Kippur War of October 1973, when even older generation missiles caused considerable tank losses on the Israeli side — made Burlington the preferred choice for the armour configuration of the XM1 (the renamed XM815) prototype.[23]

However, on 11 December 1974 a Memorandum of Understanding was signed between the Federal Republic of Germany and the USA about the common future production of a main battle tank; this made any application of Chobham armour dependent on the eventual choice for a tank type. Earlier in 1974 the Americans had asked the Germans to redesign the existing Leopard 2 prototypes, considered by them too lightly armoured and had suggested to adopt Burlington for this purpose; the Germans however in response that year initiated a new armour development programme of their own.[24] Having already designed a system that in their opinion offered satisfactory protection against shaped charges, consisting of multiple laminate spaced armour with the spaces filled with ceramic polystyrene foam[25] as fitted to the Leopard 1A3, they put a clear emphasis on improving KE-penetrator protection reworking the system into a perforated metal module armour. A version with added Burlington was considered, including ceramic inserts in the various spaces, but rejected as it would push vehicle weight well over sixty metric tonnes, a weight then seen as prohibitive by both armies[26]. The US Army in the summer of 1974 faced the choice between the German system and their own Burlington, a decision made more difficult by the fact that Burlington offered, compared with steel armour, no weight advantage against KE-penetrators:[27] the total armour system would have a RHA equivalence against them of about 350 mm (compared to about 700 mm against shaped charges).[28] No consensus developing, General Creighton Abrams himself decided the issue in favour of Burlington.[29] Eventually each army would procure its separate national tank design, the project of a common tank failing in 1976. In February 1978 the first tanks protected by Burlington left the factory when the first of eleven pilot M1 tanks were delivered to the US Army.

Di United Kingdom, penggunakan perisai Chobham agak terlambat disebabkan kegagalan beberapa projek kereta kebal termmaju: pertama usahasama kereta kebal Jerman-Britain; kemudian program MBT-80 Britain. Kerajaan Iran telah memesan sejumlah 1,225 buah kereta kebal Chieftain yang ditingkat upaya, dan dinamakan sebagai Shir-2 (FV 4030/3), dengan memasang perisai Chobham pada perisai utama kereta kebal, menjadikan berat keseluruhannya meningkat kepada 62 tan metrik. Apabiba pesanan ini dibatalkan pada Februari 1979 setelah berlakunya Revolusi Iran, kerajaan Britain dengan tekanan bagi memodenkan angkatan kereta kebal mereka agar lebih hebat secara relatif berbanding angkatan kereta kebal Kesatuan Soviet, telah memutuskan untuk menggunakan keupayaan lebihan pengeluaran bagi membeli sejumlah kenderaan yang hampir menyamai rekabentuk kereta kebal Shir-2, yang dikenali sebagai Challenger 1. Pada 12 April 1983, kereta kebal pertama Britain yang dilindungi dengan perisai Chobham telah diserahkan kepada Royal Hussars.

Versi terkini perisai Chobham telah digunakan pada kereta kebal Challenger 2 (dikenali sebagai "perisai Dorchester"), dan (komposisi bahan mungkin berbeza) kereta kebal siri M1 Abrams, yang mana berdasarkan sumber-sumber rasmi menyatakan bahawa kereta kebal ini kini dilindungi dengan kepingan silikon karbida. Given the publicly stated protection level for the earliest M1: 350 mm steel equivalence against KE-penetrators (APFSDS), ia seolah-olah dilengkapi dengan kepingan alumina.[penyelidikan asli?]

Walaupun didakwa sebaliknya, dari segi fakta kereta kebal Leopard 2 tidak menggunakan perisai Chobham, tetapi perisai berlubang asli, untuk mengelakkan membuat pembelian, penyelenggaraan dan kos pengantikan tinggi ke atas sistem perisai seramik yang berasaskan alumina yang tidak berkesan. Bagi kebanyakan kereta kebal moden, seperti kereta kebal Type 90 Jepun dan Ariete Itali, jenis perisai yang akan digunakan belum diputuskan. Terdapat aliran umum yang beralih dari penggunaan perisai seramik kepada perisai berlubang.