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22-05-2008, 02:41
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חבר מתאריך: 23.09.03
הודעות: 12,141
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הנושאות החדשות (Queen Elizabeth Class) אומנם יותר גדולות, אבל מיועדות להפעיל בשלב זה את ה F-35, כך שאין צורך בקונפיגורציית ה CATOBAR. יש מאמר בוויקיפדיה שמדבר בדיוק על הדילמה הזאת. הנה קטע ממנו (הדגשתי את משפטי המפתח, שמבטאים בדיוק את נושא הדיון):
ציטוט:
Requirement
The 22,000 tonne Invincible class aircraft carriers, Invincible, Illustrious and Ark Royal, were designed for Cold War anti-submarine warfare in the North Atlantic as part of a combined NATO fleet and have limited space for offensive aircraft (nine Harrier GR7s or Sea Harriers).
In 1982 Invincible joined the task force dispatched to recover the Falkland Islands (together with the older and larger HMS Hermes). This conflict demonstrated the need to maintain aircraft carriers to support the United Kingdom's foreign policy. Since the end of the Cold War the Invincible class ships have operated in a more traditional aircraft carrier mission, that of power projection. As a result the Royal Air Force's Harrier GR7 have been routinely deployed on them and the ships have been modified to carry more aircraft and ammunition (notably with the removal of the Sea Dart defensive weapon system).
However, the capability of the Invincible class has been limited by the size of the vessels. The lack of dedicated Airborne Early Warning (AEW) aircraft such as the E-2C Hawkeye was a significant liability during the Falklands War. As the Invincible class could not deploy such aircraft, the Royal Navy deployed inadequate solutions such as the Sea King AEW.2, which suffered from the range and sensor payload capabilities of helicopters versus fixed-wing aircraft. Despite this, formal studies did not begin until 1994 regarding the replacement of the ships, when it became more clear that larger carriers with larger air groups are necessary.
Strategic Defence Review
In May 1997, a newly-elected Labour government launched the Strategic Defence Review (SDR). This review re-evaluated every weapon system (active or in procurement) with the exception of the Eurofighter Typhoon and the Vanguard class ballistic missile submarines. The report in December 1998 concluded that aircraft carriers offered the following:
* Ability to operate offensive aircraft abroad when foreign basing may be denied.
* All required space and infrastructure; where foreign bases are available they are not always available early in a conflict and infrastructure is often lacking.
* A coercive and deterrent effect when deployed to a trouble spot.
The report concluded:
The emphasis is now on increased offensive air power, and an ability to operate the largest possible range of aircraft in the widest possible range of roles. When the current carrier force reaches the end of its planned life, we plan to replace it with two larger vessels. Work will now begin to refine our requirements but present thinking suggests that they might be of the order of 30,000–40,000 tonnes and capable of deploying up to 50 aircraft, including helicopters.
While it has been suggested that reducing the carrier force by one vessel will lead to a reduction in the ability of the Royal Navy to project carrier air power, it is planned that advanced design and maintenance techniques will eliminate the present requirement for major refits. In addition, HMS Ocean, a specialised helicopter landing platform, fills a role previously undertaken by the Invincible class carriers.
Design studies
On 25 January 1999 six companies were invited to tender for the assessment phase of the project; Boeing, British Aerospace, Lockheed Martin, Marconi Electronic Systems, Raytheon and Thomson-CSF.[5] On 23 November 1999 the MoD awarded detailed assessment studies to two consortia, one led by BAe (renamed BAE Systems on 30 November) and one led by Thomson-CSF (renamed Thales Group in 2000). The brief required up to six designs from each consortium with airgroups of 30 to 40 Future Joint Combat Aircraft (FJCA). The contracts were split into phases; The first GB£5.9 million phase was for design assessment which would form part of the aircraft selection, the second GB£23.5 million phase involved "risk reduction on the preferred carrier design option."[6]
Possible configurations of the vessels were varied:
* STOVL - F-35B Lightning II
Short Take-Off/Vertical Landing (STOVL), the current choice for UK carrier air power. A STOVL CVF would remove the need for costly steam catapults and arrestor gear (CATOBAR), and would also take advantage of the UK lead in STOVL technology. This is at the expense of aircraft range and payload capability (for an equal size CATOBAR carrier). However the difference in capability between an F-35B and F-35C is slight compared to the gulf in capability between the Harrier and, for example, the F/A-18. As RN and RAF Harrier forces have been merged it will have to be defined in the future how this F-35 will be managed. More important is that currently there are no STOVL aircraft for AWACS role or ASW. One option is using an AWACS version of V-22 Osprey, to be developed from scratch.
* STOBAR - Eurofighter Typhoon (Navalised)
Short Take-Off But Arrested Recovery (STOBAR) again removes the requirement for the expense of catapults but uses arrestor gear. In this way conventional aircraft (with modification) can be used. Any STOBAR design would most likely have used a navalised version of the Eurofighter Typhoon; i.e. strengthened landing gear, improved flight control system and inclusion of an arrestor hook suitable for carrier use. The advantages of this would be increased range, manoeuvrability and payload compared to a STOVL design and higher operating efficiency than a CATOBAR design. Disadvantages include lower stealth characteristics than the F-35, as well as the very high cost of navalising the Typhoon (with little or no export potential). The option of buying the French Rafale-M and adapting to this solution was not analysed, even when France showed interest in the project.
* CATOBAR - F-35C Lightning II - F/A-18E/F Super Hornet - Rafale M
A Catapult Assisted Take-Off But Arrested Recovery CVF would have used catapults and arrestor cables and an angled flight deck with existing naval aircraft, most likely the F/A-18 or Rafale-M. This has the advantage of reducing technical risk for development of both the aircraft and carriers and offering maximum payload and range capabilities. There are disadvantages however, including higher operating costs and the minimal British involvement in development of the aircraft due to the "off-the-shelf" purchase.
* "Hybrid"
A late BAE submission was a hybrid carrier, featuring a STOVL ski-jump with angled flight deck, catapults and arrestor cables. Advantages of this design include the ability to operate STOVL offensive aircraft and CATOBAR AEW aircraft (e.g. E-2 Hawkeye).
[edit] Aircraft and carrier format selection
On 17 January 2001 the UK signed a Memorandum of Understanding (MoU) with the U.S. Department of Defense (DoD) for full participation in the Joint Strike Fighter Programme, confirming the JSF as the FJCA. This gave the UK significant input into aircraft design and the choice between the Lockheed X-35 and Boeing X-32. On 26 October 2001 the DoD announced that Lockheed Martin had won the JSF contract.
On 30 September 2002 the MoD announced that the Royal Navy and RAF will operate the STOVL F-35B variant. At the same time it was announced that the carriers would take the form of large, conventional carriers, which will be adapted for STOVL operations. The carriers, expected to remain in service for 50 years, will be convertible to CATOBAR operations for the generation of aircraft after the F-35.
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עוד בימי מלחמת פולקלנד הבריטים הרגישו בחוסר בפלטפורמת AEW בעלת טווח\כושר נשיאה מספקים לצורך לחימה שוטפת בקנ"מ גדול, ועדיין לא מצאו פיתרון לכך.
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Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning. -Rick Cook
נערך לאחרונה ע"י DeepSpace בתאריך 22-05-2008 בשעה 02:44.
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