Name: 諾斯羅普-格魯曼B-2精神號 (Northrop Grumman B-2 Spirit)
Uploaded: 2021-01-14T05:24:10.000Z
Duration: 43 min 51 s
Description: 【看影片學英語】數萬部 YouTube 影片，搭配英漢字典即點即查，輕鬆掌握單字發音與用法，長久累積看電影不必再看字幕。

The Northrop B-2 Spirit, also known as the Stealth Bomber, is an American strategic bomber,

featuring low observable stealth technology designed for penetrating dense anti-aircraft

defenses; it is able to deploy both conventional and nuclear weapons. The bomber has a crew

of two and can drop up to eighty 500 lb-class JDAM GPS-guided bombs, or sixteen 2,400 lb

B83 nuclear bombs. The B-2 is the only aircraft that can carry large air-to-surface standoff

weapons in a stealth configuration. Development originally started under the "Advanced

Technology Bomber" project during the Carter administration, and its performance was one

of his reasons for the cancellation of the supersonic Rockwell B-1 Lancer. ATB continued

during the Reagan administration, but worries about delays in its introduction led to the

reinstatement of the B-1 program as well. Program costs rose throughout development.

Designed and manufactured by Northrop Grumman with assistance from Boeing, the cost of each

aircraft averaged US$737 million. Total procurement costs averaged $929 million per aircraft,

which includes spare parts, equipment, retrofitting, and software support. The total program cost

including development, engineering and testing, averaged $2.1 billion per aircraft in 1997.

Because of its considerable capital and operating costs, the project was controversial in the

U.S. Congress and among the Joint Chiefs of Staff. The winding-down of the Cold War in

the latter portion of the 1980s dramatically reduced the need for the aircraft, which was

designed with the intention of penetrating Soviet airspace and attacking high-value targets.

During the late 1980s and 1990s, Congress slashed plans to purchase 132 bombers to 21.

In 2008, a B-2 was destroyed in a crash shortly after takeoff, and the crew ejected safely.

A total of 20 B-2s remain in service with the United States Air Force, who plan to operate

the B-2 until 2058. The B-2 is capable of all-altitude attack

missions up to 50,000 feet, with a range of more than 6,000 nautical miles unrefuelled

and over 10,000 nautical miles with one refueling. Though originally designed primarily as a

nuclear bomber, it was first used in combat to drop conventional bombs on Serbia during

the Kosovo War in 1999, and saw continued use during the war in Iraq and in Afghanistan.

In the mid-1970s, the search for a new U.S. strategic bomber to replace the Boeing B-52

Stratofortress was underway, to no avail. First the B-70 and then the B-1A were canceled

after only prototypes of each aircraft were built. The B-70 was intended to fly above

and beyond defensive interceptor aircraft, only to find these same attributes made it

especially vulnerable to surface-to-air missiles. The B-1 attempted to avoid SAMs by flying

close to the ground to use terrain to mask its radar signature, only to face a new generation

of interceptors with look-down/shoot-down capabilities that could attack them from above.

By the mid-1970s, it was becoming clear that there was a different way to avoid missiles

and intercepts; known today as "stealth"; the concept was to build an aircraft with

an airframe that deflected or absorbed radar signals so that little was reflected back

to the radar unit. An aircraft having stealth characteristics would be able to fly nearly

undetected and could be attacked only by weapons and systems not relying on radar. Although

such possibilities existed, such as human observation, their relatively short detection

range allowed most aircraft to fly undetected by defenses, especially at night.

In 1974, DARPA requested information from U.S. aviation firms about the largest radar

cross-section of an aircraft that would remain effectively invisible to radars. Initially,

Northrop and McDonnell Douglas were selected for further development. Lockheed had experience

in this field due to developing the Lockheed A-12 and SR-71, which included a number of

stealthy features, notably its canted vertical stabilizers, the use of composite materials

in key locations, and the overall surface finish in radar-absorbing paint. A key improvement

was the introduction of computer models used to predict the radar reflections from flat

surfaces where collected data drove the design of a "faceted" aircraft. Development of the

first such designs started in 1975 with "the hopeless diamond", a model Lockheed built

to test the concept. Plans were well advanced by the summer of

1975, when DARPA started the Experimental Survivability Testbed project. Northrop and

Lockheed were awarded contracts in the first round of testing. Lockheed received the sole

award for the second test round in April 1976 leading to the Have Blue program.

ATB program By 1976, these programs progressed to where

a long-range strategic stealth bomber appeared viable. President Carter was aware of these

developments during 1977, and it appears to have been one of the major reasons the B-1

was canceled. Further studies were ordered in early 1978, by which point the Have Blue

platform had flown and proven the concepts. During the 1980 presidential election in 1979,

Ronald Reagan repeatedly stated that Carter was weak on defense, and used the B-1 as a

prime example. In return, on 22 August 1980, the Carter administration publicly disclosed

that the United States Department of Defense was working to develop stealth aircraft, including

The Advanced Technology Bomber began in 1979. Full development of the black project followed,

and was funded under the code name "Aurora". After the evaluations of the companies' proposals,

the ATB competition was narrowed to the Northrop/Boeing and Lockheed/Rockwell teams with each receiving

a study contract for further work. Both teams used flying wing designs. Northrop had prior

experience developing the YB-35 and YB-49 flying wing aircraft. The Northrop design

was larger while the Lockheed design included a small tail. In 1979, designer Hal Markarian

produced a sketch of the aircraft, that bore considerable similarities to the final design.

The Air Force originally planned to procure 165 of the ATB bomber.

The Northrop/Boeing team's ATB design was selected over the Lockheed/Rockwell design

on 20 October 1981. The Northrop design received the designation B-2 and the name "Spirit".

The bomber's design was changed in the mid-1980s when the mission profile was changed from

high-altitude to low-altitude, terrain-following. The redesign delayed the B-2's first flight

by two years and added about US$1 billion to the program's cost. An estimated US$23 billion

was secretly spent for research and development on the B-2 by 1989. MIT engineers and scientists

helped assess the mission effectiveness of the aircraft under a five-year classified

contract during the 1980s. Secrecy and espionage

Both during development and in service, there has been considerable importance placed to

the security of the B-2 and its technologies. Staff working on the B-2 in most, if not all,

capacities have to achieve a level of special-access clearance, and undergo extensive background

checks carried out by a special branch of the Air Force.

For the manufacturing, a former Ford automobile assembly plant in Pico Rivera, California,

was acquired and heavily rebuilt; the plant's employees were sworn to complete secrecy regarding

their work. To avoid the possibility of suspicion, components were typically purchased through

front companies, military officials would visit out of uniform, and staff members were

routinely subjected to polygraph examinations. The secrecy extended so far that access to

nearly all information on the program by both Government Accountability Office and virtually

all members of Congress itself was severely limited until mid-1980s.

In 1984, a Northrop employee, Thomas Cavanaugh was arrested for attempting to sell classified

information to the Soviet Union; the information was taken from Northrop's Pico Rivera, California

factory. Cavanaugh was eventually sentenced to life in prison and released on parole in

2001. The B-2 was first publicly displayed on 22

November 1988 at Air Force Plant 42, Palmdale, California, where it was assembled. This viewing

was heavily restricted, and guests were not allowed to see the rear of the B-2. However,

Aviation Week editors found that there were no airspace restrictions above the presentation

area and took photographs of the aircraft's then-secret planform and suppressed engine

exhausts from the air, to the USAF's disappointment. The B-2's first public flight was on 17 July

1989 from Palmdale to Edwards AFB. In October 2005, Noshir Gowadia, a design

字幕列表影片播放

諾斯羅普-格魯曼B-2精神號 (Northrop Grumman B-2 Spirit)

force

crew

spirit

development