Most Stealth Bomber In the World

After WW2, there was United States of America and the Soviet Union involved in the cold war. Both countries wanted to become the most powerful country in the world. Therefore, both countries wanted to innovate new things to defeat each other. As a result of the cold war, most fields like engineering, space, and science were developed very fast. The military is the key point of global power. So, they invested their money in inventing new technologies on air crafts, missiles, warships, and much more military equipment.

Radar technology was invented in the WW2 period. So, the air crafts should hide from enemy radars and complete the targets. In the mid-time periods of the 1970s, military air crafts designers researched new technology to avoid radars. Nowadays it introduces as "stealth". The concept was to build aircraft with airframes that can absorb radar signals or deflect radar signals. As a result of this, little amount of radar signals is reflected back to the radar. Radar is not the only threat to the aircraft. Military air crafts should be careful of human observation, infrared scanners, and acoustic positioning. So, the US air force wanted an aircraft with full stealth and avoid these threats.

In 1974, DARPA(Defence Advanced Research Projects Agency) requested information about stealth aircraft from US aviation firms. After, Northrop and McDonnell Douglas were selected for the latest stealth aircraft's further developments. And also Lockheed Martin had a good experience in this field because it designed and invented the Lockheed A-12 and SR-71.

Lockheed A-12

The developments were rapidly developed by the summer of 1975 when DARPA started its Experimental Survivability Testbed (CST) project. Northrop and Lockheed Martin were awarded contracts in the first round of testing of the stealth aircraft. So, Lockheed Martin passed the first testing and qualified for the 2nd test in 1976 and which leads Lockheed martin to the Have Blue program and eventually the F-117 stealth attack aircraft. Northrop also had a classified technology demonstration aircraft, the Tacit Blue in development in 1979 at Area 51. It developed stealth technology, curved surfaces, composite materials, electronic intelligence (ELINT), and Battlefield Surveillance Aircraft Experimental (BSAX).

 B-2's first public flight was in 1989

With these technologies, the B-2 spirit was invented by Northrop Grumman as an advanced technology bomber in 1989 with a US$23 billion estimation. But the program cost was increased to US$ 44.75 billion in 2004. From then, until today, Northrop Grumman B-2 Spirit is the main stealth bomber in the world's largest air force which is the US air force. In 1997, the unit cost of  B-2 spirit is US$ 737 million. Now, it costs US$2.1 billion each. It can be introduced as the highest expensive aircraft in the world. Because of this high cost, only 21 units are developed until now. 

Northrop Grumman B-2 Spirit

The key characteristics of B-2 Spirit are shown below:

• Maximum speed: 1,010km/h (Mach 0.95)
• Weight : 71,700kg (without payload)
• Max takeoff weight: 170,600kg 
• Wingspan: 52.4m
• Fuel capacity : 75,750kg
• crew: 2 pilots (pilot and mission commander)
•  
• Range: 11,000 km

It costs approximately $130,000 per flight hour.

B-2 Spirit takeoff 

Two internal bays for ordnance and payload with an official limit of 40,000 lb (18,000 kg); the maximum estimated limit is 50,000 lb (23,000 kg)

• 80× 500 lb (230 kg) class bombs (Mk-82, GBU-38) 
• 36× 750 lb (340 kg) CBU class bombs
• 16× 2,000 lb (910 kg) class bombs (Mk-84, GBU-31)
• 16× B61 or B83 nuclear bombs
• Standoff weapon: AGM-154 Joint Standoff Weapon (JSOW) and AGM-158 Joint Air-to-Surface Standoff Missile (JASSM)
• 2× GBU-57 Massive Ordnance Penetrator

B-2 Spirit with weapons

Northrop Grumman B-2 Spirit actively participated in US air force operations 

• The B-2 saw service in Afghanistan, striking ground targets in support of Operation Enduring Freedom. With aerial refueling support, the B-2 flew one of its longest missions to date from Whiteman Air Force Base in Missouri to Afghanistan and back. B-2s would be stationed in the Middle East as a part of a US military buildup in the region from 2003.
• In March 2011, B-2s were the first U.S. aircraft into action in Operation Odyssey Dawn, the UN-mandated enforcement of the Libyan no-fly zone. Three B-2s dropped 40 bombs on a Libyan airfield in support of the UN no-fly zone. The B-2s flew directly from the U.S. mainland across the Atlantic Ocean to Libya; a B-2 was refueled by allied tanker aircraft four times during each round trip mission.
• On 28 March 2013, two B-2s flew a round trip of 13,000 miles (21,000 km) from Whiteman Air Force base in Missouri to South Korea, dropping dummy ordnance on the Jik Do target range. The mission, part of the annual South Korean–United States military exercises, was the first time that B-2s overflew the Korean peninsula. Tensions between the Koreas were high; North Korea protested against the B-2's participation and made threats of retaliatory nuclear strikes against South Korea and the United States
• On 18 January 2017, two B-2s attacked an ISIS training camp 19 miles (30 km) southwest of Sirte, Libya, killing around 85 militants. The B-2s together dropped 108 500-pound (230 kg) precision-guided Joint Direct Attack Munition (JDAM) bombs. These strikes were followed by an MQ-9 Reaper unmanned aerial vehicle firing Hellfire missiles. Each B-2 flew a 33-hour, round-trip mission from Whiteman Air Force Base, Missouri with four or five (accounts differ) refuelings during the trip.