Aircraft

B-2 Spirit

This is my B-2 site. You will find information and facts about the B-2 Spirit.

Hover over the links below for a description of that page.

Check out http://www.airliners.net/ for about 50 pictures of the B-2 Spirit.

Background

The B-2 bomber (also known as the stealth bomber) was an extremely ambitious project. Tensions were mounting between the Soviet Union and the United States in the 1970's. The US needed a replacement for the aging B-52 bomber that could carry a nuclear weapon across the globe in only a few hours, and along the way be nearly undetectable to enemy sensors. The B-2 Spirit bomber answered that need.

The father to the B-2 was the YB-49. Lead designer, Jack Northrop, founder of Northrop Aircraft Co. (today knows as Northrop Grumman) designed several flying-wing prototypes. The company was later contracted by the US Army to build a longer-range bomber during World War II. The YB-49 was the product of years of development. Its predecessors included the Northrop Model 1 (N-1M) in 1939. It was a twin-engine flying model. Improvements led to the propeller-driven XB-35 and the YB-35. The XB-35 took its first test flight in 1946. Jet propulsion was finally added to the YB-35 model creating the YB-49. In 1947, the YB-49 took its first flight over California.

The YB-49 project was later cancelled in 1948 following an accident that killed two test pilots. The YB-49 was ahead of its day, proving difficult to fly without the aid of computers. With WWII over, the military suspended the flying-wing design. The program was resurrected with the development of the B-2.

Development of the B-2 began in 1981. Northrop Grumman (the same company that developed the YB-49) won the bid to develop the stealth bomber. In 10 years of development and costing billions of dollars to build the B-2 Spirit was born. It rolled out of the Northrop facility in Palmeda, California. It first flew on July 17, 1989, landing at Edwards Air Force Base.

Flying Wing

The difference between the flying wing design and a normal aircraft is the absence of the separate wings. Instead of the fuselage (main section of the plane, where passengers and cargo are located), two wings, and a separate tail, the entire craft is one huge wing. This design is more efficient than that of traditional planes, because the entire craft is used to generate lift. The fuselage is no longer "dead weight." Eliminating the tail also reduces drag. Reducing drag and thus increasing efficiency helps the plane to travel longer distances in a shorter amount of time. It is not the fastest aircraft, (high subsonic meaning that its top speed is just under the speed of sound), but it can go 6,900 miles (farther than Nome, Alaska, USA to Panama City, Panama) without refueling. It can go 11,500 miles with one in-flight refueling. The B-2 can fly anywhere on Earth within short notice.

The B-2 uses elevons and rudders to move the plane just like a conventional aircraft. These control surfaces change the planes direction and movement. The flying wings of the past suffered from stability problems. Without the rear stabilizers the plane suddenly tends to rotate around its yaw axis. That is the main reason the military dropped the YB-49 project. Advancements in computer technology in the 1980s however made the flying wing design a possibility. The B-2 is built with a fly-by-wire system, meaning that the control surfaces on the plane are not directly connected through mechanical means. When the pilot inputs commands through the B-2s flight stick it goes to a computer, the computer then controls the B-2.

The computer also does a lot of work automatically, independent of the pilot's input. It constantly monitors gyroscopic sensors to keep track of the planes attitude and direction. If the plane starts to turn unexpectedly, the computer automatically controls the plane to counteract the turning. These corrections are so precise that the pilot does not even know it is happening. The B-2 also has another control surface, not found on tradition aircraft. The Gust Load Alleviation System (GLAS) is a wedge-shaped flap in the middle of the trailing edge that counteracts air turbulence.

The B-2 Bomber uses a two-person crew, a pilot and a mission commander. By contrast, the B-52 requires a five-person crew.

Stealth Technology

The concept of the B-2 is stealth. The plane should be able to fly through enemy airspace undetected, destroy its target, and return home without ever engaging enemy forces. Stealth refers to near invisibility in a number of different ways. It needs to be quiet, visually disappear, conceal its electromagnetic energy, and hide from radar and infrared sensors. The planes narrow, flat shape allows, a black color allow the plane to disappear in the night. Exhaust is at a minimal so it does not leave a visible trail behind it. Unlike a passenger plane, the B-2s engines are buried within the aircraft, which helps muffle the noise and allow the planes exhaust to cool down. Infrared sensors, like those on heat-seeking missiles, detect a planes hot engine exhaust. In the B-2, all exhaust gasses pass through cooling vents reduces the planes heat signature. The exhaust ports are put on top of the plane as well, since enemy sensors will more likely scan the plane from ground.

The B-2 uses two major techniques to avoid radar. The first is the planes use of radar-absorbent surfaces. Radar works by emitting electromagnetic energy, this energy hits an object and then bounces back. The B-2s composite surfaces (combinations of lightweight material) are designed to absorb these radio waves. The B-2s leading edges (front surfaces hitting the wind first) contain expensive radio-absorbent paint and tape that has to be reapplied often. After every flight, the ground crew spends many hours inspecting the plane and repairing any damage to maintain maximum stealth.

The planes shape is the second technique to avoid enemy radar. The radio waves that are not absorbed bounce off the plane in a different direction from the source. Thus, the energy waves are not bounced back to the enemy's radar system. The concept works like a mirror. Looking straight into the mirror your image is reflected back to you. However, tilt the mirror enough and you will not be able to see your reflection because it will be reflected away from you. Bombs and landing gear fold into the planes body to eliminate more reflection. The B-2 is also designed to contain its own radio waves generated by the onboard electronics. These stealthy qualities make the 172-foot wide plane look like an insect on enemy radar.

Weapons

The original purpose of the B-2 bomber was to carry nuclear weapons to the Soviet Union. With the Soviet Union's collapse in 1991, the military redefined the B-2 Spirit's role into that of a multi-role bomber, carrying conventional weapons as well as nuclear bombs.

The B-2 is fitted with two rotary launchers that rotate the correct bomb into position when the mission commander tells the computer to do so. The bay doors open and the bomb is released. The bomb carries smart bombs (bombs that can actually seek out a target) as well as dumb bombs (bombs that just simply fall from the plane). 40,000 pounds of munitions can be carried by the B-2. The JDAMs or Joint Direct Attack Munition is actually a dumb bomb made into a precision guided smart bomb. The dumb bomb is outfitted with a "kit" that includes a GPS receiver, and inertial guidance system, maneuverable tail fins, and an internal computer. The crew uses the B-2s own GPS system to input the coordinates into the bomb. After being released, the bomb receives signals from the GPS satellites and finds its target controlling itself using its maneuverable tail fins. This system works extremely well, even in bad weather because the bomb does not need to see anything on the ground. It allows the B-2 Spirit to drop its bomb and then leave the hostile territory.