Northrop YB-49

History of the Northrop YB-49

The YB-49 strategic bomber prototype was an extension of the eventually abandoned XB-35/YB-35 program. The main difference between the two lines is the YB-49's move to pure turbojet engines (the B-35 series relies on radial piston engines in a "push-rod" configuration).

Like the XB-35/YB-35 that preceded it, the YB-49 was eventually cancelled. Only two have been completed, with seven remaining in various stages of conversion from the YB-35 standard.

The pre-production quality YB-35 was the basis for two YB-49 prototypes and was part of the USAF's conversion to jet-powered form at the end of World War II (1939-1945). The installation of eight Allison J35 turbojets (4,000 pounds of thrust each) immediately improved performanceespecially at top speed and altitude, while reducing range by 50 percent compared to piston-powered versions.

The general arrow design was retained, and the crew of nine was now reduced to seven.

The YB-49 prototype flew for the first time on October 21, 1947, and showed great promise in testing. All gains were lost when the second fuselage crashed on June 5, 1948, killing all of its crewthe main-wing plane was partially detached from the fuselage in flight and could not be salvaged. In February 1949, a YB-49 completed a flight from Muroc AFB to Andrews AFB in 4 hours and 25 minutes.

On the return trip, half of the engines had problems and were shut down.

With the termination of the YB-35 program in 1949, the YB-49 continued. Yet another crash in March 1950 only added to the project's problems. A collapsed nose wheel was blamed for the accident, with fire spreading from the fully fueled plane. At this time, the YB-35 production line has been converted to the turbojet form.

Overall, the YB-49 performed well despite its well-publicized problems.

Like the YB-35, the YB-49 faced technical challenges and political issues at both the industry and government levels. Northrop Aerospace founder Jack Northrop didn't realize his dream of becoming a flying wing until shortly before his death in 1981, when he first saw the B-2 "Spirit" stealth bomber in development.

Spirit officially entered service in 1997 and is still flying today (2015).

When completed, the YB-49 has a crew of 7 and dimensions include a barrel length of 16 meters, a wingspan of 52.4 meters and a height of 6.2 meters. The kerb weight is 40,115kg and the maximum take-off weight (MTOW) is 88,000kg. Power comes from eight Allison/General Electric J35-A-5 series turbojet engines, each producing 4,000 pounds of thrust.

Performance includes a top speed of 495 mph, a range of up to 9,980 miles (ferry), a combat radius of 1,615 miles, a service ceiling of 45,700 feet and a rate of climb approaching 3,760 feet per minute. The proposed weapon is a 4 x .50 caliber Browning M3 Heavy Machine Gun (HMG) in a rear "stinger" position (as shown in the proposed XB-35/YB-35).

The internal bomb load was 32,000 pounds, well below the B-35 design's estimated wartime load of 51,000 pounds.

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