Boeing B-47 Stratojet

Boeing B-47 Stratojet
Name	B-47 Stratojet
Caption	A Boeing B-47E Stratojet in flight.
Type	Strategic bomber
National origin	United States
Manufacturer	Boeing
Designer	George S. Schairer
First flight	17 December 1947
Introduction	June 1951
Retired	1969 (USAF), 1977 (USAF drones)
Status	Retired
Primary user	United States Air Force
Number built	2,032
Developed from	Boeing XB-47
Developed into	Boeing B-52 Stratofortress

Boeing B-47 Stratojet was a long-range, six-engined, jet-powered strategic bomber designed to fly at high subsonic speeds and at high altitudes to avoid enemy interceptor aircraft. It was a critical component of the United States Air Force's Strategic Air Command during the early years of the Cold War, serving as the nation's primary nuclear deterrent. The B-47's revolutionary design, featuring swept wings and podded engines, became the template for future large jet aircraft. Although never used in combat, its presence defined a generation of aerial warfare strategy.

Development and design

The genesis of the B-47 can be traced to a 1943 request by the United States Army Air Forces for a jet-powered reconnaissance bomber. Early designs were conventional until Boeing engineers, led by George S. Schairer, incorporated captured German research on swept wings, dramatically improving high-speed performance. The prototype, the Boeing XB-47, first flew in 1947, piloted by Robert Robbins and Scott Osler. Its radical design featured thin, 35-degree swept wings, six General Electric J47 turbojet engines mounted in pods under the wings, and a tandem cockpit for a pilot and co-pilot, with a separate compartment for a bombardier in the nose. The aircraft's landing gear was an unusual bicycle arrangement with outrigger wheels on the wings. The design process was highly competitive, with rival proposals from Convair and North American Aviation, but the Boeing design proved superior. The production decision was accelerated by the onset of the Korean War and rising tensions with the Soviet Union.

Operational history

The B-47 entered service with the Strategic Air Command in 1951, becoming the backbone of the U.S. nuclear deterrent force throughout the 1950s. Crews maintained a constant state of readiness under the Cold War doctrine of Massive retaliation, with bombers kept on alert and capable of rapid deployment from bases like SAC's March Air Force Base and Pease Air Force Base. The B-47's primary mission was to penetrate deep into the Soviet Union and deliver nuclear weapons, a role that required extensive aerial refueling from KC-97 and later Boeing KC-135 tankers. While never used in combat, the aircraft participated in numerous global training exercises and show-of-force deployments. The demanding nature of high-speed, low-altitude penetration tactics led to a significant accident rate. By the early 1960s, the B-47 was gradually phased out in favor of the more capable Boeing B-52 Stratofortress and the supersonic Convair B-58 Hustler, with the last active bombers retired by 1966. Some airframes were converted into reconnaissance or drone control aircraft, serving until 1977.

Variants

The primary production model was the B-47E, which featured more powerful J47-GE-25 engines, a reinforced structure, and an MD-7 fire control system for a remote-controlled tail turret armed with two 20 mm cannons. The RB-47B and RB-47E were dedicated photographic and electronic reconnaissance variants operated by the Strategic Air Command and used extensively for intelligence-gathering missions along the borders of the Soviet Union. The EB-47E was an electronic warfare platform. The B-47B was an interim model with less powerful engines. The final variant was the QB-47, a target drone used for testing missiles like the Boeing CIM-10 Bomarc and the IM-99 at sites such as the White Sands Missile Range.

Operators

The sole primary operator was the United States Air Force, specifically its Strategic Air Command. Numerous SAC wings operated the Stratojet, including the 306th Bombardment Wing at MacDill Air Force Base and the 380th Bombardment Wing at Plattsburgh Air Force Base. The U.S. Air Force also used the aircraft for test and development work at facilities like Edwards Air Force Base and Wright-Patterson Air Force Base. No B-47s were exported under the Military Assistance Program, though the design influenced international aircraft like the English Electric Canberra.

Specifications (B-47E)

* **Crew:** 3 (pilot, co-pilot, bombardier/navigator) * **Length:** 109 ft 10 in (33.5 m) * **Wingspan:** 116 ft 0 in (35.4 m) * **Height:** 28 ft 0 in (8.5 m) * **Empty weight:** 79,074 lb (35,867 kg) * **Max takeoff weight:** 230,000 lb (104,326 kg) * **Powerplant:** 6 × General Electric J47-GE-25 turbojet engines, 7,200 lbf (32 kN) thrust each * **Maximum speed:** 607 mph (977 km/h, 527 kn) at 16,300 ft (5,000 m) * **Range:** 3,935 mi (6,332 km) with 20,000 lb (9,100 kg) bombload * **Service ceiling:** 40,500 ft (12,300 m) * **Armament:** 2 × 20 mm (0.787 in) M24A1 cannons in a remote-controlled tail turret * **Bombs:** Up to 20,000 lb (9,100 kg) of nuclear or conventional ordnance, including the Mark 15 nuclear bomb or the B28 nuclear bomb

Aircraft on display

Several B-47s are preserved in museums across the United States. A B-47E is on display at the National Museum of the United States Air Force at Wright-Patterson Air Force Base in Ohio. The Strategic Air Command & Aerospace Museum in Ashland, Nebraska houses another example. The March Field Air Museum in Riverside, California and the Pima Air & Space Museum in Tucson, Arizona also have Stratojets in their collections. An RB-47H reconnaissance variant is displayed at the Museum of Aviation at Robins Air Force Base in Georgia.

Category:United States bomber aircraft 1940–1949 Category:Swept-wing aircraft Category:Six-engined jet aircraft Category:Cold War strategic bombers of the United States