On November 22, 1948, the Air Force issued a letter contract for an initial order of ten B-47A service test examples, and future procurement of three more B-47As was scheduled. The three additional B-47As were later cancelled. The ten B-47As were scheduled for delivery between April and November 1950.
Unlike the two prototypes, the B-47As (company designation Model 450-10-9) were all built at the government-owned but Boeing-operated factory in Wichita, Kansas. All subsequent Boeing-built Stratojets were also manufactured at Wichita. This was done because Boeing's Seattle plant was already committed to the KC-97 and B-50 projects, plus the revamping of obsolescent B-29s as mid-air refuelling tankers.
The first B-47A flew on June 25, 1950. The B-47A was essentially identical to the XB-47 prototypes, differeng externally only in having a framed Perspex nose cone in place of the fully-transparent nosecone of the prototypes. The B-47A was powered by six 5200 lb.s.t. J-47-GE-ll turbojets and retained the built-in JATO feature of the prototypes. It increased takeoff weight from 121,080 pounds to 151,324 pounds.
It took another year to deliver all ten B-47As on the order. Throughout 1950-51, flight testing of the B-47A and the first XB-47 continued. Unfortunately, neither plane was very safe to operate. Both the XB-47 and the B-47A were seriously underpowered, and critical braking problems occurred during aborted takeoffs and after gross weight landings on wet runways.
In order to reduce the length of the landing run, a 32-foot deceleration parachute was provided that was stowed underneath the tail just forward of the tail cone. Conventional solid parachutes could not stand the aerodynamic load imposed by such high speeds without ripping, so a special ribbon type of parachute originally developed in Germany was designed. This chute was deployed immediately after touchdown to help slow down the aircraft and shorten the landing roll. However, it soon became customary practice to deploy the drag chute while the B-47 was still a few feet in the air just before touchdown.
Since the poor acceleration characteristics of the jet engines of those times (it could take as long as 20 seconds to spool the engines up from idle) made go-arounds after an aborted landing hazardous, a second and smaller sixteen-foot drogue or deceleration parachute was developed that acted as an inflight air brake that made it possible to make landing approaches at relatively high engine powers. If a go-around became necessary, the drogue chute could be immediately jettisoned and the airplane could accelerate quickly. If the landing was normal, the drogue chute could be left attached while the main braking chute was deployed.
Following the end of the landing roll, both the landing and braking chutes were jettisoned at the end of the runway before the B-47 taxiied in. The chutes were recovered and repacked by the ground crews.
There were several problems with the ejection seat equipment of the B-47A. In fact, things got so bad that the ejector seats were actually removed after an XB-47 accident in which the pilot was killed. As a substitute, an additional escape hatch and bail-out spoiler were provided underneath the nose.
Deliveries of the B-47A to the USAF began in December of 1950. The B-47A entered service in May of 1951 with the 306th Bombardment Wing, Medium, based at MacDill AFB in Florida. The 306th was intended to act as a training outfit to prepare future B-47 crews. The B-47As were primarily training aircraft and were not considered as being combat ready, since most of them were unarmed and were initially without almost any of their vital electronic components. Only four of the ten had the K-2 bombing navigation system. The tail armament of two 0.50-inch machine guns was tested with an A-2 fire control system on 49-1906 and with an A-5 fire control system on 49-1908. None of the B-47As ever saw any operational duty, but some of them stayed with the Air Proving Command.
Serials of B-47A:
49-1900/1909 Boeing B-47A Stratojet Model 450-10-9 c/n 450001/450010
Specification of Boeing B-47A Stratojet:
Engines: Six General Electric J47-GE-11 turbojets, rated at 5200 lb.s.t. each. Performance: Maximum speed 600 mph at 8800 feet. Service ceiling 38,000 feet. Combat ceiling 44,300 feet. Initial climb rate 3375 feet per minute. Combat radius 1550 miles. Range 2650 miles with 10,000 pound bombload. Ferry range 4000 miles. Takeoff ground run 6000 feet at sea level. Dimensions: Wingspan 116 feet 0 inches, length 106 feet 9 inches, height 27 feet 8 inches, wing area 1428 square feet. Weights: 73,240 pounds empty, 106,060 pounds normal loaded, 157,000 pounds maximum takeoff. Armament: Two 0.50-inch machine guns in tail turret (not actually fitted). Normal bombload 10,000 pounds. Up to 16 1000-pound bombs or one 22,000 pound bomb could be carried.
Sources:
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American Combat Planes, Third Enlarged Edition, Ray Wagner, Doubleday,
1982.
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Post World War II Bombers, Marcelle Size Knaack, Office of Air Force
History, 1988.
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The Boeing B-47, Peter Bowers, Aircraft in Profile, Doubleday, 1968.
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Boeing Aircraft Since 1916, Peter M. Bowers, Naval Institute Press,
1989.
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United States Military Aircraft Since 1909, Gordon Swanborough and
Peter M. Bowers, Smithsonian, 1989.
- Boeing B-47 Stratojet--Variant Briefing. Bill Yenne, International Air Power Review, Vol 6, 2002.
