Boeing B-47E STRATO-JET

B-47E

The designations B-47C and B-47D were applied to special variants that never went into production (described later), and so the next production version of the B-47 was the definitive B-47E.

The first B-47E flew on 30 January 1953. Four "blocks" or "phases" of the B-47E were built, each incorporating refinements on the previous block, and also sometimes featuring production changes within a block. Older blocks were generally brought up to the specifications of later blocks as they were introduced. The B-47 also incorporated the production model with the radar controlled rear tail turret.

Early production "B-47E-Is" also known featured J47-GE-25 turbojets with 5,970 lbf (26.6 kN) thrust, but they were quickly changed to J47-GE-25A engines, which featured a significant improvement in the form of water-methanol injection. This was a scheme in which a water-methanol mix was dumped into the engines at takeoff, increasingmass flow and so temporarily kicking the thrust up to 7,200 lbf (32 kN). Methanol was apparently added to the water as an anti-freezing agent. The engines left a trail of black smoke behind them when water-methanol injection was on.

Jet-Assisted Take Off or JATO modifications were performed on early B-47E-Is. They had the 18 built-in JATO bottles, and were quickly exchanged for an external, jettisonable "split V" or "horse collar" rack fitted under the rear fuselage. The rack carried 33 JATO bottles, in three rows of 11 bottles. The built-in JATO system was eliminated because of worries about having the JATO bottles so close to full fuel tanks, and in any case once the rocket bottles were exhausted they were just dead weight. The racks were expendable, and were dropped over specific range areas after takeoff.

One welcome change in the B-47E relative to the B-47B was the return of the ejection seats, the Air Force senior leadership having reconsidered the earlier decision to delete them. In addition, the twin .50 in guns (12.7 mm) in the tail turret were replaced with twin 20 mm (0.79 in) cannon to provide more firepower, backed up by an A-5 FCS in early production and an MD-4 FCS in later production.[32]

A final change in the B-47E was that most of the windows in the nose were deleted, with only one left on each side. However, many pictures of B-47Es show them with the full set of windows used on the B-47B. Whether the number of windows varied through B-47E production, or whether these were B-47Bs updated to B-47E specification, is unclear.

The B-47E-II featured only minor changes from late production B-47E-Is. The B-47E-III featured an ECM suite, consisting of a radar jammer in a bulge under the fuselage plus a chaff dispenser, as well as improved electrical alternators.

The B-47E-IV was a much more substantial update, featuring stronger landing gear, airframe reinforcement, greater fuel capacity, and a bombload uprated to 25,000 lb (11,300 kg), though the bomb bay was once again shortened because of the introduction of more compact nuclear weapons.

Another improvement was the introduction of the MA-7A BNS, a major step up from its predecessors. The MA-7A included the AN/APS-64 radar, with a range as long as 240 mi (390 km). The AN/APS-64 could be used as a long range "identification friend or foe (IFF) transponder" interrogator to allow a B-47E-IV to find a tanker or other B-47, or it could be used as a high-resolution ground-targeting radar. The B-47E-IV retained the optical bombsight, though this was rarely used.

A total of 1,341 B-47Es were produced. A total of 691 were built by Boeing, 386 were built by Lockheed, and 264 were built by Douglas. Most B-47Bs were rebuilt up to B-47E standards. They were given the designation of B-47B-II, though it appears that in practice they were simply called B-47Es.

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Boeing B-47E STRATO-JET - 301st Bombardment Wing, Strategic Air Command, U.S.A.F., Westover Air Force Base, Mass, USA, 1962.
Boeing B-47E STRATO-JET - 380th Bombardment Wing, S.A.C., U.S.A.F., Plattsburgh Air Force Base, USA, 1964.