Boeing B-47 Stratojet

WB-47B

In 1956, a single B-47B was converted into a WB-47B weather reconnaissance aircraft and operated by the Military
Air Transportation Service (MATS), making it one of the few B-47s that wasn't operated by SAC.

This aircraft remained in service until the mid-1960s.

KB-47B

In 1953, two B-47Bs were modified for testing the probe-and-drogue refueling system.

The tanker was given the designation KB-47G and was known as "Maw" by flightcrews, and was fitted with a British-built
tanker kit.

The refueling test aircraft was given the designation YB-47F and was known as "Paw", though other aircraft were also used as refueling targets.

The program was cancelled in 1954 as it turned out the KB-47G simply could not carry enough fuel to make it a useful
tanker.

The idea of fielding B-47 tanker conversions came up again a few years later, but the economics didn't make sense, and the notion was finally put to rest for good in 1957.

Canadair CL-52

One of the most unusual B-47B conversions was the Canadair CL-52 which was a B-47B loaned in 1956 to the [Vous devez être inscrit et connecté pour voir ce lien] to test the new, powerful [Vous devez être inscrit et connecté pour voir ce lien] turbojet (rated at 19,250 lbf (85.6 kN) dry, 25,000 lbf
(111 kN) afterburning) for the [Vous devez être inscrit et connecté pour voir ce lien].

Canadair Aircraft, the sub-contractor, attached the Iroquois engine to the right side of the rear fuselage near the tail; due to the large exterior diameter of the engine, no other location was feasible.

Flying the CL-52 was reportedly a nightmare.

After the Arrow project was cancelled in early 1959, the B-47B/CL-52, with about 35 hours of engine flight tests to its credit, was returned to the U.S.

Some sources claimed it was bent out of shape by the tests, but in any case, it was subsequently scrapped.

The CL-52 was the only B-47 to be used by any foreign service.

YB-47C / RB-47C / B-47Z / B-56


A four-engined variant of the B-47, the YB-47C, was proposed by Boeing in 1950 to be powered by four [Vous devez être inscrit et connecté pour voir ce lien]-A-23 turbojet engines, providing 10,090 lbf (45 kN) thrust each, in place of the six GEs J47s.

The [Vous devez être inscrit et connecté pour voir ce lien] J35 turbojet engine was being developed during the late 1940s, and it was provisionally rated at 9700
pounds (with [Vous devez être inscrit et connecté pour voir ce lien]) or 8500 pounds thrust without AB.

Thus 4 * 8500 = 34,000 pounds using that engine, as compared to 6 * 5200 = 31,200 pounds in the production B-47.

So the conversion would be lighter, simpler and more powerful.[Vous devez être inscrit et connecté pour voir ce lien]

A contract was signed with Boeing in January 1950, calling for rework of one aircraft. A B-47B-20-BW (s/n 50-082) was earmarked for the conversion.

The date for first flight was projected as April 1951.

A combination of delays and less-than-expected performance of the J35 led to the consideration of other engines.

The [Vous devez être inscrit et connecté pour voir ce lien] was proposed, however problems with this engine meant that this was not feasible for the by-then redesignated B-56A.

The [Vous devez être inscrit et connecté pour voir ce lien], eventually rated at 17,000 pounds thrust, was also considered, but that engine was still in
development, and the Boeing [Vous devez être inscrit et connecté pour voir ce lien], which was being concurrently developed (first flight was April 1952), had priority for this engine.

Allison J 71

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XB-47D


Beginning in 1951, two XB-47Ds were modified from B-47Bs as purely experimental platforms, with a big Wright YT49-W-1 turboprop engine spinning a huge four-paddle prop, replacing each of the inboard two-jet pods.

Difficulties with engine development delayed first flight of the XB-47D until 26 August 1955.

The aircraft's performance was comparable to that of a conventional B-47, and its reversible propellers shortened
the landing roll, but the USAF did not follow up the idea.

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.

Dessin sur airwar.ru

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Early production "B-47E-Is" also known featured [Vous devez être inscrit et connecté pour voir ce lien] turbojets with 5,970 lbf (27 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, increasing [Vous devez être inscrit et connecté pour voir ce lien] 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 [Vous devez être inscrit et connecté pour voir ce lien] 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.

J 47 GE 25

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B-47s rarely used JATO for takeoffs, as it was expensive and slightly more hazardous than a non-assisted takeoff.

Apparently it was reserved for emergency alerts, when bombers had to get off the runway as fast as possible, and was otherwise only done once a year or so as a training measure.

Water-methanol injection was a big help on takeoffs when JATO wasn't used.

The internal fuel capacity of initial production B-47Es was cut to 14,627 gal (55,369 l) as a weight-saving measure.

This was considered acceptable because of the use of the big external tanks and the fact that the USAF had refined mid-air refueling to the point where it could be relied upon as a standard practice.

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.

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 [Vous devez être inscrit et connecté pour voir ce lien]
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 "[Vous devez être inscrit et connecté pour voir ce lien] (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.

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.

TEE TOWN B-47E

In 1955, a number of B-47E-Is were fitted with external pods, one mounted on either side of the bomb bay, with each pod containing four AN/ALT-6B jammers.

The pods were known as "Tee Town pods" (for Topeka, KS, location of [Vous devez être inscrit et connecté pour voir ce lien]) and so these aircraft were known as "Tee Town B-47s".

They retained their normal bombing capability.