The second prototype XB-29, serial 41-003, around the time it made its maiden flight on December 30, 1942. Its loss on February 18, 1943, when it suffered an engine fire and crashed into the Frye Meat Packing Plant, was a severe blow to the B-29 programme, and thwarted British plans to send an RAF operational crew to appraise the type.

Boeing Washington B.1 WF509 of No 44 Sqn at Marham in February 1951. Formerly serial 44-62003 in USAAF service, this was one of the 92 B-29s loaned to the RAF as an interim measure between its ageing Avro Lincolns and the new generation of jet bombers. The Washington’s RAF frontline career was short, the majority having been returned to the USA by early 1954 following the introduction of the English Electric Canberra into RAF Bomber Command squadrons.

The third and final XB-29, serial 41-18335, up on a test flight from Seattle after its first flight in June 1943. It was later flown to Boeing’s factory in Wichita, Kansas, as a pattern model for the assembly line there.

The first prototype XB-29, serial 41-002, made its maiden flight on September 21, 1942, from Boeing Field in Seattle, with no armament fitted and powered by four Wright R-3350 engines driving three-bladed propellers; production examples incorporated four-bladers. Used as a test aircraft throughout the war, it was scrapped in 1948.

This rare sequence of photographs shows mock-up gun turrets fitted to a B-29 mock-up fuselage, all showing prospective manned turrets, corresponding largely to the RAF’s Version C. Clockwise from top left: upper front turret; upper rear turret; lower rear turret facing aft, and lower front turret facing aft.

A scale comparison of the size of the Windsor and B-29. The length of the B-29 was 99ft (30-18m) and its span was 141ft 21/2in (43-04m) as against the Windsor’s 117ft 2in (35-71 m).

Version A. We believe this to be the most likely option to appear in RAF markings. The central fire-control system would be retained along with the general changes
Version B. A much stripped-down concept. The central fire-control system and sighting stations would not be installed and the turrets replaced by a significantly reduced number of manned turrets, specifically the Martin A-3D top turret in the forward upper position and a Sperry ball turret in the rear ventral position. The latter would provide both a spotting and armed station to drive off nightfighters attacking from below and behind. The tail armament remains the same as Version A. This version would have allowed substantial lightening of the airframe, with a subsequent increase in range, speed, bombload and crew numbers
Version C. The final armament iteration for the prospective RAF B-29 incorporates four manned turrets (in addition to the tail position). The USAAF’s standard upper remotely-operated turrets would have been replaced by Martin A-3D manned 0-50in turrets, and the standard underside turrets would have been replaced by Sperry 0-50in ball turrets. The H2S radar would have been mounted between the bomb bays and both the central fire-control system and pressurisation equipment would have been deleted

The Vickers Wellington Mk X was the ultimate bomber variant of the type, built at Vickers’ Chester and Blackpool factories. The Mk X entered RAF service in 1943, by which time the type’s career as a frontline bomber was drawing to a close, Bomber Command’s four-engined heavies having taken over the primary bombing role.

Designed to the same US Army Air Corps Specification, XC-218-A, as Boeing’s XB-29, the Consolidated XB-32 drew on the company’s experience with the B-24 to create a four-engined twin-finned pressurised bomber with remotely-controlled retractable gun turrets. This is the second prototype XB-32, serial 41-142, in early 1944.

Built to Air Ministry Specification B.3/42, the prototype Vickers Windsor, DW506, made its first flight at Farnborough in the hands of Joseph “Mutt” Summers on October 23, 1943, powered by four 1,635 h.p. Rolls-Royce Merlin 65 engines. Note the unusual undercarriage featuring a single mainwheel in each of the engine nacelles.