Northrop YB-49


The second and third YB-35 pre-production prototypes were converted into YB-35B aircraft. Their four 3250-hp (242 3-kW) Pratt & Whitney R-4360 piston engines were replaced by eight 4000-lb (1814-kg) thrust Allison J35-A-5 turbojets, four jets being grouped in each trailing edge and aspirated through the same arrangement of leading-edge inlets used to supply carburation and cooling air for the piston engines of the original aircraft.

The YB-35B was redesignated YB-49 while it was being rebuilt, and the first aeroplane flew on 21 October 1947. The second had six 2540kg thrust Allison engines, four buried in the wings and two in underslung pods to increase the volume available for fuel.

Speed was increased dramatically from 393 to 520 mph (632 to 837 kph), but such was the thirst of the turbojets that range was halved. There were also several control problems that made the type unsuitable for use as a free-fall bomber, and it was decided to transform the type into a strategic reconnaissance aeroplane.

In June 1948 the second YB-49 was destroyed with the loss of its five man crew in a crash attributed to structural failure.

Confidence ran high, and the USAF ordered 30 YRB-49s for the long-range reconnaissance role, one of which was to be built by Northrop and, because of that company's other commitments, 29 by Consolidated Vultee. Even the fatal in flight breakup of the second prototype in March 1950 failed to dampen spirits. The RB-49 offered no real advantages over the B-47 and the new B-52, production was cancelled before the single YRB-49 flew on May 4, 1950.

The YB-35 programme continued for a while with various test airframes, but in October 1949 the whole programme was cancelled and the aircraft were scrapped. The YB-49 made a flag-waving trip from Edwards Air Force Base in California to Washington, D.C. at 823 kph (511.2 mph), 160 kph (100 mph) faster than the favoured B-36, but it was too late.

Sole survivor was the six-jet YB-49A, but just four years later this was broken up.

Engines: 8 x Allison J35-A-2, 1814-kg (4000-lb) thrust.  
Engines: 8 x Allison J35-A-15, 1800kg
Max take-off weight: 96800 kg / 213409 lb
Wingspan: 52.4 m / 171 ft 11 in
Length: 16.2 m / 53 ft 2 in
Wing area: 372 sq.m / 4004.17 sq ft
Max. speed: 930 km/h / 578 mph
Range: 8700 km / 5406 miles
Crew: 6

Engines: 6 x Allison J35 turbojets, 1870kg
Wingspan: 52.4 m / 171 ft 11 in
Length: 16.2 m / 53 ft 2 in
Wing area: 372 sq.m / 4004.17 sq ft

Northrop YB-49



Northrop YRB-49