connection to a fan stage. Instead, GE solved this problem with the addition of a completely separate fan system at the rear of the engine, powered by a new turbine stage. The system was essentially a bolt-on extension to the existing design and had almost no effect on the operation of the original engine. Each turbine blade was an integral part of a "blucket", the outboard section of which was a fan rotor blade. Running freely on a stub shaft, a series of buckets, mounted on a disc, made up the aft rotor assembly. The efflux from the turbojet expanded through the (inner) turbine annulus, thus providing power directly to the fan blades located in the outer annulus. A full-length cowl, an annular exhaust system and a bucket thrust-reverser were fitted for the Convair 990. The unique feature of the -23 was the transonic single stage fan. NACA had done a lot of research on multistage transonic compressors during the 50s. Using this data, GE decided to design and test a high-pressure ratio single stage transonic fan. Much to their amazement the unit more than met the design target, including that of high efficiency. A modified version of this research unit was subsequently incorporated into the CJ805-23 aft fan. With no experience of transonic fan design and little time available, Pratt & Whitney had to resort to using 2 fan stages to produce a similar pressure ratio for their JT-3D turbofan. Although not an overhung design, the -23 transonic fan did not require any inlet guide vanes. There was, however, a series of structural vanes to help support the fan casing. Production ends With additional changes, fuselage stretches, and the addition of anti-shock bodies, the new airliner emerged as the Convair 990. However, by this time the project had suffered several delays, allowing new versions of the DC-8 and 707 to lock up major sales. In the end, Convair sold only 102 880s and 990s in total, losing $600 million on the program. There was only one other customer for the 805-23. In 1961, Sud Aviation approached GE to pitch them on the idea of adapting the Rolls-Royce Avon powered Caravelle to the 805-23, producing a flying technology showcase for both companies. For this role they introduced a new version with a relatively short fan cowl and thrust reverser, compared to the full-length cowling on the 990. Rolls-Royce quickly built