The Rolls-Royce RB.41 Nene is a 1940s British centrifugal compressor turbojet engine. The Nene was a complete redesign, rather than a scaled-up Rolls-Royce Derwent with a design target of , making it the most powerful engine of its era. It was Rolls-Royce's third jet engine to enter production, and first ran less than 6 months from the start of design. It was named after the River Nene in keeping with the company's tradition of naming its jet engines after rivers. The design saw relatively little use in British aircraft designs, being passed over in favour of the axial-flow Avon that followed it. Its only widespread use in the UK was in the Hawker Sea Hawk and the Supermarine Attacker. In the US it was built under licence as the Pratt & Whitney J42, and it powered the Grumman F9F Panther. Its most widespread use was in the form of the Klimov VK-1, a reverse-engineered, modified and enlarged version which produced around of thrust, and powered the famous Mikoyan-Gurevich MiG-15, a highly successful fighter aircraft which was built in vast numbers. A higher thrust version of the Nene was produced as the Rolls-Royce Tay. Design and development The Nene was designed as a result of a June 1944 visit to the US by Hooker. He was surprized to learn that General Electric already had two engine types running, an axial and a centrifugal, of thrust. He was determined to produce a higher thrust engine and subsequently obtained a Ministry of Aircraft Production contract for an engine of 4,200 lbf (19 kN) thrust with the understanding that would be the design target. Hooker, Lombard, Pearson and Morley designed a new engine, the B.41 later called the Nene, rather than scaling up the Derwent. The double-sided impeller was in diameter, compared to for the Derwent I, to produce an airflow of , while the overall diameter of the engine was . A scaled up Derwent of the same thrust would have had a diameter. The compressor casing was based on Whittle's Type 16 W.2/500 compressor case which was more aerodynamically efficient than that on the Derwent but also eliminated cracking. Other design advances included nine new low pressure-drop/high efficiency combustion chambers developed by Lucas and a small impeller for rear bearing and turbine disc cooling. The first engine start was attempted on 27 October 1944. A number of snags delayed the run until