The Rolls-Royce RB.37 Derwent is a 1940s British centrifugal compressor turbojet engine, the second Rolls-Royce jet engine to enter production. It was an improved version of the Rolls-Royce Welland, which itself was a renamed version of Frank Whittle's Power Jets W.2B. Rolls-Royce inherited the Derwent design from Rover when they took over their jet engine development in 1943. Design and development Rover When Rover was selected for production of Whittle's designs in 1941 they set up their main jet factory at Barnoldswick, staffed primarily by Power Jets personnel. Maurice Wilks was also aware of the potential of a more efficient straight-through design. This layout had already been used by Whittle in his drawings of the W2Y and W3X and was also being pursued by the de Havilland Company with the Halford H.1. Wilks set up a design office at Waterloo Mill, Clitheroe with Adrian Lombard leading the design of an engine with this configuration. The design was done in secret and was sanctioned by the Ministry of Aircraft Production (MAP) but Whittle believed all effort should have been directed towards flight testing of the reverse-flow engine. While work at Barnoldswick continued on what was now known as the W.2B/23, Lombard's new design became the W.2B/26. Lombard went on to become the chief engineer of the Aero Engine Division of Rolls-Royce. Rolls-Royce By 1941 it was obvious to all that the arrangement was not working; Whittle was constantly frustrated by what he was seeing as Rover's inability to deliver production-quality parts for a test engine, and became increasingly vocal about his complaints. Likewise Rover was losing interest in the project after the delays and constant harassment from Power Jets in the critical testing process stage, where testing new designs and materials to breaking point is vital. Earlier, in 1940, Stanley Hooker of Rolls-Royce had met with Whittle, and later introduced him to Ernest Hives. Rolls-Royce had a fully developed supercharger division, directed by Hooker, which was naturally suited to jet engine work. Hives agreed to supply key parts to help the project along. Eventually, by mutual agreement between the Minister of Aircraft Production and the boards of Rover and Rolls-Royce, the Rover jet factory at Barnoldswick was exchanged for the Rolls-Royce Meteor tank engine factory in Nottingham. Subsequent Rolls-Royce jet engines would be designated in an "RB" series, the /26 Derwent becoming the RB.26. Problems were soon ironed out, and the