without tail section, showing its Rolls-Royce Nene II turbojet The Nene was designed as a result of a June 1944 visit to the US by
Stanley Hooker. He discovered 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,
Adrian Lombard, Pearson and Morley designed a new engine, the B.41 later called the Nene, rather than scaling up the Derwent. The first engine start was attempted on 27 October 1944. A number of snags delayed the run until nearly midnight, when with almost the entire day and night shift staff watching, an attempt was made to start the engine. To the frustration of everyone with a vested interest in it starting the engine refused to light - positioning the igniter was a trial-and-error affair at the time. On a subsequent attempt, Denis Drew, who had come from Lucas, the combustion specialists, and took a wide interest in engine development problems, removed one of the igniters and instead used the flame from an
oxy-acetylene torch to ignite the fuel in the combustion chamber. The igniter had to be close enough to the fuel spray to ignite it when starting, but not overheat when subjected to the continuous flame temperature when the engine was running. The larger diameter of the Nene combustion chambers found this to be a problem, and the first-run needed to ignite with a flame rather than the spark energy that was considered sufficient at that time. The Nene was subsequently fitted with two torch, or flame, igniters which had a fuel spray next to an igniter. The flame would project into the main combustor fuel spray. Torch igniters were superseded by surface discharge igniter plugs with a considerably greater energy release rate than a flame. The engine was run up to just over , and a cheer went up around the assembled personnel. However the engine was running hotter than expected and would not reach 5,000 lb, as it was built, without overheating the turbine. Pearson, the performance engineer, insisted that no more running be done without fitting the guide vanes that were available for the impeller intake. Upon Hooker's arrival next morning, and informed that the inlet vanes had been fitted during the night, Hooker was overjoyed to see the thrust gauge needle registering at the same temperature that had only given 4,000 lb the previous night, making the B.41 the highest thrust jet engine in the world. Weight was around . Inlet guide vanes had been in use in Whittle engines for some time. They improve the overall performance of the engine significantly by "helping the air round the corner". However they were made from thin sheet metal and often broke damaging the engine. For Hooker they were a worrying mechanical problem which he did not want so they were not fitted when the Derwent entered service, although the turbine had to run 90 degC hotter to give the take-off thrust of 2,000 lb. He was still concerned with the durability of the vanes so the first Nene was initially built without them. The Nene was based on the "straight-through" version of the basic
Whittle-style layout, with the flow going directly through the engine from front to rear, as opposed to a "reverse-flow" type, which reverses the direction of air flow through the combustor section so that the turbine stage can be mounted within the combustor section; this allows for a more compact engine, but increases the combustor pressure losses which has an adverse effect on engine performance. Less thrust is generated with the same fuel flow. It was during the design of the Nene that Rolls decided to give their engines numbers as well as names, with the
Welland and
Derwent keeping their original
Rover models,
B/23 and
B/26. It was later decided that these model designations looked too much like RAF bomber designations (i.e. "
English Electric Canberra B.Mk 2" would often be shortened to "
Canberra B.2"), and "R" was added to the front, the "R" signifying "Rolls" and the original Rover "B" signifying
Barnoldswick. This
RB designation scheme continued into the late 20th Century, with
turbofan designs such as the
RB.199,
RB.203 and
RB.211; the most recent family of Rolls-Royce turbofans (a development of the RB.211) goes under the simple designation "
Rolls-Royce Trent", with variants given their own designator number or letter series (i.e.
Trent 500,
Trent 900,
Trent 1000,
Trent XWB, etc.). Early airborne tests of the Nene were undertaken in an
Avro Lancastrian operated by Rolls-Royce from their Hucknall airfield. The two outboard
Rolls-Royce Merlins were replaced by the jet engine. The Nene's first flight however was in a modified
Lockheed XP-80 Shooting Star. After seeing the Nene running, at an after work drink at the
Swan & Royal Hotel,
Clitheroe, and hearing the complaints about a lack of any official application for the engine, someone - thought to be
Whittle - suggested that the Nene be scaled-down to fit a
Meteor nacelle. J.P. Herriot or Lombard did the calculation on a tablecloth and announced a thrust of . At this time they were attempting to increase the Derwent's thrust from , and the idea seemed "too good to be true". On hearing this, Hooker did a quick calculation and announced, "We've got a 600-mph [] Meteor". Drawings for the 0.855 scale Nene, now known as the Derwent V, were started on 1 January 1945 and on 7 June the engine began a 100-hour test at , soon reaching . Weight was . By 1946 thrust had been increased to using
Nimonic 90 turbine blades. The development of the Nene was continued with this scaled-down version, the Derwent V having no direct relationship to the earlier Derwent series. On 7 November 1945, the first official air speed record by a jet aircraft was set by a Meteor F.3 of 606 miles per hour (975 km/h) powered by the scaled-down Nene. ==Service use==