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Aviation History
1946
1946 - 0236.PDF
132 FLIGHT FEBRUARY 7TH, 1946 RIVER CLASS" EVOLUTION 850 lb. weight. It flew in the Gloster E.28, and after further development it was conservatively rated at 1,450 lb. thrust and became the power unit for the twin-engined Meteor prototype, the Gloster F9/40. In addition to producing the improved B.23 design from the W.2B, the Rover Company produced a unit with con- siderably modified layout, which they called the "straight- through " engine. Hitherto, contra, or reverse-flow, combustion chambers had been employed but, in the new conception, combustion chambers were arranged with inlet towards the front of the engine and outlet directed rear- wards into the discharge nozzle in front of the turbine. Although some merit might still be found in the original reverse-flow layout, the straight-through design at once showed considerable promise. While the overall diameter was unchanged, a rather more compact engine resulted, and there was no restriction on turbine diameter. Designated the Rover B.26, this unit, together with the Power Jets W.2/500, formed the basis of the Rolls-Royce B.37 or Derwent. As will be appreciated from a com- parison of power ratings, the intro- duction by the Rover Company of the straight-through combustion system constitutes a most important feature in recent gas turbine de- velopment. Meteor Power Units By 1944 the Meteor with Wclland engines had reached squadron stage in the R.A.F., and with a clear 25 m.p.h. speed margin over any other Allied military aircraft made a timely addition to our flying-bomb defences. The Derwent, the second River- class engine, had by this time been further developed by Rolls-Royce and, as stated, the main difference lay in the adoption of straight- through combustion. Subsequent marks of the Derwent, the II and ' IV, each showed about 10 per cent, thrust increase over the designed 2,000 lb., and the Derwent V, which later powered the record-breaking Gloster Meteors, passed the official FIXED NOZZLE GUIDE VANES TURBINE BLADES CA&YRINTH/ SEAL RING The combustion chamber seatings at the front of the dischargenozzle. Cooling-air pipes.may also be seen. Turbine guide vanes on the rear side of the discharge nozzleassembly. 100-hr, type test at a rating of 3,000 lb. thrust. As an indication of simplicity of design as compared with the piston engine, it is note- worthy that the complete Der- went V, which is somewhat different from the earlier Derwents, was pro- duced straight from the drawing board, and it was the first-engine- off that passed the type test. Since that time the Derwent V has under- gone intensive development and now gives 4,000 1b. thrust. Derwent V Details The Derwent V is, in effect, a scaled-down version of an improved scaled-up Derwent I layout/ The larger unit, the R.B.-4I, is at present being developed to meet a single-seater fighter specification calling for a minimum of 4,000 1b. thrust, an installed weight of 2,200 1b. .and a maximum diameter of 55m. More will be said of this power unit later. The Derwent V was prompted by the great promise shown by the larger design and because the Meteor had shown itself capable of utilising thrust greatly in excess of the original estimates. Intensive work resulted in the designing, .building and test- ing of a new Derwent in just under six months. Subse- quently it resulted in the establishment of a new world's air-speed record of 606 m.p.h. Certain details of construction could not be mentioned when the original Derwent and its development was described in Flight of October 25th, 1945. These are now worthy of review- and comparison with Derwent V compon- ents. It may be assumed that most of the detail improve- ments will be featured in the larger engine series. A radial compressor of increased capacity is, perhaps, the most important single modification. This is of the double-entry type as on all Derwent engines, but, on the V, the main shaft coupling compressor and turbine is mounted in two roller bearings and a central ball thrust bearing instead of plain bearings. The central ball bearing adjacent to the shaft coupling provides a definite axial location and sup- ports the axial thrust of .the turbine rotor. It is of a The rear bearing andturbine disc are cooled by air froman auxiliary fan. This section is ofDerwent I compo- nents.
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