Altitude-chamber performance of British Rolls-Royce Nene II engine 1: standard 18.75-inch-diameter jet nozzle Page: 3 of 60
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2 NACA RM E9123
INTROGUTION
Because of the design differences of the British Rolls-Royce
Nene II engine as compared with similar American turbojet engines
and because of the high sea-level rating, an altitude performance
investigation of a Nene II engine was conducted in an altitude
chamber at the NACA Lewis laboratory during 1948.
The effect of altitude and flight speed on the over-all engine
performance, using the standard 18.75-inch-diameter jet nozzle, is
presented herein. Results are presented for simulated conditions
varying from sea level to an altitude of 60,000 feet and for ram-
pressure ratios from 1.00 to 3.50. These ram-pressure ratios cor-
respond to flight Mach numbers from 0 to 1.47, assuming 100-percent
ram-pressure recovery. The conventional method of reducing data to
sea-level conditions referencee 1) was used to determine whether
performance could be generalized; that is, whether data at one
altitude and ram-pressure ratio could be used to predict performance
at other conditions of altitude and ram-pressure ratio.
INSCRIPTION OF POWER PLANT
A cutaway view of the British Rolls-Royce Nene II power plant,
which is a through-flow turbojet engine having nine combustion
chambers, is shown in figure 1. The engine incorporates a single-
stage double-entry centrifugal compressor (tip diameter, 28.80 in.)
driven by a single-stage reaction turbine (tip diameter, 24.53 in.).
The turbine-nozzle area is 126 square inches and the jet-nozzle
area is 276 square inches. The dry engine weight is approximately
1720 pounds (starting panel and generator included) and the maximum
diameter (cold) is 49.50 inches, giving an effective frontal area
of 13.36 square feet.
The sea-level engine performance (reference 2), based an Rolls-
Royce static test-bed data, is:
Rating Jet thrust Rotor speed Specific fuel
(lb) (rpm) consumption
(lb/(hr)(lb thrust))
Take-off 5000 12,250 1.04
Military 5000 12,250 1.04
Max. cruise 4000 11,500 1.02
Idle 120 2,600 ----
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Barson, Zelmar & Wilsted, H. D. Altitude-chamber performance of British Rolls-Royce Nene II engine 1: standard 18.75-inch-diameter jet nozzle, report, September 23, 1949; (https://digital.library.unt.edu/ark:/67531/metadc58334/m1/3/: accessed April 19, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.