AVRO C102 Jetliner
North America's First 1949-1956

Nacelle Shape

                 The external and internal shape of the nacelles was chosen very carefully with a view to getting the best possible pressure recovery characteristics externally, and an efficient plenum intake which would give the best compromise between the ideal low and high speed conditions, see figure 8.

                 For take-off conditions where there is very little ram effect, there is a suction in the plenum chamber, and in order to prevent breakaway around the intake walls, the wall angle was kept down to less than 10 deg. To achieve this, it was necessary to go to separate, intakes foreach engine, as with a common elliptical intake, the diffusion angle would have been excessive in a short nacelle, and any increase in nacelle length was disadvantageous, due to the destabilizing effects of a long wide nacelle.

                 The best intake curves were established in conjunction with the engine manufacturers recommendations. For the outside shape, the lines between the inside lip of the intake radius and a point about 20% of the total nacelle length aft of the intakes were most critical both for drag rise and intake effeciency, see figure 14. Figure 15 shows how little the nacelles interfere with the top surface of the wing.

 ENGINE DATA

                A civil version of the standard Rolls-Royce Derwent 5 engine is used, and a brief summary of the performance is shown below.

                Relighting in the air is possible and numerous relights have been carried out during flight tests.

                As the economy of the C-102 has been worked out assuming that all engines are operating, however, relighting would not normally be employed. It can be seen by reference to figure 16, that each engine consumes less than 90 lb. of fuel in descent from 30,000 ft. at half max. cruise r. p. m. If the operator felt, however, that any stacking should be carried out at fairly low altitude, two engines could be closed down to conserve fuel.

FUEL SYSTEM

                Fuel is housed in four integral wing tanks located in the inboard portion of the outer wings, between the main spars. The total capacity of the tanks on the first prototype is 2,400 Imp. gals. The tank capacity can, however, be considerably increased. Immersed booster pumps are used.

                 The pilot can fully control the disposition of his fuel load, and a cross balance pipe is provided so that fuel from any tank is available to all engines in an emergency.

                 In the event of failure of the booster pumps, the engines are capable of sufficient suction to enable them to operate with the booster pump inoperative.

                 Manually controlled shut-off cocks to each engine are provided as a safety measure to shut off the fuel in the event of an emergency.

                 A signal light system is provided on the, fuel system panel to enable the pilot to check instantaneously the condition of the fuel system.

                 Both overwing and underwing refueling is installed and the tanks can be refilled at the rate of 200 Imp. gals. per min. through each underwing refueling valve at a nozzle orifice pressure of approximately 5 p. s. i. A refueling manifold is used for each pair of tanks and a special built-in selector valve permits fueling or defueling of each tank individually.

                 A special float valve coupled with the underwing refueling system prevents the tank being damaged, by shutting off the fueling valve when the fuel reached a predetermined level in the tank.