From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Analysis of high-altitude engine cut-out issues, comparing Antelope and Fury aircraft configurations and testing solutions.
| Identifier | ExFiles\Box 178\4\ img025 | |
| Date | 28th November 1932 | |
| An AVM Antelope with Kestrel I & 103 with a heated elbow on the blower casing, had been going up to 27,000 quite regularly; the temperature reached being in the neighbourhood of -45°C without cutting out: a question arose, "Why does the Antelope do it and not the Fury?" The Antelope having become unairworthy, its engine F 1 S 103 was installed in the Fury K.2032, and its original new engine put in the stores K I S 103 having a different gear ratio to the II's, it was necessary to get a special airscrew from Hawkers to enable it to attain the correct r.p.m. for a Fury. Several climbs were done, the same r.p.m. as a standard Fury being obtained. But the engine cut out as before, with the heated elbow in use 30,000 ft - 46°C was reached, with the elbow bypassed 22,000 ft - 36°C was reached i.e. 18°C cooler air temp with the elbow in use. It was then noticed that the only difference between the Antelope and the Fury was: the Antelope did its climb at more r.p.m. at 22,000 ft than the Fury. An AVM Antelope Airscrew was fitted to the Fury, enabling it to do the same r.p.m. This resulted in the machine climbing to its ceiling 28,500ft - 51°C with F.S. A/C being used, and no cutting out of the engine. This was done without the heated elbow in use. A repeat climb was done to 28,000 ft and - 49°C being reached. A series of partial climbs were done at 24,000 ft during the same flights; these were done at different r.p.m. in order to see at what revolutions the engine cut out. A partial at 2250 r.p.m. the engine was smooth. " " 2200 " " " rougher. " " 2150 " " " cut out. This proved that the increase in r.p.m. was the cure. When the low revving airscrew was fitted and the machine was climbing at 2150 r.p.m. an A/C could be used but when the machine was level and the r.p.m. increased to 2250 F.S. A/C could be used. This was at 24,000 ft or just before the engine cut out. This led us to believe that the petrol: it was assumed that the correct mixture was being delivered by the carburettor, was building up, and draining into the blower at the lower r.p.m. and thus causing richness at the cylinders, made apparent by this inability to use A/C and that the higher r.p.m. attained on the level kept the petrol moving and not draining back to the blower thus allowing the mixture to become more correct and the A/C could be used. | ||