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).
High-altitude engine performance issues, including fuel distribution and freezing, with proposed solutions.
| Identifier | ExFiles\Box 179\2\ img027 | |
| Date | 9th December 1931 | |
| -2- Hs{Lord Ernest Hives - Chair}/Lov.{Mr Lovesey}1/MJ.9.12.31.Cont'd.{John DeLooze - Company Secretary} port side cylinders and any attempt to reduce this with the A/C. results in a "cut out". The starboard cylinders remain quite normal. This is quite in agreement with our tests on the 111F. up to 2,000 ft. Unfortunately this represents about the ceiling of the 111 F.{Mr Friese} with the moderate supercharged 'Kestrel' On our last climb on the 111 F.{Mr Friese} to 20,000 ft. we reached a temperature of -35°C. and had to use full A/C. Returning the A/C. to full strong resulted in the front port cylinders ceasing to fire and the mixture issued from these cylinders in wet spray which immediately formed a long trail of snow behind the machine. These results appear to indicate that the trouble can be a combination of two causes:- (a) Bad distribution at low temperatures with a preference of the front three port cylinders to receive the wet fuel and, (b) Freezing in the diffuser indicated by the necessity for running full rich. The symptom of having to run full rich is a characteristic of bad distribution but the small improvement which resulted when the petrol filter was heated - enabling a few degrees lower air temp. to be reached - indicates diffuser freezing. The small amount of heat in the petrol could not influence distribution at these low temperatures. It seems reasonable to assume that inside air intakes would be at least a partial solution to the above two causes and allow an increase in altitude and lower air temperature before encountering the trouble. An alternative is to incorporate a small honeycomb radiator in each air intake fed by a shunt from the normal radiator system. Taking the air in through the radiator as suggested by R.{Sir Henry Royce} some time ago would appear ideal except that in this particular machine it would mean very long air intakes. Heating the air would appear the simplest and quickest way of getting existing engines serviceable for high 'altitude' flying. Experiments with modified induction systems cannot be done very quickly as the development in this direction is largely a matter of trial and error. We should however only regard such a scheme as a temporary relief and the ultimate solution should lie in the induction system and carburetter heating. With that | ||