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).
Resolving fuel/air distribution issues in supercharged Kestrel engines at high altitudes and low temperatures.
| Identifier | ExFiles\Box 179\2\ img124 | |
| Date | 5th January 1932 | |
| To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/Lov.{Mr Lovesey} c. to Sg.{Arthur F. Sidgreaves - MD} Wor.{Arthur Wormald - General Works Manager} c. to RE. R.{Sir Henry Royce} c. to By.{R.W. Bailey - Chief Engineer} Lp.{Mr Lappin} c. to ME. Lr.{Mr Ellor} c. to Mr.Jaques. ORIGINAL X1908 x3933. Hs{Lord Ernest Hives - Chair}/Lov.{Mr Lovesey}9/ET.5.1.32. DISTRIBUTION AT HIGH ALTITUDES AND LOW AIR TEMPERATURES. Distribution troubles and "cutting out" at high altitudes on supercharged Kestrel engines have not so far been overcome by modified mixture pipes and improvements to the redistributor. The fact that the operation of these engines is without complaint at low altitudes and moderate air temperatures, indicates that probably the most straightforward method of overcoming the trouble is by warming up the air at the carburetter intakes. We have proved definitely that it is the very low air temp. that is the cause of the distribution trouble, and not an altitude effect, because we have been on the Fairey J.F. when the air temp. has been -20°C and obtained quite reasonable operation, but when at this altitude the air temp. has fallen to -35°C the engine has operated very erratically and some cylinders would not fire at all, due to an excess quantity of the wet mixture passing through these cylinders. We have now tested out, at high altitudes, the small water heated honeycomb radiators fitted in the carburetter air intakes with very successful results. These air heaters were built up from standard Phantom II radiator tubes, being 7 mm by 4 inches long, fitted to each of the two air intakes, close to the carburetter. The normal venturi intakes were used outside the cowl. A sketch of the heaters and piping system is shown on appended prints. On the test bench these heaters gave a temp. increase to the air across them of 12°C. On the test bench there was a small power drop using these intakes compared with standard, due partly to the temp. and partly to restriction, but the total only amounted to about 3%. We are arranging to further investigate this loss but first thought it essential to test for distribution improvement in the air. These were fitted to the Fairey J.F. and a climb made to 20,000 ft. The general running of the engine on the whole climb was improved, resulting in appreciably smoother operation. At 20,000 ft. the air temp. had fallen to -38°C, and the engine would still operate well, even with the A/C at full rich. On a previous climb with standard unheated intakes and an air temp. of -33°C, only about half the cylinders would fire with | ||