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).
American engine materials, supercharging technologies, and altitude-related carburetor problems.
| Identifier | ExFiles\Box 179\3\ img143 | |
| Date | 1st April 1932 | |
| -2- Use of Kelmit. Kelmit is used, or material with similar characteristics made by the Bohn Company of Detroit, by both Curtiss Wright and Pratt & Whitney. Increased clearances are necessary. Apparently these clearances have some effect on the oil consumption. No extraordinary precautions are taken to filter the oil. Pratt & Whitney use a 60 mesh filter. Wrights the pin of the crankshaft as a centrifugal cleaner with a piece of tube projecting from the oil outlet across the bore of the shaft so that sludge cannot escape until the pin is 2/3rds full. This they say takes 600 hours or so. Use of Nitro Alloy. They appear to have done very little with Nitro Alloy. They have tried cylinder-liners in it but apparently had difficulty in getting the rings to bed in. They seem to have done little or nothing on crankshafts. SUPERCHARGING. The superchargers used on Radial engines did not appear to be very efficient. One reason for this inefficiency is that the auxiliary drives have to be taken through the supercharger diffuser. Another, possibly that the temperature of the whole supercharger may be higher due to the conductivity from the air cooled engine. Wrights are using plain bearings at both ends of the supercharger rotor shaft with success. The Eclipse Aviation Co. are building a supercharger which they hope to sell as a proprietory unit. Their idea is that the ordinary built in supercharger will be used for ground boosting and their separate unit will be used for altitude work and will be fitted with a boost control which they also produce. This separate supercharger will blow through the carburetter and so overcome any difficulties of freezing up. It is fitted with a clutch and so absorbs no power up to when it is brought into operation (U.S. Patent No. 1,842629 David Gregg). The Eclipse Co. appear to be getting very good supercharger efficiencies. Carburetter freezing up and distribution troubles at altitude. Though altitude supercharging is not as well established in America as it is here, they have some very severe conditions of ice formation and to cope with this they fit various types of air intake heater. Perhaps the neatest of these is that produced by Messrs. Pratt & Whitney in which the exhaust heat from one cylinder is carried through a finned | ||