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).
Technical report on American aero-engine developments, including starter motors, gears, materials, and testing procedures.
| Identifier | ExFiles\Box 173\1\ img175 | |
| Date | 20th January 1934 | |
| H.{Arthur M. Hanbury - Head Complaints} S. from R.{Sir Henry Royce} H.{Arthur M. Hanbury - Head Complaints} C. - 2 - 80-1, but are now experimenting with direct drive starter motors. They consider that since for other reasons engine must be kept warm and oil pre-heated, there is no reason why, particularly since night flying has developed and large batteries are necessary, direct starting should not be successful. I will obtain latest information of Starter Motors from Eclipse Corp. New Jersok who are developing this unit. Reduction Gears Curtis are using double hellical gears of .5-1 to .64-1 on development of engines, but, owing to position of liquid cooled engines mentioned in my previous notes, these gears have only been fitted to development engines, and so far have proved satisfactory. Allison's favor internal reduction gear (see lower note and sketch), which indicates principal blower drives for point type of engine. THIS TRIPL Magnesium Castings These are gradually being adopted on the new type engine with improved cylinder construction. Curtis are testing crank cases, rocker covers, wheel cases and most of smaller type castings in this material. On the Wright air cooled engines the magnesium has been standardised for certain castings. These are produced in their own foundry. PRATT AND WHITNEY We visited Pratt & Whitney, Hartford, and were met by Mr. Willgoos, who furnished R.M. with type test and other data. Valves Sodium cooled valves, which are supplied by Wilcox-Rich, are used and do not give trouble, but so far these valves have run with 2-2½° lead. Lead Bronze This is used with big end bearings, and is supplied by Allison's and Bohn's. Both types are reported to give good results (but this does not coincide with Curtis Wright experience of Bohn bearings). There does not appear to be any fixed form of high speed test. P & W conditions consist of running an engine up to normal power and speed, relieving load to obtain 30% over speed, which is run in thirty second periods, restored to normal conditions for two minutes and repeated twenty times. This test is P & W's interpretation of the high speed test, and whilst the authorities do not stipulate conditions of test, they prefer for their own benefit to carry out test stated which is approved by the government inspector. SUFFICIENT? Magnesium Many large castings are produced in magnesium, which is supplied by the Aluminum Company of America, Cleveland, who also supply aluminum castings. Overhauls All P & W engines are now running 350 hours between overhauls, general condition | ||