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 note on American engine developments, including superchargers, starters, reduction gears, and magnesium castings.
| Identifier | ExFiles\Box 173\1\ img186 | |
| Date | 20th January 1934 guessed | |
| -2- Super-Charger. The blower drive is taken from spur gear at front of engine through long flexible drive to supercharger, which in turn is arranged below the crank shaft centre (see sketch). Supercharging is carried out by blowing through the carburetter which is arranged between cylinders. My lowering super charger arrangement of auxiliaries is much more compact. Starting. The Americans are now adopting electric starters for all engines. Curtis Wright have been using on the Conqueror an electric starter with reduction gear ratio 30-1, 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 Jersey, who are developing this unit. Reduction Gears. Curtis are using double helical gears of .5-1 to .6-1 on development 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 favour internal reduction gear (see lower note and sketch), which indicates principal of blower drives for this type of engine. 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 magnesium has been standardised for certain castings. These are produced in their own foundry. PRATT & WHITNEY. We visited Pratt & Whitney, Hartford, and were met by Mr. Willgoos, who furnished me with type test and other data. | ||