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).
Letter detailing pressure and load calculations for a carburetter needle and seat arrangement.
| Identifier | ExFiles\Box 123\1\ scan0031 | |
| Date | 20th July 1939 | |
| -2- Rm{William Robotham - Chief Engineer}/JBD.{John B. Dixon - Fuel Systems}5/JH. 20th. July, 1939. Assuming a pressure of only 3.35 lbs.sq.in. the pressure exerted on a .101 diameter seal area .0087 sq.in. = .0087 x 3.35 lbs. = .0292 lbs. If the pressure is 5 lbs.sq.in the load on the needle due to the line pressure will be 5 x .0087 = .0435 lbs. In our case the maximum pressure exerted on the seat 5.5 x .335 = 1.84 lbs.sq.in. The area of the .140" dia. seat = .0154 sq.ins. the load on the needle due to the line pressure is .0154 x 1.84 = .0284 lbs. This with the same float immersion as that for which the carburetter was originally designed gives us a better factor of safety with .140" dia. seat with the S.U. pump than the A.C. and the .101" dia. seat. We must also add that this proposed arrangement is now running satisfactorily. Yours faithfully, for ROLLS-ROYCE LTD. | ||