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 to F.M. Aspin comparing the breathing capacity of his Aspin valve against the standard poppet valve for aviation engines.
| Identifier | ExFiles\Box 134\1\ scan0224 | |
| Date | 28th June 1940 | |
| Rm.{William Robotham - Chief Engineer}6/JMS. 28.6.40. F.{Mr Friese} M.{Mr Moon / Mr Moore} Aspin, Esq., Messrs. F.{Mr Friese} M.{Mr Moon / Mr Moore} Aspin & Co. Ltd., Elton, BURY. Dear Mr. Aspin, Thank you for your letter of June 14th. We have now compared the valve opening diagram which we are getting on our existing up-to-date engines with your improved porting. Even in it's altered condition, the Aspin valve is so much down in breathing capacity over our normal practice with the poppet valve that we can hardly believe it could be employed without excessive power loss at the peak of the curve. Briefly, therefore, the situation is this: Unless you can demonstrate that the Aspin valve, through an improved orifice co-efficient, has a better breathing capacity for a given valve opening diagram than the corresponding poppet valve, we shall not be sufficiently interested to go ahead on aviation work. Really, therefore, one of the most useful things you could do would be to compare the overhead poppet valve engine with an Aspin valve engine of the same valve opening diagram. Yours sincerely, | ||