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).
Continuation of a letter discussing engine knock testing equipment and procedures.
| Identifier | ExFiles\Box 165\4\ img158 | |
| Date | 1st July 1932 | |
| CONTINUATION 1 PAGE 2 DATE 1.7.32 that no two microphones are alike, but, again, the differences should not be great, and could be allowed for by calibrating each microphone against any selected microphone to determine differences due to diaphragm gap etc. The standard selector mechanism would be suitable, without modification, for examining each cylinder in turn for shock due to combustion, a small angle of listening being used and this angle phased round the crankshaft to come into phase with each firing stroke in succession. As regards setting up, it is only necessary to arrange for a half inch diameter shaft drive from the engine camshaft and to couple the selector to this by means of a piece of canvas hose and two small bolts. The selector is held from any suitable support, and sufficient length of lead is supplied for connection to the output meter box at some distance away. The amplifier is an all-mains type for any A.C. voltage in general use. Our C.F.R. knock testing engine is on rail between here and London and should come in at any time. It will be three or four weeks before we are ready for running it as there are various items of switchgear to be made yet. I will let you know as soon as it is ready, but if you care to come over to see the strobophonometer again in the meantime I should be very pleased to show you the apparatus in routine use on a single cylinder fuel testing engine of the Armstrong type - the multi-cylinder engines are too fully occupied on long duration tests at the moment. The instrument is made by R.M.Radio Ltd., of 19 Carrick Street, W.C.2. Yours sincerely, [Illegible Signature] | ||