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).
Requesting a design and details for a raised crown piston to be compared against an Aerolite version.
| Identifier | ExFiles\Box 99\4\ scan0121 | |
| Date | 17th August 1938 | |
| 436 also 1250. Da.{Bernard Day - Chassis Design} From Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} c. Da{Bernard Day - Chassis Design}/McS. c. By/CS. Rm{William Robotham - Chief Engineer}/Swdl{Len H. Swindell}1/R.17.8.38. Will you please issue a design and details for a raised crown piston which otherwise is as the standard split skirt piston 25/30 (E.61463.) This will be used to compare against similar raised crown pistons ground for us by the Aerolite people out of our 25/30 castings, the skirt however being left solid. The object of the above is to retain the same cylinder head on B.III as on Wraith III and yet by means of the raised crown have a compression ration of 6.5 on the former and 6 on the latter. Attached is a sketch Rm.{William Robotham - Chief Engineer}522 of the raised crown piston to which experimental pistons have been produced for us. The present Aerolite piston as used on production weighs 19 ozs and the R.R. 20 ozs, and we should like the new raised crown R.R. pistons you design, if possible without sacrifice to their strength, to weigh not more than 19 ozs. Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} | ||