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).
Weight and dimensional discrepancies in rationalised pistons supplied by Aerolite.
| Identifier | ExFiles\Box 148\1\ scan0277 | |
| Date | 18th September 1940 | |
| 1258 To Rm{William Robotham - Chief Engineer}/CTS.{C. Trot Salt - Carburation} from Rm{William Robotham - Chief Engineer}/HH. c. Rm.{William Robotham - Chief Engineer} Rm{William Robotham - Chief Engineer}/HH.3/SW.18.9.40. Rationalised Pistons. We have examined the pistons supplied by Aerolite for this range, and agree that these are heavier than was anticipated. We have weighed the 3¼ dia. piston to drawing RE.785. against a piston to EB.1299, and find a difference in weight of 2 oz. We were aware that RE.785 would be approximately ½ oz. heavier than EB.1299, as we have added .030 to the total height. Again, we have a heavier section at the top of the piston, as the ring grooves are not so deep, and number 3 against 4 on EB.1299 (being proportioned from WRAITH SERIES). We anticipated that the ½ oz. extra weight on the piston bare, would be regained in the assembly, as we only fit 3 rings against 4 on EB.1299. The pistons supplied are definitely thicker section than called for on the drawing, and we suggest that the makers be acquainted with this and have the extra weight reduced. We would point out that metal thicknesses on RE.785 should be precisely as called for on EB.1299. Rm{William Robotham - Chief Engineer}/HH. | ||