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).
Tests on piston clearance and splitting pistons to reduce noise and optimize skirt flexibility.
| Identifier | WestWitteringFiles\N\2October1925-December1925\ Scan3 | |
| Date | 1st October 1925 | |
| R.R. 493A (50 H) (D.D. 31, 12-6-25) J.H.D. EXPERIMENTAL REPORT. -3- Expl. No. REF:- ACL/LGS.10.25. Even with this increased clearance .003 to .004, there was no evidence of piston slap when cold. We have also tried pistons with the clearance increased to .004 to .005" but with no better results. Another experiment we tried was to split the pistons on both the pressure and non-pressure sides in exactly the same way as the non-pressure side is at present split. The results were very satisfactory and no knock was evident either when starting from cold or when the engine was hot. These pistons however rattled at high speeds due to, no doubt, the increased flexibility causing the piston to 'spring' when subjected to greater side thrust. Our experiments seem to show that we want a more flexible skirt having a fairly good contact surface but not so flexible that we get rattle at the high speeds. The course we are now following is to increase the flexibility of the skirt. Hs{Lord Ernest Hives - Chair}/ACL | ||