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).
The performance comparison between original and modified oil cooler matrices for the Spectre Oil Temperature Regulator.
| Identifier | ExFiles\Box 131\1\ scan0135 | |
| Date | 22th August 1935 | |
| 11145 X500 To E.{Mr Elliott - Chief Engineer} c. to Wor.{Arthur Wormald - General Works Manager} c. to By.{R.W. Bailey - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Swdl.{Len H. Swindell}2/KW. 22.8.35. SpectreCodename for Phantom III Oil Temperature Regulator. From tests carried out under identical conditions we have found that the original type of matrix (Lec.3756) is more efficient than the modified matrix Lec.4386 which has larger tubes and increased oil passages to reduce the back pressure. Running at 4000 r.p.m. and maintaining a constant oil inlet temperature to the cooler of 100°C. the outlet with the original matrix was 89°C., and 93°C. with the modified matrix. The removal of the water baffle plate from the underside of the matrix did not alter these temperatures by more than ½°C. These figures, although directly comparable, are not the true actual figures as they were taken with the original crankcase and small pump which necessitates keeping the inlet water temperature lower than would be the case with an up-to-date crankcase and pump. They however justify Hancock's report in an increased oil temperature since fitting the modified matrix. In the case of the original matrix, the pressure before cooler when running at 4000 r.p.m. and 100°C. is 40 lbs/sq.in. and 34 lbs/sq.in. after the cooler, in comparison with 38 lbs/sq.in. and 34 lbs/sq.in. with the modified matrix. Starting from cold at an oil temperature of 20°C. and running at 750 r.p.m. the pressures before and after the cooler are 70 lbs/sq.in. and 50 lbs/sq.in. with the original matrix and 60 lbs/sq.in. and 50 lbs/sq.in. with the modified matrix. Several of the original type have burst at the unsupported soldered seams, and would be much stronger if a ribbon binding arrangement of the complete tubes be used, similar to the Buick cooler. | ||