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).
Comparison of radiator tube designs, including a sample from Rolls-Royce of America, and their impact on cooling efficiency.
| Identifier | WestWitteringFiles\U\August1930-November1930\ Scan117 | |
| Date | 14th October 1930 | |
| HS{Lord Ernest Hives - Chair}/ml/A14.10.30 contd. -4- Since completing these tests we have received a sample radiator tube from Rolls-Royce of America. These tubes are hexagon ended, round centred copper tubes, 9 mm. across the flats and 7.56 mm. on the circular portion. They have twenty large indentations in them .050 -.065"/deep. From our tests on Brooklands the American P.I. was certainly adequately cooled and unless these bulges greatly increase the efficiency of the tube we do not know how they achieve the result with the size in question, which is much larger than anything we have found satisfactory. Incidentally, these indentations increase the size of the water passages appreciably. There is no doubt that radiators of the Chrysler type must promote violent air turbulence, but whether this is done intentionally or not we cannot say. We are pressing the manufacturers for delivery of the 6 mm. tubes expanded in one direction i.e. X.81389 but have not as yet received any. We anticipate that these tubes will not only reduce the weight of the radiators appreciably but should increase its cooling efficiency slightly. As will be seen from the attached curve, the hydraulic resistance of the 6 mm. square tube radiator is commendably low. We also attach curves indicating how the new radiator cap will help our circulation when the water temperature approaches boiling point. The turbulence figures may explain why radiators on which the enamel has "flaked" in the bore of the tubes in service appear to increase in efficiency. | ||