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).
Phantom II cooling tests comparing hexagonal matrix radiator tubes and the effects of ventilation on a 25-EX chassis.
| Identifier | Morton\M19\ img246 | |
| Date | 30th September 1931 | |
| To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/Lid.{A. J. Lidsey} c. Sg.{Arthur F. Sidgreaves - MD} c. WOR.{Arthur Wormald - General Works Manager} E.{Mr Elliott - Chief Engineer} c. Da.{Bernard Day - Chassis Design} RV. ORIGINAL Hs{Lord Ernest Hives - Chair}/Lid.{A. J. Lidsey}1/AD30.9.31. x7750. x766. P.II COOLING TESTS. We attach herewith results of further cooling tests in which the air temperature rise through the radiator, and the air temperature rise from the front of the radiator to the floorboards (at the pedals) were recorded. The tests were carried out on 25-EX using two radiators viz. .268" hexagonal matrix tubes and .312" hexagonal matrix tubes. A comparison of the results obtained on both types of matrix tubes shows a slight increase in air temperature rise when using the smaller tubes, from which result we should expect this radiator to be the more efficient of the two. Compared with the results obtained using 6 mm. x 7.5 mm. matrix tubes (Hs{Lord Ernest Hives - Chair}/Lid{A. J. Lidsey}/AD17.8.31) the air heat rise through the tubes is appreciably greater in the case of the hexagonal tubes. By using a thermometer placed under the floorboards near the pedals a record of the heat increase due to exhaust pipe and engine heat radiation was obtained. This increase is approximately the same whichever type of radiator is used, but will, of course, vary with the conditions under which the car is running. In all of these tests the throttle opening was just sufficient to run the car at the speeds at which readings were taken. Under full throttle conditions we should expect the increase to be considerably greater owing to the greater heat radiated from the exhaust pipes. Ventilation. The importance of efficient ventilation is shown up by a comparison of the results obtained with the bonnet on and bonnet off. Other conditions being equal the engine water temperature is reduced by 10ºC, the air temperature rise through the radiator is approximately 5º less and the floor-board heat is reduced by something like 20ºC. | ||