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).
Report from Harrison Radiator Corporation discussing engine cooling system performance and design considerations.
| Identifier | ExFiles\Box 149a\3\ scan0178 | |
| Date | 18th August 1936 | |
| HARRISON RADIATOR CORPORATION LOCKPORT, NEW YORK August 18, 1936 - 3 - the cooling resulted in the equivalent of 1" added in thickness of the radiator core. With the cowl at the rear of the core, it is not possible to get satisfactory results unless the fan can be placed quite an appreciable distance away from the back face of the core so that the angle of the corners of the shroud will not be too great and so interfere with airflow. In any case, we have found that these cowls at the rear of the core are only of assistance at slow speeds. We have found that when the fan is close to the core, that the cooling at slow speeds, (that is at 20 MPH full load) can be improved about 5°F.{Mr Friese} by fitting a ring approximately 1" larger in diameter than the fan to the back face of the core. This ring being of only sufficient depth to extend to the leading edge of the fan blades. Referring to page 3 in addition to the size and speed of fans influencing the idle of the engines after the car has had a fast run, we have found over here that a very vital factor is the amount of water which is in the jacket (that is the thickness of the water space). We have found that it is extremely difficult in the Foundry to get a satisfactory jacket that has cores less than 3/8" thick, these cores being placed at the side of the bores and we have also found that it is extremely beneficial to have a minimum space of 1-1/2" over the exhaust valve ports for water. Among other things what happens is that after a fast run the iron has an appreciable amount of residual heat and if the water thicknesses are too small to carry this heat off, at the comparatively sluggish circulation rate due to the reduced speed of the pump, the quantity of heat in the iron will flash this water into steam so that due to distention, sufficient water is lost so that the entire system breaks down. What is our figure What is this? The underhood openings of 226 sq.in. will not be adequate. Have assumed that 3.3" depth core you have is as efficient as those built over here and from this curve have taken the air temperature rise figures and the volume of air. This figure together with the increase in volume due to the temperature rise across the core discloses that of the air available due to the motion of the car through the air, 48% of the available air is used, therefore, 48% of the frontal area of the core gives us a figure of 277 sq.in. of outlet area required as a minimum. Under the circumstances feel that your 426 sq.in. figure will be perfectly satisfactory. HEAT TRANSFER PRODUCTS AVIATION AUTOMOTIVE MARINE INDUSTRIAL RADIATORS · SHUTTERS · OIL TEMPERATURE REGULATORS · CAR HEATERS · THERMOSTATS · HEAT EXCHANGERS | ||