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).
Page 2 of a letter from Harrison Radiator Corporation discussing radiator core performance and airflow.
| Identifier | ExFiles\Box 149a\3\ scan0193 | |
| Date | 7th October 1936 | |
| HARRISON RADIATOR CORPORATION LOCKPORT, NEW YORK October 7, 1936 -2- difference at max. speed. From this, conclude that the radiator resistance is approximately right as we have found that we cannot improve the car performance very much by changing the type of core if the tests run with and without the bonnet do not result in a maximum improvement of more than about 6° F.{Mr Friese} Under the circumstances, believe the radiator resistance as previously stated to be approximately right. In connection with the airflow through the core at slow speeds from a fan performance point of view, we have found over here that the position of the first louver on the right hand side of the car from the driver's seat with the fan running anti-clockwise when also viewed from the driver's seat, is very critical indeed. We have had occasions where it has been necessary to move this first louver or door further back toward the rear of the engine so that air will not be sucked into the louvers instead of being used as the discharge point. With one particular car in production over here some years ago, found it necessary to put dummy louvers on this side, the first louver opening being a distance of 11" from the back face of the core. The method we use over here to determine if such a critical condition exists, is to apply a few lengths of silk thread approximately 10 to 12" long to the end of a wire and explore the airflow in this area with the engine running at a speed equivalent to approximately 20 MPH and, of course, if the ends of the streamers enter the louvers, this position should be moved to one more satisfactory. On page 2 of your letter referring to the weight of the core, am apologizing for not making myself more clear, in that the weight of the core is not essential and you will not find any difference between a light and a heavy core of the same design. We have found that the thickness of the strip does not affect the heat transfer rate and if this test has not already been conducted, believe it can be omitted in perfect safety. While we are discussing cores, regarding the suggestion which we offered regarding two 2-1/8 cores, suggested this as an alternative for getting up-to-date cores of our design from the latest production machines in England. You will not find that two 2-1/8" cores equal quite the total dissipation of the single 4" core at slow speeds particularly. The maximum difference is not in excess of 4%, but the single core is obviously the best bet to use. HEAT TRANSFER PRODUCTS AVIATION . AUTOMOTIVE . MARINE . INDUSTRIAL RADIATORS . SHUTTERS . OIL TEMPERATURE REGULATORS . CAR HEATERS . THERMOSTATS . HEAT EXCHANGERS | ||