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).
Letter from Harrison Radiator Corporation discussing vehicle cooling systems, critical air temperatures, and radiator design.
| Identifier | ExFiles\Box 149a\3\ scan0177 | |
| Date | 18th August 1936 | |
| HARRISON RADIATOR CORPORATION LOCKPORT, NEW YORK August 18, 1936 - 2 - The method you use for determining the critical air temperature is similar to that which we use over here, unfortunately you omitted to state under what test circumstances the critical temperature figures given were obtained. This is of interest in that it gives us an opportunity to definitely determine whether or not the cause of the cooling trouble is due to lack of core material or airflow. Assume that the Bentley and the 25 HP. cars which you refer as having critical air temperature of 48 and 53°C. are the figures obtained at maximum speed and we would say that the 53°C. figure is an exceptionally well cooled machine. As a matter of interest we have found that the fan at low speed assists in drawing air through the radiators and at some speed this condition is changed in that the fan assists very materially in pushing the air out from under the hood. We have found over here that we have been able to materially assist the high gasoline pump temperatures by fitting the gasoline line outside the frame channel. This results in a better cooling condition and assists materially in reducing the gasoline temperature. Answering your questions on page 2 specifically, under No. 1 "How do you define or measure the cooling of your cars?", am enclosing a copy of a paper which was presented before the Chicago section of the Society of Automotive Engineers last winter in which this question is answered. In No. 2 what we consider adequate cooling for a car, we have found that cars which at 20 MPH full load have a critical or breakdown air temperature between 100 and 110°F and at maximum speed, a critical or breakdown air temperature of 110 to 120°F do not result in service complaints. 47°C. Under No. 3 concerning the value of cowling in front of and behind the core, we have not run any tests of this description on the Cadillac but some years ago a series of tests were run at the Proving Grounds on a Buick car to which was fitted a telescopic or collapsible cowl in front of the radiator. Results disclosed that 60 MPH, the cowling which extended 5" from the face of the radiator core resulted in an increase in cooling equivalent to 1/2" in the depth of the radiator and with the cowling extended to 8" from the front face of the radiator, HEAT TRANSFER PRODUCTS AVIATION AUTOMOTIVE MARINE INDUSTRIAL. RADIATORS SHUTTERS OIL TEMPERATURE REGULATORS CAR HEATERS THERMOSTATS HEAT EXCHANGERS | ||