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 sizes required on the 'Fury' aircraft, contrasting water and ethylene glycol coolants at 12,000 ft.
| Identifier | ExFiles\Box 54\4\ Scan080 | |
| Date | 13th March 1933 guessed | |
| COMPARISON IN SIZE OF RADIATOR REQUIRED ON THE 'FURY' AIRCRAFT AT THE FULL THROTTLE HEIGHT OF 12,000 FT. (a) Operating as at present with water just below the boiling point corresponding to the reduced pressure with the engine developing 480 BHP. at 2250 RPM. (b) Operating with undiluted Ethylene Glycol maintaining an outlet temperature of 120°C. with the engine developing 600 BHP. at 2600 RPM. Size of present radiator on the 'Fury' 2.2 sq.ft. frontal area. Size of radiator to suit condition (b) 2 sq.ft. This assumes the same air speed on the climb in both cases. With the increased power the climbing speed will most probably be higher resulting in a still less radiator area. Under the conditions (b) it is interesting to note that only on the tail end of the climb will the outlet temperature reach 120°C. When cruising at normal R.P.M. at 12,000 ft., the outlet temperature will fall to approx. 94°C., whilst on a full throttle burst at the same height the outlet temperatures are 104°C. These figures thus show that the greater part of the flying time will be at temperatures round about 100°C. and we might raise the maximum temperature at the end of the climb to bring the mean nearer 120°C. This will still further reduce the area of radiator required. When considering the properties of Ethylene Glycol it is interesting to note the following comparisons with water:- Ethylene Glycol at 120°C. Sp. {Mr Spinney} Heat .70 Sp. {Mr Spinney} Grav. 1.036 Water at 88°C. (i.e. boiling point at 12,000 ft) Sp. {Mr Spinney} Heat 1.0 Sp. {Mr Spinney} Grav. .965 Under these conditions of outlet temperature the heat flow to the jackets is about 6% less when using Glycol. Expressing the above results in another way the same size radiator conditions of air flow remaining the same will cool an engine developing 35% more BHP. with a maximum climbing outlet temperature of 120°C. | ||