AS speeds and operational altitudes of modern aircraft continue to increase, it is becoming more and more important that the total drag of the airplane be reduced while the rate of heat dissipation per unit frontal area of radiator be kept as high as possible.
The standard method of increasing the temperature difference between cooling medium and coolant has been to use ethylene glycol as a coolant, because its boiling point is much higher than that of water; however, in its pure state glycol has various disadvantages that are not present when a pressure water system is used.
This is a sealed system for making use of the physical characteristics of the increase in boiling temperature with pressure. When the radiator receives more heat from the engine than it is dissipating, a small quantity of steam is generated inside the cylinder jackets. The resulting increase in pressure will cause the temperature to rise until a balance is restored between heat rejection and radiator dissipation.
In discussing the results of his experiences with pressure cooling, Mr. Ellor has included design details of a header tank and a suitable thermostatic header tank relief valve.
