400 POLAR PROBLEMS 



than air-cooled, but they are at a disadvantage because of additional 

 weight per H. P., possible failure of the cooling system, and expensive 

 maintenance. This disadvantage is no greater in the Polar Regions 

 than elsewhere. 



In order that the temperature of the engines may be controlled, 

 both air-cooled and water-cooled engines should be fitted with variable 

 cowling. In water-cooled engines a radiator mixture of 33 per cent 

 alcohol, 2 per cent glycerine, and the rest water has been found to be 

 satisfactory in temperatures between — 48° and 0° C. ; but in the writer's 

 experience it proved more satisfactory to use unadulterated water 

 and keep the engine, the oil, and the water in the radiator above the 

 freezing point at all times. If alcohol and glycerine are used in the 

 radiator, an extra tank of radiator mixture should be carried in order 

 to replace the loss by evaporation. This tank should be directly 

 connected to the radiator and accessible to the pilot or navigator in 

 order that an anti-leak solution may be injected with the mixture if 

 necessary. 



All temperature difficulties with power units are minimized by the 

 fact that it is possible to keep the engine always above the freezing 

 point. This can be done by covering the power unit with temporary 

 insulation, such as a tent or hood made of fireproof material (Fig. 2), 

 and keeping it warm by any one of several convenient methods. Two 

 ordinary hurricane lanterns slung beneath an engine (such as a Liberty 

 or a Wright Whirlwind) well housed in a canvas cover will keep the 

 engine warm even when the general temperature is extremely low. 

 More heat from an oil stove or other contrivance may be applied to 

 warm the engine thoroughly before starting. 



Hangars for an Airplane Expedition 



Little expense or preliminary preparation except depositing supplies 

 is necessary in order to accommodate the airplanes and personnel ofan 

 airplane expedition to the Arctic. 



Any hangars or fixed buildings constructed in high latitudes will 

 become more or less covered with snowdrift during the winter. The 

 drifts obstruct the exits and entrances, and it causes much trouble to 

 keep them free from snow. The difficulty of snowdrifts about hangars 

 may be overcome by putting the hangar beneath the ground and having 

 the roof level with the general surface. The snow then drifts past 

 without accumulation. The planes can be run in and out over a ramp, 

 as was done at the underground hangars during the World War. 

 Underground, or rather under-ice, hangars might easily and econom- 

 ically be constructed under the ice conditions prevailing in the Antarc- 

 tic, but greater difficulty would be met in constructing an underground 

 hangar in the frozen ground on the Arctic coast. If planes are to be 



