382 POLAR PROBLEMS 



An air-cooled engine can be so cowled in that after it is once started 

 it can be kept at any desired temperature regardless of the outside 

 conditions, and the number of cooling fins on the engine cylinders 

 can be regulated by the manufacturer for the work in hand. 



STARTING ENGINES IN LOW TEMPERATURES 



The starting of engines appears to many a bugaboo in Arctic 

 flying, but that need not be troublesome. Fireproof canvas hoods 

 can be made to cover the motor. A cylinder of this canvas can be 

 led down from the bottom of the hood to a pressure gasoline stove 

 (similar to a Primus stove, only larger) on the ground, and the engine 

 can be heated to any desired temperature (Fig. i). Then, with proper 

 priming and the use of a little ether (though ether is seldom necessary) , 

 the engine can be started instantly, even with a hand crank. 



This method of starting the engines in low temperatures has sever- 

 al advantages, besides being simple and effective. The pre-warming 

 of the engines expands the metal parts gradually, whereas when the 

 motor is started stone-cold there is a quick change in the temperature 

 of the metal parts from the low atmospheric surroundings to the high 

 'operating temperature. There is danger in this latter procedure from 

 the unduly rapid expansion of the engine parts. 



PROPER LUBRICATION 



The oil for the motors has to be carefully selected. The first in- 

 clination would be to use a very light oil on account of the low tem- 

 peratures. But the consumption of such oil would be great and would 

 cut down the cruising radius, and when the motor gets warm on a 

 long flight it lacks the necessary qualities to protect the engine's 

 working parts. Its advantages would be that it would enable the 

 motors to be turned over more easily and (in the low temperatures) 

 would fiow more readily from the cans. But these advantages dis- 

 appear when the oil and motors are pre-heated. 



Dashboard and other delicate instruments that require grease for 

 operation are likely to get sluggish from the cold, and it is necessary 

 to treat them with graphite instead of grease. It may also be ad- 

 visable to insulate rather heavily certain leads in the engine that may 

 not be protected sufficiently by the cowling from cold streams of air. 



SKIS AS LANDING GEAR 



There are no mechanical difficulties, then, in the airplane itself 

 that necessarily prevent its successful operation in the Arctic. Skis 



