1.   Because the engine is air cooled, there is no need for a radiator.

2.   After a few more stops, which I gathered was sufficient cooling time, she lifted the pocketbook and sat down.

3.   The blades are air-cooled, but the guts of the engine are oil cooled, like your car.

4.   This factor takes into account the humidity on the ground and how fast the temperature of the air cools as it is measured higher and higher above the terrain.