The ECONOMICS of POST-WAR CARRIAGE OF AIR CARGO 430158
LOWER costs on transport of higher classes of surface freight and express through better planned equipment will be of paramount importance in the post-war period, Mr. Sheehan declares. Airline replies from a recent survey, he says, show that 83% of the carriers favor cargo-carrying facilities in passenger planes for the post-war period, particularly for transcontinental and transoceanic operation, and even for feeder line service. For the lowest ton-mile costs, however, exclusive cargo planes are the ultimate goal. Larger combination planes, for the time being, will doubtless prove most practical during the initial stages of domestic cargo development.
Curves and charts showing the effect on ton-mile costs of different size planes with varying power units emphasize the principle that the largest airplane operates at the lowest ton-mile cost. But he stresses the point that speed is another governing factor in cargo haulage. Where speed is of major importance, twin-engined planes are most efficient. A governing factor on four-engine ships is take-off weight, which must be limited, so that CAR landing weight is not exceeded for short ranges.
The twin-engine plane has its best advantage under 250 miles, and beyond that figure four-engined plane efficiency improves. At ranges of 500 miles, he shows that, on a four-engine plane, a 20-mile difference in speed affected operating costs about 5¢ a ton-mile, and on a two-engine plane, the same speed differential caused a cost differential of about 2¢ per ton-mile. Twin-engine planes are the most economical if size of payload does not exceed capacity of largest twin powerplants available.