WINGS FOR TRANSPORTATION — WRIGHT 571 



ing, it also incorporated the Wright Cyclone engine with NACA cowl, 

 the wing flap with resultant permissible increase in wing loading, and 

 the controllable-pitch propeller. Cruising at 180 miles an hour with 

 a complement of 14 passengers, it provided a degree of excellence in 

 air transportation unequaled (if not indeed unapproached) by any 

 other piece of equipment. It is indeed fitting that the Guggenheim 

 Medal should be awarded to Donald Douglas this year in recognition of 

 his contributions to air transportation, starting as he did mainly with 

 the introduction of the DC-2. Plate 3, figure 2, is a view of this air- 

 plane in flight. 



Again to revert to flying boats, there is shown in plate 4, figure 1, 

 the Martin 130, by means of which the Pacific route of Pan American 

 Airways was opened up. Cruising at 130 miles an hour, this flying boat 

 possessed a very high ratio of useful load in proportion to gross weight. 



The next big step in equipment development was the Douglas DC-3, 

 the present standard of air-transport equipment of the air lines of 

 the world. Although developed directly from the DC-2, neverthe- 

 less, by virtue of greater span and larger fuselage, coupled with 

 slightly more power permitting a substantial increase in useful load, 

 it has made possible very great economy of operation. With a gross 

 weight of about 24,000 pounds and a payload of 5,000, it cruises at 

 181 miles an hour and can be operated at a direct operating cost of $65 

 an hour; 39 cents a mile; and 1.8 cents per 200-pound payload unit per 

 mile. This airplane is shown in plate 4, figure 2. 



TRENDS 



Having illustrated the advance in air-transport equipment to this 

 point, it is desirable now to show by a series of graphs the trends which 

 are indicated for various phases of our subject. 



GROWTH OF Am TRANSPORTATION 



First, let us consider the growth of air transportation as illustrated 

 in figure 1. The four sets of curves are self-explanatory in showing 

 a tendency to accelerate in growth during the past 2 or 3 years, and 

 particularly in 1939, as measured by growth in airways, passengers, 

 passenger-miles, and ton-miles of mail and express. One can only 

 reach the conclusion from these data that there will be a substantial 

 period of time before any falling off in tendency to increase may be 

 expected. 



ECONOMIC ASPECTS 



Now let us consider certain economic aspects of the situation in a 

 second group of graphs (fig. 2). Here, under figure 2 (A) is indi- 

 cated the saving involved by air travel as against rail when considering 



