WINGS FOR TRANSPORTATION — ^WRIGHT 579 



MODERN AIR-TRANSPORT PLANES 



These curves, then, show the trend. Let us now see some of the 

 most modern air-transport planes now operating or about to be 

 placed in service. To start off again at the point where we previously 

 stopped — the Douglas DC-3 airplane— let us note in plate 5, figure 1, 

 the interior of this ship as used by United Airlines between New 

 York and Chicago. The picture speaks for itself as to the provisions 

 which are made for passenger comfort. Plate 5, figure 2, shows the 

 interior of a DC-3 accommodating 21 passengers as used on most of 

 the air lines in this country and many abroad. 



In plate 6, figure 1, is a view of the Short Empire flying boat which 

 is a thoroughly modern piece of equipment used by Imperial Airways 

 and seen in this country on its trial trans-Atlantic flights and in the 

 New York-to-Bermuda service last year. 



Next we see in plate 6, figure 2, the Boeing 314 which has done such 

 yeoman service in Pan American trans-Atlantic operations. Another 

 view, of the interior of this ship, in plate 6, figure 3, gives an idea of 

 the spaciousness and comfort that the passengers enjoy when travel- 

 ing on these Clippers. 



The Lockheed 14 in plate 7, figure 1, although smaller in size than 

 the DC-3, provides a very excellent and comfortable service at the 

 high cruising speed of 220 miles an hour. 



Plate T, figure 2, shows the DC-5, about to be put into feeder-line 

 service in this country. It is noteworthy for the introduction of the 

 tricycle landing gear. 



In plate 7, figure 3, there is shown a very fine view of the Boeing 

 307 Stratoliner, several of which were recently ordered by TWA and 

 Pan American, to be placed in service this year. And in plate 8, fig- 

 ure 1, we have a DC-4, the largest of land air transports yet produced. 

 It is noteworthy, not only for its fine performance and load-carrying 

 ability but again for the introduction of the tricycle landing gear. 



THE FUTURE FOR PERFORMANCE 



And now to examine three more tables indicating the possibilities 

 of the future for speed and range. In table 2 are shown the factors 

 which made possible the 80 percent increase in cruising speeds which 

 occurred from 1929 to 1939. The preponderant effect of aerodynamic 

 cleanness shown in the first item is noteworthy, with the additional 

 substantial items of increased wing loading, decreased power load- 

 ing, flying at higher altitudes, and wing efficiency; following with 

 minor improvements in the last three items, induced drag, propeller 

 efficiency, and weight reductions brought about by structural weight 

 improvement. These features have brought the speed from 105 to 



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