Viewing page 48 of 74

This transcription has been completed. Contact us with corrections.

-2-

of fundamental research conducted by the N.A.C.A. for many years. Advances made in the various fields have rapidly been reflected in the availability of better aircraft to the military and to the commercial air lines.

In the field of aerodynamic efficiency, for example, we can already record marked improvements in the development of low frag wings, of highlift devices, of improvement in propeller efficiency, and reduction of frag of the propulsive system. Further marked progress is already in view, and we may anticipate appreciable drag reductions for the wind and other parts of airplanes, lower drag cowlings for radial engines, improvements in efficiency through the use of internal engines, and more efficient propellers; all of which will go toward permitting the air line operator to replace a good portion of the gas load he must now carry with pay load. Incidental to this direct gain, the commercial transport airplane will also be able to travel faster and get more miles per gallon of fuel, reducing not only direct flight expenses but the expenses incidental to procurement and maintenance of the power plant.

In the field of structural integrity, the N.A.C.A. V-G recorders have contributed marked progress. Through the cooperation of the air lines in carrying these instruments in their flight operations, this research has given a statistical picture of the actual loads encountered by aircraft in flight which is of the utmost importance in the design of new large aircraft. Only with such information has it been possible to insure the structural integrity of a design and yet achieve the minimum of weigh and maximum of useful load. We may indeed congratulate ourselves on the excellent record of American transport aircraft as to their structural integrity and may well recognize that this record is based upon the application of airworthiness requirements developed through a sound scientific understanding of the loads to be encountered. Here too progress is to static, and the new N.A.C.A. gust tunnel at Langley Field is even now providing a basis for further refinements in the structural design of modern aircraft as related to the operating conditions they will encounter.

In the field of stability and control, the trend toward greater performance has continued to raise broad problems and during recent years a sound basis for the design of stable and controllable airplanes has been reached. Design methods have been made available in N.A.C.A. reports by which it has been assured that airplanes exhibit no gross instability or lack of control. Complete safety in flight, in so far as it is affects by the flying and handling characteristics of the airplane, has been attained. Here too research will continue to provide both broad and detailed improvements. With the new N.A.C.A. free-flight wind tunnel about to be placed in operation at Langley Field, it appears that a still better understanding of the relation between design factors and the final flying qualities of the airplane is in view. With the excellent safety record already established by the air lines under the American flag, it appears that even the few accidents traceable to flying qualities of the airplane may be eliminated in the near future.

In engines, as well as in airplane design, progress is constantly being made which will quickly operate for the improvement of transport aircraft. Many developments can be named, for example, improved cylinder