To anyone who has been identified with the aviation industry for as long as three decades, and to anyone who is willing to admit our mistakes, it will seem at times as if our progress in heavier-than-air aviation had been less audacious than that of our European competitors, and that despite our initiative we were constantly held back by our consideration for regulations and for models which were already obsolete.
Right under our noses, today, are wrong trends, unrealized, and right trends, unappreciated, because we don't think things through. The turbojet engine, for example, could have been built and used thirty years ago. And why was it not? Because at that time we were thinking in terms of 100-mile-per-hour aircraft, and any designer would have known that the fuel consumption was prohibitive. None of us realized then that the jet engine immediately meant 600 miles per hour. And so we missed it.
Another thing that kept us from going ahead faster was the belief that engines and air frames are separate entities. A review of aircraft design clearly shows how much time and cost were consumed in trying to fit existing engines into air frames that were never designed for each other. The two are, after all, a unit, and—with the advent now of vertical flying—air-flow requirements around a wing from the jet engine gas generator source make the wing construction an intimate part of the power plant.
Some clear and not too pleasant lessons are to be learned from a reflective perusal of the more than half century in which we have developed our air travel. One is how often designers and constructors have failed to finish up what was started. As a result of discouraging initial troubles and "bugs"—often intensified by lack of foresight and interest on the part of the aircraft customers, military, industrial, and civilian—the continuity of effort required to achieve success petered out, and consequently highly desirable developments that had been started were abandoned, only to be revived years later,
Many a novel and significant idea or suggestion has lain on our doorstep for years, unappreciated. Let us look at a few examples:
In America, where flying was born, the biplane dominated our picture for almost twenty-five years, despite the obvious success of the monoplane in France and the fundamental correctness of its aerodynamics.
The Junkers low-wing, cantilever stressed-skin, all-metal monoplane, after its development in Germany in 1920, was brought over to this country and promptly ignored. It was not until William Stout developed the Ford planes many years later that we moved seriously into the stressed-skin metal structure. Fokker, during the early twenties, also chose the cantilever stressedskin, but used plywood covering (which could not take the weather).
In earlier years, landing gears started with skids, to which wheels were added; but the skids were left on, only to become the cause of many wrecks when they broke on hard landings. From the very beginning, wheels alone were, obviously, the correct solution. In Europe, Bleriot, and in America, Curtiss were unique in realizing this, and the practical three-wheel gear was constantly being demonstrated as successful and correct by the early Curtiss planes. But practically no one else saw this. Even Curtiss gave it up later.
It should have been obvious that retractable landing gears were desirable at the earliest date at which we reached a speed of 100 miles per hour, 1912. But not until the advent of the successful amphibian plane (which had to have its landing gear foldable) did we learn that retracting a landing gear and housing it were neither too complicated nor too heavy. Nevertheless, it was some six or eight years before retractable gears came into more general use.
On the early configurations in America, engines were to the side of, or behind, the aviator. The Wright design, translating twelve horsepower into effective enough thrust to fly eight hundred pounds, needed the two large geared-down propellers; in fact, this was one of the secrets of their success. But as more powerful engines came along, such as in the case of Curtiss' using his motorcycle engine, the gearing-down was not needed, but the engines were kept behind the pilot. It is curious that we should have done this in the United States, when in France the great early pioneers, Bleriot and others, from the start had tractor-type monoplanes, although Farman and Voisin also used pushers.
It was not until 1913 that America saw the Burgess tractor with Renault motor, the Glen Martin Model T, and the Curtiss N, which later became the ubiquitous JN-4 (the Curtiss Jenny). As far as the general industry is concerned, we waited four or five years before adopting the tractor-type airplane, which was to become practically universal as a land plane, even when later developed into multimotor models.
The advent of the fuselage with enclosed seating was stimulated, of course, by the use of the tractor engine. But it is remarkable to note that the obvious further streamlining and closing in of the fuselage lagged for a few years. Nieuport, in his revolutionary little monoplane of 1910, which swept the field in competitive performance, practically started this vogue. But the enclosure of the aviators themselves in a cabin was very slow in coming, arid it was not really until some ten or fifteen years later that the majority of the aviators, including the military, discovered that they need not have their heads out in the open air in order to fly and permitted their prejudices against closed cabins to give way to the comforts that were immediately evident.
Flaps and slots to slow down landing speeds or rather to permit higher cruising speeds and heavier loads without too great a landing penalty, were a long time coming—much too long.
Handley-Page and Lachmann in Europe and Orville Wright in this country were researching these high-lift aids in the twenties. In fact, it is not generally known that Orville Wright in 1923 patented the split flap. By 1926, Handley-Page slots had been applied to the British Moth plane with great success. The first such Moth was imported to this country by me and flown widely in the East. Still, many airplanes were being built, developed, and accepted with no thought of high-lift devices. Others worked on this addition to wing structures, notably Harlan Fowler. Then, in 1929, the Guggenheim Competition was held, specifically designed to advance airplanes that could land in smaller fields over obstacles without sacrifice of useful high speed.
The winner of that competition was the Curtiss Tanager, a very intelligent design that made full use of the then existing high-lift devices. Did all aircraft, the year following, adopt split flaps, or Fowler flaps, or Handley-Page slots that had been so successfully demonstrated? They did not. There was the usual opposition, criticism, and delay for several years more before this highly desirable development in aircraft wing structure came to its now universal fruition.
Even recently we have had a rather surprising example of delay in acceptance: the HelloCourier, developed in Boston by Koppen and Bollinger. A convincing demonstration of this STOL (steep take-off and landing) airplane, with its correct use of slots and flaps for higher lift, was witnessed more than seven years ago, and, despite the great need of our ground Army for a plane of this type, it is only recently that the Defense Department has become interested and ordered some.