At that time, the Hamilton-Standard duralumin blades were clamped into the sockets of steel hubs in such a way that when an airplane stood on the ground, the blades might be adjusted to whatever setting was desired. However, once set, the blades were not adjustable in the air. This gave the airplane a handicap such as a motor car would have if deprived of its gearshift. The propeller shown in Frank’s drawing, however, had a mechanism for adjusting the propeller blade setting in the air. The pilot might use one setting, corresponding to low gear, when taking off, and another corresponding to high, for cruising. Frank visualized his “controllable pitch propeller” as the “gearshift of the air.” The idea of such a propeller was not new. Many people had tried the device and found it sound in conception; the problem was that no one had been able to build one of the things strong enough to stand up under the extremely high centrifugal and vibratory stresses found in propeller blades. The novelty of Frank’s design lay in its simple hydraulic control mechanism, in which oil pressure on a piston rotated the blades and locked them in either of two positions, the best setting for cruising or for take-off. Judged by the old engineering adage, “to be good it must look good,” Frank’s propeller looked to me like the answer to a maiden’s prayer. Now Frank Caldwell was no overenthusiastic salesman. The best he would say for his brain child was to express the quiet hope that it might amount to something some day—provided we could make it hang together. But to me there was no use fooling around; here was just the kind of gadget we needed to pull us out of the hole. I gave orders to shoot the works and rush the development of the “gearshift of the air.” Fifteen years later, after we had become more conscious of the need for corporate social security and after we had got ourselves all bound up in our own red tape, I doubt if United Aircraft would ever have undertaken such a project. For the problem was not so simple as I have so far stated it. The new propeller must of necessity prove more costly than the old type, and there was no proof that the increase in performance would justify the increased costs. This question did not lend itself to precise calculation, nor could we solve it by trying the propeller on an existing airplane. In order to realize the advantages of the new type we must build a new airplane designed to exploit it, and in those days people just didn’t haul off and build airplanes to sell other people’s propellers.