I learned that a pilot had been up there and had gone over the whole stress analysis with them and had recommended only one little change in the ship, which had been made. I learned that he had expressed willingness to dive the ship after that, but that he had been unable to because another job he had contracted to do some time previously was coming up at the same time this one was. I was glad to hear this man had gone over the ship. He was not only one of the most, if not the most, competent test pilots in the country, but also a very good engineer, which I was not.
I crawled into the cockpit. There were more gadgets in it. Something for everything except putting wings back on in the air. The racket had changed, I decided. In the old days, dive demonstrating hadn’t been so accurate a thing. You took a ship up and did a good dive with it and came down and everybody was happy. But now, as I could see, they had developed a lot of recording as well as indicating instruments. You used to be able to get away with something. You couldn’t get away with anything now. They could take a look at all those trick instruments after you had come down and tell just what you had done. They could tell accurately and didn’t have to take your word for it.
There was one instrument there, for instance, that the pilot couldn’t see. It was called a vee-gee recorder. It made a pattern on a smoked glass of about the size of one of those paper packets of matches. This pattern told them, after the pilot had come down, just how fast he had dived, what kind of a dive he had made, and what kind of a pull-out he had done.
There was another instrument there that I had never seen before. It looked something like a speedometer and was called an accelerometer. I was soon to find out what that was for! Oh, they told me what it was for then. They explained everything in the cockpit to me, and I sat there and familiarized myself with it as best I could on the ground before taking the ship out. But I wasn’t really to find out what that accelerometer was for until I used it. And did I find out then!
We rolled the ship out that afternoon, after last-minute adjustments had been made on it—an airplane is like a woman that way: it always has to have last-minute adjustments—and I made a familiarization flight in it. I just took it off and flew it around at first. Then I began feeling it out. I rocked it and horsed it and yanked it and pulled it and watched. I watched the wires, the wings, the tail. Any unusual flexing? Abnormal vibration? Any flutter? I brought the ship down and had it inspected that night.
The next day I did the same thing. But I went a little bit further this time. I built up some speed. I did shallow dives. I listened and felt and watched. I did steeper dives. Anything unusual?
This went on for several days. Some minor changes and adjustments were made. Finally I said I was ready to start the official demonstrations, and the official naval observers were called out to watch.
I did five speed dives first. These were to demonstrate that the ship would dive to terminal velocity. Contrary to popular opinion, a falling object will not go faster and faster and faster and faster. It will go faster and faster only up to a certain point. That point is reached when the object creates by its own passage through the air enough air resistance to that passage to equal in pounds the weight of the object. When that point is reached, the object will not fall any faster, no matter how much longer it falls. It is said to be at terminal velocity. A diving airplane is only a falling object, but it is a highly streamlined one, and therefore capable of a very high terminal velocity. A man falling through the air cannot attain a speed greater than about a hundred and twenty miles an hour. But the terminal velocity of an airplane is a lot more than that.
I led up to it carefully. I went to fifteen thousand feet to start the first dive. The ship dove smooth and steady. I pulled out at three hundred miles an hour and climbed back up to do the next dive. I dove to three hundred and twenty miles an hour this time. Everything was fine. Everything was fine as far as I could tell, but when I had eased out of the dive I brought the ship down for inspection before I did the next two dives.
I did the next two dives to three hundred and forty miles an hour and three hundred and sixty. I lost seven thousand feet in the last one. It had me casting the old fish eye around to see if everything was holding before I got through it. Everything held, but I brought the ship down for inspection again before the final speed dive.