Chapter 17 The third part of joining the army-1

The third story of joining the army When the Second World War broke out in Europe, and the United States had not officially declared its entry into the war, people began to talk about being ready for war and being a patriot.Newspapers widely reported that many businessmen volunteered to receive military training in places like Plattsburg and New York. I began to think that I should also contribute something.By this time, a friend of mine from my MIT fraternity, Mel, had joined the Army's signal team. After college, Mel took me to meet the colonel in the Signal Corps office in New York. "Colonel, I want to do something for my country. I'm a technical thinker, and maybe there's something I can do to help," I said.

"Very well, but you go to the barracks at Pressburg for basic training before we can use you," said the colonel. "Is there no other more direct way for me to come in handy?" "No. That's how the army stipulates, so let's do things according to the rules." Stepping outside, I sat in the park thinking about it.I thought and thought and thought maybe I should join the army the way they do.But fortunately, I thought about it a little more, and finally decided: "Never mind him! I'm going to wait a little longer, maybe there will be some turning point, so that I can contribute more."

So I went to Princeton to study in graduate school, and in the spring I went to New York to apply for a summer job at Bell Labs.I love visiting Bell Labs. Shockley, who invented the semiconductor, showed me around.I remember that in one room, someone made many marks on the glass windows.Outside the window, workers could be seen building the Washington Bridge, while people at Bell Labs had been watching the progress of the project.When the engineers installed the main cable of the bridge, they traced the curve on the window according to the shape of the cable; and when the bridge was suspended on the cable one after another, and the curve gradually became a parabola, they recorded various subtle differences .This is exactly what I like to do.I just adore these guys and hope to work with them one day.

The people in the lab took me to a seafood restaurant for lunch.They were delighted when they found out that they could have oysters for lunch that day.Living by the sea, I don't even want to look at seafood; I can't even eat fish, let alone oysters. But then I thought, "I should be brave and eat an oyster." I ate it and it was horrible.But then I thought, "That's not enough to make me a man. You don't know how horrible it's going to feel until you eat your first oyster, because it's easy to eat without knowing!" Others kept talking about how good those oysters were, so I ate another one, and this time it was even more terrifying than the last.

This is probably my fourth or fifth visit to Bell Labs, right?But this time they accepted my application, and I couldn't be happier, because in those days, it was not easy to find a job with other scientists. On the other hand, there was a sudden storm on the Princeton campus.General Chulacher from the Army came up to us and shouted, "We must hire physicists! Physicists are so important to our army! We need three physicists!" You know, in those days, most people didn't know What a physicist is.For example, even Einstein is classified as a mathematician, and it is rare to hear that anyone needs to hire a physicist.I thought, "This is my chance to serve my country." I signed up to work for the military.

I asked Bell Labs if they could let me work for the army during the summer vacation. They said that Bell Labs also had many war-related projects, and I could join if I wanted.However, at that time I was spreading "patriotic fever", so I lost a great opportunity.In fact, the smarter choice was to stay at Bell Labs, but in those days, it was easy to get patriotic and overwhelmed. I was sent to the Frankfurt ammunition in Philadelphia to study a "dinosaur" - a mechanical computer used to direct the firing of artillery.When an enemy plane flies by, the gunner uses a telescope to lock it, and this mechanical computer relies on its gears, cams, etc. to predict the aircraft's course.The computer was cleverly designed and beautifully built.One important trick it employs is "non-circular gears"—that is, gears that aren't traditionally circular; but they mesh and work well.Since the radius of the gear changes constantly as it rotates, the rotation of one gear becomes a function of another gear.

However, at that time, this kind of machinery had gradually declined, and soon, electronic computers made their grand debut. As for the military, after saying so many good things about physicists, the first job they assigned me was to check the gears from the blueprints to see if they were made correctly!After doing this for a period of time, the guy in charge of this department gradually found that I know more than these, and can be useful in many things; therefore, he spent more and more time discussing problems with me. There was a mechanical engineer in Frankfurt who kept designing new things, but none of them succeeded.At one point, he designed a box full of gears, one of which was eight inches in diameter with six spokes sticking out—a big gear like an octopus.The guy was very excited: "Boss, what do you think of this? Is this design good?"

"Very good!" said our boss, "Now you just need to add a 'axle passer' to each spoke, so that the gears can turn!" It turns out that the axle designed by this man is just stuck between the two spokes ! The boss then told us that the shaft adapter was real; at first I thought he was joking.He said it was a German invention to prevent British minesweepers from sweeping away the mines they had laid on the seabed.These mines are fixed by cables and suspended at a certain depth on the seabed; with shaft guides, the cables of the German mines can pass the cables of the British minesweepers, just like through a turnstile.

Therefore, it is possible to install axle guides for all spokes.But our boss didn't really ask the mechanical engineer to do this, but to redesign the position of the shaft. Every once in a while, the Army would send a lieutenant to check on us. The boss said that since we were a civilian unit, the lieutenant was higher than any of us; so, "don't tell the lieutenant anything," he said, "if he thinks he knows what we're doing, he'll give orders, screw everything up." At the time, I was also designing something, but when the lieutenant came to look, I acted like I didn't know what I was doing, so he thought I was just following orders.

"What are you doing here, Mr. Feynman?" "Well, they told me to draw a set of straight lines along the various angles, and then measure the various distances from the center point according to this table, and put them..." "What the hell is this?" "I think it's a cam." In fact, I designed this thing from start to finish, and I acted like I did what other people said. The Lieutenant couldn't get anything out of anyone, so we went on living happily and peacefully, working on the mechanical computer without any interruptions. One day the lieutenant came up and asked us a very simple question: "What if the person responsible for observing and tracking the aircraft was not in the same position as the gunner?"

Everyone was taken aback, because when we designed this thing, we thought about polar coordinates-that is, when marking positions, we used angles and how far away from the center point.If we use ordinary X-Y coordinates, the lieutenant's problem is easily solved, and the computer only needs to add, subtract, and subtract.But when dealing with polar coordinates, it's a mess!So we tried desperately to keep the lieutenant from talking nonsense, telling us to do this and that; but in the end he said something very useful, reminding us of important points we had neglected in designing this machine!Later, we spent a lot of effort to solve this problem. Towards the end of the summer, they assigned me a real design job. At that time, the British invented the instrument used to track the position of the aircraft, which was "radar". up.Every 15 seconds, the radar will appear on the screen; the instrument I want to design is to draw a continuous curve according to these points.This is the first time I have designed such a machine, and I am somewhat timid. I ran to a colleague and said, "You're a mechanical engineer, I don't know anything about mechanical engineering, but I just got this job..." "It's okay," He said, "Come on, let me teach you. When designing these machines, you just have to remember two rules. First, how much friction is in each bearing ... and how much friction is in the meshing of the gears. From these, you can calculate how much force is needed to drive it. Second, if you know the gear ratio, say 2 to 1, and you're wondering if you should use 10 to 5, 24 to 12, or 48 to 24 , so how do you decide? You can open the "Boston Gear Catalog" and choose the gear listed in the center of the table with neither too many nor too few teeth. Gears with too many teeth are difficult to manufacture, and gears with too few teeth It’s easy to break, and the golden mean is right.” When it came time to actually design that machine, I thought it was a lot of fun—just pick the gears listed in the middle of the table, and use the two numbers he gave me, and I could be a mechanical engineer! The Army didn't want me to go back to Princeton after the summer vacation to continue my degree. They kept instilling patriotism in me, and said that if I wanted to stay, they could let me coordinate the plan alone and design another film called "Conductor" " machine.However, I think this plan is relatively simple, because in this design, the gunner is also sitting in the aircraft, flying at the same altitude as the enemy aircraft.The gunner inputs the flight altitude and the estimated distance to the enemy plane into the "Commander", and the "Commander" automatically aims the gun at the enemy plane and ignites the fuse. As program director, I had to go to another barracks frequently to check launch data; they had some preliminary data.And I noticed that there are very few launches recorded at the high altitudes where the planes often patrol.When I asked why, I found out that the gunner was not using a timing fuse, but a gunpowder strip fuse. The powder-bar fuses don't work at that altitude - they go off with a hiss in thin air. At first, I thought that it would be enough to correct for the air resistance at different heights; however, I later found that my task was to design a cannonball that exploded at the correct moment—in other words, when the fuse went out. machine! I thought that was too difficult, so I headed back to Princeton.