Oral-History:Chandos Rypinski

About Chandos Rypinski

Chandos Rypinski's early love of amateur radio and experimenting with radio equipment determined the rest of his pathbreaking career. A graduate of Cal Tech, Rypinski contributed a great deal to the U.S. military effort throughout World War II, especially with his work in radar. Rypinski learned and taught others to operate and maintain the 584 anti-aircraft radar, and prepared synchronized plotting boards to calculate enemy flight trajectories. These inventions helped achieve U.S. successes in the Iwo Jima and Okinawa military campaigns.

The interview describes Rypinski's early fascination with radio and some of his experiences in and opinions of the wartime theater of operations in the South Pacific. Rypinski discusses radar developments and working with Marine Corps organs such as the First Provisional Air Support Command.

About the Interview

Chandos Rypinski: An Interview conducted by Frederik Nebeker, IEEE History Center, July 16, 1991

Interview # 106 for the IEEE History Center, The Institute of Electrical and Electronics Engineers, Inc.

Copyright Statement

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It is recommended that this oral history be cited as follows:

Chandos Rypinski, an oral history conducted in 1991 by Frederik Nebeker, IEEE History Center, Hoboken, NJ, USA.

Interview

Interview: Chandos Rypinski

Interviewer: Frederik Nebeker

Place: IEEE Center for the History of Electrical Engineering, New Brunswick, NJ

Date: July 16, 1991

Childhood and Education

Nebeker:

This is an interview with Chandos Rypinski on the 16th of July, 1991 at the Center for the History of Electrical Engineering in New Brunswick, New Jersey. The interviewer is Rik Nebeker. Could we begin by talking about your background, what experience with radio and electronics you had, and what education you had?

Rypinski:

I became interested in radio very young, possibly at twelve years old. My father had been on the periphery of the radio business though he was a power engineer. I also had an uncle who had been in Kolster Radio.

Nebeker:

Where did you grow up?

Rypinski:

Until I was six years old, I lived in New York City. In 1930 we came to California. So I went through the Los Angeles school system. But very early I started building radios. I built a few before one worked. Very often they were one-tube sets with types like 99 and carrying around the batteries. Fortunately, the broadcast stations were nearby, so I was able to receive signals. At that time we wound the inductor around a toilet paper tube with a magnet wire from old Ford spark coils. The most vital piece of equipment you had to buy was the headphones. At that time headphones were very sensitive; otherwise a great deal of the radio equipment wouldn't have worked. It was many years before I progressed to handle enough power to drive a speaker. In the beginning, the parts I had available were leftovers from the family broadcast radio. But by the time I was fourteen or fifteen years old, I was able to build regenerative detectors and one stage of audio with tubes like 24A and 57.

Nebeker:

Did you work with your father on these devices?

Rypinski:

Not much. My main source of input information was either the ARRL Amateur Radio Handbook, which was the bible to me, or the RCA Tube Manual, which had application circuits in it for using the vacuum tubes. I tended to copy circuits that were given. I couldn't exactly copy them because I never had the same materials to work with, and I had no money to spend. So it occasionally took quite a bit of ingenuity to make an approximate copy. After a time I came to learn what worked and didn't work. So I'd say by the time I was in my second year in high school, I was building one-tube transmitters and two-tube transmitters with self-controlled oscillators and power amplifiers. The power amplifier for me at that time was a 45 or 47, which might manage a watt or two at forty meters, or later, twenty meters. My call was W6RDR when I finally got a license. I operated for a time without a license, but that got my code speed up. Within the first three days of getting my license, I talked to a station in Hawaii from Los Angeles, and that so thrilled me that I was fired up. This is all manual telegraphy, not voice.

Nebeker:

Yes. Was that in high school that you made devices?

Rypinski:

Yes. So by the time I was a senior in high school, I was building superheterodyne radios. They had a tendency to use regenerative IFs and regenerative RFs, which is a very difficult way to build a radio. But it gives the most performance per tube. It wasn't until some time later that I started building radios for stability and accuracy, rather than minimum parts. [Chuckling]

Nebeker:

So I take it you had decided that you were going into science or engineering?

Rypinski:

I had decided that I was going to be a technical person. When I took the entrance exams for Cal Tech, I knew radio and electronics pretty well, considering my physics instructor in high school excused me from the class. He didn't want me in there. I knew that subject pretty well, but at the time, I was thinking of going into chemical engineering, equally, and possibly physics. I later decided that I wasn't smart enough for physics after I encountered some people who were really good at that sort of thing. [Chuckling]

Nebeker:

How did it work in those days? Could you comment on the entrance exams at Cal Tech?

Rypinski:

Well, the first thing is that you really had to decide four years before you graduated high school because in order to take enough subjects to qualify for their entrance requirements, you were on a very strict schedule that was maximum math and science. I was always upset because I had burned off my electives on things Cal Tech required, and I never got to take any of the fun subjects like wood shop. I took German in high school, which was not a fun course. I took German in 1940 and the spring of 1941.

Nebeker:

So if you had the course requirements and if you passed the entrance exam you got in?

Rypinski:

First you had to have the scholastic requirements, and then that enabled you to apply to Cal Tech. You had to have pretty good grades. Then you took the entrance exam, and if you were still in the running, you were interviewed.

Nebeker:

I see.

Rypinski:

From my class in high school, Fairfax High School, there were three people accepted, of which I was the least accomplished. I was interviewed by Fred Lindvall, who was head of the EE department, and, as I later learned, a very distinguished man and a great gentleman.

Nebeker:

Now you must have done okay.

Rypinski:

Well, I did sufficiently well to get in, but I didn't make honors section, and I've never been a distinguished scholar. I'd say that at high school level I was hot in mathematics. But once I got amongst people who were good at math, I was no longer hot. [Chuckling]

Nebeker:

So you'd say that your experience at Cal Tech made it clear that you would not go on in physics?

Rypinski:

Yes. In the first year, my recollection is that there were no choices, and in the second year, you had to choose science or engineering. Then in the third and fourth, you got more specific. So the first year courses were physics, math, chemistry, and humanities. I was somewhat cocky my first semester, but that soon proved impractical and inappropriate. [Laughter]

Pearl Harbor and Cal Tech

Nebeker:

Was that in 1941 that you started at Cal Tech?

Rypinski:

I started Cal Tech in September '41. And on December 7th of '41, I had a ham radio schedule to talk to my father who was at Honolulu working for Bechtel, McCome, Parsons on underground fuel storage for Pearl Harbor. He was in facilities that were off of Pearl Harbor and slept through the raid. It was very interesting because a few years later I was on the exact same ground that he was on.

Nebeker:

Did you make contact with your father that day?

Rypinski:

No. I didn't know anything had happened. I showed up at this friend's ham station not far from Cal Tech on Hill Avenue, and he said, "I don't think we're going to get through. Let's twirl the knob and see what the band sounds like." It was somewhat quieter, but it didn't seem like there was any propagation difficulty. But of course we never heard one peep from Hawaii on the radio bands. Later in the day, of course, ham radio had been shut down.

Nebeker:

Why was that?

Rypinski:

Once a war starts, there is no ham radio.

Nebeker:

Oh. I didn't know that.

Rypinski:

All ham radio was shut down in 1939. I listened to the ham bands, and remember the disappearance of a Lithuanian station from the Russian Occupation. He was there one night, and he was not there the next.

Nebeker:

Could you receive Lithuania from Los Angeles?

Rypinski:

Oh, yes. I couldn't receive very many European signals because that's a difficult path, but I was well involved in long-distance and off-continent communications where you listen to very faint signals.

Nebeker:

I see. You say in your letter that you applied for voluntary induction.

Rypinski:

Yes. In October 1942 Cal Tech was pretty much operating normally. Then in the fall, all of the services showed up and made a presentation. The essence was that if you were a junior or more, you were going to be deferred to finish your education, possibly with some commitments to use that education. If you were a sophomore or less, you were going to be drafted. The services said, "However, if you don't want to be drafted, you're welcome to join our officer reserve program." So nearly everybody opted for one of the reserve programs: V12 for the Navy, I think it was. I opted for the Marine Corps Reserve program. So I took my physical, and everything was fine. I was about twenty pounds overweight, but the doctor noted "not obese." I wasn't fat. I was just big and round. But I was too short. In order to be a Marine Corps officer, I think you have to be 5' 6" or 5' 6-1/2". I was 5'/5-1/2" at that time. So I was rejected as an officer candidate for the Marine Corps. I was about eighteen years old. The programs for the others had closed, and I'd lost interest in the reserve officer programs. So I just decided to keep on going. In about March and April of '42, they started calling up all of these guys. By April, a class that had been 160 was down to something like twenty or forty. And I couldn't stand it anymore.

Nebeker:

What was your position? Did you have a deferment?

Rypinski:

I had applied for deferment, and I got it. So far as I could tell, it was going to go on because Cal Tech was very well thought of by the local citizenry. I can't explain it. All I can say is I was granted the deferment because I asked for it to go to school. So in May of '43 my grades weren't so good.

Nebeker:

That was the end of your sophomore year?

Marine Corps

Rypinski:

Near the end of my sophomore year. I was much distracted by everyone leaving. It was a turmoil situation, so I applied for voluntary induction. What happened was I just showed up at one of the recruiting offices in Pasadena and said I'd like to enlist in the Marine Corps. So he gave me some papers to fill out, and it soon appeared that I had this radio license and experience. He said, "Go home and wait 'til you hear from us." I heard from them about a week later, and they said, "We want you to take an examination." So at the appointed time, I took this examination, and it was mainly about radio theory and radio, and it was mostly stuff that with the combination of an engineering preparation and my ham experience, I did very well. My wife, who was then a librarian at Cal Tech, said that they had come around to investigate whether I had any way of knowing in advance what the exam was about. But I scored very well. It turned out that they offered me an enlistment in the Marine Corps where I would go through boot camp and be promoted to Staff Sergeant right out of boot camp. I just said, "Yes." I didn't make any decision. That was what they offered, that was what I took.

Nebeker:

You knew that you would then be working in electronics somewhere?

Rypinski:

Yes. They told me that I would be working in communication or something to do with my radio skill. So in May of '43 I reported, and I soon was in the boot camp at San Diego Marine Corps Base. I had no problem with the physical side of boot camp — far less problem than most people. I was in very good physical shape.

Nebeker:

Was that El Toro or the Marine base down there?

Rypinski:

The Marine Corps base was boot camp, right at the end of the runway next to what was then Consolidated Aviation. A few months before I came to boot camp, an airplane had gone off the runway and killed a bunch of recruits going into the Marine Corps depot. Tyrone Power had just passed through boot camp a few weeks before. A lot of stories about him were going around.

Nebeker:

So that was the summer of '43 that you went through boot camp?

Rypinski:

That was May, June, July '43. It soon became apparent that I knew a little more about reading and writing than most of the others, and no one knew that I was going to get the promotion until maybe about a week before the end of boot camp. So I had no problem getting along with people. I had a problem because my legs were short, and I couldn't walk quite as fast as some of them. [Chuckling] The way a Marine Corps platoon is organized, they put the tallest guys in the front and the shortest guys in back. So the platoon moves at the speed of these long-legged guys in the front. And some of them were in pretty good shape, too.

Nebeker:

That was the greatest challenge the Marine Corps offered you? [Laughter]

Rypinski:

Well, I had more coming. I got my stripes right out of boot camp, and I'd hardly had a chance to learn the culture of the Marine Corps when I was assigned to teach electricity and magnetism in a school at the Marine Corps Base, right out of boot camp. I had no problem with the courses or with the students particularly, even though most of them were just as young as I was. There was an occasional veteran back from Guadalcanal or Bougainville or something like that, but I was yet to encounter those guys. I was dissatisfied with the teaching in a school.

Nebeker:

Where was the school?

Rypinski:

At the Marine Corps Base.

Nebeker:

There in San Diego?

Rypinski:

Right in San Diego. But I had a fairly comfortable situation. I could drive home to Los Angeles on weekends, though that was challenging in the blackout: no headlights, no street lights. [Chuckling] I woke up once being passed by a Greyhound bus on the wrong side.

Radar School

Rypinski:

It came to pass that I was transferred to Camp Lejeune to go to radar school. I went across the country on the train, and showed up at Camp Lejeune, North Carolina. It's about in the middle between the northern and southern borders of North Carolina. Onslow Beach is a prominent feature of that terrain. I showed up at the brick barracks buildings, and I noticed in the back of one was a 584. I didn't know it was an SCR-584. I knew it was a prewar trailer with a parabola on top. [Chuckling] That immediately fascinated me. But that was all of I was to see of the 584 in Camp Lejeune. I was assigned to school. The school was SCR-270 radar at Camp Lejeune, and the most challenging thing about a 270 radar was starting the diesel generator in winter. The crew would be about ten or twelve able-bodied citizens, and the starter was a crank plus twelve citizens. [Laughter] These things were hard to start, but we did it.

Nebeker:

Now this was a long-distance radar?

Rypinski:

The 270 radar is an air-search radar about 106 or 112 MHz. The antenna is sometimes called a bedspring; it was about four full-wave dipoles wide and eight rows high on a trailer, arranged to rotate. You could easily see targets a hundred miles out, maybe further. You could see IFF where there was a transponder on the plane, and quite a bit further than that.

Nebeker:

And so your job there was to learn how to operate this?

Rypinski:

Operation was incidental. I was to learn to maintain.

Nebeker:

I see.

Rypinski:

The crew chief essentially had to be both. Now it wasn't apparent what I was going to be. I just went through the school like everyone else. They told me that I had the highest score in about the last thousand Marines who went through that school, at the end. What they wanted me to do was teach. I'd found occasionally the instructors made an error which I picked up. Not a lot of wisdom at that age. [Chuckling] But I understood the 270 radar. There was a lot of stuff in it, transmission line stuff, where there were no insulators, so the transmission line was set up with two stubs that would look like a short circuit to an electrician but in fact were resonant supports, and at the frequency at which the radar operated, were not short circuits. So this business of tuning transmission lines to turn a short circuit into an open circuit with a quarter wave of line was quite familiar to me. While other people were learning, I was just sitting there.

Platoon Sergeant in Rifle Company

Rypinski:

So I went through 270 radar school, and I'd made the decision that I didn't want to stay and be an instructor. The Marine Corps had made the decision that that was okay with them; they were going to ship me out. I was put in a replacement battalion where I learned to be a platoon sergeant in a rifle company, and we made landings, I remember, in February on Onslow Beach. But the "swabbies" wouldn't drive the boat far enough up on the beach, and you got out with your gear over your head, which for me was chin high in water. It was just between snowing and raining, which it did alternately. Since I was the platoon leader, we had a big dispute as to whether to walk back to the bivouac or run back to the bivouac, and I made the decision that we should run. There were dissenters. I made big decisions like that in the Marine Corps. [Chuckling]

Nebeker:

As far as you knew, you had turned down this position of teaching at that radio school.

Rypinski:

Yes. Well, I wouldn't know where I was going to be sent to teach. All I know is that I said that I wanted to go in the combat direction, not in the base direction.

Nebeker:

And it looked like you wouldn't be crew chief or in any way connected with the radar?

Rypinski:

I had no idea. I was going to be chief of something because I had staff sergeant's stripes. But to the Marine Corps at that time, that was sort of an awkwardness that I had those. Because they like people to go through the ranks. I had some difficulty. I was in charge of a room in a barracks that had about a hundred people in it, about ten or twelve of whom had battle experience and had come back from the First Marine Division at Guadalcanal and Bougainville. A couple of these guys went out of their way to give me a hard time, and I was somewhat tested. That's another story. [Chuckling] But in any case, I went through this replacement battalion. We got on a ship, sailed from Norfolk through the Panama Canal, and I ended up at Pearl Harbor Navy Yard in Oahu.

SCR-584 Crew Chief

Nebeker:

What was your assignment?

Rypinski:

We just sat around a while. And then we got word. There were a bunch of us who were all radar men with more or less parallel experience, but we were a small part of a battalion; we were just a dozen or something like that. We got word we were all going to go through radar school, and that turned out to be 584 radar school in Pearl Harbor, and it was taught by someone who was six months ahead of us. My recollection is that it was adequately taught. He explained the blocks and how the pieces worked and what they were for. We all got some exposure to one set that they had.

Nebeker:

How was it, moving from the 270 to the 584? How did that seem to you?

Rypinski:

It never occurred to me that I was moving. My knowledge wasn't based on the 270. My knowledge was based on how radio and RF worked. Now of course the 584 is an entirely different technology. To me it was fascinating and a revelation. I had never up to that moment seen or heard of a magnetron or klystron. They used a klystron for the local oscillator on the receiver, and a magnetron for the transmitter. But the three tubes that pulsed the magnetron were 6C21s, which is a variant of the EIMAC 450TL. And I remembered the 450TL very well. It's a transmitting tube with a tantalum plate, 450 W disipation. When it's dissipating 450 W, the plate is cherry red and can get white hot. You get a dramatic feeling of power from these things. When the transformers are loaded, it's like the Clydesdale horses pulling on the harness. [Chuckling] The peak power in the 584 is 250 megawatts, which is a lot of juice. However, it's only there for one microsecond.

Nebeker:

Was there much transfer of knowledge that you learned about the 270 to the 584?

Rypinski:

I never thought of it. I simply didn't approach it that way.

Nebeker:

Had the people going through the 584 school all gone through the 270 school?

Rypinski:

I don't know that. Certainly some had. Each of these groups has a few people from the last environment, but it's not specifically the same group of people. So there were some SCR-268 people being upgraded. I think they put their best people through that radar school.

Nebeker:

Did you feel privileged to be going through that school? Were you glad about it?

Rypinski:

I wouldn't have used the word "privileged." But I was extremely pleased and happy. I thought this was great, and I came later to love that radar. I could see immediately that it was interesting because it had servos and fine automatic tracking mechanisms in the positioning of the antenna. So I was very pleased about that assignment, but I still didn't know what was going to happen next.

Nebeker:

I was just trying to figure out when this was. You say in your letter that you completed the 270 school in about January of '44.

Rypinski:

Yes, I'd say that this was spring or summer of '44. Late spring maybe before I finished the 584. I think it was about six or eight weeks between when I arrived at Oahu and when I was transferred to the anti-aircraft battalion.

Nebeker:

Again the idea was that those of you going through this school would learn how to maintain the device?

Rypinski:

Yes. And you had to be able to operate it in order to maintain it. I could operate, as I did later, a 584 all by myself. I used to go out at night and do that. In the crew compartment there are three positions: one is the search position, one is the tracking position, and then in the back is the IFF operator. Forgetting IFF, I could take one chair and roll back and forth between search and track positions and operate the entire radar from beginning to end by myself fairly early.

Nebeker:

Was it usual that the people that went through that school then were crew chiefs on the 584?

Rypinski:

There were other crew chiefs. They went through that school without necessarily being crew chiefs because they were all ranks. Maybe corporals didn't.

Nebeker:

But they'd all get assigned to a 584?

Rypinski:

Yes.

Nebeker:

In some capacity.

Rypinski:

So the transfer was essentially to anti-aircraft battalion gun batteries. On Kauai at that time there were four Marine anti-aircraft battalions that had camped between Kapaa and Lihue, south of the Wailua River. Each battalion had four batteries of 90-mm guns, and each battery had one 584 radar. So there were a total of sixteen 584s and operating crews in that Marine camp. I was in the Eighth Anti-Aircraft Battalion, which had been the Eighth Defense Battalion before. The battalion had come back from somewhere in the Gilbert and Wallace Islands. Most of the people in it had been transferred out from malaria or mu-mu (elephantitis). Even though the structure of the battalion was in place all of the time, it turned over 100 percent of the personnel before that unit went into action again. Pretty soon these battalions were formed up, and we started learning how to fire the guns and use the radar.

Nebeker:

Were you a crew chief?

Rypinski:

I was a crew chief, and I had a crew. One or two of the people who worked for me in that crew had gone to this school and others hadn't.

Nebeker:

A crew chief means chief of the 584?

Rypinski:

Yes.

Nebeker:

Not of the battery?

Rypinski:

No. The battery has two officers, a commander and a lieutenant. The battery commander was a captain, and then a first lieutenant. There was a battery sergeant who'd be a platoon or gunnery sergeant probably. There might be a sergeant in charge of each gun and a gun crew.

Target Finding

Rypinski:

Then there is the gun director, and the gun director is a major piece of hardware. In our case, we had the M7 mechanical director. It was three officers because there was an officer just for the gun director and the aiming problem. The input came from two telescopes and two trackers: one tracked azimuth, the other in elevation. Their job was to turn a crank so that the target stayed in the cross hairs of the telescopes that they were looking through.

Then there was a third tracker on another piece of equipment which was called a height-finder, and that resembled a pair of binoculars with about eight feet between the lenses and a focus adjustment. From that triangulation, you could get slant range, and then also the director knew at what angle it was pointed upward, enabling calculation of the horizontal range. It was a one-piece instrument, actually, and they depended on it almost exclusively for range to the target. That was the optical firing setup. So when the radar was put in, the first thing was that the radar data was substituted for the height-finder data because it was more accurate than the optical setup. Then the means were there to substitute for the telescope inputs. In fact, we went back and forth. So in the beginning the mode of operation was very often that the radar would find the target before anyone could see it. We would put out bugs, bugs being an indication on the director of the angles elevation, azimuth and range to the target. Then the director crew would match our bugs. Then they'd look through the scope and see the target.

Nebeker:

I see.

Rypinski:

In the beginning we just did a target-finding operation because they had more confidence in firing at things that they could see. That was later refined to where we had searchlights. So the system was that the radar furnished bugs for the searchlights, the searchlights came on and illuminated, and the trackers on the director could see the target through the telescopes, and then they were in a position to fire.

Nebeker:

Was it possible to use the tracking directly from the 584?

Rypinski:

Yes, and we later did.

Nebeker:

Was there resistance to that change?

Rypinski:

There was resistance, but it was weak. It just took a while to build confidence in the radar. After people saw how good the radar data was, that resistance went away. Where it made people unhappy was where they still had 268 radars for the searchlights, and the 268s couldn't begin to approach the 584 for accuracy of information, and the searchlight guys were sore because they couldn't do their job nearly as well without the 584 radar.

Nebeker:

How did that actually work, the gun direction with the 584?

Rypinski:

The math problem, which only a few people in the gun battery understood, is that you're trying to predict the future position of the target based on current or past information. The M7 gun director was a linear extrapolation. That means that it takes the best straight line that it can draw from the last few minutes or few seconds of flight and extends a straight line. The shell that's fired has a fuse on it, and the fuse determines how many seconds after it's fired that it explodes. Generally it has to explode to bring the airplane down, because it won't be accurate enough to pass through the airplane. So fuse-cutting is a very tricky business. In the 90-mm guns, the fuse was cut by a loader in a special fitting on the gun, and the shell handed to someone who pushed it in the gun. So in between when the fuse was cut and when the shell is fired, there's a few seconds. This interval was called "fuse dead time", and it is the aiming calculation. But the length of the fuse dead time depends a lot on whether the guy who's loading the gun is fresh or tired. So if you only fire two rounds, which we did in practice, he's almost always fresh. But in real firing where one gun may fire ten or twelve rounds (and these are big and heavy projectiles, nearly four inches in diameter), they weren't always consistent. One of the errors in anti-aircraft fire is the fuse cutting. We did most of our practicing at 10,000 feet, and it would take about twenty to thirty seconds for the shell to get up to the target. So the fuse cut is this twenty or thirty second interval. The projectile travels a fairly long distance in one second.

The outputs of the director were the pointing angles of the gun and the fuse cut. And the inputs were the present position of the aircraft expressed as azimuth, elevation, and range. Those can be furnished either from the radar or from optics. It came to pass that the way the director is set up is that it has these dials on it. There's one bug for the present position of the director, and another bug for the radar, and I think there was a third one on there, and I don't remember which it is. But the operator of the radar can turn the crank to do any kind of matching between the bugs. So the normal mode for automatic fire is the tracker simply matches the radar bug, and there's a certain smoothing possible. Or roughing because he may not track smoothly. He can overshoot. Of course if they don't track smoothly, they lose their job. [Chuckling]

Nebeker:

What was done later on was that the optical tracking was dropped, and the M7 was used with the radar.

Rypinski:

Yes. Well, they usually looked through the telescope to see what they were tracking, but they wouldn't always see anything, either because of clouds, obscurity of the target (i.e., a plane far away may look pretty obscure, it may be very hard to see, it may match the sky), or because it's nighttime. Most of our practice was in daylight. Although we did fire once in a while with searchlights at night. Now the target was a sleeve that was towed by an airplane, a B-26. The pilots who towed the sleeve let out about two miles of cable between them and the sleeve, and some of us took offense at their conservatism. There's a safety officer whose duty was to be sure that the gun was pointed behind the plane before they fired, and with a two-mile head start, that was pretty much always the case. This sleeve was a nylon tube. Possibly it was three feet in diameter. I'm not sure I ever was close to one. They were perhaps ten feet long. Inside of it was a tetrahedral reflector made up of corners formed by three perpendicular planes, which is a radar target that returns signals in the direction from which they came. So we got a good return in the radar from the sleeve. But we could also get a return from the cable. This is what made the pilots apprehensive because it was possible for the radar to get off of the reflector in the sleeve and start tracking the cable and just sort of slither back to the airplane. Some of the people involved didn't like that to happen. [Chuckling] So far, success was generally described as shooting down the sleeve, and everyone felt good if they saw the sleeve come unhooked from the airplane and flutter to the ground.

Nebeker:

Did that often happen?

Rypinski:

When I was firing, yes. But I knew, and a few people knew, that that simply meant that a piece of the shell had gone through the cable, not necessarily through the sleeve. Now if you cut the sleeve in half, that would have been good, but no one ever did that. [Chuckling]

Nebeker:

So the judgment of how accurate the shot was visual?

Rypinski:

Yes. The working arrangement was that they used this optical stuff to see the puff of the shell exploding relative to the sleeve. So there was very often optical scoring. But regardless of the optical scoring, if the sleeve was cut off, it was considered a good shot.

Success and Reliability of 584

Nebeker:

Right. You say that you had great success. How about the other batteries?

Rypinski:

I don't really know, but because of subsequent events, I know that we were considered the best battery of the lot.

Nebeker:

I take it that there was a good deal of individual skill required in adjusting and operating the 584.

Rypinski:

Individual skill was required to get it to operate well. But to say that that skill resided in any single individual is a mistake. Any good person could probably bring it up to its capabilities. I thought that the other crew chiefs that were working with me for the most part were all quite good. I'd say that the finger of difference between us was one part luck and one part theater. [Chuckling] So far as actually doing good radar-directed gunfire, there wasn't really very much difference between the batteries. There was considerable perceived difference that we had a very good battery. First of all, we shot the sleeves down, and that started it. We were the first one to bring a sleeve down with just two rounds. They made a decision later on to have a show for higher brass. They picked our battery to do it, and we did it again: two rounds and the sleeve came down. Now that doesn't mean that we were better, really, but it meant we were sufficient. Basically what you would hope for is that everyone is adequate.

Nebeker:

<flashmp3>106 - rypinski - clip 1.mp3</flashmp3>

But how was the 584 to operate? Was it generally reliable?

Rypinski:

I loved that machine. It was beautiful to operate. We did have troubles. We had a trailer of spare parts with us, and basically you could fix anything by replacing a gross part like a chassis. But I considered it a duty to track everything down to the part. If I had the part, I'd replace the part and not the chassis. So I didn't allow my supply of chassis to go down. Though I remember once that we had one chassis which puzzled me and I could not pin it down. I finally narrowed it to the properties of one transformer on that chassis, and it was not replaceable from our stock. I eventually had to give up that chassis. While we were there, we did something that caused a lot of trouble. There was something called moisture-and-fungus-proofing compound. As they were built, the chassis were bare naked. There was a field operation to spray them all with moisture-and-fungus-proofing compound, and that meant putting tape over certain critical points that weren't supposed to have this varnish sprayed on them, and handling them quite a bit. That created quite a bit of trouble that wasn't there before. Debugging that and finding the exact cause was, as I recall, sporting. But eventually everything was fungus-proofed.

Nebeker:

Was that important to have them fungus-proofed?

Rypinski:

We never found out whether it was important. We just did it. Hawaii is a fairly nice atmosphere. It's somewhat warm and humid and everything grows, and I suppose fungus would, too. But I think there was air-conditioning in the vans. I hadn't thought of that point. I don't know. There was certainly ventilation, and there was internally generated heat when it was used every day. For us there was no particular obvious benefit. But now that I look back at it, the span of time that I was watching was only nine months or so, though it seemed like forever at the time. [Chuckling]

Nebeker:

You had an adequate supply of spare parts?

Rypinski:

We had a glorious supply of spare parts. It was a special component trailer. It turned out that very few of the parts were actually used, and a small number of parts were almost consumables. The mixer diode on the receiver front end was virtually a consumable. Very often inexperienced crews would not change it often enough because the only symptom was the sensitivity of the radar and the range at which it would pick up targets would go down. At the close distances where we were firing, there was no visible difference with a good or a bad diode in it. So you had to be very sensitive to the performance of the radar to realize that you were losing something. I'd say a proportion of the crews didn't have anyone who reacted to that probability. Of course it seemed at the time like it wasn't a good idea to use up your spare parts while you were in training. I didn't have that viewpoint. I first kept it working well, and the spare parts I didn't think about particularly.

Nebeker:

Did it seem to you when you got out as a crew chief that your training had been adequate for the 584?

Rypinski:

I never had for one instant a reflection or a doubt about the training. My view was if I couldn't fix it, I was at fault. Now then, remember that my duties weren't for me to fix everything, and I only worked on the things that nobody else could fix. So if the crew could fix it, they always had first crack. But there were two kinds of fixing: one is to minimize the amount of time the radar is out of service or unavailable. The other is, "Well, you've got quiet time now; let's look into this further." We fortunately had a lot of quiet time when we could look into things.

Nebeker:

Did you have much contact with the other 584 crews?

Rypinski:

Four of them. All of the ones in the same battery. We were a family, I'd say. We played poker together in the evening. It turned out that on the whole the people in radar had better education and more intellectual interests than did the others. I'd say we were less prone to get drunk.

Nebeker:

Was it your impression that other 584s also functioned well?

Rypinski:

I think our whole battalion was effective, and I don't know about the rest. I assume it, but we didn't have enough contact.

I want to tell a little story now. We had a thirty KVA generator that went with the radar, and it was a three-phase generator. We loaned it out one night to a searchlight battalion whose generator had had some trouble, and they needed it, and we didn't. So we came back, and we had to go somewhere and set up, and the normal way you set up the 584 is you start plugging things together. In travel position, the antenna housing with that parabola on it sits on the floor of the crew compartment. When you're ready to set up, you turn on some motors, and the pedestal and the part of the roof that supports the pedestal, which has been down in the crew compartment, rises up and into the roof. When you're done, the antenna sticks out the top, and the space where it used to be is where the crew works.

So we're out there setting up, and I'm standing, giving the instructions to do the things in the proper sequence: turn on the generator, open up the roof hatch. Someone stands by the switch. So I gave the word to raise the pedestal, and I'm watching the radar, and nothing happens for a moment. And I'm thinking, How can this be? The power's on, but the antenna's not coming up. In about five or ten seconds at the four corners of this compartment, the roof started ripping apart, and the lead screws that usually raise the antenna up started coming out of the roof. What had happened was that they'd reversed the phase rotation on the three-phase power connection of the generator. And instead of the antenna rising up, the antenna tried to go down, which it couldn't. So the lead screws came up and out the roof. I understood what was happening very quickly. What I've described in thirty or forty seconds went by in about five or ten seconds. I hollered to shut off the motors, and went over to survey the damage. As I'm coming over to look at this thing, I'm imagining: This radar cost $250,000, an astronomical sum, and I just ruined it, and it's going to come out of my pay. [Laughter] I was really frightened by that. But we started looking at things, and taking things apart. The first thing was dismantling what we had to, to see what was broken and how much we could put back. As it turned out, we were able to repair it completely right there and put everything back so that it was serviceable. But I didn't know that until a day later. Meanwhile, the whole crew and I worked on that continuously, on both analysis and reaction. But we were able to fix that. None of us ever made the mistake again of not checking the generator phase rotation before use after it has been away. You know, you come to take these generators for granted. You use them every day. You don't expect the phase rotation to be reversed overnight.

Aircraft Tracking

Nebeker:

<flashmp3>106 - rypinski - clip 2.mp3</flashmp3>

Maybe this is the time to ask about your work with aircraft direction.

Rypinski:

That turned out to follow from the successful firing. At first I was told that some officers were coming from Oahu to look and see how our radar worked. And they wanted to do some things. That's fine. They came, and I set up the radar and tracked some airplanes for it, and they watched how we worked. Then they said, "We'd like to plot on a map the position of that airplane." And we said, "We need a table to hold the map up." [Chuckling] It's a little crowded here inside the van, so I don't know if we can do this on the beach, but we can telephone out the coordinates every fifteen or twenty seconds, and someone can plot it on the map with a pencil. But we have to orient the radar and map relative to each other. Because radar coordinates are azimuth, elevation, and range, pretty soon you see that what you do is you put a pin where the radar is, and a calibrated string or ruler to show the range. The string is pulled out at the angle given by the radar. The radar was arranged to calculate the difference between slant range and horizontal range. Horizontal range is a slant range projected against the ground. Plotting used horizontal range rather than slant range measured by the radar.

The 584 had two types of output devices: one was giant nine-inch diameter potentiometers, where the arm went around the periphery, and the relative proportion of the resistance between the arm and one end was the angle of rotation. Those were not used until we came to the M9 electrical director. Then there were also selsyns or synchros, which is a motor transformer-like device where the shaft position input at one is exactly reproduced at the output of another. It's a way of transmitting shaft angle with wires. That was the basic linkage between the outputs of the 584 and other equipment. But in azimuth there was both a fine and a coarse synchro. For the coarse synchro, one revolution of the shaft was 360 degrees. For the fine synchro, one revolution of the shaft was 1/16th of the circle or 22.5 degrees. There was sixteen times more accurate information from the fine synchro. If they were to be accurate, they had to have almost no load on the shaft. They would pull a little bit of load if you could tolerate a little bit of error. The synchros must have weighed three or four pounds and been six inches in diameter. It was a fair piece of iron. They were made to be pretty powerful because a rather minute force would make a small angular error. They had to turn dials and indicators, but not machinery.

So we did this manual plotting, and I very quickly realized that we could send the angle out to the plotting table, and if we just put the map down over the shaft of the synchro, then the azimuth would come out of the radar, and all we had to plot was the range on the ruler. I don't really remember the sequence in which all of these things were done. I have to deduce what I think happened to make the story fit. But very soon I said that if we put the azimuth synchro in the center of the table, I could wire out azimuth from the radar, and the plotter then would just plot range.

Nebeker:

You had another synchro that you could use?

Rypinski:

We had lots of synchros in the spare parts wagon. That was an easy part for us. Gears would have been another matter. So we did that, and they sent out some officers to direct the experiments. The name of the organization was the First Provisional Air Support Command, part of Fifth Amphibious Corps, I believe. They were pleased with what they saw. All we knew was we were plotting the position of an airplane we were tracking on a ground scale. All of the calibration involved, I was able to accommodate.

Nebeker:

How was the range done?

Rypinski:

Manually. A guy at the table had on headphones, and the range tracker inside the van just said, "Two thousand yards mark."

Nebeker:

He's reading it off a dial?

Rypinski:

He's reading it off an oscilloscope. The way the range tracker in the radar worked is that there was a circular trace on the tube. The circumference of it, if I remember, was 32,000 yards (nearly twenty miles). The target appeared as a radial blip on that trace, and then there was a transparent plastic fiducial, which was two lines drawn radially and spaced about the width of a pulse. So if this plastic mask was correctly aligned, the pulse began and ended between the two lines that were drawn. Now the range tracker had slew motors and a rate adjusting handle. He would adjust the speed of a motor so that the movement of the guides matched that of the target. If the target changed closure rate, he had to react. So most of the time he'd have the target within the lines, and some of the time it would gain or lose a little bit. There was some skill in maintaining that alignment and proper reaction to changes. I think there was both a fine and a coarse range scope, too, now that I think of it. You didn't track on the coarse scope; you tracked on the fine scope that maybe was a 2,000 yard window. This pulse kept going around the circle.

There were many ambiguities. I remember that the pulse had considerable width — nearly thirty degrees. The pulse was one microsecond wide, so at one microsecond that would be 150 meters per microsecond as the radar sees it. We were able to track not the pulse as a whole, but the leading edge on trailing edge. And eventually we defined how we were going to track that pulse as to what part of the shape intersected the fiducial as a goal, even if we couldn't hold it, so that we became consistent. When we did range calibration to survey markers, we did it the same way. In many situations we were able to state range to ten or twenty feet. I'm sure that we could give range to five percent of a pulse width (maybe we could do it better than that) with some consistency by this shape interpretation. What I didn't think about much at the time was that the width of that pulse was somewhat signal-level dependent. So if you have a strong pulse, it's wider than if you have a narrow pulse. But it happens that there's a gated automatic gain control in the radar, and I'm not so sure exactly what the amplitude-width relationship was. But I have no reason to think that it would change very much as a result of signal strength. As it happened, we were always more or less at the same range with strong signals when we were firing. This precision and range didn't matter as much at long distances as it did closer in.

Nebeker:

What happened after these officers looked at the radar?

Rypinski:

They went away, and everyone went back to work. A few weeks later something happened. I got orders to go on temporary duty to Oahu. My officers looked at this piece of paper with some wonder. It was apparently genuine and had come down through channels. So I presented my body at the Borking Sands  airport in accordance with the orders. [Chuckling]

Nebeker:

You didn't know more than that?

Rypinski:

I didn't know more than that. I was unloaded at Oahu in an hour. I reported as instructed, and finally I got to the people who wanted me there, and they said, "We would like to do some more experiments here. We've gotten a 584 radar, and we'd like to do just what you did for us on Kauai." Now I'm fuzzy. I don't know whether I did one more experiment and then set up four crews and four radars and got them all working and trained, or whether I went immediately to that stage on the basis of the Kauai experiment. I simply can't remember. The result of it was that the arm-and-synchro arrangement was prepared for what I knew later to be the Iwo Jima campaign.

Nebeker:

So you prepared four of these assemblages?

Rypinski:

It was essentially a hard surface table, and the synchro was mounted in the center with a ruler sort of arm on it and a little balancing so that the plot could be done. It was crude but far better than nothing. If people were just very careful not to load the synchro, it was fairly accurate. Certainly more accurate than the manual plotters who make a lot of errors.

Nebeker:

Did you know the purpose of this at the time?

Rypinski:

No. I knew that they were going to track airplanes and plot their position on a map. I can't remember when I met Colonel Galer, and there was another colonel; I'm not sure I can remember their names. Keil comes to mind, but I'm not sure that's right. And if I don't remember them now, I probably never will. There were some other officers, but they were the ones who were running the show.

Nebeker:

How long did it take, this building the four?

Rypinski:

I built these four tables. For the carpentry, I made drawings, and they had them built somewhere. They came back marvelously well done, so I had nothing to do with the plastic top or the table. They were about four feet square or something like that, so it could hold a pretty fair-sized map on it. You could just reach the middle from any side. This was all done rush. I'd say that from the tables, I guess, that I did my part in a few days, which was just to put the synchros on and make the ruler arm. Then they got crews together, and I trained them in how to operate it, which was not a big deal and fairly obvious. But there were some details that you had to get right about alignment and connection. The connection to the radar for a plotting table was not a normal connection. You had to understand how things were inside. Of course the external connectors for the radar information were bloody big, heavy-duty things, designed to be installed by plumbers. [Chuckling] But that was no more than they ought to be. The component design was, I'd say, 99.9 percent suitable for the circumstances.

Plotting Boards and Tables

Rypinski:

When these crews were all trained, I didn't know they were going to Iwo Jima. I was simply sent back to the anti-aircraft battalion a few weeks later, and they'd gotten along fine without me. They didn't miss me at all, which was disturbing. [Laughter] No more was heard. I never heard that those crews did very much at Iwo Jima, at least nothing that I can remember. I don't think that there was very much enemy aircraft activity. Time went by, and I got another set of orders just like the first one, to go to Pearl Harbor, and they said: "We'd like to do some more of this air support work with the 584 radar." The first thing they did was take me out to Barbers Point, which is a Naval air station near Pearl Harbor.

Nebeker:

Is that the southwest corner of Oahu?

Rypinski:

Yes. There's also Ewa, the Marine Corps Air Station, which is just west of Pearl Harbor. Guess we'll come into this later. What they showed me was a 584, and it had a plotting board with a table. You'd put the map down, and a light spot tracked around on the map where the airplane was. I looked inside of this, and there was a fairly elaborate servomechanism essentially to position the light with some substantial power for machinery. It becomes an art to make something like that move fast when it has weight to it. They said this plotting board was built at MIT or maybe Westinghouse. I don't remember now. My recollection is MIT, but not necessarily. They said that it would cost several hundred thousand dollars to buy another one, and besides that it would take six months to get it. "Now what do you think you can do to provide the same function?"

At that time, and in that year, I was very brave about saying things. I thought of the synchros and some different ways of doing it that wouldn't overload the synchros. And I said, "Well, I think that in a week or so I can build a machine that would do the same thing." So the next day I'm trying to design it on paper, and the room where they gave me a drafting table happens to be the Air Intelligence Analysis Room at MCAS Ewa with all these photographs. While I did my work, I soon noticed that they had lots of pictures there of Okinawa. I did my work and decided how I was going to make this machine and some dimensions. I made drawings for the carpenters so that this time they could make the table with a glass top that was fairly strong. The Iwo Jima tops didn't have to be glass. There was no light shining through. It just had to be a table. And the way this newer table was arranged, there was a shelf or the second table level about a foot below the glass level, and the glass level was designed to be a good working height for people who were going to put pencils to it and make marks on the map. The machine, the azimuth part of it, used the fine synchro. So I had a sixteen to one power improvement on azimuth information, and I used the gears that did that same ratio in the M7 director. So to get gears I used M7 director spare parts which reproduced exactly that same ratio set. This machine looked something like a crane. The central platform of the crane had a big gear, and then the synchro driving it had a 1/16 pinion gear to drive the whole platform. There was another synchro sitting in the center of the rotating assembly, which was a range synchro with a drive pulley mounted on the output shaft driving threads to another pulley on the end of a swinging arm. There was a tiny mirror at a 45-degree angle so that the focused light shining out from the center was reflected upwards by the mirror to project the light spot through the table top and map above. In a dark room you could see that.

Nebeker:

So you could see the light spot through the map?

Rypinski:

Yes. I built one of those machines, and it was soon tested. Of course there were detail improvements possible. But it substantially worked.

Nebeker:

And how long did it take you to get that whole thing?

Rypinski:

I did it in less than a week. The first day I rounded up parts, and they assigned an officer and a jeep, and this officer had the authority to draw parts from these spare parts depots, and we just went around and collected the parts that I needed from various places, that is synchros and gears and pulleys. Then they took me to a sheet metal and machine shop, at Ewa Marine Corps Air Station. That shop was used for engine maintenance at the Marine Corps Air Station, and they had lathes and mills. All the pulleys and round parts I made myself on the lathe and there were a few parts that weren't round that they made for me on the mills. There were sheet metal parts where I used aluminum for airplane skins and hacked those out. The sheet metal parts were mainly used for the rotating assembly holding the range synchro, pulleys, light source and mirror. So all of the stuff that moved was as light as I could get it, but nothing really mattered too much after I mounted the range synchro. I may have had something clever so that the range synchro didn't rotate, but I can't remember now.

Nebeker:

Okay.

Okinawa Campaign

Rypinski:

After the first model was constructed, I went back to my battalion. The orders for these things were one week or extendable a week at a time or something like that. I wasn't back at Kauai very long before I got a different kind of orders. This set of orders was in effect transferring me out of the battalion to an indefinite category of some kind at Pearl Harbor to do work with the Air Support Command. They asked me to build four machines and four crews again for a future operation (Okinawa). I'm really worried about having addled these numbers and events. The gross event is clearly separated, but the details of what I did at each step worries me. Maybe I only built one machine for Iwo Jima. But in any case, I came back and built four more machines, and we went through the same cycle again, and trained the crews. And the same thing happened. When I was all done, the crews went off and disappeared, and I stayed at Pearl Harbor. After the machines were built, we did some exercises with planes sent up just to exercise the machine and the plotting process. Colonel Galer was much appreciative of my effort, and the way he showed it was he decided he'd go up and fly for me. There's sort of a lore among pilots that they don't take ground direction from anyone but other pilots, preferably ones that they know. Those who give flying instructions from the ground are qualified to do that. But what he did was say, "I'll go up and fly, and you do the exercise that you've been doing, with me."

Nebeker:

So you were directing him on a certain course, is that it?

Rypinski:

Yes. It was a little more complicated than that. It involved coordination with real ground-observed and radar ground positions.

That was very thrilling. Colonel Galer had a Congressional Medal of Honor, and that had an effect on his authority beyond that of mere rank. He was an officer of much influence. That was a very interesting phase.

Nebeker:

So it sounds as if that was quite a success.

Rypinski:

Yes. At least from the construction and training stage. Now it was a long time later before I heard about what happened. I got a letter that told me about it, which I still have. But I haven't had enough time at home to dig it out of a safe deposit box and bring it. I'll put a copy of it in the mail. From the radar officer of the battalion.

Nebeker:

That letter tells about the use?

Rypinski:

Some of these uses. My understanding was that there were three kinds of important uses: first, the 90-mm battery wasn't much needed for anti-aircraft. So they were used as field artillery where a rifle trajectory, that is a flat trajectory, was suitable. Which was all right for shooting at mountains from the valley. The next thing with the radars, they did interceptions. That is, they'd see an enemy plane at night, and they could direct an interceptor to it. The next thing was artillery spotting, where if they saw a flash on the ground from enemy fire, the pilot could fly over it and say "Mark" when he was above the target, and then they would have the target coordinates from the radar. Once they had that, they could send counter fire. Those were the main uses. But there was one very special matter. The Japanese held the Shuri, Naha, Yonabaru line across Okinawa for a long time. It was very strongly held and unsuccessfully attacked for a long period of time. That's in the history books. But eventually the Marines got into Shuri Castle, which was on top of a hill, and they had to climb the hill. They did this, they climbed the hill in rain and fog, which is why they were successful, because the defenders couldn't see them. Then they did certain things by air drop, and all of the air drops in support of the Marines were controlled by this radar positioning. I was told that the radar was very significant in finally breaking that Japanese position.

Nebeker:

What was this tracking device called?

Rypinski:

I never called it anything. [Chuckling]

Nebeker:

How would you refer to it now? Could you give it a name?

Rypinski:

I guess it was called an automatic plotting board. If you wanted to track, you still had to put pencil marks on it, but you didn't have to figure out where to put them. You just put them around the light spot.

Nebeker:

Over the light.

Rypinski:

I think they were called plotting boards, 584 plotting boards, at the time.

Nebeker:

And as you say, there was at least one made to a different design.

Rypinski:

Which was nothing but the synchro and a ruler or a scale off of the center. Yes.

Nebeker:

Well, the one that you said was a couple hundred thousand dollars?

Rypinski:

Yes. That was made by somebody else. I only made one kind. And that was the only other one I ever saw. I simply wasn't in a position to see more than my own scope. I think the Navy ships had plotting boards routinely. I rather would guess that the CICs had them, but they were very elaborate pieces of machinery that you wouldn't carry on a landing. So it turned out that after this was all done, I was sitting in Camp Catlin near Pearl Harbor with nothing to do, and after about a week of sitting, I decided I had been forgotten and asked for instructions on what to do. So I went down to the Navy yard, and I saw the chief personnel officer for signal personnel, or something like that. I went to see him, and I said I thought that I wanted to go back to my battalion where I'd come from. That seemed like the reasonable thing to do. And he says, "Well, we can't do that." [Chuckling] And it turned out the reason he couldn't do that was because they'd landed on Okinawa already. No, they hadn't landed; they were on the way. He wouldn't say why. He said, "We're going to keep you here at Pearl Harbor where we can find you if we want you." [Laughter] And that's exactly what they did. I was assigned to radio maintenance in Pearl Harbor, and I labored on maintaining radios and radio intelligence trailers and stuff like that for several months until they started preparing for the Japan landing. Then I went through a like-type cycle, I think, for eight crews and eight plotting boards for 584 radars.

Nebeker:

A what cycle?

End of War

Rypinski:

A similar cycle, like-type. This time they didn't forget my orders, and I was going with the crews on the landing. Just after VJ-Day I was with the Fourth Marine Division on Maui. This division was just going on board ship for the landing at Kyushu. We had packed our radars. They went on supply ships somewhere. We never saw them after that. But our bodies were destined for Kyushu.

There is a possibility that one of the guys who's alive because they dropped the A-bomb is me. I think I had a different way of looking at it at the time. We now have philosophical hindsight. So, that's about the story of that cycle.

Nebeker:

You then stayed on in Hawaii until your discharge?

Rypinski:

Yes. It took them a while to turn off the war. They didn't just do it overnight. On VJ-Day I was still at Pearl Harbor. But within a few days after that I was on Maui, and I saw the display of VJ-Day at Pearl Harbor. Every ship in the Navy yard was shooting off rockets. The news came in in the early morning Hawaiian time. It was VJ Day when they signed the papers on the Missouri. That was the definition of when the war was over. I think. It may have also been over when the President said it was over. That was Truman.

Nebeker:

It was August 15th. The unconditional surrender was announced August 14th, but they list here VJ-Day as the 15th.

Rypinski:

Well, the announcement was what was celebrated.

Nebeker:

Yes, the 14th.

Rypinski:

Yes. Because we got it during the day that it was probably going to happen, and it became credible when the President went on the radio and broadcast that it was fact. So that was our definition of when the war was over. Everyone went wild. That night I drove around the Navy yard, and it was Fourth of July. A few days later we were on Maui. But it took about a month to get things turned off. After about two or three weeks they decided that they weren't going to need this air support radar in the Fourth Division. The whole thing was packed up and we were all returned to our previous situation.

M7 and M9 Electrical Directors

Nebeker:

You had something you wanted to say about the M9 electrical director?

Rypinski:

Oh, yes. The M7 director and the 90-mm guns were one generation. There was another generation with the M9 electrical director done by Western Electric, and 120-mm anti-aircraft guns with automatic fuse cutters. Very few of those got into service, and those that did were right at the end of the war. They had one M9 director in the Pacific that they sent around for each battalion to work with for a day so that they would have seen it before, and presumably it would replace the M7. It had a considerably better prediction capability and greater flexibility and range. The M7 was entirely a mechanical computer, with three-dimensional cams, differentials and ball disc integrators.

Nebeker:

Did you ever look into how the M7 worked?

Rypinski:

Oh, yes. I still have an instruction book.

Nebeker:

[Chuckling] Did you do any work on the M7 when you were with the battalion?

Rypinski:

No. I worked with it, but never on it.

Nebeker:

That was not your responsibility. Is there anything else you can think of that you'd like to comment on about the 584 or anything else with radar in your experience during the war?

Moving-Target Indicator and CW Jamming

Rypinski:

We did some experiments, something called MTI, Moving-Target Indicator. I tried some unsuccessful experiments with frequency notching. If the target's moving, there's Doppler shift, and I didn't have the means to really do that experiment.

Nebeker:

When did you do that?

Rypinski:

We just did it as an experiment on my own initiative and got no result, for reasons that I understand very well now but didn't then. We had exercises with chaff or window and with CW jamming. And they worked.

Nebeker:

You mean the jamming worked?

Rypinski:

Yes. I got interested in whether I could get rid of the CW jammer with a single-frequency notch in the IF strip, but I was in no position to really do anything. The 584, you could just see that there was a great deal of extension possible on the operating principles that were already there. You could imagine more range, and more power, and even some resolution improvers. The things that wore out weren't too numerous or too often. I think the transmit-receive switches, which were spark gaps, didn't last. They were wear items. I don't think we ever replaced any motors because I don't ever remember replacing a motor on it. Or a tire. [Chuckling]