Oral-History:Leo Sullivan
About Leo Sullivan
Sullivan received his BS in Physics from MIT in 1940. His undergraduate thesis was on building electron microscopes, and he spent the next two years as a research assistant to Prof. George Harvey at MIT, continuing his work on electron microscopes. In June 1942 he switched to the MIT Rad Lab, working for Ivan Getting in the fire-control division. His electron microscope experience came in useful, since the microscope required a great deal of power supply stability, something radar equipment also needed. He worked on the XT-1, later renamed the SCR-584, for the duration of the war. He did a great deal of maintenance and operation, first on the experimental models, and then in the field. He went to North Africa, Italy, England, France, and Belgium, and would have headed to the Pacific Theater if the war hadn’t ended. In addition to maintenance, and training Army radar crews to operate the SCR-584 properly. He also worked on adapting the 584 to function as an anti-V1 device, and as a mortar tracking device. After the war he worked for the L. H. Terpening Company, the Applied Physics Lab at John Hopkins (1948-53), and the Lincoln Labs. At Lincoln Labs he continued working on radar developments, for for continental air defense, though as it turned out the product had meteorological applications.
About the Interview
LEO SULLIVAN: An Interview Conducted by Frederik Nebeker, IEEE History Center, 14 June 1991
Interview # 100 for the IEEE History Center, The Institute of Electrical and Electronics Engineers, Inc.
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It is recommended that this oral history be cited as follows:
Leo Sullivan, Electrical Engineer, an oral history conducted in 1991 by Frederik Nebeker, IEEE History Center, Hoboken, NJ, USA.
Interview
Interview: Leo Sullivan
Interviewer: Frederik Nebeker
Date: 14 June 1991
Location: Boston, Massachusetts
Education and Recruitment to Rad Lab
Nebeker:
I'm talking with Leo Sullivan on the 14th of June 1991 in Boston. This is Rik Nebeker. Could I ask you about your background and education?
Sullivan:
I went to MIT and got a B.S. degree in physics in 1940. My thesis was on building electron microscopes. I stayed on for the next two years as a research assistant in the physics department, still working on electron microscopes with an associate professor, George Harvey. Then one day it became clear that the world was no longer interested in what we were doing, and it was suggested that I go across the parking lot and interview at Radiation Lab.
Nebeker:
This was in '42?
Sullivan:
That was in June of '42.
Nebeker:
You went across on your own initiative?
Sullivan:
As a matter of fact, one day, George Harvey actually said, "I don't think that the world is interested in what we're doing anymore, Leo. So you why don't you go over and talk with people at Radiation Lab." I think that he'd had a conversation with someone over at Radiation Lab. So I went over and was interviewed by Ivan Getting and ended up in his division. He was head of the fire-control division, both ground-based and the Naval fire-control effort, anti-aircraft fire control. I ended up working on the ground-based anti-aircraft equipment, starting out with an experimental radar, an automatic angle-tracking radar, which is actually the first one in all of history (the XT-1). It was highly experimental. It used the twin 50-caliber machine gun turret out of a B-29 off the production line from and we mounted a five-foot antenna on it. The bulk of the rest of it was pretty much designed and constructed at Radiation Lab. By the time I got there, the XT-1 was being tested and used to track aircraft in an experimental measurement program. It was used to demonstrate just how accurate the tracking could be made.
Nebeker:
Did you have a particular assignment when you joined?
Sullivan:
Strangely enough, the first assignment I ever got was very prosaic. The day I walked in to see Ivan Getting he asked me if I could run a milling machine. I said, "yes." He said, "Well, we need someone to make a gear box for the antenna." I guess the machine shop the official machine shop was saturated. I'd had a fair amount of machine-shop experience in the course of my physics training. So my first assignment was to make a gear box. Very quickly I ended up working in the whole system. There was a small group that included Lee Davenport, Hank (Henry) Abajian, and George Harris who were heavily involved with it. I joined that group and, working with them, learned the whole system.
Nebeker:
How much electronics experience did you have?
Sullivan:
I'd had a fair amount. In the course of designing and building this electron microscope, we built all of the power supplies. That sounds sort of prosaic except that the power supply stability has to be exquisite for an electron microscope. The variations in the magnetic coil covers, and also the high voltage, can only be somewhere down in the thousandths of a percent in order to get the resolution.
Nebeker:
Was that much finer than ordinary power supplies?
Sullivan:
Yes. You just couldn't find much of anything. As a matter of fact, there was very little on the commercial market in those days, even test equipment. A multimeter or an oscilloscope was a curiosity. I can remember in the physics department we managed to get the funds for an oscilloscope — I don't know whether it was an RCA or a Dumont — and an RCA volt-ohms multimeter, and they were a curiosity. I think those were the first sophisticated pieces of instrumentation that were ever bought in the physics department.
Nebeker:
What year was that, roughly?
Sullivan:
I guess that must have been between '39 to '41. Most likely in '40, perhaps '41.
Nebeker:
So you were active in a sense as an electrical engineer, electronics engineer, on the electron microscope?
Sullivan:
That's right. In addition, I'd rebuilt the whole microscope from winding the magnets to doing the glass-blowing. There were very few industrial, commercially available components. As a matter of fact, I think when we started out in the late 'thirties you could not buy a commercial vacuum pump. We had to make them all. It was only later on, somewhere around 1940, that the first of the high-speed distillation — or vacuum — pumps became available. There was a period when you couldn't buy an ionization gauge; you made it. I think it's almost accurate to say that you made just about everything.
Nebeker:
Did you know about the radar device before you came to Rad Lab?
Sullivan:
Oh, no. It was secret and when you were interviewed at Radiation Lab, they did not tell you what you would be working on. You joined on faith and were told that it was an interesting effort, a big effort, and a vital effort. That's all you ever learned before you joined.
Nebeker:
But because you were at MIT, you knew this was very important and that important people were working on it?
Sullivan:
I really didn't know anybody who was there. Later on when I joined up, I discovered people that I'd known in the physics area: Ken Bainbridge from Harvard. This fellow I worked with, George Harvey, later on joined Radiation Lab. A number of the people at MIT did join the Radiation Lab. Some of the physicists that were already there, I knew when I got there. It was pretty well spread around the countryside.
Nebeker:
Were you immediately briefed on what was going on there?
Sullivan:
It was a gradual process. I was shown around, and it was an eye-opener. It was a step-function eye-opener to get shown the sophisticated equipment that I'd had no inkling of, like the whole microwave scene. No one outside of that community was even aware that you could generate such high powers on wavelengths as short as 10 centimeters. Then when I got introduced to 3-centimeters, that was mind-blowing. There had been for example, low powered wavelength devices that provided power for magnetrons. That was really one of the big breakthroughs, as you well know. But the 10-centimeter high-powered magnetron really made possible a whole family of equipments with many different applications, and many radars.
XT-1 Group
Nebeker:
How large was the XT-1 team you joined?
Sullivan:
There were somewhere around four or five. We were involved with the system and in putting the components together. In the meantime, we depended on the components groups for the components used for the radar. We worked very closely with the Rf group and the magnetron group. There was the receiver group, the pulser, and modulator group. I can't really come up with a number, but there were a large number of components groups. They supported us; we depended on them completely.
Nebeker:
What tasks did you take on?
Sullivan:
First of all, I learned maintenance and operation and participated in the aircraft tests. Then I drove the trucks around. It was a very lean operation. The younger generation was subject to the draft so you had to be well connected to something pretty important. As a result there was not a large supporting cast. If the trucks had to be driven — and I mean, anywhere in the United States — usually we ended up driving them ourselves. If a motor generator or if a gasoline-driven generator broke down, we rebuilt it. You either stood there and looked at it, or you did it. [Chuckling] As I say, it was a pretty lean operation. I think I ought to point out that in the beginning the testing was done out at Fort Heath at the tip of the Winthrop Peninsula, just north of Boston. We would set up out there and did a lot of aircraft tracking. The name of the game was an evolutionary improvement in the tracking accuracy of the radar. It had to meet certain angular tracking requirements to be really useful in the anti-aircraft fire control role. It was really designed and built for automatic angle-tracking, gunlaying radar for the heavy anti-aircraft guns, and for the 90 mm guns.
Nebeker:
You'd take it out for testing and try different things?
Sullivan:
Improvements and so forth. Yes. We'd track the aircraft targets. We had a cine-camera mounted on the antenna, and we'd photograph the ____ vertical. The way you'd measure the tracking accuracy was to take the film, read it and measure the angle of the deviations from the reference. That was where it got its report card marks and where we got our report card marks. Eventually it was certainly clear that it would make a useful anti-aircraft gunlaying radar.
Testing and Electronic Analog Computer
Nebeker:
How long did that phase of your activities last?
Sullivan:
I guess it was I'd say into late 1942 out at Fort Heath. Then we took the radar — and I'm a little hazy on the date down to Camp Davis in North Carolina, which was the Army's Anti-Aircraft Training Center. Also located at Camp Davis was the Coast Artillery & Anti-Aircraft Board. They passed judgment. They were responsible for overseeing the testing, the equipment selection, and ultimately the recommendation process for the equipment procurement.
Nebeker:
That's where you really sold the device?
Sullivan:
That's right. That's basically where it was sold. The Army was extremely interested, and we set up to fire using the XT-1. In the meantime, the XT-1, the radar, had been being developed. Bell Laboratories had developed the first electronic computer, which was an electronic analog computer to replace the older, antiquated mechanical anti-aircraft computers. That computer solved the fire-control problem. They were tight on flight, and you had to read ahead.
Nebeker:
Did this XT-1 give any range information?
Sullivan:
Yes. It measured range. We transmitted to the M9 computer. We transmitted range. As a matter of fact, the coordinates transformation, from angular coordinates to rectangular coordinates, was actually made in the radar. There was a feedback array back and forth between the radar and the computer. We measured the range, and there was a range potentiometer, so you had a range voltage. You had a voltage that was proportional to the range. You then took that voltage, and there were potentiometers on the elevation axis directly driven, and also on the azimuth axis. The elevation potentiometers had a sine card and a cosine card. If you put the range voltage across each one of these potentiometers, then out of the arm on the potentiometer, you'd get the range multiplied by the cosine and the sine. Then you could also get the horizontal range. If you took the horizontal range, and took that voltage, and applied it to the cosine and sine plots, of the potentiometer's on the azimuth, then you could get x and y. Out of all of this you'd end up with rectangular coordinates, x,y height.
Nebeker:
So interesting to hear how that calculation was done in a physical way, instead of electronically.
Sullivan:
The great advantage was that for a straight line, constant-altitude, relatively-constant-velocity course, the rates were variant, the derivatives in rectangular coordinates. Then you had to compute the time of flight, and then get an incremental component in x and y, and also in height. Then that would be translated back into angles for the elevation and azimuth.
Nebeker:
That translation was done in the radar?
Sullivan:
That transformation was done in the radar, but the computer did all of the computing. For example, it computed the derivatives, it computed the ballistic corrections, and the altitude density corrections. Then the computer had to compute the time of flight. The time of flight had to be sent into the time fuse on the shells. In the early days the shells required a time fuse. There were four guns per battery that were commanded by the single computer (the M9 computer). You transmitted the azimuth, elevation for the angles for the guns. And then at the same time, you transmitted the fuse time. Then you took a 75-pound shell, stuffed its nose in the fuse-cutter, and it would set the timer. You would put it in the breech, and off it went. I suppose the four guns could fire, maybe up to 80 rounds per minute. But that's tight. Each one of those shells weighed 75 pounds and that turns out to be a lot of weight that has to be handled when you're in action. I remember one night we fired a thousand rounds. Hell, that's a lot of ammunition. That's a lot.
Nebeker:
A thousand rounds in testing?
Sullivan:
Not in testing. Oh, I'm sorry. No, this is in action. I'm jumping the gun. In testing we'd just take the radar to the M9 computer into a single gun. I'll go back to the demonstration at Camp Davis. The Secretary of War, Henry L. Stimson, "A Grand old man" at 76, came out. He sat down in the director's chair on the beach there. They flew a radio-controlled Culver Cadet Drone up the beach. It paralleled the beach and climbed to 6,000 feet. We initiated the track, and waited for the computer to settle down. Then we fired. It only took us about six rounds to blow it up. After that Secretary Stimson got up and went to one of his aides and said, "We'll buy that." One of our guys overheard him say to one of his aides, "My God! Are they all that young?" See, we were all pretty young. I mean, the oldest of the lot was maybe three years out of grad school. The rest of us were maybe two or three years out of a four-year school. We had some pretty young-looking guys, I guess. That was the turning point. Then we had the whole backing of the upper reaches of the government, of the War Department and the procurement people.
Nebeker:
At that point did it go into production?
Sullivan:
I don't know whether that really triggered off the production design. I think perhaps the production design had been started before that. The Anti-Aircraft Board people had looked very favorably on the equipment. I think as a result of that, the production designs were started. As a matter of fact, the production designs were started when the equipment was in rudimentary shape. It was highly experimental. But it provided a head start, so that when the decision was made, production went much more rapidly. It had a substantial head start. They must have produced somewhere around two or three thousand within a year and a half. I'm a little hazy on that number, but it's in the multiple thousands. Then they started going out into the field in late '43, or early '44.
London Mission
Nebeker:
It says here that you had this assignment until September of '43.
Sullivan:
No, that's not right. Let's see. I'm not much of a notebook keeper or a log keeper. I didn't leave the US to go overseas until '44, March of '44. Some of these radars were in the field at the end of 1943 into early '44. I first went from the US in March of '44 to London. As a matter of fact, I had orders to go to North Africa. But what happened was that the British had had news of the German V-1. Their intelligence people had told them that the Germans had this V-1, vengeance weapon. The British had excellent information on it. But they did not know when they would start firing it. North Africa in the Mediterranean Theater, was out-prioritized by this special task. So somewhere around ten or eleven of us were sent to England, at the end of March in '44.
Nebeker:
Were you still employed by Rad Lab?
Sullivan:
Oh, yes, throughout this whole business we were employed. There were only two of us from Rad Lab. The other people in that group were proximity fuse people from the Applied Physics Lab at Johns Hopkins. There were one or two people from Bell Labs, who were experts on the M9 computer. Hank Abajian and I went to England around that same time. At that time the Germans were raiding London pretty heavily with aircraft. I remember the night before I got there, they had about a 180-plane raid. I stayed in England almost a month I would guess. I got there in March and left late in April. Then I continued on, following my original orders, to North Africa, which was the Mediterranean Theater. I was at Port Lyautey in French Morocco in April. Then I guess I landed on the Anzio beachhead to work with the anti-aircraft batteries on 4/24/44. I think when I got to Anzio, I was so impressed by the war that this was the last entry in the diary that I ever made. That was it. [Chuckling] I got flown to Algiers, where I stayed for a short time inspecting the anti-aircraft batteries that were there.
Nebeker:
They had the 584 there?
Sullivan:
That's right. The 584s had reached North Africa and Italy and Anzio. But the war pretty much left North Africa. So then I worked with the anti-aircraft batteries in southern Italy. Then I later ended up on going to Anzio. That was very active with a lot of aircraft.
Anzio and Performance of 584's
Nebeker:
Tell me about your Anzio experience.
Sullivan:
I went up there from Naples in a stripped-down PT-boat, one of these air-sea rescue boats; they used them as taxis. They'd get up there in a hurry. It was about a four-hour run at full tilt.
Nebeker:
Was that dangerous in itself?
Sullivan:
It was not all that bad. I guess, the Navy liked to go as fast as they could pretty well offshore. The Germans held a good part of the upper part of the peninsula at that time. We landed at the jetty. I got picked up and went out and spent most of my time with a single battery. When I got there, I discovered that the RC-184 IFF equipment had arrived. There was an order that had come down from on high that they be installed in each of the batteries. Well, nobody on the beachhead had ever seen the equipment. I was the only one who knew anything about it at all. So I was tagged with the assignment of supervising the installation of the IFF in all of these batteries. That was a busy trip.
Nebeker:
Did you have experience with that or training in that?
Sullivan:
I had to learn the equipment back in England. As a matter of fact, I got commandeered into learning the equipment in a hurry when I went out to give a one-day course at a British Anti-Aircraft Training Unit Center. I just read the book and then took the equipment. [Chuckling] Somebody followed and read the book, while you tried to figure out — do what the book said. The cream of the jest was that after installing all of this IFF equipment, it turned out that Anzio wasn't in an artillery zone, which meant it was a free-fire zone. I don't know how it was earlier, but it may have taken a while to really establish that doctrine. In a free-fire zone anti-aircraft could fire at anything they saw in the air. Otherwise the identification process takes too long for that small an area. By the time you get everybody convinced as to whether it's an enemy or a friendly, it can be too late.
Nebeker:
Even with the IFF?
Sullivan:
They didn't have the IFF for a long lag time. Let me go back. I would hesitate to put it quite this way, I guess I should. But in any event, I did some work with Abajian on the anti-aircraft defenses of London. There you had to have identification before you could fire. You had to decide whether it was a friendly night fighter or a German aircraft because the British had night fighters operating over London. There was a great reluctance to fire in the face of any uncertainty. So as a result it took a bit too long, I thought. Now I'm not too sure that everybody thought it took too long. In contrast, Anzio was an inter-artillery zone. You'd just shoot.
Nebeker:
So in a sense that was wasted effort, putting in all that IFF equipment?
Sullivan:
Sort of. Maybe I shouldn't tell that story.
Nebeker:
Were there many German aircraft overhead at Anzio?
Sullivan:
They raided fairly frequently at night. In the beginning they had difficulty holding the beachhead against German aircraft. But by the time I got there, the 584s had been there for a while, and the anti-aircraft had worked up a pretty score. On a raid they could easily get a 50 percent, 60 percent kill ratio.
Nebeker:
Is that right. Night raids?
Sullivan:
That's right. I was there for a couple of weeks. I don't remember a day raid.
Nebeker:
Why is it that the Germans made night raids? Would there be a higher kill rate for a day raid?
Sullivan:
Yes. Then everybody could fire. The night raids required the radar, the heavy guns.
Nebeker:
There were a lot of lighter anti-aircraft?
Sullivan:
That's right. Lighter anti-aircraft guns that used visual sighting.
Nebeker:
Was the visual sighting good enough?
Sullivan:
Well, if the planes came in low enough and into a short enough range, it was. The high rate of fire length of the 40 mm guns might get a fair kill rate. So as I say, by the time I was there, in the late April, May period, they were raiding only at night. I remember seeing one German aircraft the whole time I was there, and it was a photo recon, I'm sure. He was way up at about 30,000 feet. But the predicted fire, even with the heavy, high muzzle-velocity gun, like the 90 mm gun, the time of flight is somewhere around 31 seconds. So you fire, and it takes that long for the shell to get up there. If you miss, and he sees the burst and turns, and you upset the predictions, which is a linear extrapolation. He's going to keep flying that straight-line course. By the end of World War II, I think it became pretty clear that predicted fire at long ranges and high altitudes required guided missiles. But the technology didn't quite exist late in World War II.
Nebeker:
Your job at Anzio and in North Africa was to check out the 584s?
Sullivan:
That's right. If they needed any instruction or help with the maintenance and had some problem radar, I'd work on that and get the radar going. But on Anzio I found the level of operability and performance was high. I'm not sure if it's a sound judgment, but it may be correlated with the fact that they were defending the prime target, and the prime target was them. It wasn't a very large area. It was only about an eight-mile land mass. The Germans held the rest. I think I can honestly say I don't think I ever saw a higher quality and a higher level of performance in anti-aircraft units and radar maintenance people and operating people than I did on Anzio.
Nebeker:
How reliable was the 584 generally?
Sullivan:
I'd say it was highly reliable.
Nebeker:
What percent of the time would a unit in the field be in good working order?
Sullivan:
On Anzio it was very, very seldom that there was a single radar out of commission at night. If you could count on the whole day to do the maintenance and check-out, you'd go into the night in pretty good shape.
V-1 Rockets
Sullivan:
<flashmp3>100 - sullivan - clip 1.mp3</flashmp3>
Well, it turned out that in June of '44 the Germans started to launch V-1s at London from across the Channel. The British and American batteries started out using the anti-aircraft batteries around London. It very quickly became, obvious that that was not a great idea. Even if you shot one down and it didn't explode in mid-air, it would come down somewhere. So they finally concluded that the thing to do was to establish the anti-aircraft defense system along the whole south coast of England, along the Channel. Eisenhower gave the British a large number of 584s. The British had modified the Bell Labs M9 computer for the ballistics for their 33.7-inch heavy anti-aircraft guns. So along with the 584 and their computer and those 3.7s, they could do a very creditable job of air defense. I'm not too sure about the numbers, it's in the history books — but there must have been at least 50, maybe 40, American batteries that were assigned to the coastal defenses there.
Let's say you started somewhere around Folkestone, Dover, Hythe I think Rye, Dymchurch. Starting out at the eastern extremity — along the coast you had all of these anti-aircraft gunneries dug in. They stopped far short of Brighton. But it covered the main path of firings from the continent — either from Belgium or from Holland, and from the French coast in the beginning. But then the other advance that made a great difference was once you were down on the Channel, then you could fire proximity with impunity. Fire proximity fuses from low elevation angles because these V-1s flew at only about 2,000 feet. The proximity fuse that was in production was for 9 mm anti-aircraft gun projectiles. These batteries were all installed in quite a rush. A lot of them were poorly trained, and in the beginning they had a poor score.
Normandy and Close Support Bombing
Nebeker:
Were you in England at the time?
Sullivan:
I'd come back. I ended up going back via North Africa to England. By that time I was back in England. But I've gotten out of order. I was assigned to another program actually, not too long after D-Day. I went into Normandy with the Ninth Tactical Air Command. I was in North Africa. They'd developed or invented a technique for ground-controlling and guiding fighter bomber squadrons, diver bomber missions in the British Branch of the Radiation Lab at Great Malvern. The technique involved a large plotting board. It had a scale such that it matched the scale of the maps in Europe on the continent. It kept track of the planes with a little light spot. As the radar would track the squadron leader, the spot would move around on the map and give you a very accurate indication of where the aircraft was and where the squadron was. These were almost entirely P-47s, the Thunderbolts. They carried a pretty heavy bomb load.
Nebeker:
They would be directed back at base?
Sullivan:
No, from the radar that was situated, say, anywhere from five or six miles to, say, 12 to 15 miles behind the front lines. When I got back from North Africa, I got connected with that program.
Nebeker:
Did that use the 584?
Sullivan:
Yes. The 584 drove the plotting board. It had some very rudimentary plotting aids that helped to bring the aircraft in on the target. Then by radio command we would guide the aircraft. In other words, we would talk the pilot on and guide him onto a target.
Nebeker:
Were you involved in that?
Sullivan:
Yes.
Nebeker:
Talking with the pilots?
Sullivan:
Yes. I can remember a couple of the call letters. One was "Cheetah," and if you wanted to talk to the squadron leader, it was "Cheetah Leader." There was another squadron that had the code name "Ocean Purple." We would, as I say, guide them in. Also the P-47s were very primitive. They let you go in at 8,000 feet. We would draw a circle with a radius of 8,000 feet. Now you've got a circle with a radius of 8,000 feet and just a target. The name of the game was to bring the aircraft in tangent to the circle. You could come in from any direction just as long as you hit the tangent. Then there was a plastic scale. The pilot would fly at a standard speed. We would give him a countdown. When we gave him 0, he was supposed to see the target off his left wing, and then he would roll. He would pull up, and then roll, and dive at 45o. So that's where the flying at 8 and the radius of 8 came in. We also guided some British Spitfires.
Nebeker:
Did guiding the P-47s work fairly well?
Sullivan:
Oh, yes. We could bring them in. One of the major objectives was to bring them in on a ground target during very poor overcast weather. They would dive through the overcast and break out at maybe a thousand feet. I remember the demonstrations. One of the demonstrations we put on in England before we went to the continent. They had a Spitfire squadron, and I think one of the most startling bits of flying I've ever seen in my life was to see a squadron of Spitfires come out of the overcast in formation. The ceiling was not all that high. It was a pretty gutsy affair. But it sold. You know how military techniques sell on the basis of successful demonstrations. Then and today.
Nebeker:
That seemed to be enough? If they could be shown in demonstration that they worked, the Air Corps people were willing to by?
Sullivan:
Yes, that's right. Of course the development had been going on at Radiation Lab. But it hadn't become an official program, as far as I know. Just as soon as we got a 584 modified and got the plotting board, then the Ninth Tactical Air Command decided, we'll give it a try in action.
Nebeker:
What was that system called?
Sullivan:
It didn't have any code name that I remember. We called it the close-support bombing system.
Nebeker:
Close support?
Sullivan:
Yes, it was basically close-support bombing.
Nebeker:
Whose idea was that, do you know?
Sullivan:
I don't know. I wasn't in on the birth. So that by the time I got back to England from Africa, it was pretty well underway. They'd started the design and the construction of the plotting board. I'm sure it's in Guerlac's history?
Nebeker:
Yes, Guerlac's history.
Sullivan:
Yes. It's in there somewhere. I don't think I'm mentioned by name in there. I am in a number of other places in there. But not in the close-support bombing bit. The radar, the plotting system, the ground were all operated and maintained by a platoon of the Signal Corps Air-Warning Battalion. I think it was the 555th Air-Warning Battalion. They were responsible for the radar end of it and supported the Air Force of the Tactical Air Command. As a matter of fact, we operated directly with the Ninth Tactical Air Command headquarters, including the commanding general, Pete Masda because their TAC headquarters had a very strong interest in the successfulness and the viability of that technique. He was the right guy to command a fighter bomber squadron. As a matter of fact, after the war he became the head of the FAA here. He ended up owning a ball team out on the West Coast. But anyway, I had a few interesting conversations with him on how you easily acquire the right squadron. You've got all sorts of aircraft milling around over Normandy, so it's a bit of a trick to find the right squadron. But you'd usually manage it.
Nebeker:
So that was shortly after D-Day?
Sullivan:
It was D plus 20, D plus 26, that we went in and lined up the radar off a cargo ship, Liberty ship, and down into a landing craft and ashore we went. But by this time there was no opposition on the shore. The war had moved inland. The line ran through Saint-Lo pretty much east and west in sort of an arc then came around through the British sector just east of Caen. The British held the eastern part of the beachhead and the Americans, controlled the west.
Nebeker:
This was where they used and tested this new system?
Sullivan:
That's right. I was also involved with the operation and maintenance, particularly since the plotting board was new to the Army people.
Nebeker:
How long did you stay with that?
Sullivan:
I'd say about three to four weeks.
Nebeker:
Then you had another assignment and the team continued?
Sullivan:
They stayed. As a matter of fact, I was there, now that I think about it. One morning when I was shaving away, the operators called to me, "Hey, Sullivan! Come here! Look at the PPI!" And there in the PPI was line of moving targets. What were these moving targets? They were the heavy bombers and the medium twin-engine attack bombers setting out to fly 3,000 sorties against the narrow part of the front at Marigny. They just blew a hole right through it. We had had a precursor. One night we'd gone back to battalion headquarters in the jeep. There were about four or five of us piled into the jeep. We were coming back to where the ground-control radar was located. Of course we didn't have any lights on. Not too far ahead we heard this clankety clankety clankety clank. It was a tank column. They damn near ran us over. We drove off in the ditch, and they went by. [Chuckling] We made a few inquiries. The rumor was that the Third Army had landed on the beachhead. That was Patton's bunch. It was a pretty well-kept secret, I think. After that encounter that night they had gotten into position. The bombing opened up the German lines, and the Third Army went through it, down to the south. There was a counterattack at Avranches, and then they turned east and went on — after they did the ? bit and took Paris. We had a ring-side seat because we ranked fairly high from this ground-control bombing bit. I ran over to the radar and started looking at the damned PPI, and I ended up [Chuckling] around midday with a crust of shaving cream all over my head. [Laughter] The break-out then occurred, and just about a week later, I left the beachhead and went back to England.
SCR-584 Training Mission
Sullivan:
Lee Davenport was a major player in the 584 development program from the very beginning. Along with Getting who was perhaps the inventor of modern fire control, he was one of the primary architects. Davenport was at Radiation Lab not very long after Getting joined up. He was one of the founding fathers of the 584 radar. He came over, and he was on the beachhead with us for about a week or so. Then I went back to England with him. When we got back to England, we went around to Anti-aircraft headquarters and got connected with Col. Arthur Warner. He had been at Radiation Lab. Warner was a reserve colonel, and he was called up to active duty. He had left Radiation Lab and had gone to England — or something. At that time he was a member of the Advisory Specialists Group, which was a group of 11 to 15 people who served as advisors to Eisenhower and his staff at Supreme Headquarters. We had dinner with them where they lived out in Richmond Park. This group lived well. To Lee Davenport and myself, he said, "Come on. Let's drive down to the south coast and see what's going on with the buzz bomb show." We drove down along with a few of the other people of the Advisory Specialists Group, including Davenport, Warner and others. We got down there, and it turned out that the heavy anti-aircraft defenses had not been in position all that long, and they were not doing very well. They were suffering from a grave lack of training.
Nebeker:
Were these the Americans troops?
Sullivan:
I'd say they were American and British because the equipment was all pretty new to them.
Nebeker:
They must have gone to some kind of school before operating those devices.
Sullivan:
A lot of them hadn't had very much schooling. Oh, for example, the anti-aircraft battery that I did some work with along with Abajian up north of Lippits Hill, were Army people, fresh from Iceland. But they were operating a completely different equipment. They were operating 268s, which were not very useful. When they got to England, they were given the 584s and minimal instruction. There was no formal school that I know of in England. As a matter of fact, that battery needed a lot of training. That was part of our job.
Anyway, let me get back to the visit with Warner. He was a very canny person. After we got back, maybe we were having a drink, sitting around relaxing, and he says, "Lee, Sullivan, can you go back next week?" Davenport and I both had seats on Air Transport Command back to Cambridge. He looked us in the eye, and he said, "Hey, after seeing that show, can you guys leave?" He said, "How about spending some time down there on the south coast?" Well, we were looking forward to going back. I'd been over there a while. We made a deal with him: That we'd go down there and see what we could do with every anti-aircraft battery on the coast, if he could get us some seats after we got back. He guaranteed us that 24 hours after we finished the job, we would be on an airplane. We went down. There may have been one or two batteries we missed or didn't have any problems, but we did a through job. We spent the better part of a week or two going from battery to battery measuring and determining its performance. If they had a problem, we'd fix it for them. We set up the equipment and the alignments, including getting the computer to play properly with the radar, and getting the guns lined up with the radar. Some of these people were pretty fresh over there. Perhaps a month later, this sounds a little unbelievable those defenses shot down a 100 out of a 104 V-1s. The equipment was good, and the personnel were damned good once they had the benefit of some training.
Nebeker:
How long did you and Davenport spend on that little training trip?
Sullivan:
I'd say, 'round about a couple of weeks.
Nebeker:
Did you then get your seats?
Sullivan:
By God! [Chuckling] You know what they did? Now this again sounds less than creditable. What the hell! Somebody from Supreme Headquarters had called General George, commanding general of Air Transport Command, and made a couple of reservations. The day after we were done with the training trip, we were on our way on another C-454.
Close-Support Bombing in Belgium
Nebeker:
What did you do when you got back to Rad Lab?
Sullivan:
I guess I took a vacation. [Chuckling] In any event, I don't remember getting connected with much. It was a very personal thing, I think. Towards the end of this interlude I remember not being too busy. I think I went off to a party with some of the people that I'd known, before I went overseas. It seemed pretty tame. So I just signed up and went back to Europe. The world was so different that I have trouble describing it. But hell! I just signed up and went back. I guess I got connected again with close-support bombing. By this time the Allied troops had gone from the beachhead all the way across France and were into Belgium. The Ninth Tactical Air Command headquarters had been moved to Verviers in Belgium. I was headquartered there for a while, working on close-support bombing, and then spent some time in the field with one of the radar and control system set-ups, not too far from Malmedy.
Nebeker:
Who did you talk to at Rad Lab to get assigned to field services again?
Sullivan:
I was always a member of Radiation Lab, and I was always a member of Division 8, the fire-control division. So I reported directly to Getting. As a matter of fact, I guess I worked for Getting throughout the whole war.
Nebeker:
You told him, "I'd like to go back"?
Radar Mortar Location
Sullivan:
Yes I told him I wanted to go back. So I went back. I was pretty well finished with any contribution I could make to close-support bombing. Again, Colonel Warner comes into the picture. He was at SHAEF, and I guess he had talked with people at the British Branch of the Radiation Lab at Great Malvern. They'd talked about the mortar-location problem. It turned out that due to mortar fire the ground forces casualties were very high — somewhere between 70 and 85 percent. Consequently, they put a very high priority on mortar location. The British had also taken an interest in it. They had begun to think in terms of using an SCR-584, along with suitable plotting equipment. The British, as I say, played a substantial role in the early conceptual ideas, but they didn't push it heavily at the field level. But they had conducted some demonstrations. It got to be very tiresome to search manually for, say, a V-1 coming in over the Channel with a 50 beam. There had been a so-called sector-scan unit built at Radiation Lab, that would automatically scan. When the operator would see a target, he could stop it. That sector scan could be used to scan out over the lines. If you saw a return you could stop the antenna and go into automatic track, say, on the mortar shell. Then you could track the mortar shell along its trajectory usually up over apogee and also down the descending leg.
For my money the British had the best idea. We were already measuring range, azimuth, and elevation. Now we could plot altitude as a function of ground range. That's complicated because every trace is different. But if you plot altitude, or height, as a function of time, it's a falling body, so then it's a parabola. Depending on the muzzle velocity and the quadrant elevation of the mortar, it just slides up and down on this trace. There was a 3-pen plotter that plotted altitude, azimuth, and range. Then there was a plotting aid. It was a parabolic plotting aid made out of plastic that fit in to the parabola on the trace. Then you could extrapolate back to zero height, the point where the mortar was launched from. Next you'd take the range and azimuth and get the rectangular coordinates and feed that to the field artillery. Finally you could start an artillery barrage on the mortar location.
Then I went to Paris. Actually this program had started in Paris. It had moved from the British Branch in Malvern to an Advanced Service Base, in a building we rented from one of the French electronics companies. It was called Societe Francaise Radioelectrique. I got tagged with finishing off the design and supervising the construction of this mortar-location plotter. When it came time to demonstrate it, we took it out to the 15th Army. The 15th Army was quartered close to Dinant in Belgium. They had set up a 584. We took the plotting equipment out, and we tied it onto the 584. They fired German mortar they had captured — any old mortar would have done — to see how well we were at locating it. On the basis of the demonstration, they decided that they wanted to produce some of these. I was tagged as the project engineer with the French branch of IBM Paris. IBM was given the contract to make these 3-pen plotters in a hurry.
It was getting pretty late in the war. About 15 of them were shipped down to Whitley because they were having quite a time down there. The rest of them were distributed to the troops in Europe. I think the first demonstration to the 15th Army was in March of '45. I can remember it because we were quartered in a chateau. Everybody was pretty gloomy. Roosevelt had died. A week later I came down this great stairway into the lobby on the way to dinner, and it was bedlam. The word had come through that the infantry had crossed the Rhine at Remagen Bridge. Up until then, they had all sorts of plans to slog their way across the river. As you probably well know, the Germans didn't blow up the bridge. We got enough people across. It became one of the greatest concentrations of 584s and anti-aircraft of all time. They just reamed it. It was just a solid field of anti-aircraft. They were even using 584s to search the Rhine surface for landing craft or landing-craft assault boats.
Nebeker:
Did you go up there?
Sullivan:
No, I wasn't in on that at all. I just mentioned it as a reminder. That's an indication of where the war in Europe, at least in Western Europe, had gotten to.
Nebeker:
So the mortar program didn't really reach the field?
Sullivan:
That's right. Not to any extent.
Nebeker:
Do you know how that got initiated?
Sullivan:
I think it was initiated by some Army people.
Nebeker:
U.S. Army people?
Sullivan:
They initiated the program based on their assessment of the damage being done by mortars in the Italian campaign. They had tried acquiring mortar shells with the 584 down in Italy, with some success. When word of that got to the European headquarters the U.S. Army took an active interest in it. Col. Warner at SHAEF talked to the Radiation Lab people at the British Branch. Later at the Advanced Service Base, he described the extent of the threat and the problem. They decided again to mount one of these high-pressure campaigns to get some equipment in the field.
Rad Lab Relationship with Military
Nebeker:
I'm interested in that because we're trying to keep tabs on which of these programs were internally generated within Rad Lab and which ones came from the military.
Sullivan:
I'd say that the close-support bombing application was certainly initiated the tactical bombing people themselves. But there was interaction between the people at Radiation Lab and the Army.
Nebeker:
Yes. They had to know what was being done.
Sullivan:
They had to know that Radiation Lab existed, especially the British Branch. We also had connections with other branches of the Air Force.
Nebeker:
Of course it's Rad Lab people like you and the British Branch who are making known what sorts of things might be done.
Sullivan:
When I came back from Africa the close-support bombing plans were already laid. I was not in on the beginning.
Nebeker:
I meant, generally, to make technical possibilities known to the military.
Sullivan:
Oh, yes. Well, that would be up in the higher reaches of the Radiation Lab or the military. We'd get tagged to get the equipment together and make the demonstrations.
Nebeker:
I know you encountered people who hadn't had much training out there in the field.
Sullivan:
They had some. But in many cases, their training was very sparse. I wouldn't want to malign the Army to the point of suggesting that they sent somebody in without training. Those people were in position, and had operated older equipments. The 584s had been shipped to them overseas. So they'd had virtually no hands-on training, certainly in the States, or at any central school. That was true in Anzio. As a matter of fact, the first two radars that landed on Anzio (if I remember accurately; I wasn't there) got shipped in with the instruction books. They had some fairly talented radar officers that, with the troops, managed to get them to play and to shoot. Getting shot at is a very powerful incentive. [Chuckling] I can't think of a more powerful incentive in the world. If you've got the equipment that's been billed as being able to shoot down these airplanes you are going to figure out how to use it. If you've got it, and you've got the books, you're going to figure out, or try to figure out, how to get it to play.
Nebeker:
What about communication in the other direction? Do you think that Rad Lab people were sufficiently aware of field conditions and needs?
Sullivan:
I think so. First of all the Radiation Lab here in Cambridge was in close contact with the British Branch of the Radiation Lab and later with the Advanced Service Base. They were certainly in close contact with the military here. There was very close contact with the operating people in the European Theater. Radiation Lab had built and designed a large number of other installations including Oboe, the navigational system for bombing for the Midi.
Nebeker:
In your experience was there good communication there?
Sullivan:
Yes. I was never in on it and never involved with it. The British had the first H2S equipment. It certainly wasn't sturdy military quality equipment. It was put together in a hurry to fill a need. Then the H2S was militarized perhaps you would say "improved" by Radiation Lab and sent directly to Europe. The H2S was being installed at Hanscomb, and then they were flying the Atlantic. A few of the Rad Lab guys would go along to keep it running on the ground, and every once in a while they'd go on a mission, which was very interesting. That formed a link. Later on Rad Lab developed and was building the H2X systems. Radiation Lab had associated with it a modest production capability. From the time that they phoned from England that they needed a sector-scan capability for the buzz bomb thing, it was designed, and I around ten of them were shipped and delivered to England, in something like six or seven days. There was a close connection. I'd give the rapport between the military and Radiation Lab very high grades. You were always treated as if you were considered essential. I don't think there were ever any involvements where the interaction wasn't a pleasant one.
"Marco Polo" Orders
Nebeker:
As a civilian out in the field in moving from place to place you didn't have any real difficulties?
Sullivan:
Oh, no. We were the objects of envy on the part of the lower officers. They used to needle us for having so-called Marco Polo orders. Their orders were usually very specific. Captain Such-and-Such will proceed from such-and-such to such-and-such. I had a set of orders at one point that said: "L. J. Sullivan, unarmed civilian accompanying the Armed Forces of the United States, is authorized to travel anywhere in northwest Europe in the pursuit of his duties." So I could go anywhere.
Nebeker:
Those are called "Marco Polo orders"?
Sullivan:
That's right. [Chuckling] That's what they called them. The Army guys called them Marco Polo orders. [Laughter] I had a vehicle; I had a jeep. That's the end of true confessions. [Laughter] Well, let me say this: there were two very useful things to have. One was a pad of blank trip tickets, and the other was a pad of gasoline chits. Sometimes as you traveled around and things changed, you had to be able to move, get gasoline, and so forth. As I say, we were mobile, and we had transportation. The jeep was pretty good. When Leighton came, I had the jeep. Then somebody made a great discovery that there was a whole field full of half-ton Army GI ambulances. The Army decided to stop supporting the half-ton chassis and motor as far as spares and so forth. These vehicles were surplus. It turns out that the Army ambulance is the only Army vehicle that had a heater. Since also had supports for a couple of stretchers you could turn it into a camper. [Laughter] So the first vehicle we latched onto was an ambulance. Of course, we painted out the crosses and so forth. But that was a good deal. [Chuckling] So let's see, where are we now? I don't want to run off here too far.
End of War
Nebeker:
What you've told me about the field operations has been very helpful. I don't think we've covered the end of the war and the end of your Rad Lab experience.
Sullivan:
After I got finished the mortar-location job in Paris and the first production unit was coming off, I came back to the States. Then there was the Pacific war. They'd already started programs at Radiation Lab on mortar location that went beyond using a 584 and the 3-pen plotter that I described, but that would have wide-angle coverage and very rapid extrapolation back to the launch points by using antennas that gave a very wide sector scan angle. One of these consisted of four paraboloids that rotated somewhere around 120 rpm and that switched the beam, the energy, of the output of the transmitter and the receiver, the input to sector sequentially, and it had this 90 degree sector out in front. They'd get 30 scans per second emitted out of it. So we would get 30 looks in this 90 degree sector. I was assigned to working on that.
Nebeker:
Did you work on this assignment under Getting?
Sullivan:
Yes, in the same division with Getting. Then I was also tagged to put into production the same 3-pen plotter that had been manufactured by IBM in Paris. The Research Corporation was making a limited production of maybe 30 to 50 of those 3-pen plotters to go along with 584s. Fairly early in the war there was an interest on the part of the military — some of the people down at the Coast Artillery Board to miniaturize these? I remember this all going on down at Camp Davis. Col. Jimmy McGraw was drawing sketches in the sand as to what this thing might look like. We thought we could take the 584 antenna, cut down the size of the electronics, leave the pulsers, and use pretty much the same control panel. It turned out that you could indeed mount it all in a four-wheel motor generator trailer. There was an M7 35 kw motor generator that was used to run the gun battery. The whole 584 active components were pretty crowded, but you could fit them in there. That was small enough to land on a beach. I don't remember what it weighed, but it was agile enough to be used in a landing. That would have been the 784, I would guess. That would have been the radar that would have been used with this plotting equipment. They were already planning the invasion of Japan. Hitting the beach with a 584 seemed a little bit out of order. That's where the 784s would have come in.
Nebeker:
You worked on that?
Sullivan:
That was being done by Westinghouse. That made the 3-pen plotting arrangement for the mortar location which made the system viable. Then you had a set of equipment, a system you could land on a beach somewhere. At the same time, this other equipment was being developed with the expectation that if the war goes on out there, that sort of equipment might play a role. Radiation Lab was also developing another project to detect mortar location based on a very fancy scanner, the so-called Foster scanner. Its coming to fruition was pretty far down the road. Sometime, very early in that process, I signed up to go to the Pacific. I had gathered a moderate amount of experience with the mortar-location business in Europe (of course it didn't take too much to become an expert during the war), so it seemed natural for me to sign up and go off with the equipment to the Pacific.
Nebeker:
Did you do that?
Sullivan:
No! We were pretty well along in the production of these plotters. I was working away with this fellow named Krohn on this 4-parabola thing. It got to be known as the "whirling dervish." It was a frightening thing. It went around at 120 rpm. One day we were at one of the old wooden buildings over there in Cambridge, and just a titter went through the everybody in the place. We'd dropped an atomic weapon on Hiroshima. That was it. Everybody knew that within 10 or 15 minutes, I think, within an area of a mile or two that, hell! The war is over.
Nebeker:
What did you do at the end of the war, then?
Sullivan:
When we heard the news, we just took off and had ourselves a blast. We celebrated the end of it all. Oh, then they gathered us all in the Great Court over there, and DuBridge got up and said: "Fellows, I would suggest that you seek employment elsewhere. Radiation Laboratory will close in one month." Everyone left except for the guys that stayed around to write the books. Then I took a job down in New York with the L.H. Terpening Company redesigning electronic and radar equipment. I stayed there a couple of years. After that I went to the Applied Physics Lab at Johns Hopkins. I ended up at Johns Hopkins leading the group studying the tracking and guidance radars for the Terrier and the Telos missiles. I worked on the first ship to bear anti-aircraft missiles. The Terrier missile was a beam rider, and the Telos was a big homing missile.
Secrecy of Rad Lab
Nebeker:
It's obvious that your Rad Lab experience was valuable in your subsequent career.
Sullivan:
Oh, I'd say almost to a semi-infinite degree. [Chuckling] The thing was that during all of the whole period at Radiation Lab, virtually everything was secret. As a matter of fact, the word "radar" was secret. It was well kept as far as I know.
Nebeker:
Is that right!
Sullivan:
Oh, yes. It was a no-no to mention "radar." We were very thoroughly instructed on not ever mentioning even the word. As a matter of fact, there were all sorts of subterfuges. The production people at Chrysler who made the antennas the parabaloid were told that they were making just a new kind of searchlight. After they delivered it, it would have the searchlight system mounted on it. This was all kept secret. Also, there were no publications. Everything was virtually secret. Everything had to be cleared before it was released into the general community. I only remember one book written by Don Fink that was sort of a summary on radar. That was kept in the safe. There was just one copy in the whole division that I know of. You read it in a sitting, and that was it. I don't remember reading anything in the way of theory or the components developments of Radiation Lab. The reason I'm belaboring that is that when the people at Radiation Lab went off into the world, they carried the lore in their heads.
Nebeker:
That was about the only place it was.
Sullivan:
That's right. We had to play catch-up. It was about two years before the books came out. I think it's fair and accurate in saying that the war was Homeric. I mean, it was passed on by word of mouth. These people scattered around the country working in the new electronics business. Some of them went out as messiahs. They were going to bring these new technologies to some of these backward industries. Quite often the backward industries would devour them. Some of them were pretty well set in their ways.
Postwar Career
Nebeker:
What about some of your personal acquaintances made at Rad Lab? Did they play a part in your subsequent career?
Sullivan:
Yes, a few of them played a very important part in my career. I would say George Harris was quite significant. Perhaps I didn't mention George often enough at the very beginning. He was also in the XT-1 program early in the game. I'd gone through MIT with him and had known him after MIT while I was in the physics department. At some point he had gone to work in Getting's division at Radiation Lab. I think he might have played some role in my going to Radiation Lab. I don't quite know. My work with Professor George Harvey and George Harris probably got me the position. I worked with him on some jobs overseas. I did a little work with him at the Applied Physics Lab when I was at the L.H. Terpening Company. As a matter of fact, he was instrumental in my going to the Applied Physics Lab. He certainly played a substantial role in my going into applied physics (at least at Radiation Lab). He essentially hired me into the Applied Physics Lab. I stayed there from '48, to '53. I was there about five years.
Nebeker:
Then you came to Lincoln?
Sullivan:
Then I came to Lincoln, and I worked on a pulsed-operator. It was a fire-control application. During that era the emphasis was on defending the U.S. against strategic bombing. So that there were long-range systems being developed there: ground-to-air interceptors, all of the search radar, ground-control radar, and the SAGE system, the automatic interceptor control. At the same time there was a concern about low-altitude aircraft. This radar that I worked on was part of an overall porcupine system which, was an undirected rocket fire system. The system didn't prosper. It didn't go anywhere. But the radar was successful. It was one of the first very high TRF, high-resolution Doppler radars that formed a coherent system.
The first job I got when I went to work there was on an old shipboard antenna. They had a very experimental version of this pulsed Doppler radar. They had this antenna that had come off a ship, and it was falling apart. Then they latched onto one of these 784s, SCR-784s. When I joined that group, they were standing around sort of looking at it, wondering where to start. It just so happened that I knew that system inside out. I got the antenna to play in short order. Then another fellow and I were given the job of making a mobile version. This first experimental version was on the roof out in Cambridge, as a matter of fact. Then our assignment was to incorporate a new mobile unit into a trailer, which we did. Then by this time we'd moved the whole operation out to the Lincoln Labs operation in Lexington. They lifted the trailer on to the roof. We did a lot of development and testing with aircraft operating out of Hanscomb. The real emphasis was to develop a system that had an extremely high visibility. In other words, it would be able to detect a small target against all of the clutter, including the ground and the weather. It was quite successful. Finally, when we finished off that, we had a visibility of 70 d.b. As a matter of fact, we'd gotten to the point where we were running out of our ability to find clutter. We spent a lot of time honing that radar.
Then what happened? At the end of that program, we gave the radar to what is now the Air Force Geological Research Lab, at that time known as the Air Force Cambridge Research Lab. They used it for meteorological research. It was useful for viewing and mapping what was going on inside a thunderstorm. By virtue of the Doppler it could make a velocity map, and it gave an excellent presentation or display of the turbulence.
Nebeker:
Had you noticed radar images of thunderstorms during World War II?
Sullivan:
Oh, yes. You could see rainstorms with S-band. I don't remember much in the way of thunderstorms, but you could see rainstorms. You could use the radar for finding clear patches. You could tell what the weather was. It was more of an occasional stunt on the part of a single set of people. I don't remember any coordinated effort in the development of weather radars.
Many Uses of XT-1
Nebeker:
I've reached about the end of my questions. Is there anything you'd like to say about your Rad Lab experience that I haven't asked about?
Sullivan:
I think I share the feeling with a lot of Rad Lab people: It was a great period of one's life. I think at the end of the five year stint at Radiation Lab, I certainly had the feeling that I had lived a whole lifetime.
Nebeker:
It's amazing how many places you were, and what different things you worked on.
Sullivan:
Certainly you moved around. You got to move around the world at a great rate. Wherever there was a problem, wherever there was a job, you just went on military orders. I wouldn't want to go back and backtrack. I think I didn't really do much justice to the early prelude in this country. I think it's in the books. The XT-1 traveled around the countryside doing a number of different kinds of tests. I think some of these were important. First of all, we went to Aberdeen. We were headed for Langley Field. Then the National Advisory Committee (the old NACA) wanted to do some aircraft testing. They wanted us to bring the radar down there to track aircraft flight path and also measure aircraft velocity. We did some work on the SB2C dive bomber and also on the P51. On the way down to Langley Field, we stopped off at the Aberdeen Proving Ground and set up to track 90 mm anti-aircraft shells. We could easily track these 90 mm anti-aircraft shells.
Nebeker:
What year was this?
Sullivan:
It was somewhere in the first quarter or first third of '43. Then somebody got the idea to measure the velocity. It was the first time they had a means of continuously measuring the velocity of a shell. Before that they would fire magnetized shells through two enormous solenoids on these big gantries. But that way you could only get the average velocity. Using our equipment we could track and measure the velocity. Then they suggested, to set up a pair of coils. We would fire some 90 mm rounds through them, the radar would track them, and we could compare results. The agreement wasn't all that good. The field commanders thought there were some problems with the 90 mm firing tables. After we compared the data taken with the radar and the data from those coils, 90 mm firing tables all over the world every ballistic cam, every mechanical computer, the old M7 computer, was wrong. That caused a bit of upset. Fortunately the M9 computer, the electronic computer, was coming into production. There was time to catch it before it went out into the field. They had a ballistic potentiometer that had to be derived from the firing tables. That was one interesting task.
Nebeker:
That was very, very important, obviously. Do you know the source of the previous error?
Sullivan:
Yes. The trajectory work was all done on the differential analyzer, which was a mechanical computer with a ball and disk and gears and wheels. Somebody had accidentally reversed two gears. The ratio is supposed to be .9. It turns out that they got it backwards, and it was 1.1. Well, that's an exaggeration. It was more subtle than that. But it was enough to be more than a nuisance.
Nebeker:
So in a sense it was a programming error in the set-up.
Sullivan:
That's right. It was a programming error, only it was mechanical. [Chuckling]
Nebeker:
Right.
Sullivan:
And I think that's in the literature, as a matter of fact. I think Getting mentions it in his Decisions for Democracy. Perhaps Guerlac makes some mention of it. Another guy and I made all the measurements and reduced the data. We left Aberdeen not having convinced them that they had a problem. That was like questioning the sacred text. Two or three weeks later I got a call from the assistant director at Aberdeen who was responsible for all of this. He said: "It pains us, but it's going to make you happy, Sullivan. We found a mistake in the firing tables." Then we went down and did the job at NACA. I guess the Navy had heard of it. Then we went back to Cambridge, but then we got another assignment to go down to Cherry Point, North Carolina, to the Marine Air Station. The Navy wanted us to track an F-6F fighter, in a terminal velocity die. It was red-lined at a speed that they were beginning to push and almost exceed in combat in the Pacific. They wanted to get an accurate trajectory, a flight path and an accurate velocity profile.
The problem with the velocity was that in the usual airspeed indictor, you had a static tube and a dynamic tube that measured static pressure and dynamic pressure. If you were in a steep dive, the static pressure was not right. It couldn't follow fast enough. The time constant was too slow. So they couldn't get decent measurements of a velocity. We went out and set up out on the coast around Fort Macon in North Carolina, and the Navy flew their F-6F with a radio control system in it, ground from 30,000 feet. We tracked it, got the trajectory, the flight path and the velocity for them. Then as a result of that, the Navy wrote to the Radiation Lab and said, "We won't ever test another aircraft again without having radar coverage." If there was any glitch in their recording or their observations their whole thing was lost. It was just a waste. So I think they made good their boast. There were two other experimental models that were being built, the XT-1As. The Navy was given one of those for this flight testing. The Navy assigned a crew right from the very beginning, and I went down with them to Cherry Point Naval Air Station, and we carried out that test.
Nebeker:
It's interesting how many different uses there are for radar now.
Sullivan:
That's right. It was serendipitous that they found it. From then on it was given the task of tracking just about anything that flew around in the air. Then it ended used in space on a big enough target.
Nebeker:
Well, thank you very much.
