Peenemünde Interviews Project: Konrad D. Dannenberg 11/7/1989 (Tape 1 of 2) A
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MICHAEL NEUFELD: OK, this is, uhh, interview with Konrad Dannenberg on November 7, 1989, in Huntsville, Alabama; interview by Michael Neufeld --
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-- um, OK, I want to start with the, we always start these interviews with a general biographical background information -- could you give your birth date, birth place, occupation of your parents, and so forth, (that) kind of information --
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KONRAD DANNENBERG: Well I was born in Weißenfels, which is just south of Leipzig, which is now pretty much in the news these days. So, today, of course, it's eastern Germany, in those days, of course, there was just one Germany.
MICHAEL NEUFELD: It was Saxony --
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KONRAD DANNENBERG: Yeah -- My dad was in the army and he moved pretty soon after my birth, on the 5th of August 1912, he moved pretty soon to Hanover and I really spent most of my youth years in Hanover. I went to school there, I visited the university in Hanover --
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-- and in the late 1920s we had some rocket tests taking place in the vicinity of Hanover. You may have heard about Burgwedel where some Opel cars were being tested with -- [[crosstalk]] --
MICHAEL NEUFELD: --on the rail tracks --
KONRAD DANNENBERG: -- solid-propellant motors strapped to it? And we had a suitable racetrack, so they came to Hanover, and I participated in these tests. I understand they made three of them, and I seem to recall that I saw two of them --
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-- and that interested me and some other people I worked with, some of my comrades at that time, to really become interested in rocketry. So I started relatively early -- in fact, we were thinking about rocketry already before we saw these tests, and these tests just provided some additional initiative, and uh --
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MICHAEL NEUFELD: I wanted to ask you, is your father an army officer, at the -- ?
KONRAD DANNENBERG: Right.
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MICHAEL NEUFELD: And uh, was he killed in the First World War? [[crosstalk]] He was fortunate --
KONRAD DANNENBERG: No, no, he survived and --
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-- of course he stayed then in Hanover, he was during the war already in Hanover, my mother was there. I had a sister; she died during the war.
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And he worked for the post office.
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He was on long-term duty in the army and the German army then normally provided employment in the post office, the rails, or some federally-run organizations. So he was working for the post office when I grew up. And uh --
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MICHAEL NEUFELD: He didn't continue on in the Reichswehr.
KONRAD DANNENBERG: Right, he did not.
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And, uh, after I had seen these tests, of course we became quite interested in rocketry. And we had our own little rocket field in Hanover. It was not quite as well known as the one in Berlin where von Braun worked, but you probably know there were many of these amateur rocket societies.
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Apparently people after World War I at that time, they were interested to look a little bit broader ahead, and there was not too much going on in Germany, we had the big inflation even, during those years.
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And so people, I think in general became quite interested in Raumfahrt, in space exploration -- we had the movie 'Die Frau im Mond' in the late 20s or early 30s -- must have been around that time.
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MICHAEL NEUFELD: It was the end of 1929.
KONRAD DANNENBERG: Ja, and that all enthused us, so --
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-- when I finally heard about Peenemünde - I learned about Peenemünde from a fellow I'd been working with, Püllenberg, Albert Püllenberg, who's also still living in Germany today. He lives in the Ulm area.
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And he was really the head, so to speak, of our rocket activities in Hanover. He was the most active one. He later on even married a girl who had a -- kind of a shop that he could really build on a bigger scale, rockets, launch facilities, and things like that.
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He did not decide to come to this country after the war, he decided to stay over there. And he took even after the war his own rocket activities up again.
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And I learned through him about Peenemünde, of course he couldn't tell me 'we build rockets here,' --
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-- that was top secret, so he indicated in his letter to me between the lines: 'here is some work going on, which I'm sure you would like. And why don't you try to get away from whatever you are doing now and come and join me here in' -- and I think the name at that time was Karlshagen or some place close by where most of the people lived.
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And when the war started - I had graduated in the meantime, I went in Hanover to school, as I mentioned earlier.
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And maybe one thing is even of interest - I went purposefully into the area of diesel fuel combustion, diesel fuel injection because we had learned in Hanover that that was at that time one of the big problems -
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How do you really properly introduce your propellants, into your rocket chamber? How do you mix them properly? And what do you have to do in order to get good combustion?
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So in order to learn more about it, I started diesel fuel injection - of course no one taught anything about rocketry, but that was the closest field to it.
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And when the war ended, I was a volunteer in the German army - though I initially was drafted in the German Army - but they sent me to a horse-drawn anti-tank battalion and that was for me enough reason that I finally got out of the army.
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I could use the fact that I as a technical man with a Dipl-Ing. in engineering, that I shouldn't serve in a horse-drawn company and so I managed to get out of the army.
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And I worked at that time before, just before the war, for the VDO - they build tachometers. You, if you, drive a Mercedes you probably have a VDO tachometer in your Mercedes.
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Of course during the war, they built all kind of war-time instruments - mostly radar-type or communication-type instruments.
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And they got me out of the army, they justified it with, they needing me.
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And once I was back at the VDO, I didn't have too much of a problem to get from the VDO then transferred to Peenemünde.
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So that's the way I finally came to Peenemünde in the summer of '40. Early summer '40.
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MICHAEL NEUFELD: Can I, uh, I want to ask you a number of detailed questions before we even get to that stage --
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When your experiments with - You participated in these rail car experiments in what would have been -- [[cross talk]] -- 1928.
KONRAD DANNENBERG: Well I watched them, I didn't participate.
MICHAEL NEUFELD: OK. You were there.
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That was Opel, was it?
KONRAD DANNENBERG: That was Opel, ja.
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MICHAEL NEUFELD: That wasn't Valier - 'cause I know that they had gone their separate ways, --
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-- just after the rocket car business -
KONRAD DANNENBERG: Valier had also been in town. He had given an inspiring talk. He was a pretty good talker. You probably heard about him, ja?
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MICHAEL NEUFELD: I've written an article about him --
KONRAD DANNENBERG: And he was a little bit the von Braun type, ja? He could go to the public. He could talk to them. He could convince them.
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And he did a lot of work, of course, ja? But these tests, you are right, they were done by Opel.
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MICHAEL NEUFELD: When did you begin working with Alfred Püllenberg -- in that little rocket group --
KONRAD DANNENBERG: Well that must have been in the late 20s.
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It was before we saw the railroad tests and they were, I think, in '28, '28 possibly '29.
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And we had started to work on our rockets before that, but that really gave us some additional new spirit again.
MICHAEL NEUFELD: Really?
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KONRAD DANNENBERG: Of course, we didn't have any real funds, we had to spend our pocket money. And we started out with solids - so we bought solids. You could buy them in Germany in those days.
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Fireworks rockets. We took them apart, we cut them open, built them in bigger rockets, and that was really the beginning of the work.
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And then we finally became aware of Oberth's book. I had also read already a relatively early Goddard's book - how to 'Reach Greater Altitudes by Means of Rockets'.
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And we decided that, yes, the right way to go was really to use liquids. So we switched relatively early in the '27 - '28 time period to the use of liquids.
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And we were fortunate enough - I was living in Hanover. Hanover was a fairly large city and we had an air liquefaction plant in Hanover. And separating air you can easily make liquid oxygen.
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And through a professor at the university, an aeronautics professor, Pröll, we got permission to use some of their liquid oxygen. And to use liquid oxygen as an oxidizer.
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MICHAEL NEUFELD: This was 'proll' as P R O umlaut -- ?
KONRAD DANNENBERG: P R O umlaut, double L.
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MICHAEL NEUFELD: Double L -- okay.
KONRAD DANNENBERG: And he is dead now. He was already an old man at that time. So he is not alive anymore. But he wrote a number of books and he was interested in rocketry probably even from the view point of application to airplanes.
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You probably know, right after World War I, Germany was not allowed to build powered airplanes. So people strapped solid propellants, and later on liquid propellants, onto sail planes to get up into the air.
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That was one method - there were other methods to get up into the air.
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And actually, in Hanover, we had a contract from one of these sail plane people, Espenlaub, to build a rocket for him - a liquid propelled rocket for him - and to eventually deliver it. But we had so many problems, we never came to the point of delivery.
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MICHAEL NEUFELD: Yeah - This, all of this, sounds very familiar. You see, I've written an article about that period in the late 20s.
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And I know that - the sail plane idea really took off after the rocket car, Valier, and so forth, in 1928, in April '28.
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So, ah, but you-- You're very sure that you and Alfred Püllenberg and - anybody else in that group? - started before you ever even heard of the rocket cars and so forth?
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KONRAD DANNENBERG: Right, that came later. I'm pretty sure about that. We had been working on it before that.
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MICHAEL NEUFELD: Because I - I don't know of any other private rocket experiments that were going at that time. So if that's true, you would be, maybe, the first.
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You know, Raketenflugplatz didn't start 'til 1930.
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So, that I don't know of any other groups starting so early --
KONRAD DANNENBERG: Well, were there not other activities going on?
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MICHAEL NEUFELD: I don't know of any private rocket groups. Nobody has mentioned it.
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Winkler really, you know, only started working with this right around '27, '28, as well.
KONRAD DANNENBERG: Ja, I think we started at about the same time. And we had heard about Winkler, we didn't meet him at that time.
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MICHAEL NEUFELD: Were you a member of the Verein für Raumschiffahrt?
KONRAD DANNENBERG: We had our own - GEFRA (Gesellschaft für Raketenforschung). And that was a Hanover group.
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MICHAEL NEUFELD: So you didn't feel it was necessary to join the VfR, and get Die Rakete, the journal?
KONRAD DANNENBERG: Well it also was too far away, ja?
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Normally I wouldn't go to Berlin, so normally we wouldn't really have any contact with the people. We knew that they had a club, similar to our club.
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MICHAEL NEUFELD: Yeah, of course that was later. I was thinking about the Die Rakete, the journal -- you didn't see that journal, huh?
KONRAD DANNENBERG: Yeah, I hadn't even thought of it that our activities may have been the very early ones
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MICHAEL NEUFELD: Yeah, because I know the Raketenflugplatz really only starts in late 1930. Of course Winkler was experimenting. I don't know if he even fired up a rocket engine before 1929 or so, I don't think, even on the ground tests. You know, he started working only after he became involved with the VfR and Die Rakete and so forth. So that would make you very, very early.
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KONRAD DANNENBERG: Well, as I told you earlier, I'm a little bit poor with remembering specific dates. I mentioned Püllenberg earlier. He's still living in Germany. Maybe once you are over there again you might want to talk with him, if he's still alive. He's in pretty poor health, and also his memory is not quite as good any more, but he might even send us some documents.
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We published documents. We gave talks at that time. That was one way of raising money, to give a talk, to invite people to the launchings, to pass the hat around, to get a few extra dollars, and this was really all the money we had, and our own spending money, which was also very short, of course.
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MICHAEL NEUFELD: You went to a Gymnasium?
KONRAD DANNENBERG: No, I was in the Oberrealschule, which taught only English and French, no Latin and no Greek.
MICHAEL NEUFELD: And more science?
KONRAD DANNENBERG: And more science, physics and things like that.
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MICHAEL NEUFELD: So you started with the University of Hanover when, in 1931?
Konrad Danneberg: In, er, 31. And that's when I really stopped my rocket activities, ja? So I'm pretty sure it must have been before that time, because I didn't do any major work at that time. Püllenberg ever once in a while tried to involve me, but being a student, you are so busy with new things that I really didn't have the time.
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And I also served at that time one year in the army, so that must have been from 32 to 33, I would say. I think it was still before Hitler took over, so it must have been 32, and er, my dad wanted me to become a teacher, and I was not interested in teaching at all, so I was really not too hot about it, and that's why I left the university to have a year to think about it, and after I came back in 33 then I really went in the technical fields.
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MICHAEL NEUFELD: Were you in the Technische Hochschule?
Konrad Dannenberg: Ja.
MICHAEL NEUFELD: The first year as well?
Konrad Dannenberg: Both times. It was at the same university.
MICHAEL NEUFELD: So you were in the Technische Hochschule Hanover --
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Konrad Dannenberg: Right.
MICHAEL NEUFELD: From 31 to 32. Then you were out one year 32, 33, [[crosstalk][ and then you started again--
Konrad Dannenberg: Right.
MICHAEL NEUFELD: And then I started again and then I went into strictly technical fields. My dad had consented in the meantime, "Well, if you really don't like teaching..." and also teaching jobs were not that plentiful any more.
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When I initially went to school we had still a lot of unemployment, ja. 31 was very bad over there. [[crosstalk]]
MICHAEL NEUFELD: The peak of the, the peak of the chaos-- [[crosstalk]]
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Konrad Dannenberg: And there was practically no job you really could get. That was really the main reason for me to go to the university: I couldn't find a job, and then my dad felt if you are a teacher, you, once you are hired you have a lifetime position.
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So that's why he wanted me to go into that field. But as I said I wasn't too hot about it, and I would have been a high school teacher, I would have had to know how to play the violin, you had to take music, that was one of the subjects you had to dig into, and I really didn't like that at all.
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MICHAEL NEUFELD: So what was your er, what kind of engineering did you er, [[crosstalk]] major in--
Konrad Dannenberg: Well of course the first few years we are basic engineering, ja, and only the last few years I then concentrated on combustion engineering for diesel engines, and I was even after I had graduated for about a year maybe two years, an assistant to a Professor Neumann in Hanover, and he was running the Verbrennungskraftmaschine Institute.
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And I was an assistant to him and that was already just before the war, it was in 38--
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MICHAEL NEUFELD: Ok so when did you--just to pin this down--you went back in 33; when did you finish again? [[crosstalk]]
Konrad Dannenberg: 36 or 37. Probably 36, and then I stayed for a good year, a year and a half, in the Institute as an assistant to Neumann, and our specific task there with a group of students with whom I worked was to convert one of our old automobiles--we had a 1905 Daimler, not Daimler-Benz, just Daimler, Mr. Daimler still did his own work at that time-- and we converted that to Flüssiggas, to propane gas--
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MICHAEL NEUFELD: Ok, liquid gas.
Konrad Dannenberg: Yeah, we had gas, relatively small oil well close to Hanover in Nienburg, and besides the oil they also recovered some natural gas--
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MICHAEL NEUFELD: The name of the place was Nienburg?
Konrad Dannenberg: Nienburg.
MICHAEL NEUFELD: N-I-E-N-B-U-R-G?
Konrad Dannenberg: Right.
MICHAEL NEUFELD: Ok I think I've heard of it [[Crosstalk]]
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Konrad Dannenberg: And there was a factory which made on the one side gasoline from the oil, and also from the byproducts they got some propane and filled it in propane bottles.
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And it became clear already that we wouldn't have enough gasoline during the war, so there was quite a drive on from the Hitler regime at that time to go into those fields, and that's what we did, and, well I worked on it until the project was finished, and then I left and went to the VDO as I mentioned earlier: [[spelling in German]] Fow, day oh. [[Crosstalk]] the Komeda outfit.
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MICHAEL NEUFELD: And that was in Hanover?
Konrad Dannenberg: That was in early 39. I left Hanover in early 39 and went for about half a year to the VDO, so I was not there very long and then when the war started-- [[Crosstalk]]
MICHAEL NEUFELD: Where was the VDO located?
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Konrad Dannenberg: That was in Frankfurt, Frankfurt, Main, and when the war started I was then pretty soon drafted into the army because I was serving in military reserve duty, and of course all these people were immediately called and that must have been late August, 39. And from then on I was for about a year in the army, and then early next summer I finally got my transfer to Peenemünde.
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MICHAEL NEUFELD: So did you serve in a campaign, in that 39, 40 did you serve [[Crosstalk]] in Poland or France--? [[Crosstalk]]
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Konrad Dannenberg: We walked on foot through all of France. We started way down south, the south of Strasburg, even at the Swiss border, really, and then we walked behind the Maginot line almost all the way to Dunkirk, but Dunkirk had fallen or the Allied forces had gone back over the channel, ja, so we never made it all the way to Dunkirk, but we stopped and there we turned around and walked all the way back again to Strasburg, and in Strasburg we then finally went back over the Rhine and we were stationed in Freiburg, Baden.
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MICHAEL NEUFELD: So you would have been transferred just after the successful conclusion of the French campaign--[[Crosstalk]]
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Konrad Dannenberg: Right, right, right after that-- [[Crosstalk]]
MICHAEL NEUFELD: French and Low Countries-- [[Crosstalk]]
Konrad Dannenberg: and my company later on was transferred to Russia, but I never went with them to Russia, so before that happened I got out of the army.
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I worked for just a little while for just a few months for the VDO again, and then I got dienstverpflichtet.
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You probably have heard that term: dienstverpflichtet already. So Peenemünde really called me, ja.
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And that's why I said it was easy. Peenemünde had a fairly good priority at that time so they could call on people they knew were interested in that field and so it was really called dienstverpflichtet to Peenemünde.
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MICHAEL NEUFELD: Now 'cause I raised the question I guess I get this straight: as far as Püllenberg was concerned he wrote you then, before the war--? [[Crosstalk]]
Konrad Dannenberg: Well we had, we had continued correspondence. I had known him quite well. His dad worked also for the postal office, so our dads were fairly closely acquainted, and due to that connection I had also correspondence with him, not very frequently, maybe for Christmas and Easter, or so, but we stayed in contact, and that's the way I found out about the activities in Peenemünde.
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MICHAEL NEUFELD: When did you sort of figure out what was going on up there? That there was something going on? [[Crosstalk]]
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Konrad Dannenberg: Well of course, after I had heard about it I seemed to recall I made first a visit, and had to introduce myself. I met Walter Thiel at that time, Thiel is the number two man after von Braun before the bomb raid; he was killed in the bomb raid,
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and he apparently was interested, and he then dienstverpflichtet me. He then called me to Peenemünde.
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MICHAEL NEUFELD: So you would have visited the first time and then gone away again that one time that-- [[Crosstalk]]
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Konrad Dannenberg: I think I went back home again and then I finally got my final assignment. And of course at that time when I was up there then I learned basically what they were doing.
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MICHAEL NEUFELD: From ... In the past all you had known was that Püllenberg was doing something probably regarding rockets.
Konrad Dannenberg: Right,right [[Crosstalk]]
Michael Neufeld: You didn't know what and did you even know approximately where he was? Or was that secret too?
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Konrad Dannenberg: No, no, I had lost the contact with him until he wrote to me again and announced that this kind of work was going on there. Interesting work for me was going on there.
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MICHAEL NEUFELD: That would have been about 1940, already then.
Konrad Dannenberg: That probably was early in 1940.
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MICHAEL NEUFELD: So at, you got called then through that connection and through your going up there and meeting with them you got called to Peenemünde
Konrad Dannenberg: Right.
Michael Neufeld: And in late 1940? Something like that.
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Konrad Dannenberg: No, that was early summer of 1940, so I would say June, July, so relatively early in summer.
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MICHAEL NEUFELD: Ok. So that would have been almost at the very end of the campaign then, right? The French campaign.
Konrad Dannenberg: Was the French campaign was that not even in 38?
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MICHAEL NEUFELD: No, the French campaign was just over, in, June 1940.
Konrad Dannenberg: June 1940. Then it was just at the end of the French campaign.
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MICHAEL NEUFELD: Ok. So you probably went when you just after got back from that campaign.
Konrad Dannenberg: Right.
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Michael Neufeld: You got called into, you were probably assigned to the Versuchskommando Nord, right, the Army unit. [[Crosstalk]]
Konrad Dannenberg: I guess so, ja.
Michael Neufeld: I mean, you don't, do you remember that name of that unit--
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Konrad Dannenberg: Well, Versuchskommando Nord was really a military unit. It was not in existence at the time when I got up there. Military people were only assigned to Peenemünde in 42 or so. So in 40 it was strictly, there were some army people: Dornberger was there and a few other captains with him, but the main workforce, were really civilians, like I: dienstverpflichtet.
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MICHAEL NEUFELD: So you were, officially, so you were not then assigned as an army person-- [[Crosstalk]]
Konrad Dannenberg: No, I had left the army.
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I was civilian [[Crosstalk]] I was civilian. Right.
MICHAEL NEUFELD: So you had been effectively released from the army, put back on reserve, you were put back on army reserve,
00:24:01.000 --> 00:24:16.000
and you were dienstverpflichtet, sent to Peenemünde, then in the summer of 40. I just want to get this straight. See, I'm not even sure about Versuchskommando Nord, when it started, when it existed --
00:24:16.000 --> 00:24:39.000
Konrad Dannenberg: It must have been two years or so later. At that time Hitler had declared the A-4, as we called it in those days, of high priority, and then we could draw on army personnel. And we even, there was even an autoroute to the army to assign all technically qualified people to Peenemünde.
00:24:39.000 --> 00:24:45.000
But that happened only later. That was at the time after the A-4 had been declared again of high priority.
00:24:45.000 --> 00:24:55.000
You have probably heard already: at some time it was on then it was off again and then it was on again so that kept on changing. And in the beginning it was strictly an army project.
00:24:55.000 --> 00:25:08.000
Really the party had nothing to do with it; it was strictly run by the army, and that's why of course initially we got army people. Later on we got also a lot of air force people. After the air force got also involved with the Wasserfall particularly.
00:25:08.000 --> 00:25:19.000
But in the early years it was strictly an army activity, and, as I said, at the time when I got there, it was strictly a civilian activity.
00:25:19.000 --> 00:25:32.000
And er --
Michael Neufeld: You didn't see the army officer, I mean of course there was an old group of people from Heereswaffenamt who had come through Dornberger, Zanssen--[[Crosstalk]]
00:25:32.000 --> 00:25:42.000
Konrad Dannenberg: Some of them, a few of them were there but a relatively small group, and they did mostly managerial work: they administered the whole organization. They were not technical people.
00:25:42.000 --> 00:25:50.000
I would even say Dornberger was probably the only technical man. You probably know he had an engineering degree.
00:25:50.000 --> 00:25:53.000
Michael Neufeld: I think Zanssen was an engineer as well.
Konrad Dannenberg: Zanssen could have been one too. Ja.
00:25:53.000 --> 00:26:02.000
But all the others were regular army officers, and so they didn't really participate in the development as such. They administered.
00:26:02.000 --> 00:26:18.000
Michael Neufeld: They were basically in a base commander office at that level. So you were then taken into Thiel's group. He must have just actually have come from Kummersdorf not very long before-- [[Crosstalk]]
00:26:18.000 --> 00:26:33.000
Konrad Dannenberg: Ja, he was still fairly new, I seem to recall, and probably that's why he was interested to hire additional people, ja? That's why he was interested for me to come up after I talked to him and told him I had a certain background in combustion engineering, and he was looking for people like that.
00:26:33.000 --> 00:26:42.000
. And for that reason of course he put me after I was up there right away on the job to develop the injection units of the A-4 engine.
00:26:42.000 --> 00:27:02.000
You probably have seen it, the way we have it out there. We have 18 individual elements, Töpfe, as we called it, that initially mixed the propellants and then of course the 18 elements mix again in the main chamber. And my first job was to work on these individual elements,
00:27:02.000 --> 00:27:20.000
and for that purpose we even had a smaller engine, a 1.4 tonne engine. Each and every one of these elements has 1.4 tonne tube, and we did all the basic, the initial research on the smaller unit, the one four tonne unit. And I also worked on the one tonne unit which was strapped to airplanes,
00:27:20.000 --> 00:27:25.000
JATO: jet assisted take off.
Michael Neufeld: Starthilfe.
00:27:25.000 --> 00:27:35.000
Konrad Dannenberg: Ja, and that was a very similar unit; it had also a somewhat conical head, then a combustion chamber about that long, and-- [[Crosstalk]]
00:27:35.000 --> 00:27:46.000
Michael Neufeld: Was that about a foot long?
Konrad Dannenberg: Ja, and then a nozzle, a rocket throat area which gave us a lot of problems, so I spent also quite some time on solving all these burn-through problems,
00:27:46.000 --> 00:27:54.000
and they normally burn through in the throat area where you have of course very high velocity and still fairly high temperatures.
00:27:54.000 --> 00:28:14.000
Michael Neufeld: Er, let me tackle one of these things at a time. When you came the Starthilfe--of course this is one of the things I have to figure out--that Starthilfe project, JATO project, that was still going, was it?
Konrad Dannenberg: Right.Right.
Michael Neufeld: That was just at the end of development or you still were finding problems--[[Crosstalk]]
00:28:14.000 --> 00:28:33.000
Konrad Dannenberg: Well we built already the ready units, and they were being used, they were being flown, for some reason or other I never really quite understood why--maybe the reason was these units were developed by the army. And they were then turned over to the air force, and the air force apparently was not too impressed with them.
00:28:33.000 --> 00:28:48.000
So they really, I think to my knowledge they never got really into major operational use. Some of them were used, there were certainly some demonstration flights, some of which I saw--
Michael Neufeld: At Peenemünde West
Konrad Dannenberg: At Peenemünde, Peenumünde West, ja-- [[Crosstalk]]
00:28:48.000 --> 00:29:00.000
Michael Neufeld: At the air force Platz, huh? [[Crosstalk]] That was the test, so the test at Peenemünde West was certainly later than what, after you got there--[[Crosstalk]]
Konrad Dannenberg: Right, they were later, after the unit had been more or less developed.
00:29:00.000 --> 00:29:07.000
Michael Neufeld: So that would have been later in 1940 probably--
Konrad Dannenberg: Later 40 and possibly even 41, possibly even into 42.
00:29:07.000 --> 00:29:21.000
Michael Neufeld: I know that the fact they decided to go over to a hydrogen peroxide one that was developed by Walter --[[Crosstalk]]
00:29:21.000 --> 00:29:30.000
Konrad Dannenberg: [[Crosstalk]] That could be one of the reasons. I hadn't even thought of that. You may have a point there: they are simpler. They are not quite as efficient, but you drop them anyway, ja, so if they are a little bit heavier, it's not all that critical.
00:29:30.000 --> 00:29:40.000
Michael Neufeld: Yours was based on liquid oxygen--
Konrad Dannenberg: Liquid oxygen and gasoline--
Michael Neufeld: And gasoline not alcohol--
Konrad Dannenberg: To my knowledge not alcohol; it was gasoline-- [[Crosstalk]]
00:29:40.000 --> 00:29:51.000
Michael Neufeld: So it was liquid oxygen and gasoline, of course that meant handling a cryogenic fuel in the Starthilfe--
Konrad Dannenberg: And that's of course pretty tough as you realize.
00:29:51.000 --> 00:30:09.000
Michael Neufeld: So it had its disadvantages, but, yeah as you say it may also have been army versus Luftwaffe, but, when you came that one tonne engine was still having problems.
00:30:09.000 --> 00:30:24.000
Konrad Dannenberg: Both of them had still major problems. One tonne for the Starthilfe and also the 1.4 tonne unit, and one of the major problems was really the efficiency, the combustion quality was just not there,
00:30:24.000 --> 00:30:48.000
and my main job was to find out how to improve the injection system. I don't know how well you know the design. There were fuel nozzles all around, I think, four rows of fuel nozzles. Some of them injected directly; some others atomized the fuel, and generated fuel mist, and we shuffled these around quite a bit.
00:30:48.000 --> 00:31:03.000
And we finally came to a design where lots of these holes could be just drilled into the wall; they were just straight holes, and we had only a few nozzles which atomized the fuel to improve or to quicken up the combustion,
00:31:03.000 --> 00:31:20.000
and that worked fairly, pretty, pretty well. And also when we finally put all these elements together, due to the additional mixing, apparently the combustion quality was pretty good when you used the whole, the larger system. There you have the picture.
00:31:20.000 --> 00:31:42.000
Michael Neufeld: Yeah, this is from Gerhard Reisig's article, series, and of course, you know he has a fairly detailed discussion of those propulsion issues on there, but you were, so there were still more refinements needed on that basic injector--had the Topf that went into the A-4-- [[Crosstalk]]
00:31:42.000 --> 00:31:51.000
Konrad Dannenberg: Right, also the LOX injection, you probably know the LOX nozzles in the center of the unit, and there is only one LOX unit to keep it simple, and that also, that had only straight holes in it.
00:31:51.000 --> 00:32:03.000
And the straight holes sprayed and they were supposed to spray over the entire unit so that you had LOX droplets right next to each and every fuel nozzle.
00:32:03.000 --> 00:32:19.000
Michael Neufeld: So I remember that from the pictures that there was like a little dome in the center, a dome was where the LOX came, was injected, and so that you just drilled straight holes there, you didn't try to drill special nozzle holes--
00:32:19.000 --> 00:32:33.000
Konrad Dannenberg: But the holes were under specific angles, therefore it's not straight spheres, spherical surface. It had some steps in it, ja. So that the holes could be easily drilled under a 90 degree angle.
00:32:33.000 --> 00:32:40.000
[[Crosstalk]] And that was one of my first tests to develop the LOX injection system and the fuel system.
00:32:40.000 --> 00:32:50.000
Michael Neufeld: How did you proceed in the test process, doing that? Did you just-- [[Crosstalk]]
Konrad Danneberg: Purely experimental-- [[Crosstalk]]
Michael Neufeld: Did you just try something different each time that you did it-- [[Crosstalk]]
00:32:50.000 --> 00:33:10.000
Konrad Dannenberg: Right, right, no, we worked with the University of Dresden, and they were specialists in fuel injection. And they consulted with us and they made recommendations for new designs and things like that, so it was not only my doing and my experimenting, but we had some scientific help, really-- [[Crosstalk]]
00:33:10.000 --> 00:33:17.000
Michael Neufeld: Uh huh. That was, was that the institute of Professor Wewerka, or was there somebody else--? [[Crosstalk]]
00:33:17.000 --> 00:33:27.000
Konrad Dannenberg: No, Wewerka was turbo pumps, and I don't right, offhand even recall who was the head there. I don't think it was Wewerka.
00:33:27.000 --> 00:33:39.000
Michael Neufeld: Yeah, I have some documents regarding Dresden, but I don't have them with me, so I don't remember who was who. I know that there was a whole group of people there, and they had there was one of your-- [[Crosstalk]]
00:33:39.000 --> 00:33:55.000
Konrad Dannenberg: We had Küttner there who was quite active and spent a lot of time in Peenemünde, but he was basically still stationed in Dresden. We had Lindenberg there. I saw Lindenberg's name. He was the very first one to die in this country in Fort Bliss still, and he was permanently stationed in Peenemünde.
00:33:55.000 --> 00:34:08.000
So he did practically all his work there, and again he helped in all these design activities.
Michael Neufeld: Officially, though, he remained at least for a while, an employee of the Technische Hochschule, Dresden, and not-- [[Crosstalk]]
Konrad Dannenberg: I think he did.
00:34:08.000 --> 00:34:19.000
I think he did, ja.
Michael Neufeld: Officially worked in the Institute at Dresden, if not he was there. The other guy was Küttner--
Konrad Dannenberg: Küttner, ja--
00:34:19.000 --> 00:34:27.000
Michael Neufeld: Were they involved from the beginning when you were there?
Konrad Dannenberg: Yeah, they certainly were relatively early, relatively soon involved.
00:34:27.000 --> 00:34:41.000
Now I don't know if they were there ahead of me. Again Thiel had all these contacts, ja, and he invited these people, he wrote the contract with these people, and it must have been around the time when I got there.
00:34:41.000 --> 00:34:59.000
Michael Neufeld: Yeah, cos I, I've seen the documents that indicate right in September 39 they brought Dresden in, and in fact in another folder, I don't think this one, I have the document that indicates the discussion at Kummersdorf between Thiel and a number of people from Dresden-- [[Crosstalk]]
00:34:59.000 --> 00:35:11.000
Konrad Dannenberg: Yeah, Thiel was really the one who had these connections, I'm sure he wrote the contract, though he provided the basic gist for the contract, and they probably had contracting people to actually write the contract.
00:35:11.000 --> 00:35:19.000
And you probably know we worked of course quite extensively with universities. Universities and also private industry.
00:35:19.000 --> 00:35:35.000
{SPEAKER name="Michael Neufeld} Yeah, I think the university angle: there needs to be a lot more done with that, and has been. I think that's a whole area of research that nobody has--everybody, every book states that well there was some university work, but that's one of the things that I want to cover, um--
00:35:35.000 --> 00:35:53.000
Konrad Dannenberg: And they wrote a lot of contracts. There may even have been some contracts in your stake, there, that were written by Dresden. Reports on injection, what kind of designs to use, what kind of designs were successful.
00:35:53.000 --> 00:36:08.000
- And I also started at that time, well, it was even while I was still in the university, I started to use a lot of N-A-C-A reports, you know before NASA we had an N-A-C-A, and I read quite a number of the reports written by a Mr.
00:36:12.000 --> 00:36:23.000
KONRAD DANNENBERG: -- something with Roth, Rothstein, Rothenberg, or something like that. And he did these reports for either Langley, or --
00:36:23.000 --> 00:36:27.000
MICHAEL NEUFELD: Ames?
KONRAD DANNENBERG: -- or Ames. No, I don't think it was Ames.
00:36:27.000 --> 00:36:34.000
MICHAEL NEUFELD: Louis?
KONRAD DANNENBERG: Lewis! Lewis -- I think it was working with or for Lewis.
00:36:34.000 --> 00:36:37.000
MICHAEL NEUFELD: This would have been on combustion and --
00:36:37.000 --> 00:36:42.000
KONRAD DANNENBERG: That was still jet engines, ja? Jet engine injection.
00:36:42.000 --> 00:36:46.000
And he studied also, what do you have to do in order to really have good, efficient combustion.
00:36:46.000 --> 00:36:50.000
MICHAEL NEUFELD: You sure it wasn't piston engine combustion?
00:36:50.000 --> 00:37:01.000
KONRAD DANNENBERG: Could have been piston engine combustion. He really did only injection studies, ja? And then he put a piece of paper under it and he measured where do you get most of your fuel?
00:37:01.000 --> 00:37:06.000
And then he tried to improve it to have an even distribution over the whole piece of paper.
00:37:06.000 --> 00:37:18.000
So he made some very basic studies. And I read quite a number of his reports and of course I drew my conclusions from these reports. And tried to implement some of his ideas.
00:37:18.000 --> 00:37:27.000
MICHAEL NEUFELD: So that there really was an influence from earlier - [[cross]] - aircraft engine injection?
KONRAD DANNENBERG: We had some pretty fair information.
00:37:27.000 --> 00:37:37.000
I think I mentioned I knew Goddard's book? I had that. And we apparently also, maybe again through universities, we also could get these reports.
00:37:37.000 --> 00:37:48.000
Well as I said, I was still in Hanover when I got a hold of these reports, and of course universities have normally pretty good libraries that contain all these reports.
00:37:48.000 --> 00:38:02.000
And I finally even met that guy in one of the earlier meetings here.
MICHAEL NEUFELD: Really?
KONRAD DANNENBERG: Ja, and he was also pleased, in a way, that his work was not only being used here, but even over there.
00:38:02.000 --> 00:38:07.000
MICHAEL NEUFELD: OK -- Thiel, I haven't asked you yet to describe him, or --
00:38:07.000 --> 00:38:15.000
What was he like as a person? - [[cross]] - What was his talent?
KONRAD DANNENBERG: He was also a very dynamic man, he was a little bit like von Braun.
00:38:15.000 --> 00:38:28.000
He was not quite as much interested in general publicity, he was more strictly engineering-oriented. And I think he was an excellent engineer - I think really most of the credit for the V-2 engine should go to him.
00:38:28.000 --> 00:38:38.000
And the engine was more or less in existence when I came up there - it didn't work, we had to make it to work - but the basic design was there. The combustion chamber was there.
00:38:38.000 --> 00:38:55.000
I think he was the one who came up with the idea of a turbo pump, and he worked with Wewerka and that was basically in the turbo pump area. He was the one who built the steam plant in order to drive the turbine.
00:38:55.000 --> 00:39:12.000
And we worked with Walter in that area; we got our hydrogen peroxide from Walter. And so Thiel should really get an awful lot of credit for that and of course since he died during the bomb raid on Peenemünde, he's normally not being mentioned too much.
00:39:12.000 --> 00:39:25.000
MICHAEL NEUFELD: This actually - I guess Reisig agrees with you because this article also emphasizes Thiel's role - maybe I should leave the diagram out --
KONRAD DANNENBERG: Yeah, and I think that was really the biggest loss for Peenemünde,
00:39:25.000 --> 00:39:37.000
when he died, when he was not there anymore. And he was working already on a Mischdüse, an improved version of the rocket chamber, which is pretty close to the Redstone engine.
00:39:37.000 --> 00:39:50.000
We were working already on these designs. And I think the Redstone engine was finally built this way by North American Rockwell, because Riedel again from the University of Berlin who worked with us in Peenemünde --
00:39:50.000 --> 00:39:58.000
-- he went finally, he was finally hired by North American Rockwell, and so he knew about all these ideas and he then implemented them.
00:39:58.000 --> 00:40:06.000
We tried to do it in Peenemünde, but we had considerable combustion instability problems,
00:40:06.000 --> 00:40:14.000
so the combustion you probably heard about, combustion instability.
MICHAEL NEUFELD: Right.
KONRAD DANNENBERG: And we never got over that so we finally decided to use this engine.
00:40:14.000 --> 00:40:27.000
If Thiel would have been there, I personally would guess that he might have succeeded in switching to the much simpler Mischdüse injection system.
00:40:27.000 --> 00:40:34.000
MICHAEL NEUFELD: Yeah, there are a lot of details that I want to get out of that, all of what you just said.
00:40:34.000 --> 00:40:52.000
So you came in and you worked on the Starthilfe motor and probably by 1941 sometime you had solved the problems with getting that to work without having burn-throughs, right? And combustion instabilities?
00:40:52.000 --> 00:41:02.000
And you were also at the beginning working on this 1.4 tonne thrust --
KONRAD DANNENBERG: Right. And actually these works went on parallel.
00:41:02.000 --> 00:41:12.000
We had two different test stands - the one-tonner was tested on one test stand, the 1.4 unit on another test stand, and so we could do the work parallel.
00:41:12.000 --> 00:41:18.000
MICHAEL NEUFELD: Was the 1.4 tonne the same motor that you used in A-3 and A-5 ?
00:41:18.000 --> 00:41:29.000
KONRAD DANNENBERG: It's actually this unit here, this head unit, and it was strictly a test motor, so it was only used for testing, it had no project application.
00:41:29.000 --> 00:41:40.000
MICHAEL NEUFELD: OK, so the A-5 motor was, was the something that stemmed from an earlier --
KONRAD DANNENBERG: That was an earlier design, ja.
MICHAEL NEUFELD: Right, that was, ok, that's right, that was this design --
00:41:40.000 --> 00:41:51.000
-- here - [[cross]] - it had a very long combustion chamber.
KONRAD DANNENBERG: Right, right, ja, and that was quite different, a very long combustion chamber, again probably people didn't atomize their propellants well enough,
00:41:51.000 --> 00:41:58.000
so you needed some time for them to react, ja? If you have a good reaction, you can do it with a very short chamber.
00:41:58.000 --> 00:42:11.000
MICHAEL NEUFELD: So, yeah, according to this description from Gerhard Reisig - in that motor you had the problem of - the very great length meant that you ended up getting combustion instability
00:42:11.000 --> 00:42:16.000
in there. You'd have good burning in one part, good mixing and burning in one part of the--
00:42:16.000 --> 00:42:28.000
and you'd get waves, standing waves set up, so that you'd have hot spots -- things like that.
KONRAD DANNENBERG: And I never had anything to do with that motor, that was the size I knew, designed and built already in Kummersdorf.
00:42:28.000 --> 00:42:42.200
It was tested finally in Peenemünde, in the A-5s of course, ja? So when I got into the act, we only worked on the A-4.
MICHAEL NEUFELD: So that the first thing that you saw was --
00:42:44.000 --> 00:42:46.000
MICHAEL NEUFELD: -- almost the end of the tape, but this side --
00:42:46.000 --> 00:42:50.000
MICHAEL NEUFELD: The first thing that you were working on when, was the 1.4
00:42:50.000 --> 00:43:03.000
I also know that they had, that you had experimented with a intermediate size, 4.2 - [[cross]] - which is 3 injectors--
KONRAD DANNENBERG: Right, 4.2, three systems in order to get some pre-mixing.
00:43:03.000 --> 00:43:08.000
And the 4.2-ton unit had therefore already a better exhaust velocity.
00:43:08.000 --> 00:43:17.000
We used exhaust velocity. In this country, use ISP, which is basically the same. A different dimension, but--
MICHAEL NEUFELD: Right.
00:43:17.000 --> 00:43:23.000
MICHAEL NEUFELD: When you came in - Do you remember whether, in the middle of '40, whether the -
00:43:23.000 --> 00:43:34.000
- there had already been work on the 4.2 - [[cross]] - ton motor, with three --?
KONRAD DANNENBERG: Ja, I worked on that also pretty soon after we had solved the problems on the 1.4 tonner -
00:43:34.000 --> 00:43:42.000
- whenever we had a good design, which we thought was a good design, then we introduced it automatically in the 4.2-ton unit.
00:43:42.000 --> 00:43:47.000
And again we had a separate test stand for that, so we could do all this work parallel.
00:43:47.000 --> 00:43:57.000
MICHAEL NEUFELD: As far as you remember, the 4.2 existed already? - [[cross]] - As a concept, or as an engine?
KONRAD DANNENBERG: I did not do the design of the chamber. Ja, so it must have existed.
00:43:57.000 --> 00:44:01.000
And even this chamber here existed already when I came to Peenemünde.
00:44:01.000 --> 00:44:11.000
MICHAEL NEUFELD: So you had already seen, it wasn't just a drawing board concept, the 18 - [[cross]] - injector--?
KONRAD DANNENBERG: It had been built already. It had been built.
00:44:11.000 --> 00:44:17.000
As I said earlier it didn't always work, ja? In fact in most of the cases it didn't work, it blew up.
00:44:17.000 --> 00:44:31.000
MICHAEL NEUFELD: Was it only- Do you know if it was only tested at Peenemünde or at Kummersdorf? - [[cross]] - The 25 ton?
KONRAD DANNENBERG: I don't think this was tested in Kummersdorf, it's a pretty large engine and you need a relatively big test stand for it.
00:44:31.000 --> 00:44:43.000
And we had these big test stands only in Peenemünde, that's why they went to Peenemünde to be able to build these big facilities and also to launch from there. So I don't think that was ever tested in Kummserdorf.
00:44:43.000 --> 00:44:56.000
MICHAEL NEUFELD: All right, I think you're right. 'Cause I don't think there was the, they didn't have the test stand of sufficient size to test the 25-ton motor. Umm, I'm just seeing if I have tape here--
00:44:56.000 --> 00:45:07.000
MICHAEL NEUFELD: So the, when you first worked with the 25-ton motor, when was that? Was that months after you got there, or --?
00:45:07.000 --> 00:45:20.000
KONRAD DANNENBERG: Well it was a little bit after I got there, I would say late '41, '42. It may have been a little earlier, let's say '41.
00:45:20.000 --> 00:45:28.000
MICHAEL NEUFELD: That's when the 25-ton motor was really put together and first actually tested.
00:45:28.000 --> 00:45:37.000
MICHAEL NEUFELD: As far as you know, the drawing board concept of putting 18 injectors together - [[cross]] - that had already been in existence?
KONRAD DANNENBERG: That was in existence, yeah, right.
00:45:37.000 --> 00:45:46.000
And there was nothing much I could do. I could only work on the details, on the injection detail, the mixing detail.
00:45:46.000 --> 00:45:55.000
And of course we still made a lot of changes. You may have seen also on the engine we have altered the rocket center, we had to introduce a lot of additional cooling.
00:45:55.000 --> 00:46:08.000
FM cooling we called it, because basically it was done for the throat area, we called the throat area FM. F for Fläche, Minimum.
00:46:08.000 --> 00:46:16.000
And in order to prevent burn-throughs here we injected extra fuel, just on top, err over, uh, the FM area.
00:46:16.000 --> 00:46:31.580
And later on we found out we also have to introduce additional fuel and all these other things. So that detail of the design was not there, that's what I had to develop in order to make it work. But the basic principle was in existence.
00:46:35.352
