"Paul Suhler Part 1" Avstry #7a
We learn about the early days of the Archangel Project as well as the SR-71 Blackbird. And how these aircraft were designed and build to penetrate deep into foreign territory and return with vital intelligence.
Published Date: Sun, 02 Sep 2012
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J.R. Warmkessel: Welcome, Paul. Thank you so much for joining us today.
Paul Suhler: Well, thanks very much, J.R.
J.R. Warmkessel: I always like to start these podcasts by asking our guest what aviation credentials or licenses or whatnot, that they hold. So if you could tell us maybe a little bit about that before we get into the main topic.
Paul Suhler: Okay. My aviation credentials have nothing to do with what I'll mainly be talking about tonight, but as background, well, I was in the Army at Fort Ord up in Monterey, California about 30 years ago. I got a private pilot's license as a member of, of all things, the Navy Flying Club, which is associated with the Naval postgraduate school. I went on through a commercial license and got instrument to multi engine ratings, and I kept that up pretty heavily for about three years then dropped it while I travelled around the world and resumed flying a little bit while I was at graduate school at University of Texas at Austin, but then I had to give that up because I took up skydiving and I didn't have money or time for both. So eventually I worked by way up to, I believe it was a C license from the U.S. Parachute Association, and I guess I have a total of about 530 jumps, but at this time I haven't jumped in about 18 years. So I'm really not active in any aviation at this time.
J.R. Warmkessel: Now, the important question is, have you skydived from the outfit down at Fort Ord?
Paul Suhler: No, there was...we didn't do that at all at the time I was there. I was skydiving originally out of Skydive San Marcus in Texas and then later up in New York while I was working at IBM at the ranch, the blue-sky parachute ranch, and then when I moved out here to California 20 years ago I went to Lake Elsinore and to Perris Valley skydiving.
J.R. Warmkessel: Maybe if you decide you're going to take it up again you can give them a try.
Paul Suhler: Yes, if I do.
J.R. Warmkessel: So you have an interesting book, I understand. Maybe you can tell us a little bit about it.
Paul Suhler: Well, the whole thing actually started as a hobby, and, I guess to go back, my association with the Blackbird, I guess, was really none. I first heard of it when I was 10 years old in 1964 when LBJ announced what, at the time, they called the A-11 and then some months later announced the SR-71 reconnoissance aircraft, and I never really knew much about it at the time. And then in the '90s, and I still don't know why, I got an interest in maybe wanting to understand why the CIA had Lockheed go through a dozen different designs before they were finally happy with it. You may know that in 1993 Jay Miller produced a book called, it was the official history of the Lockheed Skunk Works. It was on the 50th anniversary of their founding, which was a kind of informal affair, but that happened back during World War II. Sometime in the mid-90s I read that book and one of the most interesting chapters was about the A-12, the first of the Blackbirds, the one that was done for the CIA. And it was called the A-12 because it began with a design called Arc Angel One and worked it's way through design number 12 before everyone was happy with it, and somewhere that caught my interest as an engineer. I'm a computer engineer and I've seen lots of cases where projects get dragged on, and on, and on through many levels of design because the customer keeps changing the requirements. So I wondered if that was the same sort of thing that had happened to Lockheed, and I never really did anything with that interest for awhile, but eventually I decided I really should try to write a book, and so I just started writing letters to people and getting names and eventually interviewing and then getting more documents out of the CIA, and in the end I published through the American Institute of Aeronautics and Astronautics, a book called From Rainbow to Gusto: Stealth and the Design of the Lockheed Blackbird, and what it really does is trace the reasons that the Lockheed Blackbird ended up looking and flying the way that it did in terms of the original requirements. So to onto that and understand where all that came from, you have to go back to the mid-1950s. All of the national leaders, especially Eisenhower, who had been supreme commander in Europe, had, you know, been through the big shock of Pearl Harbor where the United States was without, you know, to most of these people it was a tremendous shock when that happened. They didn't ever want that to happen again. Then in 1949 the Soviets exploded their first atomic bomb, which was a surprise in itself but suddenly everyone realized that there could be another Pearl Harbor and this time there could be tens of millions of Americans dead, and that was the foundation, the main reason, that people needed intelligence about the Soviet Union. Being a closed society, it was very hard to figure out what their capabilities were for attacking the U.S., much less what their intentions were. Part of this goes back to a gentleman named Richard Leghorn, who flew reconnoissance missions in the Army Air Corps during World War II. After the war, he began putting together sort of a theory of national reconnoissance, and he began giving talks about this and explained the need for strategic reconnoissance in that the next war might start so suddenly you didn't have time to gather information later. You had to have it right before hostilities began, and that was sort of the beginning of the Overflight Program over the Soviet Union. Now, a better starting point though is with a group led by Edwin Land. There were a number technological capability panels, TCPs as they were called, and Land ran on in the 1950s that looked at technical means of gathering national intelligence, and they had called to their attention this design that Lockheed had come up with called the CL-282. It was basically a high-altitude glider. It looked like an F-104 with stretched out wings, and it would be a subsonic aircraft but it could fly extremely. It would carry only a single engine, and could fly over the Soviet Union. Land's group got wind of this and started pushing the idea into government circles, trying to get interest in this, and what eventually happened is that the CIA was tasked by Eisenhower with implementing this airplane, getting it built through Lockheed, and operating it on flights over the Soviet Union. That was really the beginning of the Blackbird because what happened as soon as the first overflights happened over the Soviet Union, which began on July 4 of 1956, immediately the Soviets were tracking all of these flights. It had always been their hope that the aircraft would never even be noticed on radar, and if if was noticed, well, hopefully they wouldn't be able to track it and see where it's going, and then, well, if it were being tracked then hopefully they couldn't shoot it down. Well, they sort of got stuck for about four years between those last two steps, but of course eventually in 1960 the U-2 was eventually shot down, but by then the CIA had something else in the works. So once it was recognized that there was this huge danger to the United States, one of the top priorities for American intelligence was to find out the number of Soviet bombers. That was assigned to the CIA as their highest priority. Now, what the military services were saying, especially the Air Force, is that there were lots and lots of Soviet Bombers and we need to be able to defend against them, and the defense contractors were saying, "You need to buy lots and lots of our bombers to defend against all of those Soviet bombers that are out there." Well, Eisenhower was a little skeptical of that. You know, granted, they may have been not as cynical as that sounds because certainly the Air Force, had there been a successful attack, they would have been the main ones blamed for the success of the Soviet attack on the U.S., but, nevertheless, there were a lot of interests for spending a lot of money, but Eisenhower had this equation in which the money we spend on one bomber means that there are 20 schools that we cannot build. So he was very hesitant to just start spending enormous amount of money on national defense unless there was solid evidence. So, where did the evidence come from? Initially, there really wasn't any. The U-2 program, as it go started, Project Aquatone, as the CIA originally called it, was really the first solid technical intelligence that we had about the Soviet Union. Like I said, on July 4, 1956, the first U-2 flights began over the Soviet Union. Six days later, there was a protest note from the Soviet Union saying, "You've been flying a twin engine bomber over our territory and it will stop now." Well, Eisenhower told the CIA to terminate the flights immediately, and the CIA, by that time, had made eight or ten flights and as they got the film back from the remote locations, they began to see just how valuable this was, so they didn't want it to stop at all, and certainly Eisenhower was torn both way. He knew that technically a flight over the Soviet Union was an act of war. One reason he went to the CIA is that they had nominally civilian pilots so at least it wasn't a military aircraft, so technically it wasn't an act of war, but, nevertheless, it was a big provocation, but, on the other hand, he saw how valuable the information was. So, how to continue this? Well, the first hope was that they could find a way to make the U-2 either invisible to radar or more difficult to notice. About six or seven weeks after the termination of flights, on the 16th or 17th of August of 1956, Richard Bissell, the director of the CIA who had been running the U-2 program, convened a meeting with some technical experts. It included Kelly Johnson, the head of the Lockheed Skunk Works who was responsible for the U-2, Edwin Land, who as I mentioned before was not just the President of Polaroid but an advisor on various defense councils. They also had Edward Purcell, a nobel laureate in physics from Harvard, Stewart Miller, a physicist from Bell Labs, and Herbert Miller, a physicist who worked for Bissell at the CIA. They worked late into the night, past midnight. They went through, according to Kelly Johnson's notes, two bottles of White Horse Scotch, and then they resumed early the next morning, everyone including Bissell, and they decided that they probably could come up with some ways to at least reduce the radar backscatter or the radar cross-section of the U-2, and that became Kelly Johnson's top priority and Edwin Land's as well. So what happened next is that Land went to MIT Lincoln Labs in Massachusetts. This was a government lab carrying on secret work to develop radar and defenses against radar and general air defense for the continental United States. They had, as I said, a great deal of expertise in radar, so Land went to the director, who pulled in three people. They were Frank Rogers, PhD, who was assistant head of the radar division, and then two group leaders who worked within the radar division, Bob Knacka and Tom Bazemore, and he took them away offsite. They drove into parking lot of an Air Force facility that was still under construction so there was nobody around, and in the middle of August they rolled up the top on this convertible, rolled up all the windows in the morning heat so that nobody could hear them, and Land began to explain that we were flying an aircraft over the Soviet Union, which of course they had no idea about, and that we had to find a way to make it invisible to radar. So these people went back to Lincoln Labs. Rogers began recruiting people. They found a little private place to work. At that time Lincoln Labs was composed of three or four story buildings laid out on a sort of herringbone patter, and on the roof of one, the B building, there was a little, what he called a shack. He said it looked like it hadn't been occupied since the building was originally built. Well they started stealing equipment from other projects and hauling it up to the roof and putting it in this little shack, and that's where they began doing their work. Eventually they built small scale models and measured them up there and worked out various pieces of equipment, but that was carried out over a longer period of time. So this was the beginning of what the CIA called Project Rainbow. Why rainbow? I don't know why they chose that name. R, for radar perhaps, but it turned into a great deal of research. The ended up measuring the radar cross sections of U-2s in flight. They measured models, like I said, and U-2s on the ground, and they experimented with a lot of different materials and shapes to see what they could do to reduce the radar backscatter. There were contracts let to Westinghouse and to EG&G because there was so much work that the people at Lincoln Labs couldn't handle it. At Lockheed they began developing their own internal skills. Kelly Johnson brought in people from other parts of Lockheed, including Ed Lovick, a physicist, and those people went to work under L.D. MacDonald. Throughout the work they come up with, the Lincoln Labs people initially and then they were helped by the Lockheed people, they came up with three basic treatments. Now, the first of this was a skin treatment based on an idea by Ed Purcell, and this is worth a story in itself because this was very, very early in the work. He came up with an idea. Rogers's people came up with this material, and they applied it to a flat plate of aluminum, and they took a radar horn, you know, a very small radar transmitter, receiver, and they put the horn antenna right down on a plain, untreated aluminum plate and they measured the amount of energy that was reflected. Then they moved the horn over to this treated plate that used Purcell's idea, and they got a much lower return, and this sounded great. So Bissell had Frank Rogers go out to brief Kelly Johnson. He took the equipment along out to Burbank with him, and they demonstrated this, and Kelly was suitably impressed and they decided that, you know, yes, this project really did have some possibilities. Rogers went back to Lincoln Labs and, I believe it was Bob Knacka who's doing some further measurements, he tried doing the same test but at different frequencies, and suddenly, when the treated plate was giving a bigger response than the plain aluminum and it took a while to figure out what was going on, but because he had taken this radar horn and put it right down on top of the plates, they were really just creating a chamber with all sorts of reflections inside and the amount of energy didn't have so much do with the the treatment on the plate as to the frequency and where the echoes were going inside this radar horn. So they went back and talked with Purcell about this and they realized that what they really had to do was put the target they were going to measure a long way out from the radar, which is much more like what you would be doing in real life with a radar dish trying to track a flying aircraft hundreds of miles away, and once they did that, they did actually find that there really was a reduction in the return using that technique. But if they had done the experiment a little bit differently in the beginning, it would have looked like a failure, and that might've killed the whole project right at that time. At any rate, this continued and this became the first of the three concepts of what they tried to do to the U-2 to reduce its radar cross section. The material they finally produced was called wallpaper. Again, this was based on Purcell's original concept, but what they were trying to do is reduce reflections from a radar that had a wavelength of about 16 inches. That was the typical search radar as used by the Soviets. Now, there was a problem though. What you want to do when you use a material like this is set up interfering reflections, and to do that the material need to be about a quarter wavelength in thickness. In this case it would've had to have been about four inches thick. Well, that would've added a total of eight inches to the diameter of the U-2, which would increase what aerodynamicists call the wetted area and greatly increase the drag. Kelly Johnson, on the other hand, had given them a maximum thickness of one quarter inch. Well through some very clever electrical engineering, they were able to come up with the material that acted as though it were four inches thick when it was only a quarter inch. It gained a sort of effectiveness factor of 16, and that did reduce the reflections of the fuselage, which is where they mainly applied this, but there was a problem because this stuff also was a thermal insulator. In fact, they started it calling it thermos and it would trap heat, and it turned out they finally realized how bad an idea this was when a lucky test pilot named Bob Seeker was flying the original prototype U-2 with this treatment applied. He was at altitude probably around 70,000 feet when the build up of heat caused the engine to stop. That stopped pressurization in the cockpit and he was wearing an early-generation pressure suit which had a hinged faceplate, and as the pressure in the cockpit dropped the pressure inside soon popped open the faceplate and within a matter of seconds he lost consciousness. The U-2 went into a flat spin. Seeker woke up shortly before he crashed. He was able to bail out but he didn't have time for his parachute to open. So they lost the airplane and they lost the test pilot, and that was kind of the end of the idea of using this treatment they called wallpaper. Now, the next one was called trapeze because it looked like some rig with a lot of cables. They ran a line 40 inches in front of and parallel to leading edge of the wing and 40 inches behind the trailing edge of the wing and similarly on the horizontal stabilizer. There were also, cord wise, were front-to-back stabilizers that helped hold this in place. Now this is the invention of an antenna theorist at Lincoln Labs, and he's kind of an enigma because he came up with this really brilliant idea but he will not let anybody identify him to outsiders like me. So I don't know the guy's name and he's never seen a copy of the book that I wrote and just doesn't want to be...just doesn't want to talk about this. It was secret all those years and he'll leave it secret. He seems happy with that. But what they had observed is reflections off the wings, and when they started looking at simple shapes they just took a long bar of metal and got similar reflections, and what happens is that when the radar energy comes in at an angle to the leading edge it tries to set up, it tries to induce electrical currents in the skin of the wing that would go faster than the speed of light. Well that's impossible for any, you know for an electrical current to flow faster than the speed of light in metal and it results in energy being reradiated in different directions. They call them rhombic lobes because they look like the lobes describing how radar, radio energy is broadcast from a so called rhombic antennae. Anyway the idea of this antennae theorists was to put these leading and trailing wires then with wires that ran back to the surface of the wing, the leading and trailing edge of the wing, to form basically little squares. And that had a way of shorting out the, these currents that were trying that the radar beam would induce in the wing. And it greatly reduced the reflections. So that seemed like a fairly useful idea. So that was the second idea, trapeze. Now the third one was to run wires parallel to the fuselage so there were probably a set of eight or ten wires that began at the nose and ran along the sides, and one even ran over the top of the canopy after the pilot was inside and they could string that across. And there were also wires that run from front to rear on the vertical stabilizer. And these were set, expected a quarter of the wavelength they expected for the radars. They were set that distance out, so they would create a reflection that would interfere with the reflection off the main fuselage. Kelly Johnson didn't like this. He said he didn't know what the Reynolds's number was of the wires so he couldn't really use it to get an estimate an accurate drag. But one of the pilots claimed, and they never told Kelly this, that it actually improved the handling of the airplane. Well the problem of course was this added weight just like the trapeze wires and it reduced the altitude of the airplane. And altitude was one of the things they had going for them to keep them from being shot down. They did try flights with this over the Soviet Union. In one declassified CIA document it talks about how American satellites tracked the aircraft flying out after it had been to the skunk works to be refitted. And those tests ran from the fall of 1957 into the spring of 1958. But by late 1957 they realized that things weren't working. Frank Rogers explained the situation to Bissil that yes we reduced the radar cross section somewhat but we've just about hit the limit. And Bissil said so you're telling me the ship is still sinking, but maybe more slowly. And Rogers laughed, but it was, it was a pretty good summary of where they were. Eisenhower of course was not satisfied. He wanted zero chance the Soviets were going to see this thing so he you know continued for the next few years to allow flights of the U2 when they had very very high priority targets. But he was never happy with that. So by 1957 December they were looking ahead to what they called Rainbow phase 2. Bissil wrote up a memo describing the basic techniques and there were four. These techniques would be things they would apply to a new airplane. Number one was to shape the aircraft to reflect energy away from the radar unit. Now that had a big advantage because in principle that could work at all frequencies. Now like I mentioned these wires their spacing from the airplane was only valid for a particular frequency. Or would only work best at a particular frequency. But if you could get it shaped right that would work at all frequencies, a sort of broad band solution. Number two was to build this new airplane with materials that would absorb radar energy. Simply turn it into miniscule amounts of heat and not reflect it back. Number three since they had observed that the wing edges gave big reflections was to find a way to so called soften these electrically to reduce reflections. If anyone has ever taken an electrical engineering class and played with a transmission line you'll see that when you send a signal down this transmission line and it's open at the end you get a big reflection. But if you put a resistive so called termination on that then the energy is basically turned into heat and you don't have a big reflection coming back up the line. Same thing works with a radar beam moving through free space. If you just have unprotected metal it will reflect. If you can have a slow transition from the impedance of free space to the impedance of the metal which is very low that gradual change will prevent reflection. So that softening was the third technique. And the fourth technique was using transparent structures, where they could they would simply let the energy go through without reflecting. So those were the ideas that they had in about December of 1957. Now one of the first big discoveries as far as shapes was thought up by Frank Rogers. Apparently he would go away for days at a time thinking about things and then come back to Lincoln Labs. And one day he came in and picked up a saucer in the cafeteria, found one of the engineers and told him to go find some aluminum foil, measure the reflection of the saucer from below then put on the aluminum foil and measure it again. And the guy did this, and he found that when the saucer shape was covered with the aluminum foil it gave almost an immeasurable reflection. This seemed like a great idea. He asked Rogers why and Rogers said well when you see it from below all the reflections are going away from the radar unit. And if you, you know, were to sit down and draw a picture you can see that yes all the reflected radar energy should go in a different direction. So again this sounded like a great idea and Bissil sent Rogers and this time a computer engineer who joined the group named Norm Taylor, sent them off to Burbank to tell Kelly about this. And they pitched it wrong. Rogers said you've got to make the next airplane shaped like a flying saucer. And Kelly said, according to Norm Taylor, Kelly said something to the effect of well for Christ sakes I can't make anything like that fly stable. You don't know anything about aerodynamics. And Rogers could be as pig headed as Kelly and he wasn't intimidated so he said well you don't know a damn thing about radar. And that was the end of the meeting. They headed back to Boston. They sat down with Bissil and explained how everything had blown up and he said well you're going to have to educate Kelly about this. And so what the Lincoln Labs folks finally decided was they couldn't tell Kelly what the airplane had to look like but at least they could give him some basic principles. So they tried to figure out what those were and they came up with three. The first thing was don't have any straight lines on the airplane, particularly like the straight leading edge or a straight flat side on the airplane. Second was to have no concave surfaces you know something like looking into a radar dish would be concave, that would give you a great reflection. And don't even have any flat surfaces if they're going to be aimed right back at the radar unit. You can have them but they have to be reflecting into a different direction. So with those three principles they fed into the skunk works and Kelly tried to make some use of that. Now to give him credit he actually did try to make a saucer shape fly in a stable manner, but they couldn't do it. Now these days they could probably get a lot closer to it with active controls like you see on things like the F 117 and other stealth fighters that are not statically stable. But back in the 1950s they simply couldn't do that. So the saucer was out at that time. At this point the CIA did something that they would do periodically, which is change the name of a program. So where they had Rainbow, the attempt to make the U2 invisible to radar, they had some number of people that didn't need to know they were going to try to build a different airplane. So they did all the work toward a new airplane under what came to be called project Gusto. And people who knew about Rainbow but didn't know, need to know about Gusto, were never briefed into the new project. They were told well we tried to look at this, it didn't go anywhere, that's the end of it thank you. But of course all the principles did keep working on what was called project Gusto. So Lockheed started work on subsonic designs as the U2 has been. They had four basic designs they came up with over a course of a few months. Two were fairly conventional looking but they had some concessions to radar cross section and they promised pretty good performance. The others were more radical looking and would be stealthier although people didn't use the word stealth in those days. But it would probably cost them in performance. So the very first one looked kind of like a U2 that it had the sides flattened and the wings blended into the bottom of the fuselage. This they called the B2 of all things. Probably just a play on U2. It you know anticipates the northern B2 spirit stealth bomber by twenty-five years or more. And it's just a coincidence. But they originally worked with some transparent materials on the fuselage of this airplane. That in itself turned out to be not a really hot idea. Ed Lubbock told me that he knew from the beginning that, that wasn't going to work and one, one good example is what happens with the engine. Because if the engine is exposed through say a fiber glass skin, you're going to get all sorts of reflections off the engine. Similarly for the fuel tank as part of their modeling you know they would do radar models of all of these things. They had a scale model that included a fuel tank. In the fuel tank they put in kerosene which is pretty much what jet fuel is. And they could get reflections off that. Moreover when they vibrated the model a little bit they set up standing waves, ripples inside the fuel tank and they got even better reflections off of that. So it turns out that trying to have a transparent structure wasn't all that useful. And besides fiberglass does reflect at certain frequencies and the ones where it's transparent it's not really such a hot idea. So that was so much for the B2. Now the next one, again the more conventional design they simply called general arrangement number two. If you know what the I guess OV 10 Mohawk looks like. A straight winged airplane, twin booms that go back, tails that go up and then kind of a high tail connecting the vertical stabilizers that are coming off those booms. That's what this airplane looked like. Now they did some interesting things. They had a single jet engine and they put that kind of on top of the wing. The actual inlet was behind the pilot's canopy so the canopy would prevent radar energy from getting into the inlet. Because again by then they had found out that the compressor on the face of the turban looked gave really really good radar reflections. Similarly they could get reflections from the rear of a jet engine, so in this case they had the wing extend back a bit so that the ejector of the engine was not hanging directly out in space as it is with say the U2. There was a certain amount of material underneath that horizontally that would protect that as well. The booms that went back from the wings to the vertical stabilizers were an inch and a half thick fiberglass honeycomb with oh six or seven different layers. And they found this was fairly good but you know again there were problems with some of the fiberglass materials allowing metal inside to generate reflections. One other thing that they did on that, the vertical stabilizers they sort of tilted inward about fifteen degrees. That meant that the airplane could bank up to about fifteen degrees before it would be reflecting radar straight back out horizontally. Now after that they began looking at the more radical designs. One was done by a guy named Ray Kirkam and they called it the bat plane. I never found any proper drawings for this, there's just a single sketch. And it has kind of an oval wings stretched out very much from side to side then a long narrow waist and then a horizontal stabilizer that is almost circular when you look at it from the top. There were a pair of jet engines on either side of the cockpit. They were sort of buried in the wing. So they sort of blended the engine itself and the little fuselage with the pilot in it into the wings. It was in some sense a kind of approximation of the flying saucer shape that Frank Rodgers had come up with. So that was the bat plane. And the final one was known as Gusto Model 2. This was, you know it sort of began with the flying saucer so if you could just imagine the disk that has a compartment for the pilot in the center, two engines on either side of that. They tried measuring that with radar absorbing material around the edge. Now that wasn't going to fly so they tried sticking on sticking on transparent, or radar transparent wings, plastic wings that went out. They were swept back slightly and had vertical stabilizers on the tip of each wing. So that was modeled in a couple different ways. One was a pure metal skin. And then they tried putting radar absorbent wedges around that. Now if you've ever seen the inside of a radar anacord chamber they have all of these cones of radar absorbing materials. Well Ed Lubbock had this idea that you could simply take that slice it to fit into the leading edge of the wing and you'd end up with a bunch of sort of triangular wedges inside the surface of the wing that would dissipate the radar energy. And when they applied that treatment inside this, the Gusto Model 2, they found that that gave the least radar return. It was significantly less even in the exact same shape but done in all metal. Problem was with flying wings they're not nearly as efficient as a regular airplane that has a horizontal tail that is a good distance behind the center of gravity. They have to use what's called a reverse camber wing in order to get some a little bit of force down on the wing in order to lift the nose of the airplane and keep it balanced. And this costs you in range. So that was the problem basically with the Gusto Model 2 was great, pretty good for radar but it simply didn't have the range. By then the CIA came up with the requirement that you needed 2,000 mile nautical mile radius. You had to be able to fly in over denied airspace, 2000 miles turn around and come back, or if necessary keep going another 2,000 miles to exit the denied air space. And this airplane simply couldn't do it. Now at that point they were beginning to do a number of studies of how to beat radar, and one was called the blip scan study. Back in the 1950's they didn't have computer enhanced radars like you would see today. You had a human observer sitting at a big round scope called a PPI, a plan and position indicator. At the center of the circle was a point representing where the radar actually was on the ground and as the radar rotated you would get echoes back at times and theses would be turned into blips on whichever heading the radar happened to be when it encountered the target. So you get these little fuzzy blips and as an airplane flew through the space it was scanned by this radar you would see a series of blips flying, you know moving along. Well what they thought and they did a lot of number crunching on this was that if you could make those blips fewer and fainter then the operator might not see it. One guy put it in sort of molecular engineering terms and said an operator is staring hour after hour at a plan position indicator was not an operable detector by at least several decibels. And yeah, certainly a guy sitting at a scope is going to get tired after a while. He's not going to notice, he's going to look away and hopefully if there's fewer blips for him to notice then he might let the airplane get by. They came up with three objectives. They decided if the airplane could fly at ninety thousand feet at a speed of Mach 3 and you could reduce the radar crawl section to less than ten square meters and preferably down to five square meters it would have a very low probability of being detected. Having a speed of Mach 3 makes it about four times as fast at the U2 was. Which means as it goes through the area scanned by the radar you're only going to be about a quarter as many blips. If you're higher the energy coming back is going to be less and the blips will be smaller, and if you reduce the radar cross section the blips will be smaller still. So that was the theoretical basis for doing a high speed stealthy design. Now at this point the story has to take a little bit of a detour because Lockheed began doing the really serious high speed work on a completely different project. In the 1950s the Air force and other people were interested in liquid hydrogen as a propulsion fuel for aircrafts. One of the first proposals handed to the Air force was from Randal Ray a British engineer who had come to the United States and was working with Garrett Corporation. They wanted to build a reconnaissance airplane powered by liquid hydrogen. And their first proposal to the Air force was a propeller driven sail plane that could fly at extremely high altitudes approaching 100,000 feet if I can remember correctly with a simple motor inside that would burn liquid hydrogen and through a belt drive system turn this propeller that was up through the fuselage. Well the Air force said okay there might be something to this and they sent them to go to work. Well they got over ambitious. They came up with a large turbo jet called the Rex 3 that will burn liquid hydrogen. And they decided they would end with an airplane going Mach 2.25. Now, they didn't have any airframe expertise so they contacted Kelly Johnson. And Kelly Johnson's group designed what they called the CL 325 which was a long thin fuselage, well actually it looks a lot like and F-104, long fuselage, sort of straight trapezoidal shaped wings and a high T tail. And this was about a 3 mil contract on Lockheed's part. They gave the drawings back to Garrett and to Randolph Rae and they presented it to the Air Force. And apparently when they made the presentation, there was just dead silence in the room, because the last thing the Air Force has seen was a little bitty propeller-driven, something not much more than a motor glider. Instead what they got was a 160-foot long Mach 2.25 aircraft driven with these, sort of, turbojets powered by liquid hydrogen. And they realized that Garrett, who had never built a turbine bigger than about eight inches in diameter, was in way over their heads. So, that was pretty much the end of the CL-325.
However, Kelly Johnson realized what the problems were with that, and he decided that he would just sort of try a new proposal. And this became the CL-400. He went to someone who had a lot of experience building high-speed engines, Pratt & Whitney, who developed what they eventually called the Model 304-2 liquid hydrogen turbojet. It became known as the Swamp Monster because by the time they had it running at their Florida Research and Development Center down in the Everglades, it made these horrendous amounts of noise. They also built some large plants to produce liquid hydrogen and thought they might be able to get up to about Mach 2.5.
The initial design of the CL400-10 looked a lot like the CL-325 that Kelly had designed for Garrett and Randolph Rae. There were a few differences, but it was really just a single-seat aircraft 160 feet long. The fuselage was almost completely a dewar which is an insulated cryogenic storage tank. If you're trying to avoid having a lot of heat loss, or rather heat gain into your liquid hydrogen, the ideal shape would be a sphere, it has a minimum surface area for a given volume of fuel. Well, you need more than that, so a good approximation is kind of a long cylinder with hemispherical ends. And that fits really well inside a long aircraft fuselage. So the CL-400-10 and all the other CL-400 designs that were to follow, had this enormous dewar inside the fuselage.
Now for whatever reasons they chose to put the Model 304 engines all the way out on the wingtips, I've never really had a good explanation from any of the few Lockheed people I've interviewed. It was a multi-engine pilot that thought of having turbine engines, say, 40 feet out from the centerline and then losing one sounds like a prescription for being powered into a flat spin really fast. But they were hoping that these things would have sufficient reliability, I guess, that that wasn't a problem. So, that was the first design, the 400-10. The problem was the range was still too short.
Now, if you were building an airplane with a conventional hydrocarbon fuel, you would just put fuel tanks into the, into the wings. But they couldn't really do that because these had to be insulated and that adds a lot of weight for the volume of hydrogen you're gonna add. So, if you're gonna try to add a bunch of dewar inside the spaces of the wing, you really end up adding a lot more weight than you make up for in added fuel to burn. So, they tried making these airplanes bigger and bigger. They eventually got up to a giant called the CL-400-13 that was 300-feet long and carried two crew members and a few hundred pounds of cameras. And it was, the range was still too short because they couldn't put fuel in the wings, they were never really able to get enough range out of any of the designs.
Eventually, Kelly Johnson terminated the work. The Air Force was still kind of enthusiastic about that, so they kept funding Pratt & Whitney who did a lot of work on the Model 304, but eventually even that ran down. But there was one really good thing that came out of this, which was Pratt & Whitney's knowledge about how to build engines that burned liquid hydrogen. And the main result was the RL-10 rocket engine which has launched well over a hundred spacecraft and is still in use in later variance today, more than 50 years later.
That project was called Suntan. And that was Lockheed first dipping their toes into a high-speed flight beyond Mach 2 which is what they had experience with in the F-104. Now at this point Kelly Johnson was taking his designs back to the Advisory Panel headed by Edwin Land who was telling Dick Bissell and the other folks at the CIA what they thought of these designs.
There were some Navy people on the Panel and they had gotten in bed with Goodyear on a project that apparently was called Champion. They wanted to get into the strategic reconnaissance business too, the way the CIA had and that the Air Force was trying to get back in. Well, what does the Navy have to offer? Aircraft carriers. Their idea was if they could have a high speed aircraft, they could put it on their carrier go steaming up to, fairly close to the Soviet Union, launch the thing and then recover back to the carrier. The problem was that you're talking about a really big airplane and it wasn't gonna fit very well inside a carrier.
So they decided, working with Goodyear, that they wanted an inflatable airplane. They want wings that could be rolled up and then rolled out when the airplane was on deck, pressurized and off the thing would go. Now Goodyear had made this work with a little thing called the Inflatoplane back in the '40's. It was a one or two-seat airplane that went about 80 or 90 miles an hour. They were talking about doing something a lot bigger.
One of the ideas for launching this thing that they presented to Kelly Johnson while he was visiting the Land Panel was to launch, carry the thing up to altitude with a balloon, light off its ram jets and then drop it from the balloon and off it would go into the Soviet Union. Kelly did some quick computations of what it weigh and what it would take for a balloon and he figured it would be about one mile in diameter, the balloon to lift this thing. And he famously remarked, 'Gentlemen, that's a lot of hot air.'
But nevertheless, the Land Panel asked him to go back and do an evaluation of this, you know, do some serious design and see if there is really any, any technical merit in this inflatable airplane idea. So, he did. And it turned out that, in fact, it was not a very good idea. The inflatable airplane would be about 15% heavier than an equivalent one made of metal. And it was much heavier than it had to be to do the mission and all in all it was a bad idea. They looked at several ideas of towing it to altitude, launching it with a rocket and various things, and none of them ever really made much sense. And he eventually brought the bad news back to the Land Panel.
But in the meantime, and we're now talking about April of 1958, while his team was wrapping up the CL-400 hydrogen designs for the Air Force, Kelly started making notes in his notebook about his own Mach 3 design, a new airplane that would not burn liquid hydrogen, but it would burn the hydrocarbon fuel. He set the basic requirements as we had already talked about, 90,000 feet, Mach 2, he looked at using the J-58 engine which was, at that point, being designed by Pratt & Whitney for a Navy contract. One crew member, maybe two in the future, have a range of 2,000 nautical miles or radius, payload 500 pounds of cameras. He estimated he'd get a lift over drag of wing at that speed of about seven or eight. He worked through various rough estimates and came up with numbers that made him think that he could actually make this thing work. So, he made a sketch of what the airplane would look like, which was kind of a conventional thing. I guess it looks more than anything else like the Vigilante, the Navy Mach 2 reconnaissance aircraft. It had the J-58 engines podded right next to the fuselage under a sort of trapezoidal shaped wing and then some triangular horizontal stabilizers that might be able, depending on the design, they might fold down at some point during flight. And then he put this away while his team finished the work on Suntan.
Then in June of 1958, one week after they gave their final reports to the Air Force on Suntan, he called in Dick Baney, who was the deputy head of the Skunk Works and who is really one of the unsung heroes of the Skunk Works, Ed Baldwin, one of his principal designers and a couple of other engineers. He had sat down, Kelly had sat down at his drafting board and drawn up a nice design for this airplane and he handed it to them and said, "see what you can do with this." And that was the beginning of Archangel 1, the very first mock 3 design to come out of the skunk works. The goal was to have the desired performance 90,000 feet at mock 3 with the least development risk. Hopefully, they can develop the thing within 18 to 24 months from go ahead to first flight. They decided they'd stick with the fairly conventional airframe configuration, no unflightable wings, no transparent structures, anything like that. They use a version of titanium called B120VCA. That would be the primary structural material. And the advantage there is they could use that to, or they felt at that time they could use that to build a standard design with rings going around the- around transverse to the length of the airplane. And the longeron, the structural members that run from front to rear, and they would connect the rings, and then they would put the skin on this. Well, using titanium, they could get the same strength with much less weight than they could with steel.Aluminum was out of the question because the heat from friction would cause aluminum to lose all its strength. So, titanium looked like the right thing to use.
Unfortunately, they had a target of having an altitude over the target of a hundred thousand feet. Archangel 1 could only do about 88 thousand feet. They tried some variations like adding ramjets on the ends of the wings, but that just added weight without adding any more fuel, and it actually shortened the range by several hundred miles. Also, this was not at all a stealthy design. It was a very conventional design. They gave it to the land panel on July 23d of 1958, and because it couldn't hit the target of a hundred thousand feet at, to the middle of its range, they asked Kelly to go back to the drawing board.
So the second design was called Archangel 2. It was similar to Archangel 1. One thing they did, instead of putting the J58 engines right next to the fuze lodge, they moved them out a little bit into enginous cells that were suspended under the wings. The reason for that is when they did the wind tunnel test on the archangel 1 model, they found that there was a vortex of air on each side that came from the point where the wing, which was on top of the fuse lodge, spilled underneath the wing, and it was going right into the inlet of the engine, and there's no way they could keep the engine running, at least at a high speed with that sort of thing. So for Archangel 2, they moved the J58 out. They also left the Ram jets on that they had tried on a couple of the Archangel 1 designs, so they had these big, slender coal cells for ram jets out on the ends of the wing.
This was a really big airplane. It was 129 feet long. It was the biggest one that they went through in their whole design series, getting to what eventually was called a blackbird. They decided they could double the thrust of the ram jets by burning pentaborane, which is known as high energy fuel, HEF, or nick name was Zip. Problem was that was very poisonous, although it did get much higher thrust. This would allow them to increase their mock number cruise from 3 to 3.2. It met all the performance requirements, and it could even maintain a cruise altitude of a hundred thousand feet throughout the entire mission. Not just at the middle of the range, but that would cost about 400 naughtical miles. They would have to spend time climbing to altitude 100 thousand space before they entered denied air space.
Now, in September 1958, the land panel saw this and they rejected it. It was too big, too expensive, pintoborane was a massive problem being as poisonous as it was, and one reason the ram jets were rejected by the land panel is the lack of experience with them. Now Lockheed had actually been using ram jets, typically made by Marquardt they tested them on the outboard edges of the wings P8E drive fighters, and they tested them on a vehicle called the X7 that was used for high speed research. And, so Kelly Johnson had a lot of experience with ram jets, and he added up all the total run time of all the ram jets ever built in America, and it came to seven hours, and so when they were looking to have a pair of ram jets powering a vehicle over denied territory reliably for two hours at a stretch, the experience simply wasn't there. So ram jets were deemed too immature.
And again,Kelly Johnson has now gone into land panel twice in a row with designs that are absolutely unstealthy, big flat wings, straight edges, corners between the horizontal and vertical stabilizers that could reflect radar, and the ram jets themselves as being cylindrical in the cell that gives a good reflection. So, Kelly Johnson had met with the CIA on a Thursday and Friday that weekend in September when he went to a brief land panel. This meeting with the land panel was scheduled for Monday and Tuesday. You see in his notebook that on the Saturday, he started scratching out the design of a much smaller airplane, so apparently when he was at the CIA,he started to get the word that these big airplanes weren't going to fill the bill, even though it was the following week before he actually presented to the land panel. So this was the beginning of the A3 design. At this point, he stopped calling them Archangel just for abbreviation, and it became the A3, and that's what they used in all the succeeding designs is just the letter A.
So, it resulted in a radical downsizing of the aircraft. And so J58 engines, they would try using JT12 turbo jets with afterburners. Those will burn a fuel called JP158. Still, he was gonna try to stick with ram jets on the ends of the wings burning high energy fuel, and the idea was that by making the airplane smaller, he would reduce the cost and the radar cross section. Unfortunately, it turns out that cost in the RCS did not scale down just because this was a smaller design. In fact, all he had done was sort of shoot himself in the foot by having less room for fuel. So it wasn't as stealthy as it needed to be, and the airplane, the A3, didn't have the range. They worked through a number of different designs, and this is the way that Kelly would work. He would sketch out the design in his notebook on graph paper, give that to one of his principle designers, people like Ed Baldwin who I mentioned, Dan Zuck or Henry Cones. And they would comeup with a proper so-called three view, a front, top, and side view of the airplane that could be used to build a model.
Well, each of these guys did their own variations of this airplane. They finally got back together, and what the A3 eventually looked like was a very small airplane. It had a wing. Buried in the middle of the wing were the JT12 engines. The 40 inch ram jets were on the outward edge of each wing, and then there was no horizontal stabilizer. They were trying to avoid that corner where the stabilizer met the horizontal and vertical stabilizers met, because that would give a big reflection. The projected cost per pound of the air frame was pretty high because they were trying all sorts of extremely light weight structural techniques. They wanted to cut weight everywhere they could. They would have minimal instruments. For example, they figured this airplane wasn't going to spend a lot of time in instrument flight conditions, so they didn't need a vertical speed indicator. They would either be coming up or going down. Also, to save weight, they would put ejection seats in, but only for training missions. On the actual operational missions, they would take them out and gain some number of thousand feet by saving a little bit of weight.
Anyway, they evaluated and found that there would be, there was gonna be a significant cost to modify the JT12 for operating at mock 3.2. And, ultimately again, the use of HEF, which was very toxic and, to handle and to use,was another reason not to choose the A3. And they found that they were still going to get a lot of radar back scatter from the ram jet in the cells as well as from the fuse lodge of this airplane.
By the time Kelly Jhonson presented the A3 to the land panel, there was competition. What had been going on in the background is only documented by Frank Rogers in his memoirs. He expressed it as Bissel had a problem with his favorite aircraft designer. Now this is Frank Rogers opinion. He's deceased. So is Richard Bissel, so no one can actually ask them again what the situation really was. But if you look back, in April of 1958, Kelly Johnson began working on a high speed design, getting away from the stealthy subsonic aircraft. And so Archangel 1 and Archangel 2 were not in the least stealthy, and the A3 didn't have it as a very big design requirement. So Bissil decided that what he needed to do to get Kelly focused on stealth was to give him some competition. So what he did was to fly down to Fort Worth to the General Dynamics Convair Division and he saw Bob Widmer the head of their advance development group. He told him that he wanted a reconnaissance aircraft that had a 2000 nautical mile radius could carry a five hundred pound payload and would be invisible to radar. Widmer went to work on this. He appointed a project leader, a guy named Don Kirk. Also working on a this at a high level was Vincent Vincodolsent who was the head of manufacturing research. Now as their starting point for this aircraft they used what they called super hustler. They would redesign that for a minimal radar cross section and what they did while Kelly was working on a number of designs, was they focused on a single design and they defined it in very great detail. So first we have to talk about what the super hustler was. You've probably heard of the B-58 Hustler the first US Mach 2 nuclear bomber, well super hustler was not the B-58 itself. It was a concept for a manned ram jet powered aircraft that could be used in reconnaissance or bombing roles. It had originally come out of the Gebo 2 for generalized bomber concepts that were being developed in the 50s for the Air Force. It could either be carried by a B-58 or launched from a truck or possibly an air craft carrier with rocket assist. It consists of two parts, a man section that was powered mainly by ram jets. It had a pilot and navigator bombardiers. This thing would fly at Mach 4 so it had heat shields over the wind screens at high speed section of flight. It during that time they would have to look out through television cameras but of course it would actually be on instruments most of the time. The inlet for the ram jets was underneath the fuselage so to keep that from getting scraped off on landing the aircraft actually folded down just ahead of the inlets and right behind the cockpit there was a hinge on the bottom surface of the airplane. And the nose would fold down. There was a pair of skids at the rear and a small steerable nose wheel. So the landing gear looked a lot like the X 15 rocket plane. Now attached to that there was a booster section that had a couple of ram jets. So what would happen for example on a bombing mission is either the pair of aircraft would be carried up to altitude on a B-58 the ram jets launched and it would fly in over territory or it like I said could be launched with rocket boost from the ground or from an aircraft carrier. Once over the target the bomb inside the unmanned section would be released and it would fall down along with the unmanned section onto the target and the manned section with the pilot and navigator bombardier would fly back out of enemy territory. Now for a reconnaissance mission the cameras were in the manned section. So they would drop the so called booster section, which in this case they did not have a nuke in it and they would fly back out. Now the original design was not in the least bit stealthy so they had to start redesigning that. They started calling it special purpose super hustler. Now I have to give a lot of credit to Eric Hess the editor of Lockheed Martin's Code 1 magazine in Fort Worth. That part of Lockheed Martin is what used to be Convair in Fort Worth. He was able to uncover all of the documents pertaining to these designs after they had been given up almost for lost for half a century. And he put it on the Code one magazine website. So if any of the listeners want to look into the history of these aircrafts that's a good place to start. But I'll tell you what, I'll give you a verbal summary of what was there. So the special purpose super hustler had instead of the original super hustler it had curved leading wing edge, just like the principle that Frank Rodgers and the other folks from Lincoln Labs and Scientific Institute had come up with. In addition the leading edges of the wing would also have triangular inserts of radar absorbing material. Now you remember that Ed Lubbock of Lockheed had the idea to use those sort of impregnated foam like you would see in an anacodic chamber, well that was marginal for the Mach 3 speeds and temperatures that the Lockheed designs would have had. It was okay for a sub sonic design, however at Mach 4 they had to change material completely. So in that case they used a product called pyro ceram an actual ceramic that was impregnated with graphite. And this was done in such a ways to get a graded impedance across the from the leading edge of this triangle back to the tail. So you had this triangle of this pyro ceram material fit into the triangular cutouts all along the leading and trailing edges of the wing of this new aircraft. They worked through a number of different designs and finally they decided that since Bissl wanted an invisible airplane but his was descendant from the super hustler they would call it the first invisible super hustler or FISH for short. Now what they did was discard the booster stage that I talked about because if you have this manned piece that you're trying to make very stealthy and then you hang another piece off of that with additional ram jets you'll end up with a lot more reflections. So they went down to a single staged vehicle. The launch concept was then to only launch it from under a B-58. The pilot would get in, it would be mounted under the B-58 the pilot would get into FISH, the three crew members would get in the B-58 and they would take off, get it up to altitude like the ram jets on FISH and off it would go. It would then fly back out after taking the photographs of its target. So just to once again hit the main points of this. It had the initial design of FISH that was presented to the land panel in November of 1958. It had stainless steel honeycomb for the wing structure. It had curved leading and trailing edges with pyro ceram wedges in it, and finally like I said the fuselage would fold down for landing. Now what I didn't mention was that there was a small jet engine nestled in the fuselage between the two ram jets. That was to give them a little bit of flexibility on landing. They couldn't get enough thrust out of an engine that would fit in that space in order to be able to actually to do a go around. In other words if the pilot totally screwed up his approach and he couldn't make the runway he wouldn't have enough power to climb back up and try it again. However he would have enough power to stretch out his glide after the ram jets were shut down so he should be able to make it to the airfield.
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