"Paul Suhler Part 2" Avstry #7b
Continuing our conversation, we hear about the B-58 Hustler, the Fish, KingFish, We also discuss the evolution of the A5 - A12 Project as well as details of the SR-71 Blackbird
Published Date: Sun, 09 Sep 2012
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Paul Suhler: 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. So that was the airplane that Widmer presented to the Land Panel in November of 1958 when Kelly Johnson presented the A3. They looked at these designs and they came to the conclusion that further work, both aircrafts were probably feasible and it was worth the government putting in some money. Up until this point both Lockheed and Convair had been using internal research and development funds for these designs they had been doing. But the big shock certainly to Kelly Johnson was that the first choice was FISH. They decided it was definitely better than the A3 on radar cross section and the range and the payload were somewhere better than what Kelly was predicting for the somewhat small A3. So now the land panel asked Kelly to do something. If you recall they had had him do a sort of sanity check on the inflatable airplane designs that the Navy and Goodyear had come up with. So now they asked him to do a sanity check on fish. The idea was to find out were the Convair range and performance numbers all reasonable. And in fact they confirmed the range on Mach 4 performance. But they also found that there were some problems. Ram jet reliability which was no surprise, the lack of a go around capability was negative. There was no way for the pilot to eject when FISH was mated under the B-58. If they had lost a couple of engines on takeoff and then the gear collapsed the pilot down below would certainly be killed. And there were minimal clearances. The nose of FISH actually had to fold back to get out of the way of the nose gear of the B-58 to retract. So there were a number of disadvantages to this. To do this analysis Lockheed actually did two different designs. In December of 58 Dan Zuck designed an aircraft very sharply swept, it was called Aero one. Probably your readers who have read up on the skunk works of this period have seen pictures of Aero hanging in the aniconic chamber. So they did not only aerodynamic analysis but they also did radar models of these. The second aircraft was simply called a B-58 launched vehicle and it was designed by Henry Combs. This one was even stranger because it was a bit longer and so to give clearance for the main gear in the rear the main gear of the B-58 to retract there were actually panels that opened up in the trailing edges of this vehicle's wings. And once the gear the main gear of the B-58 had been pulled up then they would close those panels and accelerate on out. But it was fairly scary. That's one of the examples of what I said about how this was a the clearances were very very tight on mating FISH under the B-58. But overall the concept appeared to be validated exactly as Convair was presenting it. So at this point both groups went back and started redesigning. And sure enough within a day or two of getting the phone call from Bissil that he was coming in second place, Kelly Johnson started to work very seriously on radar cross section reduction. So what happened with the next three designs? They were called of course the A4, A5, and A6. They were all stealthy. They used very light weight structures. Basically they would try to use existing engines that were modified for Mach 3 operation rather than developing an engine completely from scratch. They would use; they would have no horizontal stabilizer, no tail. Vertical surfaces like the vertical stabilizer as much as possible would be hidden behind the wings, so a radar illuminating from below would not see them. And they also began a sort of blended wing and body concept. Now the Lockheed folks derided this as the iron maiden apparently they thought the shape looked a little bit like some sort of medieval torture device. It was actually Frank Rogers's idea or at least he claims credit for it. The way he explained it is you look at the round cylindrical fuselage that you've seen on the earlier designs that is giving big reflections. Pinch that with your fingers on both sides, and stretch it out so it kind of looks like the hole on a high performance speed boat. So you end up with a rounded bottom and then a top that sort of rounds down to that. And frankly if you can imagine that it looks sort of like a slice through of the flying saucer design. So it's kind of a two dimensional version of a three dimensional flying saucer. So the A4 was designed in December 1958. About the same time that designers were working on the FISH comparisons for the land panel. The first A4 design was for some reason called A-4-2. It used a single J 58 engine with an afterburning turbo jet. The vertical tail sides were sloped fifteen degrees on either side to allow bank turns without a reflection being aimed back below the horizon. So that gave the front view of the airplane was rather strange looking because you not just had the blending of the wing and body but in the back you had this really fat tail. Fat at the bottom and tapered up to the top. And the sides of that tail were both sloped in to fifteen degrees. One advantage of that is that it gave them space to put additional fuel. Now because the mid-range altitude was predicted to be 89,000 feet which is below the 100,000 feet that they actually wanted over the target they decided to try adding 34 inch diameter ram jets on the wing tips in addition to the J 58 engine in the fuselage. That actually got them up to 92,000 feet but the problem was they didn't have any extra space for fuel and the extra weight actually ended up cutting their operating radius from 1780 nautical miles down to 1320 so it was a big loss just adding this additional these additional power plants. The next design was the A-5. It looked kind of similar, a very short plane with, more or less, delta wings. The wings blend into the body all the way up to the nose. If you think of what the SR-71 and the A-12 look like with their chines, the A-4 and the A-5 are the earliest appearance of something like that, where they blended the wing into the body and pulled that all the way up to the nose. So the A-5 started out as a simple revision of the A-4 and what they would use instead of primarily of J-58, you would have a single large ramjet in the fuselage and two smaller, JT-12 turbo jets right beside that in the wing roots. The JT-12s would give you takeoff power and initial acceleration up to about Mach 2. Now, hopefully this would allow them to avoid a costly engine development. They realized already J-58 from Pratt & Whitney was going to be fairly expensive to develop so they hoped they'd be able to make this work with the existing JT-12 engine slight modifications. Some of the problems they did find, though, were that the engine compartment tended to be too hot at Mach 3. They could not shut the engines down completely because they needed to be able to take power off an engine to run all the systems of the aircraft, hydraulics, cooling, electronics, and if you have only a ramjet, there's no way to do that. To reduce the takeoff distance and get better acceleration, they added an Aerojet rocket engine that would provide 10,000 pounds of thrust for the first few minutes of the takeoff. This sat up on top of the round fuselage and was kind of buried in the tail. That thing was going to burn 90 percent hydrogen peroxide and the remainder jp fuel. So it was enough different from the A-4 that they just gave it a separate design number of the A-5, but, again, like the A-4, this simply didn't have the range. Again, this Is a small aircraft that had not a whole lot of room to put fuel in. The last of the major small aircraft designs was called the A-6 and they went through at least nine different sub variants of this thing. These used turbo jets and ramjets and various mixtures. This is where you really begin to see a resemblance to what the Blackbird finally looked like. Some of the lessons they learned from doing this though were that stealth and maximum performance, they finally decided, were mutually exclusive because, like the A-4 and the A-5, the A-6 simply couldn't carry enough fuel to make the 2,000 nautical mile radius, and, again, the reliance on ramjets was something they worried about quite a bit. So, at that point, Kelly had kind of given up on stealth. If you read Ben Rich's memoirs, Ben was in charge of propulsion on these projects, Kelly was just about ready to give up. He felt that maybe Convair could give Eisenhower the invisibility that he wanted but he didn't think the Skunk Works could. So what he tried next were three small designs that where not stealthy, the A-7, A-8, and A-9. Now, the general thrust of these series of designs is that they would focus on performance, try to meet the altitude and range requirements at the expense of stealth. What they looked like were very much like Archangel-1 and Archangel-2, just smaller. All three of these design families had a single J-58 turbo jet and two ramjets. They would not use high-energy fuel, the poisonous pentaborane compound known as zip. Instead, it would use JP-150, a high flashpoint hydrocarbon fuel. So there were a number of problems. For example, the A-7, they did A-7-1, -2, and -3, they typically had a poor mission radius, about 1,600 nautical miles instead of the 2,000 they needed. At the middle of the mission the altitude was only 91,500 feet. Although one of the designs in this family was able to get up to 100,000 feet, but they couldn't work out the combination of range and altitude with any of the A-7, A-8, or A-9 designs. So at this point Kelly's designs have sort of come full circle. He's back now with A-10 and A-11 to making a large aircraft. He would just go for performance and range, make no concessions to stealth. Their concept was that this would operate out of the continental United States and could anywhere in the world by refueling, and when they said continental United States they meant Area 51, which is where the U-2 had been tested in secret. They thought that the J-93 engine from GE might be ready before Pratt & Whitney's J-58 so in the A-10 they tried designing around that engine. What both these airplanes looked like were cylindrical fuselage, delta wing, single vertical stabilizer, and the engines were carried underneath the wings. Like I said, the A-10 used the J-93 engine and the A-11, they did versions that had both the J-93 and the J-58. The designer for most of these was Ed Baldwin. So what was going on during all of this time? Because now we've come up to almost the summer of 1959. Well, back at Convair, like I said, they were taking the single design for Fish and they were developing in a great deal of detail. Now the first thing they discovered when they took their initial design and tried running it in a wind tunnel was they had some drag and balance problems. First of all, there was a lot more drag in the mated configuration than they had expected and the B-58A, with its J-79-5 engines wasn't going to have enough thrust to go supersonic. In addition, Fish itself was pretty short and there were some stability issues, so to solve those stability issues they added about a two and a half foot section behind the cockpit, where they can store more fuel, and it stretched out the length of the aircraft, improving the stability. That then ran into problems fitting that underneath the J-58, which is already tight even with the original version of Fish. So they decided that the B-58 itself would have to be stretched by about four or five feet. this turned into what was called the B-58B, also known as the B-58MI for mission improved. In addition to being longer but also used the expected J-79-9 engines that would have higher thrust than the J-79-5 in the B-58s that were currently being shipped to the Air Force. Now with Fish they also made some changes to the propulsion. It still had a couple of ramjets, but you may remember the original design had a single little turbo jet to stretch the landing glide and that was buried down between the ramjets and the back of the fuselage, which made it very difficult to maintain and it caused heating problems. So when they revised Fish they got rid of that and they decided to put a couple of smaller J-85 engines and little pop-out nacelle behind the pilot's compartment. Once they came down out of high-speed flight, these would just simply pop out to the sides and provide, again, enough thrust to stretch the landing glide. Again, not enough thrust to go around so the pilot had to get it right on the first try, had to get the landing right on the first try. As far as stealth, the airplane still had curve leading and trailing edges at the wings. They still put pyroceram wedges in those to absorb radar energy. Whereas the original design of Fish from November of '58 had a couple of vertical stabilizers part way out on the wings, for the June 1959 Fish, the final version, these were pulled up. They grew out of the sides of the fuselage, at the back, near the trailing edge of the wing, and these vertical stabilizers with rudders came straight up from that point. The final cruise number they felt they could get with Fish was Mach 4.2, which is really impressive. Cruise altitude was 90,000 feet. It had a range of 3,900 nautical miles, so they were about 100 nautical miles short of the target, but it was pretty good. they did a lot of studies that showed they could cover any target of interest in either the Soviet Union or China, which were the biggest expanses of denied territory that would have to be crossed. So they felt that this hundred mile drop in the overall range was acceptable. The aircraft was 48 and a half feet long. The wingspan was only 37 feet and was only 9.8 feet tall. Very, very small. The wings and fuselage were not actually stainless steel. They were made of an alloy called René-41. So, in June 1959 the land panel analyzed both the A-11, from Lockheed, and this final version of Fish. They decided that both aircraft could cover all the targets. Both were equal in range and altitude and in sonic boom. Now sonic boom may seem a little strange because Fish was going significantly faster, almost a full Mach number faster than they A-11, but then it was a smaller airplane and was going a bit higher. Fish was a little bit better they said in their analysis documents in radar detection, but because it was at a higher speed it was more vulnerable to being detected by infrared detection gear, but the higher speed meant that Fish was less vulnerable to being intercepted, and, finally, A-11 operation from the U.S. gave better operation security. When you think about it, if you have to take an airplane that's known to everyone in the world, the B-58, to be an atomic bomber, station that on foreign territory just to get it close enough to the Soviet Union or China, and then take off and fly at that nation, how do you know it's not an attack? Obviously this would end up with the Soviets protesting to the host nation that there would be a lot of blowback on that, so for operational reasons like that, Fish was deemed not as good as Lockheed's A-11. Now something else happened at this time, which is the Air Force cancelled the B-58E. Bob Widmer told me that they went on a...people from Convair went to see Curis Lemay, who had been the head of SAC and by then was Vice Chief of Staff of the Air Force. They were trying to sell on the D-58B as a follow on bomber to the B-58A. Widemere gave the pitch. Lemay said that he liked what he saw and he asked, you know, "When can I have some of these?" At that point a retired Air Force General, who had become the President of Convair, named J.T. Mcnarney stood up and fielded the question. He had a lot of money invested in the B-58As that they were cranking, and he said, "General, we can give the B-58B after you've taken three wings of B-58As." Well, that was a bad thing to say because Lemay did not like the B-58A for a range of reasons and various other things. He simply didn't like it. Widemere said that Lemay didn't say a word after Mcnarney said that. He stood up, he walked out the back of the auditorium. A two-star General, probably Shorty Hewitt, took Widemere alone off to his office and said, "Well, that's it. SAC is never going to take another airplane from Convair," and it turned out that that was true. So that was the end of the B-58B, and that left Fish without an aircraft to launch it, so they were pretty well dead in the water at this point, June to July of 1959. The CIA gave Lockheed and Convair instructions to go back and redesign. Lockheed was told to take the A-11, redesign it for reduced radar cross-section, and at this point the agency accepted that they weren't going to be able to get the performance they needed if the aircraft was going to stealthy. So they told Lockheed it was okay to go ahead and make that tradeoff. Convair was told to go out and design a new airplane, try using a pair of J-58 engines and come up with something that can take off only under its own power. So that occupied a fairly short period of time, about six to eight weeks in the summer of 1959. What Lockheed came up with is the airplane that eventually is operating for the CIA. The A-11 became the A-12. Instead of a single vertical stabilizer, they had two vertical stabilizers, one on top of each engine nacelle. Instead of the engines being underneath the wing, they were pulled up and blended into the wing itself. There were radar absorbment material teeth in both the chines and the wing edges. The inlets were axis symmetric, which means that if you look at them from the front they're circular and there's a big cone in them, and this is exactly what you see these days and if you look at a retired Blackbird. And the cost they paid was a 22 percent increase in weight for all of the extra structure to do this blending of the wing and body and all of the weight of the radar absorbent material they had to put in, but that was simply, by now, accepted as the cost of stealth. So Lockheed understood this airplane pretty well and so the A-12 changes were not all that big a deal. On the other hand, Convair had spent about a year working on Fish and suddenly they had to come up with a completely different airplane. So what they initially did was take designs that look kind of like Fish and tried modifying them to stuff in a pair of J-58 engines. But because it was a wholly new airplane, and a bigger one at that, they changed the name to Kingfish. So the initial design looked kind of like a fish. It had a scoop underneath, but it was larger. They used 1/8 scale models and were flying the radar cross-section of this. So as it evolved, the first thing they did was take the inlet off the bottom. They decided what they wanted was a completely flat bottom, or better yet curved, not broken up by any inlets. That would greatly reduce any radar reflection because inlets are always a problem. They tried sticking inlets up on top. They tried a couple of variants with the inlets on top of the wing but to the sides of the fuselage. They continued with a fish-naming motif. One of the inlets was called herring and the other configuration of the inlets was called smelt. They went through a number of different structural designs. Initially, you may recall that I said the design of Fish had the two vertical stabilizers on the sides of the fuselage at the back. They tried turning that into a a V-tail with the bottom of the V, the two tail sections, being in between the exhaust of the two J-58s, which would probably cause a lot of structural weakness. They moved the vertical stabilizers all the way out, or almost all the way out to the wing tips, and they finally settled on having them about two thirds of the way out, but the point was that they had the vertical stabilizers up on to of the wings so that the wings would block a lot of the radar energy from getting to the vertical stabilizers. Also, the ejector of the J-58 engines was what's called a single-ejector ramp nozzle. This nozzle design was extremely advanced for the 1950s. Now, whether they could actually have made the thing work with the radar absorbent material they had to put in is it is unclear. Kelly Johnson thought their inlet design and their ejector design was not believable, and I'm sure he made those views known to the CIA. The final design of Kingfish had performance essentially identical to that of the A-12. It could cruise in Mach 3.2. Cruise altitude began over denied territory at 85,000 feet and it would climb as high as 94,000, and it would have a total range of 3,400 nautical miles, but, again, this is an airplane that could be revealed if it had to be. Propulsion, as I said, was a pair of J-58s with afterburners. It was 73 and a half feet long. The wingspan was 60 feet, and the height was 18.3 feet. If you look at this design, and I urge you to go to the Code One website (http://www.codeonemagazine.com/index.html) and look at it, you'll see that the bottom of the airplane is curved from side to side and from front to rear. It's basically Frank Rogers's saucer shape. Now, I say Frank Rogers, but saucer says that the radar people at Convair, even before they got into this competition for the CIA, they had already discovered this saucer principle, that a curved shape would have minimal radar reflection. As before they had wedges of radar absorbent material in the leading and trailing edges, and, as I mentioned, the single-ejector ramp nozzle with the radar absorbent material, and of course the inlets had radar absorbent material as well. Now, because they were so pressed for time, they needed to get real radar cross section numbers. They didn't have time to build a full-scale model from scratch. They had one for Fish that had been sitting out on a pole being measured at Indian Springs Air Force Base, which is a little bit northwest of Las Vegas. These days it's called Creech Air Force Base. So what they did in the limited time, is to haul that model back to Fort Worth. They stripped the Fish inlet off the bottom. They curved the entire surface, and what they ended up with was about an 80 percent scale Kingfish model. They haul it back out to Indian Springs, put it on the pole, and began doing their measurements. And one thing that came up during this time, this radar measurement facility at Indian Springs had also been used for U-2 models during the time of Project Rainbow. Well one of the engineers from Scientific Engineering Institute, who had gotten into that organization by way of Lincoln Labs, told me that they went to the cafe across the road from the Air Force base and they kind of dropped some hints to see what people had seen, and one of the civilians out said, "Oh, yeah. If you look out there you'll see these airplanes. They come up, they turn around, and then they go back down." So security was a real problem since anybody driving by on a public highway could see the design. Both of these designs, Kingfish and the A-12, went into review again in August of 1959, but they both had the same speed, but the A-12 actually did have a bit better range and altitude than Kingfish. Kingfish was considered riskier for the inlet and ejector designs, also the fact that Convair simply hadn't been working on it very long, and Convair had also had delays on delivery of earlier aircraft and this was something that the analysts in the CIA and the land panel noted. The result was that Lockheed was awarded a four-month initial contract. It started in the middle of September of 1959 and if at the end of those four months, round the end of January of 1960, they could demonstrate significant reductions in radar cross sections, they would be given a go ahead to build a number of aircraft for actual usage. At this point, Project Gusto came to an end. People how didn't need to know that they were actually going to go out and build a real airplane were simply told that they were designs studies that came to nothing, and at this point a new project was opened called Project Oxcart. Why they chose Oxcart? Were they intending to be intentionally misleading, using a slow name for a fast airplane? No one is around who knows anymore. Now there was one of the agency analysts, Jean Keiffer, had looked at these designs. He looked at King Fish, at Fish, at the A-12 and at the A-11 and he felt that they weren't really going to get enough a significant reduction in radar cross section. He recommended to Bisel that they just go with the A-11 and not waste some number of months trying to make the A-12 stealthy, but his advice was not accepted and they forged ahead with the A-12, so over the next three and a half months Lockheed had to prove that they really could deliver reduced radar cross section, so the first thing they did was to build a full scale radar cross section model. The A-12 was going to be about a hundred feet long with a fifty five foot wingspan. What the model was built with a large timber members for structure. These metal fasteners to connect the various wooden parts together, and the entire thing was coated with basically aluminum foil, perhaps a little bit thicker, but it was very thin skin of aluminum. The main thing they wanted was that they would be able to put radar absorbent materials where they need them and then otherwise the shape of the metal would be accurate. Now since they knew they were terrible security problems in Indian Springs, they decided to build a whole new radar cross section facility at Area 51 so several hundred feet North of where the original U2 hangers were at Area 51 in Groom Lake in Nevada, they set up radar equipment and aimed out over the dry lake bed. One mile out they put what was called an elevation post. It was a very large metal pole that was raised hydraulically. It was made I was told by Henry Combs by welding together two propeller shafts from World War II era Destroyers. Now the A-12 model was mounted upside down on top of this. There was a rotator mechanism that was mostly inside the fuselage of the model, and that mounted down onto the top of the pole, so it could be raised and then rotated and also tipped up and down. The analysis of this finally lead to a final configuration of radar absorbent materials. Now I mentioned the wedges of material that they were going to put in the leading and trailing edges of the chimes. They decided that they couldn't have the chimes filled up with these wedges. They needed the space for running electrical and plumbing, so they got away from that and came up with sort of laminated honeycomb panels, kind of like cardboard, except that they were made of asbestos, in the center was a hexagonal honeycomb, like a honeycomb out of a beehive, and then they had flat top and bottom surfaces, and they produced this in sheets, that were roughly about four foot by eight foot, and this replaced the radar absorbent material in the chimes all the way from the nose down to the point where the chimes met the wing, and this opened up the inside of the chimes for putting in various equipment. Now there were other changes made originally the elevons, combined elevator and ailerons, on the aircraft were back, they did not stick back as far back as the end of the fuselage. The fuselage came to a point at the end that was actually a little bit farther behind the end of the engines it selves. The original design didn't have the ailerons going far enough back, but the aerodynamics required that they needed some more space so the ailerons became a bit longer, and went all the way out to be flush with the tail cone of the fuselage. The original design of the A-12 had rudders in a non moving vertical stabilizer. They decided that at, you know ninty to a hundred thousand feet they were going to need more rudder authority, so they went from simple rudders in a vertical stabilizer to all moving rudders, which is what you see in the final Blackbird design. There was one other minor change; the original rudder design had the tail sweeping back. As you look from the side of the aircraft, the top of the rudder was farther back than the bottom of the rudder. Well the changed that. They swept it forward so the top of the trailing edge of the rudder was actually farther ahead than the base. This was also done to reduce the radar cross section, so that was the situation as of the middle of January and Lockheed received approval to continue. Now during this time Converse had gotten a small amount of money to continue with studies on inlets and ejectors, just sort of as a hedge in case something went wrong with Lockheed's design, but as it turned out by the end of January they knew the Lockheed design was going to give radar cross section reduction given a production contract. Now after development of the aircraft started there were a number of other changes. One of the problems was that they knew that radar illuminating the aircraft from the rear would get a big return out of the ejector. The ejector is a big round contraption. It's got basically a lot of hinged surfaces and these would go in and out as the thrust on the engine varies with respect to the outside air pressure. The problem is this looks kind of looking in the end of a can and that will give you a great radar reflections, kind of a corner reflector, so they were actually in one meeting kind of despairing about solving this problem and they thought they were going to just give up on it. In his memoir, Ed Lovick, and this was born out by Kelly Johnson's History of Project Oxcart, he came up with the idea of adding cesium to the fuel. Cesium is a metal that's got the lowest heat of vaporization and by heating this material as the fuel is burned, it produces a cloud of ions in the exhaust, and this would prevent the radar energy from getting into the ejector. Now yes it would reflect a bit but the reflection from these clouds of ions was less than the reflection that we would have gotten out of the ejector, so overall in this a net gain. Like I said this was something that was declassified by the CIA when they declassified the Kelly Johnson's History of Project Oxcart. Now looking from the other end they had a problem with the inlets, apparently a vertically polarized radar beam would couple into the inlet, send electric currents through the fuselage all the way to the back of the engine itself, bounce off the ejector, come back forward and reradiate energy back to the radar, so to cure that they couldn't actually squirt something out in front of the, any physical object out in front of the inlets, so they tried ionizing the air. Westinghouse in her project called Campster built some test apparatus that would shoot electron beams out of the chimes, several feet ahead of the inlets. When the electron beams hit the air that was coming by at two thousand miles an hour, it stripped the electrons off the atoms and produced a cloud of ions, so just like you had in the back you had this big cloud of ionized gas, that would damp out any radar energy, it would reflect it and prevent it mostly from getting to the actual inlets, so again it was a net gain, even though there was a bit of reflection from those clouds of ions, and then finally and it turned out to be very important, there were various electronic countermeasure packages to interfere with acquisition radars, to interfere with targeting radars and terminal guidance radars, and in at least a couple of cases those did save the aircraft, so at this point we are pretty much coming to end of the story. Where things went from, now production approval was granted on January 30th of 1960. Three months later Frank Powers was shot down over the Soviet Union in the U-2, at that point President Eisenhower almost cancelled the project, but they decided that well, since we could not fly these any more over the Soviet Union in peace time, maybe they would be useful in wartime, so they elected to continue with Project Oxcart. Now the first flight originally was projected for a year and a half, sometime in the spring or summer of 1961, but all the problems principally with titanium, but there were other systems problems as well, generally all related to the intense heat, those added a year to the schedule, so it was actually two and a half years, 26th of April of 1962 before the first flight of the A-12 at Groom Lake. Now at that point Fred Whitney was still having problems with the jet 58 engine, so the initial flight for the first, almost a year, were made with J-75s the aircraft couldn't get above about Mach 2, and even that took a dive to get up to speed. They couldn't even hit Mach 2 in level flight, but the first J-58 flight happened in, oh, October, 1962. By January, they had a pair of J-58s that they could put on the prototype aircraft, and in July of 1963, the aircraft finally had its first Mach 3 flight more than a year after the first flight. Then there were a number of other designs. The SR-71 was build by the Air Force. They made their first flight in December of 1964. The Oxcart, the A-12, was finally declared operationally ready in December of 1965 and about a year later, the Bureau of the Budget had been pointing out both the Air Force and the CIA with very similar aircraft and, why do you want both? At the end of 1966 a decision was made that they would terminate Project Oxcart, even before the aircraft had ever been used. In 1967, as the Vietnam war was progressing, there were rumors that the Soviets had installed surface to surface missiles in north Vietnam that could be used to hit any target in south Vietnam. Suddenly finding out if this was actually true became very, very high priority. The SR-71s were not ready at that point. Other reconnaissance aircraft were very much at risk, you know, there were already American pilots in north Vietnamese prisons, so they decided to deploy Oxcart. Three aircraft were flown from Area 51 to Kadena Air Force Base in Okinawa, which you may know is an island at the very southern tip of the Japanese chain of islands, and from there the aircraft could fly over Vietnam and various other countries in southeast and east Asia. The first combat mission actually took place on May 31 of 1967. They continued in operation for about a year, which is how long it took for the SR71s to be ready to take over. Then one of the A-12s was lost on a mission. They had changed an engine, had to go up for a functional flight check, and something went wrong. There were four little bits of telemetry that came back. Possibly the aircraft developed a fuel leak and the airplane exploded, but not trace was ever found of it. The two aircraft that had been part of the mission out of Kadena were flown back to, first, Area 51, and then all of the A-12s were flown to Palmdale and they were put into permanent storage along with lots of engines and various other parts. The final flight of an A-12, flown by Frank Murray, was on June 21 of 1968. The SR-71s continued for another 20 years in service and the actual final flight was by a NASA pilot at the Edwards Air Force Base Air Show in October of 1999. How successful was stealth with the A-12? Well, they were tracked and this is really not very much of a surprise to anyone, but not missiles were actually fired at the aircraft until about the 16th mission late in 1967. There were a couple of near-misses, but there was only one very small hit. One time a missile that exploded behind the airplane apparently threw a small piece of metal out in front. The airplane flew into it, but no one noticed it until it landed back in Kadena and they found a very small hole. That's the only hit that was every scored on any of the Blackbirds. There were a number of aircraft, or design descendants, from the A-12. One I haven't talked about is called the M-21. The Chinese have protested flights by the SR-71 and other aircraft over their territory and an agreement was made that we would not fly anymore manned reconnaissance aircraft. Kelly Johnson had the idea that, "Well, why don't we try an unmanned drone that could fly in, automatically take pictures, and come back out with the cameras?" And this could be a high-speed, stealthy, little drone and they could launch it off the back of a Blackbird. That became known as the D-21 drone. They took the numbers 12 and reversed it. The launch aircraft was very similar to an A-12 except it had additional reinforcement in the back. They called that the strong back modification, and they changed the name to the M-21. So you had the mother 21 and the daughter 21. There were four actual launches of this aircraft. The first flight was at the end of 1964, actually the same day the SR-21 flew. The launches didn't happen for a number of years as they worked through various problems. Unfortunately, on the fourth launch there was a failure in the autopilot inside the D-21. It rolled onto its side, it hit the Blackbird that it has just separated from, and the Blackbird pitched up, broke apart and both crew members ejected but the launch control officer drowned when he landed in the Pacific. Kelly Johnson terminated anymore launches from the M-21 at that point. He said he didn't have Blackbirds or pilots to spare. Instead what they did, they took the D-21, revised it to be launched with a rocket booster. It would be carried up under the wing of a B-58 and launched at the target. They spent a number of years working on this and they were fairly successful. Four missions were launched over China and, unfortunately, they were not successful. The first one apparently suffered a navigation failure and the airplane overflew China and ended up crashing somewhere in Siberia where it was eventually found. The second and third operational missions, the D-21 came back out. The first time though, the airplane that was trying to catch the camera package in midair by snagging its parachute, missed it. The parachute landed the camera package in the water and before the ships could get to it, it sank. The third mission, the Navy actually got a ship to it but the seas were very bad. They got a line on the camera package, unfortunately, they hauled it underneath the ship and it was destroyed. The fourth launch was a mystery for many years, then about a year and a half ago, pictures of the wreckage of a D-21 started showing up on Chinese websites. It turned out the thing had suffered a system failure, crashed in the forest. It was eventually found by the Chinese army and the fragments today are in a Chinese aviation museum. So that was the M-21. There were a number of interceptor variations with different names. The one that actually got built was the YF-12A. They built three prototype Interceptors. They used a Hughes radar and air-to-air missile system. It was at the time called the GAR-9 missile and the ANASG-18 radar. These were originally tested on a B-58 flown by civilian test pilots working for Convair. One of these, Jimmy Easton, was hired into the Skunk Works because of this, because of his knowledge of that program, and eventually that weapons system was integrated into a Blackbird called the YF-12. The Air Force started to buy 92 of these, which would've been a huge amount of business for the Skunk Works, far more than anything they had every produced on any of their, basically, boutique production of aircraft, but that was cancelled and so in the end there were only the three YF-12s. One was damaged due to over temperature and all of its wiring had to be stripped out. It was wasn't worth salvaging. Another one actually crashed after a fire. The crew got out okay. And the third one was finally flown to the Air Force Museum in about 1976. It had been used by both the Air Force and NASA for testing, and it's the one YF-12 can be seen today at Wright-Patterson Air Force Base at the National Museum of the Air Force. There were some further designs for that. The one that would've been produced for the Air Force, produced in quantity, was called the F-12B, but it never made it to production. Now, in the reconnaissance line there was a reconnaissance bomber variant called the RB-12. They worked through, not just reconnaissance like I said, but there were three different bomber designs. They tried putting a large nuke inside the fuselage. They tried putting smaller nukes in the chines, which is where the YF-23 had had kept its missiles, and then they even tried a rotary bomb dispenser inside the fuselage, but the Air Force never decided to buy any of those. They continued with the reconnaissance designs. They come up with something called the RS-12, then finally the R-12, and that's the design that was eventually bought by the Air Force as the SR-71. There is a story that's been going around for many years. A lot of people in the Skunk Works had believed this story, that when Lyndon Johnson announced the existence of the SR-71 in 1964, that it was really called the RS-71 and Johnson had misread his script. A researcher at the LBJ Library has dug up the original scripts that Johnson read, and he dug up the transcripts that a transcription service made from recordings of the press conference. The original script said SR-71. The transcribers got it wrong. They wrote down RS-71, so when the transcripts were released, everyone thought that Lyndon Johnson made a mistake when, in fact, he had not. Now there is still a mystery as to where did the name SR-71 come from, because in a phone conversation about two hours before the press conference you can hear Robert McNamara, the Secretary of Defense, referring to it as the R-12. Apparently, Curtis Lemay, as far as anyone can tell, is the source of naming the aircraft the SR-71. One of the missions for the B-70 was a so-called reconnaissance strike, and that was called the RS-70. It was a version of the B-70 that of course was never built because only the two experimental prototypes of the B-70 were built. So this was apparently intended to follow that so they gave it the number 71. SR, strategic reconnaissance perhaps, but that's still a little bit of a mystery that's never been solved, and of course all the research in stealth eventually gave Lockheed an advantage. They were able to get in, in the 1970s, into a DARPA competition to design a stealth test bed aircraft. Originally they weren't even invited to participate because no one knew about their experience in stealth. They were sort of working toward fighters and they didn't feel that Lockheed had built enough fighters recently. once Lockheed found out about this they got permission from the CIA to talk about what they had done on the A12 program, and revealed at least to some people that the Blackbird was actually intended to be a stealth aircraft.
Lockheed won the competition. They built two of what were called the half two prototypes for about 10 million dollars a piece. And that wont them the contract to build the F117. So, in some sense, that's also a descendant of the Blackbird. So to wrap up I'd like to talk about how it was possible to do this kind of development. the first thing was there was an urgent national need. Critical intelligence was required. The most important thing they needed to know in the mid 1950's were the capabilities and intentions of the Soviets for launching an attack on the United States.
The U2 revealed that they didn't have the capability. They didn't have enough missiles or bombers but it was worthwhile to know that. The next thing it took besides an intense need, was some visionary individuals. both in government and in industry. These people had to be able to tolerate failures knowing that if they kept at it long enough they would be successful. An example from another program would be Corona, the original spy satellites. Eisenhower, you know, saw a string of failures. There were twelve failures to get a satellite into orbit and back again. twelve failures in a row.
And he said keep working at it. He was prepared to accept that it was gonna take a lot of money and a lot of time to make this work. So there was also willingness to take risks. You know, both on the part of the government customer and on the part of the contractor. That required a lot of trust between the customer and the contractor. In the case of the Blackbird, the key people were Richard Bissel and the CIA. Kelly Johnson at Lockheed. And the air force supporting the CIA was a Lieutenant kernel named Leo Gary. These people knew each other very well from the U2 program, and they understood how they could work together.
The next point was that all of this had to be done in absolute secrecy. That required that there were a minimum number of people aware of what was going on. now that had other effects too because that kind of minimized the paperwork. Henry Combs, one of Kellys principal designers, has a rule of thumb that for every person that the customer, the government has looking at the program, you need a full time engineer to keep that person with enough information. Well if that person is busy talking to the customer, he's not able to work on the design.
So, if you have a minimum amount of oversight. You reduce the paperwork and you allow a relatively small number of engineers to get the job done in a quick time. There was also a lot of individual responsibility and accountability at the level of the engineers and the skunk works. One of the junior people in the structures group, he had the least experience of anyone in the structures group, he was 33 years old. and he's already been in the aerospace industry for 10 years when he was brought into the program.
The next least experienced guy was 40 and had, you know, even more years of experience. So these are people that didn't need to go to their boss for small decisions. They were capable of making decisions on their own. and that again sped things up. And the final bit and why it was possible, is cradle to grave ownership of the design. For the CIA, Lockheed did all the maintenance. The other contractors, the, you know, engines, electronics, they would send their technical representatives out to work on your aircraft at Kadena. They did not have to train CIA maintenance people.
Now the air force didn't go for that. they wanted air force mechanics actually working on the aircraft. But still the Lockheed and Pratt and Whitney, technical representatives, even with the SR71, were crucial. So I'll just conclude by quoting Kelly Johnson. " Be quick, be quiet, and be on time." Usually they were all of those three, sometimes they were not as fast as they wanted. but the result was an amazing aircraft that will probably be known as long as this country is known. So thank you very much for listening. Would you like to give me some questions?
J.R. Warmkessel: Yeah. I have some questions for you Paul. You talked a lot about Ram Jets. Just for the listeners that maybe aren't familiar with what a Ram Jet is, could you give a brief overview of what a Ram Jet is?
Paul Suhler: OK. Well, let me start by explaining what a Turbo Jet is. A Turbo Jet has inside the cylindrical structure, it's got a number of compressors. It's basically a bunch of fans at the beginning of the engine that suck air in. now behind those compressors is a chamber where you add fuel and you burn the fuel and it blows out even faster through another set of fans that are spun by the gas, the burning gas coming out. Those are used to turn the compressor blades up front. So you've got a lot of structure inside the engine.
A Ram Jet on the other hand, is really not a whole lot more than a cylinder of metal. Up front it'll have a spike that's used to compress the air as it comes in. And then there may be a very slight structure called a flame holder where the fuel is actually injected into the stream of air. but it has an advantage of generally being able to work at higher speeds than a Turbo Jet. Turbo Jet you have to get the air down to a relatively low speed. And it's also a lot heavier. The Ram Jets have very little structure so they're much lighter.
So, just think of it kind of like a stove pipe with air coming in the front and being compressed, squirt in some fuel and it blows out the back and provides you thrust from all the other burned fuel going out. So, that's a quick summary of what a Ram Jet is and how it differs from a Turbo Jet.
J.R. Warmkessel: Could you maybe highlight some of the differences between the the Oxcart project and the SR71, I mean from an aircraft point of view?
Paul Suhler: Uh, sure. The first thing is that the Air Force One had a two man crew. So, instead of having a big camera sitting behind the pilot as you did in the A12, you had a reconnaissance systems operator in his own cockpit. he could look out the sides, of course he could not look forward. He could operate to some degree the auto pilot, but more importantly he operated the radios and the connaissance equipment and the electronic counter measures gear. Now the cameras for the SR, instead of having one giant camera which I had been the way Oxcart was done and it was the way the U2 had been done.
There were smaller cameras that went generally in the chimes. There were some other pieces of equipment designed. one was a synthetic aperture radar, in which they had a radar energy can be transmitted from I believe generally the nose of the aircraft, out sideways. And it would be pulsed as the airplane flew along, and then received in through all of these mini reflections. As the aircraft moved they would record all the data, run it through computers and come up with actual images of what the targets looked like.
Obviously if you're running something like that you're not stealthy, but then you would use it in cases where people knew you were coming anyway. OK. So that's kind of it for the nose of the airplane. Now they found a, you may remember I mentioned that the elevons of the 812 were flushed with the end of the tail cone on the fuselage. It turned out there was a lot of drag. they called it boat tail drag. and in the SR the they extended the fuselage by five or six feet aft. So, if you look at the tail cone of the SR71 it actually sticks out a couple of feet behind the elevators, or rather the elevons.
That also gave additional space for fuel and additional space for equipment. So those are the most obvious differences. As far as performance, the SR with the second pilot and longer fuselage was a bit heavier and it couldn't go quite as high as the A12. but those otherwise their performance was very similar. Now someone once asked Bill Park, who was the second person to fly the A12, what was the actual fastest the thing ever went. And he wasn't sure and he didn't think it was really a very useful question. he said it was hard enough to get the airplane to fly straight and level at the design altitude, far enough, do 180 degree turn without losing altitude, and come back. Which was what they had to demonstrate for the CIA to give them their final payments.
So, typically the SR's were operated at not more than about a mach 3.2, all though when missiles are fired they could accelerate beyond that. The fastest documented speed I've heard of is Mach 3.5 during Operation El Dorado Canyon over Libya in the 1980s. But the A-12s probably went a bit faster than that. But again, the documentation on that is kind of weak. So those are the main designs. It was bigger and heavier and had a second pilot and it had a reorganization of the reconnaissance equipment, it was put into different places.
J.R. Warmkessel: One of the other things that I was told, and maybe it's a urban legend, was that the SR-71 would take off with minimal fuel because when it was cold all the fuel would leak out of it, and then as the airplane flew it would warm up and it would expand. Is that true to your knowledge?
Paul Suhler: Yes, that's absolutely true. They tried, for years, trying to find a good tank sealant that they could, you know, a sort of putty-like material that you could go inside the fuel tanks and apply to all the cracks that would last through starting off at the ground, climbing up, taking on very, very cold fuel from a tanker, then heating up to temperatures almost approaching 1,000 degrees at some points on the fuselage, and then land again. They never did find a good tank sealant. They eventually gave up on it, because they found that all of the pieces fit together very tightly when they were at high speed. So for most of the flight when they were running very hot, there was no leakage. But you would see fuel leaking out during refueling and certainly on the ground it would drip out. Fortunately this was very high flash point fuel. It had to have a very high temperature to be lit. They had to do that to avoid a risk of fires at high speeds. Now in addition they also had nitrogen that they would pump into the fuel tanks to take the place of fuel as it was burned out, so they wouldn't actually have oxygen in contact with the fuel. Also what that meant though, with this high flash point, is they needed a very special ignition system. What they used was a material called, I believe, triethylborane, which would burst into flame on contact with air. They had small containers of this, and you could get, I believe, 16 lights with this, and they would use it to light the afterburners, and of course they would use it to start the engines on the ground. So when the aircraft would finish refueling and was ready to start its climb back up, the pilot would put the aircraft into afterburner, that would automatically give a burst of TEB into the exhaust stream, and that would light off the fuel as it was going through the afterburner. One of the limits on the number of refuelings you could do was the number of shots of TEB they had. So yes, fuel was a tremendous problem, as was preventing the leaks, and they eventually just had to give up on trying to control leaks on the ground. But like I say, fortunately the stuff had a real high flash point and it didn't really present a fire hazard for an aircraft sitting in a hangar.
J.R. Warmkessel: And did I also hear that the aircraft grew about 11 inches from its cold resting weight to when it landed from one of its missions?
Paul Suhler: I don't know exactly what the real number is. Most of the numbers I've heard were about six inches. But yes, it did grow significantly. There were other stories of, you know, wrinkles would appear, for example, in the nose ahead of the pilot. In one case a pilot who was on one of his first high speed flights thought the nose was coming off. He did an emergency return to base and they explained to him, no, this is, that's what you will see. And the maintenance people would just use a blowtorch to smooth out the skin again. Now that did cause other problems that they had to solve during the design of the airplane. The wing, the wing panels would expand, and at first they were tearing lose from their welds on the internal structure of the wings. Kelly apparently was the person who came up with the idea to put corrugations running from front to rear very slight indentations, you know, little grooves, they looked like. So what happened instead of having a flat sheet that was expanding sideways and ripping loose all of its weld points, as the titanium expanded, the corrugations just got a little bit deeper, and then as it cooled off they got a little bit shallower, and it reduced the stress on the welds. So yet another instance of all the problems they had with heat in the aircraft.
J.R. Warmkessel: One of the other things that I was always curious about was the radar testing that you talked about. It seems like the computer options, the computer power options, would have been almost nonexistent in the late '50s, early '60s. So how would they have tested these different models at these different testing ranges?
Paul Suhler: When you look at some of the early documents that the agency has released on Project Rainbow, you'll see things like strip chart records. What a strip chart is, is exactly that, it's a little recorder that's marking on a strip of paper as it reels past. So what they would do is that they'd have a radar unit that was broadcasting at the model, and then receiving the reflections, and that signal that came back was just turned into a squiggle on this line of paper, you know, where this was from left to right along the paper indicated how strong the signal was that was coming back. And then this little paper was wound up on a reel and would just be fed through this recorder. So at the end of the day they would have, someone would have to be sitting at this thing and mark it when they were aimed exactly at the nose of the aircraft, or exactly on the side, or exactly at the rear. They'd have to keep track of whether they were measuring it sort of head-on, or with the aircraft tipped up some number of degrees. So there was a lot of handwork, because they would have to go through all these strip chart recordings and make measurements and determine what the actual intensity of received radar beam was. And at first it was very, very much a manual process. Now they tried automating that, they used the one and only instance of a computer originally designed by Digital Equipment Corporation, and this was called a PDP-3. It was designed originally for the Navy. The Navy decided not to build it, but somehow the people at Scientific Engineering Institute got hold of the spec and they decided they would build one. Well it was like the worst imaginable homebrew electronics project you could come up with. They knew they needed this computer to process all the radar data being taken on the A-12 at Area 51, but they couldn't resist tweaking the design all the time, and basically they said that in order for someone to actually run the program that would analyze the radar data, they had to have one of the three people that helped build the machine with them to hold their hand as they walked through it. It was not at all easy to use. They had to do that because the computations of translating so much radar energy into so many decibels of signal strength were just taking way too long. So they were able to automate it to a certain degree. I'm sure these days radar ranges that are used are very, very highly automated and they produce data straight to a computer, because you don't have to go through the stage of paper the way they did back in the '50s and '60s. So yes, it was initially an extremely manual process and it became somewhat less manual when they were able to get some computer support.
J.R. Warmkessel: One more question with regard to the supersonic requirement of the aircraft. When we look at the modern stealth aircraft, up until very recently they were subsonic aircraft.
Paul Suhler: Right.
J.R. Warmkessel: Why did the military or the CIA feel that they needed an aircraft to fly super high, super fast, and be stealthy? Wouldn't just being stealthy would have been enough?
Paul Suhler: They were trying to hedge their bets on all three fronts. Remember I mentioned that so-called blip scan study, where they came up with the 90,000 foot altitude, and the Mach 3 speed, and the radar cross-section maximum amount. By putting the aircraft as high as they could, they would reduce the radar signal strength from the echo being returned because it was simply farther away from the radar. Also to fly really fast you need to be at a higher speed so that kind of went along with that. But the speed itself was important because that would mean that the aircraft would be scanned by radar fewer times. Remember, they were hoping that a human who was staring hour after hour at this radar scope would actually miss the blips. So they just wanted to make the blips as faint as possible and as few and far apart as possible. So the requirements all sort of worked together, of altitude and speed and radar cross-section. Does that answer your question?
J.R. Warmkessel: Yeah, it sure does. Paul, is there anything else I should ask you about while I have you here on the phone?
Paul Suhler: Probably, but we could stay here some number of more hours. There are any number of stories that I've heard over the years as I've worked on this book, some you'll find in other sources, some in my book, and I guess I'd like to put in a pitch for a couple of books the listeners might want to look at. The first was Kelly Johnson's memoirs published by the Smithsonian Press. It was called Kelly: More Than My Share of It All. Now, this was the first one to come out, and it's actually lacking in a lot of technical details. He was still being very careful about what he was saying. I believe that book was published in the '80s, because Kelly Johnson died at the age of 80 in 1990, so some time during the 1980s that book came out. The next one by a Skunk Works alumnus to come out was Skunk Works by Ben Rich. He succeeded Kelly Johnson as the head of the Skunk Works. He had first joined them to do the inlets of the U-2, and he stayed all the way through the F-117 and then some more work beyond that. In the last couple of years, Edward Lovick has produced his own book called Radar Man, which he self-published, I believe through iUniverse. He gives even more details about the work on stealth and various other things. He was with Lockheed for a number of years before he joined the Skunk Works to work on the U-2, so he has a lot of very interesting stories from the early days. So those are some things your listeners might want to go take a look at.
J.R. Warmkessel: And we would also like to talk about your book, maybe where our listeners could find it and purchase it.
Paul Suhler: You can get it from Amazon.com. Fortunately AIAA priced it at $40. If any of your listeners happen to be members of the American Institute of Aeronautics and Astronautics they can get copies at, I think, 25 percent off through the AIAA web site. But it's available at all the usual places."
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