"Alan Brown Part 3" Avstry #3c
Alan Brown, of the Lockheed Skunk Works continues with more stories working with Ben Rich on the F-117 Nighthawk, why it's the shape it is, how it got it's name, and why it's black.
Published Date: Fri, 29 Jun 2012
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J.R. Warmkessel: Can I ask you to rattle them off if you remember them?
Alan Brown: Oh, all kinds of things, mainly concerned with simplicity of operation. And also, for instance, don't walk into a contract and feel that you have to obey every one of the Air Force's normal contract requirements. Insist on starting the contract listing the requirements as needed for the contract, rather than just taking the five-foot shelf of books out of the library that says all what the Air Force has done in the past. So that was one of them. Another one is that people should be rewarded not based on the number of people they supervise. Quite the contrary. If you can show that you can get by with half the size of team that would be considered normal, We'll give you a big raise in pay. Because his view was the smaller the team that produces something, the better it would be. If you go back to the P-80, which was a single engine airplane that he made during World War II, and he produced that airplane not in the 180 days he promised, but in 143 days, from putting pencil on paper to first flight, which was amazing. And the picture of the airplane, which I have, which shows the photo of the prototype airplane, and round the photo are the signatures of the entire design team, and I think there's about 30 people. Nowadays it runs into hundreds, you know, so it's just, he was very keen on minimizing paperwork, having a very close cooperative operation with the customer. Do not hide things. You know, Ben Rich used to say to me good news should get to the top as quickly as possible, and bad news even faster than that. So that was something that I did, followed, as a program manager and was later complimented by the Air Force program manager as being a very easy, good person to work with. Because as far as I was concerned, I was program manager of the F-117. This was going to be a very difficult airplane. We would be concentrating on stealth, we'd be concentrating on airplane stability and control, because the airplane was basically unstable in all three axes at some point of its flight envelope, which was totally new. And in addition to that we wanted to be sure that we didn't trip up on something else. So because we had these two very big problems, I and my two assistant project engineers, who were both very experienced, Bill Taylor and Ed Baldwin, insisted that the airplane be as conservative as possible. For instance, we did not introduce composites, although composites were just coming in at that time. Mercifully that was a good decision because composites took a very long time to realize their potential. We stole things from other airplanes wherever possible. Landing gear was Gulfstream 4, I think. The navigation system came from a B-52. Heads up display and major glass panel instruments from the F-18. The basic stability and control calculations, computer situation, came from the F-16 program, which in turn used Lear Siegler to develop them, so we did the same. We took the F-16 program and essentially put our aerodynamics into their program. So in every case on the airplane, on the 117, we didn't invent anything that had already been invented. We were having a tough enough problem with stealth and stability that we didn't want to mess with anything else. Plus, we were very fortunate we had a very small Air Force guidance group, oversight committee, of only seven people, all of whom, or pretty much all of them, were Air Force civilians out of Wright Field, experts in their particular technical fields. So those seven people worked very well with our counterparts at Lockheed and we had a very good one-on-one set of relationships there. By contrast, the F-22, which was a very complicated multi-company airplane with a huge organization chart, as you can imagine, Lockheed, Boeing, General Dynamics, and the Air Force had all sorts of ideas about, you know, the way in which this whole thing was layered, totally different from a Skunk Works approach. The Air Force team in the F-22, contrasted with our seven, was 130.
J.R. Warmkessel: So one of the things I noticed about the F-22 is that it's very smooth, as opposed to the 117, which is very angular.
Alan Brown: Right, okay. First of all, you've got to figure out why the F-117 is the shape that it is. And that's not, it is sort of technical, but not completely. And that is that when we did the Have Blue there was a question as to how you determine in competition which airplane has the lowest radar cross-section. Because you're looking at a bunch of frequencies covering a frequency range of 100 to 1, like a very good stereo hi-fi system. You're looking at a variety of azimuth and elevation angles on the airplane, and so there are literally hundreds of different points where you can get a radar measurement, which is quite different from a speed contest, where you just fly and who goes fastest wins. So a guy called Nick Damascus was brought in from one of the Pennsylvania universities, I think the University of Pennsylvania. He previously worked for Darpa as a consultant on the SR-71. Very bright electromagnetics professor. So Nick came up with a magic equation with a single number at the end of it. He divided the airplane into 45 degree sectors so there was a front sector which was 45 degrees because your biggest signal comes in-you're looking at right angles to these edges and you'd like all the signals to be in the side sector and none of them to be front and back, which is exactly how it worked out, so we won the competition by doing that. Now, so that was basically, you know, how the F-117 got started and when we got the contract for the F-117, although we were told that they wanted us to make this military airplane, the Have Blue had been made all in flat panels, and the main reason it was in flat panels is because that was what our computation was capable of analyzing. We couldn't analyze curved surfaces in the '70s. So we did the flat panel approach and I said well, when we get to a real airplane, you know, the Have Blue XST airplane was essentially designed and built to be like a race car. It only had one hour's worth of fuel. It wasn't designed for anything else. It carried one pilot. It wasn't very big. It was only 22 foot wingspan, so, you know, if we make a military airplane, which is clearly going to be a lot bigger, it's going to take, say, 5,000 pounds of weapons, it's going to travel 600 miles range, you really want to try and get a better aerodynamic range payload capability than the Blue, because the Have Blue was just designed to win a race. So the feeling at the Air Force then was, they weren't quite sure whether we'd just been lucky or not, and so they said, "Well, we don't want you to depart. We want you to make your airplane, the military one, just a scaled up version of Have Blue," and I said, "Well that's going to be a disaster because it's got such a low aspect ratio, it just-we'd never get the range payload we wanted to a conventional mission." So they did allow us to relax a little bit, so we moved the sweepback angle from 72 degrees to 67-and-a-half, which doesn't sound much, but it does make a big difference to the aspect ration of the airplane, and aspect ratio is a major player in the range payload equation. So we did get that, but we-I said that also we can improve the aerodynamics by replacing the wing, which is a hexagon section, because they're all flat panels with sharp edges. We've got to keep the sharp edges around the perimeter for low radar cross section, but we can certainly go from a hexagon section to a bi-convect section, which is just to arcs of circles which would be more efficient. We could also round off the tope of the fuselage, and that would be better. Then you wouldn't get diffraction terms coming back at you. I said, "If you did that, we'd improve the aerodynamics of the airplane and we'd get a lower radar cross-section because we wouldn't get diffraction terms coming back from the sharp edges," but I said, "Unfortunately, we wouldn't be able to calculate it because we haven't got the capability of going past that panel." So they said, "Don't take any chances." You know, they were just sure that we'd, you know, we'd been very lucky that we'd got the shape we had, don't depart from it very much. So the F-117 essentially has the shape it has because Nick Damascus came up with 45 degree sectors in the XST competition, and so that's the major reason why it finished up with 48 degree sweepback on the wings and exhaust nozzles.
J.R. Warmkessel: Interesting story. Tell me, why is it called the F-117? It's a bomber.
Alan Brown: Oh, okay. That's very easy. The airplane, of course, because it's-first of all, when it was first, when the XST was first flown, we had two pilots. We had a Lockheed pilot, Bill Park, who was our chief test-pilot of the Skunk Works, and we had an Air Force pilot who also flew the airplane, and the Air Force pilot, of course, was a very competent flier and the people who went-as soon as we got to where it was going to be a military version, we were going to get the top Air Force pilots to fly the airplane. Doing that, the top pilots, of course, would be considered to be in tactical air command, and the guy who was picked to be the first squadron leader of the first production package of airplanes was "Burner" Bob Jackson, who was the leader of the Air Force Thunderbird aerobatic team. He was the top tach pilot. He was given the job without being told what it was, but, you know, guaranteed it's the most fun job you could ever have, so of course he volunteered for it. Bob Dixon, the four-star in charge of tach was the one who gave him the job, and all the other people who were recruited were recruited by Bob Jackson from Tactical Air Command from all his top pilots, and he would just tell them, "We got a great program. I can't tell you anything about it. You'll love it. Do you want to join?" They, "Absolutely." You know, if it's the top thing in the Air Force, and Bob Jackson's running it, absolutely. So, of course, these are all fighter pilots. Now, fighter pilots, it's well known, very proud of what they do. They are not people who fly bombers. They do not fly B airplanes. They don't even like to fly attack airplanes, A airplanes. They are fighter pilots. The consequence is that when the airplane got a name and a number, there was no way that you could make that other than an F, just because of the people who were flying it, not because of the job it did, although it is capable of getting it out of its own way. It is a 6G airplane, which is not as much as the 9 or 10 Gs of an F-16, but it's still better than a Boeing 747, so the airplane is capable. The Air Force pilot who first flew the Have Blue airplane was Ken Dyson, who later of course became a, when he retired from the Air Force, became a civilian test pilot and worked with both Lockheed, and Northrop, and Rock, North American Rockwell later. He was a very good pilot and, as were all the people who were on that program.
J.R. Warmkessel: Tell me about the color of the aircraft.
Alan Brown: Okay. The airplane, of course, first of all, was designed to just fly at night because it was recognized that although it would have a very low radar cross-section, and it was also designed to have a low acoustic signature, which meant a suppressed noise signal from the engine, and also a low infrared signature by hiding the exhaust nozzle fairly well from the ground, so it was recognized that it would be visible in the air. In other words, it probably would be seen visibly before it would be picked up by any of the other more advanced systems like radar and infrared, and so clearly that was a good argument for flying at night, so decided we would fly at night only. We worked with a small company run by a guy who had worked at Cornell Aero Labs on visual signature, and this was-we based the color design that we came up with on optimizing the airplane for the altitude at which it would be flying, which was about 15,000 feet, and recognizing that most nights are not black outside. There's stars and there's moon and there's all kinds of reflected lights, even if you're working in complete blackout situations as far as town, cities are concerned, there's still enough ambient light from the sky that you want a very specific color scheme.
And it's very interesting or it was to me because I was in charge of not just radar, but all observables, so I was involved in the visual as well as acoustics and infrared and radar. It was very interesting to me to find out that what you, what you see is not the color that things really are. I mean this dates back to the Expressionists of the, the French Expressionists of the 19th century who started to understand that.
And I good example is that the U-2 airplanes were always painted black and the reason they were painted black is not because of the fluid night predominantly was because they flew at very high altitude where the air is to thin that it's very difficult to get rid of the heat generated within the airplane from all the electronics that they carry.
And so you paint a matte black to get maximum radiative capability because you've got an emissivity as close to "1" as you can get. So the U-2s were black, not because of flying at night, but to keep them cool as possible.
The flight test people on the 117, Keith Beswick, told me that when he used to follow the f--the U-2 flights and they would follow them up as high as they could, even though the U-2 was black, eventually it got high enough that there was enough reflected light from the rest of the sky below it from dust in the sky from the earth, and there was less light above, the sky gradually turned black, that there's a point where the black U-2 actually became lighter than the sky background. And that's unbelievable, you know. Most people would think--I mean this airplane was painted as matte black emissivity "1" as you know how to do it.
You know, absolutely zero reflection, and yet the U-2 stands out as a lighter colored object, starts looking white compared to the black sky behind it.
So often people don't recognize this, so we actually designed a color scheme based on this guy with Cornell who had done a lot of work on it. And it was in multiple shades of grey with the lightest color on the bottom and the darkest color on top and intermediate colors, depending on the slope of the sides. And that would result in the--when the airplane is seen at a distance, when you first see it as a dot you want to minimize the distance at which that dot first appears.
So you aren't really interested in the sort of WWII kind of camouflage schemes. You're interested in the difference between the airplane and the background. That's all you care about. So if you do it multi colors, depending on the light that's shining on it from wherever, which may be the moon, stars, whatever, or sun--you want to make it so at a different altitudes you would paint it different colors slightly.
So we had that all figured out and our same general, Bob Dixon, who was a classic Air Force fighter pilot, he was of course, in Vietnam. He'd had many thousands of hours as a fighter pilot before he eventually became four star, but he was always you know, white silk scarf. He smoked through a cigarette holder. His hat was always at the right angle on his head, very good looking man. I mean he was just incredible.
But he was--we had two models on the desk in my office. We had the one painted these multiple shades of grey and it wasn't camouflaged, it was just different shades, depending on what the angle was. So it would be uniform on the bottom, uniform on the top of the wings, etc.
And then we had the one that was just all black. And he looked at the two airplanes and he was obviously not impressed with these shades of grey. He said Brown, he said trainers are painted white. I'm not gonna ask any of my pilots to fly one of your goddam pastel grey airplanes. He said this airplane is gonna fly at night, isn't it? He said well paint the goddam thing black.
So that was the entire technical input on the color of the airplane. Later it turned out that Wright Patterson Air Force Base people said that they did some tests comparing the black airplane with the grey airplane with models and the black airplane won. I said well how did it win?
He said well first of all we looked at the airplanes in the dark and it turned out that their dark, they didn't go outside at night, they just went inside a totally dark room which had no windows, turned all the lights off, so clearly you couldn't see either airplane.
Then they got flashlights out and shown flashlights pretending they were searchlights and said they could pick up the grey airplane easier than the black one. And I said well you never tested it outside.
Well, no, no we didn't. So anyway, so that was the extent of the visual kind of large scheme.
J.R. Warmkessel: So as the project manager, I understand that a number of these aircraft were lost in combat.
Alan Brown: Not a number, one, one was lost in combat.
J.R. Warmkessel: Can you tell us why?
Alan Brown: Yeah, I'll tell you also, I'll tell you the story about what the airplane was finally taken off the top secret list and that was because as the number of airplanes increased, by the mid 80s we built almost 60 airplanes and the cadre of pilots flying them is now a larger group, much larger group, the initial very top level pilots that they had. And on two occasions it's not clear to me when the air force did this. They were flying the airplanes, four of them together in formation at low level. And two pilots in separate occasions actually just drove the airplane into the ground; one of them almost drove it into like just throwing a javelin into the ground. And he just got completely mis-oriented flying at night and just drove it, drove it out, drove it down.
So that was when the air force decided better start flying during the day. The consequence of that was that they expected to get lots of people calling in about UFOs and whatever, so the airplane was officially released by the air force.
My own experience with that was in 1988, in November of that year, at that time the airplane had been flying for seven years or more than seven years. The first flight was in July of 1981. So we had been flying for a long time and it had been a very well kept secret.
And I'm on vacation with my same friend, Leo Selnica, I mentioned earlier, and two wives in South America. And I'm on a little commercial airplane flying from Iguazu Falls on the Brazilian-Argentine border to Rio de Janeiro.
And I just happened to pick up a newspaper in Portuguese that was just lying on the seat, turned to page 3 and there's a picture of my airplane. And I thought oh, shit, you know, what is going on here? I better tell the consulate when I get to Rio.
Well it turned out when we got to Rio it was on television and the US Air Force had made the announcement of the existence of the airplane. So that was my first understanding of it.
But that was, so we lost two airplanes in Air Force pilots just flying over California and Nevada, just for different reasons associated with just the pilot going disoriented.
Another airplane that we lost, and this really upset me, was after the airplane was released to the general public and after the first Gulf war in 1991, the F-117 was seen in the Air Force flying displays. And on one of those displays, the airplane lost, had an aileron break off the wing and the airplane crashed. It turned out that in the airplane had undergone a major maintenance the previous January but had never flown in the high G levels in the demonstration-aerobatic flying until the summer and when the aileron had been put back, all of the nuts and bolts had not been put back with them and that was a major maintenance error that caused the airplane to break up due to this malfunction.
Now, the one airplane that we lost due to military action was over Kosovo and that was when we were fighting the Serbs in that was in the mid-90s and that was very, well, there were two stories that I want to relate that refer to the way in which top security sometimes acts against you and at the opening of the first Gulf War General Glossop who was in charge of our Air Force people, and a very competent general knew that we had the stealth fighter but I think didn't know enough technical details about how it should be used. In doing this, on the first day of the war, the war started, as you may remember, at 3am one morning and the F117s were going to go into Baghdad and try to knock out the basic central control stations of the Iraqis. General Glossop sent out this wild weasel group to knock out radars. He sent up a fighter escort for the F117s. He did everything pretty much as had been done before in similar situations where he was sending bombers in to hit high objects or targets. The result was when our guys got over Baghdad all hell had already broken loose because they were aware that something was going on, and so our guys flew through an absolute hail of lead in the sky and we were lucky not to be really hit by accident. It turns out that entire war we did not even get a scratch on any of our airplanes but you have to say that there was some element of luck there because the amount of stuff that was put up in the air over Baghdad was just enormous. The following morning after that first day, Colonial Wrigley went to General Glossop and said "Sir" he said "Please do not help us. We will do a lot better if we just go in by ourselves. We do not need wild weasels to knock out radars. We do not need a fighter escort. We will do fine on our own". And that's, in fact, how the war was conducted after day one.
Now, let's get to Kosovo, the one that we lost, because this gets back to the same kind of situation of the people in charge not knowing the capabilities of the airplanes they've got. Now one of the capabilities or lack of capability of the F117 is it isn't invisible in every direction you look at it and if I was able to bank the airplane in, say, a 2G turn which is 60 degrees and a radar looked at right angles for the flat bottom of the airplane, even with all the coding materials on it the signal it would get would be big enough to detect it fairly easily. So the consequences that, this goes along with what i call the difference between and, you know, a continual developing kind of situation versus one that, an evolutionary one, versus a revolutionary one. Evolutionary, it means you use a rather, an improved airplane or an improved article to do the same kind of thing your predecessor did only better. If you have a revolutionary airplane like the F117 which now is not detectable by radar you now use it in a totally different way. Now there are several ways you can use bombers to attack targets. You can use them like the B52, high altitude, take advantage of your altitude to avoid detection as much as you can, drop your bombs and they, of course, will be as close to the target as they can be given the dispersion that you naturally get from that altitude.
The other extreme is to rain following where you fly so low that radars can't see you because you're masked by the ground effect and this is typical of tornadoes and how those airplanes, the European attack airplanes, will use consistently during the 1970s and 80s. So it turns out that the tornadoes, of course, are active attack fighters and they yank and bank and so on.
The F117 fly at what is the optimum angle for precision bombing which is about, or optimum altitude I should say, which is about 15,000 feet. The reason why nobody else flies at 15,000 feet is because it's also the optimum altitude to be shot down. The sam systems and anti aircraft guns have a great time between 12-15,000 feet. So, consequently nobody in his right mind with a conventional airplane flies in that area. Similarly, when the airplane has dropped its bombs, because you do not want to show a large radar cross-section to the enemy and the cross-section of the airplane is, in fact, only good between plus or minus 25 degrees of elevation looking up or looking down, the pilot who is a fighter pilot has to show great control because the they have to fly out at not more than about not more than a 20 degree bank angle which is like a Boeing 707, not like a yank and bank fighter, so that's tough, because once a fighter, normal fighter, drops its weapons, it wants to get out of there as quickly as possible and it will turn very quickly and that's the worst thing you can do with an F117. In Kosovo, we had, well, we also, I should say, had a philosophy in Iraq never to fly the same flight pattern twice because in retrospect, for whatever reason, you can imagine that the enemy will have some feeling for the direction in which you came and the direction you fly out just by the bomb pattern that's left and so on. So you don't try and fly the same routes on consecutive days and you certainly do your 15,000 feet in small bank angle.
The people in charge of Kosovo were NATO generals, not United States Air Force officers who were familiar with the airplane. They tried to fly the F117 like a tornado, so it intact flew at moderate to low altitudes. It was flying through valleys and it had to engage in large bank angles just to fly the course. They also flew the same course on three successive nights which wasn't very smart, and the final thing is that this wasn't a real war in one very specific respect and that is that Yugoslav citizens, and we were fighting Yugoslavia were free to roam around Italy and, in fact, it was believed, and I'm quite sure it's true, that Yugoslavs were sitting on the edge of the airfield where the F117s were based, calling home on their cell phones and saying "They're just taking off not. You know how fast they go. They're a sub-sonic airplanes, so they should be there in 20 minutes". So, you know, everything was set-up badly for the 117 just because the generals in charge did not know how the airplane should be used and for some reason our people who were there were obviously not senior enough to make their presence felt. So that was why we lost the airplane I'm quite sure, was because we had a large bank angle, the airplane was seen easily, we'd flown the same course on three successive nights, the Yugoslavs knew exactly when we were coming, so everything was done badly.
J.R. Warmkessel: So returning back to one of the concepts, you said that the airplane was stable on all three axises.
Alan Brown: No, no, the same time.
J.R. Warmkessel: Oh. But it was also known as the Wobbly Goblin, right? Is that true?
Alan Brown: It got known as the Wobbly Goblin for a different reason and that was, and this is another interesting aspect that I learned as a program manager and that is for heaven's sake, don't accept help from people who don't know quite what they're talking about. And, in this case, we had a very competent chief aerodynamicist, Dick Cantrell, and the fins on the F117 were really very, very small and I'm an aerodynamicist and it seemed to me like they were on the small size and I just didn't like it and I talked to Dick about it and he said "Well, we've done wind tunnel tests and we think they're OK." So I said "You're the boss. We'll do it'. We fly the airplane and even if you have a computer control if the control surfaces are not strong enough all the computers in the world won't fly the airplane right because the control surfaces just don't have enough meat to do the job and the airplane was, in fact, laterally waving about and it got after the first flight, quickly got called the Wobbly Goblin by the Air Force guys there. So, of course, the obvious thing to do was to increase the size of the fins and we put them up to what was a reasonable size and I said "Dick, why did you, in fact, make these fins so marginal?". He said "I was trying to keep the radar cross-section down for you". I said "Dick, you don't understand how radar cross-sectioning works. It doesn't work just by what you can see from the front like airplane drag." He was trying to hide them behind the rest of the airplane. I said "In fact, if you have the surfaces at the right angle and the leading and trailing edges at the right angle, the radar cross-section goes down as the size of the article goes up because the longer it is, the smaller the spike, the narrower the spike width you get with the radar". So I said "What happened Dick is that you went ahead and did something which you knew wasn't the best thing aerodynamically because you thought you were helping me, but you never checked with us radar guys as to what, how it really works. So please do not help" and I was very adamant about that in future occasions, not just aerodynamics but with everybody, but to make sure that this revolutionary airplane did not get screwed up by well-meaning people who were only trying to help because, you know, that's a very common disease in advanced design of any sort."
Direct link to mp3 audio file of show (right-click to download/save).