Check 6 Revisits: The Sweeping Influence Of The B-47 On Airliner Design
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When you get in the front seat, even with an instructor pilot in the rear, you must have full knowledge of the aircraft. Its systems, emergency procedures, its capabilities and limitations. It can pay off with your life sometime. How fast does a B-47 really go? What's the scoop on altitude? Does the sweatback wing really stall out easier? What's the range? Wait a minute, fellas. To fly the B-47 safely, you must learn it thoroughly. Believe me, you can't learn it overnight.

So absorb all the training you can get. Absorb it thoroughly. Now sit down, fellas. I don't want to scare you. There's nothing mysterious about the B-47. It's a good plane, a safe plane, provided you know what you're doing at all times. Welcome to Check 6 Revisits, where we comb through more than a century of Aviation Week and Space Technology archives. On this podcast, our editors explore pivotal industry moments and achievements of the past while considering how they might relate to the events of today.

I'm your host, Christine Boynton, Aviation Week Senior Editor for Air Transport, and today we're flipping back through our archives to the 1940s.

Big Band was on the radio, Betty Grable was on the big screen, and Aviation Week was reporting the idea of a new swept-wing bomber. It was a decade of radical design for both the weird and wonderful, and commercial jet airliners as we know them today can trace pieces of their familiar shape back to this era. Joining me today to dive into this is Aviation Week defense editor Steve Trimble, Aviation Week senior editor Guy Norris, as well as a special guest armed, of course, with their own archive,

Mike Lombardi, Boeing Senior Corporate Historian. Thanks for being here today, Mike. Great to be here.

So we started out with some audio from a 1952 Army orientation film about the B-47 because that's where we're kicking off today's episode. With the first of the big swept wing bombers and a real milestone in aviation history and design. A September 1947 issue of Aviation Week reports, Boeing's ex-B-47 stratojet bomber heralds a new era in U.S. aircraft design.

By introducing the drag-alleviating swept-back wing for the first time in a combat aircraft in this country, Boeing is pushing the modern tactical airplane into the transonic speed regime and casting the shadow of obsolescence over all previous jet bomber designs.

So on that note, what a lead, right? On that note, I have been dying to hear what you have in your archive on this. Can you take us back to the origins of this program? Yeah. Well, and based on that, what I've always argued is that the B-47 is the second most important airplane in history behind the Wright Flyer. And I know that's a pretty bold statement.

But what you just said, it was a revolution in its time. And it still is vastly important to aviation today. It set the basic pattern, the shape, or the optimal shape for a subsonic jet.

All the jets that we build at Boeing today, at Airbus, they all follow that design. The swept wing, the engines hanging under the wings and pods, and that was discovered on the B-47. So, start with that. A bit of a bold statement. But where it started, and it started with a very famous person. And it, 1939,

And it was Eddie Allen. And Eddie Allen was the world's greatest test pilot. If you are familiar with aviation in the 1930s, every airplane during that period, when it went out to make its first flight, Eddie Allen was the test pilot. He was so well regarded that...

insurance companies wouldn't insure an airplane unless it was signed on there that Eddie Allen was going to fly that airplane. That's how brilliant he was. So he started out with Boeing as an airmail pilot flying for Bill Boeing's Boeing Air Transport. And then he went to Douglas, he went to Consolidated, he went to Lockheed, he flew all these great airplanes and

But in 1939, he came to Boeing to stay. Bill Johnson, the CEO at Boeing, hired him to come to the company. And what Eddie Allen did was just brilliant. He created the modern flight test program. He established a flight test team at Boeing, a flight test department, and a scientific approach to flight testing.

So that was the first thing. The second thing he did, and this is where it fits into this B-47 story because it's fundamental, is that he went to Phil Johnson, the CEO, and he told him, he said, Boeing needs a wind tunnel. Now, no other companies, I think Lockheed had started one, but everybody had to go to the universities to do flight tests or wind tunnel testing. Caltech, University of Washington, MIT, NASA.

And you had to wait in line for sometimes months to get tests, and you couldn't do anything consecutively. So Eddie Allen, he said, we need a tunnel. A million dollars at that time, 1939. It's the Great Depression. Boeing was actually in a bit of financial trouble at the time. And this was what was brilliant, is that Johnson said, you know what, Eddie, you're right. We're going to build that wind tunnel. And another brilliant thing is when they started it, they brought in Theodore von Karman,

the great aerodynamicist from Caltech, and consulted him. And he said, he told Boeing, he said, you need to think about making this tunnel capable of doing tests up to nine-tenths Mach, 0.9 Mach.

And he had in his, the theory is in his mind, he saw that jet engines were on the horizon, that high speed was on the horizon. And this is another great decision is that the team at Boeing agreed. And so we had the first high speed wind tunnel. And because of that, Boeing was able to do all of these incredible tests that led to the B-47.

So I think that's an important thing to remember is that Eddie Allen really is the hero of the story. And the unfortunate thing about this is that once they got the tunnel going, the war started. Eddie Allen was out testing the B-29, the new super bomber, the war winning B-29 super fortress.

And, and famously the, this, or this, this terrible tragedy occurred where the airplane caught fire and crashed and, and we lost Eddie Allen. And again, the world's most brilliant test pilot and the, and the, uh,

scientific test pilot, engineering test pilot, set the pattern for all of our pilots today who are engineers and scientists and no more of the daredevil pilot that they see the right stuff kind of thing that this was what Eddie Allen gave us. And he was just brilliant. So there's a very human side to all of this and we forget that. And one of the things

that really drove this home for me at this human story was when that wind tunnel was started, that Eddie Allen, that he told the Boeing leadership to build. When it opened, the day it opened, they took a picture of the ceremony and it was Eddie Allen's wife

She was given honor of starting up the wind tunnel with George Shire. And in this image, they're all, they're still mourning the loss of Eddie. And you can see the pain in their face while they're in this ceremony. And it just brought it home, the real human story behind all of this. And so, and that's what, that's what's so great about it. There's so many incredible people throughout this story. It would make a wonderful Hollywood movie, but that's the foundation for this.

The next great part of the story, the next person, the next hero in this story is George Shire, Boeing's lead aerodynamicist. He came from consolidated. He brought the technology of the Davis wing, the long, thin airfoil, high wing loading, which was a bit of a heresy at the time. But he brought that to Boeing.

And it went into the B-29, that airfoil on the B-29. And so he was a very well-respected, highly respected aerodynamicist, brilliant, brilliant aerodynamicist. And so, again, this is the wars going on. It's coming towards the end of 1945. Or, I mean, in 1945, the war in Europe is starting to come to an end. And the...

Hap Arnold, head of the United States Army Air Force, was very interested in research and development. He knows that the United States needs to get into Germany and find out about all the research that Germany was working on, aerodynamics, jets, rockets. And so he created a team called the Scientific Advisory Group.

And it had Von Karman headed up the group. Dr. I think it's Sin from Caltech was on the group. And then he invited George Shire and they were given the mission to go to Europe. And all of them were we had been kind of thinking about talking about the swept wing. They were here at Boeing. We were working on a jet bomber, as were other companies across the country and notably North American companies.

with the B-45 was first to have one out, but Boeing continued to work on the idea and Shire understood that there was an issue with the drag increasing as these straight winged airplanes, as they went faster and faster, the amount of drag increased. And so they knew there was something that, there was a problem and how to fix it. And they kind of had an idea about the swept wing, but not,

solid knowledge. It actually was, it turns out they'd forgotten about some knowledge they had prior to the war. So Scheuer goes to, they fly into Paris, they follow the American army, United States army into Germany, and they go to the Hermann Göring Research Lab, this great Luftwaffe research lab at Volk und Rote.

And what's fascinating about this research area is that the Germans had done this incredible job of hiding it. There were no roads, no railroads to it. Everything was underground. It was hidden in a forest. None of the buildings could be taller than the trees. They were all covered over. They're actually stork birds nesting on top of this building. It was so well hidden.

And throughout the war, the Allies never had a clue, never saw it. It was never touched. And as a matter of fact, when the story goes, when Shire and the other members of the scientific committee group got there, some of the scientists didn't even know that war was over and they just they didn't know what to do. So they just kept doing their work. So anyway, they arrived there.

And started interviewing these different German scientists, and in particular, Adolf Bussemann, this great aerodynamicist. And Shire, they started talking about the swept wing or about the problem that Boeing was having with this jet-powered bomber. And Bussemann said, don't you remember back in 1935, we all went to Rome together?

For the Volta Conference, it was this general, Italian general, Arturo Croco, sponsored this. And they talked about the swept wing. And Croco drew this funny little drawing of a swept wing plane. And they're, oh, yeah, of course. So Shire, he wrote this all down.

And he figured out how the mail system worked because, you know, things leaving Europe had to all be censored and looked through by army intelligence. So he figured out how that worked. I think he wrote on the outside of this envelope.

that he was sending back to Boeing. He wrote censored or something on it to get it through. And in that note was all of this information about the swept wing. And he was telling the team back at Boeing, back here in Seattle, he was saying, here, test this. And our brand new wind tunnel, our high-speed wind tunnel, sweep the wing, sweep the airfoil back and see how that works. And so they did, and they found out that was the answer to that problem.

Wow. And Steve, I know you found what was a fascinating paper that Scherer authored, and he goes into a very interesting, what was it, a 26-hour flight with some of the names that we were just talking about?

Right, right. Well, so it was a paper that Scherer published himself in 1980 in AIAA. You can look it up today. It's called Evolution of Modern Air Transport Wings. And it refers specifically to this episode. And that was a fantastic telling of that story. I loved every bit of it. And there was a lot in there that I haven't seen in my own research on it.

But, you know, there was another part of that story, too, that was happening in the U.S. because while Buseman did come to this realization first and then actually published it or presented it in 1935 to an international audience that included Theodore von Karman, nobody really took any notice of it at that time.

And so all the U.S. scientists came back from that and kept working on straight wings. Meanwhile, Buseman starts in a classified setting, starts working on applying swept wings to German aircraft.

Um, which they didn't actually get, you know, they didn't move very far. I mean, it was mainly just experimental research. I mean, there were a couple of German aircraft that use swept wings, but not really for the purpose of drag reduction. That was for the purpose of center of gravity. But, um, meanwhile, there was, uh, Bob Jones, RT Jones at, at NACA who, uh, well, not simultaneously, but several years later, but still independently, cause he's unaware he wasn't at, um,

At Volta, von Karman was there and Jones worked for von Karman, but von Karman never told him anything about it and had forgotten it. And so he independently comes up with, oh, wait, you know, there's this way to increase the critical Mach number of a wing by changing the angle and sweeping it back. And that can solve our problem. Meanwhile, Boeing had been responding to an Army Air Corps call

RFI. I mean, it was probably called something else back then, but it was basically in 1943 saying, hey, jets are coming along. We'd like to figure out how to put on a bomber or maybe a transport with long range. We're going to do on fighters. That's a little bit easier. But if you guys have any ideas how to do that, we'd love to know because it's, you know, this straight wing problem, this critical critical Mach number problem. We can't figure out how to solve it.

So George Scherer is already thinking about this. And on the flight over, this 26-hour flight in a Douglas C-54, a DC-4, he is talking it over with Xianxusheng, the Japanese personal laboratory that later founded China's aeronautics and aerospace industry.

Big hero for Chinese rockets, yeah. Right. He's the grandfather of Chinese aviation. But at the time, he was in the United States working for von Karman and on this intelligence expedition with these other aerodynamicists led by von Karman to Germany. And on this 26-hour journey, Su Shen had been – or Cien, I should say – had been –

I read into Bob Jones's work and sure, I'd heard about it, but they discuss it on this 26 hour flight. Can you imagine 26 hours from Washington to Paris? And on the way, Scherer writes that he he determines that based on this, based on his discussions, that this will solve the problem.

Um, and that, uh, you know, so getting the, the wind tunnel data, uh, at Vulcan road, uh, from the Germans was, was just this bonus. I mean, he had just figured out how to solve this problem for the B 47. And then here's all the research data, you know, years where the research, uh, wind tunnel data that he can immediately apply on, on his own airplane. Um, and, but the funny part, uh, just the, the, uh, the little anecdote was after they land in Paris, uh,

Von Karman, after this 26-hour flight, walks up to Scherer and says, now I understand why you want to fly fast. But it wasn't... The interesting thing is that I found was that... So they come up with this discovery, but then...

They still have to figure things out because this is a new technology. And as they apply it on the B-47, they find new problems that they weren't expecting, one of which turns out to be high mock pitch up.

which was something that really surprised them because up to that point with straight wings, they'd only seen a high Mach pitch down or Mach tuck, which is a problem that P-38s and other straight wing aircraft had with compressibility. For some reason, it was pitching up a swept wing aircraft like the B-47. And Scherer writes in that paper that they solved that with vortex generators.

And, you know, he doesn't say why or how that solved it, but I can sort of imagine. And I'm going to try to put on and I'm not an aerodynamicist or a mathematician of any kind. If any aerodynamic experts want to write letters, please, I would welcome your feedback. Please send them to me. I'm at G-U-Y dot N-O-R-R-I-S. That's great.

Well, so they solved that problem, but they did that, I think, by using those vortex generators to re-energize the airflow so that the control surfaces would be more effective to counter the pitch up. They also discovered, according to Scherer, that the critical Mach number increase they were getting was only two-thirds of what Buseman's theory would have predicted. And that puzzled them for a while. And

they actually made an important discovery that would have a major effect on transport design as they moved from the bicycle landing gear configuration of B-47 to tricycle landing gear, which is that if you increase the thickness of the wing route, where the wing meets the fuselage,

That solves that problem. They were able to increase the critical Mach number much higher or slightly higher to get closer to what Buseman's theory had predicted for the B-47.

They also experienced some new rolling moments in yawed flight that they had to counteract by increasing the size of the ailerons and flapperons. They needed to really figure out the yaw dampers to counter the Dutch roll for a similar problem. And then they also had to figure out how to beef up the fuel systems because of this low dihedral with a high swept configuration

It meant that the kinds of fuel systems and vents that they were using for straight wing designs were inadequate. And, you know, so they had to figure that out as well. So, you know, they came up with that solution, but then they would create a whole bunch of more problems that they just aerated so quickly through. That's one of the more impressive things that they got through all those so quickly.

Yeah, and it is. And that's why I think it's it's this is such an inspirational story because that any one of those things they could have just thrown their hands up. Right. And said, boy, we don't know what to do. But they kept pushing through and it was always some simple thing. It's a well, just go over the shop and get a get this little piece and this little, you know, like you mentioned, the the Dutch roll.

You know, that was Bob Robbins, the test pilot. Some of the team that was watching on the ground, they could see the plane kind of doing these S turns through the sky. And they're like, hey, Bob, did you notice the plane? No, I didn't really. And then they paid attention. It was like, yeah, there's this roll. And so they just built a yaw damper. They called it Little Herbie, Little Herbert.

And, you know, and then even in that, it was like, well, how much deflection? And, you know, what? Well, how about five degrees? Let's go with that. And should there be feedback for the pilot? You know, just these decisions, these real important decisions. They're like, you know, let's just go ahead and no feedback. And they perfected it right there. And that's something, you know, they found an inherent problem in the swept wing jet with the Dutch roll.

And they fixed it. And then it was no problem. I think even some of the, it was Douglas had a turboprop they were trying to pitch and they were going to use that against Boeing and said, well, look, their jets are unstable. And the Air Force was like, no, no, no, Boeing's got it fixed. It's not a problem. And so it's just brilliant. All these moments that could have just ended this and they just pushed through with just

Just using their instincts and their inherent knowledge and just believing in themselves. And it's just that's what amazes me. Again, it's just a great people story. Right. Guy, I think there's a great story in here, too, about a secret screening in Kansas that has to do with overcoming some of these challenges. Is that right?

Yeah, well, just before I do go into some of the quirky parts of the flight test story, which was predominantly in Wichita as well, we have to, even though the airplanes were built originally in Seattle, most of them anyway, Mike mentions this is a human story. It's very much so. And when I think about, you know, like Shira, for example, was only 26 when he joined Boeing in 1939, coming out of

consolidate and of course you know he'd been to Caltech because consolidated had sent him up there and that's where he got his great sort of uh wind tunnel experience I think to start with and you mentioned Mike had mentioned Eddie Allen and the tragic loss of him you know that um that uh terrible crash in 1943 but the weird thing was that as a result of that and Mike probably correct me if I'm wrong here but there's a fallout of that the whole

engineering and aerodynamics had to be restructured slightly. Because of that, Shira was

was uh sort of directed through the ranks really and rose up so by the time that boeing had brought on you know theodore von karmann and and john markham these mit brilliant people from this best theoretical aerodynamicist from mit to help consult on that wind tunnel the advanced high-speed wind tunnel that mike mentioned you know uh shira was on his way up and um and ed wells who who you

you know was a key figure at that time just appointed chief engineer um he was the one that said said when hap arnold's team came to him to say who should we send he was the guy apparently mike right who said you know we need to send spira he he'll go and um chiro had already said you know we need to go fast everybody knew that but what here's another weird thing so um

When this group was getting together to, you know, who should go to Germany and that sort of thing, two of the fellows that Shira remembered said,

was Bill Sears, who, and everybody who knows aerodynamicists history would know that he was one of the two people, Sears and Hack, who put together the Sears-Hack body, the classic lowest theoretical wave drag in supersonic flow. It's the shape that anybody who's a student of that will learn about today, you know. So it was that Sears. And he was also, by the way, lead developer of Jack Northrop's flying wing programs over

Oh, by the way. So him and Xi'an Shusheng, who Steve had mentioned as well, who, by the way, we put on our front cover in 2008 as the person of the year, as the father of Chinese rocketry, the space program.

They went to Princeton and they were in the run up to this and they of course bumped into Bob Jones of, you know, the, who really, you know, Shira does actually credit at the end of the day with the reason that they really were looking at all this. And

What I didn't realize was that Bob Jones was basically, and according to Shira, you know, a self-taught, a poor boy, he calls him. He grew up as an elevator operator in the Library of Congress. Actually, he turned out to be an operator in the House Office Building in Washington, D.C., but he spent his spare time studying in the Library of Congress, where he met this guy called Albert Zam, who was chief of the Aeronautical Division of the Library. And

And because of all these amazing people he met and he, you know, Bob had been a left college or something to go to a flying circus. I mean, the guy was obviously crazy about flying.

So he'd read all in the elevator while he was waiting to operate the lift. He read mathematics books. And because he met all of these experts who came in and out of the elevator, they all advised him on what he should read next. So through all of this process, he's sitting there in the elevator. He invented the idea of the thin wing theory. I just love all of the fact that you've got all of these amazing,

amazing characters who are household names to anybody who's at a science, you know, aerodynamics conference. And they were all like bumping into each other almost in a haphazard way. So,

Anyway, so as Steve mentioned, you know, they went on this torturous 26-hour flight to Paris. And the bit that I remember hearing about from Shire was that he said that Carmen was a great pacer. He would always be pacing up and down. So when they finally got to Orly after flying via, I think he said, Gander and Keflavik and the Azores and 26-hour Odyssey, they looked down into the apron. There he was pacing up and down. And that was the bit of,

story about you know he always wants to go faster so um anyway so moving forward then um

Getting to flight test, the great things I think about the story are the fact that because swept wings were so new, they thought, well, hang on a minute, you've got a thing which has actually got a smaller span. It's got more weight because it's a dry wing. In this case, you have to structurally compensate for that. And because it's a dry wing, you don't have enough fuel either. So how on earth are you going to meet the mission? But

But of course, as you pointed out, Mike, they began to find out there was actually more advantages than they thought. They, you know, had a high wing loading of over, I think, 105 pounds per square foot. But they kind of kept coming into these unexpected discoveries like washout at the tips, you know, improved cruiser efficiency. And hey, presto, you get bending moment relief because you've got jets underslung outside on the wing.

So, oh, no, I was going to I would just say that that was another one of these that, you know, and maybe even in a little bit we can talk about Ed Wells and the engines. But that was one of the one of these moments where they were trying to figure out where to place the engines. And they did. They called it the broomstick test.

where they put a little model of a nacelle. They called it the potted engine. And they placed it in different positions around the airfoil in the wind tunnel. And they found the optimal position was below and forward. And so that's why, and that's the way it is today, right? And that,

And that at the same time, it solved a turning moment that they had with the wing. And lo and behold, there it was. It solved another problem they didn't even foresee. It's just brilliant. And one more, one more, and I'm sorry to interrupt you, Guy, but this is so many great stories. The other one is the question about what degree of sweepback

And, and again, it was one of these moments there, there's, they're in the, they're, they're in the wind tunnel trying to decide about, you know, how to make this model of the wing, what degree. And this, one of the aerodynamicists at Boeing, Vic Ganser, he stepped up and he said, 35 degrees, let's go with 35.

And it was brilliant because after they did, they refined the test, they settled at 37 as the optimal position. So, and Gansler, he went on to be a professor at the University of Washington and trained generations of Boeing engineers. It was just brilliant. And it's just these, all of a sudden, just these guesses, I mean, you'll pull your, you know, just...

Your calculator out of your pocket, your slide rule and do a quick, oh yeah, this is it. It's just incredible. They were so brilliant and so confident in their abilities. And it's just what an inspirational experience.

this was. And fast as well. I mean, they went from deciding to do this to flying it in about two years. You know, when it flew in December 1947, that was literally two years since they decided to

to come to get the thing built. But I mean, and just a couple of things on what you were saying, you know, like, and Steve had mentioned the, you know, the wingtip unloading that, you know, so many lessons learned that they had no idea about, you know, leading to that sudden instability. And, and of course they realized, well, the tips of the wings, because they're swept, they're halfway back towards the tail. Yeah.

So it's like, wait a minute. Well, that's probably why they're beginning to act like elevators in a sense. And so, of course, then they realized that they could compensate by the changing the stabilizer angle. And then they had this curious bit of body bending. So they were beginning to figure out, wait a minute, this is aeroelasticity, you know, in a transonic aircraft. It's like, whoa, what's going on? And then...

Aaliyah on reversal, you know, of course, the creation of spoilers or development of spoilers to help cure that.

um and i i don't think ken holtby you know you know that name as as well because he was he was the air force officer who was uh contract the contracting officer for the xb-47 and he said um he said we had this great floppy flexible airplane and we didn't understand it you know so it's and then the dutch role that you mentioned that and little herbert um

I loved the story that Bill Cook, who was the ex-B-47 aerodynamics unit chief, said. He said, you know, we basically just said, well, we've got to do something. And they brought together all these bits. They had a turbo wastegate control from a B-29. They found a transformer and a servo motor from somewhere else. And then they kludged it together with a Honeywell gyro. And hey, presto, we had this sort of Heath Robinson creation, which is,

today still is in every Boeing, not in obviously a modern version of it, but it's still a yaw damper and it's still flying today. And then my final bit, little Herbie, the flow separation. So this is the bit to answer Christine's question about where Wichita comes in.

The flow separation, which they didn't really expect, and Steve mentioned this before, was this outboard section where the airflow was separating during maneuvering and transonic accelerations and causing this sudden pitch up.

And of course this magic formula of vortex generators. Now NASA had previously, or NACA, I guess in those days, had tested them, but on a straight wing. So again, you know, the theory was there, but nobody had really looked at this in a swept wing. So to figure out what was going on, they toughed it, you know, to completely, today it's an accepted way of visualizing the flow, but how do you record what's going on? And so they, what they,

put a 35 millimeter camera on the top of the fin, which was also swept again, another innovation. Um, and to look, to focus on the tufting that they could see from the camera. So this was great. Except when they got back to Wichita, they realized that nobody had a 35 millimeter projector. So, so they were okay. So they went out, went downtown Wichita, rented out a local cinema, a movie house. And, um,

Because it was still classified, I think test pilot Dick Taylor, who was one of the test pilots, remember this? He said, we had to darken the house, seal all the doors. And then, of course, the projectionist couldn't be read into the program. So the projectionist had to operate the machine, but he wasn't allowed to look at the screen. So

They had to sort of say, you know, he had to operate the lens to get it in focus and they would say left a bit, right a bit. That's good. But he wasn't allowed to look at what was going in the screen. Anyways, good stuff. Yeah. It's just, uh, yeah, it was, it was just brilliant. Uh, so many things that, that they discovered and, and, uh, and again, they just faced these issues and it took them head on and with just this incredible confidence. Yeah.

There was one other thing I thought was worth mentioning. And obviously the German, you know, as Steve mentioned, you know, the data and the fact that the Germans had done a lot of the basics and were kind of backed up what they already were beginning to suspect. But there was some other discrete elements of German technology that, and I think even Dick Taylor might have mentioned this,

The weird thing about the B-47 was the engines were so primitive. Like all of these early turbojets, they took a long time to spool up and spool down. 30 seconds in the case of these original GE engines. And they had to... So that means when they're coming in on approach, they came in real hot. So they would be coming in over the fence at about 140 knots, touchdown at 136.

Because they had to keep the engines really spooled high. And of course, they didn't have reverse thrust. They didn't have anti-skid brakes. None of that had been invented. Not yet. Not yet. They were working on it. Yeah. Yeah, right. And so...

Dick Teller had said that they'd been flying B-17s down to Antarctica, I think, for the first time. And they were worried that things wouldn't be able to stop on the ice. So what they'd come up with was an idea of throwing parachutes out of the waste gunner positions. And they said, well, why can't we do something like that?

So they did get, there was a guy from Operation Paperclip, which was the great, you know, the Allied plan to get as many of these people as, like von Braun, for example, was a Paperclip guy. These scientists and engineers. And he was working, I think, at Wright Field by then. And he'd invented this ribbon chute, which had been developed for the Arado AR-234 Blitz Bomber.

And that was what they ended up using. Isn't that brilliant? Yeah, that was. And actually, I think Dick Kaler and Hill, they talked about flying the B-47, how the airplane would just continuously just glide over the runway because it had the high lift devices when it was coming in. So it's got good lift and with the bicycle landing gear.

they had to maintain pretty much the same attitude that the airplane would have when it was taxiing. So that was not just because it was hot, but it was also just it didn't want to land. It wanted to stay in the air. So, yeah, well, that was brilliant. Yeah. Hence the training video that Christine introduced us with. It was pretty a kind of handful, basically, you might say.

That was one thing about the airplane is that as flying the airplane, you had to constantly fly the airplane. When it got up to altitude and speed, the high-speed stall and the low-speed stall were

were just a few knots from each other. So you constantly had to fly the airplane. And so it, but it, you know, it was such a pioneer in so many ways. And what they learned, not just in developing the airplane, but as you're saying with pilots like Dick Taylor and Brian Weigel and what they learned flying the airplane and passed on, it's just brilliant. Yeah. And of course,

all these technologies then laid the groundwork for the 707 and really what we know, great commercial jet airliners of today. Right, right. Yeah, and that was, you know, and the one other piece of this, and if you don't mind, I wanted to talk about Ed Wells and his brilliant contribution because there's two parts of this brilliant discovery. There's the swept wing, but there's also the position of the engines.

And this was a really great story, too. One of the things that Boeing understood very well was...

was engine, during the war, all right, so our bombers, B-17s, B-29s, they knew that what caused most of those airplanes, the loss of those airplanes was when they took damage to the engines. So enemy fire would hit an engine, cause a fire, the fire would spread to the wing, get to the fuel, and that's how most of our bombers were lost in combat.

So one of the things they wanted to do with this new bomber was get the engines out of the wing. And that was the conventional thinking. You look at all of the jets, these first jets that were developed, whether it's the B-45 or what Consolidated was doing, what Martin did in competition, they all had the engines in the wing. That was the conventional thinking.

And Boeing wanted to get away from that. And they puzzled over this. And even they made a design where they pack the engines onto the fuselage. So they had four jet engines right behind the pilot on top of the fuselage.

And they took that to the, back to right field. Yeah. And they took that back to right field. And, you know, it was Pete Warden, Colonel Pete Warden was evaluating this. And they said, no, there's just no way. And they showed them, they had done a test on a P-80 where they shot the engine while it was running. And here's this, I guess they said something like 18 foot long blower.

blowtorch and they said, we don't want this on the fuselage. That's not a good idea. So plus,

it made a really ugly airplane. It was hideous. And we all know that ugly airplanes don't go anywhere. So Ed Wells was back there at Rayfield and on his way home, he puzzled over this. And this is another point I want to make towards the end too, just about engineers and some of my thoughts about educating engineers. But anyway, Ed Wells was a brilliant artist.

He was a painter, did beautiful paintings. And so on his way back, he puzzled over this whole problem. And he made these drawings where he put the engines in, he had them in pods and he hung them off the wing. And this is where that idea of hanging, the podded engine idea, hanging them off of wings, nacelles suspended off the wings held by struts.

And that's, I mentioned earlier, they got back to the wind tunnel in Seattle. Again, Boeing had this wonderful facility to do all these tests. And they did that broomstick test and determined that was the best placement for the engine. So they invented this brilliant invention of hanging the engines off the wings. And so that was it.

Sorry, Mike, do you have those drawings in the archive? Yeah. Yeah. Right. Yeah. So it's just brilliant. And that was the part. And you speak about how brilliant Ed Wells was. I mean, George Shire. But Ed Wells, just a man. He, of course, we still honor him as our greatest engineer here at Boeing. And he continues to inspire our engineers. But yeah.

It was just brilliant what he did in thinking up this idea, amongst other things that he did. So those combinations together, that was what was brilliant is that they brought these two big items together. And again, it's because of the brilliance of a particular person, these wonderful people stories.

Yeah, and they made that combination, made the B-47 this beautiful jet. And I think it is one of the most beautiful jets ever. It's just, yeah, right? I mean, that's just, even if I didn't work for Boeing, I would think that it is just a beautiful airplane.

And you're right about the human aspect. I remember Phil Condit even saying that Ed Wells had advised him on some aspects of when they were doing the 7.5 and 7.6 and saying, you know, we made the big mistake of making the 7.07 gear too short. So when Douglas stretched the DCA, we couldn't do it. So he said, never do that. Make sure the 7.5's got some big tall gear. And he said, that's why it looks the way it does today. Yeah.

Absolutely. And that's a great point is that, you know, Ed Wells, he started, what, 24 years old. He was the assistant chief engineer developing the B-17. 24 years old. And then he was here through the 767. He was on the board of directors.

So, you know, that's those, it's just, um, the, the, the type that the people that did this and it, I think it would make a brilliant movie. It would be a wonderful movie. Yeah. Who's going to, who's going to play Shira? Oh, right. But yeah, that's, um, and so one, you know, and one final point to make about this, uh,

about the B-47. And I know you want to go on and talk about some other things, but this was such, you know, the Air Force called it a revolution. And for Boeing, we looked at the Boeing, our marketing team, our communications team looked at what was going on and they said, you know, this is, we're moving into a new area. We're moving into the future. We need to change. We need a new trademark, a new logo for Boeing.

And so they created the stratotype. So our Boeing name is at an angle. That angle is 37 degrees because of the B-47. And that is our official, that's an official brand, right? That's just not me saying that, well, that is our brand, is that the angle of our stratotype

that we use for the Boeing logo and other Boeing official names is 37 degrees because of the B-47 wingsweep.

Well, I do want to get into more of the designs of the time to bring it back to the 40s, more of the weird and wonderful. But before we get to that, I just want to come back, Mike, to you to ask about some of the weird and wonderful you may have found in your exploration of the archives before this podcast. What did you uncover? Well, I think one of the things I want to share is that...

some of the things we talked about here. One is the Shires letter that he sent back that started all this research is still in existence. And it actually ended up at the Museum of Flight where they keep it in a safe there. But we talked about, I talked about Ed Wells drawings, which we have here. And one of the more interesting collections we have is that all of this research that was done in Germany, all these, the research that the United States,

brought back from Germany, all the documentation, a lot of it was microfilmed. We have that. We have the entire set of these documents. A lot of them have been translated, the microfilm, through the various mergers that we've had with Douglas and North American. North American gathered up a lot of this and it was used for the F-86 as well as a little bit of Shire's letter. But we inherited that. So all that information is part of our archives.

along with the memories of these brilliant aerodynamicists and engineers and leaders who did this, we have this tremendous archive with all of those records. So it really is. And the photography of all these wind tunnel tests and those actual tests that we talked about back in 1945, 46, we have all those records here. They're preserved in our archives. So it's an incredible treasure.

That's amazing. And so what else was being explored around this time? And Steve, I think I'm going to toss it to you. I know we had a lot from Jack Northrup, right, around this time. And we kind of touched on that earlier.

Yeah, yeah. And Jack Northrup. Yeah, he's another great story, too. We could go into, you know, a guy was talking about Bob Jones's story. I had no idea that he was elevator attendant to learn aerodynamics at the Library of Congress. That's incredible. But I mean, Jack Northrup is another just amazing character. I mean, he never went to college. He graduated high school in Santa Barbara, eventually started working for Lockheed and went to Douglas.

But he had this idea, this vision for flying wing aircraft. As far back as the early 1930s, he started working on a series of his own designs of flying wings, starting with the N-1 and the N-9M. And sort of in the middle of the war, as he's doing other things like the P-61 and sub-assembly manufacturing, he keeps working on this and gets the Army Air Corps interested.

And, you know, with the idea of flying wings. So, and, you know, whether straight or swept, the idea was that you can just get a lot more aerodynamic efficiency if you don't have this big fuselage just along for the ride, that the payload and the crew compartment is all enclosed within the wing.

And, you know, at the time, the structural, I mean, the aerodynamic efficiency advantages were there, but the control mechanisms for the aircraft were not sufficient quite yet, especially to handle the adverse yaw that a configuration like that creates without a vertical stabilizer. Yeah.

And that would later be addressed through fly-by-wire and other types of techniques, control service techniques by the Air Force.

For a while, Northrop tried to get airlines interested in the idea, but there were some passenger comfort issues in addition to just the safety issues that had never been fully addressed, or at least it wouldn't be for a while. Of course, that would come back later on as the Air Force not only saw the aerodynamic efficiency advantages for a non-human payload especially, but also

but also a stealth advantage because you don't have those vertical tails and 90 degree points in the design quite as much as you would with a standard tube and wing. But then there were, I mean, there were, you know, all through, you know, the history of, you know, the industry and the technology, there's been attempts to try to figure out how to do this better, how to make things more efficient,

and not always making the engines more efficient, which is usually the sort of the default, you know, just kind of cleaning up the aerodynamics as best as possible and then trying to do some huge generational improvement with propulsion technology.

But not too many of those have worked out too well. I mean, you think about like the Avro Canada WZ-9, you know, essentially a flying saucer that they attempted in the 1950s with U.S. Air Force funding. That didn't work out so well. Bob Jones, who, you know, we heard about in his involvement with NACA and the invention of swept wing technology. He came back into the picture with...

this idea for the oblique flying wing, which was to kind of come up with a wing that, it was kind of like a straight wing at low speed at takeoff landing and other low speed configurations. But then as,

to address these critical Mach number concerns or issues you have with higher, higher speed flight and high Mach number flight. You, his idea was to simply rotate the wing, you know, 37 degrees, 45 degrees, whatever the right number would be for that airfoil. And they tested it through a NASA and DARPA program and,

You know, but I mean, there are some issues there, especially if you want to scale it up, especially if you have engines embedded on the wing. They've got to translate as the wing changes angle as well. That creates some issues. So there was never a transition path for that.

And then along the way, another, I guess you might call it legacy Boeing project started out at McDonald or McDonald Douglas by Robert Liebeck came up with this idea with the blended wing body.

So you have not quite a flying wing where there is a distinct fuselage, but it's blended into the wing in a much smoother way than you see with a tube and wing configuration, which incorporates some level of blending as well in all modern aircraft. You see that. But that was the idea. Boeing and NASA tested that out with the X-48 aircraft.

Uh, that again brings you a much higher, uh, aerodynamic efficiency. So like the triple seven is sort of the gold standard in a tuba wing design, you know, with a, I think it was a 19 liftover drag, um, uh, you know, uh, uh, Mike Lombardi can, uh, correct me on that, but then, um,

You know, what what Bob Lieback was saying was that we can get to lift over drag ratios of 26, even higher, perhaps by going to this. The downside is it's a lot harder to to build. You know, it's not it's not a circular constant section. It's there's very little constant constant section in the aircraft.

That's just a harder thing to build. It's harder to pressurize, you know, because pressurization like smooth circular type of vessels, not things with 90 degree angles. So then you have to create 90, these circular vessels within it, which reduces a little bit of the structural efficiency that you're gaining from the hybrid, from the blended wing.

And, and then there's a passenger comfort, egress issues and all that kind of stuff. But, you know, and that has been talked about and talked about, you know, but we're still at this point where we're trying to figure out what that next leap in aerodynamic efficiency technology will be. You know, really since the sweat wing, there really hasn't been

you know, anything huge at high speeds. So, and we can't just keep relying on the propulsion to kind of bail us out, perhaps. So, so there are some new projects and I think Guy's got some more to say about those things.

Yeah, thanks, Steve. And just to make the last point is just to build on what you just said about Bob Liebeck and his blended wing idea was that, you know, there are companies, there's a lot of them actually now all trying to push the blended wing body concept like Jet Zero, for example.

with a different twist in each case. You know, Boeing and NASA, of course, work together on the ways of getting around the pressure vessel with the Perseus stitch composite structure idea. So it's amazing what innovation is coming out because of that. Perseus, Perseus, protruded rod efficient stitch unitized structure. See, that's why we love Steve on these. I can never, is it Perseus or Perseus? Anyway. Yeah.

Never mind. So, yeah, and as you quite rightly mentioned, you know, we've been through the move to supercritical, you know, aft-loaded designs, you know, like the 777, of course, as you mentioned, a kind of a gold standard. Improved them in some cases with winglets, you know, like the 737 family, of course, famously did that.

And then recently, well, I'm sort of saying in the last 20 years, I guess we've seen, you know, the introduction of composites, which are stiffer, of course, and structurally stiffer. And that enables these much higher aspect ratio designs, which is really the ultimate way of kind of developing long range cruise efficiency.

And, you know, one of perhaps the ultimate expression of this will be the extended wing tips of the 777X because that really maximizes that benefit and, of course, going to the composite wing for that derivative. But what do you do beyond that? And so this is where it gets really interesting. The latest is, you know, of course, Boeing is working with NASA on the Sustainable Flight Demonstrator, which in 2023 was christened the X-66.

And, you know, this is part of everybody's efforts to try and get to net zero carbon for a next generation single aisle at some point. And so this is called the transonic truss braced wing, TTBW. Not easy to say, which is why a lot of people love the fact it's now called the X-66. Yeah.

But anyway, they're basically looking at this. They're going to do a test program where they're converting at the moment an MD-90. And what you basically have is this high-mounted, slender wing, structurally braced by trusses. And the idea is that it'll be in-flight test by the end of the decade. And most of the design helps in reducing drag because the high aspect ratio reduces the induced drag.

while the low thickness that you get decreases the wave and form drag another good thing about it is you can also get a much shorter cord so that gives you much more opportunity for increasing laminar flow which is like this sort of golden the goal that everybody's driving for that's the great the last great frontier of untapped efficiency in all of these designs how to get more laminar flow now the problem is that if you unsweep the wing it's

goes back in a way back on itself back to the old days of having unswept wings that increases obviously the cord when cord wise length of available lamina flow due to the high transition Reynolds numbers and that sort of thing

And the friction drag has decreased as well. But on the other hand, unsweeping has an adverse influence on the wave drag. So what you've got to do is really balance these two factors. So if you can get a final sweep that balances between these two trends, hey, Presto, you might have it. And that's what Boeing's really looking at with this because they've decided they can do a transonic truss-braced wing with sweep instead

And that's the great big experiment here. So generally adding truss members, you know, reduces the drag panel, drag actually weirdly, and increasing, increases the lift to drag ratio and therefore decreases fuel weight. So you have this virtuous cycle, but it's, it's still as many unknowns. And I think that we're really what we're looking at here with TTBW, X66,

is kind of like getting to the nearest equivalent we've seen really to the Great Leap that was made with the B-47. And, you know, even NASA have said that this could be the Dash 80...

moment again for Boeing because in the future you know the B-47 ultimately evolved as Mike had said towards you know what became the Dash 80 demonstrator and that was a pivotal moment again in Boeing's history and in fact in the world's the history of world air transport so

you know, I don't know. It's the newest wrinkle, but it's the only thing that's happening apart from the rebirth of blended wings in a serious way in subsonic transports.

And from a historical perspective, Mike, when Guy's talking about maybe the next great leap like we saw with the B-47, I mean, how should we be thinking? Are there any lessons that you can kind of identify from the archive, from these past moments that should be on the top of mind as these technologies progress? And I think earlier you said you wanted to mention something about engineers.

Well, and I, you know, and I was, I was going to say from a historical point of view, I, you know, that I always think of the Belanca air cruiser. Just in my personal opinion, I think it should be the X-66 air cruiser. But yeah, it's serious, but you know, a little more serious on that. It really going back to the foundation of, of the Boeing company and Bill Boeing and

that there's a DNA that he put in, a corporate DNA in our culture that he said that his famous statement about never letting, always that we're pioneers, always be looking for the latest innovations, latest discoveries and get those onto our airplanes as soon as possible. That pioneering spirit

So there's a pioneering spirit. There's also a spirit of, like, a can-do spirit that goes together with that, that has been foundational. And I'd say across the aerospace industry, that's just something that's part of being an engineer, that you have that. And I always think about, you know, the space program, the going to the moon, and that effort that's...

We started out with nothing, right? We started out with what Jupiter boosters that were exploding on the launch pads that and then all of a sudden we're planning to build this giant Saturn booster that's going to go to the moon and did that in just less than 10 years. And it's just amazing. But and as Kennedy said, we we do these things because they're hard.

We choose to do these things because they're the difficult things. And that Boeing, I was thinking with people like Wells and Shire, Jack Steiner, Joe Sutter, these famous people that design these airplanes, they understood that. They understood that if you wanted to motivate engineers, you give them, Steiner said this about the 727, if you want to motivate your engineering team, give them something they think is impossible and they're going to jump into it.

And so that's, I think, the important lesson. And going forward, that is going to be a constant. And one of the things that go, and as far as educating engineers, one of the things, a big, one of my soapbox issues is that we've, for a couple of decades now, we've really enforced this idea of STEM education, really focusing on science, technology, engineering, math.

But when I look back at these engineers from these early days, and I knew them, and I talked to them, and when I talked to Joe Sutter, for example, and he would say when they were developing the 737 and trying to figure out where to put the engines, he said, it just looked right to put the engines under the wing. The airplane looked right. And I hear that from a lot of these. Sadly, now they're gone, but they would always say something like,

my gut feeling, or I looked at it and it was, this is the, they didn't say, well, I went back and I used my computer tools or did some calculations. They trusted their instincts. And what the difference was, and I mentioned this with Ed Wells, they had a classical education where they learned, they were taught art, they were taught literature. They, and so in other words, they use both sides of their brain.

And right now we are focusing on just half of your brain and you need that creative side of it to be a great engineer.

And that's why I say that in good engineering, there's actually art. There's beauty. You look at, you know, like for me, I look at the Mustang, the P-51 and, you know, the conical shapes and all that, that they use the combination of math and art. And so this is, I think, is an important mess. Oh, a guy's going to show me. He's got his, oh, and yes, I can't forget the Spitfire. I'm sorry. I had the greatest airplane ever. I

I know, golly, I've learned that lesson too. Don't ever mention the Mustang without mentioning the Spitfire. So these are just beautiful, beautiful airplanes. And the art, it is the art in engineering. And so we need to remember that. So going forward, encouraging that can-do spirit, that pioneering spirit, but also encouraging, educate that engineers, encourage them to learn.

We need to do both sides of our brain. We need to have that spatial part of it where we can see problems and work them out in a spatial format as well as a linear format. And that's what these engineers had. And that's why on the B-47, they were able to, they've come across a problem and say, oh, let's do this. And they were right.

Um, it's just, it was just amazing. All the steps, every step where they, again, like I said, they could have just ended the program, thrown up their hands. Maybe that was some, that maybe that's how it would be approached today, but they were able to push through. And I think that's one of the reasons, one of the big reasons is that they, uh, they were just brilliant and they were able to, they were trained to, to use their entire brain and, and solve these problems.

Wow. That's amazing. Both sides of the brain. I love that. As an English major, I love that. And as a history major, yeah. Right. Right. Yeah. Yeah. So. I guess for the final, as we're kind of wrapping this up, I know we could talk for another two hours, then I would love to. Yeah.

But for our final question, I guess I kind of want to get your perspective on this and I'll start. Steve, you might have the shortest answer. So I'm going to start with you. Are either truss braced wings or blended wing body likely to replace familiar tube and wing within our lifetime? We live in a world that the B-47 created for high subsonic transport and bombers. Right.

And we just haven't found a way to beat that from a from an overall perspective, which includes how you integrate it into an airport, how you refuel it, how you maintain it. Those are all important considerations.

But part of that has been driven by the fact that propulsion, advances in propulsion have always bailed us out on this drive to increasing efficiency more and more. And the question is, can we get more, can we squeeze more out of that propulsion side than we already have? There are efforts afoot with hydrogen power, which we've covered just in a most recent podcast that are not progressing that quickly.

So that's a long answer, longer than you were expecting. But it's going to be hard to beat Tube and Wing. They're trying to do it, but they're going up against a mountain of a challenge when they do it. Guy, what do you think?

Yeah, there's no argument or anything Steve said there. I would just add that what we are now looking at is maybe a diversification, a period where we've never had the opportunity really to expand beyond tube and wing in a realistic way. And I think now, thanks to several innovations,

and the coming innovations in things like distributed propulsion, maturity and different structural capabilities and design techniques. I think there will be an opportunity at different scales for new shapes in the sky. So for the big long haul, you know, the classic, the 777, A350, 787, I think those are going to stay. I think it's going to be difficult to replace that.

But in the smaller markets, you know, and in maybe the 737, A320 area, there is an opportunity for new innovations and things like TTBW, kind of those shapes.

And as you get even further down the scale, you know, some other things too. I mean, look at the advent of eVTOLs, for example, maybe. But the point is there are niches developing. And I think within that, even blended winged bodies have an opportunity in that mix. So I wouldn't discount it. I think that within, hopefully within our lifetimes, we're going to see some big changes and new shapes in the sky.

Awesome. Excellent. Well, thank you all. And on that note, I think we'll wrap this episode of Check 6 Revisits. A very special thank you to Mike for joining us for this today. And thanks also to our podcast producer, Corey Hitt, and to Steve and Guy. For Linkstar Archive, check the show notes on aviationweek.com, Apple Podcasts, Spotify, or wherever you get your podcasts. And

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