North American XB-70 Valkyrie - Feature from the National Museum of the USAF

[Music] hi welcome to the national museum of the united states air force i'm dr doug lantry from the museum's research division and we're standing here beneath the massive and legendary xb70 valkyrie the purpose of the xb70 program was to enhance nuclear deterrence it was meant to be a high-speed high-altitude nuclear bomb delivering aircraft and that was its role in the early part of the cold war it was an early part of the so-called triad bombers submarines land-based ballistic missiles let's talk about the canards on the xb70 they're a really unique design feature and this airplane has unique geometry the canards contribute to that geometry by solving a really important problem they're a trim device that solves stability problems between the low speed of about 150 knots and the high speed of about mach 3 and every speed in between you'll see that the back half of the canard is a flap having a canard on the fore part of the airplane solves the problem of putting flaps on an extreme delta wing design so what about the windshield on this airplane well it's got unique features as well for supersonic flight a completely flat profile is necessary so the outer windscreen on the xb70 is a kind of ramp that that transitions up and down at slow speeds it can transition down into the nose to give the pilots a forward view but at high speed that outer windscreen comes back up and covers the inner wind screen so the crew compartment is completely isolated from that and the outer windscreen is only for aerodynamic purposes let's talk about wheels this is the front gear of the xb70 these tires are made by bf goodrich and you'll notice that they're silver not many tires or silver bf goodrich developed a special heat resisting compound that's infused throughout the body of the tire and also painted on its surface to make these tires withstand temperatures up to 360 degrees fahrenheit it's made possible by that silver painted compound on them which is also infused throughout the body of the tire the tires in turn are cooled up in the wheel well by a mixture of ethylene glycol circulating through braised tubes inside the wheel well so they're cooled by the surface of the tire and they're cooled inside the aircraft so here's the rear bogeys of the xb70 where the main tires are the tires are the same as on the front but check out this little tire here this little one is about anti-skidding that tire doesn't have any temperature protection because it doesn't need it what it does is it tells the computers inside the airplane when to apply the brakes and how much the brakes by the way on this airplane withstand up to about 2000 degrees fahrenheit temperatures there was an incident once landing one of these airplanes where these bogies didn't work like they were supposed to the whole thing pivots front to back so that the back tires hit first and then the front tires well one time one of the bogeys didn't pivot right and so the back half of one of the bogeys was severely damaged didn't lose the aircraft though compression lift is a key feature of xb70 aerodynamics the area of the shockwave formation on this airplane which is just at the front of the intake splitter duct on the underside of the fuselage and wings creates a shock wave that increases lift in this airplane by as much as 30 percent it also creates a reduced drag condition and enables the airplane to cruise quickly at mach numbers at a lower angle of attack saves fuel increases speed decreases drag so compression lift is a key component of the aerodynamics of this airplane another key part of xb70 aerodynamics is variable geometry wingtips these things over here at low speeds landing taking off and so on the wings are perfectly flat perfectly flat no anhedral no dihedral but at low altitude low supersonic speeds those wing tips can fold down at 25 degrees that increases the stability of the airplane makes it easier to control at high speed high altitude those wing tips fold down to 65 degrees not only does that solve stability problems but miraculously it also increases lift so the variable geometry of this airplane both increases lift provides stability and allows an airplane like this to operate in a wide range of speeds between 150 knots and about mach 3. it's really an amazing design feature another thing about the fold down wing tips is that at high supersonic speeds because they provide extra stability they allow the relative size of the twin upper fins the vertical fins to be that much smaller thereby reducing drag this is all very clever design solutions to high-speed supersonic flight in the 1960s riding your own shock wave is a feature of this airplane that compression lift holds the airplane up of course or provides like 30 percent greater lift than it otherwise would if the shock wave didn't exist and also the fold down wingtips increase that lift in addition to providing stability they allow the vertical fins on the top of the airplane to be that much smaller proportionally which in turn reduces drag so it's all part of a very clever design solution that all works together through some variable geometry to make this airplane a unique aerodynamic specimen one of the most amazing features of the xb70 that you can see here in the museum is the business end of the raw power of this jet at the back of the aircraft you can stand here and marvel at the six six side by side general electric yj93 after burning turbo jets now the aircraft could achieve mach 3 even if one of the engines wasn't working with only about a seven percent loss in range but the bottom line for these engines is that they operate best at very high speeds they operate in continuous after burner and so they're most efficient at super high speeds and joining six of them together in a row like this is nothing but high speed power each one of these engines develops a maximum of about 30 000 pounds thrust each of those engines actually was developed as well a single engine for another single engine fighter project which was canceled but putting six of them together same engine gives this airplane its tremendous speed you can see modern examples of something like this for example today's b1b has four of the same approximate types of engines that the single engine f16 fighter has so think of a b1 in terms of power as about four f-16s same with this thing it's got six fighters worth of power this is the guts of the xb70s power this is general electric's yj-93 after burning turbo jet this engine weighs a little more than two tons and develops a maximum of about thirty thousand pounds thrust it's got an eleven stage compressor and a two-stage turbine one of the unique things about this engine unique for the time anyway is that the afterburner though it looks like any afterburner is not controlled through cable linkages this afterburner is controlled electronically because you've got six of them to control that's a big task for any pilot and so think of six of these two ton engines together each developing thirty thousand pounds of thrust and you get a really really fast big airplane like the xb70 an interesting part of the trailing edge of the xb70s wings is the series of elevons combination ailerons and elevator along the trailing edge of both wings these are for latitudinal and longitudinal stability and it was designed with these trailing edge elevons to be split into six segments on either side of the engine bay and they're operated by no fewer than 24 separate hydraulic jacks by the way the elevons are operated only hydraulically there's no manual reversion for the pilot if the hydraulics fail but again they operate as elevator and aileron both flaring to land you're looking at the sky so no wonder these guys were the hottest pilots around you try and fly this crazy shape that you know it's elegant it's sleek it's great but it's got to be really difficult to steer in addition to the airplane being tricky and exotic to fly think about maneuvering the xb70 on the ground think about where the pilot is and where the front gear is the pilot is something like 60 feet in front of the gear so trying to turn the xb70 is like i don't know trying to turn a diving board that you're sitting on the end of it's got to be very tricky because the wheels back there and you are out here in front turning so you're just swinging across this arc the wheels way behind you that had to be hard to do it was a complex airplane like other airplanes of its era it was full of analog dials and gauges and so every pilot knows that there's a kind of a habit a system of scanning the instruments to make sure that everything's okay well think of that job inside the xb70 six engines a flight regime anywhere from 150 knots to mach 3 with high-speed crews at mach 2 or mach 3 preferable for the airframe in the engines plus you've got a control system that is dependent on these forward canards elevons in the back folding wing tips and so on so this is not your average airplane to fly it was perhaps a little tricky and unusual however the seven people who flew that aircraft were well acquainted with unusual flying situations in unusual vehicles so it wasn't a big surprise for them but it would probably overwhelm the rest of us the crew accommodations in the xb70 might not be what you'd expect you might think wow in such a fast high altitude airplane they're going to be wearing spacesuits well not so the xb70s crew cabin was air conditioned in a shirt sleeves environment the temperature in there at any speed was something between 70 and 100 degrees fahrenheit so it was a shirt sleeves environment however if they experienced decompression at high altitude each of the crew members the pilot and co-pilot they each had a separate kind of clam shell enclosure very similar to the one in the b-58 that would automatically close and then from inside of that pressurized enclosure the pilots could monitor the instruments through windows in this little clam shell and they could bring the aircraft back down to a safe altitude they had controls inside the little clam shell once they were at a safe altitude they could open the clamshell back again now if they had to eject from the airplane the whole clamshell both of them would come out of the airplane out of the top like an ejection seat one of the most interesting technological facets of the xb70 program was its steel honeycomb structure advances in the art of steel making realized in the xb70 program were especially notable it was principally a steel airplane it represented the first widespread use of stainless steel in a honeycomb panel structure the panels of the airplane which are comprised of facing sheets of steel brazed onto a honeycomb like core make up 22 000 square feet of the surface of the airplane this kind of honeycomb style stainless steel was carried out by the armco steel corporation of middletown ohio and we've got a honeycomb panel on display that you can see that was made by aranca incorporated but these honeycomb steel panels are an important part of xb70 technology and an important legacy to the art of steelmaking and aerodynamic structures 69 percent of the airplane's 150 000 pound weight is this welded stainless steel honeycomb sandwich it covers the wings from tip to tip it covers the engine box and the center fuselage and the fins and the rudders and the forward part of the canards most of the forward fuselage an aft plane is built up from titanium alloys so here's an airplane that's mostly stainless steel but also titanium these things also make it very very unusual in the 1960s and make it exotic even today the second xb70 was a tragic loss in the summer of 1966 it was flying a photo mission it was being photographed with two chase aircraft one of them was an f-104 but the f-104 collided with the xb70 in mid-air and its pilot was killed immediately and the xb70 its wing was damaged and both vertical stabilizers were gone and it flew on for only a couple of seconds before it became uncontrollable and its co-pilot major carl cross died unfortunately and the north american pilot al white ejected from the xb70 but he was badly injured but that's how the airplane was lost that's why there's only one xb70 now the base support for the xb70 was all at edwards air force base in california big air force testing center they had all the facilities super long runways all the rest of it and the only time that an xb70 ever landed anywhere else was when our xb70 landed here at right field the museum got its xb70 which was the first one made and the only one that exists now in 1969 the talents required to design the xb70 included both talent and persistence the airplane was designed without the kind of super computer modeling that we're used to having today where we know exactly how aerodynamic flow works because we can simulate it inside of a computer at millions and millions of operations per second well in the 1950s airplanes were designed with a decent knowledge of how aerodynamic flow works but testing the real article was the proof of how it was actually going to work so all of the the crazy geometry of the xb70 the forward canards the elevons the slightly smaller than you'd expect vertical surfaces the hugely swept wings the the wing tips that that fold downward in high speed flight all of that variable geometry is the result of people thinking through high-speed aerodynamic problems and then also thinking through the requirement for the airplane to take off and land at a relatively low speed so you've got the windscreen the canopy that pivots so that at high speed it's a flat surface but at low speed the pilots can still see out you've got the kenards acting as flaps you've got the splitters in front of the engine creating a place where compression lift comes into play massively increasing the lift of the airplane you've got all the fuel management for six very powerful engines that operated on afterburners all the time you've got the wings that pivot at the tips depending on the speed and by the way you've got tires every airplane needs tires while special tires on the xb70 were especially made to withstand heat the bogeys in the back had a little extra wheel as a skid sensor so that the brakes could be applied correctly because a big heavy airplane landing fast needs to have the brakes applied correctly and so all of these things all of these factors the engineering smarts required to create this airplane they all had to exist in the 1950s and those guys coming up with an airplane that looks sleek and futuristic even today is remarkable one thing that we emphasize among air force historians and museum curators and archivists is the differences and similarities between history and heritage there are two different things but they join hands and they join a couple of different professions together in presenting a picture of our past and making it relevant and interesting in the present so the history part is what happened what actually did happen and can you prove it and what are your sources the heritage part on the other hand is what do we believe is valuable enough about our past to pass on to the future it's our habits our stories our mythology in some cases what we're proud of the things we choose to tell people that we did and so with something like the xb70 we know about its technological history we know what it's made of who made it what they did with it its heritage is a story about technological progress and breaking barriers and crossing boundaries and making tools for the air force to use to protect the country that crossed technological boundaries and brought us the future that we live in now one of the most amazing factoids about the xb70 is that even though the airplane looks like the latest sleekest modern airplane it's two years older than the original star trek the airplane first flew in 1964 and captain kirk was not in orbit until 1966. one of the notable personalities connected with the xb70 is lieutenant colonel fitz fulton he made 63 flights in an xb70 and had the most flight time of 124 hours in xb70a the one that we have here he worked for both the air force and for nasa and he is an enshrinee of the national aviation hall of fame one of the reasons i think that the xb70 is such a popular airplane with museum visitors and with visitors online is not just because of its technical features but because it is a flat out beautiful airplane it's attractive and balanced in every way there's nothing ugly about that airplane it just says speed elegance and high technology it's always been like that you can see the xb70 and hundreds of other interesting exotic and historic aircraft here at the national museum of the us air force and if you can't get here immediately you can go on our website and see all the same stuff and you can even get inside the cockpits with our cockpit 360 application where you can look around the inside of these airplanes including the xb70 so i encourage you to visit and to visit our website

Channel: National Museum of the U.S. Air Force

Views: 420,586

Keywords: XB70, XB-70, North American XB-70 Valkyrie, avgeek, engineering, aviation history, bomber aircraft, experimental

Id: qqiulpdUgro

Length: 23min 36sec (1416 seconds)

Published: Wed Jun 30 2021