Speaker 1: Get in touch with technology with tech Stuff from how
Speaker 1: stuff Works dot com. Hey there, and welcome to tech Stuff.
Speaker 1: I'm your host, Jonathan Strickland. I'm an executive producer with
Speaker 1: How Stuff Works and I love all things tech and
Speaker 1: listener Ivan wrote into me and asked if I might
Speaker 1: record an episode about space planes. So today and tomorrow
Speaker 1: we're going to learn about space planes, because it turns
Speaker 1: out it's a big enough topic to warrant two episodes.
Speaker 1: We're gonna learn more or less how they work, why
Speaker 1: anyone was interested in building them, and some of the
Speaker 1: past and current projects that fall into that category. So
Speaker 1: to begin with, what the heck is a space plane? Well,
Speaker 1: like most stuff that has to do with space exploration,
Speaker 1: it's complicated. The general concept, if you're going super super
Speaker 1: high level, is that a space plane is a vehicle
Speaker 1: that can go into space, not necessarily into orbit, but
Speaker 1: at least into space and return to Earth, and it
Speaker 1: can fly under its own power. That's in contrast with
Speaker 1: other space vehicles like the Apollo or the soy US.
Speaker 1: Those have the tried and true methodology of ballistic re entry,
Speaker 1: also known as plummeting towards Earth under the force of
Speaker 1: gravity and then deploying a parachute to slow you down,
Speaker 1: and in the case of the soy Us, also having
Speaker 1: a quick blast of a retro rocket before you touch down,
Speaker 1: either in the ocean or on terra firma. A space
Speaker 1: plane would re enter Earth's atmosphere and then use the
Speaker 1: principles of powered flight or powered gliding to land at
Speaker 1: a designated landing strip, so they could actually not just
Speaker 1: control their descent, but steer and and go to a
Speaker 1: specific location for landing. This is actually way more complicated
Speaker 1: that I'm letting on at this stage, because you have
Speaker 1: to remember the principles of flight in space are very
Speaker 1: different than the principles of light. Here in the atmosphere
Speaker 1: of Earth. You have a fluid dynamics that work when
Speaker 1: you're flying through an atmosphere, and then you have the
Speaker 1: near vacuum of space when you're out in space. So,
Speaker 1: despite what science fiction films like Star Wars would have
Speaker 1: us believe, you wouldn't bank in outer space because there'd
Speaker 1: be no atmosphere for you to bank off of. In
Speaker 1: addition to these basic concepts I've just mentioned, we tend
Speaker 1: to tie to other things to the idea of space planes.
Speaker 1: One is that they should be reusable, meaning that you
Speaker 1: would refurbish a space plane after it's gone on a mission,
Speaker 1: and then you could use that exact same vehicle and
Speaker 1: a future mission, and that cuts down costs because you
Speaker 1: don't have to build a whole new one. The second
Speaker 1: big thing is that they should be easy and by
Speaker 1: that I mean cheaper to launch into space compared to
Speaker 1: other spacecraft. That's ideal. If you can figure out a
Speaker 1: way to make it easier to launch these types of
Speaker 1: spacecraft into space, you again bring down the cost of
Speaker 1: getting stuff into space. Under these general guidelines, you could
Speaker 1: say the space Shuttle qualifies as a space plane that
Speaker 1: totally is a type of space plane. It was reusable,
Speaker 1: it could return to Earth and powered glide so it
Speaker 1: can navigate to a specific landing strip. But the history
Speaker 1: of space planes dates way earlier than the Space Shuttle program.
Speaker 1: Perhaps the earliest design for a space plane would be
Speaker 1: the Silver Focal or silver Bird design. This was a
Speaker 1: proposal that dated in to the nineteen forties and it
Speaker 1: was in Germany during World War Two. The design was
Speaker 1: essentially a liquid fueled rocket that had some wings attached
Speaker 1: to it that was meant for a German pilot to
Speaker 1: fly up high into the atmosphere, essentially entering into what
Speaker 1: we would consider to be space, but not orbit. It
Speaker 1: would be a suborbital flight then to cross the Atlantic
Speaker 1: Ocean and descend in a a powered glide to attack
Speaker 1: a target in America like New York City. Now, while
Speaker 1: the Germans built some mock ups of this design, including
Speaker 1: one to use in wind tunnels, to make sure that
Speaker 1: the actual physical design of the body made sense, ultimately
Speaker 1: engineers concluded that it was too complicated to advanced to
Speaker 1: make practical. They just weren't quite there technologically to make
Speaker 1: it a practicality. But we'll revisit this concept shortly. In
Speaker 1: the nineteen fifties, a British engineer named Terrence non Wiler
Speaker 1: proposed an interesting concept called wave riding that would find
Speaker 1: its way into various space plane proposals. That started with
Speaker 1: a wing design called the carrot wing, which is a
Speaker 1: wing that has a type of concave pyramids shape to it.
Speaker 1: Non Wiler worked out a physical design that would allow
Speaker 1: an aircraft traveling at supersonic speeds to leverage the shock
Speaker 1: waves it was actually generating and use that as a
Speaker 1: lifting surface, which to me is incredible. That actually everything
Speaker 1: that has to do with supersonic and hypersonic flight physics
Speaker 1: to me is amazing. So what does that actually mean?
Speaker 1: Was a shock wave? Why do those things happen? Well,
Speaker 1: shock wave is a phenomenon that happens with really any
Speaker 1: type of wave, but we're specifically talking about sound waves here.
Speaker 1: When in a flow moves higher than the speed of
Speaker 1: sound in a given medium, and by flow I typically
Speaker 1: mean an object like an aircraft, but it could be
Speaker 1: other things. In fact, it could even be um the
Speaker 1: air itself moving faster than the speed of sound. So
Speaker 1: a cracking whip generates a small shock wave, a small
Speaker 1: little sonic boom type thing at the tip of the
Speaker 1: whip because it moves faster than the speed of sound
Speaker 1: when you crack it. So when you hear someone crack
Speaker 1: a whip, that means the very tip of that whip
Speaker 1: when it made that snap, was traveling faster than the
Speaker 1: speed of sound was. So let's get an understanding what's
Speaker 1: going on from a physics point of view. First, when
Speaker 1: something makes a sound, it's a physical phenomenon, right, It's
Speaker 1: it's the changing of pressure of uh air. Essentially air molecules.
Speaker 1: It's pushing them together or creating gaps and thus creating
Speaker 1: kind of a vacuum between them, and this propagates outward
Speaker 1: from the source. So we can visualize the sound wave
Speaker 1: as a sphere that's moving outward from something that's making
Speaker 1: the noise. So you've got a central object. Let's say
Speaker 1: it's a boom box or I guess if you guys
Speaker 1: don't know what a boom boxes, it's a it's a stereo,
Speaker 1: it's a radio, it's a it's a it's a smartphone
Speaker 1: playing Bruno Mars, it's playing music really loud, and the
Speaker 1: sound will travel out from a sphere from this central point. Technically,
Speaker 1: it travels out in all three dimensions, although obviously if
Speaker 1: you're playing something near the ground, it's gonna be bouncing
Speaker 1: off the ground at some point. But the sphere size
Speaker 1: increases at the rate of the speed of sound, right,
Speaker 1: because sound is traveling outward at the speed of sound,
Speaker 1: and gradually the that sound wave gets weaker and weaker
Speaker 1: as it propagates further and further out from the objects.
Speaker 1: So the further out you are from the object making sound,
Speaker 1: the quieter it's going to be to you. As the
Speaker 1: object continues to make sound, it's making more and more
Speaker 1: sound waves, so they're they're moving outward in this series
Speaker 1: of spheres that are growing out from the center of
Speaker 1: this sound storm. So we typically will illustrate this in
Speaker 1: a two dimensional format. It's much easier to understand that way.
Speaker 1: So you would just put a central point that would
Speaker 1: represent whatever the object is it's making sound, a stationary
Speaker 1: sound source, and you would surround that with a series
Speaker 1: of concentric circles and uh that suggests a sound wave
Speaker 1: that's traveling outward from that source, and it's a series
Speaker 1: of sound waves, actually, each concentric circle being another sound
Speaker 1: wave in this progression. So the further out you are
Speaker 1: from the object, the closer you are to the largest
Speaker 1: part of that of those circles. At this stage where
Speaker 1: you have an object making noise and it's stationary, all
Speaker 1: of the sounds are moving outward from the source and
Speaker 1: an equal rate of speed hitting things that are equidistant
Speaker 1: from the object at the same time. So if you
Speaker 1: were standing five ft to the right of the object,
Speaker 1: I'm standing five feet to the left of the object.
Speaker 1: The object is perfectly still. We're both gonna get hit
Speaker 1: by those sound waves at the same time we are equidistant.
Speaker 1: Sound is traveling at a uh standard speed and which
Speaker 1: is dependent upon the pressure and temperature and some other
Speaker 1: stuff in the air, but it's going to be traveling
Speaker 1: at that same speed through that medium. We're gonna hear
Speaker 1: at the same time. If I'm standing ten ft away
Speaker 1: and you're standing five feet away, it's gonna take longer
Speaker 1: for those sound waves to hit me then hit you.
Speaker 1: Not a whole lot longer, because the speed of sound
Speaker 1: is pretty fast, but technically it'll take a little longer
Speaker 1: to hit me than it does to hit you. If
Speaker 1: the object isn't stationary, then the picture changes a little.
Speaker 1: So imagine you've got a graph to show off sound
Speaker 1: in this way. Right, you're just looking at a graph.
Speaker 1: You've got a point that represents an object, and then
Speaker 1: you would draw circles around it to represent the sound
Speaker 1: waves emanating outward from that object. Well, if you were
Speaker 1: to imagine that this object is moving, let's say it's
Speaker 1: moving in a straight line towards the right side of
Speaker 1: the graph, if you wanted to represent the sound waves
Speaker 1: of circles, Now those circles would be offset. They would
Speaker 1: no longer be centered around that point. The point would
Speaker 1: be closer to the right side of those circles. The
Speaker 1: circles would be bunched up a little bit on the
Speaker 1: right and spread out a little bit on the left. Uh.
Speaker 1: You can think of it as like a stack of
Speaker 1: plates where you've shifted all the plates over, like each
Speaker 1: plate is slightly smaller than the one under it, and
Speaker 1: shifted them all over to the right a little bit.
Speaker 1: This means that if you were standing in the path
Speaker 1: of that object, as it got closer to you, as
Speaker 1: you would hear the sound, you would hear it at
Speaker 1: a higher pitch the sound waves. The wavelength between the
Speaker 1: sound waves has been compressed. That means it comes in
Speaker 1: at a higher frequency or a higher pitch as we
Speaker 1: would perceive it. Then when the object would pass because
Speaker 1: the sound waves are further apart from each other, that
Speaker 1: would come in as a lower pitch. This is the
Speaker 1: Doppler effect. So that's that now sound you always hear
Speaker 1: when something's coming at you and then passes you very quickly.
Speaker 1: If the object is moving at the speed of sound,
Speaker 1: then all the sound waves get compressed at that point
Speaker 1: of where the object is as it's moving. Uh. You know, again,
Speaker 1: if we say it's moving in a straight line to
Speaker 1: the right, all the edges of all the circles are
Speaker 1: overlapping right there at that point. This is the point
Speaker 1: of the shock wave. So let's say you can see
Speaker 1: this object. It's coming towards you. It's not at you yet,
Speaker 1: but you can see it. When you see it, you
Speaker 1: would not hear it make any sound because it's moving
Speaker 1: just as fast as the sound it is generating, so
Speaker 1: you won't hear it until it gets to you. And
Speaker 1: when it gets to you, all of those compressed waves
Speaker 1: would hit you at the same time. This is a
Speaker 1: sonic boom. It's when all the sound that would have
Speaker 1: been spread out as the object got closer to you
Speaker 1: has hits you, hits you all at once, so all
Speaker 1: those waves hit you simultaneously, and you get the sonic boom. Now,
Speaker 1: if the object is actually moving faster than sound, then
Speaker 1: it has behind it a cone of sound waves. The
Speaker 1: object is no longer even making contact with those circles.
Speaker 1: If we're if we're to draw it on a graph,
Speaker 1: you would have an object to the right and a
Speaker 1: series of circles that are semi overlapping and getting larger
Speaker 1: and larger as you go further to the left, and
Speaker 1: if you were to draw enough of them and then
Speaker 1: draw lines on either side, you would see this makes
Speaker 1: a cone shape. It's actually a three dimensional conical shape
Speaker 1: spreading in all directions. The faster the object is going,
Speaker 1: the pointier the cone is going to be. When that
Speaker 1: cone makes contact with a listener, that's when the listener
Speaker 1: would hear the shock wave or experience the shockwave the
Speaker 1: sonic boom, So the object would actually pass the person
Speaker 1: completely before the person would hear the sonic boom. In
Speaker 1: this case, because the objects moving faster than sound is
Speaker 1: uh that cone will trail behind the object as long
Speaker 1: as it's traveling at this speed, So if you're in
Speaker 1: the path of the cone, you'll hear the boom once
Speaker 1: the cones border crosses you. If you could then immediately
Speaker 1: teleport ahead of the traveling object so that the cone
Speaker 1: would pass over you again, you would hear it again
Speaker 1: once it passed over you. The so the cone represents
Speaker 1: the crests of many waves of sound, and also within
Speaker 1: that cone, you have a rapid change of air pressure
Speaker 1: and temperature, meaning any air vehicle that's going to be
Speaker 1: traveling at the speed of sound or greater has to
Speaker 1: be able to handle these major changes in those factors.
Speaker 1: NASA is currently working on developing a low boom supersonic aircraft,
Speaker 1: which will use special aircraft shapes meant to limit the
Speaker 1: intensity of the sonic booms they will generate, but that's
Speaker 1: a topic for a future episode. In the then Soviet Union,
Speaker 1: two engineers created a design later called the v K
Speaker 1: A Maya ziv Chev And I know I've totally butchered that,
Speaker 1: but you know, you've got to kind of roll with it.
Speaker 1: It was also known as the M forty eight. Uh.
Speaker 1: It was designed to be a really tiny, one person
Speaker 1: space plane that would use an ICYB M as the
Speaker 1: launch vehicle. So how tiny am I talking about? Well,
Speaker 1: it was supposed to be eleven point four feet tall
Speaker 1: or three and a half meters and have a wingspan
Speaker 1: of twelve point four ft or three point eight meters,
Speaker 1: and it would weigh two thousand, two hundred pounds or
Speaker 1: a thousand kilograms. That spacecraft was never built. Several other
Speaker 1: designs would follow, but they two remained almost just completely
Speaker 1: in concept mode. Well, only a few ever reaching the
Speaker 1: earliest stages of prototypes. None flew at that time, the
Speaker 1: so Union would instead focus on ballistic based re entry vehicles,
Speaker 1: not not flying ones. In the United States, NASA has
Speaker 1: a series of air and spacecraft that fall under the
Speaker 1: designation of the X series, and that stands for experimental.
Speaker 1: These are vehicles that are meant to test designs and
Speaker 1: technologies that might be implemented in future aircraft or rockets
Speaker 1: or spacecraft. It's a testing bed for those technologies. The
Speaker 1: X one, fittingly was the first of those vehicles. And
Speaker 1: while the X one was not a space plane, it
Speaker 1: was an important aircraft. For one thing, the X one
Speaker 1: would become the first aircraft to break the sound barrier.
Speaker 1: It was also a purely experimental craft. There were no
Speaker 1: commercial or military or requirements attached to it, so NASA
Speaker 1: was able to focus just on creating the machine that
Speaker 1: would do what they wanted it to do. They didn't
Speaker 1: have to worry about any other cerns and it would
Speaker 1: be up to later designers to incorporate that technology into
Speaker 1: practical aircraft. And I'll have to do a full episode
Speaker 1: on the X one in the future. It is a
Speaker 1: fascinating story, but for our purposes, the important thing to
Speaker 1: keep in mind is that set the stage for later
Speaker 1: experimental aircraft, including some that were essentially prototypes of practical
Speaker 1: vehicles further down the road. I'll tell you about them
Speaker 1: in just a second, but first let's take a quick
Speaker 1: break to thank our sponsor. There have been many different
Speaker 1: X vehicles. All of them were meant to work on
Speaker 1: different designs and strategies like wing shape, aircraft, material, power systems,
Speaker 1: propulsion systems, and experimental techniques like vertical takeoff and landing.
Speaker 1: And to be honest, most of those have contributed in
Speaker 1: some way or another toward the development of space planes,
Speaker 1: either directly or indirectly. But if I were to go
Speaker 1: down the whole list and explain each one, we would
Speaker 1: have at least another week's worth of episodes to get through.
Speaker 1: So I'm just gonna hit some of the highlights that
Speaker 1: I feel are particularly relevant. But please keep in mind
Speaker 1: this is like the cliffs Notes version of space plane history.
Speaker 1: The X fifteen was a hypersonic research jet plane program
Speaker 1: NASA partnered with the U. S. Navy, the US Air Force,
Speaker 1: and a company called North American Aviation Incorporated. The aircraft
Speaker 1: traveled at a top speed of four thousand, five hundred
Speaker 1: twenty miles per hour. That's seven thousand, two hundred seventy
Speaker 1: five kilometers per hour, also known as mock six point
Speaker 1: seven well also known as is being too glib and
Speaker 1: not entirely accurate, because mack is a way of expressing
Speaker 1: speed in relation to the speed of sound moving through air. Now,
Speaker 1: this gets a little complicated because, like I said earlier,
Speaker 1: sound will travel at different speeds depending upon different factors
Speaker 1: like air temperature. So sound moves at a at one
Speaker 1: speed through cold air and a different speed through warm air.
Speaker 1: And that's because sound is a physical phenomenon and involves
Speaker 1: vibrating molecules. But the mock number actually takes that into account.
Speaker 1: The mock number is the ratio that describes the speed
Speaker 1: of a given thing. Typically we call it flow, but
Speaker 1: again it could be an object, uh and within an environment.
Speaker 1: So in this case, we're talking about aircraft, and you
Speaker 1: compare that with respect the speed of sound within the
Speaker 1: same medium under the same conditions. So if I say
Speaker 1: an aircraft travels at MOCK one, I wouldn't be saying
Speaker 1: that it's going just as fast as the speed of
Speaker 1: sound within that medium, meaning the air that the aircraft
Speaker 1: is traveling through. Now, the one I just mentioned before,
Speaker 1: the X fifteen was mock six point seven. That means
Speaker 1: that the X fifteen could travel up to six point
Speaker 1: seven times faster than the speed of sound through that
Speaker 1: same medium, which is wicked fast. There were three X
Speaker 1: fifteen rocket planes collectively, they flew one hundred ninety nine times.
Speaker 1: The X fifteen did not take off on the ground
Speaker 1: on its own, nor was it launched via rocket. Instead,
Speaker 1: it would launch from a B fifty two aircraft at
Speaker 1: around an altitude of forty five thousand feet there's about
Speaker 1: thirteen thousand, seven sixteen, and the B fifty two would
Speaker 1: be traveling at a speed of around five hundred miles
Speaker 1: pur or eight hundred five kilometers per hour. The highest
Speaker 1: altitude the X fifteen ever reached, according to NASA, was
Speaker 1: three fifty four thousand, two hundred feet that's sixty seven
Speaker 1: miles or one eight kilometers. The Carmen line, which most
Speaker 1: of the world acknowledges as being the border line for
Speaker 1: Earth's atmosphere and space, is generally in the one kilometer
Speaker 1: altitude range, So the X fifteen reached altitudes of suborbital space,
Speaker 1: so you could argue the X fifteen qualifies as a
Speaker 1: space plane, but one that was meant purely to conduct
Speaker 1: research for future vehicle designs. Following the X fifteen was
Speaker 1: a project called the Dina sore d Y in a
Speaker 1: Dash s O A R, also known as the X twenty.
Speaker 1: NASA contracted Boeing to build the space plane. There was
Speaker 1: a related asset called Asset. This was sort of the
Speaker 1: nose cone section of the dinosaur. It was used separately
Speaker 1: to test various designs to find out what sort of
Speaker 1: shielding would best withstand re entry and the rigors that
Speaker 1: any material would undergo as it does re enter the
Speaker 1: air's atmosphere. The Dinosaur was in parallel development in some
Speaker 1: ways to the X fifteen that it would take advantage
Speaker 1: of lessons learned from the X fifteen program, and it
Speaker 1: also had links back to the silver Vogel aircraft proposed
Speaker 1: in Germany. There was a man named Walter Dornburger or
Speaker 1: Valter Dornburger. He was one of the key figures in
Speaker 1: developing the Dinosaur project. He was in charge of Germany's
Speaker 1: rocketry program in World War Two. He was also the
Speaker 1: direct superior to the famous rocket scientist Verna von Brown.
Speaker 1: He wasn't picked up by the United States during Project
Speaker 1: paper Clip. That was the secret project in which the
Speaker 1: United States out over a whole bunch of German scientists
Speaker 1: to work on the same stuff they had been doing
Speaker 1: over in Germany, but now for the United States. Dorn
Speaker 1: Burger instead go into British custody for a few years
Speaker 1: before being released and then immigrating to the United States,
Speaker 1: where he found a job with Bell Aircraft. He advocated
Speaker 1: that the company tried to make real the vision of
Speaker 1: the Silver Vocal. Dorn Burger felt that rockets were the
Speaker 1: future of flight, even for commercial flight, though probably just
Speaker 1: for the really wealthy, and it would become the propulsion
Speaker 1: systems for a new type of aircraft that he would
Speaker 1: call ultra planes. These were essentially very similar to what
Speaker 1: we would think of as space planes, and dorn Berger
Speaker 1: imagined a world in which a hypersonic glider would ride
Speaker 1: piggyback on a larger rocket propelled aircraft. At the appropriate altitude,
Speaker 1: the glider would launch off of rails that were mounted
Speaker 1: on this booster vehicle and ignite its own rocket propulsion system,
Speaker 1: which would push this smaller vehicle to great speed and
Speaker 1: higher altitudes. At the peak of its journey, It would
Speaker 1: then switch off its engines and then glide quietly to
Speaker 1: its destination. The booster vehicle would return home for the
Speaker 1: next journey up, and this idea would coalesce into a
Speaker 1: program that was called Dinosaur. As one of several proposals
Speaker 1: that entered into debate during the Round three conference, which
Speaker 1: took place just eleven days after the Soviet Union had
Speaker 1: successfully launched Spot Nick one into orbit. Dinosaur, which originally
Speaker 1: was pitched as a dual research and military platform that
Speaker 1: could potentially be weaponized, was able to move into the
Speaker 1: next stage of development. The program was actually revised multiple times,
Speaker 1: and this complicated the process of designing and prototyping because
Speaker 1: whenever you change the requirements, it changes lots of other
Speaker 1: stuff down the line. One late edition was a feasibility
Speaker 1: study to make sure that the Dinosaur could also serve
Speaker 1: as an orbital vehicle, sort of like what the Space
Speaker 1: Shuttle would eventually become. Then in September, the United States
Speaker 1: SARA Force General Bernard A. Shriver changed things up big
Speaker 1: time by stating the program would be split into two
Speaker 1: parallel arms. One of the versions of Dinosaur would be
Speaker 1: developed as a military application of the technology. The other
Speaker 1: would be intended for space faring projects, and a priority
Speaker 1: would be placed on No big surprise here the military one.
Speaker 1: Around this time, pilots were joining the program, including future
Speaker 1: astronaut Neil Armstrong. Armstrong was also given the task to
Speaker 1: figure out how to keep an astronaut safe in the
Speaker 1: event of a launch failure, such as a launch vehicle
Speaker 1: about to explode. Ejection was not an option because the
Speaker 1: dinosaur cockpit was only about a hundred feet above the
Speaker 1: ground in the design they had created. Once it was
Speaker 1: attached to a launch vehicle, and the pilot would be
Speaker 1: essentially on his or her back UH in a seated position,
Speaker 1: but they're facing upward right the dinosaur would be the
Speaker 1: nose of the vehicle would be pointing towards the sky.
Speaker 1: So there wouldn't be enough time if you ejected for
Speaker 1: the UH for your orientation to change and for the
Speaker 1: parachute to deploy, and so Armstrong had to come up
Speaker 1: with a different idea. His solution was to create a
Speaker 1: system that would actually engage the glider's engine and thus
Speaker 1: shoot it off of the booster rocket, launching the glider
Speaker 1: into the sky, and then the pilot would have to
Speaker 1: take control of this accelerating vehicle and stabilize it and
Speaker 1: then fly the glider to safety. He was able to
Speaker 1: do this using a simulated test with an actual jet airplane,
Speaker 1: and he said he was later on said that he
Speaker 1: was glad he never had to test it on an
Speaker 1: actual dinosaur because it was hard to do. It was possible,
Speaker 1: but you had to be a really skilled pilot, and
Speaker 1: you were subjected to some massive uh stresses as you
Speaker 1: did it. However, the course of nineteen sixty two, funding
Speaker 1: was pulled from the Dinosaur project, forcing it to scale
Speaker 1: back multiple times, and a night teen sixty three, the
Speaker 1: government formally canceled the project, largely because Project Mercury and
Speaker 1: then Jim and I were answering many of the questions
Speaker 1: that Dinosaur was meant to explore, and the ballistics model
Speaker 1: of returning astronauts safely to Earth was already proven to
Speaker 1: be successful. So if you've already got a way to
Speaker 1: get people back to Earth, why bother working on a
Speaker 1: different way. Just focus on the way that works for
Speaker 1: now and worry about the other one later. That seemed
Speaker 1: to be the philosophy. I've got more to say about
Speaker 1: early space planes, but first let's take another quick break
Speaker 1: to thank our sponsor. One of the other designs that
Speaker 1: I feel we need to talk about is the concept
Speaker 1: of the lifting body. A lifting body aircraft has, as
Speaker 1: the name suggests, a body that's meant to generate lift
Speaker 1: when the aircraft is flying through the air. The body
Speaker 1: itself does this. This is normally the job of an
Speaker 1: aircraft's wings, but with a lifting body aircraft, the body
Speaker 1: itself is behaving as if it's a wing. Uh. This
Speaker 1: idea dated back to the late nineteen fifties. There was
Speaker 1: an egghead named Dr Alfred JA Eggers Jr. Who was
Speaker 1: at the time the assistant director of the Research and Development,
Speaker 1: Analysis and Planning Department at AIMES Aeronautical Laboratory. Leading up
Speaker 1: to Egger's proposal was a lot of work surrounding missile
Speaker 1: nose cones. The problem focused on ways to create a
Speaker 1: nose cone capable of surviving aeronautical heating due to re entry.
Speaker 1: There was an engineer named H. Julian Allen who concluded
Speaker 1: that if you made a blunt nose cone rather than
Speaker 1: a sharply tapered one, it would better hold up to
Speaker 1: the forces it would undergo, specifically the temperatures when undergoing reentry.
Speaker 1: Eggers took this a step further. He found that if
Speaker 1: he modified this blunted nose cone shape slightly, the new
Speaker 1: shape would actually produce aerodynamic lift if the body was
Speaker 1: flying through the air fast enough. This design would mean
Speaker 1: a spacecraft would be able to fly back to Earth
Speaker 1: rather than to just plummet to Earth ballistic style. Egger's
Speaker 1: and his peers created a design called the M two.
Speaker 1: So imagine that you have a cone shaped like an
Speaker 1: ice cream cone, and then imagine that it's on its
Speaker 1: side right, so you've got the wide end on one side,
Speaker 1: the point end on the other, round off the point
Speaker 1: end a little bit, so it's not two point, it's
Speaker 1: a little dull. And imagine that the top half of
Speaker 1: the cone is now flat. It is no no longer
Speaker 1: rounded at the top, it's flat, and the bottom half
Speaker 1: is still round. That's generally the shape they were working with.
Speaker 1: They added in some stabilization fins towards the back of
Speaker 1: the vehicle that poked up on either side, and you
Speaker 1: have essentially the M two F one lifting body vehicle.
Speaker 1: This vehicle was an unpowered test vehicle. It would be
Speaker 1: towed behind other aircraft to test its aerodynamic capability, and
Speaker 1: it was unmanned. Obviously, later vehicles were built on that
Speaker 1: design and would incorporate an x l R eleven rocket engine,
Speaker 1: which was the same kind that is used in the
Speaker 1: X one supersonic jet. Several lifting body aircraft designs followed.
Speaker 1: I think the X A is perhaps the weirdest one.
Speaker 1: You need to take a look at that aircraft. If
Speaker 1: you can go to Google image search type of X
Speaker 1: dash to four A, you're gonna see what looks like
Speaker 1: a jet that's missing its wings. That's a lifting body aircraft. Now.
Speaker 1: The reason I even mentioned lifting body designs is that's
Speaker 1: what the Martin X twenty three Prime aircraft used, and
Speaker 1: that was the next big space plane. This was an
Speaker 1: air Force project in the mid nineteen sixties. Prime itself
Speaker 1: was an acronym. It stood for precision recovery including maneuvering entry,
Speaker 1: and this was to test a lifting body design in
Speaker 1: relation to re entering the Earth's atmosphere and being able
Speaker 1: to travel cross range up to eleven kilometers. That would
Speaker 1: mean the craft would be able to steer along a
Speaker 1: ballistics re entry path and land at a more precise location.
Speaker 1: It was mostly made out of a titanium alloy, and
Speaker 1: it weighed in at nearly eight two pounds or four legrams.
Speaker 1: It was an unmanned vehicle and they held three successful
Speaker 1: missions with the various ones. They had built five of them,
Speaker 1: but after three flights, the Air Force canceled the rest
Speaker 1: of the project, which left two X twenty three a's
Speaker 1: completely unflown. Those were sent off to the United States
Speaker 1: Air Force Museum at Wright Patterson Air Force Base. When
Speaker 1: Dinosaur got the AXE, the Air Force began to develop
Speaker 1: plans for space planes under the same umbrella project that
Speaker 1: the X twenty three A was under that was called Start.
Speaker 1: After the X twenty three project got the AX in
Speaker 1: nineteen sixty six, it would take nearly two decades before
Speaker 1: another space plane design would become a reality. That design
Speaker 1: would be the Space Shuttle, which debuted in nineteen eight one.
Speaker 1: I've talked about the Space Shuttle recently, so this will
Speaker 1: just be a super quick overview version. First of all,
Speaker 1: the design of the Shuttle is similar to the earlier
Speaker 1: lifting body spacecraft I've mentioned, though the Shuttle also had
Speaker 1: a double delta wing configu duration. This particular shape is
Speaker 1: efficient for hypersonic flight and was good at giving the
Speaker 1: Shuttle a good lift to drag ratio, so it wasn't
Speaker 1: a pure lifting body spacecraft. It also did have these
Speaker 1: wings in an earlier design before they actually had to
Speaker 1: commit to the final form of the Space Shuttle, it
Speaker 1: was supposed to launch off the back of a larger aircraft.
Speaker 1: The Shuttle would be kind of carried piggyback and would
Speaker 1: launch from that aircraft once it reached a certain speed
Speaker 1: and altitude, and then the Shuttle would make the rest
Speaker 1: of the journey up to low Earth orbit, But budget
Speaker 1: cuts at NASA forced engineers to switch to more conventional
Speaker 1: rocket style launch vehicles. The Space Shuttle would ultimately launch
Speaker 1: in a vertical position using a pair of enormous solid
Speaker 1: rocket fuel boosters that would provide most of the thrust
Speaker 1: at lift off. The three main engines on the shuttle
Speaker 1: itself would provide the rest of the thrust at liftoff.
Speaker 1: In Between the two solid rocket boosters was a huge
Speaker 1: external fuel tank that held the liquid hydrogen and liquid
Speaker 1: oxygen that would serve as the fuel for the main engines.
Speaker 1: The shuttle would first jettison the two booster engines about
Speaker 1: two minutes after a liftoff and then would later jettison
Speaker 1: the huge external tank. Once the shuttle would reach a
Speaker 1: velocity sufficient to insert into low Earth orbit, the booster
Speaker 1: engines could be recovered and reused. The external tank was
Speaker 1: not meant for reuse. At the conclusion of a Space
Speaker 1: Shuttle mission, the shuttle would fire its orbital Maneuvering System
Speaker 1: or o MS thrusters and leave orbit to re enter
Speaker 1: Earth's atmosphere. The shuttle relied heavily on arrow braking, in
Speaker 1: other words, too maneuver in such a way where the
Speaker 1: air itself is slowing the descent of the shuttle through
Speaker 1: the atmosphere, and it would do so until it reached
Speaker 1: the lower atmosphere, where the shuttle could fly as a
Speaker 1: powered glider. Between two thousand and eleven, the shuttles in
Speaker 1: the Space Shuttle fleet collectively flew on on five missions.
Speaker 1: Eight hundred thirty three people flew on a Space Shuttle mission,
Speaker 1: with some going multiple times. Fourteen people lost their lives
Speaker 1: and catastrophic accidents on the Space Shuttle program and the
Speaker 1: Challenger and Columbia disasters. The Space Shuttle program proved the
Speaker 1: utility of a space plane design a spacecraft that can
Speaker 1: maneuver both inside the Earth's atmosphere and an orbit is
Speaker 1: incredibly useful, particularly when you can fly the same spacecraft
Speaker 1: multiple times. The end of the space Shuttle program in
Speaker 1: two thousand eleven would not be the end of the
Speaker 1: space plane era. In the next episode, I'm going to
Speaker 1: talk about some of the other space plane designs, including
Speaker 1: a super secret one that I covered in an older
Speaker 1: episode of tech Stuff, And we'll learn about those and
Speaker 1: other space planes, including a design from the United Kingdom.
Speaker 1: So stay tuned for that. And if any of you
Speaker 1: out there have suggestions for future episodes of tech Stuff.
Speaker 1: Maybe it's a technology, a company, person in tech, anything
Speaker 1: like that, let me know. Send me an email the
Speaker 1: addresses tech stuff at how stuff works dot com, or
Speaker 1: drop me a line on Facebook or Twitter. The handle
Speaker 1: of both of those is tech Stuff H s W.
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Speaker 1: public dot com slash text stuff. And finally, we've got
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Speaker 1: follow that, won't you, and I'll talk to you again
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