Anna Maria McGowan
Air & Space Conference and Technology Exposition
September 26, 2006
"Morphing Technologies for Future Aircraft"
Ms. McGowan: Thanks, and welcome. For me to be here, this is really neat. I came last year. It was my first time at the AFA conference, and I said what on earth is an AFA? The Air Force folks I usually talk to are at the labs, so this is quite a unique experience for me.
I realize that about half of you came out of sick curiosity. What on earth is morphing and who has the guts to get up there and actually talk about morphing with a straight face? So Iíll be sure to entertain those who came out of sick curiosity as well.
I have a quick chart on acknowledgements. I work with a whole lot of folks all over NASA. NASA Langley, which is where Iím located, as well as at NASA Dryden, NASA Glenn, also with DARPA (Defense Advanced Research Projects Agency), with the Air Force, of course, Navy and Army. So Iím not the only person working in this strange area called morphing technologies. You will see some Air Force technologies in some of the charts that I have.
What is morphing, exactly? What on earth am I talking about? Why would you do it? Has it been done before? What has sort of happened in the last century of flight to make us get where we are today?
Obviously this is not easy, otherwise it would have already been done. So some challenges and lessons learned. Then Iíll talk a little bit about the future and close with a few remarks.
Iíll keep it informal. You can ask questions. Iíll leave some time at the end as well.
First of all, what is morphing? For a lot of folks morphing is Terminator 2, right? Itís the wings oozing out of the airplane, the wings are twisting and bending. Iíll start with what morphing is not. Itís not aliens and UFOs.
Every year I get an e-mail from somebody saying have you helped the green men at Roswell? My response normally is I certainly hope so, so just leave with that. But there actually are complete web sites assuming that NASA and the US Air Force have collaborated to actually help the aliens at Roswell, in all seriousness. But itís not that.
Nor is it airplane torture. We are not trying to take your perfectly good airplane and do evil things to it. Weíre not going to take the wings of a C-5 or a 747 and make them flap, that is not the idea of morphing, either.
So what on earth is it actually? Today airplanes change shape all the time. Many of you aviators in the room are very familiar with that. The F-14, variable sleeve wing. Even something as simple as leading and trailing flaps, landing gear, a variable incidence nose. Certainly today we already do things to make the airplane change shape or adapt to its environment, so itís not exactly a new science.
But morphing. We created this new word. It was probably the early Ď90s when it was created. What are we really talking about? There are three words that we use. Iíll start from the bottom and go to the top.
The first partís adaptability. Making the airplane much more versatile, much more resilient to a wide variety of flight conditions. Again, if youíre paying attention youíll say airplanes are already pretty adaptive.
The next part, multi-point. This is where it gets a little harder. Trying to accommodate very diverse and even sometimes contradictory mission scenarios. Trying to fly supersonically and subsonically with the same amount of efficiency, without burning a lot of fuel as an example. Long range strike efficiently. Iíll have several more examples in a little bit.
This last one is where it gets really challenging. More efficient. On the F-14 the variable sweep mechanism costs 5,000 pounds on the airplane. Thatís a lot of weight to add to an airplane. However, after a system study was done, those 5,000 pounds more than bought their way onto the airplane for the capability that the Navy got from that airplane. Now in the Air Force, of course, you donít want to pay that much, so to speak, for that capability.
So efficiencyís a big deal. Itís got to be either simpler, lighter, or more volume efficient.
Just for kicks, morphing in our everyday lives -- things like zip-off pants, convertibles, of course, and the weathermen.
So the cost of shape change. I mentioned one example. I want to show a chart. People always ask, is it worth it? Is it worth doing this dramatic shape change? Iíll challenge you later. The dramatic shape change isnít actually the goal of morphing, it is just one technology approach.
In this chart basically, these are mission requirements down here, and weight and cost of the system. So if you in a single mission fly fast, small payload fraction, et cetera. Not a lot of cost to that. However, if you want to do multiple missions, you basically have to size your wing to do everything you want that wing to do and itís going to cost you a lot. Itís going to be very heavy and very large. This is the weight penalty.
If you try to do more things and you want to grow to that so you can take all that junk away and become smaller when you need it, thatís great, but at your single mission condition this wing is going to cost you a lot, and thereís your penalty for that.
However, for your multi-mission scenario it actually saves you weight over having a fixed wing. Iíll even make this another example thatís perhaps more common. Retractable landing gear. Everyone knows that about 110, 120 knots, thatís where you have to have landing gear that retracts. Below that, it does not buy its way onto the airplane. Above that, it does. It costs a lot. It weighs a lot. If you're going to fly past 110, 120 knots, youíve got to have it on there and you will pay the weight penalty and the complexity penalty.
This is saying basically the same thing for morphing wings. You have to know if youíre going to design this into your system where that knee in the curve is and you want to be way out here when you do so.
The F-14, absolutely, at a single condition, a single condition, it certainly costs more, 5,000 pounds more. However, for the mission scenarios it wanted to go to it actually saved weight in the long run. So this is what weíre trying to do, working with folks just like yourself.
So morphing is a technical and a mission problem. Itís not required for everything, nor is it desirable, frankly, for all missions. Weíre not trying to do airplane torture.
A little bit of history. Iím always asked, has this been done before? Most of it was inspired by nature early on. Some have said well, the Wright Brothers turned and twisted their wings, and they did. Believe it or not, their inspiration was from birds. One of the biggest break-throughs the Wright Brothers made was actually studying the empanada or the tail section of a bird. The bird lands widely by twisting and bending its tail section. It cannot land very well if you cut the tails off. Even with the biggest wings, if the tails are gone it cannot do it. Nor can it do it if the tail stays fixed, by the way. It only takes moving a few tail feathers for it to be able to do so, so adaptability is a big deal to a birdís maneuverability and the Wright Brothers in fact pointed that out in many of their early studies.
Some more examples. Many of these were before several of us were born in this room. In 1914 Gallaudet had one example of wing tip.
This oneís interesting to me. The X-5. 1952. It actually flew, variable sweep airplane, 20 to 60 degrees. If you're taking notes, it was 20 years later before the F-14 came on-line. When this first flew, all the reports by both the Air Force and the Navy said thatís ridiculous. It costs too much, thereís no need for that, itís too complex, et cetera. Twenty years.
So when some of you at the end of this go sheís nuts, Iím going to say thanks. Iíll talk to you in 20 years.
Another example, the Goodyear. Goodyear made this airplane. Itís an inflatable airplane that flew back in the 1950s. Didnít fly very well, frankly. The idea was that if youíre stuck in enemy territory you pop this thing out, you blow it up and you take off and get out of there. 1950s.
The Fanassa Beach, 1969. Also a variable tip airplane.
Here are some movies. This is the oblique wing, 1980, which flew. Some of you are aware of this. DARPA has an oblique flying wing program right now and they are intending to build an oblique flying wing. However, in their program they wonít have a fixed fuselage as is here. The entire airplane is just pretty much a wing and the entire airplane will go oblique. DARPA is planning on doing those right now.
This other movie, the XB-70 Valcary. Variable span. A big behemoth, supersonic airplane that did have variable wing sections on it as well. 1964.
What has changed since then? The motivations are about the same. Youíre trying to improve performance and expand things, so what would you like to do? Some of these examples I got were from DARPA.
Combine ISR with attack. Right now your Global Hawk, you can put a few bombs on it but it doesnít fly as fast as youíd like it to do the attack as well as you would like it.
High speed response with loiter and attack on the same airplane. Long range attack as well.
Civilian examples. I have an example of a planetary explorer Iíll show you later, thatís kind of interesting. A Mars airplane concept.
Altitude, long endurance airplanes. We can make airplanes that are high altitude, long endurance. Look like this. These things do not take off very well at all. They canít handle gusts whatsoever, and the wings tend to rip off, frankly. So being able to build that airplane so that it can fly there and fly closer to earth well is a challenge.
This concept recently flew. Itís a quiet engine demonstrator. This is the tail end of an engine and these are called chevrons in the back end. It reduces noise substantially on takeoff and landing. The challenge was that at every other point in the flight regime these actually cost money and fuel to fly it. So smart materials, which Iíll describe in a minute, replaced on that to basically take these chevrons out of the way so they did not cost while youíre flying. Again, adapting the airplane to different flight regimes.
This again has already flown. It was a Boeing NASA, a million different people in on the thing.
The high lift system. Hereís another example. This is what Todayís high lift system looks like. This is where weíre going. Iíll show you an example of how we might get there.
So much of this morphing idea was inspired in the early Ď90s by a technology called smart materials. Iíll show you some examples of the smart material.
There are quite a variety. Itís a material that responds to a stimulus in a repeatable and controlled manner. Iíll break it down even simpler. If you have a dumb material like wood it carries weight very well -- itís strong, efficient, et cetera. However it doesnít do anything else but carry weight.
Smart material, and Iíll just take one called the piazo electric. When you apply a voltage it actually vibrates at the same frequency you apply the voltage to it. How thatís being used? It can be used to absorb noise, it can vibrate alternative to the noise source and reduce noise on an aircraft. It can control vibration on an aircraft.
Other smart materials. There are some smart materials out there that at one magnetism it is liquid, abiscus liquid like molasses. Then at a higher level of magnetism it becomes almost like cement, like you cannot even move it. Itís being used very well right now in prostheses joints, believe it or not, where a little bit of magnetism is wrapped around that material so it gets stiffer when the person is standing on stairs and then as theyíre jumping it becomes a little looser.
So there are hundreds of smart materials that have been discovered in the last 30 to 40 years and weíre just now figuring out how we can use those materials in airplanes, transistors, computers, even in biology. There are quite a lot of examples of using it.
Here is just one, to give you an idea. This material. This is an electro restrictive material. You apply a voltage and it literally can move back and forth on its own. You can spin them like fibers and make a muscle tissue that actually behaves and comes alive with electricity. Many of you are thinking Frankenstein. Yes. Itís very much like that. That was exactly my first reaction when I saw this stuff.
Some examples of this. These are materials that we stretch in the lab. Very flexible metal materials. A lot of folks have said well how would you ever skin a morphing system? Donít you need something flexible and strong? The answer is yes, and there are many concepts for doing just that. The problem certainly is not solved, but there are many studies underway.
Another example, this is a piazo electric material. This is the one that will vibrate and control vibration. At this point itís on skis, itís on bicycle, itís on spacecraft, itís on rotor blades. There are many different areas where these smart materials can be used.
So with the idea that you have new materials available to you and new computing available to you there have been a lot of what we call visions of morphing in the last decade. Iím showing you some silly pictures intentionally.
This was a vision we came up with in probably 1998, along with several other folks. Let me be clear. We donít know what tomorrowís morphing airplanes are going to look like. There are a lot of pictures out there that youíll see, and if history is any indicator, typically we dramatically under-predict or frankly, incorrectly predict how we will use a new technology. So Iím going to show you some interesting pictures but I am sure in 20 years we will have not gotten it right. That is exactly how technology works. No one predicted the laptop would be used the way it is, as an example.
So one picture of how you can take these materials and use them. This is a material called an electro-active polymer. Basically itís a very thin sheet of material. It looks exactly like saran wrap but it can respond to your breath, basically. So you can place it over top the wing of an airplane and it would sense rain, it would sense wind or anything else thatís going on there. Almost like a skin, basically, with very very little voltage, highly sensitive.
There are many other technologies on here I can show you.
To show you how international interest comes in this, I was sent this picture from a German newspaper a few years ago. I canít read German but the only thing I could read was Anna McGowan in here. I said good grief, what on earth is it saying about us? Whatís interesting is that in Europe, on a very serious note, they have put millions of dollars into looking at adaptable technology. Millions and millions of dollars. AirBus themselves, in fact, are funding many technologies for how to make an airplane fly more like a bird.
This image was created in 2001. I often get questions about this so I went ahead and brought it up here. I was asked by the NASA Administrator to create a vision for what a further morphing airplane might look like. So we had a good two days to prepare this for Congress, literally two days. This image was created.
The idea was could you use biological inspiration to create an airplane of the future? Wings that you could change the shape of. Sweep them back when you wanted to do high speed flight, but much more seamlessly. And then you might also embed whatís called flow control, to control the flow over the wings and have micro-tabs in the back, more like feathers versus todayís large control surfaces.
Again, the wings sweeping forward when you want to go slower, and then taking advantage of the biological inspiration -- split wing tips on turns, for example.
To be clear, this is a cartoon. A lot of folks write me and say how many people will fit on this airplane? When is it going to fly? Itís a cartoon that was designed for congressmen who canít spell airplane but need to understand what the future -- I hope none of them are in here, by the way. But it was designed as a cartoon to show how airplanes of the future might look.
What new steps have been taken in morphing and what have we learned so far?
In the Ď90s and the early part of this century there was a huge increase in adaptive technologies all over the world. Iíve been all over Europe and Japan on the same topic and all developing countries including India and China are putting millions of dollars into this particular field because if youíre able to do adaptation, it does change how cars drive, trains move, buildings are controlled.
I went to an earthquake engineering conference about three years ago and they were looking at using these smart materials in building that could literally control the vibration of buildings during an earthquake, for example.
Some lessons learned. Knowing when to morph. As I began this presentation I mentioned it doesnít always pay off. You have to know when to stick this new-fangled technology in.
The second one is understanding the mission assistance level requirements, and Iíll show you that in a minute. Shape change is not the goal. Thatís not what weíre trying to do. It is one good approach, but our approach has always been what does the airman need in this case, or what does the seaman need when you talk to the Navy? And letís figure out the right technologies.
Developing and modeling the approach. A lot of folks have asked me, do you use computer animations and are all the modeling tools there? No, they really arenít. We have some guesses. There are some parts we do well, other parts we donít do well at all. Frankly, very often with these new technologies we are building and testing. When we get in the laboratory we have an ďoh, crapĒ moment frankly, and say wow, we need to fix things, so we are still dealing with that.
It has to fly. A lot of folks say this is all about the hardware, but you guys fly airplanes for a living. You know. At the end of the day itís still got to fly. I get structural engineers that come to me and say Iíve got this new-fangled material. Our material scientists at NASA are great. Theyíve got their lab coats on. They come to me with this goo that can literally shake like the Terminator and change its shape in flight. They go, just slap it into the wing. I say, but it has to fly still at the end of the day. So getting aerodynamics in there; and also talking to pilots makes a big difference in how we apply this technology.
How do you cover it? One skin is not enough. We are researching a wide variety of flexible materials. In fact I just went to an Air Force workshop last week on flexible material for morphing aircraft that the Air Force AFRL in fact is funding as well as AFOSR, on flexible material systems for future aircraft.
How do you control it? Biology very often uses distributed systems. We tend to operate our things with one large computer controlling everything. Biology doesnít do that. The feathers in a bird are largely controlled individually. Theyíre linked together but each one can be manipulated different much like our fingers are. That same ideology is trying to be used to control future airplane systems. Again, we have some examples that I will show you.
So I mentioned that itís about the mission way up here, but the technology breaks down to the activators and sensors at the end of the day. A lot of research is going on here and then we do the testing and just build it up and build it up to full vehicles.
So Iíll show you some examples down here at the materials level, the mechanisms, and then actually some vehicles that are being looked at.
Design and testing. One size doesnít fit all. Keep that in mind.
Here are some examples of morphing wings but they are not for every system.
First of all, I mentioned weight is a big deal. Weíre very conscious of the fact that weíre not trying to make big, ugly systems that will never fit on an airplane. The first comment I get from a pilot is it weighs too much. I cannot fly that. Itís too complex.
This is one example of how we looked at weight. This is a chart of wing weight versus wing load. Basically how much the wing weighs versus how much it can carry. This is a historical average of over 52 airplanes. We are intentionally designing these systems to be in the weight efficient region. When we have a design that gets down here and itís too heavy, we throw it out, frankly.
So this is just one of the many studies that we do to keep us on track and not make a design unusable.
Here is a test of a seamless trailing edge. This was done in the year 2000 at the Transonic Dynamics Tunnel at NASA Langley, just three hours south of here. This was a UCAV model developed by Northrop Grumman. DARPA sponsored this program. The AFRL at Wright-Patterson was the monitor for this contract.
This is a trailing edge. What you will see is this wing going through a wide variety of changes. Instead of having an aileron and a flap, this wing has ten sections, ten little flaps, if youíll consider it, that are all connected by a rubbery-like material so there is no seam in this entire control surface. The only seam is here and here. Even at this point where it connects to the actual wing box, it is completely smooth. Again, the skin here is a flexible RTV-like material. This red on the end is just red tape to make it visually clear.
But they could basically create any shape they wanted to with the ten different surfaces, again getting more to how a bird would move, a variety of different control surfaces.
This wing was tested up to Mach .6 very successfully.
Another example. This is an example where all the control surfaces are not necessarily connected by a material. They are loose. Theyíre more like feathers.
The question that we pose to our controls guys is we would love to be able to control the lift distribution span wise on the wing. Can you actually do that if you break the control surface up into a bunch of little pieces? And can you get roll command control as well doing the same thing? The answer is yes. They actually, we thought weíd pose a really tough problem to them but they were showing off with this particular maneuver. They were very easily able to control the airplane, in fact better than you can do with a traditional aileron by having the distributed control surfaces on the airplane.
Another example of the fishbone concept that we looked at, it shows the analysis there. This is a thing we actually built, putting a skin on that is non-trivial, as you might imagine.
One more concept, an articulated thrust concept. Our space guys thought of this. Space structures or thrust structures are used very often in space. The same concept was used here. It required not only a flexible skin design in there, but there were also clamps. These are shape memory alloy clamps, another smart material thatís used, to lock the structure in place once you're done changing shape so that it would sit still when you wanted it to and be flexible when you wanted it to be. Again, itís one of biological analogy where that wing will twist on command and then it will lock solid into that one shape if you need it to.
Youíll notice these are called power off SMA clamps. That means when everything dies the thing will lock into place and not move.
An inflatable morphing concept. We had some concepts where we were looking at airplanes that became unstable suddenly, but you didnít want to carry the weight around of an extra aileron or an extra control surface the entire flight, so put your control surface in a canister, of course. When you need it, you blow up your control surface and bam, you have a wing on command. This inflatable wing, again, this was inspired by our space guys, weighed three pounds because it was inflatable. I was thinking three pounds, how can that possibly work? Itís payload capacity was 100 pounds. An extremely weight-efficient design, worked extremely well. This has been tested a number of times and we are hoping to try this on one of our flight projects.
Down here, by the way Iím not showing you all the data on these charts, but what I did want to show for those who are studying in some of these areas, we do do aerodynamic studies as well as structural studies on all of these concepts to understand their true performance capabilities and frankly, their issues as well.
So exploiting aero-elastic capabilities. Some of you are familiar with the active aero-elastic wing concept. In this particular case, and this is a flight test of it. This one also took 15 years from lab to flight. Let me explain how this concept works.
Right now, most of you are familiar with aileron reversal, of course. The ailerons basically get locked out or you donít use them at higher speeds because the wing twists too much to use them.
If you look at it from a controls perspective, the control of the airplane, the curve is linear through reversal. You can actually fly the airplane safely past aileron reversal. You can effectively put a negative sign in your control loft. However, pilots donít like to do that, right?
Some concepts that were used. The active flexible wing concept is, instead of trying to fight the flexibility of the wing and make the wing stiffer and therefore heavier to get around reversal, let the wing be flexible, fly past reversal, and give the pilots some capability in that ugly region where youíre going through the reversal speed. How you get the pilot the flexibility in the reversal period is having a leading edge control surface thatís also there.
So when you're going through the reversal dynamic pressure or velocity the leading edge kicks in to help you. At the end point your wing is actually very flexible, it actually does twist in flight, you are past reversal, but you have complete control over the airplane.
So in the end when this was flight tested on one of the airplanes at Dryden, on the F-18, the wing design was actually considerably lighter than todayís F-18 wing. So if you look at it from a systems perspective, I mentioned the cost of morphing. In this case we have a lighter wing because weíre allowing the wing to be flexible. Secondarily, the F-18 right now has a rolling tail. Thereís a lot of additional hardware in the tail to enable the airplane to roll. If you donít need that rolling tail the weight comes off. If youíre studying dynamics you know very well getting weight out of the tail adds to the stability of the airplane. So there are huge system benefits in this overall idea.
DARPA also had a program called morphing aircraft structures. Itís still in implementation. What they challenged the contractors to do was to envision large shape change in an airplane. And the mission that AFRL at Wright-Patterson came up with, who was leading this project, was a hunter/killer. An airplane that can hunt as well as kill. Very slow, high altitude, as well as high speed attack mode.
Two contractors were funded. Lockheed Martin as well as a company called NextGen. One of them, Lockheed had a folding design; the other one had more of an umbrella like design. Both companies, and Iím going to show you the Lockheed design in detail, thereís not time for both. Both companies did a lot of research on how to build this wing.
Lockheedís design, they had a knee joint here, two of them in fact, and they had to create actually a seamless skin to cover this joint. They did a lot of wind tunnel tests. Then they had to actually make this huge wing fold in. They worked on a wide variety of actuators.
They built this wing, a very large-sized wing you can see here. This is the open section where the actuators were.
This is both wind tunnel models. This is the Lockheed concept up here, this is the NextGen concept down here. These were both tested down at NASA Langley. This was a wing sweep concept.
The difference with this wing sweep concept by the NextGen Corporation was that instead of just being like an F-14 which basically is a wing roll kind of thing where the cord of the wing did not change. In this case they could actually stretch the wing cord as well and change the actual wing area while it was sweeping, so they had a huge change in the [wetted] area of the wing. Iíll show you a movie of that.
Lockheed had a folding concept to go from their attack mode to their loiter mode.
The movies are perhaps the easiest way to see it. Iíll try to get both of them going here.
If you look at this top one, the NextGen concept, you can see them shrinking their cord as well as sweeping the wings back.
Once again, this was at Mach .7. Both of these concepts will [plus it up] to Mach .9. Very successfully, by the way. There was no damage, no issues. We were actually shocked. We were preparing for a catastrophic failure and it worked very well.
The Lockheed concept, this folding wing concept. Again, the two knuckle joints here and here. This particular data came at Mach .6 but it worked very well. They even had a leading edge control surface right here that would fold in to tuck in and reduce the air flow between the wing and the fuselage. Both concepts worked extremely well. These were tested just last fall. I think this is the first public presentation of this data, in fact.
So the next phase of this program was to go to flight. Basically that phase of the program was to say could you design it, could you build it, and the answer there was yes, of course. It was hard, donít get me wrong. We were crossing our fingers through every second of that test.
The next phase is to fly. Can you control an airplane whose shape is changing that dramatically? Right now we are working with DARPA to do this flight test program. The same two contractors. In this case theyíre flying RPV concepts. Both flight tests should take place next spring, so hopefully, if Iím back next fall, weíll have great data on if these flew and how well they flew.
Morphing without shape change. I made this big lecture about how morphing is not shape change, of course. What else could it be?
Thereís a concept called micro-flow control thatís been studied now for probably the last eight or ten years now. The idea is youíre using pulse control, very small inputs to the flow for global flow control. You take a very small jet, the size of your fist. You embed it inside an air foil. That very small jet creates a plume of fluid right above, itís air, right above the surface of the air foil. In doing so you basically circulate the flow. Therefore if you do it just right and at the right locations you can actually control the flow. You can go from this to this without moving anything by simply manipulating the flow.
It sounds like science fiction. Hereís a picture of this exact same concept. In this particular movie thereís one of these little jets right back here, you see it spinning out. By basically blowing air straight out it forces the flow in a certain direction. We can put a sine wave pulse into it. We can point it downward. But basically we can make the flow go where we want it to by using a very, very small input to the flow.
How does this work, a lot of folks say? To give you some other ideas, feathers are exactly the same thing on a bird. Theyíre very very small. They arenít like a big flap or an aileron, but enough feathers and you can control the whole bird, if you will. This concept is not any different.
Letís look at some more examples of this. Some capabilities of this idea called micro-flow control. Thrust vectoring. All of you are familiar with thrust vectoring veins on the back of an airplane. What if you didnít have to have the veins? What if you could use flow control, as Iím talking about, to get the same effectiveness? So you donít impact the engine performance, it helps you with LO, and you actually have better performance overall and also less weight in the back end. Weíve not only done studies computationally, as is shown here, but also in our laboratory with excellent results.
Another example, this is called power lift using pulse circulation control, and the airmen in this room will know, getting off the ground quickly is non-trivial. How weíve done it historically is using something like powered lift. Very energy hogging concept. What if you can get more out of the wing itself by simply vectoring the flow around the wing? This again has been shown.
This is what these jets look like. Very tiny. These circles, about the size of your fist. Again, you embed them in the wing.
The idea, again, is to simplify things. Instead of having all this clap trap in the back end of your high/low system you can embed these things and go to a much smoother design.
There is real data on this concept. This is not just a pie in the sky idea. Thirty to 50 percent drag reduction. Again, not a small number. And 20 to 70 percent lift increase. Huge numbers. They really are. Itís actually surprising.
Some more data. This data, by the way, was taken five years ago. We actually have better stuff but this is the simplest one to show in a form like this. This is what it looks like with the control off, with the control on.
In this case we have jets right back here, right near the hinge point at the control surface.
Again, the idea is to go from this concept to a much smoother concept by putting jets just where you need it at the separation points. A much smoother concept.
This is the actual data from the test. This is the coefficient of lift, or basically lift versus a deflection of the control surface. Again, very large numbers, very repeatable capabilities.
Another concept. What was interesting about this particular idea, we took a UAV concept, thereís a picture of it in the wind tunnel. We put these jets all on the leading edge. Our challenge here was okay, lock the control surfaces out. Donít use any flaps, donít use any ailerons, can you maneuver the airplane with just these little teeny jets embedded in the leading edge?
The answer is yes. It was scary, Iíll be honest with you. This picture, there was no way for us really to show this entire beast moving in the wind tunnel and get the cameras around it. This picture shows you, you can see the effectiveness of the jets on a traditional control surface.
What I will show you is over here, this is again lift versus angle of attack. We could reduce the lift or we could increase the lift using these jets. You might ask, why would you ever want to reduce lift on an airplane? Yaw control, roll.
We had amazing control over this bird without using control surfaces at all.
Now would we actually want to fly it this way? Probably not all the time, frankly. Ailerons work extremely well and are better, frankly, at some points in the flight regime. So where we are now with this study is understanding -- Youíll notice here the big benefits came past 15 degrees angle of attack. The reason is that at this point flow is so separated. This is where your ailerons fall apart. They have no more flow on them, they canít get you any more effectiveness. You turn these guys on, they give you back the aileron performance that you want.
So perhaps in an actual mission how you would use this is you would use your traditional ailerons up to the point where the flow started to get ugly on the aileron. You would turn these guys on and bam, youíre back to the original performance you had but at higher angles of attack.
Hereís actually some flight test data. I think this was 2001. XV-15 tilt rotor. A very short flight test, but the idea was jets were put on these horizontal surfaces right here. Obviously down-wash is a big deal. This is with the flow control off, what it looked like. Of course these big rotors are pouring down air on these control surfaces. You put this flow control on. You can see the flow is greatly cleaned up around this horizontal surface right there. Thereís a lot of data on this, and again I wonít go over all of those, but I just want to show you that this has been flight tested and there are other flight tests that are coming on as we speak.
Iím going to close with morphing with the aliens. I promised to show you a planetary explorer from morphing other flight regimes.
Going to Mars. One of our challenges. First, you have to get there. Youíre only going to get there in a capsule which is a problem if you plan on flying. So we would have an airplane in the capsule. Basically the airplane would drop, the wings would come out, and then it would actually fold back out from the fuselage and fly. This is how you would actually fly on Mars. It turns out itís much easier to do surveillance of Mars from the air than it is from the Rovers that weíre all very familiar with.
That sounds easy. What about in practice? We took a balloon up to 100,000 feet, actually beyond that, and released an airplane on our planet to do exactly the same thing. Weíre looking up to the balloon. There is the airplane. This is the earth, by the way. Itís completely unstable right now, itís falling madly. The wings pop out and you can see the control surfaces working like mad. Itís complete free-fall. It has no control at this point whatsoever. Then it gets control. Now it picks the nose up. Youíll see itís still at probably 90,000 feet. Youíll see the curvature of the earth right there.
This thing came down to a perfect, beautiful landing from a 100,000 foot drop, and unfolded or morphed beautifully on command. This is the concept we hope to put on Mars in the next ten years.
So how do you fit the baby in a small package? Hereís your airplane. The first thing you do is flip the baby over. You fold its legs in one at a time. Then you tuck the bottom in. A little bit more of a twist. Then you put the cap on it. Thatís how we actually fit it into the capsule that would go to space.
Some concluding remarks.
Morphing airplane concepts has continued to evolve. A lot of folks tell me, well, airplanes are a pretty mature technology. We fly today. The answer is yes, of course they do. I wouldnít be in this field if I didnít think so. However, I would challenge folks and say they are not done. They are not complete with the kind of things we can do. Our plan is to make the next century of flight even more exciting than the first century of flight, and with the kind of technologies that are coming on board, we firmly believe that is entirely possible.
Morphing for the mission. We really do start with the vehicle requirements. I get a lot of folks that tell me can you just take this one idea and slap it on this one airplane? Again, weíre not going there. It has historically proven to be unsuccessful.
Knowing when to do it. It doesnít always pay off. Again, these technologies are great, but weíre trying to put them on where it makes sense.
Knowing how to do this. Trying to get the computer, the structure and the aerodynamics and the pilot to all talk the same language is a fascinating challenge, as you might imagine.
It has to fly. We are blending these technologies of having basically a bionic wing that now has to talk to your flight control system. Both of those are not yet coming together. Weíre trying, but integrating it is still a huge challenge.
Materials are still the key to many of these things. These ďbionicĒ technologies. Mostly inspired by materials. Weíre able to physically morph the wing. Even those little jets would enable a tiny jet that small to create those flight tests I just showed you, is a small diaphragm thatís an active material. If we had to use a tiny motor it would never have worked, because we tried, by the way.
Nature still has a lot going on. We have found some fascinating things when weíve stopped to actually study nature. Iíll give you one example. We looked at sharks. Their skin is actually very rough. Why a shark? A shark never sleeps. The thing always moves, itís in constant motion. What makes the thing so efficient? It doesnít actually have smooth skin like we have on airplanes and boats, it has very rough skin. So the riblet concept is the same idea. Weíve learned actually that by making the skin on an airplane strategically rough, you can actually reduce drag, believe it or not. But as with every concept, it only reduces drag at a certain part in your flight regime so you want the roughness to go away when you donít need it any longer. So we are looking at variable roughness skin concepts for airplanes that actually work extraordinarily well.
A few more. Technology challenges. Working with these unconventional technologies and figuring out how to use them is a huge challenge. Retrofits really dramatically under-use the technology.
We spent some time historically looking at how new technologies come on board. You know, weíre dumb as dirt. Engineers, scientists, we do not apply new technologies well. The first metal airplanes, after we went from wood to metal, if you remember, wood in the airplanes had solid wood wings, right? So metals came on line. Great, letís apply metals. We made solid metal wings at first because thatís what we knew to do. Dumb as dirt, we now know that of course.
So what we are telling ourselves is we know darn well we are not using these technologies the best that we can, and weíre learning every single year. Every year we have an aha, that creates a capability we didnít have before.
Risk in learning. Our part of the [fun] in success -- test early, test often; fail early, fail often; and you will have success.
The performance demands on airplanes are continuing to increase. Weíre asking more of the airplane. In my humble opinion, bring it on. Thatís what the technology is there for. So we are pushing the envelope and that is exactly our intention.
I left about nine minutes for questions.
Ms. McGowan: That is correct. The internal of the wing would look entirely different depending on the way weíre using it.
If you look back at one of the concepts I showed earlier for the Lockheed and the NextGen concepts. These two wing designs. This one obviously is clear, the skin was basically clear, it was an RTV material. The inside of the wing looked like an umbrella structure versus a traditional [monacoctric] like weíre used to. Lockheed had a much more traditional design. Within this inner panel here it looked like a traditional airplane wing. It was just these joints where things got very interesting in a hurry. So this is again, just one idea. There are many more that are out there. So yes, it does depend.
Even the area of hydraulics. Right now we run massive tubes of hydraulics all over the airplane wing and the main reservoir typically sits near the wing root or something like that. Itís a messy, complicated system. What if you could have the reservoir sit very near the ring in a very small package? The problem is you have to be able to pump it efficiently to move the control surface. Again, this is where the new materials come in. These materials are very small but theyíre very powerful. You can create a micro-pump that can actually pump the hydraulic fluid very effectively. Several companies have actually looked at and are under development of looking at Iíll call it local hydraulic pumps. So the pump sits right at the edge of your flap or your aileron. So no longer do you have huge pipes running all over the wing. So itís even changing that part of how we would look at designing an airplane wing.
Question: [Inaudible] the atmosphere on Mars [inaudible]?
Ms. McGowan: It changes everything. Every last thing we learned in school gets thrown out the window. We actually call the Mars airplane a transonic butterfly, basically. Thereís no atmosphere, or very little atmosphere, so basically itís a butterfly. It has to be very very easy to work with. It canít be heavy at all. But at the same time its atmosphere is completely different.
So yes, we basically had to throw out everything we knew about airplanes and work in a regime -- Itís not a scaled down, large airplane at all. Itís flying at a Reynolds number and an altitude that we donít even think about using airplanes. Itís like flying an RPV at 60,000 feet. You donít do that here on this planet.
So yes, we had to start from ground zero.
As far as the materials that are used in it, the Mars airplane, this particular one, we used very conventional material. We did not use any smart materials whatsoever. We tried to take off-the-shelf mechanisms, frankly, so that our space counterparts would not be worried about a new technology. What we focused on was ruggedizing the deployable mechanisms so they would snap every time repeatedly.
In fact Lockheed in their design for this folding wing, same idea. They used F-16 actuators to fold this wing. They did not want to create a new one.
NextGen created something brand new, obviously, in their particular concept.
Ms. McGowan: Yes. What you're asking about is taking the materialís natural frequency and using it to control the air flow? Yes. In fact those pulse jets that I showed you that you can embed inside the wing? We have found there are certain frequencies you want to use for Mach .1 and certain frequencies you use for Mach .6. We thought it would be a function of force only. Of course humans, we want big, bad force. We were just driving those puppies as fast as we could when we went to a higher speed. It turns out itís not a forcing thing. Just like feathers. It wasnít about force, it was about frequency and also about the type of oscillations. This is going to sound nuts, but at Iíll say Mach .6 for example, a square wave being put into those little pulse jets had a much greater effect than a sine wave did. Very very little input.
So yes, frequency matters. Itís not something that is intuitive to us, but itís very common in nature.
Ms. McGowan: Thereís always one in every group that asks. Yes. Plasma actuation. Many of you are probably familiar with it in terms of heating something up. How plasma could be used aerodynamically as opposed to just for heating something. When the air is flowing over a wing itís going to stick. The air thatís touching the wing will actually stick to the wing. Of course creating drag. In fact what you really want is the air to be slippery on the surface of the wing. What the plasma effectively does is it creates a slick condition. Historically what you were taught in aerodynamics is called a no-slip condition. It sticks. Turn the plasma on, the wing becomes like glass and the air slips right by it, changing drag completely. Therefore you can actually turn it on, turn it off when you want, roll the airplane, control the airplane.
It is similar to one of those flow control concepts I showed you earlier, you can turn things on and off.
So the answer to your original question, yes. We have looked at it. Itís a very power-hungry concept, is the deal. We had what I call our friendly mad scientist, he looked like a mad scientist, too, in a lab working on this. When I went over to see this behemoth, he showed me, he lit a little cigarette and put it on there. Poof, the little flow went right away. It was quite amazing. So dramatic capability.
But I asked our mad scientist, how are you powering this thing? There was this massive, like World War II system behind him that powered this little teeny thing.
So right now the big complicating factor is power. Can you reduce the power? And when we actually talked to people that do power for a living and computational folks, their comment is in ten years it wonít be an issue, if not less. So itís not an aerodynamic challenge, itís really in that case a power challenge. And of course you canít fly something that large, itís volume and power. But again, our power guys say given how power technology -- look at your cell phone. How in ten years it went from the huge bag phones to this. Theyíre saying if that trend stays weíll have licked that problem within the decade.
Good question. A very very powerful technology. Scary powerful, actually. Very scary. Nothingís moving. Thereís nothing shaking, wiggling, pumping at all, and your airplaneís being controlled. Pretty scary.
Ms. McGowan: Good question. Basically these little jets, basically what theyíre doing, thereís a little teeny cavity under the surface of the wing. This is the surface of the wing. Thereís a little cavity under the wing. A very tiny cavity, the size of your fist. Inside this cavity is a little membrane thatís this smart material, and what itís doing is itís sucking the air in and spitting it out very rapidly. Itís sucking in and spitting out. A lot of folks have asked me, wonít these things clog? No. If a bug comes in, a bug gets spit back out. Not in great form, but it gets spit back out again.
Whatís interesting about this, the idea of using blowing and sucking is not new either. If you go back historically, there were tests using blowing and sucking back in the late Ď70s and early Ď80s. However, how they had to do it back then is they had to draw from the engine to suck it in or blow it out. There were huge tubes running through the airplane. Clogging those things was a huge issue. Whatís very different today is that thatís an enclosed chamber. Thereís nothing going through that thing but a little teeny volt of electricity to power the little membrane. Itís a little membrane that beats, like as it sucks and spits it right back out again. Also, redundancy. Again, nature, studying biology has taught us nature does things in a redundant fashion. Instead of having four wheel drive theyíre going to have million wheel drive in tiny, tiny things. So if one thing goes out, it can still be controlled.
So you would take these little jets, again, very small, self-contained, no clogging issues, spread them out on your wing, and then if one or two of them cause you an issue youíre still doing great as far as flying goes. Thatís basically how they work. And theyíre mixing the high momentum air flow with the low momentum air flow in the boundary layer and thatís how they create this control basically.
This small jet, unbelievable, combined with other factors has a very very powerful effect.
# # # #
Return to AFA Air & Space Conference Page