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Changeable wing shapes and surfaces

Old 09-25-2012, 04:53 PM
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Default Changeable wing shapes and surfaces

I've seen a number of ideas put into test stage on morphing wings, from boundary layer control to airfoil alteration. It's highly desirable from an aerodynamic point of view. However, it adds weight and taxes the structural elements, even if you have the technology to do it. Morphing wings are a problem the next generation of engineers will possibly bring to maturity.
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Morphing’ Wing Under Development


(M. Phelps, Flying, 9/25) German research company DLR completed wind tunnel tests early this month on a unique new concept in wing-leading-edge design. Rather than slats, the new-concept wing has a leading edge that changes shape internally, “drooping” to a higher-lift airfoil configuration without the drag and noise of leading edge slats.
The design uses a flexible glass-fiber reinforced material shaped by internal actuators and movable support structure. “The leading edge can be lowered by up to 20 degrees with virtually no loss of lift,” said project leader Markus Kintscher of DLR’s Institute of Composite Structures and Adaptive Systems in Braunschweig, Germany.
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Old 09-25-2012, 06:32 PM
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NASA is also doing research in this area:

NASA - NASA's Twist-wing Jet Explores A Radical Future
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Old 09-26-2012, 07:40 AM
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Yep that's there, and when I was in school some grads were doing research on porous wing skins that pump air through for boundary layer control using very small holes. It made a huge difference in the flow adhesion at high angles of attack, allowing a lower drag in cruise. As usual, we are never short on ideas like this because they spring naturally from fundamentals, it's more that we are short on R&D investment. This is an area that will offer serious improvements in aircraft design in the next few decades. The 787 for example has high deflection composite wings that bend a lot to smooth out the ride. That's a comfort application, but changing wing shapes can greatly increase fuel efficiency and cruising range.
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Old 09-26-2012, 10:25 AM
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Default Been there...

Cub:

Unless you went to school in the early 1960s, it has been done before....

Northrop X-21 - Wikipedia, the free encyclopedia

(it didn't work out so well; those vacuum-cleaner holes tended to plug with dust, bugs, rain, or anything else).
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Old 09-26-2012, 11:00 AM
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There are other ways to do it, I forget how that one worked. Actually I never knew, just that they were working on it.

My senior project was to design a military cargo transport with boundary layer control using circulation control technology (see link), which was basically just a tube supplying bleed air to re-energize the flow at back of the wing and prevent separation at low speeds. CCW is a proven technology that can really shorten field distances. My conclusion was there was no great reason not to use it other than high R&D cost and fear it might fail at the wrong time, so I expect CCW to appear in airliners eventually. It is a simple system that replaces all mechanical flaps and slats. If it had been around when the early airliners were developed it would be in use now.

wiki on CCW

The Boeing C-17 uses jet wash against the flaps in a blown flap arrangement, same thing but much simpler-

wiki on blown flaps
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Old 09-26-2012, 05:33 PM
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I see some great advancements in this area in the next few years. We've seen triple slotted flaps go back to single for simplicity, but looking at a wing, there have to be some new radical ways to improve lift at low speed by making it bigger or make the air "stick" better, whilst still giving good cruise. The wing warping is just one, but hopefully there'll be some new takes on the whole thing soon.
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Old 10-06-2012, 07:33 AM
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Another nice article on this. Looks like the students need to work on their RC flying skills bit more though (see video).

~~~~~~~~~~~~~~~~~~~~~~~~~

Aircraft designers crafting more bird-like wings

(J. Moore, AOPA Online, 10/05/12) A leading edge that can change its shape was tested in August and September in Russia. Photo courtesy German Aerospace Center (DLR). Turns out, those bicycle mechanics from Ohio were on to something with those warping wings of theirs. The invention of ailerons and flaps relegated warping wings to the sidelines, but a growing number of aeronautical engineers are turning back to that page and developing wings that are more distinctly bird-like, able to change their shape to best suit a given phase of flight, or offer more precise control. The various approaches hold promise to produce future aircraft that are more nimble, efficient, and quiet. There’s a chance that pilots of the future may not even know what an aileron is without cracking open a history book, or a flap, for that matter. Leading edge slat? What’s that? The slats, which are needed on heavy airliners to boost lift at low speeds, are the target of a European collaboration—the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR), is working with Airbus, EADS Innovation Works, and Cassidian Air Systems. Wind tunnel tests conducted in August and September in Russia showed promise for another strategy: change the shape of the leading edge using piston actuators inside that change the shape of a composite leading edge. The design still needs to be refined to handle icing, lightning, and bird strikes, but the initial results show promise: a 12 percent reduction in drag, and a noise reduction, achieved by eliminating the gaps between control surface and wing. Another approach to warping wings was demonstrated in 2010, with successful test flight of a radio controlled model airplane controlled with similarly seamless surfaces. Demonstrated in a YouTube video, the concept model responds to control inputs with curling deflections of portions of the wing, and horizontal and vertical stabilizers that correspond to where standard control surfaces would be placed. Instead of actuators or servos, the lightweight design uses a small microchip to coordinate electrical current, energizing and de-energizing strips of macro fiber composite (MFC) materials—a NASA invention from 2000 now licensed to private manufacturers. The wings and stabilizers are filled with MFCs, able to twist and deflect, driven by materials that act more like muscle than machine...

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Old 10-06-2012, 08:38 AM
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Here's an expert demonstrating wing shape-changing:

YouTube - Broadcast Yourself.
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Old 10-06-2012, 08:42 AM
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Very nice, Tom. Here's a embedded link to the video. Reverse thrust with camber increase...

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Old 11-22-2012, 06:25 AM
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Nice article about seagull aerodynamics.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The Magic of Flight: Your Airplane is a Close Relative to the Seagull

(D. Pimentel, Airplanista) ...From the first few days when humans watched birds fly, we have been in awe of their beauty and functionality. With effortless ease, they take a few steps, flap their mighty wings, and launch skyward in a full STOL takeoff that would make a Maule seem like a DC-10 cargo ship trying to plunder its way into the sky. I spent a weekend in 2007 over on the Oregon coast at Lincoln City, which at the time was getting pounded with gusts to 60 mph on its way to a walloping with winds as high as 129 mph at Bay City. But while the wind was blowing, I came across a huge parking lot full of seagulls that were having a ball in those gusts: one by one, the gulls would just flap their wings, propelling them up gracefully into the wind. At about three feet over my head, they would just hover, not flapping their wings, but letting the wind provide all the lift they needed to stay basically in one place. After that gull was done with his/her kite imitation, another would launch up into the gusts coming off the beach and play the hover game.

I had my newest camera with me, a Canon 40D, with a 200mm prime Canon "L" lens out front. With the drive set to max of about six frames per second, and the autofocus set to continuous (a sports mode), I was able to run all over the lot, chasing hovering seagulls. About 458 images later, I came back to my hotel and discovered some amazing things about birds. These mega-closeups of gulls in hover mode showed me the anatomy of a bird like I had never seen. If you refer to the photo at the top of this post, you will see the following five things:

1. The trailing edge of the gull's wing stretches out substantially to form a very large "flap" which provides additional lift for slow flight. This was confirmed on other shots of the gulls in fast flight, when these "flap" feathers were retracted.

2. Complementing the "flaps" are what appear to be leading edge slats on the wings. When you study the complete design of this gull's wing, it resembles a jetliner's wing in its "dirty" landing configuration. I find the gull's wings to be stunning works of art.

3. In slow flight, the gulls would flare their tail feathers wide, to create a sort of "horizontal stabilizer" to give the southbound end of the northbound bird extra lift. In close with my telephoto lens, I was amazed watching them steer by flexing these aft feathers ever so slightly, just enough to keep their beak aimed directly into the wind.

4. In hovering mode, the gulls would drop their retractable "gear" to help steer and stabilize their fuselage. As the gusts increased, the "gear" would come down to dirty up their airframe...and when the speed of the gusts dropped, the gull would retract their feet to clean up and eliminate any excess drag. Amazing.

5. The gulls kept their aerodynamic beak aimed PRECISELY into the wind. They would hint at their next movement ever so slightly when they would aim that beak left or right just before peeling off in either direction to pull out of the hover.

After a few seconds of hovering, each gull would crank into a hard left or right one-eighty, suck in their flaps and spoilers, yank up those retractable feet, and blast off downwind, picking up speed like they were shot from a cannon. All the time, I imagine they were smiling. When you really look at birds up close in stop-action, they do have many similarities to the flying machines we fly. They have wings, we have wings. They have a tail, we have a tail. They have natural navigation instincts, we have GPS. They are free as the wind, we must adhere to strict FAA policy and follow ATC's instructions. Two machines to accomplish the same feat...flight. One is designed by teams of aerospace engineers and costs thousands, even millions of dollars. The other, comes out of an egg...
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