Changeable wing shapes and surfaces
11-22-2012, 05:57 PM
#11
Moderate Moderator
Joined APC: Mar 2008
Position: Curator at Static Display
Posts: 5,681
AFTI F-111 Mission Adaptive Wing
Cub:
Thought of this the other day. The Air Force tested an F-111 with a "bendable" leading and trailing edge back in the early 90s as I recall (Wiki didn't have an article [just the picture] and I couldn't find any dates). The link below is the only data I could find on a quick look.
By having a variable sweep and variable chord shape, it was the most "variable geometry/planform" ever flown.
So, there may be a resurgence, but the concept is at least two decades old. As an Mech Engineer, I would guess the biggest complications are fatigue/reliability of flexible wing skins, while keeping them light enough to be practical.
http://en.wikipedia.org/wiki/File:Ai...FTI_NASA_0.jpg
Thought of this the other day. The Air Force tested an F-111 with a "bendable" leading and trailing edge back in the early 90s as I recall (Wiki didn't have an article [just the picture] and I couldn't find any dates). The link below is the only data I could find on a quick look.
By having a variable sweep and variable chord shape, it was the most "variable geometry/planform" ever flown.
So, there may be a resurgence, but the concept is at least two decades old. As an Mech Engineer, I would guess the biggest complications are fatigue/reliability of flexible wing skins, while keeping them light enough to be practical.
http://en.wikipedia.org/wiki/File:Ai...FTI_NASA_0.jpg
11-23-2012, 09:09 AM
#12
Moderator
Thread Starter
Joined APC: May 2006
Position: ATP, CFI etc.
Posts: 6,056
Interesting.
It is common in the engineering sciences for advanced theoretical ideas to greatly presage their practical implementation, and ideas for highly changeable wing shapes are such an advance waiting for the right time. It is interesting to note the bulk of aeronautical advances we enjoy now actually spring from the hurly-burly days of WWII, little items we take for granted like supersonic airfoils, turbine powerplants, inertial navigation, and airborne radar. Not sure what it will take to get changing wings and other known advances into production but anything worthwhile is generally adopted by a forward- looking company when the time is right. Since war is the strongest motivator, maybe it is a good thing we are a bit behind on changeable wings. One thing that should help is the advent of very small and sophisticated stability computers, such as we see on the current crop of UAV helicopters and multi-copters.
It is common in the engineering sciences for advanced theoretical ideas to greatly presage their practical implementation, and ideas for highly changeable wing shapes are such an advance waiting for the right time. It is interesting to note the bulk of aeronautical advances we enjoy now actually spring from the hurly-burly days of WWII, little items we take for granted like supersonic airfoils, turbine powerplants, inertial navigation, and airborne radar. Not sure what it will take to get changing wings and other known advances into production but anything worthwhile is generally adopted by a forward- looking company when the time is right. Since war is the strongest motivator, maybe it is a good thing we are a bit behind on changeable wings. One thing that should help is the advent of very small and sophisticated stability computers, such as we see on the current crop of UAV helicopters and multi-copters.
11-23-2012, 09:36 AM
#13
Moderate Moderator
Joined APC: Mar 2008
Position: Curator at Static Display
Posts: 5,681
Went to NASA's site after I posted this. Found out it was actually 1983-86 time-frame, not the 90s, so the concept is 30 years old+. The site doesn't have much else, though....no results, or even where it went when they were done with it (they have histories on many of the others, such as the F-8 re-winged with a supercritical airfoil).
Many intriguing ideas have come and gone. Some concepts, while great from an aerodynamic perspective, were proven impractical when manufacturing cost, reliability, and maintenance are included. Variable wing-sweep is a classic illustration: all the rage in the 60s and 70s; now no one is doing it. I've been told that the winglets on the 747-400 save gas, but the increased maintenance they cause equals or exceeds the cost of the fuel savings!!
I suspect these types of high-lift devices are slightly better from a L/D perspective....but not by much. As such, I think their cost still outweighs their benefits.
"Forward thinking" companies are generally not seeking to be gregarious benefactors of aeronautical mankind. They innovate when they can make money from it. Bendable skins for "smart" leading and trailing edges will become commonplace when it is cheaper to have them on an airliner than when it is not.
And some company will be there, outsourcing the engineering to India, and the manufacturing to China, to make them.
Many intriguing ideas have come and gone. Some concepts, while great from an aerodynamic perspective, were proven impractical when manufacturing cost, reliability, and maintenance are included. Variable wing-sweep is a classic illustration: all the rage in the 60s and 70s; now no one is doing it. I've been told that the winglets on the 747-400 save gas, but the increased maintenance they cause equals or exceeds the cost of the fuel savings!!
I suspect these types of high-lift devices are slightly better from a L/D perspective....but not by much. As such, I think their cost still outweighs their benefits.
"Forward thinking" companies are generally not seeking to be gregarious benefactors of aeronautical mankind. They innovate when they can make money from it. Bendable skins for "smart" leading and trailing edges will become commonplace when it is cheaper to have them on an airliner than when it is not.
And some company will be there, outsourcing the engineering to India, and the manufacturing to China, to make them.
12-09-2012, 12:49 PM
#14
Moderator
Thread Starter
Joined APC: May 2006
Position: ATP, CFI etc.
Posts: 6,056
Check this out- these people seem to know a few things about changeable wing shapes. The engineering side of me would love to work for a company doing stuff like this. I doubt we will see any of it adapted to commercial aviation, though.
07-25-2013, 07:43 AM
#15
Moderator
Thread Starter
Joined APC: May 2006
Position: ATP, CFI etc.
Posts: 6,056
CCW for airliners
Some research is going on for the precise thing I was into in college, which is this circulation control wing technology (CCW). CCW is very good at pushing up lift curves without adding a lot of extra high lift devices. Robert Englar was the major champion, one of my old professors.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~
The Future Of Flight: A Congestion-Killing Aircraft [STOL]
(D. Coburn, 7/24/13, Popular Science) "Meet the 100-passenger plane that'll keep your flight running on time." Aircraft design is often overlooked in discussions of the FAA’s multibillion-dollar NextGen initiative, the elaborate mélange of satellite-based guidance, arrival, and departure technologies intended to modernize the outdated and much-criticized national airspace system by 2025. Yet a team led by researchers at California Polytechnic State University found that one of the easiest ways to improve system efficiency may be to reengineer the plane itself.
As part of a five-year NASA research project, the team designed a 100-passenger Cruise Efficient, Short Take-Off and Landing (Cestol) airliner that could arrive and depart at steep angles to and from 3,000-foot-long runways. “This plane was designed with a circulation-control wing, which generates higher lift at lower speeds,” says David Marshall, an associate professor with Cal Poly’s aerospace-engineering department. “We can reduce the field length by 50 percent.”
For the past year, scientists have wind-tunnel-tested a 2,500-pound model with a 10-foot wingspan, nicknamed Amelia (for Advanced Model for Extreme Lift and Improved Aeroacoustics), at NASA’s Ames Research Center.
Other researchers studied how Cestol planes would integrate into existing infrastructure. Results show that in tandem with NextGen’s approach and departure routing, which could allow planes to fly outside traditional flight paths, Cestol aircraft could land at underused, shorter runways or at smaller regional airports. Spreading air traffic over more runways would relieve congestion and substantially reduce flight delays.
Because aircraft-design cycles can span decades, Cestol craft will probably not arrive on commercial runways for a dozen years or more. But when they do, Amelia will probably stand as an influence. “I don’t know that Boeing will make a plane that looks just like Amelia,” Marshall says, “But I do expect some of the technology to transition over.”
How It Works: The Cestol Airliner
Over-the-Wing Engines: Scientists at Cal Poly mounted the Cestol’s turboprop engines above the wing—as opposed to underneath it—for two reasons. First, exhaust passing over the wing increases lift. Second, the wing deflects engine noise, shielding communities below. “NASA wants aircraft noise reduced by 52 decibels,” Marshall says. “So far, we’re already looking at a 30-decibel reduction.”
Circulation Control [Wings]: Conventional wings often have multiple flap elements, which rotate downward to increase the curve of the airfoil. The Cestol has a single flap, augmented by a narrow slot that runs the length of the wing. When the flap rotates downward, the slot channels high-pressure air over the top of the wing and directs the wind stream downward, increasing lift.
Deflecting Jet Exhaust: To combine the effects of engine exhaust and circulation control, the team moved the turbofans to the front of the wings. When the flaps rotate down, the exhaust is pulled into a low pressure region, which increases lift and allows for even slower and steeper ascents. “With this design, we can generate lifts five to 10 times higher than a conventional wing,” Marshall says.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~
The Future Of Flight: A Congestion-Killing Aircraft [STOL]
(D. Coburn, 7/24/13, Popular Science) "Meet the 100-passenger plane that'll keep your flight running on time." Aircraft design is often overlooked in discussions of the FAA’s multibillion-dollar NextGen initiative, the elaborate mélange of satellite-based guidance, arrival, and departure technologies intended to modernize the outdated and much-criticized national airspace system by 2025. Yet a team led by researchers at California Polytechnic State University found that one of the easiest ways to improve system efficiency may be to reengineer the plane itself.
As part of a five-year NASA research project, the team designed a 100-passenger Cruise Efficient, Short Take-Off and Landing (Cestol) airliner that could arrive and depart at steep angles to and from 3,000-foot-long runways. “This plane was designed with a circulation-control wing, which generates higher lift at lower speeds,” says David Marshall, an associate professor with Cal Poly’s aerospace-engineering department. “We can reduce the field length by 50 percent.”
For the past year, scientists have wind-tunnel-tested a 2,500-pound model with a 10-foot wingspan, nicknamed Amelia (for Advanced Model for Extreme Lift and Improved Aeroacoustics), at NASA’s Ames Research Center.
Other researchers studied how Cestol planes would integrate into existing infrastructure. Results show that in tandem with NextGen’s approach and departure routing, which could allow planes to fly outside traditional flight paths, Cestol aircraft could land at underused, shorter runways or at smaller regional airports. Spreading air traffic over more runways would relieve congestion and substantially reduce flight delays.
Because aircraft-design cycles can span decades, Cestol craft will probably not arrive on commercial runways for a dozen years or more. But when they do, Amelia will probably stand as an influence. “I don’t know that Boeing will make a plane that looks just like Amelia,” Marshall says, “But I do expect some of the technology to transition over.”
How It Works: The Cestol Airliner
Over-the-Wing Engines: Scientists at Cal Poly mounted the Cestol’s turboprop engines above the wing—as opposed to underneath it—for two reasons. First, exhaust passing over the wing increases lift. Second, the wing deflects engine noise, shielding communities below. “NASA wants aircraft noise reduced by 52 decibels,” Marshall says. “So far, we’re already looking at a 30-decibel reduction.”
Circulation Control [Wings]: Conventional wings often have multiple flap elements, which rotate downward to increase the curve of the airfoil. The Cestol has a single flap, augmented by a narrow slot that runs the length of the wing. When the flap rotates downward, the slot channels high-pressure air over the top of the wing and directs the wind stream downward, increasing lift.
Deflecting Jet Exhaust: To combine the effects of engine exhaust and circulation control, the team moved the turbofans to the front of the wings. When the flaps rotate down, the exhaust is pulled into a low pressure region, which increases lift and allows for even slower and steeper ascents. “With this design, we can generate lifts five to 10 times higher than a conventional wing,” Marshall says.
