"Flying wing" designs that offer reduced weight and drag when compared to traditional "tube with wings and a tail" designs are theoretically the most efficient aircraft configuration. However, true flying wings are inherently unstable and difficult to control. To aid in the design of future aircraft that utilize such a design, researchers at the German Aerospace Center (DLR) have been performing tests to study the flight characteristics of large flying wing configurations using what has been dubbed a flying "chameleon". The DLR's Advanced Technologies Testing Aircraft System (ATTAS) research aircraft resembles a conventional small passenger aircraft, but it has been fitted with special hardware and software to give it the flight characteristics and performance of an entirely different aircraft.
In addition to conventional mechanical flight controls, ATTAS is also equipped with an electrical flight system that allows the researchers to alter the aircraft's flight characteristics. As well as being able to simulate conventional airplanes, ATTAS is also capable of simulating entirely different aircraft designs. Although ATTAS consists of a cylindrical fuselage with wings and a tail unit, the DKR researchers have been using the craft to carry out flight tests that simulate a flying wing model developed as part of the EU project NACRE (New Aircraft Concepts Research).
"With its special control technology, ATTAS can behave like other aircraft while in the air," explains Dirk Leibling, a researcher at the DLR Institute of Flight Systems. "This gives us the opportunity to simulate aircraft that do not even exist yet, and to see where we still need to make improvements."
The simulated aircraft consists of a triangular fuselage with two vertical stabilizers at the tail that are tilted slightly outwards to replace the conventional tail fin/rudder and tailplane/elevator combination. There are also four engines under the additional wing area and a wide body designed to accommodate up to 750 passengers on long-haul flights. The simulated flying wing boasts a wingspan of nearly 100 m (328 ft), length of 65 m (213 ft) and maximum take-off weight of roughly 700 tons. Together, its four engines provide a maximum thrust of 1,425 kilonewtons.
During the flight tests to explore the flight characteristics of the flying wing design the DLR team examined individual maneuvers, such as varying the aircraft's altitude and using a simulated instrument landing system to test approaches on a virtual runway. Evaluations of the flying wing's handling characteristics were carried out after each maneuver, which confirmed that the flying wing aircraft is difficult to control due to its unusual shape. However, DLR says that the introduction of an additional DLR-developed control system that initiated appropriate counter-measures was able to prevent the aircraft from responding adversely to pilot inputs.
"The flight test confirmed our assumptions," said Leibling about the results. "There is a limit to handling a modern, completely uniquely-shaped aircraft without coordinated flight control laws. We can only achieve the flight characteristics we want by using appropriate computer and control technology."
ATTAS has been in service for 25 years and by working its simulated, shape-shifting magic during a real test flight, the DLR team says the aircraft has allowed it to confirm in a 'tangible' way the preliminary results of theoretical investigations. So, with its special capabilities, the 25 year-old ATTAS could be paving the way for the passenger aircraft of tomorrow.
As an engineer I understand how much time they can save and how valuable simultions and simulators are, but they are only as good as the models and data that drive them, mankind has been caught out too mant times by effects that we poorly understand or didn\'t even realised existed. Great work but proceed with caution!
This \"new\" design is closer to Burnelli\'s favored design, the Lifting Fuselage. See his actual planes here. http://www.burnelli.com/Welcome.html The opening page shows Burnelli\'s last design before his death in 1964, a 400/500 passenger, supersonic airliner.
Don\'t think this design could go supersonic? How about hypersonic? Compare this design with NASA\'s X-43B and X-51 hypersonics. (X-43A flew at Mach 9.6, X-51 Mach 5 /-). Google, Images of these designs. All are Lifting Fuselage designs with flat or slab sides, strikingly similar to Burnelli\'s supersonic plane. (And yes, composites are now proven to hold an atmosphere with this design.)
Still don\'t think Burnelli\'s work was right on? Check out what a Langley, Sr. Aeronautical Engineer had to say. http://www.meridian-int-res.com/Aeronautics/Burnelli_AIAA.pdf Then read research in layman\'s terms, that explains the superiority of the Lifting Fuselage design. http://www.meridian-int-res.com/Aeronautics/Burnelli.htm
I\'m workin\' on it. http://www.aviationpeopletalk.net/ (Halfway down the page)
And therein lies the problem. Many \"believe\" or \"think\" or \"don\'t see\" that this wing could work based on their experience. Even one NASA aeronautical engineer made the off-the-cuff comment about the Burnelli Lifting Fuselage 20 some years ago. He said, \"I would think it would have horrendous induced drag.\"
With no background what-so-ever in the study of the Lifting Fuselage, even people with extensive aerodynamic educations will just blurt these statements out. I would think he may have changed his mind since NASA has gone this route to achieve hypersonic speeds more efficiently. Both the X-43 or X-51 designs are relatively fat airfoils and yet this is needed to \"reduce\" induced drag.
In the 70\'s, Boeing was even considering making a cargo transport using Burnelli\'s design. Their own research numbers showed more than twice the cargo capacity of the 767 using the same amount of fuel to go the same distance. You cannot have these kinds of results if you have \"any\" amount of overall drag. I CANNOT be done. In the real world, Burnelli\'s actual planes out performed every other similarly sized and powered tube and wing design of every decade his planes flew. This CANNOT be done with excessive drag. CANNOT!
Oh, the reason Boeing did not complete the airframe of the Boeing 754 Husky International was because at the time the Burnelli design was still under patent. The Burnelli Company asked Boeing for a 1% licensing fee. Boeing refused to pay it and tore down the framework they had already begun and we all lost out. Carrying twice the cargo for half the price means lower prices for goods around the world. And, now that this can be built with composites (also for 1/2 the price), airfares could drop dramatically.
Check out Boeing\'s model of the 754 HI here... http://www.king5.com/news/business/Boeing-planes-that-never-flew-116515378.html
For anyone with similar reservations as windykites1, please look at the meridian site in my last post as well as the Boeing numbers included on the meridian page. http://www.meridian-int-res.com/Aeronautics/Burnelli.htm There is much to be learned about this design if one will take the time to find it. The site, http://www.aircrash.org/burnelli/sitemap.htm , is filled with reports and observations by organizations and people with first hand knowledge of Burnelli\'s designs.
I\'m workin\' on it. So can you.
By the way... A swept wing is not made for and gives no advantages for supersonic flight. It is only for the trans-sonic region ~mach .93-.99