The Oblique Flying Wing Page

 

Northrop Grumman's concept of what the OFW X-Plane will look like in flight, showing a side view and (inset) top view.
From left to right: at Mach 0.6 with 0 degrees of wing sweep; at Mach 0.79 with 45 degrees sweep; and at Mach 1.2 at 65 degrees sweep. 

(These are frame grabs from a 26 second animated sequence 15 MB wmv file.) 

 

DARPA and Northrop Grumman are working on a program to develop a new X-Plane, called an Oblique Flying Wing (OFW). The OFW X-Plane will be the first supersonic flying wing and the first tailless OFW. An OFW is an aircraft without a fuselage that can vary the angle of its wing with speed: as the aircraft accelerates to supersonic, one side of the wing sweeps forward and the other side sweeps back. As a result, an OFW is capable of efficient supersonic flight and also has excellent low speed endurance.

 

 OFW X-Plane drawing)

  Northrop Grumman image of their X-Plane demonstrator concept. 

 

DARPA Information on OFW

 

Northrop was selected for the contract in March 2006.


DARPA released a Broad Agency Announcement (BAA) requesting proposals to develop an OFW in August 2005. The BAA proposer information pamphlet (PIP) has a detailed discussion DARPA's plans for the program.

 

OFW Technical Primer

 

Desktop Aeronautics, Inc., has conducted extensive studies in unconventional aircraft and published a white paper on OFWs in June 2005. Desktop Aero also has an extensive bibliography of oblique wing research papers.

 

 

Oblique Wing Demonstrator History

 

An in-depth history of oblique wing research has just been published by the American Institute of Aeronautics and Astronautics (AIAA)! A locked PDF is available for download on this website (5 MB).

 

The idea of oblique wing aircraft has been around for over a half century, going back to the Blohm & Voss P.202 in World War II. Much of the early theoretical work was done by R.T. Jones of NASA Ames. In the last 30 years, a number of small test aircraft were flown to proven that oblique wing aircraft can fly. After testing small gliders, two small unmanned aircraft that used an oblique wing on a fuselage, followed by the manned AD-1, were flown by NASA. All of these demonstrators had tails and none of them were flown at high speeds.

 

NASA Ames oblique wing radio controlled model with a 5.5 ft wing span (circa 1970).
It flew with sweep angles beyond 45 deg. (Photo courtesy of the NASA Dryden Flight Research Center.)

 

NASA Ames oblique wing remotely piloted vehicle (first flight 1976). Maneuvers were performed at wing angles of 0 to 45 degrees.
For more information, see the NASA oblique wing RPV web page. (Photo courtesy of the NASA Dryden Flight Research Center.)

 

Ames-Dryden AD-1 oblique wing demonstrator (first flight 1979). It flew with the wing at angles from 0 deg up to 60 deg and speeds up to 170 mph.

More information at NASA's AD-1 website. (Photo courtesy of the NASA Dryden Flight Research Center.)

 

Under a grant from NASA Ames, Dr. Steve Morris at Stanford University built and flew two oblique flying wings (i.e., no fuselage). These were the first powered oblique flying wings to fly. The first model was a 10 ft span OFW powered by a propeller. This was later followed by a 20 ft span OFW with two ducted fans. Both of these small-scale aircraft used vertical fins to provide directional stability and control. 

 

Steve Morris’ 10 ft OFW (first flight 1993). It flew at sweep angles of up to 65 deg. (Photo courtesy of Dr. Steve Morris.)

 

According to the Stanford press release, the flight tests “proved that the unstable wing configuration can be flown.” On his website, Dr. Morris has a copy of his contemporary AIAA paper with details of his OFW development. Additional information and photos were published in "On The 'Wing..." newsletter; a high resolution in-flight photo can be found on the Stanford University website.

 

Steve Morris’ 20 ft OFW (first flight 1994). It flew at sweep angles between 35 and 68 deg and a maximum speed of about 65 mph.

 (Photo courtesy of the Hiller Aviation Museum).

 

In addition, supersonic wind tunnel tests were conducted at NASA Ames of an oblique flying wing. The OFW model was tested between Mach 1.56 and 1.80, and at a fixed sweep angle of 68°.

Ames Wind Tunnel Test Model

NASA Ames supersonic wind tunnel model (1994). (Photo courtesy of the NASA Ames Research Center.)

 

Numerous other design studies and wind tunnel tests have been conducted over the past 50 years. The DARPA OFW X-Plane, however, will be the world’s first tailless OFW and will be the first to demonstrate the benefits of an oblique wing at supersonic speeds.

 

 

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Last updated on August 21, 2007.