Applied Aerodynamics

Flying Wings: One Solution to Improve Tomorrow's Air Traffic

 
Numerical simulation of the flow around a blended wing body

Passenger and cargo air traffic is expected to grow about 5% a year over the next 20 to 30 years. In the short term, this will require the deployment of more jetliners which will in turn worsen air traffic congestion and pollution.

The conventional jetliner configuration, with a cylindrical fuselage, a swept wing and empennage, and engines mounted on pylons under the wing, was developed nearly fifty years ago. Over the years, jetliners have grown considerably to meet market demand. The next generation, the Airbus A380, will be the largest commercial transport ever built, carrying 555 passengers in a 3-class layout.

Large capacity aircrafts have to fit in a 80-meter sided square.

Designing such a large capacity aircraft brings up new challenges. It requires much more than a simple extrapolation from previous aircraft, for several technical reasons including limits on overall dimensions: to be able to operate from most existing airports, the airplane footprint cannot exceed 80 meters square.

The conclusion is obvious: to deploy even larger aircraft (carrying over 600 passengers), we will have to use non-conventional configurations. Only ultra-high-capacity aircraft will enable us to keep pace with steady air traffic growth, while reducing congestion and pollution.

Preliminary studies have shown that a flying wing is a viable concept for the ultra-high-capacity configuration, and offers the potential for significant improvement in terms of both aerodynamic and structural efficiency. In a flying wing, the payload is housed in a thick wing eliminating the conventional fuselage and empennage.

It also reduces the wetted area and spreads the payload and systems across the span, thus providing bending alleviation. Although the principle is seemingly simple, the characteristics of these configurations fall outside the scope of currently available huge amount of database and experience for civil transport aircraft.

Onera and his German counterpart, the DLR, have decided to pool their efforts on the flying wing, via a joint cooperation called "Performance Assessment of Integrated Wing Fuselage Configurations", with two main objectives in mind:

• To increase the general knowledge in the critical areas of the aerodynamics, stability and control along with structural conception of the flying wing aircraft configuration;

• To develop design rules as well as tools to assess this kind of unconventional aircraft.

The disciplines investigated within the DLR-Onera cooperation are mainly:

• Aerodynamics,

• Structure and weight,

• Stability and control (S&C), including low-speed wind tunnel tests.

Two "extreme" configurations have been selected as benchmarks for validation purpose:

Flying wing configurations

As far as aerodynamics is concerned, the objectives of the activity carried out in the Applied Aerodynamics Department are:

• To define a methodology for high speed wind tunnel testing;

• To define a methodology to extrapolate performance in wind tunnel conditions to flight conditions;

• To perform aerodynamic optimization (see Aerodynamic Optimization Of Subsonic Flying Wing Configurations for more details);

• To lead the low speed wind tunnel model design and testing in the Onera S5 wind tunnel (see pictures below).

For more details, see "Flying Wing Aerodynamics Studies at ONERA and DLR"

Dynamic structural computation of a flying wing wind tunnel model
(DRIM/Lille)

View of a flying wing model in the Onera S5 test section

Last Update:5 April 2006 - © ONERA 2009 - Terms of use