Are there airplanes without a fuselage

With the flying wing into the air

Without a fuselage, the distribution of the payload across the entire aircraft area promises lower kerosene consumption. After initial implementation in military aviation, large, civilian flying wings could carry up to 750 passengers in the future.

Model of a flying wing passenger jet

The planes of the future could glide through the air as elegantly as a ray. Instead of a cylindrical fuselage with attached tail unit and wings, the “flying wings” only consist of a flat shell with a triangular outline. Above all, the developers expect better aerodynamics from this design. The envisaged goal: to fly much quieter with radically reduced kerosene consumption. The lower noise level could be achieved by a shadowing effect of the engines, which would be mounted above the wings.

Flying wing concepts are more than 100 years old

Natural role model for flying wing jets

As futuristic as the flying wing concepts appear, the idea for the unusual fuselage shape is over 100 years old. In 1903 the Austrian Ignaz Etrich was inspired by the flying seeds of an Asian climbing plant - Zanonia macrocarpa. The seeds can only sail a few hundred meters through the air if they are covered by a transparent, ten centimeter wide flight membrane. Etrich secured a patent for this flying wing in 1905, but at that time it was not enough for a real airplane.

In the decades that followed, numerous prototypes were created based on the flying wing concept. In the 1930s, the Horten brothers in Germany constructed a motor glider that was powered by a stern propeller. Even a fighter, which due to its shape should hardly be located by radar waves, was developed under the leadership of the German Air Force during World War II. However, it was never able to take off and land safely. The idea of ​​flying wings was picked up by American aircraft developers in the post-war period. But it stayed with the prototypes Northrop YB-35 and Northrop YB-49.

Military flying wing prototype

To date, only one American military jet has come close to the visions of a flying wing. Without a tail unit, the long-range bomber B-2 Spirit is in service with the US Air Force. Because of its low-edged structure, it is considered to be a stealth aircraft that is difficult to locate by radar waves. The aerodynamic advantages, on the other hand, are of secondary importance and the control is also considered so difficult that it should only be possible with intensive support from computers. The flight of the Boeing X-48 experimental aircraft is said to be more stable. The prototype with three small jet engines and a wingspan of 6.4 meters has made 80 successful test flights over the past four years. Another version with only two jet engines is to follow soon.

Only in the last few years has the civilian use of flying wings returned to the interest of aircraft developers. The focus is on thrift. "With the same payload, you could save up to 20 percent fuel," says Carsten Liersch, aircraft expert at the Institute for Aerodynamics and Flow Technology at the German Aerospace Center (DLR) in Braunschweig. However, this cannot be precisely assessed today, as many points have not yet been clarified. In order to learn more about flying wings, the DLR, together with the aircraft manufacturer Airbus and numerous European partners, has now developed several concepts and finally models for a “Very Efficient Large Aircraft” - VELA for short. The bulbous flying wing could accommodate up to 750 passengers.

More buoyancy with the same cabin volume

“All in all, such flying wings have a much less flow around surface than a conventional jet with the same payload volume,” explains Liersch. This significantly reduces the frictional resistance and flight noise. To get an idea of ​​the aerodynamics of flying wings, the scientists also took measurements in the wind tunnel.

Comparison of lift distribution

Due to the flying wing shape, the aircraft's bending moments were much smaller than with a fuselage-wing construction. The result: with the same stability, less material would have to be used and the curb weight would decrease. But the biggest advantage lies in the completely new aerodynamics of the winged ones. “The lift is produced where the load is,” says Liersch. In conventional aircraft, the air flow on the wings creates the necessary lift and has to lift the “lift-free” central cabin tube as a kind of ballast. Just under half of the entire surface of the jet provides lift. In the case of the flying wing, on the other hand, it is around 97 percent - which is why the engines can be smaller and therefore more economical.

In parallel to the wind tunnel tests, the DLR researchers also analyzed the pressure distribution along the VELA surfaces using complex computer simulations. Thanks to the flying wing shape, these loads are distributed more evenly over the entire outer shell. With modern materials such as fiber-reinforced composite materials, which are already being used in the first conventional jets, a sufficiently stable yet comparatively light construction is possible. However, these first VELA models cannot take off and land.

The first test models take to the air

Researchers led by Rudolf Voit-Nitschmann from the Institute for Aircraft Construction at the University of Stuttgart dared to take this next step. Based on the VELA models, they constructed a flying wing prototype with a 3.3 meter wingspan. It is powered by a jet turbine for model aircraft. Remote-controlled, this flight model completed several test flights and could be accelerated to up to 200 kilometers per hour. This flying wing could be maneuvered safely even without supporting computer programs. Packed full of numerous sensors - from pitot tubes for speed to acceleration sensors for the forces acting on the structure - the researchers were able to collect a lot of data on flight behavior.

Wind tunnel tests with the VELA model

"For us aerodynamicists, these model flights are not that interesting," says Liersch. Because the behavior of a model airplane on a scale of 1:50 cannot simply be transferred to a large passenger jet. The important aerodynamic key figures such as the Reynolds number, which can be used to describe the turbulence behavior of bodies in a flow, differ greatly from an aircraft on a 1: 1 scale. With regard to the stability of a flying wing, such model fliers are not very meaningful, because, for example, the natural vibrations, which must be avoided due to resonance effects, are in a completely different frequency range. In addition, according to Liersch, the wing loading and the ratio between weight and thrust are also relevant parameters that can only be transferred from models to larger aircraft to a limited extent.

Even Liersch cannot predict whether a flying wing with a wingspan of one hundred meters will ever take off. The acceptance by the passengers also plays an important role. On the one hand, up to 40 people would have to sit in a row; window seats would be the rare exception. In addition, significantly greater acceleration forces acted on the fringes even with a gentle turn. “I think it's rather questionable whether passengers actually want to endure this,” says Liersch. Therefore, utilization plans are being worked on in which the passengers will not sit right up to the edge of the aircraft. “There is certainly still some research to be done,” said the DLR researcher. The civil flying wing is still a major challenge, but it could be overcome.

Profitability is decisive for the success of the flying wing development

Last but not least, the economic efficiency of the flying wing will also play a decisive role. But is a fuel saving of 30 percent actually enough to justify billions in development funds for a large flying wing? “There is no question that it works in principle,” Liersch is convinced. But right from the start, a flying wing should be better and more economical than the designs of conventional aircraft that have been optimized for 50 years. A demanding goal with high pressure to succeed: "Because aircraft manufacturers cannot afford a flop from a new development."