25 Jan Supersonic speed through swept wings
Adolf Busemann laid the foundations for supersonic flight over eighty years ago, with his concept of swept wing aircraft. It was Busemann who made it possible for us to fly further and faster.
Busemann‘s aviation innovation: cutting through the air like an arrow
The German aerodynamicist, Adolf Busemann, made a significant contribution to the development of modern passenger flight with his innovative swept wing concept. A pupil of the aviation research pioneer, Ludwig Prandtl, Busemann held positions in the field of high-speed aerodynamics at various institutes including the Kaiser Wilhelm Aerodynamic Research Institute in Göttingen, taught aerodynamics at Dresden Technical University and worked at the German Experimental Aerospace Centre in Berlin-Adlershof. From the earliest days of his career, Busemann constantly dreamed of smooth, high-speed flight, with supersonic flight an almost unimaginable dream in the 1930s. As soon as an aircraft approached the sound barrier, the flight control surfaces no longer functioned effectively, the plane began to vibrate, and it was no longer controllable. However, Busemann sought to create a completely new kind of wing design, with the aim of breaking the sound barrier for the first time.
As an aircraft approaches the speed of sound, aerodynamic resistance on the load-bearing surfaces increases so significantly that it becomes impossible to fly any faster. Adolf Busemann recognised this problem and found a highly innovative solution in the form of the swept wing.
His concept, which involved adjusting the wing sweep (the angle between the wing and the axis of the aircraft), reduces the resistance exerted by air on the load-bearing surfaces. This increases airspeed while reducing fuel consumption. The revolutionary swept wing concept meant that the aerodynamic prerequisites for supersonic flight had been fulfilled.
In 1935, at the age of 34, Adolf Busemann presented his innovative idea to a specialist audience at the fifth Volta Conference in Rome. Unfortunately, his idea was not well received, as the technical requirements to achieve higher speeds were not yet in place. However, Busemann did not allow himself to be discouraged and continued to pursue his research into the topic.
Busemann’s wing construction
The aviation researcher, Hubert Ludwieg, successfully provided a proof of Busemann’s principles in 1939 at the Göttingen Aerodynamic Institute through the use of empirical measurements of the swept wing design.
In a high-speed wind tunnel, Hubert Ludwieg used small models with varying swept angles but equal profiles to demonstrate Busemann’s theory that aircraft can fly faster as air resistance is reduced. On the basis of the measurements that were taken in Göttingen, further experiments were performed in larger high-speed wind tunnels.
After the Second World War, the findings that resulted from these measurements came as a surprise to the Allied specialists. They did, however, now recognise the full impact of Busemann’s swept-wing concept. Allied aircraft projects that were already in the planning phase were halted and Busemann’s theory, in combination with wind tunnel measurements, was taken into account as aircraft were redesigned. Boeing, for example, completely reworked the wings of the B47 to incorporate Busemann’s swept wing concept. The world’s first large, long-range passenger airliner, the Boeing 707, was also built with swept wings.
Supersonic flight thanks to swept wings
Since the 1950s, this ground-breaking concept has formed the basis for modern aviation. Even today, swept wings remain in use, for instance in the Airbus A380, a modern passenger jet.
The most famous swept wings are those belonging to the Concorde, the Anglo-French supersonic airliner, which operated between 1976 and 2003. Nicknamed the “Pocket Rocket ” at the time, the plane flew at almost twice the speed of sound, thanks to its delta wing design. This design of wing is used on supersonic aircraft in particular, and the design is a development of the swept wing concept that takes its name from its resemblance to the Greek letter, Delta. The greater swept angle creates a large area inside the Mach cone (the area over which the shockwave from breaking the sound barrier is distributed). Additionally, in subsonic flight, delta wings offer greater air resistance than traditional wings, with greater extension given the same amount of lift. Another example of the swept wing concept in use is the Belgian-developed Verhees Delta Plane 1. The ultra-light aircraft is made from aluminium tubing and sheet metal and also has a delta wing.
Today, 20 years after Concorde’s last flight, several companies are once again working intensively on the development of civil supersonic aircraft that could significantly reduce travel times. Two of the most promising projects are Boom Supersonic and Aerion Supersonic. These companies are using advanced technologies, including aerodynamic innovations and powerful engines, to make supersonic travel more economical and environmentally friendly. Efforts are also focused on minimizing the disruptive effects of sonic booms to promote the acceptance of this technology. With promising prototypes and investments in development, we could witness a new era of civil supersonic flight in the coming years.
Thanks to the work of Adolf Busemann and Hubert Ludwieg, the swept wing is a firm fixture in the world of aviation technology that continues to be developed. Adolf Busemann’s swept wing makes it possible for us to fly faster and further. We’d like to dedicate this blog article to Busemann and Ludwieg and offer them our thanks.
Sources: DLR | TU Darmstadt | American Institute of Physics | DLR | Spiegel Online