Standard calculations were also insufficient, so simulation was needed.
The discussion had persisted for years because there was no way to answer the question definitively using wind tunnel testing.
Glider airfoil design software#
Structural aspects of the design could be looked at in Mechanical and composite solutions in Ansys’s Composite PrepPost software, meaning only one software supplier was required.įirst, the engineers applied ANSYS Fluent to solve a question that had been puzzling sailplane engineers for several years – what is the best place to connect the wing to the fuselage for the least drag? Some had argued that attaching the wing at a high position on the fuselage prevents detachment of the boundary layer airflow from the aircraft body, leading to less drag others contended that attaching the wing to the middle of the fuselage requires a smaller connection cross section, thus reducing drag, while simultaneously increasing the undesirable boundary flow detachment phenomenon. The company opted to use ANSYS simulation software for finite element analysis and the computational fluid dynamics aspects, which could be analyzed in Fluent. Contracting the work out to universities proved to be too expensive, inflexible and not conducive to building in-house expertise. Answers for aerodynamicsĪS Sailplane engineers started the project with an in-house analytical tool that the company had been using for several years, but they soon realized that it would be insufficient for the task. Because most of the sailplane is made of composite materials, except for the metal landing gear and mechanical control system, engineers explored an all–carbon-fibre design instead of the commonly used combination of glass fibres and carbon fibres embedded in a polymer matrix. Engineers also wanted to investigate if connecting the wing high up on the fuselage was better than a mid-fuselage join in terms of strength and drag.Īn additional challenge was to optimize the winglets - the small, upturned tips of the wings - which reduce vortex airflow at the ends of the wing, further reducing drag. A smaller wing also has less space for structural elements, so engineers needed to improve the design so that the wing can carry the same loads while maintaining strength. Reducing the wing surface area produces less lift, so the aerodynamics of the system must be improved to compensate. The change required the team to overcome a host of challenges. While that may not sound like a big design change, it is massive in an aircraft that has been around for a long time and is already very close to its optimal design. By keeping the 18m wingspan constant, they produced a wing with a smaller average chord and therefore a reduced wing thickness.
While the wingspan and thickness are very close to practical limits, AS Sailplane engineers believed the surface area could be reduced from 10.5 square meters to 10 square meters to cut the aerodynamic drag significantly. They have an 18m wingspan and a 10.5 square meter wing surface area, with a wing thickness of only 10cm. The AS-33 glider made its maiden flight in January 2020 from Huhnrain Airport near Frankfurt in Germany (Image: Alexander Schleicher) Aerodynamic, structure and materials challengesīest-in-class gliders used in competitions weigh from 400kg to 600kg.