The Quintus M is a completely redesigned 23-meter aircraft and was presented to the trade public for the first time at AERO 2011 by the two cooperation partners Lange Aviation and Schempp-Hirth. The Antares 23E and the Quintus M differ mainly in the fuselage, the outer wings and the respective propulsion technology. While the Quintus M is self-launching thanks to a 70 hp internal combustion engine from Solo, the Antares 23E boasts an innovative electric motor. Concept and design of the inner airfoils were done by Lange Aviation and Prof. Loek Boermans. Nine precisely matched profiles with laminar run lengths of 95 percent on the bottom and 75 percent on the top were used, based on a superelliptical floor plan. The outer wings of the Quintus M were designed by Schempp-Hirth with the help of Karl-Heinz Horstmann and Jan Himisch of DLR Braunschweig, while the winglets were developed by Prof. Mark Maughmer. The flaps or ailerons run over the entire wingspan and thus allow very effective and direct control movements. It is also noteworthy that at the beginning of the project in 2011, the verification for the wings was initially performed for the agreed weight of the non-load-bearing parts GNT (loaded fuselage and tailplane) for 380 kg. After it became apparent that this GNT was not tenable, refinements to the verification process in 2013 increased the allowable weight of the nonstructural parts to 403 kg and, in early 2015, to 403 kg plus filling of the wing tank near the fuselage in the left wing. This example shows nicely that considerable reserves can lie dormant even in highly stressed components.