Aerodynamics

From wind tunnel to super-ellipse

Normally irreconcilable: best climbing performance, an excellent glide ratio - even at high speeds, optimal thermalling performance, and all in all very good-natured handling characteristics.

These goals could be reached with the Antares. The aerodynamic design is the result of a multi-year research project. We have exploited all conceivable possibilities to optimize our glider, and designed it uncompromisingly all of a piece. We used and perfectly harmonized ten different wing airfoils to minimize drag. The laminar flow on the wing’s bottom surface reaches up to 92% of its depth. Zig-zag tape finally forces the laminar flow to transition to a turbulent boundary layer. On the airfoil’s upper surface the circulating air stays laminar until having followed up to 75% of its depth. This currently represents the best indicated value for airfoils which do not utilize boundary layer suction technique. When flying at high speeds you can take advantage of an additional negative flap setting (- 3°). So, in the end you may fly at very high speeds and at the same time achieve a so far unreached gliding performance. Only at speeds over 220 km/h / 119 kts to 245 km/h / 132 kts (depending on your actual wing loading) these airfoils tend to fall out of the laminar flow.

Wing geometry

The Antares 21E’s wing geometry is described by an extremely slender super-ellipse. Thanks to this shape, the induced drag is reduced to its theoretical minimum. It corresponds to the ideal value of an untwisted and elliptical shaped wing, without having to fear the critical stall characteristics inherent to such a wing. The deep-gauged outer wings are responsible for good-natured flight qualities. Plus, our winglets reduce the induced drag by another 5%. In total the 21.5 meter wingspan’s induced drag only measures 95% compared to an untwisted elliptic wing.

Detail perfection

The Antares 21E’s wing area is big enough and well dimensioned to meet a motor glider's requirements.

In combination with a high aspect ratio of 35.8 it guarantees superior climbing qualities at a minimized induced drag.
  • Wings and winglets have been drafted in one unit. Perfectly matched with the wings our winglets thus significantly reduce drag and at the same time boost the flight qualities.
  • The electric propulsion unit’s compact engine helps to realize an optimal contraction of the fuselage’s cross section which further reduces aerodynamic drag.
  • Common aerodynamic loss of performance in the wing-fuselage fillet is minimized by a specific layout of the fuselage section and through using particularly turbulent airfoils in the area close to the fuselage.

Handling

The Antares 21E is thanks to its full-span flaperons incredibly well maneuverable. The flaps’ regulation is based on a novel control system. Additionally we could significantly reduce friction resistance in the entire control system by consequently using high quality ball bearings instead of slide bearings. The result are extraordinarily smooth controls.

Big rudder control surfaces with high aspect ratios and state-of-the-art airfoils guarantee for perfect control under any circumstance in flight and in any wing loading configuration. Meanwhile these control surfaces only produce a minimal drag.

Highly extendable three-stage Schempp-Hirth air brakes make for always safe landings. Even at steep approach angles the glider does not loose much of its buoyancy. So with extended brakes the stall speed increases only a little bit.

All these factors make the Antares 21E a smoothly maneuverable and most agile sailplane. Yet it does not seem “nervous”. Our Antares 21E flies stable, reacts very well and will tell you about any thermal activity in the air. Its maneuverability is comparable to a 15 meter glider. For example, rolling around the longitudinal axis with a neutral flap setting+ / - 45° at a speed of 115 km/h / 62 kts will only take 3.4 seconds. Antares 21E: Open class performance combined with 15m-class handling!