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HpH's TwinShark is the next generation 20 meter two seater sailplane. This sailplane is already showing strong promise among its competitors; the Arcus and ASG-32. The Twin Shark prototype was revealed in April 2017 at AERO in Friedrichshafen. The empty weight is 50 kg less than the Arcus and 75 kg less than the ASG-32! Performance will be strong with wing laminar flow up to 95%. The Twin Shark is available as a pure glider, self launch and jet sustainer.
Prior to development and design there was extensive discussion among gliding clubs and individuals. There was a strong pilot interest to keep the flying, ergonomic and high quality characteristics in line with the popular single seat HpH Shark.
The Twin Shark development team was set up from top-rated Czech research organizations. Part of the team includes aerodynamic specialists from the Academy of Sciences of the Czech Republic IT AS, VSP R & D, who hold the 2010 OSTIV Diploma. This was lead by Lukas Popelka, acting as chief aerodynamicist. Also working on development are Brno University of Technology team of Robert Popela and Zdenek Patek’s team from Aeronautical Research and Test Institute (ARTI).
The primary design effort was in wing development. Five new main airfoils were designed which enable a smooth contour span wise. A multi-criteria optimization was applied in the airfoil design taking into account 72 parameters. Low drag in high speed glide is achieved with a laminar boundary layer up to 95% chord of the airfoil lower side. Lift curves of the Twin Shark's positive flap settings show steady and continuous increase of lift when raising the angle of attack. This allows better use of a thermals dynamic potential as pioneered by L.M.M. Boermans, OSTIV President. Lift slope courses were proven in wind-tunnel measurements showing strong capability even for low Reynolds numbers in the wing tip area. In addition, substantially higher maximum lift coefficients were obtained.
Wing sections were tested in IT AS and ARTI wind tunnels, using aerodynamic balances and pressure measurement; infrared technology which confirmed the designed laminar flow.
The Twin Shark has an elliptic wing both in planform and dihedral. Trapezoid sections were completely ruled out. In order to reach true elliptic lift distribution and eliminate vortex generation on section joints trapezoidal wings were eliminated. The new Twin Shark design has smooth-shaped winglets.
Wing and fuselage junction advancements were accomplished with the help of a full 3D CAD model. Design variations were compared by CFD software code calculations, modeling the complete sailplane in various angles of attack and speeds covering the entire operational range. One of main contribution of this analysis was on flowfield on fuselage downstream the wing and on wing angle of incidence setting related to fuselage axis. Additional wind-tunnel testing was executed in IT AS, expanding the mentioned OSTIV renowned case on wing-fuselage interaction.
|Wing Span||20 m||65.6 ft|
|Wing Area||15.1 m2||162.5 ft2|
|Fuselage Length||8.95 m||29.36 ft|
|Profile||PW 10-145 14.5%||PW 10-145 14.5%|
|Empty Weight||480 kg||1158 lbs|
|Max Take-Off Weight||850 kg||1874 lbs|
|Water Ballast||120 l||31.7 US gal|
|Min. Wing Loading||36 kg/m2||7.36 lb/ft2|
|Max Wing Loading||56.3 kg/m2||11.51 lb/ft2|
|Best Glide Ratio||49||49|
|Best Glider Ratio @||128 km/h||69 kt|
|Min. Sink Rate (at min. weight)||0.5 m/s||141 ft/min|
|Min. Sink Rate @||92 km/h||50 kt|
|Stall Speed (at max. weight)||68 km/h||37 kt|
|VNE||275 km/h||148 kt|