Akaflieg Braunschweig SB-14

The SB 14 was designed to minimalist principles, reducing wetted area and use of high speed aerofil sections in a high aspect-ratio wing. As an economy measure, the tail unit of the Schleicher ASH 26 was utilised. To improve performance of the wing in a wide range of conditions, the wing-tips have swept wing-lets, as well as turbulators forward of the flaps on the undersurface of the wings.[1]

The SB 14 is a shoulder-wing sailplane constructed from carbon-fibre composite materials. The wings are of very high aspect-ratio and incorporate full span flaperons with slots for when the flaps are extended. The fuselage follows contemporary design practice with a cockpit pod and slender rear fuselage terminating in a T-tail. The cross section of the fuselage has been minimised throughout, reducing wetted area and therefore minimising drag.[1]

Control is through conventional elevator and rudder with full span slotted flaperons on the wings and Schempp-Hirth airbrakes on the upper surfaces at about 1/3 span. The undercarriage is a conventional retractable mono-wheel main undercarriage with a steel tipped rubber block tail-skid under the fin.[1]

Flight testing, from 17 January 2003, revealed very promising performance, optimised with various aero-dynamic refinements.[1]

Data from [1]

General characteristics

• Crew: 1
• Capacity: payload (pilot + equipmqnt) 96 kg (212 lb) ; Water ballast 160 kg (350 lb)
• Length: 6.95 m (22 ft 10 in)
• Wingspan: 18.00 m (59 ft 1 in)
• Height: 1.23 m (4 ft 0 in)
• Wing area: 10.84 m² (116.7 sq ft)
• Aspect ratio: 29.89
• Airfoil: root: CA2-134 / 15V2 ; tip: CAJ1-134 / 18
• Empty weight: 285 kg (628 lb)
• Max takeoff weight: 541 kg (1,193 lb)

Performance

• Never exceed speed: 272 km/h (169 mph, 147 kn)
  
• Minimum speed: 70 km/h (43 mph; 38 kn)
• Maximum glide ratio: 50:1 (approx)
• Rate of sink: 0.5 m/s (98 ft/min)
• Wing loading: 33.9 kg/m² (6.9 lb/sq ft) to 50 kg/m² (10 lb/sq ft)

• All-Aero.com