VTC Delfin 1
This Yugoslav single-seater high performance Standard Class sailplane was designed by T.Dragovic and Z. Gabrijel, two young engineers at the Faculte des Siences Mathematiques in Belgrade, and the prototype, known as the Delfin 1, made its first flight in December 1963. It made its public debut at the 1965 World Championships at South Cerney in Gloucestershire, and went into production as the Delfin 2 at the Vrsac works of VTC – Vazduhoplovno Tehnicki Centar (Aeronautical Technical Centre).
The Mk 2, which first flew on 26 April 1965, differed from the prototype in having the plywood fuselage covering extended to cover the nose, a smaller sideways opening canopy, a rubber-sprung nose skid added and wooden instead of metal ailerons, and 27 of this version were built, four of which were later converted to Delfin 3s. The Delfin 2 achieved its first real competition success when it came 1st and 2nd in the Polish National Championships of 1966, no mean feat in view of the strength of opposition from the indigenous SZD designs.
The Delfin 3 first flew on 29 July 1968 and has a conventional tailplane instead of an all moving one, reduced fin sweepback and increased rudder area. It is of plywood-covered wooden construction; the cantilever shoulder wings have plywood-covered leading edges and fabric-covered rear portions, and wing tip 'salmon' fairings are fitted. There are metal Schempp-Hirth air brakes above and below the wing surfaces at 60% of the chord. The fuselage is a monocoque structure with a small cross-section made possible by putting the pilot in a semi-reclining position under a one-piece curved flush fitting cockpit canopy that opens sideways to starboard for entry and exit. The swept back fin is integral with the fuselage, and the fixed tailplane has a trim tab in the starboard elevator. Landing gear consists of a non-retractable unsprung monowheel with a mechanical brake and a rubber-sprung nose skid, plus a tail bumper.
Span:49 ft 2.5 in
Length: 22 ft 5.5 in
Height: 5 ft 3 in
Wing area: 138 sqft
Aspect ratio: 17.55
Empty weight: 492 lb
Max weight: 717 lb
Max speed: 155 mph (in smooth air)
Min sinking speed: 2.13 ft/sec at 46.5 mph
Best glide ratio: 31:1 at 54 mph