Information about this constructions I found in very interesting book "All Jane's Aircraft (issue 1993)", where I found first data about ESAG (Experimental Sport Aviation Plant) and SSAKTB (Special Sport Aviation Design and Technological Bureau) - now known as AB SPORTINE AVIACIJA!

The LAK-12 2R is two-seat Open Class version of the Lietuva, designed by Mr. Anatas Rukas and Mr. Algimantas Jonusas. Construction of the prototype began in 1985, and the first flew in April 1986. By March 1988 a second aircraft had been completed. Compared with the single-seater, the Lietuva 2R has a reinforced fuselage structure with a modified control system, a modified and reinforced retractable lending gear with a brake and bungee suspension. 100 liters of water ballast in wing tanks, and tandem seats in longer fuselage.

Technical data LAK-12 2R

Dimensions, weights, loading and performance

Wing span	20.42 m
Wing area	14.63 m2
Fuselage length	7.73 m
Height	1.92 m
Wing aspect ratio	28.5
Empty weight	400 kg
Max. T-O weight	690 kg
Max. water ballast	100 kg
Max. wing loading	47.16 kg/m2
Best L/D at 115 km/h	48
Minimum rate of sink at 80 km/h	0.5 m/s
Stalling speed	70 km/h
Max speed (smooth air)	250 km/h
Max speed (rough air)	175 km/h
Max aero-tow speed	140 km/h
G limits	+4/-2

LAK-15

This was a single-seat Open Class sailplane, designed for setting records.
AIRFRAME: Cantilever mid-wing monoplane of large span. Four section airfoil. Dihedral 3 degrees. Carbonfibre spar and three-ply glassfibre/carbonfibre skins. Airbrake, two flaps and aileron on each wing. Composites fuselage and integral fin. T tailplane. Retractable monowheel, to be fitted with brake, with shock absorber. Fixed tailwheel. Water ballast in wings.

Technical data LAK-15

Dimensions, weights, loading and performance

Wing span	25.6 m
Wing area	17.4 m2
Fuselage length	8.2 m
Height	2.19 m
Wing aspect ratio	28.5
Empty weight	385 kg
Max. T-O weight	750 kg
Max. wing loading	43.10 kg/m2
Best L/D	59

SSAKTB SL-2P

First flown on 25 June 1987, the SL-2P is a flying laboratory for airfoil research, joining two standard L-13 Blanik sailplanes and using an SA designed center wing and center tailplane. Further details and an illustration, can be found in the 1988-98 Jane's.