Several companies and groups have developed a series of designs which began at an offshoot of the Trod
Kuznetsov aircraft engine plant in
Samara. Beginning with the L-3, they differ in size and engine type but all are twin engine amphibians with a characteristic V tail. The L-4 is a direct development of the L-6M, promoted by AeroVolga. Its design began in August 2004. All L-4 variants have the same layout and all are largely built of
composite materials. They are
high-wing monoplanes with twin engines mounted close to the
fuselage, on top of the wing. The wings have straight taper on both edges and almost square
tips. The L-4 has a pair of
flaps on each wing. Its hull has two
steps and there are small winglets at
water level just aft of the
trailing edge. The cabin extends from below the
leading edge rearwards to the winglets. Fixed
floats under the wings stabilize the L-4 on water; it is operable with waves to 400 mm (15 in) high. The most unusual feature of the L-4 is the
empennage arrangement: it has twin
fins, mounted on the fuselage and extended forward with long, curved dorsal fillets, separated at the base by the full fuselage width and leaning slightly outwards. The fins carry conventional
rudders and the single
tailplane is mounted upon the fin tips, extending well beyond them. Tailplane and single piece
elevator together are
trapezoidal; there is a
trim tab at the centre of the elevator. The reason for the design is that the spine serves as a walkway to access the plane from behind, when moored at shore. The L-4 has a
conventional undercarriage for land use, all three wheels and the
water rudder being retractable. The first flight of the L-4 was in June 2005. The most recent variant, the more powerful L-44 flew in 2009. ==Operational history==