Chernov Che-25
The Chernov Che-25 is a four-seat, twin engine parasol wing amphibious flying boat built in Russia in the 1990s. The Che-27 is an enlarged, five seat version. Design and development. The Che-25 is very similar in general appearance to earlier Boris Chernov designs such as the two seat Korvet and the Chernov Che-23 but is a four-seat aircraft, with both span and length increased. It has an unswept, straight edged constant chord wing made from riveted duralumin, with a single spar. Lateral (roll) control is by full span flaperons and stability on the water is maintained  by downturned fiberglass tips which act as simple floats. The parasol wing is braced by a single streamlined strut on each side to mid fuselage, assisted by jury struts, flying wires and a central section cabane. The twin engines are mounted above the wing leading edge. They can be either Rotax 582 UL-2V air and water cooled, twin cylinder two strokes or Rotax 912 ULS water cooled four stroke flat fours. The Rotax 582s are mounted uncowled and drive a two bladed propeller but the 912 installation is cowled, with three-bladed propellers. The Che-25 has a flat sided, two  step hull formed from a vacuum moulded fibreglass sandwich. The integral fin forms a cruciform tail with a swept, tapered, straight edged fin initially carried a balanced rudder, though the Che-25M variant with its higher tailplane abandoned the balance. The underwing cabin has dual controls and is entered via gull wing doors. There is a water rudder attached just aft of the rear step. The optional land undercarriage has mainwheels on mid-fuselage mounted legs, which rotate forward through 90° to allow water landings, and a tailwheel fixed to the water rudder. The Che-25 was built by the  student design bureau SKB-1 and first flew in 1995. It appeared in public in September 1996 at the Hydroaviasalon show in Gelendzhik. The Che-25M was displayed at the 1999 MAKS airshow, Moscow. Current production plans are not known. Variants. Data from Jane's All the World's Aircraft 2009-10 References. http://www.sama.ru/~chernovb/che25.shtml