The Kamov-XX is an experimental helicopter aircraft conceptualised by the russian company Kamov, which specialises in helicopters. The Sputnik's perk was that it had not one, but two, Warthog-like engines in its tail that could highly increase its speed.

The aircraft has two modes, the default helicopter mode (AG8) and the fixed wing (plane) mode (AG7)

To switch between them, you'll need to first slow down at 0% speed (wait for the rotors to slow down), turn off the current mode, speed up at 100% speed then press the other mode.
(Please note that the "Fixed Wing mode" is extremly unstable due to the rotors, if you want to get into a fight, you should convert to helicopter mode first.)