The Ayaks is a hypersonic aircraft program started in the Soviet Union and currently under development in Russia by the Saint Petersburg Institute for the Hypersonic Systems of Leninets Holding Company. The concept of the aircraft was developed by Vladimir Freishtadt in the late 1980s as a response to the American Aurora aircraft program. The Ayaks was initially supposed to be produced in three variants:
- As a platform for launching satellites into space;
- As a multi-purpose hypersonic military aircraft; and
- As a hypersonic transport aircraft.
The design of the aircraft utilized a number of novel and controversial ideas that only in 1993 were officially recognized as conforming to modern science.