Hi to all!
Answer to dear Meteorit.
Disignations of M-19 (Kholod-2 progtamme):
M-19 (pure) - so called "Gurkolet" = spaceplane+hypersonic bomber
M-19-1 - "fat" laboratory in Aeroflot markings
M-19-2 - pure hypersonic bomber
M-19-3 - shuttle (almost dubble sized Buran)
M-19-4 - shuttle bigger than M-19-3
M-19-4V - swept wing hypersonic bomber (look like Tu-160)
and three more exotic variants of MDB (soon will follow)
And next (the 5th) variant of M-50.
Addition info wil be soon in www.avicopress.ru