Hi Anthony,
Hijacked the answers from the HKN-forum:
The Mi6 appears to have been released by a former Soviet company, named Plastikart. According to some HKN forum members, scale must have been somewhere in between 1:72 and 1:100... The opinions on the quality of the kit vary with the scale estimates.
The Mi26 is (to be?) released in 1:72 by Sanger. Sadly but understandibly it's a vacuform kit. Sanger must have a website, but the URL I have doesn't work.
Good Luck!
Gertjan Zwart