While there was a Russian engineer involved, the PZL M-15 "Belphegor" was a Polish design and built in Poland.
The obvious answer is hibernation. This will greatly reduce the body's need to consume a lot of food during the flight there and back.
It could never compete with the C-5, a far larger and more capable aircraft in every sense.
ALL engines produce exactly the same torque at zero RPM; and that is zero Nm.
Sounds like you've been smoking too many "joint dreams".