What is "kholod"

Kholod is the name of a project which was originally developed in Russia. The hypersonic rocket uses a scramjet engine and was created to exceed the speed of 5.75 Ma. The prototype consists of a Soyuz TMKB with liquid hydrogen and modified fillings from the SA-5 Gammon missiles. The entire rocket including the four booster rockets is long and in diameter. The project led to other Russian hypersonic rockets like the Igla rocket craft and the Yu-71 boost-glide warhead.