[russss]

> Here incomming air is highly compressed -- and thus heated up -- due to impacting plane parts at hypersonic velocities.

The problem is that at high mach numbers, the incoming air is too hot to successfully combust. They have to chill it (using the cryogenic fuel), and chilling it would usually result in icing.

The whole point of these tests is to prove that their precooler system resists icing.