Su-75 has zircon hypersonic air ducts to withstand higher speed loads

In the Su-75, as in the Zircon, the air duct passes through the fuselage to the engine mounted in the tail section. It has already been proven by international aviation engineers, specialists, and designers that such a structure is capable of withstanding incredibly high speeds and colossal overloads. It is also less prone to overheating the fuselage at ultra-high speeds.