This is the version that uses atmospherically compressed air as the motive medium and heat as the fuel. There is another version with a combustion chamber and two Tesla valvular conduits. This version gets hot. I would be using an aluminium casing for that version. The discs are designed to run at supersonic speeds in the turbine / rotary engine. Spring steel because it yields slightly at very high RPMs. At 52,000rpm the rotor will be transonic and clouds will form inside the turbine. The turbine will condense the water and the pump will eject water from the exhaust. Good point on the CTE. Something to think about. I’ve been thinking a better way might be to forge the discs. I’d welcome material suggestions. My aim is to build the fastest rotor possible. The current bearings I have are designed to run at 156,000rpm which would be Mach 3. I aim to build air bearings capable of running from atmospheric pressure just like Tesla used. New Way off the shelf air bearings sell some 1/4” air bearings rated at 140,000rpm but require 60 psi. My aim is to learn and to teach with a bit of banter. Belittling people I’m not a fan of.