This is out third prototype of a Tesla turbine. Here we are trying to determine the best running speed of the turbine. Top speed is 6350 rpm at marker 9:52. This is in excess of 414 mph at the outer blade at less than 50 psi. The resonance frequency of the turbine is between 4250 and 4500 rpm. At 4700 rpm the turbine exceeds this frequency, the vibration ceases and the efficiency improves. 5400 looks like a viable operating speed for this 22 inch diameter turbine. The blade assembly weighs 56 pounds.