To: Dave Jackson. .. .Quote:. .. .“Thanks. I found 29 patents that involved Coanda effect and rotor blades. They are interesting ideas, but if Coanda cannot provide enough force to offset rotor torque it probably will not give enough force for lift”.. .. .Response:. .. .I do not know what torque you are referring to. The upper surface blowing does not provide much propulsive force to rotate the blades. The tip discharge jet nozzle performs that work.. .. .To: heedm. .. .Quote:. .. .“Lu, was there any mention of the power penalty required to pump high velocity air through all the blades?. .. .Granted, that penalty gives you a safety benefit, but if it considerably reduces your envelope, then it may not be desirable overall”.. .. .Response:. .. .I am not knowledgeable relative to the engineering aspects and how much power is required to provide the propulsive force. What I do know is that the helicopter design had two gas turbine engines coupled to shafts that drove turbine compressors, which provide the compressed air. The jet efflux is passed down twin booms and provides some forward thrust and the efflux impinges on control vanes for directional control. The compressor discharge passes through air ejected intercoolers which minimizes the temperature of the air passing down the blades.