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Old 08-28-2012, 01:52 PM   #30 (permalink)
mort
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Hello meanjo

Quote:
Originally Posted by meanjoe75fan View Post
Diesel dave: you mentioned compressor/turbine combos at 50% efficiency...better tgan piston power. Then wny not delete the piston portion and go with a pure turbine engine? I was told in my flying days that a piston would handily beat a turbine in "power-specific fuel consumption": is that no longer true?
What Dave was referring to is mechanical efficiency, not thermodynamic. The best low power turbines can return about 20% thermodynamic efficiency. And conversely the mechanical efficiency of a piston as compressor and expansion engine is better than 95%.
-mort
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