To: Dave Jackson
Even if Leonardo had a 1000 HP engine driving his screw it most likely would not work as designed. The Archimedes water lift operated on the same principle when he invented it and it is still in use under various forms today to raise water from one low point to a higher point or, to provide liquid under pressure from one point to another. The reasons it works are two fold. One the operating fluid is denser and the other reason is that there is a close tolerance duct around the screw. If Leonardo had the 1000 HP engine and he had a duct around the screw it might have worked. Today, it's called a gas turbine.
Sikorsky used this principle to deliver oil to the outer bearing of the CH-37 tail rotor gear box and the Apache electronics air conditioning system also uses Archimedes screws in the compressor.