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Surely the main reason for a variable-pitch prop (on a piston engined aircraft) has got to be fuel efficiency. Like a car gearbox, it enables you to match the engine to the load in a hopefully optimal manner. If you put a Spitfire engine in a car then you probably wont need much of a gearbox... but you will pay a heavy price in fuel consumption. If one wasnt worried about fuel efficiency then I cant see what difference there could possibly be between reducing the prop pitch and simply reducing engine RPM if the objective is to fly slower - both methods will reduce the thrust and the aeroplane cannot know the difference. >I know how it works (sort of!), and I know the settings to use in the PA23 >Apache, but how do you really use the constant speed/ variable pitch prop? >What does it do (apart from the obvious) that the fixed pitch one doesnt? > >Say you want to decrease speed whilst remaining straight and level. I know >that in the PA23 I select 18"/2300 (down from 22"/2300) and maintain >altitude by pitching up. I know that because Ive been taught it by the >venerable George Orive, CFI. But why do I do that? Whats the theory behind >the reduction in power? > >What Im really trying to ask is for a comprehensive guide of what the blue >lever and the black lever really do to your aircraft. > Peter. -- Return address is invalid to help stop junk mail. E-mail replies to zX80@digiYserve.com but remove the X and the Y. Please do NOT copy usenet posts to email - it is NOT necessary. |
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