how to design small diameter high static thrust rotor?
how to design small diameter high static thrust rotor?
(OP)
Guys,
I'm interested how one could design a "small" diameter rotor with high lift.
I've read that the most efficient *theoretical* (in terms of lift to drag) rotor system is a large diameter rotor with one "long" blade, and that the most efficient *practical* rotor is a large diameter rotor with 2 blades
So assuming you wanted to keep LIFT the same as you reduce rotor diameter...
AND that your upper limit for rotor speed is < the speed at which the blade tips exceed the speed of sound...
So what other possible option remains but to add more blades to the rotor ??? and since you've added more blades, drag increases, so you've got to add more power...
So "heavy lift" helicopter designers simply add more blades (and more horsepower) because there is no other way to get more lift? (of course assuming they can't increase rotor diameter or tip speed also)
Thanks for any advice or clarification.
Mike
I'm interested how one could design a "small" diameter rotor with high lift.
I've read that the most efficient *theoretical* (in terms of lift to drag) rotor system is a large diameter rotor with one "long" blade, and that the most efficient *practical* rotor is a large diameter rotor with 2 blades
So assuming you wanted to keep LIFT the same as you reduce rotor diameter...
AND that your upper limit for rotor speed is < the speed at which the blade tips exceed the speed of sound...
So what other possible option remains but to add more blades to the rotor ??? and since you've added more blades, drag increases, so you've got to add more power...
So "heavy lift" helicopter designers simply add more blades (and more horsepower) because there is no other way to get more lift? (of course assuming they can't increase rotor diameter or tip speed also)
Thanks for any advice or clarification.
Mike





RE: how to design small diameter high static thrust rotor?
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: how to design small diameter high static thrust rotor?
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: how to design small diameter high static thrust rotor?
If you want to stick with free rotors, various tip designs like the BERP attempt to kill spanwise flow and/or act as supercritical airfoils. Of course there's the basic route where you play with the blade itself (airfoil shape, alpha, blade twist, etc). Ray Prouty's books would be a good source for the aerodynamic aspects of blade design. I took a course from him and learned more of the basics in a few days than I did in an entire semester of VTOL in school.
RE: how to design small diameter high static thrust rotor?
Also for an example of a Ray Prouty article see here
http://www
A lot of his articles were available on the Internet previously . . but maybe not anymore. <(
RE: how to design small diameter high static thrust rotor?
http://www.unicopter.com/1464.html
Dave J.
RE: how to design small diameter high static thrust rotor?
With a propeller, or a rotor, with winglets, wouldn't that act as a ducted fan with infinite small gap between fan and duct?
Is there any experience with such a configuration?
Per Magne Lunde