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Here's a pic of their blades layout:
http://batman.mech.ubc.ca/~hph/thunderbirddesign.gif (note the blade rotation arrows) What I'm wondering about the blades: - Why the odd taper? I'm guessing the taper alleviates tip losses, but why does it begin at the ~.6 span mark? I'd expect taper across the entire blade for the best inflow results, but then again I'm a non-expert. - Why no twist? Does the taper alone sufficiently linearize the inflow? I'd be grateful for any thoughts on these questions, and I know that probably no one in this newsgroup has an exact answer. I'm just a student studying helicopter aerodynamics and am interested in the UBC HPH design. Here are some of their CFD visualizations if it helps anyone analyze: http://batman.mech.ubc.ca/~hph/projects/cfd.html And here's some info on another HPH design, with blades that are more conventional (to my knowledge at least): http://www.calpoly.edu/~wpatters/davi.jpg Hope someone here knows more about this than I do, jc |
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James;
Mike Georgallis was the person at UBC who was in charge of the project. His phone number is/was 604 822-3665. He would be the best person to provide the answers to your questions. A few thoughts; The UBC rotors were very large and very slow turning. My impression was that the two disks should be smaller and identical. Normally a smaller disk will require more power. However, the slow speed of the these blades meant that they were not operating in a vertical flow field. In addition, these blades would have flex in the flapping direction. The flex recovery, as the blades pass through the downwash/downdraft of the blades of the other rotor, should maintain a fairly consistent angle of attack throughout the rotation. Constant taper and ideal twist should also help. Dave "james cho" wrote in message ... Here's a pic of their blades layout: http://batman.mech.ubc.ca/~hph/thunderbirddesign.gif (note the blade rotation arrows) What I'm wondering about the blades: - Why the odd taper? I'm guessing the taper alleviates tip losses, but why does it begin at the ~.6 span mark? I'd expect taper across the entire blade for the best inflow results, but then again I'm a non-expert. - Why no twist? Does the taper alone sufficiently linearize the inflow? I'd be grateful for any thoughts on these questions, and I know that probably no one in this newsgroup has an exact answer. I'm just a student studying helicopter aerodynamics and am interested in the UBC HPH design. Here are some of their CFD visualizations if it helps anyone analyze: http://batman.mech.ubc.ca/~hph/projects/cfd.html And here's some info on another HPH design, with blades that are more conventional (to my knowledge at least): http://www.calpoly.edu/~wpatters/davi.jpg Hope someone here knows more about this than I do, jc |
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