Matt Prather wrote:

Is the shroud like an exaggerated winglet?  Instead of a full shroud,
could you get most of the benefit of the shroud by designing the prop
tip with a winglet?  'Course the problem with the winglet is that it would
be operating in the spanwise location with the highest airspeed, and
would benefit from a relatively thin airfoil - making it difficult to
structurally
attach it.   Maybe that's why we're seeing swept tips (Hartzell Scimitar) -
control the tip vortex, but leave the tip thin - actually, that's probably a
transonic airspeed drag reduction method.

The hoop can be structurally stronger with more blades supporting it -
allowing a thinner junction between the blade and the hoop - reducing
interference drag.

It seems like static thrust can be gotten most effectively from increased
blade area.  Controlling the tip vortex with a winglet (hoop) is a 'trick' to
make up for not having enough blade area?  So the hoop is a good solution
where you are prop diameter limited, or where you want to protect the
prop tips from FOD.

Sorry for thinking out loud (in e-space).

Regards,

Matt-

 
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