Originally Posted by
Robbo Jock
Bolt a vertical flat plate on the end of each rotor blade - that'll cut down on the vortices and hence noise. Shimples.
As you probably know, each bit of mass one adds to a blade has an impact on vibration signature and the three dimensional loading back at the hub/cuff.
With that considered, quite a few rotor blade designs currently in use apply geometric variations to reduce vortices. (The one I am most famiiar with is on the S-70 family by Sikorsky). The idea of putting something like a "stall fence" out near the blade tip has probalby been tried, but not adapted due to what is does to some other feature of the design. (There are trade offs everywhere, eh? )
Hopefully, the continuing quest for noise abatement can find some areas to improve without putting a damper on performance.