Now there is something different..
https://www.flightglobal.com/helicop...138504.article
Meanwhile, Bell also appears to be seeking to bring to rotorcraft the performance gains fixed-wing aircraft have obtained from the use of split-tip winglets, such as those produced by Aviation Partners for the Boeing 737NG.
The patent application for the split-tip rotor blade notes that in wind-tunnel testing of the design, lift rose by about 13.5% and drag reduced by about 17%. “Accordingly the lift/drag ratio was increased by about 36.91%”. This, Bell says, “can result in fuel savings of about 15-17%”.
Bell was granted a US patent for the design on 21 April. Although the airframer gives no detail of specific applications for the split-tip rotors, a drawing within the patent documents shows an aircraft bearing a strong similarlity to its 505 light-single.