RE: New Italian Q500
From Wikipedia, I'm not sure if anyone has done objective testing on our racing models.
Wingtip devices are usually intended to improve the efficiency of fixed-wing aircraft.[1] There are several types of devices, and though they function in different manners, the intended effect is to reduce the aircraft's drag by altering the flow near the wingtips. Wingtip devices can also improve aircraft handling characteristics, and enhance safety for following aircraft. Such devices increase the effective aspect ratio of a wing, with less added wingspan. An extension of span would lower lift-induced drag, but would increase parasitic drag, and would require boosting the strength and weight of the wing. At some point there is no net benefit from further increased span. There may also be operational considerations that limit the allowable wingspan.
The wingtip devices increase the lift generated at the wingtip, and reduce the lift-induced drag caused by wingtip vortices, improving lift-to-drag ratio. This increases fuel efficiency in powered aircraft, and cross-country speed in gliders, in both cases increasing range.