So far my autogyro rotor blades have been with squared off tips (as the Cabeeza DC Gyro). Would rounded tips be more efficient? Any comments?
Colin Duthie

Hi Colin, I have never experimented with tip shape, but it must be important, as I see some full-scale rotorcraft with swept or curved tips these days. Back in the 1980's, I built ultralight airplanes. Some advanced models, such as the Rotec Rally Sport, as well as the famous reflex wing Kasperwings, had wing tip plates. Kasperwings even had multi-hinged tip plates, allowing it to make controlled vertical descents. Many full-scale birds use tip plates or droop tips. Seems there is room for experimentation. Perhaps some model helicopter manufacturer has already conducted such experiments. I'll have to look in some back issues to see what has been done. Happy Flying !!! Charlie Anderson

Perhaps a vertical winglet would give some kind of benefits! Sincerely, I doubt there can be important or noticeable gains with that, at least in helis they just use rounded tips. Of course, their blades work in a quite different way. A 45ΒΊ bevel cut may be all that's needed, but after all it's easy to experiment with bolt-on wingtips or tip shapes...
As for me, I'd rather make a "whistleng tip" so that when I make descents with the engine at idle I can enhance that blade sound which sends shivers down my spine and makes me smile (something between [>:] and ).