I stumbled across this photo of my 1970s helicopter; hingeless rotor with semi-floating hub, Canadian Kohler 440cc snowmobile engine and curved tail rotor driveshaft.
It hovers with the left skid low because left cyclic is required to resist tail rotor thrust and rotor hub is connected to the driveshaft via a stiff “U” joint made from Chevrolet engine mounts.
The tail rotor driveshaft ran at ~5,000 rpm, well above critical speed and if not curved, would have required support bearings every couple of feet to keep it stable.
It hovers with the left skid low because left cyclic is required to resist tail rotor thrust and rotor hub is connected to the driveshaft via a stiff “U” joint made from Chevrolet engine mounts.
The tail rotor driveshaft ran at ~5,000 rpm, well above critical speed and if not curved, would have required support bearings every couple of feet to keep it stable.
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