The Bristol Sycamore
Wooden blades, each a tower flown set. No hydraulics, spring feel via a lateral and fore/aft trims wheels. A collective /throttle interlink which initiated a vague, sometimes opposite response to collective inputs. A nine cylinder supercharged radial engine that would operate at MAP and RPM figures in the hover that were regarded as emergency figures on it's fixed wing predecessor. Appalling control authority and prohibited from night flying out of the airfield area.
I did 50 hours basic training on those. The subsequent 16,000 hrs. were a breeze.