Time to head for the skies, vertically, slowly and a long time ago.
Meet the Flettner Fl 282 Kolibri.
Open or closed according to when it was made. Surprisingly, to me at least, it went from closed (the first two prototypes) to open. Just 24 were made.
It was powered by a seven cylinder (because even numbers of cylinders are boring) 7.7 litre radial engine by Siemens, a company not now known for engines. The interesting thing was the rotor arrangement, like so:
Two of them, intermeshed, so no tail rotor. Despite appearances they don’t bump into each other as each rotor rotates around an axis that is tilted slightly to the outside of the helicopter. The idea was revived after WW2 by Kaman in the US which you might think a complete coincidence except that Anton Flettner emigrated (or was persuaded to emigrate) as a result of Operation Paperclip and wound up as Kaman’s chief designer.
Want to see it flying? Here we go in glorious colour.
Flettner’s ideas about rotors didn’t end with helicopters because the Flettner Rotor was further developed as a means of providing power from the wind as opposed to supplying power to it as was usually the case in aircraft. The E-Ship 1 uses four Flettner rotors to assist the engines, so a kind of marine hybrid. It’s a complicated arrangement because the ship uses waste heat from the exhaust to produce steam which drives a turbine (by Siemens, as it happens - see above) and produces electricity which spins the four vertical tubes. Provided that the wind is in the right direction (90 deg to the direction of travel) these then produce a propelling force courtesy of the Magnus Effect.
It may not be immediately obvious, but she’s travelling right to left.
Naturally enough she’s owned by a wind turbine maker and used to transport turbines.