The Nimbus motorcycle was pretty unique in itself, following their own path for design. Previous post. Their concept for a new modern engine design in the fifties continued the original thinking.
Rotary valve four stroke engines have been tried multiple times, the issue seems to be the heat that accumulates in the parts. The resulting distortion of the valve results in poor sealing, galling and possible seizures. This experimental Nimbus concept seems to address many of the issues, the valve is alternately cooled by the incoming charge and heated by the exhaust and the spring loaded bearing mount should allow for any distortion of the valve. The floating valve ports further lessened the problems of heat distortion.
But it also appears that this spring loaded valve forms the top of the combustion chamber and would the force of combustion not force the valve upwards each time? Perhaps the drawing is not correct or maybe that's the reason this engine never went into production.
During 1941 and '42, the US did some R&D tests in Canada involving fitting skis to fighter planes. Several configurations were tried on the Kingcobra, it tended to run in a broad curve due to engine torque. Experiments with runner length on the skis cured most of the taxiing and takeoff maneuverability issues but upon landing, the right ski tended to dig in. Eventually the idea was given up as being impractical.
By the casting numbers on the hub, this was a production wheel. Ten 1/2" diameter spokes riveted to a simple steel band with a lap joint. The spokes are about 1/2 inch diameter, secured with good square nuts. We suspect they came from some farm implement, and will do duty on a cart for a 8 hp Gilson stationary motor. After about a hundred years they're still round enough...