Soviet NKL-16M 'Hydrosan'
Okay, like a lot of my Builds, this one's been planned for quite a while, and waiting for an opportunity to build it, so here we are . . .
The major problem the Soviets found with their aerosani was that they could only be used when the lakes and rivers were frozen, and snow was present on the ground. Although the Soviets also had aeroglisseri, aero engine powered speedboats for use when the rivers and lakes were ice-free, they couldn't be used in winter, or on land. Further neither type could be used during the rasputitsa, or spring thaw, when the water was liquid, but not ice free, and the snow had thawed, and the ground was just mud. What was needed was a single type of craft that could operate in all these conditions.
The answer, when it came, was simplicity itself. Starting with a damaged NKL-16 transport aerosan, it's skis were removed and replaced with a pair of floats from a scrapped Junkers airliner, dating from the time of pre-war Russo-German pact. The ski equipped aerosan steered by pivoting it's skis, which was impossible with the floats attached, so the linkages were re-arranged to operate a rudder mounted in the propeller's slipstream. As the floats were all metal, no reinforcement was needed to allow them to run over snow and ice.
The modified NKL-16M proved highly effective, and orders were issued to convert all aerosani to this new configuration, which the Soviets called a Hydrosan. In addition, all further aerosani were to be built as Hydrosani. Fortunately, the drawing for the Junkers type floats still existed, enabling them to be put back into production, and for the lighter aerosan types, smaller existing wooden floats could be used, suitably reinforced with metal keel plates for running over ice.
The NKL-16M is probably most famous for it's use during the siege of Leningrad, when it was used as a high-speed* courier, on Lake Ladoga, both during the winter on the ice road 'Road of Life', and in the summer when the lake had thawed.
*relatively speaking; the NKL-16M was capable of 40 mph on open water and smooth snow and ice, less on mud and ice containing water.
Cheers,
Robin.