The Moskalyev SAM-10 was a late 1930s Soviet light transport aircraft suited to passenger or ambulance roles.
They had twin spars with plywood skin around the leading edge and fabric covering aft.
[1][2] The undercarriage was fixed and conventional with mainwhels on oleo struts, enclosed in aerofoil section trouser fairings, and a skid under the tail.
Its outstanding performance resulted in orders for both passenger and ambulance configurations but the unavailability of its engine blocked production.
[1] Data from Osprey Encyclopedia of Russian Aircraft 1875-1995[1]General characteristics Performance