Wikipedia
ANT-IV
The ANT-IV was one of three aerosans introduced in 1924. This model, operated by a crew of two, doubled the ANT-III's with its new Bristol engine, and outperformed the ANT-V's Fiat engine.
In 1930 the ANT-IV began regular trips between Cheboksar and Kanash, carrying mail and priority passengers. The following year the ANT-IVs were overhauled with Soviet-produced M-11 radial aviation engines, allowing them to travel at 28 km/h.
In 1934, an ANT-IV was delivered aboard the Smolensk to Ualen where it helped rescue remotely stranded explorers from the icebreaker Chelyuskin.