Jarosław Naleszkiewicz's Naleszkiewicz JN-1, nicknamed Żabuś II (Froggy II; the Jach Żabuś was an earlier, unrelated Polish glider) was an experimental tailless glider which was intended to test the behaviour of a proposed twin-engined aircraft of the same configuration.

It was preceded by a series of rubber-powered models which proved flight stability and suggested good performance.

[1] In essence the wooden JN-1 was a high aspect ratio, cantilever wing with a short, bulbous central nacelle and wingtip vertical surfaces.

It was not repaired because of a mixture of funding problems, a lack of official interest and Naleszkiewicz's absence due to a new job in Warsaw.

[1][2] With its differentially operating rudders it may have the first glider fitted with air-brakes,[2] though of a very different type to the spoilers used a few years later on German sailplanes.