Fieseler had recently won a world aerobatics championship with an RK-26.

It was tested with different engine configurations by Flygvapnet, who later ordered 25 aircraft from ASJA.

When the Winter War began, Hemmeninger donated the aircraft to Finland.

The aircraft ended up being used by the Swedish Voluntary Air Force from 9 February 1940.

Data from Thulinista Hornetiin[1]General characteristics Performance