Type Project Two seat trainer
Engine 1 Gnome-Rhône  Jupiter
Dimensions Length  , height  ,  span  , wing area   ,
Weights Empty , loaded  , max. take off weight  
Performance Max.. speed  , cruising speed  , range , endurance  , service ceiling   , climb
The Raab-Katzenstein RK 28 was designed in 1929 by Richard Bauer as a military training aircraft for advanced training in the Raab-Katzenstein works. The engine was a 460 hp nine-cylinder Gnome-Rhône Jupiter engine. The aircraft was offered in 1929 at a unit price of 60,000 RM.

This design may have been developed as a result of the Swedish Air Force's interest in the Raab-Katzenstein RK 26 Tigerschwalbe, which, however, did not meet the requirements for Class II training aircraft in Sweden, as a further development with a more powerful engine. Development came to a halt after Richard Bauer left in the autumn of 1929 and was not resumed in 1930 due to the economic situation at Rheinische Luftfahrt-Industrie GmbH in Krefeld.