The R 90 was a new design based on the Ruschmeyer's earlier MF85, making use of a range of modern technologies and materials. The MF85 series was powered by Porsche engines, but the unavailability of these powerplants led to the development of the Textron Lycoming powered R 90.
The Ruschmeyer R 90 possesses an aerodynamically clean airframe made possible by its glass fibre (with Rohacell core) construction. The advanced wing design features a `rain tolerant' laminar flow aerofoil design, wet wing fuel tanks, upturned wingtips (for increased lateral stability, not drag reduction), small ailerons and inboard Fowler flaps.
A four-seat touring and IFR training monoplane first flown in 1991 and certificated 1992, the original R90-230 RG version with 230 hp engine and retractable undercarriage was to be joined by the R90-180 RG with a 180 hp engine and retractable undercarriage. Development of the definitive production version began in 1992 being followed by a production batch of 15 in the same year.
The initial R 90-230 RG production model was powered by a fuel injected Textron Lycoming IO540 flat six driving an advanced four blade composite construction propeller. A silencer on the engine, the four blade prop and the engine being derated to 170kW (230hp) from 195kW (260hp) combine to give low interior and exterior noise levels. Even though the engine has been derated, because of the R 90's comparatively light structure its performance is quite strong.
All production R 90s were the high performance retractable undercarriage R 90230 RG. This model first flew on August 8 1988 (as MF.85), with German certification awarded in June 1992.
Members of the planned R 90 family include the fixed gear, 175kW (235hp) O540J powered R 90230 FG and the fixed undercarriage 135kW (180hp) IO360 (flat rated to 150kW/200hp) powered R 90180 FG. The R 90350T RG, to be powered by a 185kW (250hp) turbocharged engine and capable of 435km/h (235kt) cruising speed, and the high performance five/six seat R 95 were also under development. An Allison 250B17 turboprop powered development, the R 90420 AT proof-of-concept model, was flown in 1993 and used only as a factory aircraft.
However Ruschmeyer was forced to file for bankruptcy in early 1996 and production has ceased. Twenty-two R 90-230 RGs were built before production ceased.
In 1999 Solaris Aviation was founded, and purchased the assets of Ruschmeyer. Solaris Aviation marketed the R90 as the Solaris Sigma.
R 90-230 RG