TYPE: Four-seat lightplane.

PROGRAMME: Development of original Ruschmeyer MF-85 started in Germany in 1985; first prototype MF-85P-RG (V0001) flew with Porsche engine; changed to R 90-230 RG using flat-rated Textron Lycoming IO-540 after cessation of Porsche production in March 1990; first flight of prototype V001 (D-EEHE) 8 August 1988; first flight of V002 (D-EERO) 25 September 1990; V003 (D-EERH) first flight 12 February 1992; LBA certification June 1992; FAA 24 June 1994. Main production variant was R 90-230 RG, of which 25 built; Ruschmeyer also produced prototype fixed landing gear R 90-230 FG; lower and higher-powered versions were overtaken by company's bankruptcy. Programme transferred to Solaris in USA, 1999; German-built R 90-230 RG registered N230S in June 2001 as demonstrator. Production deliveries due to begin in third quarter of 2002, but no production reported by late 2003, at which time the Type Certificate remained in Ruschmeyer ownership.

CURRENT VERSIONS: Sigma 230: One Textron Lycoming IO-540-C4D5 flat-six, derated to 172 kW (230 hp). Retractable landing gear; intended for European market.
Alpha 230: As above. Fixed gear.
Sigma 250: IO-540-C4D5 engine, fully rated at 186 kW (250 hp). Retractable gear. Baseline US version.
Alpha 250: As immediately above. Fixed gear.
Sigma 310: Teledyne Continental IO-550N flat-six, rated at 231 kW (310 hp). Retractable gear. Uprated US version.
Alpha 310: As immediately above. Fixed gear.

COSTS: Sigma 250 US$244,900; Sigma 310 US$279,900 (2002).

DESIGN FEATURES: Objectives were FAR Pt 23 compliance; high performance by low-drag all-composites airframe, use of derated engine for European version, requiring less cooling, reduced noise by lower engine rpm, special silencer and, originally four-blade constant-speed propeller. Consequently, reduced fuel consumption and emissions; noise level under German regulations demonstrated 66 dBA, 8 dBA below limit; also 10.2 dBA below ICAO Chapter 10 limit. Laminar flow aerofoil. Certified 18,000 hour life.

FLYING CONTROLS: Conventional and manual; all push/pull rod operated to minimise friction; dual controls with sticks standard; fixed tailplane; combined trim and trim tab on port elevator; stall strips on inboard wing leading-edge; three-position Fowler flaps operated by electrohydraulic system are linked to elevator to avoid trim changes; max feflection 30°. Aileron deflections +16/-11°; elevator +18/-15°; rudder starboard 240 mm (9.45 in), port 220 mm (8.66 in).

STRUCTURE: All-composites moulded airframe with 70 per cent fewer parts than equivalent metal structure. Ruschmeyer qualified BASF Palatal A430 resin fibre composites material for aviation; advantages are durability at up to 72°C ambient, improved strength, field repair without special tools, negligible allergic risks during manufacture, and material is recyclable. GFRP with Rohacell foam cores and CFRP reinforement round doors; steel tube running from firewall, over roof and into tail, supports doors and protects against roll-over; components earth bonded to German and FAA standards. Meets 1.75 safety factor for composites airframes.

LANDING GEAR: Retractable tricycle type; electrohydraulic actuation; trailing-link levered mainwheel suspension retracts inward and covered by mechanically linked doors; foot-powered hydraulic disc brakes; steerable nosewheel retracts rearward, also covered by doors.

POWER PLANT: As for Current Versions. Hartzell three-blade, constant-speed propeller. Adjustable cowl flaps. Standard Sigma 250/Alpha 250 fuel 311 litres (82.0 US gallons; 68.3 Imp gallons) in integral tanks in inner wings; Sigma 310/Alpha 310 349 litres (92.0 US gallons; 76.7 Imp gallons). Oil capacity 11.4 litres (3.0 US gallons; 2.5 Imp gallons) for Sigma 250/Alpha 250; 12 litres (3.25 US gallons; 2.7 Imp gallons) for Sigma 310/Alpha 310.

ACCOMMODATION: Four-seat interior with ergonomically designed seats; three-point harness; upward-opening gull wing doors; heating and ventilation system with electric blower; baggage compartment accessible from inside and outside.

SYSTEMS: S-Tec 40 (optional 55X) single-axis autopilot. Electrohydraulic actuation for flaps; pitot heater and night lighting. Electrical system 28 V DC; 70 Ah alternator; 24 V 18 Ah battery.

AVIONICS: Comms: Garmin GNS-430 transceiver; GTX-327 transponder; GMA-340 audio system; ELT. Optional GNS-530 nav/com with GI-106 moving map indicator.
Flight: Garmin GNS-420 GPS. Optional second GNS-430, S-Tec ST-180 slaved compass, ST-361 flight director, ST-360 altitude selector, Goodrich WX-500 Stormscope and Shadin fuel/air data computer.