Partenair Mystere

The Partenair Mystere is a Canadian two-seat, pusher configuration monoplane that was designed by Partenair Design of Saint-Jean-sur-Richelieu, Quebec and intended for amateur construction from kits.

Two prototypes were completed and flown and one kit delivered before the project was ended. One customer-built S45 was eventually completed and first flew on 10 November 2015.

Design and development
The Mystere is an all-composite, low-wing monoplane powered by a pusher piston engine. It has a pod and boom configuration with a T-tail and a fixed tricycle landing gear with wheel pants. The cockpit has room for two occupants in tandem with dual controls and a two-piece canopy and windscreen.

The prototype S44 Mystere first flew on 16 November 1996 powered by a Rotax 912 engine. The second prototype S45 was powered by a 160 hp Lycoming IO-320 flat-four piston engine and first flew on 4 October 2001.

The kit was to be supplied in three sub-kits made from primer-surfaced parts of low-odour epoxy. The construction time from the kit was estimated to have been 1,000 hours.

Variants

 * S44 Mystere
 * Initial 80 hp Rotax 912UL powered version. Empty weight 700 lb and gross weight 1250 lb, cruise speed 140 mph. The price of the complete S44 kit, including engine in 1999 was US$38,000. Only one prototype was flown.


 * S45 Mystere
 * Second version with increased power. Acceptable power range 100 to 160 hp, with the standard engine a Lycoming O-320 of 150 hp. Kit price in 2003, without engine, was US$27,900. Only one prototype was flown.


 * S45 Mystere Mark II
 * Third version with aerodynamic refinements, an increase in top speed to 180 mph and an increase in gross weight to 1925 lb. The engine was raised so that the aircraft could accept a larger diameter propeller and to increase clearance between the tail boom and the propeller. The engine cowling was also re-shaped to smooth airflow into the propeller. These changes were all to reduce the original S45's noise signature. Kit price in 2003, without engine, was US$27,900. Only one prototype was flown and it was the original S45 prototype in a modified Mark II configuration.


 * S45 Mark III RG
 * A proposed retractable gear model that was never built. The Mark III was announced by the company in 2003, with a first flight initially forecast for 2004. It was intended to have a shorter wing and accept engines up to 250 hp to greatly increase cruise speed.

Accidents and incidents
The prototype Partenair S44 Mystère was involved in a fatal accident on 24 October 1998. While departing Montréal/Les Cèdres Airport, the Rotax 912 engine failed and the aircraft impacted the ground, killing both occupants.

This accident led to the aircraft being redesigned as the S45 with a Lycoming O-320 engine replacing the Rotax powerplant. Kitplanes magazine described the subsequent S45 as a "repowered aircraft for better overall performance and reliability".