Fauvel AV.45 / AV.451
Inspired by two previous German experiences of motorizing the AV-36, and greatly motivated by the concept of the motorglider, Charles Fauvel flew the new AV-45 on May 4, 1960, an AV-36 very modified and powered by a pusher Nelson motor of 37 hp driving a two blade propeller. Later a 45hp Nelson engine was fitted. The second improved prototype, built by the SAN (Société Aéronautique Normande) in Bernay, took off with Charles Fauvel in command in 1962. This copy was equipped with a Solo engine of 23 hp that permitted, in spite of its low power output, enough power to take off in less than 100 ms and to climb at up to 3 m/sec.
This second prototype was representative of production AV 45s, which are intended for amateur construction, and it incorporated several changes, including the introduction of additional windows under the cockpit canopy, moving the pilot's seat 2.4in further forward, lengthening the fuselage by 3.5 in, and fitting larger vertical tail surfaces carrying at the bottom small steerable skids which replace the underwing curved wire 'bumpers' of the first prototype. Hoerner wing tips were also successfully tried on the AV 45, and the original two-blade fixed-pitch airscrew was later replaced by an automatically feathering prop.
Microturbo was anxious to test this 78 Kp turbojet on a glider and Fauvel made available AV45 # 1. In 1967, the Nelson H 59A motor was replaced by a Microturbo Eclair 012-01 turbojet of 68 Kg / 150 lb of thrust in the summer of 1967. It was equipped with an electric starter and battery (NiCd 9.5 kg) for a self-starting it (both in the ground and in the air). The installation was characterized by the need to have a very long nozzle to allow ejection of the jet behind the fuselage.
Fauvel AV45-01R Microturbo Éclair
The first flight was by Charles Fauvel, and the second he was joined by Jacques Hemet Stampe as a photographer filming the event. In this form the prototype was redesignated AV 45-01R and the Eclair gave it a maximum level speed of over 140mph at 2,625ft and the maximum rate of climb 990ft/min, the time to 10,000ft being 15min. The Eclair's battery permitted repeated restarts in flight as well as ground starting, and this turbojet was also seen as a possible powerplant for two other Fauvel tailless powered glider projects.
The prohibitive price of this jet engine did not allow its use for practical reasons. The prototype was later fitted with a 30hp Rockwell-JLO engine by an amateur builder. The standard engine recommended for production aircraft is the 40-55hp modified Hirth 0-280R 'flat four', there being integral wooden fuel tanks in the wing leading edges.
The first AV-45 motorglider of amateur construction, equipped with a Solo engine, was constructed in Japan and flew in South Africa (with Hirth Solo engine), while several copies were begun in the United States, in Finland, Germany and Spain. A French homebuilt AV 45 was flying with a Nelson engine. In France alone, even though some copies were constructed by amateurs, most glider pilots remained for the most part unconvinced of the charms of this motorglider. In early 1978 11 more AV45s were being built by amateur constructors, four in France, three in the USA, and one each in Finland, Germany, Martinique and Spain, the German one having a Solo engine. Like the AV 361, the AV 45 can be fitted with a wing of Wortmann laminar flow section, which gives an improved best glide ratio of 30:1.
Not discouraged, Charles Fauvel further improved the motorglider with the AV-451 version. This ship had its span extended to 15 m (49ft 2.5 in), incorporated a new airfoil design from Wortmann : the Laminar FX 66-H 159, a new fuselage shape obtained by using an existing glass canopy design (the one on the Grob Astir glider). The nose is more tapered, the wheel fairings more streamlined, and the vertical tail surfaces are of Wortmann symmetrical section. The propeller was automatically folded rearward by airflow effect when the engine was stopped.
The Gross (Fauvel) AV 451, actually the first AV 451, was designed and built by Mons Francois Gross with his son's help and is a modification of AV45 F-CCRM with the 15m wing span and new Wortmann wing section of the AV451, a longer fuselage modified in the cockpit area to take the canopy from a Grob Astir, and with a 38hp Rotax 642 two-cylinder two-stroke engine aft of the cockpit, driving a two-blade Hoffmann pusher propeller. It made its first flight in the beginning of September 1978. The cantilever shoulder wings are of Fz 17% thickness/chord ratio section or Wortmann profile, with no dihedral on the centre section and 5° 13' on the outer wings. The wings are single-spar wooden structures, with a plywood leading edge torsion box and fabric covering aft of the spar; there are conventional ailerons and the elevators are in the trailing edge of the centre wing, with a large trim tab in the port one.
Schempp-Hirth air brakes are fitted in the upper and lower surfaces of each outer wing, just outboard of the fins. The fuselage consists of a short wooden nacelle with glassfibre covering, the pilot sitting under a sideways-hinged blown plastic canopy. The wooden twin fins and rudders are inset at the junctions of the centre section and the outer wings, there being no tailplane; the fins are plywood-covered and the rudders fabric-covered. The undercarriage consists of two wheels in tandem, a steerable front wheel and a rear wheel with mechanical brake, supplemented by small steerable skids at the bottom of the vertical tail surfaces. Endowed with a L/D of 32:1, the AV-451 was the last flying wing of Fauvel. An entirely fibreglas composite version (AV-48) had been considered, but a fire at the shop where the prototype was to be constructed put an end to this adventure.
The death of Charles Fauvel explains in part the fact that the AV-451 didn't attain the success of the AV-36 and AV-361.
AV 45 second prototype
Span: 45 ft 1 in
Length: 11 ft 9 in
Height: 6 ft 0 in
Wing area: 171.7 sqft
Aspect ratio: 11.84
Empty weight: 476 lb
Max weight: 772 lb
Economical cruising speed: 80 mph
Min sinking speed: 2.62 ft/sec at 43.5 mph
Best glide ratio: 27:1 at 53 mph
Rate of climb at sea level: 550 ft/min
Take-off run: 492 ft
Wing span: 13.75 m
Length: 3.6 m
Wing area: 14.80 sq.m
Airfoil: Fauvel F4 17%
Aspect ratio: 10.8
Empty weight: 219 kg
Maximum gross weight: 350 kg
Glide ratio: 26:1
Min sink rate: 0.82 m/sec
Engine: Microturbo Éclair, 68 kg thrust
Best glide: 29 @ 85 Km / h
Min rate of descent: 0.78 m / s
Performances tinkering usage provisioning engine
Rate of climb: 240 m / min @ 120 Km / h
Maximum speed (800 m): 225 km / h
Time to 3000 m: 15 min
Fuel capacity: 31 lt
Endurance: 22 min
Wing span: 15.0 m
Length: 3.84 m
Wing area: 16.68 sq.m
Airfoil: Wortmann FX-66 H 159
Aspect ratio: 13.5
Empty weight: 250 kg
Maximum gross weight: 380 kg
Glide ratio: 32:1
Min sink rate: 0.72 m/sec