Fauvel AV.36 / AV.45

M.Hardy. Gliders & Sailplanes of the world

Fauvel AV 361 France

  The tailless sailplane, because it embodied the designer's dream of the flying wing as a purely aerodynamic surface providing lift but devoid (or almost so) of drag-producing excrescences such as a fuselage, had for long been an interesting avenue of development. In Germany before the war both Dr Alexander Lippisch and the Horten brothers had built and flown several tailless gliders in their search for the ultimate in performance that culminated in the rocket-powered Me 163, and the Westland-Hill Pterodactyls and Northrop flying wing designs likewise had military applications. In France Charles Fauvel has been developing tailless sailplanes for many years, his original AV 36 Monobloc single-seater having first flown in 1951, and over 100 were sold to customers in 14 countries, many in kit form for amateur construction, before the Monobloc was succeeded by the improved AV 36 Mk II, officially designated AV 361, which first flew in 1960. This sales record showed that the problems of stability and control so often associated with tailless aircraft could be avoided by sound design, as could unpleasant handling characteristics. Well over 100 AV 36s and AV 361s are now flying in 17 countries and construction by amateurs continues, especially in the USA and Spain; plans are now available in French and English, and 50 AV 36s were also built by Wassmer-Aviation SA. A recent bonus is that customers can now choose a laminar flow Wortmann FX-66-H-159 wing section instead of the non-laminar F2 section of 17% thickness/chord ratio used hitherto; this increases the best glide ratio to 30:1 at 53mph. The AV 361 is suitable for competition flying or training, and can be flown safely in cloud; its span has been increased to 41ft 10 1/2 in from the AV 36's 39ft 2 1/2 in, and it has redesigned fins and rudders, as well as larger ailerons than the AV 36. The cantilever shoulder wing is of fabric-covered wooden construction and has no sweep-back because, in a tailless sailplane, the problem of cg range can be neglected since there is no changing load to cater for, and the wing can be designed to obtain the lowest value of induced drag. The elevators are in the trailing edge of the wing centre section, since there is no tailplane, the fins and rudders being carried on two short stub-like fairings projecting from the wing; the rudders can be folded forward to reduce overall length for transportation on a trailer. There are Schempp-Hirth retractable air brakes above and below each outer wing, and there is a large trim tab in the port elevator. The fuselage is a short nacelle of wooden construction, with the pilot seated under a sideways-opening blown Plexiglas canopy; there is provision for oxygen and radio. The nose can be hinged upwards to reduce length when the aircraft is transported sideways on a trailer. The landing gear consists of a flexible rubber-sprung skid, although a monowheel and rear skid can be fitted as an alternative, and there are curved wire 'bumpers' under the wing tips. In February 1971 Mons Fauvel decided to cease commercial production of his sailplanes, but plans for the AV 361 and other designs are still available for construction by gliding clubs or homebuilders.

Data: AV 361
Span: 41 ft 10 1/2 in
Length: 10 ft 8 in
Length: 8 ft 1 in (folded)
Wing area: 157.2 sqft
Aspect ratio: 11.4
Empty weight: 269 lb
Max weight: 569 lb
Max speed: 137 mph (in smooth air)
Min sinking speed: 2.5 ft/sec
Best glide ratio: 30:1 at 53 mph (laminar flow section)

Fauvel AV 45

  This single-seat tailless self-launching motor glider was developed from the AV 36 and AV 361 sailplanes, and first flew in prototype form on 4 May 1960, powered by a 35hp Nelson four-cylinder two-cycle engine in a pusher installation driving a two-blade propeller. Later a 45hp Nelson engine was fitted, and in the summer of 1967 the prototype was re-engined with a 150lb st Microturbo Eclair 012-01 turbojet based on the turbo-starter used for the Olympus engines of the Concorde SST prototypes; this was mounted in the same position as the Nelson engine, with the long jet pipe exhausting over the wing trailing edge. In this form the prototype was redesignated AV 45-01R and the Eclair gave it an outstanding performance despite the heavier powerplant and the necessary fire protection; maximum level speed was now 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 tandem two-seater AV 46 and the single-seater AV 48, which were originally designed to have the 40hp Fauvel Pygmee 'flat four' four-stroke, as was the production AV 45. The prototype has now been fitted with a 30hp Rockwell-JLO engine by another amateur builder. Meanwhile, a second slightly modified prototype had flown which had been built by Societe Aeronautique Normande and had a 22hp Hirth Solo 'flat four' two-stroke engine. This 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 3.5in, 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.
  The standard engine recommended for production aircraft is now the 40-55hp modified Hirth O-280R 'flat four', there being integral wooden fuel tanks in the wing leading edges. A French homebuilt AV 45 is flying with a Nelson engine, and a Japanese homebuilt one with Hirth Solo engine is flying in South Africa; in early 1978 11 more AV 45s 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 now be fitted with a wing of Wortmann laminar flow section, which gives an improved best glide ratio of 30:1. The AV 451 is an improved version of the AV 45, also with a laminar flow wing of Wortmann FX-66-H-159 section and the span increased to 15m (49ft 2 1/2 in). The nose is more tapered, the wheel fairings more streamlined, and the vertical tail surfaces are of Wortmann symmetrical section. 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 AV 45 F-CCRM with the 15m wing span and new Wortmann wing section of the AV 451, 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 was due to make its first flight in mid-1978 and is expected to have a best glide ratio of 32:1 at 54mph with the propeller folded and stowed.
  The cantilever shoulder wings are of F2 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.

Data: 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

Jane's Encyclopedia of Aviation

Fauvel AV.361, AV.45/AV.451 and AV.222 (France)
Single-seat general-purpose sailplane, single-seat tailless motor glider and two-seat motor glider respectively, plans of which are available to amateur constructors.