The RF - 4 achieved many extremely unusual performances, including various long-distance flights. Probably the best known of these was the Atlantic crossing in 1968, carried out by the exiled Czech pilot Miro Slovak. Subsequently he also succeeded in crossing the American continent, arriving in Santa Paula in California.
Our model is designed to 1:4 scale, as this size makes it possible to accommodate both a retractable undercarriage and airbrakes. It is designed primarily for the range of four-stroke motors: the single-cylinder Saito FA-56, 65, 72, 80 and 91, and the FA 90 TS and FA 100 T opposed twins. For any single-cylinder motor is recommended to use vibration-damping motor mount. Alternatively an electric power system can also be installed, e.g. the actro 24-5 with a CAM 14 x 8” or 14 x 9” propeller and 16 cells. In flying terms our RF - 4D is a connoisseur’s delight. The wing features both aerodynamic and geometric washout, and in conjunction with an extremely low wing loading this endows the model with excellent, beautifully balanced flying characteristics. It deserves to be flown in true “scale” style, as this looks wonderful and helps to avoid heart trouble! The Fournier is a picture of elegance in the air, especially at low altitude, and can be flown over a broad speed range from leisurely to quite fast.
Moderate “classic” aerobatics are possible: loops, impressive stall-turns, rolls and similar manoeuvres present absolutely no problem provided that you keep the model’s layout in mind. Fuel consumption is minimal, as most of the time the machine is flown with the motor throttled back. Long landing approaches are the order of the day, but the airbrakes provide accurate control of the glide path. The Fournier features separate wing panels joined by an 18 mm Ø dural tube of extremely high strength; the tailplane is designed to be glued permanently to the fuselage (mounted on carbon tubes).
Access to the RC system is excellent through an extremely generous opening in the underside of the fuselage. The same opening also provides access to the wing retainer system. The GRP fuselage is of the high quality expected of aero-naut products, and includes integral root fairings for the wing and tailplane panels, integral fin, pushrod fairings etc. The horizontally split two-part GRP motor cowl features integral locating pieces for accurate joining. The cockpit fittings supplied in the kit are based on the full-size machine, and take the form of ABS plastic mouldings.
The building instructions provide additional notes on fitting out the cockpit (e.g. padding). The sprung retract unit with its 95 mm Ø air-filled wheel was specially developed for this model. The dural and steel metal parts are accurately formed by a computer-controlled water jet cutter, various joints are hard-soldered and the surfaces are powder-coated.
The wheel retracts into an ABS mudguard which is built into the fuselage. A pneumatic retract actuator with an 18 mm Ø bore pressure cylinder provides the retraction force, and is designed as a single-action system. This is an important contribution to safety, as the wheel automatically extends if there is a pressure loss in the system.. The retract system also includes a variable pressure reducer, enabling you to adjust the rate of retraction / extension to a “scale” speed. The control valve is also a single-action unit, actuated by pressure from a curved disc (cam) mounted on a (mini-) servo or similar; a coil spring provides the extension force. The only item you need to purchase separately as a hand-pump with manometer.
We strongly recommend that you install the motor using our rubber buffers. The flight battery should take the form of two packs (2 x 8 cells). The packs must be installed projecting into the motor compartment (cowl) in order to obtain the correct C.G. (balance point).
An appropriate engine sound is an important factor in the full experience of flying any powered model aircraft. Certainly with scale models a completely non-scale sound should be avoided, otherwise the overall image is spoiled. In short - the RF-4D deserves a four-stroke motor. We recommend the use of motor mount with rubber buffers, which will accept all the recommended single-cylinder motors. This mount reduces the transmission of motor vibration to the airframe, and thereby reduces the noise emitted by the airframe itself.
The 9.1 cc Saito FA-56 provides plenty of power for realistic scale flying, but any Saito motor from the FA-56 to the 15 cc FA 91S will fit. Of course, the perfect choice would be an opposed twin such as the 15 cc Saito FA-90TS or the 16.4 cc FA-100T.
To increase power system reliability we recommend that you fit an on-board glowplug regulator; there are plenty available commercially. These units also offer an additional advantage: they eliminate the need for a separate glowplug battery for starting, together with the ugly hole for the plug clip.
Incidentally - all the motors mentioned above disappear completely under the cowl.
- Motor control
- GRP fuselage
- GRP motor cowl
- Wing set
- Elevator / Rudder set
- Retractable wheels