Fournier RF-4D, Span 2815mm, GRP fuselage/finished wing
Aeronaut # 135500

The model was designed in 1:4 scale so that retractable landing gear and airbrakes could be installed. Four-stroke engines are primarily intended as propulsion - single-cylinder Saito FA-56, 65, 72, 80 and 91 or boxer engines FA 90 TS and FA 100 T.
The installation of an electric drive is also possible.
Aviation-wise, the RF-4D is a treat. The wing has both aerodynamic and geometric washout, which, in conjunction with a fairly low wing loading, ensures excellent, balanced flight characteristics.
It deserves to be flown "scale", for the eye and the heart!
Radiant elegance, especially at lower altitudes, flying style - leisurely to quite brisk. Moderate "classic" aerobatics are possible. Loops flown with feeling, effective turns, rolls or similar are no problem.
Since most of the time is flown with a throttled engine, fuel consumption is minimal. Long approaches can be precisely managed with the help of the airbrakes.

The wing is two-part, the 18mm connection forms a Duralumin tube of the highest strength, the horizontal stabilizer is firmly glued to the fuselage (via carbon tubes).
Access to the RC equipment is ensured by a fairly large cutout on the fuselage bottom. The wing locking mechanism is also accessible here.
The GRP fuselage is of the high quality usual for aero-naut, with molded root ribs for wings and horizontal stabilizer, fin already molded, all necessary openings as well.
The horizontally divided, two-part GRP cowl already has guides for centering both parts.
The cockpit interior is based on the original, these parts are made of ABS plastic. The building instructions provide further tips on how to design the interior (e.g. upholstery).
The retractable landing gear, sprung, with hollow rubber tires of 95mm diameter was specially developed for this model. The sheet metal parts made of Duralumin or steel are precisely manufactured by computer-controlled water jet, various places hard-soldered and powder-coated.
It retracts into an ABS fender built into the fuselage.
Pneumatic retractable landing gear control with its 18mm diameter air cylinder (bore) is designed as single-acting. This is an important contribution to safety, as the landing gear automatically extends in the event of a pressure loss in the system!
Included in the delivery is an adjustable pressure reducer, with which the time sequence of retraction or extension can be set "scale". The control valve is also designed as single-acting, actuation is done by pressing a cam (lobe) mounted on, for example, a (mini) servo, extension is provided by a coil spring.
Only the hand pump with manometer (e.g. Robart) has to be purchased separately.

The model kit contains:

• Detailed building instructions with construction stage photos
• Blueprint with RC installation
• GRP fuselage and cowl
• Wings in Styro-Abachi, horizontal stabilizer in Styro-Balsa construction
• Airbrakes, spinner, retractable landing gear and outrigger landing gear, tail skid, exhaust and filling support dummies
• Canopy, ABS parts, CNC milled parts from plywood and GRP, stamped parts
• Duralumin tube diameter 18 / 16mm GRP tube (connection guide)
• Wing locking mechanism
• Identification of the prototype - plotted, with transfer film
• Set of small parts

Motorization:

Due to the favorable aerodynamic design, especially wing loading and high aspect ratio, the RF-4D is ideally suited for electric propulsion.
An engine sound is also part of an engine-powered aircraft, part of the flight experience. In a scale model, the sound should also be scale, so that the flight picture appears balanced. In short, the RF-4D needs a four-stroke engine.
Even with the Saito FA-56 with 9.1 ccm, the model is well, scale motorized. All Saito FA 56 up to the FA 91S with 15 ccm can be installed. Of course, boxer engines Saito FA-90TS with 15 ccm and the FA-100T with 16.4 ccm are best suited.
To increase the safety of flight operations, the installation of a glow plug driver is recommended; the market offers a large selection. Another advantage: the starting battery is not required (and the ugly hole for the glow plug).
By the way - all mentioned engines disappear completely under the cowl!