The GWS F-3A Formosa or simply GWS Formosa is a foam ARF electric park flyer manufactured and distributed by Taiwanese hobby manufacturer Grand Wing Servo-Tech. The model is patterned after large-scale "F3A" pattern planes and offers good aerobatic potential. As such, the Formosa is intended for use by intermediate to advanced pilots experienced with aileron control.
As with many GWS kits, the Formosa comes as two fuselage halves, a one-piece wing, fiberglass wing reinforcement spar, horizontal stabilizer, hardware, vacuum-formed cowl, decal sheet and on later kits, a canopy with a separate vacuum-molded plastic shell and revised clip-on canopy mounting system with a separate addendum to the assembly manual. The original magnetic latch parts are included as well. All airframe parts are made from fine-beaded EPS foam. The control surfaces need to be cut out from the wing and stabilizers and then beveled and hinged; the model's low parts count means very little construction. A detailed, full-color assembly manual in both English and Chinese is included.
Three versions of the Formosa are offered and the hardware package varies accordingly:
- GW/FORMOSA-EPS350C which includes a GWS EPS-350C gearbox with brushed motor
- GWAEO015 "NPS," or "no power system." Identical to the above version less the gearbox and motor
- GW/FORMOSA-SG "slope soarer" glider with no power system or landing gear. The EPS-350C gearbox frame and propeller shaft are included to enable a spinner to be installed and to assist in balancing the model
A GWS 11.1v 1050mAh nickel metal hydride battery pack is recommended for use with the EPS-350C power system and to power the radio system in the slope soarer version.
Center of gravity is listed at 90mm +/- 10mm behid the leading edge of the wing, or approximately on the reinforcement spar. Since the Formosa is neutrally stable, it will fly inverted with no trim change when the CG is an additional 5mm behind the spar.
When properly balanced, the Formosa flies well when under the control of experienced pilots. The low-wing configuration will not recover on its own, making the model unsuitable as an aileron trainer. R/C pilots with previous aileron experience may find the Formosa to be ideal for practicing basic aerobatics. Its small size and light weight make it somewhat susceptible to wind; this can be overcome to some degree with a more powerful propulsion system. The stock propulsion system tends to be rather underpowered, so it is recommended to either upgrade an existing model or assemble a new one with brushless power.
The stall is gentle and spin recovery is simple.
The stock landing gear may be too small for use on grass but the Formosa is easy to hand launch. Landings can tend to "float" since the model is also designed as a glider. It is not, however, designed for 3D aerobatics.
Virtually any basic aerobatic maneuver or pattern including knife edge flight can be accomplished depending on the power setup.
The EPS foam airframe is prone to "hangar rash" but is quite good at absorbing the shock of bad landings. It is also far more brittle than the more flexible and durable EPP foam used in newer models, especially those from Multiplex and, as of late, ParkZone and HobbyZone. Most crashes can usually be remedied with the same two-part epoxy and foam-safe CA used in the initial assembly, but the model's low cost makes rekitting an attractive alternative to rebuilding after a major crash and flying a so-called "glue bomb."
The thin, vacuum-formed motor cowl is especially susceptible to damage in even the smallest of crashes, but it and any other part are available through any hobby dealer which stocks GWS models and accessories.
As mentioned earlier, the stock brushed motor/gearbox combination is somewhat underpowered and it's well worth upgrading to (or starting from scratch with) a brushless motor. Almost any system with an output of 100W or more will greatly improve performance. A brushless motor rated at around 1300Kv will work very well with a 3s battery. A suitable lithium polymer battery should be in the range of 1500mAh for a three-cell pack or 2000mAh for a two-cell. Any more power and weight may require extra structural stiffening.
If one is assembling a new Formosa with upgraded power in mind, modifying the battery compartment area of the fuselage halves is best accomplished before the two halves are epoxied together.
The single servo and torque rods work reasonably well, but given the price of modern servos, a two servo wing is more precise and allows you to use spoilerons to shorten the approach.
Specifications and factory-recommended requirements
- Length: 912mm (35.9 in)
- Wingspan: 900mm (35.4 in)
- Wing area: 16.5dm² (255.8 sq in)
- Empty weight: 340g (12 oz)
- Flying weight: 410g (14.5 oz)
- Wing loading: 24.8g /dm² (8.1oz/sq.ft)
- Power system: GWS EPS-350C/DS
- Propeller: GWS EP1147
- Battery: Seven-cell 1050mAh nickel metal hydride
- Servos: GWS "PICO" or "NARO" series; Hitec HS-55 micro-servo works very well as an aileron servo
- Electronic speed control: GWS ICS-300
- Radio system: Four- or more channel aircraft system