This item is discontinued.

GREAT PLANES F4U CORSAIR ARF
PRODUCT REVIEW
By Bob Wallace

Great Planes "ARF" (Almost Ready to Fly) F4U Corsair is a sport-scale design that is intended to be powered by a .46-.52 cu. in. 2-stroke or.70-.80 cu. in. 4-stroke engine. Any 4 or 5-channel radio system with standard size airborne components may be utilized.

The Great Planes (ARF) F4U Corsair is neatly packaged in a sturdy 11" x 12" x 36", compartmentalized, corrugated carton that is covered on all four sides and the top, with attractive, highly visible, full-color labeling that shows numerous views of the model, accessories, and kit information.

The pre-finished kit components are carefully packaged in vinyl bags, as are the various subassembly parts and accessories.

As this is an ARF kit, no plan sheet is included, nor is one required. A 31-page (8-1/2" x 11") instruction manual that includes numerous assembly photographs and line drawings is included. This manual truly is an "instruction" manual, as it covers far more than just the assembly steps for this model. Each sequential assembly step is accompanied by a clear photograph of that particular phase of assembly. The installation of the fuel tank, engine, radio components, etc., are included, along with the final balancing and test flying information. While the manual is not perfect, it is clearly evident that a lot of time and effort went into its preparation.

The fuselage unit is comprised of a conventional inner, die-cut lite ply and balsa structure that is skinned with balsa sheeting. A thin foam layer that has a bonded, pre-finished plastic outer skin has been applied to the balsa sheeting. The plywood firewall bulkhead has been painted with a black fool-proof coating. A molded cockpit with a pilot upper torso has already been installed. The Corsair builder may paint this area to suit and then glue the pilot "head" and clear plastic canopy in place. The inner (elevator and rudder) control rod sleeves are also installed. The tail surfaces are of balsa inner construction, with a pre-finished plastic sheet outer surface. The stabilizer/elevator assembly has the control horn and hinges permanently installed. The two outer wing panels are of traditional built- up balsa rib and spar construction, covered with the same type of foam, pre-finished plastic sheet material that is used on the fuselage. The inner, inverted gull wing segment of the wing is also of conventional built-up balsa and this plywood construction, except that this wing portion features molded pre-finished plastic outer skin pieces that are applied after the landing gear units (either fixed or retractable) have been installed. The two pre-finished outer wing panels are joined to the center section.

Replacement parts for all of the pre-finished subassemblies are available, should the need ever arise.

This aircraft may be assembled with either fixed or retractable landing gear and the kit includes all of the necessary parts for a fixed landing gear installation.

A sheet of cleanly cut die-cut plywood parts is included and the engine cowl consists of four plastic parts. The hardware and accessory packages are very complete and it is easier to list the additional items required rather than what is included.

Other than the radio system, engine, and usual adhesives, all that is required is a "Pitts" style muffler for the engine and an optional fuel filler valve which simplifies the fueling process. If retracts are to be employed, the builder must provide these, along with the related hardware and retract servo.

A preliminary inventory of the kit parts and various subassemblies revealed that the molded plastic fuselage tail cone was missing. Oddly enough, this part does not appear to be shown in the part's list photo in the instruction manual.

For additional scale realism, a large sheet of pressure-sensitive decals is also included in the kit.

Assembly:

The assembly process starts with the installation of the installation of the aileron servo and tray within the wing center section. At this point of assembly, the builder must decide if fixed landing gear or a retract system is to be used. As mentioned, all of the necessary components for a fixed landing gear installation are included in the kit. For our product test review Great Planes also provided a set of Hobbico 90 retracts, which are perfectly matched to fit the Corsair. The installation of the retracts and related linkages is the most involved step in the Corsair's assembly, however, the instruction manual is very systematic and clear in explaining and illustrating this phase of assembly.

While the instruction manual appears to have been prepared in this country, this kit is actually made in Taiwan.

Assembly commences with the installation of the retractable landing gear units, aileron and retract servos, and related linkages, which fit nicely into the center section assembly. The pre-finished outer wing panels are joined to the center section assembly with pre-cut plywood dihedral braces which are epoxied in place.

After the aileron linkages, wing bolt-mounting block, and dowel have been installed, the wing is mounted to the fuselage and the center section molded plastic cover pieces are installed. The fit of the top and bottom molded plastic surfaces was only fair.

The pre-finished tail surfaces and coupled tail wheel assembly are then installed, along with the radio system components and other operating equipment. A 320 cc (a little less than 11 oz.) fuel tank is provided along with an adjustable filled nylon engine mount and these units fit perfectly into place. All of the necessary control linkage hardware is included.

The molded plastic cockpit area features a partial pilot bust and instrument panel. This area can be painted to suit the builder's preference before the molded clear plastic canopy is glued in place. The canopy fit to the fuselage was very good.

The fuselage unit in our kit had a few small areas where excess CA glue had been smeared onto the plastic outer finish during the factory assembly process. It was not possible to remove this excess CA with debonder, as a small sample test revealed that the CA debonder solvent would also remove the finished surface of the aircraft.

The molded plastic engine cowl consists of four ABS plastic pieces that must be glued together. For added realism, radial engine cylinders have been molded into the front portion of the cowl. A Du-Bro Kwik-Fill valve was installed on the cowl of our Corsair to simplify the fueling process. Satellite City "Hot Stuff" CA adhesives and Great Planes 6 and 30-minute epoxies were used in assembling our Corsair.

Engine:

In the instruction manual, Great Planes states that if a .46 (2-stroke) engine is to be used, it should only be a high performance type, and that for even higher performance, a .6 1-size engine may be employed. I elected to use an old, but reliable K&B .61 engine that was equipped with a Slimline "Pitts" style muffler. The Corsair cowl is large enough to accept a .61-size engine without the need to cut any opening, other than for access to the glow plug. The use of a larger.61 -size engine also allows a larger 12" propeller to be used, which looks a little more in proportion and is more effective.

It should be noted that with the use of any 2-stroke engine, that its stock manufacturer-supplied muffler cannot be used without making major modifications to the Corsair's fuselage. A "Pitts" style muffler is required.

A .70-.80 4-stroke engine would also appear to be an excellent power choice for the Corsair, as this would allow an even larger diameter prop to be used, plus it would aid in achieving the proper C.G. (more on this later). A Tru-Tum propeller hub nut assembly was also used on our Corsair for added scale fidelity, and a Master Airscrew 12 x 6 was to be used for our initial test flights.

Radio:

An Airtronics Stylus radio system was used to guide our Corsair. The airborne pack consisted of an Airtronics #92765 FM standard size receiver, four #94102 standard servos, a #94734 retract servo, and a #95004 600 mAh battery pack.

The Corsair's fuselage and wing center section area is large enough to easily accept any normal size radio components. All of the radio components in our Corsair were installed in the locations provided, or indicated, in the instruction manual. The manual also provides recommended control surface travel limits, both for high and low rates, and our Corsair was set up according to these limits.

A Great Planes C.G. Machine was used in determining the C.G. of our completed Corsair and it was found to be far to the rear of the recommended point. Twelve ounces of lead, attached to the firewall, was necessary in order to correct the pronounced tail heavy condition and achieve the proper C.G.

Our ready-to-fly (less fuel) Corsair weighed 8 lbs. 2 oz. (129 oz.). This was a bit surprising considering that 12 oz. of lead had been added to the nose, in order to balance the model, and it was still almost 4 oz. lighter than Great Planes' advertised weight for this aircraft of 8.3 pounds (132.6 oz.).

Great Planes claims that this kit can be completely assembled in about 20 to 25 hours and this is an accurate estimate.

Flying:

A beautiful late autumn day, with sunny skies, high 40's temperatures, and only a slight breeze ("that's beautiful for late autumn in New England") was the setting for our initial test flights.

The site for our maiden test flights was a well-maintained, level turf farm, and the grass had been cut fairly low.

After the usual radio system range check, the K&B .61 engine was started and adjusted to produce a slightly rich full-throttle setting and a proper idle.

A minute or two were then spent attempting to perform taxi tests in order to evaluate the Corsair's ground handling characteristics. This proved to be a rather frustrating experience, as the Corsair demonstrated a pronounced tendency to go up on its nose. Holding full "up" elevator on high rate, helped as long as the Corsair was taxied at a brisk speed. However, at slow taxi speeds, this was of little help.

In this reviewer's opinion, the problems encountered in taxiing on grass were due to the size of the Corsair's wheels. They are 58 mm or 2-5/16" in diameter which, for a tail-dragger of this size and weight, are rather small. It is not possible to simply replace these wheels with larger diameter units, as the wheel wells that are molded into the ABS plastic bottom wing panel covering are not large enough to accept them when the landing gear is retracted. Our Corsair was then headed into the wind and full throttle was gently applied. Several feet into the take-off run, the Corsair went up on its nose again. On the second take-off attempt, the Corsair was released at full throttle, holding full "up" elevator at a slight amount of right rudder. As soon as the Corsair had attained a brisk take- off speed, the elevator was neutralized, while continuing to hold a bit of right rudder in order to keep the Corsair tracking on a straight heading. As our Corsair had a fairly high wing loading (30.9 oz./sq.ft.), no "up" elevator was applied until a fairly high take-off run speed had been attained. This took approximately 100 feet and only a small input of "up" elevator had our Corsair airborne and climbing out at a nice shallow angle.

The landing gear was then retracted and a few clicks of up elevator and right aileron had our Corsair flying thumbs off, straight and level. The next several minutes were spent performing a variety of maneuvers, both at high and low rates. The manufacturer's suggested control surface travel limits were found to be ideal. On low rates, the Corsair was smooth and subdued, while on high rates, it was surprisingly nimble.

A series of stalls were then performed, with no tendency to snap roll or drop off into a spin, being evident. When the stall occurred, our Corsair would simply drop its nose a bit and settle until adequate flying speed had been regained. The Corsair's slow flight characteristics were found to be quite good, especially so for an aircraft with its fairly high wing loading. Several high-speed, low-level flybys were then performed and this is where the Corsair really looks great!

The K&B.61 engine, with a 12 x 6 Master Airscrew prop, proved to be ideally suited for use with the Corsair.

A few slow speed landing approaches, with the landing gear extended, were made in preparation for our first landing, which was then made in the following manner: about 1/4 to 1/3 throttle was held, while maintaining a brisk airspeed throughout the entire landing approach. When the Corsair was on final approach and several feet above the grass landing surface, the throttle was then closed to idle and as the air speed bled off, increasing "up" elevator was applied, and the aircraft settled in for a very nice, three-point landing. As the Corsair neared the end of its landing rollout, it went up on its nose in spite of full "up" elevator being held.

Two additional flights were then made using the same take-off technique and landing procedure. On every landing rollout, the Corsair came to a stop by going up on its nose. However, no damage was sustained.

This was not the case on our fourth flight when, upon landing, the right landing gear unit was tom from the wing during the landing rollout. The landing was not a hard one and the failure occurred toward the end of the rollout.

The landing gear units are mounted onto a 2.5 mm plywood plate that has a 2.5 mm plywood doubler plate. This plate, like all of the other plywood parts in the Corsair, is of the wood type that is commonly used in many imported kits. It is comprised of two very thin outer face veneers with only a soft, pulpy inner core.

When assembling our Corsair, the temptation certainly existed to reinforce or replace these mounting plates with plates made of higher quality aircraft grade plywood. However, that would have been defeating the purpose of an objective review as the aircraft should be evaluated according to how it has been factory assembled and/or to the manufacturer's recommended assembly instructions.

While the factory installed landing gear plates may be acceptable for flying from smooth paved runways, in this reviewer's opinion, they are not strong enough to ensure trouble-free flying from grass fields.

The combination of small diameter wheels with the weak landing gear mounting plates is the Corsair s most serious shortcoming. While the use of fixed landing gear legs would allow larger diameter wheels to be used and would probably solve the grass field take- off problem, the potential for an eventual landing gear mount structural failure would remain.

The Corsair looks a lot nicer in flight with the landing gear retracted, than it would with a fixed gear installation. However, anyone purchasing this kit must decide for themselves whether the simplicity and lower cost of a fixed gear installation outweighs the more pleasing visual appearance of a retract equipped version.

After the damaged landing gear unit had been repaired and reinstalled, our Corsair was taken to a paved parking area a few days later in order to evaluate its taxiing capabilities on t at type of surface. While it could not be flown from that area, the Corsair did demonstrate good ground-handling characteristics.

In summary, Great Planes ARF F4U Corsair is a kit that should appeal most to those modelers who do not have the time, desire, or interest in building a conventional stand-off or sport-scale version of this popular World War II fighter, yet wish to own and fly such an aircraft.

While it could be powered with a high performance type .46 size 2-stroke engine, this reviewer believes that a .61 size 2-stroke sport type engine or a .70 to .91 size 4-stroke is a better choice. It also allows a larger diameter and more scale size prop to be used. No matter what size engine is employed, it is a certainty that a significant amount of lead will have to be added to the nose in order to obtain the proper C.G.

In spite of its shortcomings, Great Planes (ARF) F4U Corsair has a nice stand-off scale appearance and does fly very well. RC'ers who fly from grass fields can expect to encounter problems with the landing gear, be it fixed or retractable, unless those areas are reinforced. Those with access to a paved runway will be far more pleased with this aircraft. It is not intended for beginners and Great Planes states this in the instruction manual.