Yellow aircraft: F/A-18 Hornet

Model Airplane News, Sep 2000 by Boswell, Bob

Impressive 1/10-scale Navy fighter

With the Yellow Aircraft* F/A-18 Hornet ducted-fan kit, you can reproduce one of the Navy's most advanced fighters as accurately as possible. Yellow Aircraft's goal is to build high-quality scale aircraft with much of the labor-intensive steps and detailing already completed, so that construction time is minimal and the modeler can be flying in a reasonably short time. The Hornet is testimony to this effort, as the fiberglass fuselage is fully detailed with all panel lines, access hatches, antennae, gun ports, etc., already molded in, as well as presheeted foam airfoils and molded fiberglass stab, vertical fin tips, missile rails, cockpit tub and canopy frame. All wood is precut and sanded to a nearly perfect fit. Semi-scale landing-gear struts, machined wheels and tires and pneumatic brakes are available, as are several choices of ordnance and mounting pylons.

FLIGHT PERFORMANCE

TAKEOFF AND LANDING

After fueling up, I double-checked all flight-control directions and steering then set the engine mixture. I taxied the F/A-18 to the end of the runway, turned into the wind and advanced the throttle. Acceleration was good, and after about 400 feet, I fed in a little up-elevator; the Hornet rotated and was airborne. Climb-out was surprisingly steep for the model's weight; the leading-edge root extensions add a lot of lift.

Landings are exceptionally slow for a 14-pound, scale jet that is capable of more than 150mph speeds. Just before touchdown, raise the Hornet's nose to bleed off speed, and the model will touch down on the mains first followed by the nose for a perfect scale landing.

STANDARD FLIGHT AND AEROBATICS

After the model attained a safe altitude, I trimmed the stabilizers. I used only a click or two of elevator but almost all of the aileron trim. I think that this was due to a slight difference in the airfoil at the LE of the wing that occurred when I installed the LE flaps. I set up for an aileron roll downwind. The roll was very axial but a bit slow for my taste at full stick deflection, with no tendency to over-rotate when the stick was released. Next, I tried an Immelmann, building up airspeed in a shallow dive, then applying a little backpressure on the stick. It was obvious as the Hornet entered the maneuver that there was ample power for a large half circle. As f half-rolled out, the nose dropped slightly; a slightly higher roll rate would have helped here. The next two flights reinforced my original impression: set up as per the manual, elevator was adequate, but another 20 to 30 percent could be added to the roll rate. Although I have not yet landed using the LE and TE flaps, I deployed them in slow flight at altitude. The result is an increase in sink rate, which can be compensated with elevator trim. With about 30-percent power, the nose can be held at a higher angle of attack without increasing airspeed. This should allow a lower stall speed as well as landing speed.

OPTIONS

Before beginning construction, there are several choices to make with regard to flight controls. Although the manual suggests that separate aileron and elevator controls are more responsive, the Hornet can also successfully be flown using full flying stabs for both pitch and roll. Also, flaps and rudder are not necessary, so if you want simplicity, two high-powered servos for "taileron" will provide total flight control. Because the Hornet's wing is relatively thin outboard and wouldn't accommodate most servos, I chose to use tailerons for roll and pitch. I also installed rudders, as they are of great help in crosswind situations, and I opted to install flaps, as they would shorten takeoff distances and aid in grass field operation. The full-size Hornet has full-span leading- and trailing-edge (TE) flaps, and since I have always wanted to attempt leading-edge (LE) flaps on a model, I also elected to design these into the lho-scale wing.

Having decided on the flight configuration, I now had to make a choice concerning fuel tanks. The plans show placement of a single, 24-ounce Sullivan tank between the cockpit and the engine, or conformal tanks on either side of the fan. While the conformal tanks make the engine compartment rather cramped, I chose them for two reasons: they are very close to the CG, so pitch trim changes are not necessary as fuel is consumed, and together they hold 31 ounces of fuel--6 ounces more than the single tank.

CONSTRUCTION

The fuselage is an exquisite example of glass work; the amount of detailing molded into the Hornet is impressive, to say the least. The detail is crisp, flawless and, with the exception of the molding seams, needs only a light sanding to be ready for the finish. There are three access hatches in the fuse: the most forward is the cockpit (under which the nose gear is installed), the second begins several inches behind the cockpit and provides starting access (and installation of the 24-ounce Sullivan tank), and the third is between the wings and provides access to the engine compartment. Each hatch is molded separately and is secured by only two small locating pins and a spring-loaded latch. The lips on the aft hatch are quite small and require small pins to position correctly. I used 0.062-inch music wire; the 3/32-inch wire suggested in the manual required that I remove too much material in the already tiny surface. I think Yellow Aircraft should have made these lips a little larger to support the pins. I used the conformal tanks and thought that the open area under the middle hatch was an ideal location for a plywood tray to hold the retract valve and its servo, on/off switch and charge jack, pneumatic fill valve and throttle servo. This shelf provides easy access to these components and room underneath to mount the air tank.