Written by Dave Lockhart New design adds rigidity while remaining lightweight and nimble As seen in the Spring 2014 issue of Park Pilot
Fancy Foam Models is known for its extensive line of Depron and EPP (expanded polypropylene) foam indoor and outdoor models, including everything from trainers to novelty vehicles and extreme aerobats. The 42-inch Extra 330s and MX2 aircraft are closely related, sharing unique, box-type fuselage construction and an airfoil wing. Most of the airplanes’ construction is durable EPP foam, but the construction design is rigid. Although the Extra 330s is the subject of this review, the content is 99% applicable to the MX2.
To get the Extra 330s flying, you need a 480-class brushless motor (250-350 watts), 30-amp speed control, four 9- to 12-gram servos, a receiver, and a three-cell 1,800 to 2,250 mAh LiPo battery. Alternatively, a lightweight power system can be selected using a 400-class motor (200 watts), 20-amp speed control, and a three-cell 1,200 to 1,500 mAh LiPo battery. The Fancy Foam Models website includes all items needed to get this model in the air.
Opting for items already in my shop, I used a relatively high-powered motor—a 1,020 Kv E-flite Park 480—and a Castle Creations Talon 35-amp speed control. To keep the weight down, I selected a midsize, high discharge Thunder Power RC 3S 1,800 mAh 65C battery. For the radio equipment, I used Spektrum 3040 servos with a JR RG611B receiver and a JR XG14 transmitter.
The kit’s parts count is low. The fuselage consists of two sides, a bottom piece, top piece, top hatch, one former, and a battery support. The ailerons are precut from the one-piece airfoil wing and the hinge lines for the ailerons, elevator, and rudder are prebeveled. Hinging the control surfaces uses a “live hinge,” which is detailed in the instructions and the online building/flying thread at rcgroups.com/forums/showthread.php?t=1756476.
With a low parts count, minimal assembly is required.
For construction, I used the recommended Beacon Foam-Tac, which is a clear, flexible, one-part glue suitable for use on a wide variety of foams. Using Foam-Tac as a contact adhesive, a small bead of glue is applied to one side of the glue joint. The parts are pressed lightly together to distribute the glue, then pulled apart to dry for 5-10 seconds. When the parts are rejoined, the initial tack is aggressive, and a full strength bond is achieved in 24 hours. While building, I only waited a couple of minutes before proceeding to the next step, and never had a glue-joint failure.
Construction starts with the addition of the carbon-fiber wing spars and elevator reinforcement. The aileron servos are installed and the servo leads are routed to the center of the wing. Join the fuselage sides to the bottom with the addition of a support former midway between the stabilizer and wing.
Slide the wing and stabilizer into place and glue them, then add the vertical fin. Add the firewall and battery support, and then install the rest of the equipment and control linkages.
The elevator and rudder servos are mounted in the tail with extension leads to reach the receiver located near the wing spars. The supplied linkages consist of metal Z-bends that attach to the carbon-fiber pushrods with slip-fit heat shrink, allowing the exact pushrod length to be easily achieved before shrinking the tubing.
Tail-mounted servos provide direct, precise control of the rudder and elevator allowing the fuselage to flex without damaging pushrods in the event of hard landings or crashes.
Shield the foam with a piece of cardboard, and apply a small drop of CA on the edge of the heat shrink to lock everything in place. The linkage design allows the Z-bends to break loose in a crash, preventing servo-gear damage. For increased precision, I made my own linkages from carbon rod and micro ball links.
The Park 480 motor I used is slightly on the short side for 480-class motors, so I used a couple of nylon bushings to space the motor forward so the propeller would clear the front edges of the fuselage. Optionally, the fuselage nose can be trimmed slightly.
With the equipment installed, the fuselage top is added, and the top hatch is put in place. Foam-Tac was used to create a live hinge on one end of the hatch, while a tab secures the opposite end of the hatch.
The recommended low/high control throws are 25°-40° for elevator, 20°-50° for ailerons, and 20°-35° for rudder. I highly recommend using exponential, especially on high rates. On high/low rates, I ended up using approximately 80%/20% on ailerons and elevator, and 45%/25% on rudder. The recommended CG of 4 inches aft of the wing’s leading edge is easy to achieve with a wide range of batteries.
Rudder authority is excellent, making knife-edge flight easy. Even knife loops need few corrections.
At a flying weight of 24 ounces, the Extra 330s is an impressive performer. It can fly slowly enough to be comfortable in a small baseball diamond, but is still a solid performer when the wind picks up.
At the recommended CG location, control authority is outstanding in all axes, even at low speed, and the airplane is stable in turbulent winds. The high-speed roll rate is a blur. Knife-edge loops are easily accomplished with little tendency to pitch or roll. Slow flight harriers are stable and possible at high or low angles of attack.
With the abilities to fly aggressive 3-D, or precision pattern-style maneuvers, this little Extra has become my favorite lunchtime model and performs like a much larger airplane.
