TERRY DUNN
terrydunn74@gmail.com
I equipped the Fox with a Tactic
TR625 (
tacticrc.com) receiver located slightly behind the elevator and rudder servos. All of the servo and ESC leads reached the receiver without requiring any extensions. I routed one of the two receiver antennae into the embedded tube that was originally designed for a long 27 MHz or 72 MHz antenna. The other antenna reaches forward, just above the servos. I programmed my Tactic TTX850
transmitter using the suggested control throws as midrates. I then set high and low rates approximately 20% above and below the midrates, respectively. For good measure, I also programmed 30% exponential throw on every control surface at every rate. I used an ElectriFly 3S 1,000 mAh
SPECIFICATIONS: TYPE: ARF electric sailplane SKILL LEVEL: Beginner WINGSPAN: 70.9 inches LENGTH: 34.6 inches WEIGHT: 24.7 ounces PRICE: $99.98 INFO:
towerhobbies.com
FEATURES: >> Quick, simple assembly >> Hidden control horns >> Nice aerobatic flight with soaring qualities
to help the model balance when using smaller, lighter batteries. The wing panels are reinforced with a carbon-fiber rod. The root of each panel is press fitted into the fuselage. Internal clamps are located at roughly midspan on the panels. Tightening the exposed screws causes the clamps to grip the spar and hold everything in place. It is an unusual system, but it seems to work well.
LiPo battery (
electrifly.com) and placed it forward of the plastic battery tray to get the proper CG (center of gravity). There is plenty of room within the fuselage to move the battery in either direction. All of my preflight number crunching
hinted that the Fox would have plenty of power and fly light on the wing, but there’s really only one way to know for sure.
The Fox’s built-in landing gear is not suitable for taking off, so flights must begin with a hand launch. I prefer to grip the fuselage just behind the wing’s trailing edge. I then power up the motor to at least half-throttle and give the aircraft a moderate horizontal toss. There’s nothing to it. Full power will allow the Fox to
sustain a climb angle of approximately 45°. My GPS data indicates that I’ve reached a top speed of 50 mph with this airplane. That must have been in a dive because average horizontal speeds are noticeably slower (25 to 35 mph). These speeds and the model’s 11
/2 -pound
weight place it firmly within the AMA’s Park Pilot Program guidelines. Control response is good, with full- deflection aileron rolls lasting roughly three seconds. That may sound slow, but don’t forget that this model’s wingspan is nearly 71 inches. Elevator response is especially brisk.
The removable canopy is slightly oversized and it doesn’t blend well with the fuselage.
It’s good for aerobatics, but I flip to low rates to smooth things out while
cruising around or soaring. I was rather surprised by how powerful the rudder is. Not only can the Fox perform decent Hammerhead maneuvers and stall turns, it will hold altitude in knife-edge flight. Aerobatics can be accomplished
with the motor on or off. Obviously, power-off maneuvers require a little extra planning and energy management. Although the Fox is lightweight, it is clean enough to hold energy well while gliding. This becomes evident when you bring
the Fox in for a landing. Depending on the wind conditions, I’ll often chop the throttle early into my downwind leg so that I don’t overshoot the runway on final approach. The Fox may be an aerobatic glider,
but it is also capable of soaring. As soon as I pull the throttle to idle, the propeller stops and folds back, and it’s time to look for lift. I find that it’s best to keep the model moving forward at a brisk pace. Trying to maneuver tightly at slow speeds will cause the Fox to enter a spin. Because there are no decals on the
bottom of the model, it can be tough to see it at soaring altitudes. I plan to add stripes underneath the wing to improve visibility. Flight times depend heavily on how
much gliding you do. With the mix of soaring and aerobatics that I prefer, 10-minute flights are common. I have also flown the Fox with ElectriFly 3S 1,300 mAh and 3S 1,800 mAh LiPo batteries. There is plenty of room to position these larger and heavier batteries while still maintaining the same CG location. Not only do these batteries provide additional motor run time, they act as ballast, which can improve wind penetration while gliding. With these options, you can select the battery to suit the conditions and your flying style. Whether you are considering
the ST Model Fox for flying at the local park or at your club’s field, its performance envelope is broad enough to comfortably cover both domains. It is a sleek-looking model that can perform graceful aerobatics or go searching for thermals. As $100 models go, this one is extremely fun and versatile.
THEPARKPILOT.ORG 25
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