Many, many, Multiplex Fox free flight gliders have under gone conversion to Radio Control, some with power, some as gliders. Which ever rout you chose this is a low cost way to great FUN.
This is by no means the definitive way to convert a Fox to RC, just the way that has suited me.
You do what's good for you.
Before we start let's have a look at the shopping list of parts your going to need.
Shopping list of parts.
10gram Brushless Outrunner & Speed Controller or similar.
4 Channel Micro Receiver.
2 Micro Size Servos (4.6g or similar)
240mAh or similar 2s Lipo Flight Battery
A compete set of parts including Motor, Prop Adapter, ESC, Battery's, Servos & Receiver can also be found at Robot Birds (just click on the link)
Let's start with the tail. First cut a hole to take a 4.3g micro servo, then cut a slot down the length of the fuselage & then push the servo lead in to the slot.
Next take the tail plane and cut out the elevators half's, and bevel the edge's of each elevator. Take a length of carbon rod & join the half's together, making sure that they are spaced correctly so that the overall length remains the same. Trim the centre for clearance.
Hinge the elevator using tape & use a cut down servo arm glued in to a slot as a control horn.
The fuselage. Cut out and remove foam from the fuselage to make space for all the radio gear. you can also use a soldering iron to melt the foam, but please do this in a well ventilated place & be careful not to breve in the toxic fumes from the foam.
Cut and remove the foam from above the wing seat, to allow access to the space under the wing and remove the foam to make space for the aileron servo and radio receiver. Cut and remove the nose remembering to allow for some down thrust, then fit a lite ply former to take the motor mount. Retain the nose piece as this can be trimmed and refitted latter around the motor.
Cut a slot part way through the wing and insert a flat carbon strip spar 0.5mm X 3mm, glue with UHU por. Cut out the ailerons & bevel the edge's. Hinge them with tape & use cut down servo arm's glued in to a slot as a control horn as you did with the elevator. Cut a hole in the centre of the wing to take the micro servo, make a second hole two pass the servo lead through. Fit with UHU por & centre the servo output arm & ailerons. Make up & fit aileron connecting links.
Fit a 10g brushless outrunner to the lite ply plate and place the speed controller in the cockpit area. Install the receiver at the back of the wing seat & connect up the servos and ESC. Run the leads along the bottom of the cut outs,to avoid the aileron servo arm. Next refit the wing and glue the over wing piece back in place.
Remove the ball bearing balance weight from the canopy and fit whatever method of fixing you like.
Refit the Tail plane in place. centre the elevator servo & elevator, then make up & fit a wire control link.
C of G
So that's the build complete & all that's left is setting up the C of G. This should be about 45mm back from the leading edge of the wing. You will properly find initially that you model is nose heavy requiring some weight in the tail. The easiest way I found for this is to bore a hole in the end of the fuzz just under tail. Add the required weight & seal it in the hole with some tape over the end.
Control Throws & Set-up.
Using your Transmitter Dual Rates set up the ailerons and elevator for 5mm movement in each direction, then add to this 40 to 50 % Exponential. This should be a good starting point for the first fligh, after which adjust to sute your own taste.
Go fly & Enjoy