Multiplex Fox RC Conversion

The Multiplex Fox is a free flight glider and has two great features: it's cheap and it bounces as it is made from Elapor.
It flies fine as a free flight model, but ends up a little heavy when a motor and RC gear are added. Specialist light weight gear is available but delicate and expensive. The addition of RC gear has increased the weight from 40 to 75 grams
The motor, servos, battery and speed controller I used are all cheap Chinese parts from Hong Kong. The Spektrum receiver was 40 with the JST extension lead needed to connect the speed controller.

The wing is strengthened with a 0.5 x 3mm carbon spar, ailerons hinged with Mylar, the foam cut with a scalpel or melted out with the handle of a heated spoon, very little skill is need to convert this model. 
There are many forum threads on Fox RC conversions, but the fun is in doing it your way.

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9 gram 2000 kv brushless with a Gunther prop, the motor is recessed and glued in with industrial strength silicone. It draws about 1 amp in cruise and should give 14 mins of flight time

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Spektrum AR6300 2 gram park flyer receiver with JST plugs , fitted near the servos to save extending the wires

A 6amp speed controller,  the 250 mah 2s battery goes under the wing

Above heatshrink tubing is used to hinge the aileron horn to the push rod

The elevator has an  internal linkage, the rear of the fuselage was cut off, the elevator horn fitted then glued back on

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2.5 gram servos fitted behind the wing inside the fuselage, I think these are the smallest available in normal configuration, the weight of the servos balances the weight of the motor and allows the battery to be on the C of G which is on the wing spar. 

For such a small model it is very stable, so stable that it is not very aerobatic, this is no surprise as it is meant to be a free flight model. 
Rolls, loops and inverted are OK but do require full power with a lot of down needed in the inverted part of the roll, inverted is hard as the model is trying to right it self.
Indoors the wing loading makes it a little too fast, it will just loop and roll inside the dome at Bentham

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Flying on Minchinhampton common 28/12/09

Wingspan: 500 mm, 
Length: 475 mm,
Weight 75 g all up
Battery 250 mah 2 cell 12 grams


Gloucester Model Flying Club