How to convert EPP glider into twin-engine radio control two channel airplane. RC

PART TWO: How to make a twin-engine radio control three channel airplane from EPP glider. Aliexpress. RC
• Como hacer avion bimot...
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We have purchased a manual launch glider made with EPP foam. These gliders have a wingspan of 48 centimeters, and a fuselage length of 46 centimeters. They can be found for a price of 3 euros.
The weight of the plane is 52 grams, but if we remove the cabin, the weight is 35 grams.
We prepared a first version of the plane with a brushed motor of 85 by 20 millimeters and a propeller of 55 millimeters. This motor have a thrust of 23 grams using a 3.7 volt battery. We use a FlySky receiver and an ESC for DC motors with a maximum amperage of 10 amps.
We place the motor in rear configuration, that is, placed behind the wing and pushing forward. We tilt the motor shaft so that the thrust line passes through the center of gravity of the aircraft, which is usually located in the first third of the wing. Thus we avoid that the airplane has an accused tendency to pitch down. We prepare a support for this from a piece of extruded polystyrene.
The plane, as it is, has a natural tendency to yaw to the right. This adverse yaw is due to the incidence of the propeller slipstream on the vertical stabilizer. To correct this effect, we placed a small rudder made with extruded polystyrene taken from a food tray. We apply to the rudder a fixed angle of a few degrees to the left. This corrects the adverse yaw of the plane.
Finally, we apply a dihedral angle by tensing the wings with a thread. The dihedral angle will help the lateral stability of the aircraft, and will correct the tendency of the aircraft to go into a spin.
The final weight of the aircraft is 71.5 grams, then the thrust to weight ratio is 0.32. The wing load is 1.8 kilograms per square meter. The cubic wing load is 9.
Next, we see some images of the flight of the plane.
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Next, we plan to add a 3.7 gram weight servo to control the direction of the plane. So we changed the 3.7-volt battery for a 7.4-volt, 500-milliamp-hour battery, which weighs 30 grams. We prepare a twin-engine plane that supports the weight gain provided by the new battery. We use a pair of identical motors of type N30, with propellers of 75 millimeters. These motors, connected in parallel to the 7.4 volt battery, give a maximum thrust of about 40 grams.
The rudder has been placed in a lower height, so that the barycenter of its surface is located almost at the same height as the aircraft's center of gravity. This will cause the plane to rotate in a horizontal plane when the rudder is apply. If the barycenter was very high, the plane would turn in an inclined plane, affecting its stability.
To improve the aerodynamics of the airplane, we cover the battery with the cabin. The cabin has been previously hollowed out to reduce its weight. In addition, we place the receiver plus the ESC in a hollow of the fuselage. All cables are carefully attached to the fuselage so that they do not disturb the air flow.
The final weight of the aircraft is 114'5 grams, then thrust to weight ratio is 0'35. The alar load is now 2'9 kilograms per square meter. The cubic wing load is now 14'6.
Next, we see some images of the flight of the plane.