servos anything over 11g to 16g will have enough power to motivate the surfaces if for 1/2A. The trick is use the inner holes on the servo horn less movement but you won't strip gears. You can use the outermost hole in the control horn at the elevator etc.wont load the servo as much.
Hitec HS-65HB Mighty Karbonite Feather Servo 31oz at 6v
http://www.ebay.com/itm/Hitec-HS-65H...ht_3344wt_1086
Includes: 4 Serov with Hardware
Specifications:
- Motor Type: 3 Pole
- Bearing Type: Top Ball Bearing
- Speed (4.8V/6.0V): 0.14 / 0.11 sec @ 60 deg.
- Torque oz./in. (4.8V/6.0V): 25 / 31
- Torque kg./cm. (4.8V/6.0V): 1.8 / 2.2
- Size in Inches: 0.92 x 0.45 x 0.94
- Size in Millimeters: 23.34 x 11.43 x 23.88
- Weight ounces: 0.39
- Weight grams: 11.06