JR PROPO S8511 Standard-Size Servo with Metal Gears
The JR PROPO S8511 is a standard-size servo equipped with high-strength steel (nitrided) metal gears and a coreless motor, delivering reliable performance across a wide range of aircraft types—from scale models to aerobatic planes.
You can use this servo for planes of 50cc or smaller size.
With a torque output of 347.2oz-in(25 kg·cm) and a speed of 0.1 sec/60°, this servo offers both power and responsiveness. The plastic case is reinforced for durability, and the gear shaft is supported by an enlarged metal bushing to reduce play and enhance stability. The S8511 is engineered to deliver high performance while maintaining excellent cost-effectiveness.
This servo also features computer programmability, allowing users to fine-tune holding power and damping to suit specific aircraft characteristics. The operational angle can be set to either 120° or 180°, and once programmed, the settings are stored directly in the servo—allowing use with other brands of transmitters while retaining the configured performance.
Specifications:
Stall Torque: 272.8oz-in 19.6 kg·cm (6.6V) 305.9oz-in  22.0 kg·cm (7.4V) 347.2oz-in  25.0 kg·cm (8.4V)
Speed (sec/60°): 0.14 sec (6.6V) 0.12 sec (7.4V) 0.11 sec (8.4V)
Weight: 65 g (2.29 oz)
Dimensions: 40 x 21 x 40.5 mm
Lead Length: 300 mm
Operating Voltage: 4.5V – 8.4V
Features:
Coreless Motor
Programmable Functionality
Full Metal Gears
Full Metal Case
Wide Voltage Compatibility
Dual Ball Bearings
Adjustable Operating Angle: 120° / 180° (150° via XBUS SERVO PROGRAMMER)(*Servo horn not included)
Usage Notes:
JR servos use high-frequency control, which may make it difficult to hear the alarm sound during servo lock.
When using multiple servos for a single control surface or for flaps, take care to avoid servo conflict or overdriving.
Any looseness in the linkage, servo arm, or gear can lead to hunting (oscillation).
Using a longer servo horn than the control surface horn may cause force imbalance, resulting in insufficient torque and potential servo failure.
When using this servo for throttle on engine-powered models, always apply proper vibration isolation with rubber grommets.
Strong holding servos may fail quickly if exposed to excessive engine vibration. Adjust linkages or reduce holding power/damping using programmable parameters (set HOLD and DAMPING to negative values).
Ensure throttle stroke settings have slight margins on both high and low ends to avoid binding.
Avoid using spiral-type extension cables, as they can increase inductance and interfere with signal accuracy, possibly disabling XBUS communication or causing malfunctions.
Do not use servos that have been submerged in water to ensure flight safety.