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Blue Bird BMS-621MG
Standard

Blue Bird BMS-621MG

Compatible Hardware

*Spec is estimated from brand data.

Technical Specifications

Last Updated: 2026-09-16
Identity
Brand Blue Bird
Category Hobby
Performance
Torque
6.0V 100.00 oz-in
4.8V 89.00 oz-in
Speed
6.0V 0.10 sec/60°
4.8V 0.13 sec/60°
Physical
Weight 1.66 ozAverage
Dimensions L 1.594 in
W 0.787 in
H 1.496 in
Drivetrain
Motor Type 3-pole
Gears Metal
Gear Spline/Teeth 25 T estimate
Rotation Mode Positional
Rotation/Support Dual Bearings
Control & Signal
Modulation Analog
Pulse Cycle 8 ms
Neutral Position 1520 µs
Refresh Rate 125 Hz
Control System PWM
Electrical & Environment
Operating Voltage 4.5–6.5 V
Connectivity
Connector JR (Universal)
Origin
Country of Origin Taiwan

Disclaimer: Most data is sourced from the manufacturer. Some data is sourced from our loyal community and with the help of AI. We aim for accuracy but are not responsible for inaccurate information.

Class Comparison

WeightAverage
Lighter than 58% of 447 Analog Standard servos

Performance Analysis

Shaft Power 1.27–1.85 W
Power Density0.985 W/in³
More power-dense than 78% of 432 Analog Standard servos
Torque Density1.8936 oz-in/g
Torque-to-Volume Ratio47.42 oz-in/in³
Speed-to-Weight0.16367 (1/sec·g)
Speed-Torque Trade-off11.57
Voltage Range Width2.0 V
Wider voltage range than 90% of 239 Analog Standard servos

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Reviews (1)

Includes 1 review aggregated from around the web.

There are few reviews for this servo on the web. A German forum owner using it for steering is very happy, calling it fast and reliable, and says it has survived several heavy crashes. A Reddit user says the Bluebird line is a good budget choice and that their similar 620MG survived far more water than expected.

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