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Technical Specifications
Last Updated: 2026-09-08| Identity | |
| Brand |  |
| Product Number | JRPS821 |
| Category | Hobby |
| Discontinued | Yes |
| Performance | |
| Torque |
6.0V
88.00 oz-in
6.34 kg-cm
0.6 N-m
4.8V
72.00 oz-in
5.18 kg-cm
0.5 N-m
Bottom 10%
|
| Speed |
6.0V
0.15 sec/60°
400.0 deg/s
66.7 RPM
4.8V
0.19 sec/60°
315.8 deg/s
52.6 RPM
Below Average
|
| Stall Current | 0.93–1.09 A930–1090 mATop 10% |
| Physical | |
| Weight | 1.50 oz42.5 gTop 10% |
| Dimensions |
L 1.50 in W 0.74 in H 1.47 in L 38.1 mm W 18.8 mm H 37.3 mm |
| Case Material | Plastic |
| Drivetrain | |
| Motor Type | 3-pole |
| Gears | Nylon |
| Gear Spline/Teeth | 23 T estimate |
| Rotation Mode | Positional |
| Rotation/Support | Single Bearing |
| Control & Signal | |
| Modulation | Digital |
| Pulse Width | 1000-2000 µs |
| Neutral Position | 1500 µs |
| Angle Sensor | Potentiometer |
| Control System | PWM |
| Programmable | No |
| Electrical & Environment | |
| Operating Voltage | 4.8–6 V |
| Power Source | Direct |
| Regulator Type | Direct |
| Certification | CE |
| Connectivity | |
| Connector | JR (Universal) |
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
| Torque | Bottom 10% Stronger than 10% of 1061 Digital Standard servos at 4.8V |
| Speed | Below Average Faster than 15% of 1044 Digital Standard servos at 4.8V |
| Weight | Top 10% Lighter than 94% of 1879 Digital Standard servos |
| Stall Current | Top 10% Lower draw than 96% of 570 Digital Standard servos |
Performance Analysis
| Shaft Power | 0.70–1.08 W |
| Power Density | 0.665 W/in³ More power-dense than 7% of 1768 Digital Standard servos |
| Torque Density | 1.6941 oz-in/g Stronger than 14% of 1054 Digital Standard servos |
| Torque-to-Volume Ratio | 44.13 oz-in/in³ Denser torque than 11% of 1059 Digital Standard servos |
| Speed-to-Weight | 0.12384 (1/sec·g) Faster than 57% of 1037 Digital Standard servos |
| Speed-Torque Trade-off | 13.68 Better balanced than 21% of 1035 Digital Standard servos |
| Current-per-Torque Ratio | 0.0151 A/oz-in More efficient than 49% of 329 Digital Standard servos |
| Torque Gain per Volt | 18.52%/V More voltage-responsive (torque) than 71% of 873 Digital Standard servos |
| Speed Gain per Volt | 22.22%/V More voltage-responsive (speed) than 87% of 873 Digital Standard servos |
| Voltage Range Width | 1.2 V Wider voltage range than 21% of 1560 Digital Standard servos |
| Dead-Band-to-Pulse-Width Ratio | 0.0000 1st-highest dead-band-to-pulse-width ratio of 496 Digital Standard servos |
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Reviews (6)
-
Jaden Lobbia
June 7, 2021Application(s): Thunder Tiger Raptor 30 V2
Comments: Used as my cyclic servos, and for my collective. When rebuilding the output gear on the collective servo broke clean off. I don't know if it's user error or not.
Russ
May 3, 2019Application(s): Sig Kadet Mark II w/OS 46LA
Comments: I lost my plane on the 3rd flight , doing a Loop with a Snap Roll on Top ,, lost the Elevator 75% of the way thought the loop and it flow in to the ground .. Out put shaft of the DS821 snapped , I used NO lock Tight or any thing else on it Will never use a DS821 ever again
Joel
December 8, 2014Application(s): All around except throttle, OMP Yak
Comments: First servos I ever bought, six plus years now, sent them in a year ago and they all checked out fine. Recently bought more to replace Hitecs, my 5245 jammed and crashed my plane, no more Hitec for me.
Jimmy
November 22, 2014Application(s): Seagull Edge 540, OS120, throttle servo
Comments: I lost a nice Seagull edge 540 when the throttle servo
gears jamed and it pulled the battery voltage down
to 3.5v, causing the other servos to wander around
aimlessly. I wouldn't recomend this servo on anything.
I'm also switching to Hitec servos in the future.Duckby
January 4, 2012Application(s): Extra 330 68" span all EX rudder
Comments: good nice servo for the price NEVER USE THREAD LOCK it kills the gears. good sports servo not doing 3D so no need for silly fast speeds. done 50 flights with them now with no problems and still tight..
artgorgeous
March 3, 2010Application(s): for my invention
Comments: Very good servo. Powerful and fast.