JR SPORT Servo Guide

  • 01/23/2006 by
  • Copyright:© 2006 Horizon Hobby, Inc.

A servo is just a servo, right? Not if it’s a JR SPORT™ servo. JR SPORT servos have been designed by modelers with years of experience in a variety of applications. Whether you’re the person who takes a plane with them to work so they can fly a park flyer after their shift or the person without any previous experience who wants a great servo at a great price, JR SPORT should be at the top of your list. You will find that many little details were incorporated into each and every component of a JR SPORT servo, and that the details are what set them apart from the crowd.


With ultralites, foamies, and park flyers, the weight of your equipment is crucial to the overall performance of your aircraft. This is especially true in the smallest of park flyers out there, as having more weight on the nose or tail can adversely affect the flight characteristics. This is where having a small and lightweight servo is especially critical. But being small and lightweight is useless unless you have the speed, torque, and reliability needed for a particular application. This is where the SM8 comes into play. The SM8 is equipped with quality silver-plated connectors and features 8 oz/in (198g) of torque with a transit time of .08 seconds at 4.8 volts (.06 seconds at 6.0 volts). The SM8 delivers these outstanding features and specs all while weighing in at a scant 0.21 oz (6.0g). This is one lightning-fast servo with the holding power for the precise control indoors required by demanding pilots, while not forcing you to pay a weight penalty.


Often, sub-micro servos use smaller internal components in an effort to reduce the overall size of the casing. The geartrain is often one component that is shrunk down, which also reduces the durability of a servo as well. Not so on the SM22, as the SM22 uses a larger diameter output shaft to increase durability and performance. The SM22’s size, torque, speed, and durability makes it the perfect choice for indoor flyers, slow flyers, and many micro-sized helicopters as well. When you add all these features together, you get the king of sub-micro servos, the SM22.


Having a servo that’s lazy or underpowered can be really frustrating when you’re flying. The faster a plane travels, the smaller the margin of error will be. A slow or underpowered servo will not have the holding or staying power to move and maintain the angle of a control surface. While some micro servos suffer from this underpowered tendency, the MC35 has the torque and speed you desire with the reliability you deserve. Ideal for planes with 60- to 80-inch wingspans and 2-meter sailplanes, the MC35 is equipped with a 12-inch long lead, eliminating the need for extensions in some applications. The MC35 has been designed to be both accurate and durable, featuring a large diameter output spline for increased strength and durability. The nylon gears have also been molded to better withstand wear and tear while still operating smoothly. Having a servo that doesn’t center properly can be really frustrating, but the motor and electronics inside the tiny MC35 casing offer the accurate centering characteristics that pilots have come to expect from more expensive servos. With its speed and torque, the SM35 is an awesome value for a sub-micro servo.

Most sport pilots could care less which nameplate is on a servo case. What they want is something that works reliably without costing an arm and a leg. This is exactly where JR SPORT™ comes into play. As you can tell, not only are JR SPORT servos easy to shop for and use, they have the value, performance, and features that make them the logical choice for a wide variety of applications. Perfect for use in park flyers, foamies, trainers, and more, JR SPORT brings you the performance and quality you deserve at an outstanding price.


Whether you’re flying Q-40 or Q-500 pylon races or .25- to .40- sized aerobatic planes, you want a servo that’s going to have the speed and torque that allows you to maneuver as fast as you can think. This is where a servo such as the MN48 comes into play. The smaller mini casing reduces weight, yet the MN48 has similar torque and speed ratings to a standard-sized servo. Thanks to its speed, size, weight, performance, and miniscule price, many folks here at Horizon Hobby expect to see the JR SPORT MN48 being used by many competitive pilots; it’s simply that good.


When talking about standard servos, many pilots associate the word “standard” with the word “cheap.” This is not the case with the ST47 and ST47BB, as they have passed tests that other manufacturers wouldn’t even think of putting their equipment through. During the design and testing phase for the ST47, the potentiometers were tested for a total of one million cycles without failure! Talk about durability and reliability that you can count on. Perfect for an aerobatic plane, or any .40- to .90-sized airplanes, the ST47 or ST47BB servos have smooth gear trains and are plenty durable. Plus, when you add in the ball bearing supported output shaft on the ST47BB, it operates even smoother, freer, and truer.



A servo that works well is often forgotten about. In fact, you tend to take its reliability for granted because it does work exactly as you want every time. Unlike a rudder, flap, or even throttle servo, a retract servo only gets used twice during a flight: right after take off and just before a landing. With its low-profile design, the RT88 fits easily into the wings without requiring major modifications to the wing itself. The RT88 has gone though all the same developmental stages as other JR SPORT servos, giving you the confidence and peace of mind that when you need it, the RT88 will be there to do its job for you. The RT88 has the speed and torque you desire, yet delivers that performance at a budget-friendly price


You can’t settle for just any old servo when flying larger scale planes or warbirds; there’s just too much that could go wrong if you lose control. When you’re looking for holding and staying power, a high torque metal-gear servo should be at the top of your list. When flying both large scale and faster airplanes, the higher air pressures placed on control surfaces require more torque to maneuver and hold a control surface in the desired position. The ST126MG has over 126 oz/in of torque at 4.8 volts, or a whopping 142 oz/in of torque at 6.0 volts; that’s some serious holding power. The anodized metal gears provide strength and dependability that rivals digital servos. Additionally, the output shaft of the ST126MG is ball bearing supported, which further enhances the precision of what was already an awesome servo.

Model Number


Ratings @ 4.8V

Ratings @ 6.0V



Our Price


SM8 Super-Micro

7oz/in — .08 sec.

8.5oz/in — .06 sec.


0.21oz (6.0g)



SM22 Sub-Micro

20oz/in — .16 sec.

.22oz/in — .11 sec.


0.32oz (9.07g)



MC35 Micro

30oz/in — .21 sec.

35oz/in — .17 sec.


0.6oz (17.1g)



MN48 Mini

48oz/in — .18 sec.

57oz/in — .15 sec.


0.8oz (22.68g)



ST47 Standard

47oz/in — .24 sec.

55oz/in — .19 sec.


1.55oz (43.94g)



ST47BB Standard Ball Bearing

47oz/in — .24 sec.

55oz/in — .19 sec.


1.55oz (43.94g)



MG126 High-Torque

126oz/in — .21 sec.

142oz/in — .17 sec.


1.60oz (43.6g)



RT88 Retract

88oz/in — 1.12 sec.

105oz/in — .90 sec.


1.15oz (32.6g)



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