How to Set Up Servos and Control Horns in Aircraft

Servos and control horns play a major role in the way aircraft achieve flight. Without the proper set up, these flight control surfaces can have adverse effects on flight which must be avoided. To better understand their importance, this blog will outline how to set up servos and control horns correctly.

Aircraft flight control surfaces are aerodynamic devices that enable pilots to adjust and control an aircraft’s flight attitude. It is paramount that these surfaces have the ability to move freely without binding to different parts of the airframe. More than that, one must ensure that the flight control surfaces return to the same position every time.

Other common issues include incorrectly aligned hinges, tight linkages, debris caught in the linkages, a loose-fitting control horn, and more. However, these issues can be remedied with careful attention. Hinges, for example, can be easily replaced, but the cuts must be straight. If the hinges are not straight, then binding will occur. Additionally, one should tighten any loose control horn, and repack the horn, only if necessary, as the foam may compress over time.

The linkage systems in particular are often overlooked, despite being a major area of concern. As such, you must check your servo, servo arms, pushrods, and control horns for worn down, loose, or ill-fitting parts. Some manufacturers may include parts that are not suitable, resulting in the deflection or fluttering of control surfaces. Properly fitted parts are key to ensuring everything is working optimally, so one must take their time in installing linkages.

Meanwhile, servo arms must move parallel to the pushrod components, as they are not designed for side forces. Control horns are actually at their strongest when force is applied this way. It is important to note that a side force may twist or fracture the horn leading to inflight failure. Moreover, one must ensure that a servo does not travel beyond what is required as this may overdrive a control surface or cause a horn hinge to fail.

Generally, most manufacturers utilize the middle hole in the horn and servo arm. While this is fine for some models, other aircraft may benefit from a higher-resolution or a more precise control surface. Control can be made more precise but at the cost of travel. To increase the resolution or make a control surface more accurate, the control rod must be moved to the innermost hole on the servo arm and the outermost hole on the horn.

In terms of cost, there is little difference in control horn quality. Typically, nylon or carbon-reinforced plastic horns are favored for their robust quality and fatigue resistance. Plastic horns are great options for small indoor flyers. Servo selection, on the other hand, consists of acquiring servos that can exert a greater force than what the manufacturer recommends for your aircraft.

If you find yourself in need of flight control surfaces, such as control horns, servos, rudders, ailerons, elevators, and more, rely on ASAP Axis. ASAP Axis is a leading distributor of aircraft parts and components, all of which have been subjected to varying levels of quality assurance measures, tests, and verifications. With over 2 billion new, used, obsolete, and hard-to-find options, customers can easily fulfill their operational requirements. Get started with a quote request on any featured item which can be accessed through our Instant RFQ service and within 15 minutes of submission, a dedicated representative will reach out with a competitive solution that keeps your part needs in mind. For additional inquiries, call or email us at any time; we are available 24/7x365!