Blog – RC Vehicules

Most RC planes we encounter come with the complete pack, ailerons, elevators, and rudders. These components are used to control the plane movement in three dimensions, direction, altitude, and orientation. But are they all necessary, or we can manage with only one or two of them? As a general rule, RC planes can fly without ailerons, elevators, or rudders, although their ability to maneuver will be very limited. However, they can rely on alternative methods of control. Using a combination of ailerons and elevators is common, but missing of one of these will make it hard to control the plane. In this article, we'll explain what each of these components does, dive deeper into their roles in controlling the plane, and explore how we can compensate for the absence of any one of them. Keep reading! What Are Ailerons? Ailerons are one of the three main control surfaces used to pilot an RC plane. They are integrated into the wings, and their movements control the plane's rotation, allowing it to roll, which is the rotation around its longitudinal axis. Ailerons are located near the wingtips and move in the opposite direction from each other. When you adjust the ailerons, one moves upward while the other moves downward, which allows the plane to roll in the direction of the wing with the lowered aileron. The aerodynamics behind the aileron function are pretty simple. Ailerons use air pressure to rotate the plane. When one aileron moves upward, it reduces the air pressure on that part of the wing surface, increasing the lift. The aileron moving downward does the opposite, increasing the air pressure across the bottom of the wing surface, and this difference makes the plane roll to the side. A simple example, imagine you're in a car going at a high speed, if you get your hand out of the window, you'll feel the air pushing your hand back. When your hand is oriented flat and horizontal, the pressure will be much smaller. If you leave your palm in the same position and move your elbow downward (aileron moving down), at that moment the air will push your hand up and not back. Vice versa, if you move your elbow up, the air will push your hand down. Can an RC Plane Fly Without Ailerons? There are multiple RC planes in the market that come with no ailerons, so the short answer is that your RC plane can fly without ailerons. However, flying an RC plane without ailerons limits maneuverability and puts you under the constraint of maintaining stability through other design aspects and control methods. In the absence of ailerons, the rudder becomes the primary control surface for making turns. These turns will be less sharp than those achieved with ailerons. The rudder can be effective for basic flight maneuvers and gentle banking turns. Another design aspect that helps keep the plane stable without the ailerons is the dihedral wing configuration, which involves angling the wings upward from the fuselage, as shown in the video below. Many beginners, including those I know, start their RC flying journey with planes that lack ailerons because they are easier to fly due to the simplified controls. https://www.youtube.com/watch?v=gsv2toB9Bb8 What Is an Elevator? An elevator is a control surface on the airplane that regulates its movement on the lateral axis, affecting its altitude by controlling the pitch - its up or down orientation. The elevator is located at the rear of the plane. The main purpose of an elevator is to allow the plane to climb, descend, or maintain level flight. When the pilot pushes the control stick forward on their controller, the elevators move downward. This action is based on the same principle explained in the ailerons section. The movement of the elevators alters the air pressure over their surface, causing the plane to change its pitch. The key difference is that the elevator's location at the back of the plane allows it to control the aircraft's up and down movement, rather than rolling from side to side. Can an RC Plane Fly Without an Elevator? RC planes can fly without an elevator, although they will need a very specific design to make up for the absence of the elevator. Also, their controllability will be limited since the elevator is the main responsible for controlling altitude. Some RC planes are designed without an elevator, such as those with v-tails and flying wings. These models use alternative design features to cover the elevator role, such as the elevons, which are control surfaces that combine the functions of elevators and ailerons. The elevons are located in the wings and the main difference between them and ailerons is their ability to move in the same direction, employing simple aerodynamics. The difference between ailerons and elevators is that ailerons move in opposite directions, while elevators move always in the same direction. If the ailerons can move in the same direction then they can cover elevators. The principle behind those functions is that if the ailerons move in opposite directions, one side of the plane will go upward, and the other will go downward causing the plane to roll. On the other hand, if they move in the same direction, both sides of the plane will move upwards (or downwards) which will cause the plane to gain (or lose) altitude. What Is a Rudder? The rudder is a primary flight control surface attached to the vertical stabilizer at the rear of an RC plane. It's used to control the plane's yaw, which is the rotation around the vertical axis. By moving the rudder, the pilot can change the direction of the airplane's nose. However, it's not primarily used to turn the plane, that's the aileron's job. It's designed to overcome adverse yaw during aileron-initiated turns and to help align the aircraft during crosswind landings. The rudder's function is similar to that of the other control surfaces. Its movement changes the air pressure on a surface which makes the plane turn on its vertical axis. Below is an illustration of the rudder function. You should be used to using the rudder during your training. I have seen many pilots that don't use it even after years of practice. Using the mix of rudder/ailerons improves your turns by handling the counteracting yaw. By coordinating the rudder to move in the same direction as the ailerons, you can prevent the nose from skidding sideways during turns. I recently began wondering if it's possible to program the rudder to turn automatically with ailerons, I thought I had a genius idea :). Eventually, I found out after research on the internet that it's a common practice called "aileron-rudder mixing" and it's not that hard to set up. Here's a video summarizing what we have said. https://www.youtube.com/watch?v=c5Tnc1seems Can an RC Plane Fly Without a Rudder? RC planes can fly without a rudder, it's even common for them to have only ailerons, and multiple pilots depend heavily on other controls to maintain stability even if they have the rudder. The downside is that the maneuvers and directional control will be limited especially during windly conditions. I know multiple pilots who didn't start to use the rudder until they spent a few years in the hobby. They use ailerons to replace the rudder role during turns. However, without a rudder, handling crosswinds during takeoffs and landings becomes more challenging.