Remote Controlled Helicopters
How Remote Controlled Helicopters Work
Attention…Please get Remote Controlled Helicopters training or RC helicopter help before trying to fly model RC helicopters.
Click here to learn how to set up your helicopter for it’s first flight.
RC helicopters are the most versatile mode of flying machine there is and gives the pilot complete access to a fully 3-dimensional space. Remote Controlled helicopters are one of the most difficult vehicles to learn to control.
Here’s an example:
A train can travel forwards and backwards.
A car can travel forwards, backwards,
An airplane can travel forwards, left, right, up and down.
Whereas a remote controlled helicopters can travel forwards, backwards, left, right, up and down. Plus it can also rotate 360 degrees in either direction and do it while inverted.
In a real helicopter, the pilot is facing forwards controlling the cyclic with one hand and the collective with the other.
With a RC helicopter, you’re not always looking the same way the helicopter is flying which makes it difficult to keep oriented and stay in control.
So, how does an radio controlled helicopter fly?
A model RC helicopters flight can be broken into 5 basic components and their functions. The main rotor, tail rotor, swash plate assembly, collective control and cyclic control.
The Main Rotor
A conventional remote controlled helicopter have its main rotor above the fuselage which consists of 2 rotor blades extending out from a central rotor head, or hub assembly.
The main rotor is what produces the lifting force that allows the RC helicopter to fly. The rotors on a collective pitch RC helicopter are shaped just like the airfoils of an airplane wing, only they are thinner, narrower and both sides are symmetrical.
As the rotor blades turn through the air, they generate lift. The amount of lift generated is determined by the pitch angle (and speed) of each rotor blade as it moves through the air. Pitch angle is referred to as the angle of attack of the rotors.
Some remote control helicopter models which use fixed pitch rotors, generate lift by speeding up or slowing down, changing the speed of the main rotors. This results in a much slower responsiveness of the heli, since it takes some for the motor speed to speed up or slow down.
Depending on how the remote controlled helicopters is set up, the main rotors typically spin at a constant head-speed anywhere between 1,500 RPM to 3,000RPM. Larger size .60 or .90 RC helicopters should have a head-speed of 1,500RPM to 2,000RPM where smaller .30 or .50 size heli’s should have a head-speed in the 2,000RPM to 3,000RPM range.
To increase lifting power, you need to increase the pitch of the main rotor. On an RC helicopter, the angle of attach (pitch) can be between +15 degrees to -15 degrees, though most RC heli’s are somewhere in the +11 to -11 range.
The pitch of the blades are controlled by the collective and the cyclic control which are transferred to the main rotors through the swash plate.
The Tail Rotor
Since Newton’s law states that “For every force, there is an equal and opposite reaction force,” as soon as the RC helicopter leaves the ground, there is nothing to keep the helicopter from spinning in an opposite direction of the torque generated by the main rotors.
To stop the spinning of the fuselage, a force which counteracts the force of the main rotors needs to be applied to stop it. In a single rotor RC helicopter, this is done by a smaller set of rotors attached to a long tail boom called the tail rotor, which is used to control the yaw,(rotation) of the helicopter.
The amount of thrust is determined by the angle of attack of the tail rotor.
Increasing the pitch (angle of attach) of the tail rotor blades will increase the thrust, which will push the helicopter in the same direction as the main rotor blades, while decreasing the pitch, allowing the natural torque force of the main rotors to take over rotating the fuselage in the opposite direction to the main rotors.
A gyro, either mechanical or piezoelectric, measures the difference in rotational force between the helicopter and tail rotor and adjusts the pitch of the tail rotor automatically to hold the remote controlled helicopters fuselage straight.
The tail rotor is mounted at a 90 degree angle from the main rotor and provides a sideways thrust which counteracts the rotational force applied by the main rotors to hold it straight.
The tail rotor typically turns 3 – 6 times faster than the main rotor.
Tail rotors in remote controlled helicopters are driven by a belt or a drive shaft which is powered off the main gear which also powers the main rotor.
The Swash Plate Assembly
The swash place on an RC helicopter is used to translate the pilots commands into the motion of the main rotor blades and / or fly-bar.
The swash plate assembly seats on to the main rotor shaft beneath the head of the heli and is made up of one rotating and one non-rotating disc.
The lower, non-rotating disc is connected directly to the cyclic and collective controls which are controlled by servos under the command of the pilot’s transmitter inputs.
This non-rotating disc is connected by a bearing to the second rotating disc, which turns with rotor and is connected to the main rotor blade pitch horns.
The swash plate can tilt in any direction according to the cyclic controls, or move up and down to change the pitch of the rotors with the collective control, which allows the pilot to control the RC helicopter in a 3-dimensions.
Collective Control
The collective raises the entire swash plate assembly as a unit. As the swash plate goes up or down, it changes the pitch of all rotor blades simultaneously and the same degree. This is known as collective.
Therefore, when the collective is increased, it will raise the entire swash plate assembly increasing the pitch. Increasing the pitch increases the lift of the main rotor, causing the heli to gain altitude, while decreasing the angle of attack decreases the lift.
Cyclic Control
The cyclic works by tilting the swash plate up or down and increasing the pitch angle of a rotor blade individually as they rotate, so the pitch on one side of the helicopter is greater than it is on the other.
As the pitch angle changes, the lift generated by each blade changes and this unbalanced lift causes the helicopter to tip towards whichever side is experiencing the least amount of lift.
This allows the helicopter to move in any direction around a 360-degree circle, including forwards, backwards, left and right or any direction in between.
For example, when the cyclic control is pushed forwards on your transmitter, the swash plate tilts forward increasing the angle of attack (and lift) in the rear of your helicopter which causes it to move forwards.
Because of the cyclic and collective pitch control of the main rotor blades and the pitch control of the tail rotor, your engine RPM and therefore the speed of the main rotor blades, can be kept at a constant rate allowing the helicopter to respond quicker.
Your radio transmitter handles all the mixing between cyclic and collective movement, so all you need to think about is which way you want your helicopter to fly, not angles of attack or swash plate tilting.
Now that you understand a little better how a RC helicopter works, please keep in mind all the basic rules of learning to fly a RC airplane apply’s to RC heli’s as well. So please check out the learning to fly section for more need to know information.
Also join a local RC helicopter or RC airplane club to get proper radio controlled helicopter training. They will be glad to give you some RC helicopter help.
This category is all about radio controlled helicopters. Before you venture into this topic, it is better to read all about the fixed-wing aircraft (i.e. an airplane) which is a prerequisite even on learning to fly or study full-size airplane. But on the contrary, many folks have skipped the fixed-wing and went straight to rotary-wing aircraft with success. Anyway it’s not that hard to learn all about helicopter and to fly them. Once I’ve read a book that described how hard is it to fly a helicopter, and it says “it’s like balancing a steel ball on a knife edge while riding a bicycle” sounds ridiculous, but there is some truth about the matter.
Thank goodness there are modern innovations to simpify the task of flying those complex machines. For example the gyoscope or stabilizers which are used to stabilized the tail rotor and computerized radio control equipments to mix the controls of main rotor variable pitch and tail rotor pitch. So then we will start our lesson as follows:
Chapter 1 : RC Helicopter Nomenclature
Chapter 2 : Why and How Helicopters Fly
Chapter 3 : Rotary Wing Stability and Control
Chapter 4 : Helicopter Weight and Balance
Chapter 5 : Helicopter Powerplant
Chapter 6 : Choosing My First Model Helicopter
Happy Hovering
Check Out These Heli Articles:
Getting Started With Your Remote Controlled Helicopters
5 Types of RC Helicopters- Check This Out Before You Buy.
I must say this again just to make sure you understand that remote controlled helicopters are one of the most dangerous models to fly. Before flying model rc helicopters please get rc helicopter training, join a rc club they will be glad to give you rc helicopter help. And become a member of the Academy of Model Aeronautics which will provide you with $2,500,000 in damage and injury insurance for only $58.00 per year.
Things to know before flying remote controlled helicopters
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helicopter radio controlled
