All of the training and reference material will be based on the FS2002/FS2004 default Bell 206 JetRanger aircraft, unless otherwise specified.

How a helicopter flies.

We are going to skip all of the cliches and analogies often used to describe how a helicopter flies, or how they behave in relation to fixed wing counterparts. We will start by saying that Helicopters are undoubtedly the most complex flying machines ever created...period. Helicopters have amazing and unique flying capabilities, but they come at a price of mechanical complexity, fuel inefficiency, reliability, and maintainability. It is best when learning how a helicopter flies, to treat the helicopter as a unique flying machine, and NOT as a derivative of the fixed wing aircraft.

After understanding some of the basic principles behind helicopter flight, you'll hopefully have a new appreciation for how these wonderful machines work.

Yaw, Pitch, and Roll

Hopefully you are already familiar with these three axes of flight, if not here is a refresher. Pretend your head is a helicopter and do the following:
1. Keeping your head level, look right, then look left. That's yaw.
2. Look up at the ceiling and then look down at the floor. That's pitch.
3. While looking forward, cock your head to the left, and then to the right. That's roll.

Main rotor disc and lift.

When the main rotor is spinning it creates what is referred to as a "rotor disc", when the blades are set at a position to bite into the air (like a fan) using a flight control called the "collective", this rotor disc begins to create lift. The thrust of this lift generally travels in a direction that is perpendicular to the rotor disc. If the helicopter is sitting level on the ground, and the rotor disc is also level, the thrust is being directed straight down. If the blades where to bite into the air enough, the amount of lift being produced would overcome the weight of the aircraft, and the helicopter would begin to lift off, straight up.



Directing Main Rotor Thrust.

Now that we can visualize the main rotor disc producing thrust in a straight downward direction, we can tilt the rotor disc (the helicopter will follow) in order to convert some of that upward force (produced by downward thrust) into forward force. The more we tilt the disc forward, the more forward pointing thrust we will gain, and the less thrust will be available to force the helicopter upward. The helicopter will gain speed forward, but will begin to lose altitude. To counteract the drop in altitude, we will either have to level the rotor disc once again, or increase the overall power and bite of the blades. It is important to understand that this thrust can be directed in any direction (forward, rear, left, or right) using the flight control called the "cyclic" or the "stick", so that increasing velocity in any direction becomes possible. Not necessarily safe, but possible.



Tail Rotor, Anti-torque.

As the main rotor spins, it causes the rest of the helicopter (connected to the rotor disc by the main rotor shaft) to spin with an equal amount of force in the opposite direction. To counter-act this force, the tail rotor produces thrust that pushes against the helicopters spinning motion. The amount of force produced by the tail rotor is controlled by use of the anti-torque pedals at the pilot's feet. In a hover, or at low speeds, the pilot can use controlled variations in the tail rotor thrust to spin the helicopter right or left on the yaw axis.



Full Forward Flight

As the helicopter gains forward velocity, air moving over the vertical stabilizer at the rear of the aircraft will begin to increase its effectiveness. Eventually the use of the anti-torque pedals in order to keep the helicopter aligned to a particular heading will be unnecessary. The helicopter does not have a controllable rudder; instead turns at high speeds are performed using a coordinated amount of roll and pitch.

Translational Lift and Ground Effect

As a helicopter lifts off the ground into a stationary hover, its main rotor blades have to work extra hard to produce lift, because the air they are turning through is turbulent due to the blades themselves. Translational lift will occur as the helicopter begins to move forward and begins transitioning to forward flight (around 40kts), the blades begin hitting smooth undisturbed air and start to produce more better lift. A slight "bucking" occurs as the front of the spinning rotor disc creates more lift than the rear.  Ground effect occurs when the rotor disc is producing thrust in the direction of a hard smooth surface such as a paved helipad. Because the thrust hits against a hard surface, it is more effective than if the thrust is hitting nothing or a soft surface such as long grass.

Helicopter Limitations

The most notable limitations that helicopters face are max cruising speed and useful range. High cruising speeds are impossible for helicopters due to the fact that as the main rotor blade spins it is affected by dissymmetry of lift. Dissymmetry of lift simply means that as the helicopter moves forward at high speeds, the forward moving blade gets more and more lift, while the blade travelling toward the rear of the aircraft gets less and less. This has been partially countered in newer helicopter designs by allowing the rotor blades to flex vertically as needed, however for most helicopters it still limits their max cruising speeds to the less than 200kts. Useful range is also a challenging factor in all helicopter designs. Because helicopters require so much power to lift, their fuel payload and consumption rates are major design considerations. Because the power to weight ratio of a helicopter design is so crucial, and fuel is so heavy, their ranges are often limited compared to fixed wing aircraft.