Contents
How are helicopter blades controlled?
These blade pitch variations are controlled by tilting, raising, or lowering the swash plate with the flight controls. The vast majority of helicopters maintain a constant rotor speed (RPM) during flight, leaving the angle of attack of the blades as the sole means of adjusting thrust from the rotor.
What causes a helicopter rotor blade to throw off pitch?
The first is the main rotor pitch change links (PCL). The PCL controls the angle of each main rotor blade individually. As the blade pitch is increased, drag is increased, causing the blade to lag. If the blade pitch is decreased, drag is decreased, causing the blade to lead.
Do helicopters have electric motors?
It has been called the world’s “first all-electric helicopter”. The Firefly is a modified Sikorsky S-300C helicopter with its engine replaced by an electric motor and two lithium-ion battery packs. The helicopter can hold only the pilot, no passengers, and operate for 12 to 15 minutes.
Can helicopters fly without electricity?
Unlike a plane, which can glide a large distance with no power, a helo has no way to slow down—or so the thinking goes. Actually, helicopters have a built-in mechanical control called the collective pitch lever that allows them to descend slowly and land even if the engine dies. This maneuver is called autorotation.
How does the speed of a helicopter affect the blade pitch?
However, in a helicopter, the rotor is nearly aligned to the airflow. The vertical ‘chunk’ of air the rotor takes therefore does not increase that much with increasing speed. At the same time, due to the forward speed the helicopter gains translational lift, which would actually decrease the blade pitch required.
How are the rotor blades of a helicopter tilted?
With the rotor blades rotating around a vertical mast, the total lift vector of the rotor is vertical and the helicopter hovers. If a translation is desired, this vector must be tilted so that an horizontal component can appear. This is done by tilting the rotor disc.
What causes a helicopter to lose its rpm?
This is usually initiated by exceeding MAP (Manifold Pressure) or torque due to the pilot dialling in too much collective. Ultimately resulting in rpm decay, so much so that the blades exceed their ability to produce lift and stall, no matter how much more power you apply.
What causes a blade stall in a helicopter?
An “Under speed” or “Blade Stall” is when the pitch is too high to produce lift. This is usually initiated by exceeding MAP (Manifold Pressure) or torque due to the pilot dialling in too much collective.