Which part of the helicopter blades spin faster?

A second gearbox does the same for the tail rotor, although the tail rotor, being much smaller, can rotate faster than the main rotor.

How can the retreating blade produce as much lift as the advancing blade during forward flight?

When flapping, a rotor blade will travel upward during its advance, creating a lesser angle of attack (AOA) and therefore lesser lift. When the blade retreats, the blade falls downward again, increasing the AOA and therefore generating greater lift.

Do helicopter engines run at constant speed?

A helicopter in principle has a constant speed rotor. In fact, the allowed RPM range is very narrow, somewhere between 90-110\% nominal RPM. This RPM range is achieved either by a manual throttle or a governor.

How does helicopter fly forward?

This kind of directional flight is achieved by tilting the swash plate assembly with the cyclic, which alters the pitch of each blade as it rotates. As a result, every blade produces maximum lift at a particular point. The unbalanced lift causes the helicopter to tip forward and move in that direction.

How do helicopters fly up and down?

Unlike airplanes, helicopters feature spinning wings called blades or rotors on top. As a helicopter’s blades spin, they create a force called lift that allows the helicopter to rise into the air. For example, helicopters can move straight up or down and hover in the air without moving.

What is the wind speed and lift developed by the advancing blade in relation to the retreating blade?

Therefore, as a result of the relative wind speed, the advancing blade side of the rotor disc produces more lift than the retreating blade side. This condition is defined as dissymmetry of lift. See figure 5-4.

What is advancing blade concept?

The Advancing Blade Concept (ABC) is a relatively new type of helicopter rotor system that has been flight tested 67 hours. This would involve design and development of a lighter weight rotor system utilizing high-modulus material and redesign of the control system. …

What is the advancing blade side of a helicopter?

advancing blade side. A rotor blade that is moving in the same direction as the aircraft is called the advancing blade and the blade moving in the opposite direction is called the retreating blade. Balancing lift across the rotor disc is important to a helicopter’s stability.

Why do helicopter rotor blades flap forward?

In forward flight the advancing blade has a higher airspeed than the retreating blade, creating unequal lift across the rotor disc. A fuller treatment is provided in dissymmetry of lift . Most helicopter designs compensate for this by incorporating a certain degree of vertical “flap” movement of the rotor blades.

What happens to the advancing blade when the rotor stalls?

The advancing blade continues to generate lift, but the retreating blade enters a stall condition, usually resulting in an uncommanded increase in pitch of the nose and a roll in the direction of the retreating side of the rotor disc. In counter-clockwise rotating rotor systems (as in most American-made types) this is the left side.

What is the advancing blade and retreating blade?

It is a phenomenon that affects single-rotor helicopters and autogyros in forward flight. A rotor blade that is moving in the same direction as the aircraft is called the advancing blade and the blade moving in the opposite direction is called the retreating blade. Balancing lift across the rotor disc is important to a helicopter’s stability.