What is blade tip vortex?

A blade vortex interaction (BVI) is an unsteady phenomenon of three-dimensional nature, which occurs when a rotor blade passes within a close proximity of the shed tip vortices from a previous blade.

What causes a vortex ring?

The cause of true Vortex Ring is two-fold. In all flight circumstances there is a degree of airflow circulation at the tips of the blades where the air forced downwards aerodynamically rotates around the aerofoil tip and forms a vortex; this happens with all aerofoils including fixed wing aircraft wings.

How does a helicopter blade spin?

The blades are shaped like airfoils (airplane wings with a curved profile) so they generate lift as they spin. Each blade can swivel about a feathering hinge as it spins. Vertical pitch links push the blades up and down, making them swivel as they rotate.

Can a helicopter hover in one place?

A helicopter can hover in place for as long it has the power required and the fuel to keep the engines running. The length of time depends on the type of helicopter, the efficiency of the engines and main rotor system, as well as the kind of hover a pilot wants to hold.

How do vortex rings work?

A toroidal, or doughnut-shaped, vortex is formed when fluid flows back on itself, making a spinning ring around an invisible core. When a fluid flows quickly the pressure drops, so as the vortex spins its pressure relative to the water that surrounds it is lowered.

How are helicopter blades made?

Starts here4:30How It’s Made Helicopter – YouTubeYouTube

How do helicopter blades create lift?

In most cases, the lift for an aircraft is created with its wings. For a helicopter, a lift is generated by the way the main rotor blades are formed so the air is pushed in a downward movement when the blades spin. As the air pressure changes, the helicopter lifts up.

How long can a helicopter fly?

So How Far Can Helicopters Fly? Only a few people know that helicopters can fly for an extended period or a considerable far distance before they need to stop or to refuel. Typically, before helicopters can stop and refuel, it can actually fly for about 2.5 to 5 hours or travel for about 250 miles.

How long can a helicopter stay still in the air?

A helicopter can hover in place for as long it has the power required and the fuel to keep the engines running. While how long this is depends on several factors, the longest time a helicopter has ever hovered is 50 hours and 50 seconds.

What is the vortex ring state in a helicopter?

Turbulent airflow results and loss of rotor efficiency. If allowed to continue, uncommanded pitch and roll oscillations may occur, with a large descent rate. The vortex ring state, also known as settling with power, is a dangerous condition that may arise in helicopter flight, when a vortex ring system engulfs the rotor causing severe loss of lift.

What happens when a helicopter stall?

As the inner blade sections stall, a second set of vortices, similar to the rotor tip vortices, form in the center of the rotor system, and combined with the outer set of vortices, result in severe loss of lift. The failure of a helicopter pilot to recognize and react to the condition can lead to high descent rates and ground impact.

What are the factors affecting vortex ring state?

Frame design, size and power affect the likelihood of entering the state and recovering from it. Multirotors that do not have altitude hold are also more likely to succumb to operator error, where the pilot drops the craft too fast resulting in the upwash at the rotor hubs that can lead to vortex ring state.

Is “settling with power” the same as vortex ring?

Quote: There are some uninformed pilots who use “settling with power” to describe vortex ring, in fact some publications use the terms interchangeably. Confusion results when symptoms are related that do not describe true vortex ring but rather describe “settling with insufficient power”.