He is also ordering further tests into vortex ring state.

The object is then pulled out, creating a vortex ring.

Further acceleration leads to a growth of the vortex ring.

That phenomenon, known as vortex ring state, can occur with any helicopter.

Because of the way they rotate, a vortex ring can hold itself together and travel for quite a distance.

This applies, in particular, to the formation and motion of vortex rings.

But they also made 28 recommendations to address the problem of vortex ring state and other aerodynamic issues.

They also developed the idea of quantum vortex rings.

Dye may be used to seed the drop so as the vortex ring is made visible.

They pause between the contraction and expansion to create two vortex rings.

By doing so, the second vortex ring rolls under it and begins to spin faster.

Vortex ring toys have been described as home-made projects since at least the 1970s.

The vortex ring struck harmlessly against the screen, was absorbed by it.

A vortex ring can also be created by a spinning propeller, as in a blender.

The formation, motion and interaction of vortex rings have been extensively studied.

And a Pentagon report released last month recommended further testing to diagnose vortex ring state.

Thus, a vortex ring can carry mass much further and with less dispersion than a jet of fluid.

He sent a single small vortex ring.

Velocity, momentum and energy of vortex rings attached to objects are studied in detail.

Fiery vortex rings are also a commonly produced trick by fire eaters.

If altitude permits, autorotations may also be used to recover from vortex ring state.

From inside the cave a great puff of black smoke came hurtling out in a perfect vortex ring.

The net result is a poloidal flow in A that evolves into a vortex ring.

Devices have been invented which generate bubble vortex rings.

That configuration caused the Osprey to flip over when it entered vortex ring state, experts have said.