Tail And Headwinds

In 2015, a 777-200 made the Newyork-London route in 5 hours,16 minutes where the usual journey time is ~7 hours.

The flight reached ground speeds of up to 1200 km/h (745 mph),riding a powerful jet stream of up to 322 km/h (200 mph) tailwinds and breaking the sonic barrier ( 1224 km/h (761 mph)).

Tail and headwinds

The principle is analogous to those high school problems in relative velocity:

“A man rows a boat in a river. The velocity of the boat is … Find the stream velocity”

If you are headed downstream i.e in the same direction as the river stream you will reach your destination faster than if you were rowing upstream.

Similarly a tailwind is one that blows along the same direction of the aircraft increasing the net speed of the aircraft ,and headwind is one that blows in the opposite direction and slows the craft down.

So, does this mean that if you are moving at v kmph and there is a headwind of -v kmph, you would just hover? Hell yeah!

Take a look at this video:

Wind shear

A phenomenon known as ‘wind shear’ occurs when the wind speed changes abruptly, which can cause turbulence and rapid increase/decrease in velocity of flight.

This can be really challenging during landing since if the headwind turns tailwind, there is a possibility of the aircraft overshooting the runway due to the increased velocity.

What causes this ?

The aviation industry takes advantage of trade winds and jet streams in order to cut time off the flight and save fuel.

Tradewinds are caused by the unequal heating of the atmosphere at different latitudes and altitudes and by the effects of the Earth’s rotation (Coriolis effect).

Trade wind pattern. Credit: Earth Wind Map

Jet streams on the other hand are this narrow current of fast moving winds in the upper troposphere flowing west to east. And riding one can definitely make your travel time shorter.

Jet streams in the northern hemisphere

As a result of jet streams, within North America the time needed to fly east across the continent can be decreased by about 30 minutes if an airplane can fly with the jet stream, or increased by more than that amount if it must fly west against it.

How do pilots know about this ?

Pilots receive a weather briefing actively during flight. Included in the briefing is the best combination of jetstreams and other wind patterns that the pilot can take advantage of saving time and fuel.

Many airports have runways facing in different directions in order to allow the pilots to use the runway that faces the wind during take off/landing.

Have a great day!

Absolute Unit

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iphleandro-blog

6 years ago

Sellos

Se utilizaban para estampar diseños sobre materiales perecederos como la tela y el papel o para decorar cerámica.

INAH

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iphleandro-blog

7 years ago

These Geometric Tarts Turn Patisserie Into Architecture.

Pastry chef Dinara Kasko uses sheets of chocolate to create stunning edible treats. See more at Dinara Kasko | José Margulis.

Ultra-thin sheets of chocolate are transformed into topographic works of art that taste just as good as they look. The project is a result of a collaboration between architect-turned-pastry chef Dinara Kasko and Miami-based artist José Margulis.

Margulis, who works with geometric abstractionism and kinetic art, created the initial patterns of what would eventually become edible sheets of chocolate using colorful 3D plastic sheets. Margulis focused on curved shapes with various volumetric geometries, transparencies and intense colors to create a rich, layered effect.

“Margulis’s utmost concern is the creation of geometric shapes conceived mostly by changing the perspective of the viewer accompanied by the philosophical notion that everything in life has diverse levels of narrative and spatial perceptions,” wrote Kasko in a blog post.

The chef then took Margulis’s initial designs and transformed them into edible treats using various cutting machines and tools to create 3D chocolate layers. These layers were then placed on top of four different flavored tart cakes, including blackberry-blueberry and cherry confit almond sponge cakes.

“I was transforming the object of art into something edible that would later perish, while emphasizing the ephemeral art, its fleetingness in our life,” said Kasko. “The appearance and, of course, the taste should leave a lasting impression and expand observer’s boundaries of what ‘cake’ can be. I like to surprise people.”

Shared from MATT VITONE at psfk.

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