By Howard Slutsken, CNN

(CNN) -- Singapore to New York, nonstop. Almost 20 hours in the air.

By the end of this year, passengers on Singapore Airline's newest plane, the Airbus A350-900ULR -- for Ultra Long-Range -- will travel on a record-breaking, globe-spanning flight that will reconnect the two major metropolises.

The airline used to fly the gas-guzzling, four-engine A340-500 on the 9,500-mile route, with just 100 business-class seats on board. The service proved to be inefficient, and Singapore Airlines canceled the flights in 2013.

The airline is now taking delivery of Airbus' newest wide-body, the A350-900. It has 21 planes in its fleet, of an order for 67 aircraft.

Singapore Airlines has ordered seven of the ULRs.

On April 23, the plane had its first test flight, an almost five-hour round-trip that launched from the airframer's assembly plant in Toulouse, France.

The ULR will be able to fly a remarkable 11,160 miles, an increase of more than 1,800 miles over the standard A350. It means that Singapore Airlines will reclaim the crown of running the world's longest nonstop air route.

Day in the air

But how will passengers comfortably fly -- or perhaps endure -- a flight that lasts the better part of a full day?

That's three hours longer than the Qantas Airlines 787 flight from Perth to London experienced in March by CNN's Richard Quest.

"The A350 is a clean-sheet design that has been designed for those long-range flights," Florent Petteni, Airbus' Aircraft Interiors Marketing Director for the A350, tells CNN Travel.

All A350s share Airbus' design philosophy that makes the aircraft cabin feel more like a room, rather than a long tube. The plane has high ceilings, sophisticated LED lighting, almost vertical sidewalls and a low noise level.

These features, along with a maximum in-cabin simulated altitude of just 6,000 feet, all combine to provide an improved passenger experience, according to Petteni.

"You may not exactly pinpoint why it's so comfortable and so nice to be flying on this airplane, but everything was done on purpose."

Like the windows.

A room with a view

The A350's fuselage is made from composite materials, including carbon fiber -- rather than using conventional aluminum construction techniques. This allowed Airbus to include wide, panoramic windows. Lots of windows.

"We have no missing windows. Whenever a passenger selects a window seat, they will always get a window," says Petteni. This eliminates the dreaded "windowless" window seat found on other aircraft.

But given the ultra long-range mission of the ULR, it was equally important to ensure that the cabin can be made fully dark, to give passengers a restful sleep environment.

Airlines will have the choice between a standard pull-down shade, or an electro-mechanical, push-button system, with two cabin-darkening blinds.

The air circulation system on the A350 has also been designed to be quiet and draft-free.

"So even though we recycle the air in the full capacity of the cabin every two to three minutes, we do it in a way that we reduce the velocity of the air inside the cabin," says Petteni.

Fill 'er up

Compared to the standard A350-900, the ULR will haul an additional 24,000 liters of fuel to fly its 20-hour missions.

Along with the stretch A350-1000, the family of planes shares basically the same wing structure. That structure includes a common-sized center fuel tank.

"All that we are doing on the ULR is to use all of the volume that we have in the center tank, a bit more than the usage that we have for the -1000," explains Marisa Lucas-Ugena, head of A350 marketing.

"We put in additional pipes and drains so that we can get usage of the entire volume. For the [standard] -900 we're not using the entire space that we have."

That additional fuel weighs about an extra 20,000 pounds. And just like any other aircraft, the ULR's operators will have to trade on the payload/range equation.

If you want to fly far, you must carry more fuel. That fuel adds more weight, so you must then reduce the rest of the payload.

A manufacturer could increase the maximum take-off weight (MTOW) of the plane, the airline could limit the number of passengers or amount of cargo carried, or there could be a combination of both.

Airbus has upped the ULR's MTOW to 280 tonnes, 5 tonnes more than the standard airframe.

Singapore Airlines will announce the interior configuration of its ULRs sometime soon, but it's expected that there will be far fewer than the 253 seats in the airline's standard A350-900s.

There will likely be a large business-class cabin, and perhaps a number of premium economy seats.

In addition to the fuel system changes, the ULR sports a host of aerodynamic updates, include longer version of the A350's elegant winglets.

Call of nature

No matter the number of people on board, Airbus feels sure that the ULR's lavatory and water systems are up to the challenge of a 20-hour flight.

"There are no changes to the capacities, just optimization," explains Lucas-Ugena. "That's something that we do at Airbus, when we have a family of airplanes, any time we have a new type or a new modification, we take the opportunity to improve things."

Perhaps another Airbus concept will find its way into the ULR.

At the recent Aircraft Interior Expo in Hamburg, the company, along with aircraft interiors manufacturer Zodiac Aerospace, unveiled a proposal for "Lower Deck Modules" that would feature sleeping quarters for passengers.

Located in the space normally filled with cargo containers, passengers would access bunk beds via a stairway from the main deck.

Sweet dreams.