An airplane which typically seats 300 passengers is going ULR just as Boeing 787 could go ULR by cutting the seat count by half and adding 6,500 gallons of fuel capacity.
It then went and redesigned its wing making it more like a Boeing 787 crafted wing for efficient flight. Having no newer of more efficient engines, but less weight via having fewer passengers and a new wing. If calculating a passenger load for any long-range aircraft, it must start with a mass of 300 lbs per seat which includes the following: seat weight, airline supplies, passenger weight, additional crew, and luggage.
The A350-900 ULR must come to a Passenger Weight Reduction (PWR) by calculating the typical A350-900 passengers load of (306 passengers x's 300 lbs) and then subtract the PWR of (144 seats x's 300 lbs) as ULR has passengers charted. Thus equaling a Passenger Weight Reduction (PWR) of about 150 lbs per passenger per load.
Otherwise, it trims off the paying load by 300 (lbs) X's 144 passengers or 27,500 lbs. The net PWR is calculated by factoring its initial PW factor weight of 300 lbs for 91,800 lbs (A-350-900 seat number x's 300 lbs) - 46,800 (using a ULR seat number x's 300) or equaling about 27,500 lbs. The fuel increase weight of 6,500 lbs on a URL is factored from Jet A gallons equals about an additional 44,000 lbs calculated, increasing its range to about 9,500 miles from 8500 miles.
The ULR configuration increases passenger space by only allowing only 94 economy and 68 business class seats spread out over its elongated body. It's truly becoming a space-ship.
Qantas Airline has configured a standard Boeing 787-9 going the distance from Perth Australia to London England for 9,100 miles, by only seating 236 passengers but not adding an additional fuel capacity or wing upgrade. Project Sunrise from the Qantas concept has asked both airframers to come up with a solution for its own aspirations of going anywhere in Australia to anywhere in the world.
An example is the Perth to London route by it would also like using a Sydney to London proposition so passengers would not need a connecting flight to Perth from Sydney or Vice versa when going to New York City. Those are goals of Qantas but not necessarily of airline fleets found around the world. The ULR has about 67 ordered to date including Singapore Airlines order book. Its own goals have formed a strategy going east or west anywhere in the world.
Project Sunrise will create spaceships coming from both Boeing or Airbus traveling for 20 hours using a lower number of passenger capacity coming from both designs but will become an expensive proposition for everyone concerned.