The super plane so far only codenamed 'X-48C' is the brainchild of the US space agency NASA which is developing it in collaboration with aviation major Boeing.
NASA said it has successfully demonstrated a working prototype and took a scale replica for a 'test-fly', the agency said in a statement.
But the aircraft which NASA hopes will become a dominant design within the next 20 years, may come as disappointment for travellers who insist on window seats.
The triangular plane sacrifices window seats for increased capacity and higher fuel efficiency.
NASA engineers said that test flights on the aircraft built in UK would continue throughout 2012.
The new X-48C is a 'hybrid-winged body' plane which offers more internal volume for passengers and cargo and the triangle shaped plane is reminiscent of spy planes, which cuts through the air more efficiently.
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NASA conceits that the plane could be developed in the next 15-20 years for potentially consumer flights as well as for military applications.
The X-48C retains most dimensions of the earlier models, with a wingspan just longer than 20 feet, and a weight of about 500 pounds (227 kilogramme). The aircraft has an estimated top speed of about 140 mph (225 kph), and a maximum altitude of 10,000 feet.