Other Tianjin projects are extending the gliders' endurance. The Dragon has a fuel cell rather than lithium batteries, with perhaps a mission duration measured in years. Another Tianjin glider will have a 'temperature difference engine.' This is similar to the prototype thermal glider pioneered by Teledyne Webb, which extracts energy from the temperature variation between sea water layers at different depths. It has the potential to power a glider indefinitely.

Researchers at Northwestern Polytechnic University at Xian are improving glider agility by giving them wings that can move independently. The researchers claim this design is faster and more efficient than fixed-wing gliders, as well as more maneuvrable.

A second Xian project takes the idea further, with flapping wings that act like a turtle's fins to provide extra propulsion. This model is now starting laboratory trials. China excels in the field of “robotic fish” with flapping fins. Gliders incorporating this technology could put on a burst of speed without compromising stealth, while retaining glider endurance for long missions.

The U.S. is carrying out R&D in many of the same areas, though not at a rapid pace; comparing the two is difficult. There may be more research in China not in the public domain. Papers from “No. 710 R&D Institute,” a facility at Yichang that carries out military research, mention studies of an underwater glider big enough to carry weapons. This would represent a dramatic new sea denial capability.

However, the Chinese have yet to prove that they can translate any of their advanced glider technology programs into a finished product that can outdo designs from the West.

“There has not been any Sputnik moment yet,” says Goldstein.

Goldstein warns that it's too early to say whether the Chinese navy will commit itself to gliders on a large scale. But while the progress of a new aircraft carrier or nuclear submarine under construction can be tracked over years, new gliders could be built rapidly and in secrecy in large numbers, and they are difficult to spot even when deployed. That Sputnik moment might yet arrive.