China is developing a large twin-fuselage turbofan-powered UAV that could operate at altitudes up to 80,000 feet. It is known as Divine Eagle (also Project 973 or Shen Diao in Chinese). Its uses may include naval missions like the Global Hawk's Triton derivative (published ceiling 60,000 feet). The bus next to Divine Eagle appears to have been provided for scale. (Photo above and some details courtesy Air Force World July 4, 2015).
As at mid 2015 Divine Eagle was undergoing flight tests. Divine Eagle may be a development of Russia's S-62 UAV concept.
Submarine relevance is that Divine Eagle could loiter over contested South China and East China seas for 30+ hours with the ability to detect submarine snorkels by using cloud penetrating radar and electro-optical sensors. Divine Eagle is large enough to carry lightweight torpedoes for powered flight then torpedo mode. Divine Eagle could also act as part of a ASW chain using China's numerous small ballistic missiles, cruise missiles, ASW aircraft, ships or Chinese submarines.
Divine Eagle's snorkel spotting capabilities means submarines in the South China Sea should, of course, be built for longer fully submerged range between snorts.
It is suggested Divine Eagle could also mount a large metre-wave antennae between the fuselages for counter-stealth missions against stealthy UAVs (eg. the RQ-170), cruise missiles, B-2 bombers, F-22s and F-35s.
Satellite picture of Divine Eagle large UAV next to that bus again. (Courtesy bellingcat August 23, 2015).
Divine Eagle's probable length may be 14 to 18 meters and wingspan 40 to 50 meters. It may weigh up to 15 tons, just over Global Hawk's 14.5 tons with the heavier weight perhaps for oneupmanship-propaganda reasons.
Divine Eagle may operate from China's Sanya naval base on Hainan Island to cover the South China Sea. Naval air bases China is building on several islands (including Fiery Cross and Mischief Reefs (map above)) may provide emergency landing runways for Divine Eagle. Of course China's new South China Sea airfields would be principally used by aircraft (ASW, fighter-bombers, troop transports) and UAVs of shorter range.
Submarine Matters will provide much more detail and maps later this week on China's construction of small naval and air bases on South China Sea reefs.