China's internal pipeline of military aircraft demonstrators has produced yet another new and intriguing specimen as pictures posted on Chinese discussion forums revealed the nation's first tailless, unmanned and partially stealthy aircraft, apparently being readied for a debut flight test.
Chinese military watchers identify the aircraft as the Lijian - or "Sharp Sword" unmanned combat air vehicle (UCAV) demonstrator - calling it the product of an industrial collaboration between Hongdu, a maker of military jet trainers, and Shenyang, one of two major suppliers of frontline fighters to the Chinese air force and navy.
The size and shape of the pictured aircraft recalls the dimensions of such advanced Western designs as the Boeing Phantom Ray, Dassault Neuron, Lockheed Martin RQ-170 and Northrop Grumman X-47B.
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Unlike its flying wing cousins in the West, however, the Lijian does not appear designed for reduced visibility to radar in all aspects: the nozzle of a large, possibly afterburning, jet engine lies exposed and unshrouded on the aft fuselage, an easy target for detection by radar. Similar limitations appear on all of China's purportedly stealthy aircraft released to date, including the Chengdu J-20 and Shenyang J-31.
At the same time, the pictures reveal new and spectacular advances in the sophistication of Chinese aircraft designs. By making the Lijian a flying wing and tailless, China pronounces itself ready to tackle one of the hardest problems in aerodynamics and flight controls.
Flying wings are a holy grail for aerodynamicists seeking to optimise lift, and for electromagnetic frequency experts seeking to minimise the structural corners that are easy reflectors of radar waves.
However, the shape also produces aerodynamic effects that are difficult to control, such as a phenomenon called "pitch tumble" at very low airspeeds in which the aircraft loses control by suddenly flipping on to its back in an unrecoverable state.
Chinese industry has been focusing on the problems of tailless, flying wing designs for several years. Shenyang engineers, for example, published an academic paper in 2007 entitled Application of Flying Wing Configuration to UCAV for Reconnaissance, which concluded that such a tailless design is "an optimal selection" for aerodynamic purposes.
In 2011, Shenyang University also hosted a "mega-festival" for unmanned air vehicles, with researchers flying dozens of subscale UAVs in a quest to win cash prizes. One radio controlled UAV entered by Shenyang featured a 2m-wingspan (6.5ft) flying wing with a triagonal engine inlet, bearing at least a family resemblance to Lijian.
Source: Flight International
