The latest unmanned aircraft pictures from China have revealed a new UAV with joined wing and tail that could considerably increase range and payload and produce better handling at high altitudes. The unmanned aircraft may be undergoing near-field radar-cross-section or antenna testing since Internet images show it on the ramp with the landing gear shrouded.
U.S. analysts are already suggesting that the new Chinese UAV design -- with its 60,000-ft. cruising altitude, 300-mi. radar surveillance range and, possibly, lower radar reflectivity if made from the right composites -- could serve as the targeting node for China’s anti-ship ballistic missiles.
Boeing used a joined-wing configuration in its contribution to the USAF Research Laboratory’s SensorCraft project, aimed at developing an aircraft capable of carrying an airframe-integrated, 360-deg.-coverage, high-resolution radar and remaining on station for 30 hours at 2,000 nm range. A small, low-speed free-flight model known as VA-1, with a 14-foot wingspan, was completed by AFRL in 2003 and test-flown. A model of Boeing’s Joined Wing SensorCraft was tested last year in NASA Langley’s Transonic Dynamics Tunnel under the USAF’s Aerodynamic Efficiency Improvement (AEI) program.
The new Chinese UAV was likely photographed on the Chengdu Aircraft Corp.’s ramp. Photographs emerging from Chinese Internet sources show a new design featuring a novel joined-wing layout. In the same size class as the General Atomics-Aeronautical Systems Inc. Avenger, and powered by a single turbofan engine, the new UAV is the most advanced Chinese design seen to date and the largest joined-wing aircraft known to have been built.
The company also makes the J-10 strike fighter, the J-20 stealth fighter prototype and a Global Hawk-like maritime reconnaissance UAV called the Xianglong or Soaring Dragon, which flew in December 2009. CAC officials say it has a wingspan of 75 ft., 45-ft. length and a cruise altitude of 55,000-to-60,000 ft., Chinese sources credited it with a 7500 kg (16,500 lb) take-off weight and 3800 nm range. The forebody is bulged to accommodate a high-data-rate satcoms antenna.
Joined wings – a subset of closed-wing systems – comprise a sweptback forward wing and a forward-swept aft wing. In the new Chinese UAV, (as in many such configurations,) the rear wing is higher than the forward wing to reduce the impact of the forward wing’s downwash on the rear wing’s lifting qualities. The rear wing has shorter span than the front wing and its downturned tips meet the front wing at a part-span point.
Advocates of the joined wing claim that its advantages stem from the fact that the front and rear wings are structurally cross-braced. This allows higher aspect ratio while keeping down weight and staying within flutter limits. Higher aspect ratio reduces drag due to lift, and because the wings are both slender and short-span (relative to a single wing with equivalent lift) the wing chords are short, which makes it easier to achieve laminar flow. The joined wing can also reduce trim drag.
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