คู่เดียวตรงเป๊ะ23..ชุดเดียวบนล่าง มาแล้วตามได้แล้ว2/5/62
The United States Navy and the Coast Guard, as well as the Marines, Army and Air Force desperately need a reliable vertical takeoff and landing UAV. Usually this is performed with turbo-fans, or rotor blades. The problem with rotor blades is generally it limits the speed of the vehicle due to certain aerodynamic characteristics.
from: http://ezinearticles.com/?We-Need-a-UAV-Based-on-the-New-Sikorsky-X2-Project---Let-Me-Explain&id=5255790
