More often, UAVs were defeated by the immaturity of the available technology, changing needs, soaring costs and, above all, the successful development of rival technologies.

• 而更通常出现的情况是，无人机没能得到实际的运用，原因有很多，如现有科技的不成熟、需求不断变化、成本迅疾飙升，而最重要的是，对手的科技成果得到成功的发展。