aircraft. The main advantage of the dedicated air freighter is that it can be designed specifically for air freight demand, providing the type of loading and unloading, flooring, fuselage configuration, and pressurization which are optimized for its mission. Moreover, it can make full use of NASA's ACEE results, with the potential of significantly lowering operating costs and fuel usage. Such a high overhead raises the price of the airplane and its direct operating cost (because of depreciation and insurance costs) and increases the financial risks to investors, especially since it would be competing with derivatives which have much smaller development costs per unit and which themselves have incorporated some of the cost-reducing technology. Joint civil-military cargo aircraft One benefit of a combined development is that the development costs would be shared by the civil and military sectors, and the number of airplanes required by the military could be decreased by the number of civil reserve airplanes purchased by air carriers and available to the military in case of emergency. There are some possible drawbacks, as the restrictions executed by joint development, the punishments that would be suffered by both civil and military airplanes, and the difficulty in discovering an organizational structure that authorizes their compromise. Some features appropriate to a military aircraft would have to be rejected, because they are not suitable for a civil freighter. Moreover, each airplane would have to carry some weight which it would not carry if it were independently designed. This additional weight lessens the payload and the profitability of the commercial version. This could either be compensated by a transfer payment at acquisition, or an operating penalty compensation payment. Most important, it is not clear that there will be an adequate market for the civil version or that it will be cost competitive with derivatives of passenger aircraft. Unpiloted cargo aircraft Rapid delivery demand and e-commerce growth stimulate UAV freighters development for 2020: Californian Elroy Air wants to replace trucks on inefficient routes and should fly a subscale prototype; Californian Natilus plans a Boeing 747 sized transpacific unpiloted freighter and should fly a subscale prototype; Californian Sabrewing Aircraft targets small regional unpiloted freighter and should fly a 65%-scale vehicle in 2018 fall; The Chinese Academy of Sciences flew its payload AT200 in October 2017 based on New Zealand's PAC P-750 XSTOL utility turboprop Chinese package carrier SF Express conducted emergency logistics tests in December