A cargo aircraft (also known as freight aircraft, freighter, airlifter or cargo jet) is a fixed-wing aircraft that is designed or converted for the carriage of air cargo, rather than passengers. Such aircraft usually do not incorporate passenger amenities, and generally feature one or more large doors for loading cargo. Freighters may be operated by civil passenger or cargo airlines, by private individuals or by the armed forces of individual countries (for the latter see military transport aircraft).
Aircraft designed for cargo flight usually have features that distinguish them from conventional passenger aircraft: a wide/tall fuselage cross-section, a high-wing to allow the cargo area to sit near the ground, a large number of wheels to allow it to land at unprepared locations, and a high-mounted tail to allow cargo to be driven directly into and off the aircraft.
Derivatives of non-cargo aircraft
Existing air cargo derivatives of passenger airplanes have been very fitting. For example, the Boeing-747-200F has proven to be the big payload toiler of the air cargo fleet and could continue unmodified for a number of years. Each derivative freighter has the benefit of having most of its development costs already assessed against the transaction of its passenger equivalent. Furthermore, the financial arrangements for buying the airplane have already been established and there is a quite short lead time before production (as compared to all new aircraft). A main drawback of existing air cargo aircraft is that they represent older technology; thus their direct operating costs are higher than what might be achieved with current technology. Additionally, since they generally have not been designed specifically for air cargo, loading and unloading can cause problems; the aircraft may be pressurized more than necessary, and there may be apparatus manufactured for passenger safety that is not necessary for cargo.
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.
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