Aviation and the Global Atmosphere

Aviation and the Global Atmosphere
Aviation and the Global Atmosphere
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7.11. Special Military Considerations
Other reports in this collection
Although today's military and civil aircraft projects clearly respond to radically different national requirements, the underlying engine technology of the two types of
aircraft has a significant degree of commonality. This situation is not surprising in the case of the military transport aircraft engine: In common with the civil engine
requirements, large payloads must be carried over long distances at the lowest possible costs. The similarities are less obvious, however, with regard to combat
aircraft (including fighter/bombers), which have no clear civil parallels. Nevertheless, many of the technical advances that have been developed to meet the military
challenge have been adopted, in one form or another, in advanced civil engine applications. Indeed, an increasing number of examples of technical advances derived
from civil engine research also are relevant to military engines. This two-way exchange justifies the fact that a significant part of today's basic research underpinning
aero-engines for the future is supported directly or indirectly through military and civil engine sources (dual use).
Notwithstanding the parallel development paths and mutual objectives mentioned above, limits must be taken into account. In general terms, increases in the fuel
efficiency of combat aircraft are consistent with the logistics and operational needs of the military because aircraft with lower fuel consumption rates would be able to
remain engaged for longer periods of time, carry additional payload, reach targets from greater distances, or a combination of the three depending on operational
requirements. They would also require less in-flight refueling. However, the prescribed altitude for optimum fuel efficiency may not be not be appropriate for military
operations. Similarly, some of the restrictions on civil transport ground operations (e.g., engine start, taxi, and take-off procedures) may not be acceptable to military
users. Although military procurement officials and operators are now acutely aware of their responsibilities with regard to environmental effects, operational
effectiveness will always be the primary requirement. The following sections focus on military aero-engines-in particular on aspects of such engines that, for
performance and/or operational reasons, differ from their civil counterparts in ways that might influence emissions. It is important to rationalize these differences in
terms of their real impact on the environment by taking proper account of current and likely future proportions of the world's military aircraft fleet compared to the global
total of all types and operations of aircraft. Chapter 9 shows numerically how the environmental impact of military operations becomes a diminishing percentage of the
total of all aircraft operations as the effects of the anticipated strong growth of civil transport takes effect over the next 50 years or so. Differences between military
fuels-F-34 (NATO) and JP-8 (US)-and civil AVTUR/Jet A-1 fuel are covered in Section 7.7.
7.11.1. Differences Resulting from Operational and Design Features
7.11.1.1. Combat Aircraft
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