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Assessment of Wingtip Modifications to Increase the Fuel Efficiency of Air Force Aircraft (2007) / Chapter Skim
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1 Background and Overview
Pages 12-17

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From page 12...
... .4 Broadly speaking, the fuel economy of an aircraft can be thought of as having three components: the efficiency of the engines, the aerodynamic 1Ron Sega, 2006, "Air Force energy strategy," Worldwide Energy Conference and Trade Show, Arlington, Va., April 19. 2Data provided by Defense Energy Support Center (DESC)
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From page 13...
... An example of such a wingtip modification is the "winglet" now seen on many commercial jet aircraft and some military aircraft, shown in Figure 1-1; however, many other aerodynamic improvements are possible. The concept of winglets was originally developed in the late 1800s by British aerodynamicist F.W.
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From page 14...
... -- aircraft manufacturers and winglet retrofit companies have reported that winglets also offer higher operating altitudes, improved aircraft roll rates, shorter time-to-climb rates, lower takeoff speeds, and less takeoff noise. In the commercial world, winglets have not only reduced fuel costs but have also increased operational flexibility by, for example, bringing new international destinations within range and increasing payload capability at airports at high altitudes or with shorter runways.
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From page 15...
... that can have a similar impact on fuel economy and aerodynamic performance. Thus, in this report, winglet denotes the traditional, nearly vertical wingtip design, while "wingtip modifications" will be used to refer to the more general set of wingtip designs, including winglets and wingtip extensions, aimed at reducing aerodynamic drag.
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From page 16...
... By also estimating the potential fuel savings and the number of these aircraft, the committee performed preliminary NPV calculations to calculate whether wingtip modifications for selected military aircraft would pay for themselves well before the aircraft are due to be retired. Recognizing that the cost of fuel delivered to the location where it is used may be many times higher for military aircraft than for commercial aircraft,11 the committee treated fuel cost as a parameter that could be varied over a large range.
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From page 17...
... This is followed by a qualitative analysis of the relative costs and benefits of retrofitting wingtip modifications on these aircraft, as well as a discussion of appropriate strategies the Air Force should use to maximize its fuel economy investments. Additional methods that might be considered by the Air Force to improve fuel economy, such as other aerodynamic changes, improving maintenance and operations, and reducing unnecessary weight, are discussed in Appendix B
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Key Terms

  • tip extensions
  • span extensions
  • wingtip extensions
  • fuel savings
  • fuel costs

  • military aircraft
  • wingtip span
  • fuel cost
  • fuel economy
  • force aircraft

  • aerodynamic performance
  • flight operations
  • retrofitting wingtip
  • treated fuel
  • potential fuel

  • vehicle fuel
  • improve fuel
  • vertical wing
  • fuel delivered
  • tip modifications

  • reduced fuel
  • affect aerodynamic
  • npv calculations
  • annotated brief
  • committee identifies

  • flight profile
  • comparable commercial
  • improving maintenance
  • past studies
  • appropriate strategies


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