Optimum cruise lift coefficient in initial design of jet aircraft

Martínez‐Val, Rodrigo; Pérez, Emilio Ortega

doi:10.2514/3.46226

Cited by 28 publications

(15 citation statements)

References 9 publications

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“…In 1992, Martinez-Val re-examined the implications of the Breguet Equation in which the cruise thrust specific fuel consumption was changed from a constant to a function of both speed and altitude. 20 In 1992 and 1993, Ojha and Miller separately published analytical extensions to Breguet assuming parabolic drag. 21,22 Miller noted that his revised equations do not include the possibility that the aircraft is thrust-limited and that thrust limitations can preclude the possibility of reaching the global optimum for range.…”

Section: Iia Steady-state Analytical Approximation Methodsmentioning

confidence: 99%

Reachability of Optimal Cruise Conditions

German

Patterson

Pate

et al. 2012

50th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

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Optimal aircraft cruise performance occurs along particular trajectories traversed through Mach number and altitude space as the mission fuel mass is expended. Ideally, these optimal trajectories depend primarily on the interplay between aerodynamic performance and engine fuel burn rate and on the lapse of these metrics with Mach and altitude. In many situations, however, the ideal operating conditions are constrained by point performance capabilities of the aircraft. For example, stall may limit the efficiency of low speed loiter operations, and maximum speed and altitude capability may reduce the achievable specific range. In this paper, we investigate the implications of thrust limits on aircraft range performance in comparison to unconstrained operations at the cruise conditions corresponding to optimal aerodynamic efficiency. We derive the conditions of optimality for both a twoparameter quadratic drag polar and a drag polar with wave drag, and we demonstrate the concepts by exploring Mach-altitude "sky maps" for three subsonic turbojet aircraft examples. Finally, we explore the implications of changes in the aircraft drag polar, thrust loading, and wing loading on optimal aerodynamic performance.

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Section: Iia Steady-state Analytical Approximation Methodsmentioning

confidence: 99%

Reachability of Optimal Cruise Conditions

German

Patterson

Pate

et al. 2012

50th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

View full text Add to dashboard Cite

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“…The Mach number dependence of the specific fuel consumption [26,27] is explicitly shown in the first denominator. Therefore, the range parameter can be expressed as…”

Section: Fig 4 Process Chain Used For Optimizationmentioning

confidence: 99%

Optimization of planform and cruise conditions of a transport flying wing

Martínez‐Val

Pérez

Puertas

et al. 2010

Proceedings of the Institution of Mechanical Engineers, Part G:

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The flying wing is a promising concept for the mid long-term commercial aviation. After the previously published conceptual design of a 300-seat class flying wing, the present article carries out a parametric analysis to optimize its planform and analyse the suitable cruise conditions to achieve the highest efficiency of such configuration. The figures of merit chosen for the optimization are the direct operating cost and the maximum take-off weight per passenger, for a specified constant range of 10 000 km. The design has to respect five relevant constraints: wingspan (limited to 80 m), cabin width, wing tip chord, number of passengers, and cruise lift coefficient. The optimum aircraft fulfilling all constraints cruises at 45 000-47 000 ft and M = 0.82, has an aspect ratio of 6.3 and taper ratio of 0.10, and carries about 280 passengers in three-class seating. This aircraft is about 20 per cent more efficient than conventional wide bodies of similar size, in terms of trip fuel.

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“…5.1 is assumed, where the first and second terms are the zero-lift and lift-dependent drag respectively (Katz and Plotkin (2001)). (Martinez-Val and Perez (1991) comment that the errors involved in Eq. 5.1 are very small, since drag divergence is not an issue in long-range cruise.…”

Section: Drag Polarmentioning

confidence: 99%

“…where sf c (the specific fuel consumption) is, in general, a function of cruise speed and altitude, and depends on the type of powerplant used (Martinez-Val and Perez (1991)).…”

Section: Cruise Conditionmentioning

confidence: 99%