Optimization of constant altitude-constant airspeed flight of turbojet aircraft

Ojha, Shiva Kumar

doi:10.2514/3.46235

Cited by 5 publications

(4 citation statements)

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“…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: 98%

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: 98%

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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“…(14). This function is continuous and defined on the interval 0; ∞, and a brief inspection illustrates that its limits on both ends of the interval are ∞.…”

Section: Optimization Of the Range For Continuous Coveragementioning

confidence: 95%

“…Flying at faster speeds increases fuel consumption and reduces the time on station but may further reduce the transit time; flying at slower speeds would have the opposite effect. To answer new problems of flight optimization, it is typical to derive the Breguet equations, as done, for example, in [11][12][13][14][15][16][17][18]. Using this approach, this study attempts to define the value of the transit C L that provides the best range for continuous coverage (D p ) for both jet and propeller-driven aircraft.…”

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confidence: 99%

Optimization of the Range for Continuous Target Coverage

Vitte

2015

Journal of Aircraft

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The increasing demand for intelligence and surveillance missions has led to the novel use of aircraft (especially unmanned aerial vehicles). Rather than flying long distances or loitering, a fleet of aircraft will maintain a permanent presence at a remote location. Two questions arise: at what distance can this presence be maintained, and at what aerodynamic efficiency shall the aircraft fly during the transits? The Breguet equations for range and endurance provide a preliminary formula for the "range for continuous coverage", in which the aerodynamic coefficients for both transit phases appear. The optimization of these coefficients provides remarkable results: for a given propulsion type and number of aircraft, the lift coefficient for the optimal range for continuous coverage is always a constant multiple of the lift coefficient for the best range (e.g., the best continuous coverage C L for two jet aircraft is 1∕ 3 p of the best range C L ).lift coefficient for the best range for continuous coverage (N aircraft) C L1 = lift coefficient during outbound transit C L2 = lift coefficient during return transit D p = distance between the air base and the mission area e = Oswald span efficiency factor F F = fleet factor g = gravity constant K = 1∕πAe N = number of aircraft in the fleet RIp N = improvement ratio of the range for continuous coverage (N aircraft) S = wing area T Outbound = time required to reach the mission area T Return = time required to return from the mission area T Station = time spent in the mission area T Turnaround = time required for aircraft maintenance between flights (2 h in numeric calculations) TSFC = thrust-specific fuel consumption (jet aircraft) V = aircraft airspeed V End = aircraft airspeed for the best endurance V Rng = aircraft airspeed for the best range V RPi = aircraft airspeed for the best range for continuous coverage (i aircraft) W = Mg, aircraft weight W i = aircraft weight at the beginning of the calculation W f = aircraft weight at the end of the calculation W a = aircraft weight at the end of the outbound transit (aircraft weight at the start of effective mission) W b= aircraft weight at the end of the effective mission (aircraft weight at the start of return transit) η = propeller efficiency ρ = air density

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“…t h -y = lW\IS)pxS*Vi/[c{C DQ p\V* + (1 -n4KW/S)2 }]Differentiate the above equation with respect to Vi, and put dt h -V /dVi = 0. The resulting algebraic relation can be solved, giving the maximum-endurance airspeedVme;A-v of constant h-V flight as [ PSSLCTI J I C D{) JThe lift coefficient C^.me^-v for the maximum endurance of the constant A-V flight is given byCL.t**-v~2(W/S)/( Pl V^.…”

mentioning

confidence: 99%

Optimization of Cruising Flights of Turbojet Aircraft

1995

Flight Performance of Aircraft

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Optimization of constant altitude-constant airspeed flight of turbojet aircraft

Cited by 5 publications

References 1 publication

Reachability of Optimal Cruise Conditions

Reachability of Optimal Cruise Conditions

Optimization of the Range for Continuous Target Coverage

Optimization of Cruising Flights of Turbojet Aircraft

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