Maneuvers during Automatic Formation Flight of Transport Aircraft for Fuel Savings

Kaden, André; Luckner, Robert

doi:10.2514/6.2020-1255

Cited by 1 publication

(6 citation statements)

References 13 publications

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“…The position at 1 km is farther downstream than 40 spans, which is a typical distance in formation flight simulations in Ref. [15].…”

Section: Comparison Of Induced Wind Fieldsmentioning

confidence: 85%

“…The contour plots on the left of Figs. 15 and 16 show that the local differences between VLM and LLM in the y a -z a plane increase with growing distance behind the leader aircraft, in other words for a higher vortex age. The deviations also become more pronounced for finer discretisations, for example D1 in Fig.…”

Section: Comparison Of Induced Wind Fieldsmentioning

confidence: 98%

“…The comparison is carried out at two positions, x a = 10 b and x a = 1 km behind the aircraft. The first position reflects the minimal distance between aircraft in the recent formation flight simulations at TU Berlin [15]. The second distance marks the end of the computed wind field.…”

Section: Comparison Of Induced Wind Fieldsmentioning

confidence: 99%

“…If the formation is manoeuvring, e.g. changing altitude or course, a pragmatic solution to stay with the "box" technique by adapting the box location and orientation in space was proposed by Kaden [15]. A superior approach would be to use methods, like LLM or VLM that can online address the impact of the lift changes of the vortex-generating aircraft and the impact on the wing.…”

Section: Introductionmentioning

confidence: 99%

“…He compared it to the simple SHVM, see Refs. [5,15]. A set of parameters for the LLM was optimised to match the vortex-induced velocities in the far field, where the roll-up is complete, with SHVM.…”

Section: Introductionmentioning

confidence: 99%

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Simplified vortex methods to model wake vortex roll-up in real-time simulations for fuel-saving formation flight

Spark

Luckner

2022

CEAS Aeronaut J

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One possibility for reducing fuel consumption is to fly in the upwind field of the wake vortex generated by an aircraft that is flying ahead. Migratory birds use this principle. Manually flying an aircraft at the point of optimal fuel reduction is not suited for routine flight operations as the pilot workload is excessively high. Hence, an autopilot function has to carry out this task. For designing the autopilot, a flight mechanical simulation with a wake vortex velocity model is required that has the ability to calculate the vortex-induced velocity fields. This paper contributes to the choice of a real-time simulation method for modelling vortex-induced velocities that the wake vortex of a leading aircraft generates and that the trailing aircraft shall use during fuel-saving formation flight.Two different wake vortex velocity models are introduced and compared during steady, horizontal flight. One model is based on the Lifting Line Method (LLM) and the other on the unsteady Vortex Lattice Method (VLM). Both models are able to calculate the wake vortex roll-up phase for arbitrary lift distributions, whereas the commonly used Single Horseshoe Vortex Model (SHVM) ignores the near-field roll up. The differences in the induced upwind distribution and vortex filament position are analysed for coarse spatial and temporal discretisation that the real-time constraint requires. Despite the more stringent simplifications of LLM, both methods yield similar filament positions and similar velocity fields for the same discretisation of the lifting surfaces. Finally, the influence of the discretisation parameters is discussed and parameter values are recommended for using VLM and LLM in real-time flight simulations.

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“…The position at 1 km is farther downstream than 40 spans, which is a typical distance in formation flight simulations in Ref. [15].…”

Section: Comparison Of Induced Wind Fieldsmentioning

confidence: 85%

Section: Comparison Of Induced Wind Fieldsmentioning

confidence: 98%

Section: Comparison Of Induced Wind Fieldsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%