Operational Analysis for the Formation Flight for Aerodynamic Benefit Program

Flanzer, Tristan C.; Bieniawski, Stefan R.

doi:10.2514/6.2014-1460

Cited by 18 publications

(11 citation statements)

References 13 publications

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“…This collaboration between several research institutions and companies in the US is looking in considerable depth into aerodynamic aspects as well as practical and operational considerations (17) . Work has been carried out in the last three years using heavily instrumented USAF C-17 aircraft flying from 18 to 70 wingspans distance, and the results published so far indicate trailing aircraft drag reductions of up to 25% and fuel burn savings of up to 11% for real mission conditions (18,19) . Alongside the extensive flight testing programme, computational and analytical exercises have been completed, and the agreement between them has been extremely good.…”

Section: Review Of Formation Flightmentioning

confidence: 99%

“…The large number of existing flights would also increase the opportunities for grouping up flights, and it could be argued the challenge would in fact be the daily optimisation of the system, because as discussed in Ref. 19 one seemingly advantageous pairing could leave another aircraft with fewer options and lead to a non-optimal situation. Politics will likely play an important part as well.…”

Section: Review Of Formation Flightmentioning

confidence: 99%

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Formation flight investigation for highly efficient future civil transport aircraft

2016

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Formation flight could greatly assist the air transport industry in tackling the challenges of environmental impact, excessive reliance on fuel and overcapacity. Previous studies have shown drag reductions leading to significant fuel savings for aircraft in formation relative to their solo flight. Safety is guaranteed with the use of extended formation distances, and practical implementation issues could be solved in the near future. Since studies so far have focused on existing aircraft configurations and technology, a case study using a strut-braced wing airliner was carried out to ascertain its applicability to less conventional craft. The present results did not indicate such clear-cut benefits. If formation flight is to be successful and beneficial for the next generations of aircraft, it will be vital to consider its interaction with new technologies developed for highly efficient operation, in particular those aimed at reduction of aircraft drag such as laminar flow, and to do so early in the design of aerospace vehicles and wider systems.

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Section: Review Of Formation Flightmentioning

confidence: 99%

Section: Review Of Formation Flightmentioning

confidence: 99%

Formation flight investigation for highly efficient future civil transport aircraft

2016

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“…The authors are aware of the experimental and mathematical modelling work conducted on the current topic by DARPA, AFRL and Boeing since 2007, and outlined in references [2], [6], [7], [3] and [4]. This previous work was conducted under the NASA Surfing Aircraft Vortices for Energy project.…”

Section: Introductionmentioning

confidence: 99%

Analysis of wake surfing benefits using a fast unsteady vortex lattice method

Fleischmann

Lone

2019

AIAA Scitech 2019 Forum

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The computer simulation framework Flexit is used to analyse the fuel economy benefit of aircraft wake surfing. Wake surfing involves multiple aircraft flying in close formation during cruise conditions to reduce overall induced drag and improve overall fuel efficiency. The aircraft fly in echelon such that the kinetic energy lost in vortices generated by the lead aircraft can be partially recovered by the following aircraft flying in regions of the wake where induced velocities have an upwardly directed vertical component. We build on recent theoretical and flight test work by developing a medium fidelity methodology using Flexit for predicting potential performance benefits of wake surfing. We present results from a specific systematic parametric study that corresponds to a series of recent flight tests with two C-17 transport aircraft to demonstrate the methodology and predict the fuel savings that can be obtained by different arrangements of aircraft in a wake surfing formation. The predictions are compared with the flight test data and the trends observed in our simulations agree with the trends of the full scale tests.

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“…The date of flight test indicated that a 15-20% reduction in drag had been achieved for the trailing F/A-18 aircraft [13][14][15]. In 2008, DARPA and the Air Force Research Laboratories began to fund the Formation Flight for Aerodynamic Benefit program to verify the ability of the C-17s by flying in formation; it was demonstrated that greater than 10% fuel burn savings for the trailing aircraft could be autonomously achieved over long durations [16,17]. Then, the Air Force Research Lab investigated the possibility of using formation flight in coronet missions to save fuel through operational analysis; the results showed that a 14.15% and a 14.53% reduction in thrust were possible for the F-15C and F-15E, respectively [18,19].…”

Section: Introductionmentioning

confidence: 99%

Numerical Aerodynamic Characteristics Analysis of the Close Formation Flight

Dong

Chen

Dong

et al. 2018

Mathematical Problems in Engineering

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The aerodynamic characteristics of the close formation flight are numerically analyzed to facilitate a greater understanding of the vortex effects between UAVs and technically support the application of close formation flight for UAVs. The aerodynamic characteristics of a single UAV are calculated, the results of which are used as the reference to the variation of aerodynamic values in the comparison with close formation flight. The vortex effects of the leading UAV on the aerodynamic characteristics of the trailing UAV in the two UAV close formation flight are analyzed. The position where the trailing UAV obtains the maximum lift-to-drag ratio is defined as the optimal position. Based on the optimal position, three different types of three UAV formations are designed to explore the preliminary application of the aerodynamic benefits in the close formation flight for multiple UAVs. It is observed that the incremental aerodynamic forces and moments of the trailing UAV vary with the lateral and vertical spacing between the two UAVs, and the trailing UAV can obtain significant aerodynamic improvement if positioned at optimal position behind the leading UAV while in close formation flight. It is also proved that the aerodynamic characteristics of the close formation for three UAVs can be improved when the formation is designed based on the optimal position, and this will increase the range and endurance of the UAVs in operational application.

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Operational Analysis for the Formation Flight for Aerodynamic Benefit Program

Cited by 18 publications

References 13 publications

Formation flight investigation for highly efficient future civil transport aircraft

Formation flight investigation for highly efficient future civil transport aircraft

Analysis of wake surfing benefits using a fast unsteady vortex lattice method

Numerical Aerodynamic Characteristics Analysis of the Close Formation Flight

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