The Guided Parafoil Airborne Delivery System Program

Wailes, William; Harrington, Nancy Grant

doi:10.2514/6.1995-1538

Cited by 15 publications

(8 citation statements)

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“…Over the years, the computer simulation of the inflation of slider-reefed parafoils has been carried out with a variety of models that include drag evolutions based on time-polynomial drag area laws [1,2], or CFD-based drag area computations using a prescribed wing expansion rate [3,4], or a dynamical description of the slider-descent phase only [5,6]. Although very approximate, these schemes have yielded qualitative and sometimes quantitative agreement with parachute opening data.…”

Section: Introductionmentioning

confidence: 99%

Three-Stage Model for Slider-Reefed Parafoil Inflation

Potvin

Peek²

2007

19th AIAA Aerodynamic Decelerator Systems Technology Conference and Seminar

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This paper discusses the definition and validation of an upgraded model of slider-reefed parafoil inflation. Unlike an early version which focused only on the slider-descent phase, this improved model incorporates the dynamics of the all-important slider-up phase which precedes slider-descent. The model is "dynamical" in that it involves a physical description of the cell inflation process and corresponding parachute drag area expansion. The upgrade is also detailed enough to require over 15 input parameters describing the deployment conditions, canopy dimensions, and most importantly, slider dimensions and drag characteristics. The simulation outputs not only include the evolutions of the drag force and parachute-payload descent rate, but also the actual duration of the slider-up stage. The model can be applied to both sail-slider and pilot chutecontrolled slider configurations, but not to sliders that are physically and temporarily attached to the wing during the early phases of inflation. It will be shown that simulations are the most accurate for canopy-slider designs that have been "tuned" to reduce surging. Nomenclature a(t) = Instant value of the parachute-payload acceleration/deceleration a max = Maximum deceleration sustained during the slider descent phase A c-inlet = Mean center cell opened surface area during the center cell pressurization stage A outboardcell = Mean opened outboard cell surface area during the outboard cell pressurization stage C D (t) = Instant drag coefficient of the parafoil F inlet = Fraction of mean opened center cell inlet, in terms of total center cell inlet area F end = Fraction of final canopy drag area (after slider-descent) to steady state drag area F linedrive = Net slider down-pushing force (minus grommet friction) F max = Maximum drag force sustained during inflation F sliderdrag = Drag force generated by the slider g = Acceleration of gravity constant (t) S(t))Σ slider-extra = Extra slider drag area (generated by PCS pilot chute, slider dome geometry, etc.) Σ slider = Slider drag area (from fabric within grommeted frame) θ(t) = Angle between the side wall of the tip cells and the horizontal <(1-sinΩ-μcosΩ)> = "Slider-push" factor during the slider-descent phase <Δ(t)> = Average value of the dynamical factor of the canopy spreading rate constant <Σ sld > = Average canopy drag area during the slider-descent phase

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Section: Introductionmentioning

confidence: 99%

Three-Stage Model for Slider-Reefed Parafoil Inflation

Potvin

Peek²

2007

19th AIAA Aerodynamic Decelerator Systems Technology Conference and Seminar

View full text Add to dashboard Cite

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“…The GNC system for GPADS 7,8 was developed by the European Space Agency. 22,[29][30][31][32][33] The Parafoil Technology Demonstrator program was set up and conducted under ESA to demonstrate feasibility of guiding a large-scale parafoil autonomously to a predefined point and to perform a flared landing within a specific range.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, ram-air parafoils are nowadays considered a vital element of the unmanned air vehicles (UAVs) capability and of International Space Station (ISS) crew rescue vehicle. [4][5][6][7][8][9][10][11][12] Autonomous parafoil capability implies delivering the system to a desired landing point from an arbitrary release point using onboard computer, sensors and actuators. This requires development of a guidance, navigation and control (GNC) system.…”

Section: Introductionmentioning

confidence: 99%

Development of Control Algorithm for the Autonomous Gliding Delivery System

Kaminer

Yakimenko

2003

17th AIAA Aerodynamic Decelerator Systems Technology Conference and Seminar

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Abstract. The paper considers the development and simulation testing of the control algorithms for an autonomous high-glide aerial delivery system, which consists of 650sq.ft rectangular double-skin parafoil and 500lb payload. The paper applies optimal control analysis to the real-time trajectory generation. Resulting guidance and control system includes tracking this reference trajectory using a nonlinear tracking controller. The paper presents the description of the algorithm along with simulation results and ends with guidelines for the further implementation of the developed software aboard the real system.

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“…This model simulates a ram-air parafoil (wing) that is similar to that flown under the U.S. Army GPADS 27 and NASA X-38 28 programs. For simplicity and reduction of computational time, the parafoil is modeled in half-plane symmetry.…”

Section: B Opening Of a Ram-air Parafoil Systemmentioning

confidence: 99%

Simulation and Modeling of Wind Effects on Airdrop Systems

Accorsi¹,

Leonard²,

Tezduyar³

2001

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Public reporting burden for this collection of information is estimated to average 1 hour per response, including the maintaining the data needed, and completing and reviewing this collection of information. • A rigorous method is needed to model the loss of tension in fabric membrane structures such as parachute canopies. Fabric structures do not support compressive stresses and undergo "wrinkling" at the onset of compression. Since the behavior of a structure will differ dramatically depending on whether there is compression or no-compression, it is necessary to account for wrinkling in parachute systems. SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES)10• Special CSD models are needed to model Pneumatic Muscle Actuators (PMAs) for simulation of NWV candidate systems. PMAs are the primary control device being used in the NWV PAD program. PMAs utilize a braided fiber cylinder that undergoes large relative motions under rapid pressurization. A geometrically nonlinear formulation for PMAs is required.• Stand-alone CSD simulations are needed to verify the structural model and to provide a preliminary modeling capability for candidate NWV systems. Standalone CSD simulations with approximate fluid loads (prescribed pressure and velocity dependent drag) Computational Fluid Dynamics• A robust fluid dynamics model is required to simulate flow fields that involve moving boundaries and interface. For the CFD model, it is necessary to solve the time-dependent, 3D Navier-Stokes equations for incompressible flow. Additionally, the CFD model must account for the moving boundary corresponding to the parachute canopy.• Sophisticated mesh generation algorithms are needed to automatically generate and update the CFD mesh with moving boundaries and interfaces. As the parachute system deforms and travels through the fluid medium, the fluid mesh must conform to the moving boundary.• Computational methods are needed to simulate the effects of adverse wind fields on parachute systems. The CFD model must also include a general method to prescribe wind conditions on the parachute model.• Stand-alone CFD simulations are needed to verify the fluid dynamics model. To verify the CFD model, stand-alone simulations are performed with prescribed structural geometry. Fluid-Structure Interaction• A robust method is required to couple the CSD and CFD to perform FSI simulations. FSI simulations require the interchange of data between the CSD and CFD models. Specifically, the CSD model must pass the structural displacements and velocities to the CFD model and the CFD model must pass the fluid pressures to the CFD model. This data interchange occurs for each time step and an iterative coupling scheme is required to insure convergence of the FSI model. SUMMARY OF RESULTSThe goal of this project has been to develop computational tools for the simulation of candidate airdrop systems for the New World Vistas (NWV) Precision Airdrop (PAD) program. To achieve this goal, the following results were completed:• The CSD, CFD, and FSI models were form...

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The Guided Parafoil Airborne Delivery System Program

Cited by 15 publications

References 0 publications

Three-Stage Model for Slider-Reefed Parafoil Inflation

Three-Stage Model for Slider-Reefed Parafoil Inflation

Development of Control Algorithm for the Autonomous Gliding Delivery System

Simulation and Modeling of Wind Effects on Airdrop Systems

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