The Aerodynamics of Gliding Parachutes

Lingard, J. Stephen

doi:10.2514/6.1986-2427

Cited by 18 publications

(18 citation statements)

References 1 publication

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“…The evolution of C L , is matched by a linear increase in drag to yield the AG100 L/D variation with brake settings shown in Figure 7. This curve very closely follows the shape reported by Lingard 13 for measured values of C L and C D for a ram air wing with AR = 2.0 at 0%, 50%, and 100% flaps. However, the AG100 L/D data is shifted down by .94 and possibly reflects the contribution to the AG100 system in payload drag.…”

Section: A Glide Polar B L/d Figure 6 Ag100 Flight Test Curvessupporting

confidence: 76%

Accuglide: Precision Airdrop Guidance and Control via Glide Slope Control

Bergeron

Fejzic

Tavan

2011

21st AIAA Aerodynamic Decelerator Systems Technology Conference and Seminar

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The Natick Soldier Research, Development, and Engineering Center has been leading an effort to develop precision guided airdrop systems with a CEP under 25-meters. This paper describes the initial work completed using new guidance and control software based on systems and methods similar to those employed by precision accuracy parachutists who routinely land on a 2 cm target. A key component of the Guidance, Navigation, and Control (GNC) methodology is the ability to accurately command toggle inputs to control system glide slope. The AccuGlide 100 system consists of an Airborne Guidance Unit (AGU) built by STARA Technologies, a 100 ft 2 ram-air canopy made by Strong Enterprises, and flight software developed by Draper Laboratory. Nomenclature AR = canopy aspect ratio C L = coefficient of lift, = maximum lift coeff with flaps extended C D = coefficient of drag h = altitude above desired impact point L/D = system lift to drag ratio M r = mass ratio, b = canopy span c = canopy chord x = North coordinate of position with respect to the desired impact point y = East coordinate of position with respect to the desired impact point v air = Estimated airspeed v x = North coordinate of position with respect to the desired impact point = freestream velocity α = Angle of attack ρ air = mass density of air φ = Incidence angle

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Section: A Glide Polar B L/d Figure 6 Ag100 Flight Test Curvessupporting

confidence: 76%

Accuglide: Precision Airdrop Guidance and Control via Glide Slope Control

Bergeron

Fejzic

Tavan

2011

21st AIAA Aerodynamic Decelerator Systems Technology Conference and Seminar

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“…Considering the basic aerodynamics of an airfoil [21] as a very simple model, we claim validity of the following two conditions.…”

Section: Appendix a Derivation Of System Dynamicsmentioning

confidence: 98%

“…It is worth mentioning that we deal with a constrained system that shows a completely different dynamics compared to free-flying parafoils [21]. The basic system is sketched in Fig.…”

Section: Basic System and Coordinatesmentioning

confidence: 99%

Control of Towing Kites for Seagoing Vessels

Erhard¹,

Strauch²

2013

IEEE Trans. Contr. Syst. Technol.

106

122

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In this paper we present the basic features of the flight control of the SkySails towing kite system. After introduction of coordinate definitions and basic system dynamics we introduce a novel model used for controller design and justify its main dynamics with results from system identification based on numerous sea trials. We then present the controller design which we successfully use for operational flights for several years. Finally we explain the generation of dynamical flight patterns.Comment: 12 pages, 18 figures; submitted to IEEE Trans. on Control Systems Technology; revision: Fig. 15 corrected, minor text change

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“…Both laminar (Re=10 4 ) and turbulent (Re=10 6 ) flows are computed. More on the aerodynamics of parafoils can be found in the article by Lingard [3].The aerodynamic design of parachutes is largely an empirical process and the database has mostly been generated via wind tunnel and drop tests. The Baldwin-Lomax model is employed for turbulence closure.…”

mentioning

confidence: 99%

“…More on the aerodynamics of parafoils can be found in the article by Lingard [3]. It involves three-dimensional unsteady turbulent flows past rapidly deforming boundaries.…”

mentioning

confidence: 99%

Computation of two-dimensional flows past ram-air parachutes

Mittal

Saxena

Singh

2001

Int. J. Numer. Meth. Fluids

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Computational results for flow past a two-dimensional model of a ram-air parachute with leading edge cut are presented. Both laminar (Re = 104) and turbulent (Re = 106) flows are computed. A well-proven stabilized finite element method (FEM), which has been applied to various flow problems earlier, is utilized to solve the incompressible Navier-Stokes equations in the primitive variables formulation. The Baldwin-Lomax model is employed for turbulence closure. Turbulent flow computations past a Clarck-Y airfoil without a leading edge cut, for IX = 7.5°, result in an attached flow. The leading edge cut causes the flow to become unsteady and leads to a significant loss in lift and an increase in drag. The flow inside the parafoil cell remains almost stagnant, resulting in a high value of pressure, which is responsible for giving the parafoil its shape. The value of the lift-to-drag ratio obtained with the present computations is in good agreement with those reported in the literature. The effect of the size and location of the leading edge cut is studied. It is found that the flow on the upper surface of the parafoil is fairly insensitive to the configuration of the cut. However, the flow quality on the lower surface improves as the leading edge cut becomes smaller. The lift-to-drag ratio for various configurations of the leading edge cut varies between 3.4 and 5.8. It is observed that even though the time histories of the aerodynamic coefficients from the laminar and turbulent flow computations are quite different, their time-averaged values are quite similar.

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The Aerodynamics of Gliding Parachutes

Cited by 18 publications

References 1 publication

Accuglide: Precision Airdrop Guidance and Control via Glide Slope Control

Accuglide: Precision Airdrop Guidance and Control via Glide Slope Control

Control of Towing Kites for Seagoing Vessels

Computation of two-dimensional flows past ram-air parachutes

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