Lateral-directional aerodynamics from a large scale parafoil test program

Journal of Guidance, Control, and Dynamics

2003

111

A parafoil controlled by parafoil brake de ection offers a lightweight and space-ef cient control mechanism for autonomous placement of air-dropped payloads to speci ed ground coordinates. The work reported here investigates control issues for a parafoil and payload system with left and right parafoil brakes used as the control mechanism.It is shown that parafoiland payloadsystems can exhibit two basic modes of lateral control, namely,roll and skid steering. These two modes of lateral steering generate lateral response in opposite directions. For example, a roll steer con guration turns left when the right parafoil brake is activated, whereas a skid steer con guration turns right under the same control input. In transition between roll and skid lateral steering, the lateral response is zero, and the system becomes uncontrollable. Angle of incidence, canopy curvature of the parafoil, and magnitude of brake de ections are important design parameters for a controllable parafoil and payload system and greatly effect control response, including whether the basic lateral control mode is roll or skid steering. It is shown how the steering mode switches when fundamental design parameters are altered and as the magnitude of the brake de ection increases. The mode of directional control transitions toward roll steering as the canopy curvature decreases or the angle of incidence becomes more negative. The mode of directional control transitions away from the roll steering mode as the magnitude of the brake de ection increases, and for "large" brake de ections most parafoils will always skid steer. ; C m0 ; C n0 = rolling, pitching, and yawing moment coef cients from no brake de ection C l ± ; C m ± ; C n ± = rolling, pitching, and yawing moment coef cients from a brake de ection C x0 ; C y0 ; C z0 = force coef cients from no brake de ection C x± ; C y± ; C z± = force coef cients from a brake de ection F

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Section: Resultsmentioning

confidence: 99%

Aspects of Control for a Parafoil and Payload System

Journal of Guidance, Control, and Dynamics

2003

111

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“…Forces and moments from apparent mass and inertia are found by relating the fluid's momentum to its kinetic energy in a similar way as Lissman and Brown [16], and are summarized in Eqs. (13)(14)(15)(16)(17). In the apparent mass contributions, it is assumed that the incidence angle is slowly varying so that its derivative is negligible compared with the body angular rates.…”

Section: Parafoil Dynamic Modelmentioning

confidence: 99%

“…A detailed description of the basic mechanical design of the glide slope control mechanism is provided next. Traditional parafoil dynamic models treat the canopy orientation fixed with respect to the payload [11][12][13][14]. These traditional models allow effects such as apparent mass to be easily incorporated.…”

mentioning

confidence: 99%

Use of Variable Incidence Angle for Glide Slope Control of Autonomous Parafoils

Beyer

Journal of Guidance, Control, and Dynamics

2008

“…Traditional parafoil dynamic models treat the canopy orientation fixed with respect to the payload. [11][12][13][14] These traditional models allow effects such as apparent mass to be easily incorporated. A new 6 degree-of-freedom model is created that include changing canopy orientation with respect to the payload and model apparent mass effects in a complete manner.…”

Section: Introductionmentioning

confidence: 99%

Use of Dynamic Incidence Angle for Glide Slope Control of Autonomous Parafoils

Beyer

19th AIAA Aerodynamic Decelerator Systems Technology Conference and Seminar

2007