The Aerodynamic Drag of Parafoils

The parafoil is an aerodynamic decelerator that uses the concept of parachute and airfoil aerodynamics. The device has been used as a parachute for high-precision delivering of payload (military and civilian), to recover sounding rockets, for various tethered applications (to carry instrumentation for weather survey, air pollution measurements, radar tracking systems), and as recreational parachuting since the 1970s, as discussed by Nicolaides and Knapp & Barton . All these systems take advantage of the low landing speed and manoeuvrability of the parafoil. The invention is rather old, and it was used as far back as the second World War for stabilisation of supersonic vehicles by H.G. Heinrich, as reported by Meyer . The essential concept was that in addition to suitable aerodynamic resistance (as the parachute), the parafoil had to provide lift, stability and control, so that it could be used for high precision landing. The technical literature in the field has addressed aerodynamics, performances, and longitudinal stability, from flight testing, wind tunnel measurements and theoretical models. Relevant publications in the field include the work of Lingard , who showed ∗Graduate Student, AIAA Student Member †Lecturer, AIAA senior member. Faculty of Engineering and Physical Sciences, Dept. of Mechanical, Aerospace, Civil Engineering. Corresponding author. E-mail: [email protected]