Glide Slope Control Authority for Parafoil Canopies with Variable Incidence Angle

Abstract

The addition of glide slope control to guided airdrop systems has the potential to provide dramatic improvements in landing accuracy. Dynamic rigging incidence control has been demonstrated in flight tests and shown to provide effective glide slope control. The current work presents flight-test results exploring the range of glide slope control that can be achieved with high-performance parafoil canopies of two different aspect ratios. The low- and medium-aspect-ratio canopies have peak glide ratios of 4.4 and 4.9, respectively. By varying the incidence angle in flight, the glide slope can be reduced from these peak values to a glide slope near two for both canopies. Flight tests investigating the relationship between symmetric brake and incidence control demonstrate that symmetric braking produces effective airspeed control with little effect on glide slope, the incidence angle produces significant effects on both glide slope and airspeed, the rapid variation of the incidence angle in flight can lead to significant long period oscillations in both glide slope and airspeed, and the coupled effect of the control mechanisms of incidence angle and symmetric brake can produce dramatic changes in glide slope in any wind condition.