Inflation and Steady-Descent Characteristics of Truncated Cone Decelerators
Jean Potvin
Saint Louis University
St. Louis, MO 63103, USA
Gary E. Peek
Industrologic Inc.
St. Charles, MO 63301, USA
Presented at the 18th AIAA Aerodynamic Decelerator Systems Conference
and Seminar, Munich, Germany, May 23-26, 2005, AIAA paper 2005-1620
Abstract
We report on the results of a "first look" study of the inflation and
descent characteristics of a new type of parachute - the truncated cone
decelerator (or "TCD"). Featuring a deep conical inflated shape truncated
at the apex, the TCD is being envisaged for use in wind-sensing applications
where GPS-instrumented payloads are to be drifting freely with the wind,
in a stable manner and without gliding. The combination of a low axial
drag area with a high transverse drag area should rank the TCD as one of
the best performers for this type of applications. The paper first presents
the design characteristics of the two 2.3 height-to-base -ratio cones that
were used in this study, namely a three foot-long model and a 16ft-long
model. Next comes the discussion of the experimental data on fall rates,
which yielded drag coefficient values approximating coefficient of drag
approximating 0.25. Data was also obtained with the sub-scale model being
truncated at the vent, at lengths ranging from 0% to 20% of the original
cone height. The paper ends with a discussion of the inflation properties,
which yielded low peak drag forces and non-dimensional filling time values
approximating non-dimensional filling times approximating 13 to 20.
