A cross parachute, looking like a round parachute with slices cut out of the corners, is actually substantially easier and cheaper to make than the round parachute. This is because in its uninflated geometry, the cross parachute is simply a block cross of sectioned material, threaded with support lines. The round parachute is constructed out of more complicated wedge-shaped sections.
The cross parachute examined in this project was a small model constructed and tested by the Parks College Wind Tunnel Center, from which several pictures of results are available. Also available are pictures of the fully inflated geometry of the cross parachute from both the wind tunnel tests and the simulations. The dimensions of the parachute in its flat, uninflated configuration are given below:
|Flat Cross Parachute Dimensions|
The wind tunnel itself is very narrow relative to the dimensions of the parachute; this resulted in severe blockage effects between the parachute and the tunnel walls. These effects were obvious in the simulations, especially when the results using the normal domain were compared with the results using a wider domain.
The dimensions of the wind tunnel are given below. Note that for the simulations, the tunnel length was double the length of the actual wind tunnel test section. Since the outlet flow was free in both cases, this change negligibly effects the simulation results, while allowing more complete visualization of the wake flow of the parachute.
|Wind Tunnel Test Section Dimensions|