The LDSD1 parachute is too large to test in any current wind tunnel, the only test possible on the ground was the rocket sled test.
In this NASA Edge episode (starting at 15:12), Ian Clark talked about modelling the SIAD2, saying it is a rigid body and so scale models can be tested.
Why aren't scale models of the parachute useful for testing?
Did software modelling help at all with the design? At 10:15 of the press conference for LDSD this week, Clark talked about how limited the data for supersonic parachutes was before the first LDSD test, and how much the data from it improved understandings of the dynamics. Are we at all close to being able to create a software simulation for that?
Because really, how do you design a supersonic parachute without such tools?3
1 Low Density Supersonic Decelerator
2 Supersonic Inflatable Aerodynamic Decelerator
3 That question is perhaps not really answerable briefly. But I just had to ask.