App for stress-testing wifi

I need to do a stress test of a new wireless network (business) and specifically the AP mesh ability to handle a number of wireless devices pulling some load, and report on that load. No need to go into the gory details.

What I'd like to do is something like this:
- connect 10-20 iPads running iOS 5 to the network
- start some simple app on each that starts transferring a large file from some SMB share visible on the network to the iPad. Big stuff... 10, 15GB files.
- monitor how the network copes

Any suggestions on a simple (ideally free) app can simply copy data over wifi to the local iPad/iPhone as quickly as possible? No need to actually be able to use the data.