If I understand your issue, in a loop that executes i times, you are collecting a 2D array consisting of N rows and 15 columns. What you want out of the loop is a 2D array with N rows and 15*i columns. Yes?
If so all you have to do is transpose the matrix you're collecting before appending it to all the data you have collected already. Once all the acquisitions are complete, transpose the resulting array again and you'r done.
See attached, example...
Mike...
PS: If I have the rows and columns backwards, the same technique will still work, but don't do the transposing...
