I would imagine Windy's Russian Sweeper was the biggest in the modern era (and very cool, too), though he didn't win (placed 4th or 5th, I think). Paul's B-17 is more than 900 square inches, but he didn't win with it either. The Spectrum, Impact, TP, Infinity are all around the same size wingspan wise (within an inch or two), though I think the TP is around 660 squares and the Impact is near 700. Hard to tell the smallest, but I think the above is probably right. A Nobler derivative of some type.