.... that's a predator drone. A WW2-era Spitfire would have no trouble bringing it down. So if the Iranians fired on that drone and MISSED it's because they were deliberately trying to miss.
U.S. to deliver 8 advanced F-16s to Egypt on July 30-31, U.S. embassy in Cairo says (Reuters)
from the article: Pentagon: Iranian warplanes fired on U.S. drone over Persian Gulf