The link above, aside from the misspellings, is a very amusing discussion of the politics, aeronautics and logistics of balloon-jamming. But I can't help but doubt the aluminum foil question. Is it true that a tail of foil would give the same radar reflection as a 747? I'll have to ask someone..... [via Sideshow]
UPDATE: A radar expert of my acquaintance [THANKS!] says that a foil strip (particularly one with creases that produce corner echoes) about three square feet in area could well produce a radar reflection equal in strength to that of a commercial airliner, and that the short and fast movements of flapping foil might even produce doppler radar echoes. He also points out that enough flapping foil would serve as a very effective jammer, hiding actual targets.... which is why our missile defense systems are going to have problems. For more information on radar cross-sections, go here.