2 Stealth Helicopter

Combining stealth technology and high-speed data links, the RAH-66 Comanche was supposed to be the armed scout helicopter of the 21st century. But all it did was leave a $6.9 billion-size crater in the U.S. Army's budget. Three things killed the Comanche program: the fall of the Soviet Union, the rise of drones, and the fact that this helo was an engineering mess.

Still, the 2011 Navy SEAL raid on the Osama bin Laden compound spurred excited media talk about stealth helicopters. Had they made a comeback? According to Army Times, the modified MH-60s used in the raid belonged to a short-lived program that ended in 2000. So, no.