Say this for DARPA, it's not shy about picking ominous names for its projects. Or, in this case, not worried when the partners it works with choose them. Pictured above: the "Nightmare" a "stealth bike" developed by LSA Autonomy for DARPA that has just been moved on to the second stage of development, according to Defense One. DARPA commissioned both it and another bike from Logos Technologies to meet some specific goals: run quietly on electric power, but also run on whatever fuel a soldier in the field.

Alex Dzwill of Logos told Defense One that its bike, the SilentHawk, could run on anything from gasoline to propane to jet fuel: "It will figure it out."

Both are prototypes for now, but Logos has been touting its SilentHawk concepts for a couple years now. It intends to create a bike that can reach 55 mph on "rugged terrain" with a removable combustion engine and that its electric motor — at least in early prototypes — was to be based on something unique. In 2014, Logos told War is Boring, "Our hybrid-electric propulsion system has already been proven on a prior aircraft program."