Back in 2014, DARPA launched a fantastic stealth bike competition, and two years later the two most important prototypes were presented at the Tampa Convention Center as part of the National Defense Industrial Association’s Special Operations Forces Industry Conference. Dubbed Silent Hawk and Nightmare, both of these bikes received funding from DARPA, and they both flaunt cutting-edge hybrid multi-fuel engines that can run on various fuel types such as Jet A-1, JP-8, propane or gasoline.
The thing is, when these bikes run on conventional fuel, they’re quite loud as they generate about 80 decibels. In quiet mode, however, they get their juice from a lithium-ion electric battery that brings the noise down to about 55 decibels. As far as weight is concerned, the Nightmare tips the scales at around 400 pounds while the Silent Hawk weighs 350 pounds, and in terms of power, the Nightmare is the one that wins the round.