Special operations raids into enemy territory are about to get faster and quieter.
In 2014, DARPA (the Pentagon's research development arm) granted Logos Technologies a small business innovation research grant to develop a military-use hybrid-electric motorcycle with near-silent capability. During this phase, Logos teamed up with Alta Motors to test their RedShift MX dirt bike in multiple terrains and riding conditions to understand troop requirements.
In January 2015, Logos announced that the company was issued a second grant to develop a prototype in partnership with Alta. The Logos-Alta team named their concept dirt bike SilentHawk and plan to have an operational prototype in 18 months. Here's a concept rendering of what it looks like:
According to War Is Boring, the SilentHawk runs on a hybrid-electric drone engine and can use three different fuels – gasoline, diesel, and JP-8, a type of jet fuel. Since the combustion side isn't silent, operators will have to switch to the electric battery when they want to be stealthy.
DARPA has been interested in silenced motorcycles as stealthy, quick, insertion and extraction vehicles for quite some time. According to Defense Industry Daily, Air Force teams have been shoving dirt bikes out of planes since 2010, and the Marine Corps has been training troops on third party vendors since 2012.
Zero Motorcycles toyed with the idea and developed the Zero MMX, but it didn't work out. DARPA pulled their funding because the battery only lasted two hours.
Here's a video of the RedShift in action: