SilentHawk is an

all-wheel drive An all-wheel drive vehicle (AWD vehicle) is one with a powertrain capable of providing power to all its wheels, whether full-time or on-demand. The most common forms of all-wheel drive are: ;1x1 : All unicycles Reflecting one axle with one ...

, hybrid-electric

military A military, also known collectively as armed forces, is a heavily armed, highly organized force primarily intended for warfare. It is typically authorized and maintained by a sovereign state, with its members identifiable by their distin ...

bike A bicycle, also called a pedal cycle, bike or cycle, is a human-powered or motor-powered assisted, pedal-driven, single-track vehicle, having two wheels attached to a frame, one behind the other. A is called a cyclist, or bicyclist. ...

designed for the

United States Armed Forces The United States Armed Forces are the military forces of the United States. The armed forces consists of six service branches: the Army, Marine Corps, Navy, Air Force, Space Force, and Coast Guard. The president of the United States is ...

. The bike, currently in its prototype stage, is being developed by

Fairfax Fairfax may refer to: Places United States * Fairfax, California * Fairfax Avenue, a major thoroughfare in Los Angeles, California * Fairfax District, Los Angeles, California, centered on Fairfax Avenue * Fairfax, Georgia * Fairfax, Indiana * Fa ...

Virginia Virginia, officially the Commonwealth of Virginia, is a state in the Mid-Atlantic and Southeastern regions of the United States, between the East Coast of the United States, Atlantic Coast and the Appalachian Mountains. The geography an ...

-based contractor Logos Technologies with the aid of a

Small Business Innovation Research The Small Business Innovation Research (or SBIR) program is a U.S. government funding program, coordinated by the Small Business Administration, intended to help certain small businesses conduct research and development (R&D). Funding takes the f ...

(SBIR) award from the

Defense Advanced Research Projects Agency The Defense Advanced Research Projects Agency (DARPA) is a research and development agency of the United States Department of Defense responsible for the development of emerging technologies for use by the military. Originally known as the Adv ...

(DARPA). According to Logos Technologies, the objective of the SBIR is to deliver a low-acoustic, highly maneuverable vehicle that can carry

American American(s) may refer to: * American, something of, from, or related to the United States of America, commonly known as the " United States" or "America" ** Americans, citizens and nationals of the United States of America ** American ancestry, ...

Special Operations Special operations (S.O.) are military activities conducted, according to NATO, by "specially designated, organized, selected, trained, and equipped forces using unconventional techniques and modes of employment". Special operations may include ...

personnel Employment is a relationship between two parties regulating the provision of paid labour services. Usually based on a contract, one party, the employer, which might be a corporation, a not-for-profit organization, a co-operative, or any ot ...

and their equipment behind enemy lines, over difficult terrain, without being detected.Gould, Joe.
DARPA Pursues Hybrid-Electric Stealth Cycle
" Defense News. 16 March 2015. Retrieved 13 August 2017.

Design and development

The SilentHawk design incorporates an

all-electric An electric vehicle (EV) is a vehicle that uses one or more electric motors for propulsion. It can be powered by a collector system, with electricity from extravehicular sources, or it can be powered autonomously by a battery (sometimes cha ...

RedShift MX dirt bike, produced by

Alta Motors Alta Motors was an American manufacturer of off-road and dual-sport electric motorcycles based in Brisbane, California. History Derek Dorresteyn, whose family has a long presence on the San Francisco motorcycle scene, started working on a bespo ...

Brisbane, California Brisbane (pron. , unlike Brisbane, Queensland, Australia) is a small city located in California in the northern part of San Mateo County, California, San Mateo County on the lower slopes of San Bruno Mountain. It is located on the southern bor ...

, and a multi-fuel genset originally developed by Logos Technologies for a separate unmanned parafoil project. By combining the Logos Technologies genset with the existing 5.8

kWh A kilowatt-hour ( unit symbol: kW⋅h or kW h; commonly written as kWh) is a unit of energy: one kilowatt of power for one hour. In terms of SI derived units with special names, it equals 3.6 megajoules (MJ). Kilowatt-hours are a common bi ...

Alta Motors lithium-ion battery pack, designers contend that they can extend the total range of the bike and also allow it to recharge on the go. The Alta Motors electric motorcycle of the core of the design weighs almost 270 pounds (122.47 kg). Added to that are the SilentHawk features, including a multi-fuel hybrid system, an advanced control system, and auxiliary charging systems. In addition, SilentHawk has an on-demand front-wheel drive hub motor, for improved handling on loose terrain and steep inclines. All this brings the weight of the SilentHawk prototype to 350 pounds (158.76 kg).Atherton, Kelsey D.
Special Forces are Getting a Stealth Motorcycle That's Silent and Deadly
" Popular Science. 26 May 2017. Retrieved 13 August 2017. DARPA first awarded Logos Technologies a Phase 1 SIBR award in February 2014 to the assess the feasibility of developing a hybrid-electric bike. Following that study, the agency awarded a Phase 2 award in December 2014, which led to the development of the current prototype in October 2016.

Features and capabilities

SilentHawk has both a silent electric and hybrid range extension mode. When running in its "silent" electric mode, SilentHawk operates at 55

decibels The decibel (symbol: dB) is a relative unit of measurement equal to one tenth of a bel (B). It expresses the ratio of two values of a power or root-power quantity on a logarithmic scale. Two signals whose levels differ by one decibel have a pow ...

—slightly quieter than the average conversation, which can reach 60 decibels. In its hybrid range extension mode, the bike reaches 75 decibels, or the noise level of a

vacuum cleaner A vacuum cleaner, also known simply as a vacuum or a hoover, is a device that causes suction in order to remove dirt from floors, upholstery, draperies, and other surfaces. It is generally electrically driven. The dirt is collected by either a ...

. SilentHawk can use its genset to recharge the Alta battery pack and any plugged-in electronic devices a rider might be carrying with him. SilentHawk's genset was also designed to burn whatever fuels might be found in the field, including

propane Propane () is a three-carbon alkane with the molecular formula . It is a gas at standard temperature and pressure, but compressible to a transportable liquid. A by-product of natural gas processing and petroleum refining, it is commonly used as ...

gasoline Gasoline (; ) or petrol (; ) (see ) is a transparent, petroleum-derived flammable liquid that is used primarily as a fuel in most spark-ignited internal combustion engines (also known as petrol engines). It consists mostly of organic ...

diesel Diesel may refer to: * Diesel engine, an internal combustion engine where ignition is caused by compression * Diesel fuel, a liquid fuel used in diesel engines * Diesel locomotive, a railway locomotive in which the prime mover is a diesel engine ...

JP5 Jet fuel or aviation turbine fuel (ATF, also abbreviated avtur) is a type of aviation fuel designed for use in aircraft powered by gas-turbine engines. It is colorless to straw-colored in appearance. The most commonly used fuels for commercial av ...

and

JP8 JP-8, or JP8 (for "Jet Propellant 8") is a jet fuel, specified and used widely by the US military. It is specified by MIL-DTL-83133 and British Defence Standard 91-87, and similar to commercial aviation's Jet A-1, but with the addition of corrosio ...

jet

propellants A propellant (or propellent) is a mass that is expelled or expanded in such a way as to create a thrust or other motive force in accordance with Newton's third law of motion, and "propel" a vehicle, projectile, or fluid payload. In vehicles, the e ...

. It has up to 170 miles (273.59 km) total range (including 2 hours in quiet mode), but varies based on speed and terrain. Its top speed can reach up to 80 mph (128.748 km/h). The hard case

saddlebags Saddlebags are bags that are attached to saddles. Horse riding In horse riding, saddlebags sit in various positions, on the back, side, or front of the saddle. Most attach to the saddle by straps and ties. They can be made from various material ...

at the rear of the bike can carry 75 pounds (34 kg) of gear, and mounting points allow for the attaching of additional bags and gear.

Further development

As part of a second Phase 2 SIBR, Logos Technologies is scheduled to produce two SilentHawk bikes for DARPA: an electric one with all-wheel drive and a reduced weight hybrid-electric system with a modular architecture. Company officials say that their plan to lessen the weight of the latter bike involves switching from a liquid-cooled engine to an air-cooled engine and removing SilentHawk's radiators.

Other electric and hybrid-electric military bikes

In addition to SilentHawk, DARPA is sponsoring work on another hybrid-electric bike. That one is called Nightmare, and it is being developed by LSA Autonomy, in Westminster, Md. At 400 pounds, Nightmare weighs more than SilentHawk, but it also generates greater horsepower. In 2013, U.S. Special Operation Forces also conducted testing of the MMX, an all-electric bike developed by Zero Motorcycles for the military. However, the problem with the MMX was that its battery needed to be recharged every 2 hours, and carrying a backup battery would come at the expense of other types of gear carried by the military rider.Commandos' New Stealth Bike Has Drone Origins
" War is Boring. 1 May 2014. Retrieved 13 August 2017.

References

{{reflist All-wheel-drive vehicles Military vehicles of the United States