The United States Special Operations Command (SOCOM) is in the process of deploying its first Boeing A160T Hummingbird unmanned aerial vehicles (UAVs). The new UAV, developed by Boeing in conjunction with the Defense Advanced Research Projects Agency (DARPA) looks like a traditional helicopter but it goes higher, stays airborne longer, travels farther, and runs more quietly than any helicopter in current use.
The Hummingbird is 35 feet long with a 36 foot rotor diameter. It uses a Pratt & Whitney PW207 turboshaft engine and is designed to fly more than 2,500 nautical miles (around 2,900 regular miles) with a payload of 300 pounds (larger payloads are supported for shorter distances). It can remain airborne for more than 24 hours at a time and can fly up to 160 miles per hour (about 140 knots) at up to 30,000 feet above ground.
Future versions could fly as high as 55,000 feet above the ground and remain airborne for as long as 48 hours. The current ceiling for most conventional helicopters is 20,000 feet and the longest flight endurance of a commercial helicopter is just over 23 hours.
The key to these improvements is Boeing’s new rotor design. Unlike conventional helicopters, the Hummingbird uses a variable speed rotor, allowing operators to slow the rate of rotation to save fuel and operate quietly or speed it up to travel as quickly as possible. The UAV uses a hingeless, rigid carbon fiber construction to allow this variation without inducing vibrational problems that would potentially damage or disable the craft.
USSOCOM took delivery of ten Hummingbirds in November 2008. Initial use of the vehicles includes testing of the Foliage Penetration Reconnaissance Surveillance Tracking and Engagement Radar (FORESTER), a radar designed to detect people and vehicles moving under the cover of foliage. Hummingbirds are also being used as test beds for other DARPA projects including the Autonomous Real-time Ground Ubiquitous Surveillance-Imaging System (ARGUS-IS) system.
Other potential Special Forces uses for the Hummingbirds include precision resupply missions and possibly, emergency medical evacuations (human payloads have not been tested at this point, so there are no immediate or near-term plans to use the vehicles for this purpose). Hummingbirds are not armed, but there is also a possibility that future iterations could include lightweight missiles or other small stealth weapons.
The A160 Hummingbird Unmanned Aerial Vehicle looks like a helicopter but is unlike any other helicopter on the market today. It can reach higher altitudes, hover for longer periods of time, go greater distances and operate much more quietly than current helicopters. And it features a unique optimum speed rotor technology that enables the Hummingbird to adjust the RPM (Revolutions Per Minute) of the rotor blades at different altitudes and cruise speeds.
The A160 joined Boeing’s line of UAVs in May 2004 with the acquisition of Frontier Systems Inc., at Irvine, Calif. The aircraft’s unique characteristics address current and emerging requirements of the U.S. armed forces, the U.S. Department of Homeland Security, and international military and security organizations.
A Boeing Phantom Works team called Advanced Unmanned Systems-Concept Exploration is developing the A160 under a contract with the Defense Advanced Research Projects Agency. The Hummingbird is designed to fly 2,500 nautical miles with endurance in excess of 24 hours and a payload of more than 300 pounds. The autonomously-flown A160 is 35 feet long with a 36-foot rotor diameter. It will fly at an estimated top speed of 140 knots at ceilings up to 30,000 feet, which is about 10,000 feet higher than conventional helicopters can fly today. Future missions for the A160 include reconnaissance, surveillance, target acquisition, communications relay and precision re-supply.
The A160 flew for the first time in January 2002 at a former U.S. Air Force base at Victorville, Calif., where flight-testing of the Hummingbird continues. The A160’s ability to stay aloft a long time at high altitudes is drawing considerable interest from the U.S. Army, the U.S. Navy and U.S. Special Operations Forces.
Potential customers are also paying a lot of attention to the Hummingbird’s unique optimal speed rotor system. During flight, an operator can vary the RPM of the A160’s rotors (speed them up or slow them down) at different altitudes to improve overall efficiency and save fuel. This is quite a departure from conventional rotor systems, which tend to have a fixed rotor RPM regardless of altitude.