Perseus (Concept: US Department of Defence)

A lot more detail on the US Army’s plans to test an unmanned hybrid airship for persistent surveillance has emerged in an updated solicitation for the Long Endurance Multi-INT Vehicle (LEMV) demonstration – which is expected to lead to a deployment in Afghanistan. A hybrid airship combines buoyant, aerodynamic and propulsive lift to make it easier to launch and recover than a true lighter-than-air aircraft.

LEMV  has replaced the Persius (Persistent Elevated Reconnaissance Surveillance Intelligence Unmanned System), which was planned as a FY2009 joint capability technology demonstration. Persius was to be awarded to Lockheed Martin Skunk Works, to build a version of its P-791 proof-of-concept hybrid airship, which flew back in January 2006.

The Persius and LEMV specs look almost identical. Army Strategic Command is looking for a demonstrator that can carry a payload of at least 2,500lb to 20,000ft for three weeks. At 20,000ft, the payload line-of-sight would be 173 miles.

The hybrid airship is to be untethered and unmanned, but optionally manned for self-deployment, with the ability to fly a 2,500-mile roundtrip mission. The payload gondola and airship structure is to be capable of carrying a heaver, 5,000lb payload to lower, 10,000ft altitude.

Once on station, the Army wants the autonomous LEMV to station-keep for three weeks, staying within a 3.5km-radius circle 50% of the time, 75km 75% of the time and 150km 95% of the time. A 20kt average cruise speed and 80kt dash are required.

That’s for the demonstrator. The solicitation also requests a growth plan to a higher-performance airship capable of carrying a 7,000lb, 73kW payload to 10,000-20,000ft for at least a month, cruising at 30kt and station-keeping to within 2km 50% of the time and 50km 95% of the time, controlled via satcom from the US.

For the demonstrator, the solicitation spells out three test flights: an initial low-altitude flight and recovery, possibly from the contractor’s facility; an operational-altitude flight with station-keeping for “days” over a military range; and a third flight of 21 days in an “operational environment”, scheduled for the third quarter of FY2011.

A “rapid deflation device” is required to terminate the flight if control is lost, to prevent the aircraft breaching airspace restrictions, or to prevent the sensitive payload falling into the wrong hands.