US to deploy 'optionally manned' hover-dirigible in 2011

The US military will deploy an "optionally manned" 250-foot surveillance airship to Afghanistan by the middle of 2011, according to reports. The dirigible spy-ship will be able to lurk high above Afghan battlefields for up to three weeks at a time, relaying information to ground commanders.

Aviation Week reports that the US Army Space and Missile Defence Command is putting together a group of organisations aimed at building an enlarged version of the well-known prototype P-791 airship test-flown in 2006 (see the vid above). The new, bigger ship will be termed the Long Endurance Multi-intelligence Vehicle (LEMV).

The P-791 and the LEMV which will follow it are termed "hybrid" airship designs as they are not supported entirely by the buoyancy of their lifting gas like a conventional sky-ship. Rather, 80 per cent of their weight is supported by the gas cells and the remainder by aerodynamic lift when the ship is underway.

To move about on the ground, the missing 20 per cent lift is generated by a hovercraft-style aircushion system (the round openings underneath), allowing the craft to be taxied about. The aircushion can also be switched into reverse, allowing the ship to suck itself down firmly in place and potentially avoid the need for mooring masts and/or large ground-handling teams.

In order to lift off before gathering speed, such a ship uses vertical thrust from its swivelling propulsors, in this case driven by powerful turbodiesels. Once in the cruise, these fuel-hungry engines are shut down and the props are driven electrically by a central generator.

The P-791 was actually built with a view to heavy military airlift. The much, much bigger "Walrus" transports intended to develop from the prototype were intended to haul hundreds of tons to a landing far from base deep in rough terrain - perhaps dropping off a large, well-equipped ground combat unit.

via US to deploy 'optionally manned' hover-dirigible in 2011 • The Register.