The US military is working on plans to demonstrate technology for an ultra-large hybrid airship capable of transporting a complete US Army combat unit from "fort to fight". The heavier-than-air Walrus would be capable of lifting a payload of 500t or more across intercontinental distances and of operating from unimproved landing sites.

The US Defense Advanced Projects Research Agency (DARPA) has issued a request for information on heavylift air vehicles, and plans an industry day in March. The proposed Walrus programme is a follow-on to last year's studies of a family of 30-1,000t-payload hybrid ultra-large aircraft (HULA) by the US Navy.

A hybrid airship combines helium buoyancy with aerodynamic and propulsive lift. DARPA is looking for a vehicle with vertical take-off and landing capability. One or more Walrus air vehicles would be capable of deploying a US Army Future Combat Systems (FCS) unit of action as a complete package of personnel and equipment, ready to fight.

DARPA plans to issue a request for proposals in the third quarter. Multiple Phase 1 contracts will be awarded covering concept definition and risk-reduction technology demonstrations. Plans call for one bidder to be selected in early 2006 to build and flight test a subscale demonstrator for the Walrus.

Likely bidders include Lockheed Martin's Skunk Works, which has been studying ultra-large hybrid airships for several years. The UK's Advanced Technologies Group (ATG) is also interested in the programme. ATG is designing the SkyCat family of hybrid air vehicles. The proposed 1,000t-payload SkyCat 1000 is a 305m (1,000ft)-long, 2 million m3 (71 million ft3)-capacity vehicle capable of flying 7,500km (4,000nm) at a 100kt (185km/h) cruise speed.

The vehicle is powered by six 15,000shp (11,000kW) turboshafts - two pairs of aft engines for propulsion and two forward engines for ground handling and take-off, all four capable of thrust vectoring.

The SkyCat has an air-cushion landing system powered by the same fans used to pressurise the internal ballonets used for buoyancy control. The US Navy's HULA was intended to be capable of operating from water.

Source: Flight International