HAV304's air-inflated hull in the hangar at Cardington

UK-designed airship preparing for flight

A novel airship-like aircraft is set to take to the skies over Britain within the next year. Called HAV304, it will be the first demonstrator for a technology that, according to its backers, can deliver heavy loads to places that have no runways or other infrastructure and are beyond the range of helicopters.

Hybrid Air Vehicles Ltd also plans to capture the public imagination by fitting out the second in a planned series of the craft for passenger flights, with aerial photography, geosurveying and advertising being considered as other potential applications.

The medium-term plan, though, is to build a much larger vehicle, the Airlander 50, which is currently in design. It will carry a load weighing up to 50 tonnes over a range of 3,500km, staying in the air for up to four days at a time.

A heavy-lift vehicle of this kind would open up new possibilities for mining high-value ores in remote areas where access by other transport modes is difficult. It could also be used for supplying oil rigs and for relief efforts. Hovercraft-type pads will allow it to ‘suck itself down’ to any reasonably flat surface for short-term landing in places with no infrastructure or ground crew, before returning to a base with proper mooring and refuelling facilities.

The initial HAV304 was unveiled to the press in February in the historic airship hangar at Cardington, Bedfordshire, where it is being prepared for its flight tests. It has already flown once, in 2012, when it was part of a US military project to build long-endurance surveillance craft in support of operations in Afghanistan. Northrup Grumman led that programme and was developing software and systems that would have let the vehicle stay aloft, unmanned, for up to 21 days, though for the maiden flight it was piloted.

However, the scheme fell victim to US spending cuts, so HAV bought back its vehicle for $300,000 in order to develop it for manned commercial use, having wisely retained all the intellectual property rights. The company is now going through the process of having the craft recategorised from military to civilian, bringing it under the regulatory ambit of the Civil Aviation Authority.

Having arrived at Cardington in January in a series of crates, the HAV304 is now being put back together. The fabric hull, made from a complex sandwich of high-tech materials, has been inflated with air, so it is possible to get an impression of what it will look like in flight, but once structural inspections are complete the air will be replaced with helium, held in seven compartments. The four diesel-engined propulsors will be attached, and the mission and fuel modules suspended below the hull. The mission module contains the flight deck, services area and payload space for cargo or passengers.

According to HAV chief executive Stephen McGlellan, the plan is to fly for the first time by early next year, with a series of demonstration flights in 2015, in parallel with a fundraising programme. He also spoke of an appearance at the Rio Olympics in 2016 with the support of a global sponsor.

“Then on 1 January 2016 we’ll start building the cargo vehicle,” McGlellan continued. “With a three-year build and certification programme the first flight will be in 2018. Meanwhile we’ll be building the second, third and fourth.”

The government-backed Technology Strategy Board has awarded HAV a £2.5m grant as part of a £4m public and private sector project to develop various engineering aspects of hybrid air vehicle technology. These fall into four categories: a detailed model of the aerodynamic characteristics of the aircraft and its engines, using wind tunnels and advanced simulations; a methodology for engineering very large carbon composite structures; software to control and monitor the hull pressure system; and improved manufacturing and assembly techniques to increase hangar capacity for increased production.

Hybrid air vehicles rely on a combination of buoyancy, aerodynamic lift and vectored thrust to work. The vectored (directional) thrust is used mainly during take-off and landing but also allows stable hovering.

The hull is maintained at a pressure slightly higher than the atmosphere, so any leaks will occur slowly. Even under machine-gun fire, it would normally take several hours for damage to become safety-critical.

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