The LEMV (now HAV 304) made its one and only flight in the US on 12 August 2012 (Hybrid Air Vehicles).

UK airship company Hybrid Air Vehicles are reconfiguring a former US military airship for civil use and have ambitious plans for additional and larger designs. BILL READ reports from Cardington. 

What is 91m long, 34m wide, 26m high and flies? Answer — the Airlander 10 airship.

In recent years there have been many plans to revive the airship as a viable form of air transport but few projects have progressed beyond concept art and small-scale demonstrators. One of the exceptions has been UK airship company Hybrid Air Vehicles (HAV) which now has a genuine full-size airship, the Airlander 10, which it showed off to the press at the end of February. The Airlander 10 has a colourful history, having been originally built in the US for the US Army for use as a surveillance platform over Afghanistan under the name of LEMV (see below). Due to cutbacks in the US military defence budget, the project was subsequently cancelled in 2013 and HAV was able to buy back the airframe, engines and other parts and ship them back to the UK.

The ex-military airship, based on HAV’s HAV 304 platform, is currently being reassembled at the UK’s historic airship base at Cardington in Bedfordshire. HAV gave details of its ambitious plans for the airship’s second life as an experimental demonstrator to pave the way for similar and even larger designs.

Fortunes of war

 

The US Army was interested in a persistent surveillance airship for Afghanistan. (Hybrid Air Vehicles) 

The Airlander 304 airship now at Cardington was originally designed for operation in Afghanistan with the US Army. Known as the Long Endurance Multi-Intelligence Vehicle (LEMV), the airship was intended to provide intelligence, surveillance and reconnaissance (ISR) support for the US Army. The original plan for the LEMV was to provide the US Army with a ‘game-changing’ increase in surveillance operations payload, duration and operating cost reduction. According to a 2011 report published by the Congressional Budget Office, the LEMV would provide a payload-duration 80 times greater that the US Army’s Grey Eagle UAVs at a 500-nautical mile combat radius.

The project began in June 2010 with a contract from the US Army Space and Missile Defense Command/Army Forces Strategic Command. HAV provided the base platform based on its HAV304 hybrid airship design together with fuel modules, engines and hard structures while Northrop Grumman was responsible for system integration, flight and ground control systems. A number of other US companies were also contracted to build and develop particular parts of the LEMV, including fabric made by Warwick Mills in New Hampshire and envelope construction by ILC Dover in Delaware.
The agreement, which originally included options for two additional airships, required the LEMV to be designed, developed and tested within 18 months, prior to its deployment to Afghanistan.

However, the project ran into delays and it was not until 7 August 2012 that it made a 90-minute test flight at Lakehurst, New Jersey — a flight that proved to be its first and last. More problems followed when, in October 2012, a report from the Government Accountability Office claimed that LEMV was 12,000lb overweight, which would cut the airship’s loitering time from 21 days down to only four or five. In February 2013, the US Army announced that the LEMV project had been cancelled, after a total of $297m had been spent on developing the project. The Army said the project had been terminated due to a combination of technical and performance challenges, as well as reductions in the 2014/15 defence budget. The US Air Force had also been developing its own Blue Devil 2 surveillance airship for Afghanistan but this project was cancelled in June 2012.

In September 2013, the LEMV (minus its military equipment) was sold to HAV by the Defense Contract Management Agency (DCMA) for $301,000, less than 1% of its original development cost. The DCMA had hoped to sell the LEMV for $44m but the HAV bid was the only one received.

The LEMV was intended to operate mostly as an unmanned surveillance platform for up for 21 days at heights of up to 20,000ft. The airship was also fitted with a cockpit to allow it to be piloted through civil airspace. If necessary, it could also be used to carry heavy loads to remote locations.

The LEMV was designed to carry up to 1,134kg of payload, either in a payload compartment or suspended on hard points from a ‘universal load beam’. These payloads were intended to provide ground troops with imagery and other data from a range of sensors, including full motion video, ground-moving target indicator radar, electro-optical/infra-red sensors, communications relay systems, blue force tracking, signal intelligence and electronic countermeasures.

While the US military no longer has any direct involvement with continued development of the LEMV design, HAV will continue to supply the US Army with data from the HAV 304 flight tests.

 

Coming home


The HAV 304 hull and mission module arriving at Cardington in December 2013. (Hybrid Air Vehicles)

Once HAV had completed the sale of the former LEMV, the company had only four weeks to ship the components from New Jersey to the UK using a roll-on/roll-off freighter. “The cost of disassembly and shipping was more than we paid for the airship,” stated a HAV spokesman. “We used the biggest box that would go on the UK roads, wheeled it underneath the airship, deflated the envelope and rolled it up. The mission module, which included the flight deck, went on one truck and the big box contained the hull. We also had to transport the engines, fins and mooring masts and spare engines.” 

Hybrid design


The envelope of the HAV 304 prototype has been test inflated with air inside the Cardington hangar but at the time of writing, was yet to have fins, engines and payload module reattached. (Hybrid Air Vehicles)

The HAV 304 has a volume of around 38,000m3 and is designed to be filled with non-flammable helium. The airship has no internal frame and maintains its shape by the pressure of the gas inside it. The envelope is constructed from 55cm wide laminated strips constructed from a combination of Vectran, Kevlar and Mylar laminated fabric. To maximise strength the strips are welded together in a particular weave pattern similar to the creation of carbon composites. “Modern airship hulls have traditionally been built out of polyester which extends under pressure,” explained a HAV spokesman. “However, we have used material with a very low extension under load. Because the material is tensioned under pressure, it is much stronger when inflated but has to be constructed very accurately to get the right shape.” There are six segments inside the hull, four of which have got air cell ballonets inside them. As the airship ascends, the ballonets are deflated to allow space for the helium to expand without having to vent any of the lifting gas.

The hull is fitted with an internal suspension system designed to support a payload module made up of three sections. The first is a flight deck featuring a two-seat cockpit area, and payload compartment which could be used to accommodation up to 50 passengers and a freight bay. The middle section of the module features the universal load beam from which the military sensors were attached, followed by aft fuel tanks.

The HAV 304 is powered by four 350hp direct injection, turbocharged diesel engines, two mounted forward on the hull and two on the stern. All four are configured in ducts with blown vanes to allow vectored thrust in different directions to control take-off, landing and ground-handling operations. Once the airship is flying, the bow engines can be turned off.

Retractable pneumatic tubes fitted to the underside of the two outer hulls enable the airship to act like a ‘hovercraft’, so that it can land and manoeuvre on flat ground and water surfaces. The system can also be put into reverse, enabling the airship to ‘suck down’ to the ground, enhancing its stability while being loaded or unloaded.

Much of the design features of the HAV hybrid airship were created by the late Roger Munk who first showed the practicality of the design in 2000 using the small scale electrically powered remote controlled Skykitten demonstrator. The shape of the airship is an essential part of the hybrid design, as it acts as a flying wing, generating additional lift as the airship travels forward. This aerodynamic shape can provide up to 40% of lift. “If the airship is light enough, it can take-off vertically just using vector thrust,” explains a HAV spokesman. “If it’s more fully loaded, it will need a headwind of around 20-25kt to take-off vertically — or it may need a bit of space to take-off.”

Brave new world

The two-seat cockpit at the front of the payload module. The original military version of the LEMV was designed for remote UAV operations with pilots only being needed when traversing civil airspace. The revamped Airlander 10 will be flown with a pilot.

One of HAV’s major shareholders is aviation enthusiast and entrepreneur Bruce Dickinson, also well known in non-aerospace circles as the lead singer of rock band Iron Maiden, who outlined the new technology used in Airlander: “Barnes Wallis’ R100 airship of the 1920s was a great design but was limited by the technologies of the day,” he explained. “The construction materials were inadequate, the engines were heavy and inefficient, flight controls were cumbersome, radar didn’t exist and navigation and weather forecasting were still at an early stage of development. In later life, Barnes Wallis wrote a note for Roger Munk, saying: ‘Solve these problems and the airship will become an efficient and viable mode of transport.’ The issues to be tackled were stability and flight control, structures, increased payload, more powerful engines, improved capabilities in poor weather and forecasting and easier ground-handling. Now we have the technology to revisit this fundamentally sound design to make it efficient and make it work.”

I’m a mover

HAV has many ideas in mind for different missions in which its airship design could be used, both for civil and military applications. HAV CEO Steve McGlennan explained how the airships were being considered for ‘remote mining’ missions in Canada and West Africa in which they could be used to monitor rare minerals which cannot currently be got out of the ground because of a lack of permits or transport infrastructure. Other applications could include oil spill monitoring, geographic surveys, border patrols, search and rescue, surveillance, humanitarian relief and acting as a communications relay hub.

There has also been interest from the British military for possible ISR missions, as well as an option for the Royal Navy’s Crows Nest airborne surveillance and control aircraft replacement programme. Another suggested application is that the airships could be used to transport F-35 engines onto Britain’s new aircraft carriers without the need for docking. “It helps to have UK and US military interested when talking to other military customers,” says McGlennan, adding that the company was also in talks with militaries in the Middle East and Asia.

Ambitious plans

 

Has aerospace technology finally caught up with the promise of lighter-than-air flight? (Hybrid Air Vehicles) 

With the components for the HAV 304 now back in the UK, HAV’s first aim is to put the airship back together again and test its flying characteristics. Currently the aircraft only has US military flight certification but HAV aims to achieve civil certification with a Type B permit from the UK Civil Aviation Authority (CAA) in the next few weeks. The intention is to operate the ex-military airship as an experimental prototype from which lessons could be learnt for future designs. The ex-LEMV is 12,000lb heavier than it should be — which is one of the reasons the project was cancelled — but HAV is confident that this problem can be resolved in a second vehicle.

One proposal is to use the prototype Airlander 10 to tour Canada and the US in mid-2015 to show its potential for heavy-lift missions in remote areas. The tour would finish in Rio de Janiero in 2016 where the airship could be used for promotional purposes at the Olympic Games.

“Once we’re flown it, then we can train some more pilots,” explains Bruce Dickinson. “Then we want to build another one with a similar chassis but with passenger-carrying capability which can also do traditional things that these vehicles have done.”

Following the construction of a second Airlander 10, HAV’s next plan is to begin work on the Airlander 50, a longer and larger version with a potential payload of 60t for heavy lift operations. The Airlander 50 will be able to carry up to six 20-foot containers in its payload module, subject to a maximum weight of 50t. A 20t lift built-in crane is also included as part of the basic specification. It could also be used as a manned surveillance vehicle, carrying a crew of up to 14 people for a period of up to five days. Work on this airship is planned to begin in 2016 with first flights in 2018.

The potential of HAV’s airship business has been recognised by the UK Government which has offered financial support in the form of a £2·5m grant from the Technology Strategy Board. The grant will be used to model the aerodynamic characteristics of the airship using wind tunnels and fluid dynamic simulations, together with research and development work on large carbon composite structures, hull pressure software control systems improved manufacturing and assembly techniques.

“I think this project has a tremendous future,” states Dickinson, who has invested £0·25m into the project. “Above all, it seizes the imagination. It’s only if you are prejudiced and narrow in your vision that this doesn’t make any sense.”


16 April 2014