16:42 27 July 2016
Words: Robin Evans Photos: Hybrid Air Vehicles
Artist’s impression of Airlander 50 in service
PIL MAY16 FEATURE
If you thought airships had their day back in the early 20th century, think again. The futuristic Airlander is set to revolutionise and exploit hybrid aircraft opportunities and it s British.
To send a link to this page you must be logged in. In a massive hangar in the Bedfordshire countryside, a giant is awakening. The Airlander is claimed to be the world s most innovative, practical and commercially useful hybrid aircraft . It is the creation of Hybrid Air Vehicles (HAV), a British company born of decades of research into lighter-than-air (LTA) technology, in particular by the late airship pioneer Roger Munk. Its unique design was patented in 2001 and realised in a $300 million partnership between HAV and aerospace giant Northrop Grumman. Then branded the Long Endurance Multi-Intelligence Vehicle (LEMV), it was intended for unblinking eye long-range surveillance for the US Army, operating in hostile theatres such as Afghanistan. It flew only once, in New Jersey in 2012, before the United States economy stalled and all rights to the project were bought back by HAV. After budget cuts killed the programme, the LEMV and all test data were impounded in the US under International Traffic in Arms Regulations. Once released, the project team had only a tiny window to devise a way to pack up their vehicle and vacate the premises. The project returned home to Cardington, Bedfordshire in 2014, since when a growing work force ‘now 100-strong ‘has been reassembling and testing this specialised aircraft, mastering the technical challenges required to propel the project to commercial success. The object of these intense labours has been hidden behind some extremely large 470-tonne doors but is about to become very visible, with the first UK test flight due at around the time this edition of Pilot appears.
In the 1970s, Barnes Wallis, chief designer of the R100 airship and a leading exponent of LTA technology identified key issues to resolve to unlock its full potential: improved fabrics, thrust vectoring, better flight controls and composites. Since then, we ve been waiting for technology to catch up ‘the Airlander would have been impossible even a decade ago. The technological problems with airships that have stopped them ruling the skies have been gradually ticked off, says HAV Technical Director Mike Durham. Advances in materials, avionics and aerodynamic design mean that we have overcome the lion s share of these obstacles. The Airlander departs from traditional airship construction in key areas. It is less than half the length of 1930s leviathans like the Hindenburg but, at 92 metres long and 26 metres high, it is the world s largest aircraft, dwarfing the A380. Gone are the heavy, inner framework of girders and flammable hydrogen bags, replaced by a self-supporting envelope filled with helium.
Unique design
One of the rear engines and the port tailplane being lifted into place early in 2016 at Cardlington
The Airlander is uniquely positioned to operate efficiently and sustainably between the helicopter, aeroplane and Unmanned Aerial Vehicle (UAV), hence the term hybrid. So revolutionary is the concept that HAV is in the unusual position of discussing with EASA how to apply regulations set in place for both airships and aeroplanes: the Airlander is not quite either. The design avoids the expense and maintenance intervals of a helicopter as there is no single stress point at the main rotor. The free lift of buoyancy permits a manned endurance of days, plus a much lower carbon footprint and noise signature. With a ten-tonne payload it exceeds the lifting capacity of a traditional UAV or ruggedized aeroplane. It does not require a runway, or even a prepared surface; ice, water and desert are no longer off-limits which opens up more hostile parts of the globe. It is the only type of long-range vehicle suited for door-to-door lifting or monitoring operations with near zero infrastructure. The phrase to describe all these attributes rolled into one hyper efficient platform is game-changing .
Although luxury transport is one proposed use, the Airlander is particularly suited to more rugged environments: for example disaster relief, mining, reconnaissance, surveying minefields and environmental monitoring. Deliveries to communities in the Northwest Territories of Canada or taking heavy infrastructure like wind turbines and generators into remotest Australia or Scandinavia all become possible. It can land directly on-site, not dependent on the nearest large airport. Head of Partnerships, Chris Daniels confirms the potential is huge: We have been approached by someone who wanted to use the vehicle to observe giant squid off the coast of Antarctica. Because the Airlander can take off and land anywhere and stay airborne for days, people will find amazing ways of using it. The Airlander is also scalable. In line for development is a larger, fifty-tonne payload super-lifter that will unlock a key metric in air transportation: cost per tonne kilometre. Analysis has shown that the Airlander 50 could undercut fixed wing, rotary cargo and Ice Road Trucker – style haulage into new frontiers. Imagine a mining company slashing the costs associated with opening a new site in remote territory; infrastructure can be lifted directly in by ISO container and raw materials returned, never needing to build a road. This is both an engineering dream and sustainable enterprise. Independent assessment suggests a $50 billion market over the next two decades and 600-plus opportunities to sell Airlander variants across three areas: passenger, cargo and airborne platform. HAV is considered market leader in this technology by years and aims to be in profit with a proven vehicle inside several years.
One of the rear engines and the port tailplane being lifted into place early in 2016 at Cardlington
Such an unusual prototype prompted equally individual financing ‘over 2 million has been raised via crowd funding, with more from business angels, green technology grants and venture capital. Perhaps the most prominent exponent is one of our own, Iron Maiden s Bruce Dickinson; exactly the sort of enthusiastic character this fledgling project needs. It was Dickinson who introduced me to footage of the maiden test flight at an event in 2013 ‘search for LEMV Lakehurst to see the same.
A special place
Cardington has special significance: it was from these mammoth hangars, now 100 years old, that the first airships emerged pursuing a dream to connect the Empire. Immense in silhouette, with a floor space of five acres each, these Grade II listed green giants were the only obvious evidence of a once mighty industry, both parties having seen better days. Less obvious evidence can be found in Cardington itself. The village sign proudly displays an airship and, more poignantly, in the church is a memorial and the tattered ensign salvaged from the wreckage of the R101 in Beauvais, France in 1930. Once listed on the at-risk historic register, the iconic hangars have been restored recently, a multi-million pound commitment to the rebirth of both the spiritual home and UK production of airships. Even living locally, I was unaware of what was unfolding, until the first signs of restoration became visible when the project returned in 2014. HAV maintains that its presence here is more practical than nostalgic. A venue of sufficient size is needed and Cardington is ideally positioned on the skills corridor between contributing partners: Cranfield University performed the aerodynamic testing and Forward Composites of Huntingdon assists with the structures. Awareness is slowly growing, fuelled by the innovative Airlander Club. Currently over 2,000 members receive news updates and have their names stencilled on the hull. Supporters are welcomed on regular hard hat hangar tours, led by project staff and in this way you too could end up at Airlander HQ.
Assembling the four engines, the distinctive array of thrust-rectoring butterfly vanes clearly visible
Meet Mary
Inside the cavernous Hangar One, there s a quiet, intense atmosphere. Mary , as the team affectionately call her, was reinflated in late 2015. Footage of the initial helium inflation is eerie and impressive: something so vast, floating unsupported in mid-air. Referring to the re-inflation, Mike Durham says, It s very satisfying for the team and me to get another milestone under our belts. We re hugely excited about the forthcoming Airlander first flight this year. Work is currently focussed upon the final stages of the return to flight programme, connecting components to the hull and engine testing, all geared towards flight this spring. With skilled labour and decades of persistence, the UK airship industry, largely dormant for almost half a century, is being slowly rebuilt one significant milestone at a time. Seeing Mary up close, even in the context of these hangars is otherworldly almost alien. Imagine a block of flats lying prone but anchored in place with concrete blocks, just in case.
There are several ant-like sub-assembly teams working in parallel around the hull. Industrial fans cycle on and off, briefly interrupting discussion. This, alongside the articulated trailer of gas cylinders parked outside, is the life-support system until the hull is sealed. With Mary fully inflated but still being worked on, partial buoyancy is carefully controlled with a variable air/helium fill. Internal volume is 38,000 cubic metres, about fifteen Olympic-sized swimming pools.
From ahead, the double hull shape is apparent, the ‘Mission Module’ being attached beneath. The noise docking point, yet to be installed, sits forward of the flight deck
The hull is a triple-ply laminate of heat-welded panels, a few millimetres thick: a strong inner weave of Vectran (a Kevlar derivative) with a tough outer coating of Tedlar. Sandwiched between is an impermeable, helium-retaining Mylar slice. Helium is safe; it is employed in cryogenics (cooling the Large Hadron Collider) and technical diving mixes. It is a tiny molecule, used as a tracer in industrial leak detection, so the hull must be absolutely helium-tight. How do you test a newly-inflated prototype for leaking helium? Head of Production, Stuart Farrell compares it to an enormous bike inner tube… out came the cherry pickers and pressure washers in search of bubbles. In operation, a small top-up is envisaged on an annual basis only. Standard terminology becomes abstract when discussing such an unusual creation. It sits on long, inflatable skids, intended to be sucked in once airborne and blown out again for landing. In profile, it has that bulbous, blimp shape but is much wider. From either end this reveals itself as two large hulls with a smaller lobe between. High above is a curved upper profile, key to the unique aerodynamic design. The hulls taper rearward, accommodating newly-installed carbon-composite tail battens. These will receive the tail cones and rear engines, fibre-optic cables for the control system are coiled ready in place. A forward pair of engines will be mounted upon pylons stitched into the hull fabric, whilst two pairs of 9 x 11metre carbon fibre fins stand upright alongside. The nearby Mission Module houses the flight deck and attaches to a payload beam that runs the length of the central lobe. Any other payload can also be slung here, with the fuel tanks attached at the rear. Mary s official designation is Airlander 10, reflecting the intended payload capacity in tonnes. A variety of Mission Modules can be designed and attached depending upon the intended use, just like Thunderbird Two ‘another giant multi-role support vehicle, if a fictional one. There s a sense of science-fiction rapidly evaporating.
Propulsion comes from four 350hp Thielert turbocharged V8 diesel engines, allowing a planned ceiling of 20,000 feet and a cruise speed of eighty knots. The forward engines vector thrust only up or down, to avoid blowing directly into the side of the hull, while the rear pair have distinctive triangular fins that coordinate vectoring in any plane. In reconnaissance loiter mode the Airlander was designed to operate on one engine, so in an emergency could fly after the loss of three. With a loss of all engines, it would still glide/float under control to land on any surface.
Away from the hive of activity, Chief Test Pilot Dave Burns, at the controls for the maiden LEMV test in 2012, is busy in the new simulator. Understandably focussed on the 200 hour flight test programme, he explains: For the first flight, Airlander 10 will fly up and down the valley between Cardington and the A1, where it is mostly farmers fields. We ll take it to about 3,000 feet, later it will go up to 10,000. People will be able to see it for miles and I expect many will think the aliens are landing! Dave likens the Airlander to a ship in flight: Flying it is more like sailing, in that things happen at a lower speed. You need to be thinking ahead. Any adjustment takes a moment to have an effect. It does however take off more like an aeroplane. The normal method is to perform a rolling takeoff, just like a fixed-wing aircraft. If an engine fails or there is any other significant failure before the V1 & Vr of thirty knots, the takeoff is abandoned. Above thirty knots the takeoff is continued and the climb-out can be safely executed in terms of obstacle clearance and directional control in case of engine failure. Registered G-PHRG, Mary will remain at Cardington as the demonstrator, while the data returned by the test programme will be fed back into
the eventual, type-certified model.
Manourving here at low altitude, test pilot Dave Burns is pitching up while yawing to the right
Although the flight deck itself is still being assembled, the simulator is an instantly recognisable glass cockpit, a side-stick sitting in the right hand with thrust levers in the left. The overhead panel houses an orderly array of square pushbuttons and circuit breakers for fuel pumps, buoyancy control, engines, electrics and fuel. Outboard of the thrust levers lies a fifth lever for engine vane detents, akin to flap positions. A switch slaves external cameras to a monitor, as all engines will be invisible and inaudible to the pilot sitting beneath the hull. Internal ballonets have been used in conventional airships for some time and the Airlander is no different. The hull is compartmentalised with four of these components ‘smaller, air-filled inner balloons that are used to control pressure and, in the case of the Airlander, fore and aft trim. Hull pressure is around 0.2psi, which sounds very low to hold up such a structure, but is all that is required with such a volume of helium. Key to the self-supporting structure is skin tension, a function of pressure and radius. We have little pressure but lots of radius. I can walk along the top of the hull and I sink in just half an inch, so it s a very stiff structure , explains Mike Durham.
Innovation and challenges
Such a revolutionary design has been achieved through horizontal innovation , i.e. borrowing technology from other industries. Communications inspired the digital control network; the interconnection of flight deck, flight controls and engines is via fly-by-light fibre optics rather than electrical fly-bywire. Fibre optics function better over such a large vehicle and are highly resistant to electromagnetic interference. Transducers at the controls emit signals that are digitised, encoded into light pulses and sent to electrical drive units around the fuselage. The hull material is a product of America s Cup sail technology ‘a light but incredibly strong fabric, heat-welded by US firm ILC Dover, known for their NASA spacesuit pedigree.
Eighty per cent of this aircraft is made by British companies and we are trying to stay as British as we can, says Mike Durham. Look at the UK aerospace industry today. Predominantly, we make bits for other people s aircraft. This is a British business that makes complete aircraft. Many challenges have been overcome to repurpose a vehicle originally intended for the military. However, a military pedigree has advantages: the Airlander is inherently damage tolerant, making it a very safe proposition for civilian applications. It is more robust than you might imagine; the compartmentalisation of the hull allows multiple punctures without compromising buoyancy. That low differential pressure avoids explosive damage and even when the hull is holed, the gas will only ooze out, as proven in destructive testing. Helium is an inert element. As Bruce Dickinson observes, People say, God, the Hindenburg! But on this you are flying the world s biggest fire extinguisher. Against the history of the airship, it is perhaps going to be a battle to turn around perception, as Chris Daniels admits, One of the biggest challenges we re going to have is to tell the world just how safe this is.
For an inert element, helium availability is more volatile. This precious resource could be the next crude oil: a high-demand commodity that cannot be manufactured, only extracted from natural wells. Historically controlled by the United States for airships and the space race, new plants in Qatar and Algeria now meet a growing thirst, driven by industrial cryogenics. Prices have stabilised but estimates of peak supply vary greatly.
Despite the physical scale involved, the things that really strike are the intangibles: the quiet intensity, vision and enthusiasm slowly propelling this project towards completion, just like Concorde, hovercraft and the Harrier ‘other incongruous British innovations. In the same vein, it is remarkable what has been achieved over both long and short timescales when you look beyond the history of the word airship . So beware of special VFR traffic south of Bedford from the spring.
Readers can discover more about the Airlander and The Airlander Club at:
www.hybridairvehicles.com[1]
References
^ www.hybridairvehicles.com (www.hybridairvehicles.com)