Airlander 10 on the ground prior to its first flight. (HAV)
UK airship developer Hybrid Air Vehicles (HAV) experienced a setback when its prototype Airlander 10 airship was damaged after colliding with the ground after its second test flight. Despite this setback, HAV is working hard to repair the airship and resume its test schedule. BILL READ FRAeS reports.
On 17 August Hybrid Air Vehicles’ Airlander 10 hybrid airship ‘Martha Gwyn’ made its first flight in the UK from Cardington Airfield in Bedfordshire. Chief Test Pilot David Burns, accompanied by Test Pilot Simon Davies, ascended to a height of 500ft and flew the airship around a six-mile area around Cardington at a maximum speed of 35 knots. The test objectives for the first flight were to complete the safe launch, flight and landing of the Airlander 1, together with some technical tests on its hull pressure. It was a privilege to fly the Airlander for the first time and it flew wonderfully,” Burns said. “I’m really excited about getting it airborne. It flew like a dream.”
Unfortunately, the second test flight on 24 August proved to be less dreamlike. Airlander 10 flew for 100 minutes in which it conducted turns at increasing speed, as well as climbing and descending to up to 3,000 feet. However, at the conclusion of the flight, Airlander experienced what HAV described as a ‘hard landing’ in which the airship collided with the ground in a nose-down position causing damage to the control cabin. Both pilots were uninjured and the Airlander was returned to the hangar.
According to media reports, HAV sent a report to the UK Air Accident Investigations Board (AAIB) saying that the Airlander had made a successful first landing but the airship took off again while an ‘issue with the mooring mast’ was sorted out. During the second take-off, a 150ft nose mooring line became free and trailed behind the airship. Because of the trailing cable, the Airlander had to make a higher than desired approach to avoid the cable touching the ground - not entirely successfully, as the line did touch some power lines, although this did not contribute to the accident. A video of the second landing shows the Airlander descending very slowly to the ground before landing nose down and then returning to a horizontal position.
Installing the engines onto the Airlander 10. (HAV)
HAV has been quick to assure the media that the Airlander will be repaired and will resume flying. On 31 August the company issued a statement which stated that: “The Company is now undertaking a thorough investigatory process to ensure that all relevant factors which contributed to the heavy landing are identified and that steps are taken to remedy them or to ensure that the risks associated, are properly and safely mitigated before the aircraft returns to flight. This process will involve a report to and discussions with the relevant aerospace industry regulators and our insurer. Through the investigatory process we will arrive at a definitive understanding of the root causes of the event and the necessary steps and timescale to safely return to flight.”
HAV’s Head of Partnerships and Communications, Chris Daniels gave more details: “In terms of the AAIB, they publish on their website any incident or accident they intend to investigate,” he explained. "EASA will also write a report in due course which will be available to industry provided there is a clear need to know for wider learnings.”
Time for repairs
Repairs to the control cabin of the Airlander 10 (seen here before the accident) will require specialist tools. (HAV)
Chris Daniels admitted that the incident has had a knock-on effect on the flight test schedule. “The incident will affect the schedule, as we would have been flying now,” he admits. “However, we were due to be back in the hangar between Phases 1 and 2 (Air Worthiness Release 1 and 2, technically) for some planned upgrades before the more extensive flying we do in the second phase. We’re going to get on with the upgrades while in the hangar now so, in the overall scheme of things, it shouldn’t delay us too much.”
It had been hoped that repairs to the hull and forward part of the cockpit would only take a few days but a recent BBC report claims that there may be a longer delay in repairing the airship, as HAV needs to replace some specialist tools which were not acquired from the airship’s previous operators, the US Army. Together with the time needed to investigate the incident, it may now be three to four months before test flying can be resumed. “We have to do at least 100 hours of flying during the flight test programme and it is likely to be about 200 hours in total,” said Daniels. “Phase 1 is expected to be around six flights and around 20 hours of flying, flying up to 4,000ft and up to 40kt. This is to test basic climbs, descents and turns and some helium pressure tests. We did run through a number of these tests during the second flight and the data gleaned thus far suggests we should be confident we’ll pass through this phase in the planned manner. Phase 2 is around 80 hours and around 20 flights and will involve night flying and longer duration flights - although this is an estimate and could change depending on how the programme goes. Phase 3 thoroughly tests the aircraft and involves testing on two engines rather than four and de-icing etc. These phases are agreed with EASA and we will move to the next phases only after EASA has signed off that we have achieved the objectives in that phase.”
The hybrid Airlander airship design gains lift party from helium and partly from forward motion. (HAV)
Measuring 92m (302ft) in length the Airlander 10 has an envelope constructed of Vectran, Kevlar and Mylar laminated fabric filled with 38,000m3 of helium. The 43·5m-wide envelope has no internal frame and maintains its shape by the pressure of the gas within it. 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 aerofoil shape of the envelope acts as a ‘flying wing’ which can increase lift by up 40% when the airship is in motion. The Airlander 10 is powered by four V8 325hp turbo-diesel ducted propeller engines, two mounted forward on the hull and two on the stern, that can fly at airship at speeds of up to 92mph or be rotated to provide thrust and control for vertical take-offs or landing.
The hull is fitted with an internal suspension system designed to support a payload module comprising a two-seat cockpit, payload compartment and aft fuel tanks. In theory the Airlander 10 will be able carry payloads of up to 10 tonnes (similar to that carried by a Boeing CH-47 Chinook helicopter or an Airbus C295 transport aircraft). The Airlander 10 is also fitted with inflatable amphibious 'skids' enabling it to land on for a wide variety of surfaces. When on the ground it will be secured to a short mast.
Since its return from the US at the end of 2013, where it made one flight in 2012 in its previous incarnation as the now-cancelled US Army Long Endurance, Multi Intelligence Vehicle (LEMV), the Airlander has received a number of modifications. “We’ve made probably around 500 changes,” explained Stephen McGlennan, CEO of Airlander in an interview with AEROSPACE prior to the first flight. “The airship is substantially improved from the version that flew at Lakehurst and is now the Airlander and not the LEMV. The tailfins are 8ft bigger than they were at Lakehurst while we’ve added leading edge route extensions (LERX). We’ve also done a lot of work on the pressure management system.”
Airlander 10 could be grounded for up to three months. (HAV)
While the delays resulting from the hard landing have been a setback for HAV, the project is still alive and well. It must be remembered that the Airlander 10 is the first of its kind and accidents and delays are nothing new in the development of new aircraft types. In recent years, the Airbus A380, Boeing 787 and Bombardier CSeries have all had delays in certification while the A400M, Bell 525 and AW609 have had fatal crashes. It is a tribute to the safety of the Airlander design that it was able to impact the ground without injury or significant damage.
The Airlander 10 is a testbed prototype for the larger-size airships - in particular the 50t payload Airlander 50. Measuring 119m x 60m x 35m, this airship would be lifted by 103,000m³ of helium and could carry up to six 20-foot containers in its payload module, together with a 20t lift built-in crane. The Airlander 50 would also feature a hovercraft skirt instead of landing skids which would enable the airship to ‘suck’ down to the ground and simplify landings.
Proof that there is widespread support from both the public and government for the success of the Airlander project is shown by the £2m raised from crowdsourced funding, a £3.4m grant from the UK Government and an additional €2.5m from the EU Horizon 2020 research and innovation programme. HAV has also raised funds through ‘high net worth individuals’ and institutional investors, among whom are Peter Hambro from the Hambro banking dynasty and Bruce Dickinson from heavy metal band Iron Maiden.
Concept art of a future Airlander 50 being used for construction work. (HAV)
HAV is actively marketing the airship as a potential platform for a variety of different applications, both civil and military. Among the civil applications are resupply and logistics for mining or logging industries in remote areas, ‘remote mining’ missions, oil spill monitoring, geographic surveys, border patrols, search and rescue, surveillance, humanitarian relief, communications relay hub, aerial filming, advertising, cargo carrying and tourist passenger flights. The Airlander is also reported to be attracting interest from countries considering using it for its original purpose as a military surveillance platform. “We’re hoping to get the MoD and UK government interested in doing a trial,” said Stephen McGlennan. “This would be an important signal to overseas customers and would benefit UK plc, as 80% of our supply chain comes from the UK.”