Hybrid Air Vehicles Airlander 10

HAV 304 and the LEMV requirement During the 1990s, the UK based company Hybrid Air Vehicles (HAV) formed a partnership with US aerospace and defence company Northrop Grumman to promote the type in defence markets, particularly in the US. Following the successful demonstration of the HAV-3 small-scale demonstrator, and with Northrop Grumman as the prime bidder, the hybrid airship concept was accepted for the US Long Endurance Multi-intelligence Vehicle (LEMV) project, in preference to the Lockheed Martin P-791 that had also been submitted. The LEMV programme was intended to demonstrate a medium-altitude long-endurance unmanned aerial vehicle capable of providing Intelligence, surveillance, target acquisition, and reconnaissance (ISTAR) support for ground troops. Besides HAV, UK and US subcontractors included Warwick Mills (fabric engineering and development), ILC Dover (specialised engineering development and manufacturing services), Textron subsidiary AAI Corporation (US Army OneSystem UAV/surveillance aircraft control & information distribution station), Stafford Aero Technologies (flight control systems) and SAIC (full-motion video processing). Northrop Grumman were responsible for the integration of the various electro-optical/infrared, signals intelligence, radar and communications relay payloads onto the airship. With an overall length of , the airship was longer than any contemporary rivals. Operationally, the LEMV was intended to be typically flown autonomously or as a remotely operated aircraft; for being transported to theatres of operation or within normal civil airspace, the airship can also be flown by onboard operators. The LEMV was intended to be capable of a wide variety of roles, including enhanced ISR (Intelligence, surveillance and reconnaissance) capabilities, beyond-line-of-sight communications and signals intelligence collection. There it was reassembled, refurbished and modified for a more general role; accordingly, the aircraft was no longer an example of the HAV 304 design, having been rebuilt into the Airlander 10 prototype instead. Under HAV's ownership, it gained its nickname of "The Flying Bum" (or in American English, "The Flying Buttocks"). The Airlander 10 is designed primarily for civilian use. However it can, like the HAV 304, be fitted for a wide variety of defence roles. ==Design==

Overview , January 2016 The HAV 304 / Airlander 10 is a hybrid airship, achieving lift, and thereby flight, via both aerostatic and aerodynamic forces. Unlike most airship designs, it does not have a circular cross-section, having adopted an elliptical shape with a contoured and flattened hull. This shaping is deliberate so that it acts as a lifting body, contributing aerodynamic lift while the airship is in forward motion; generating up to half of the airship's lift in a similar manner to that of a conventional fixed-wing aeroplane. According to HAV, the design would allow operators to choose among trade-offs between endurance and cargo capacity, carrying up to a maximum of of cargo. The threat posed by windy conditions is in part due to its vast surface area in comparison to most aircraft; in particular, ground operations are more difficult in such conditions, but not thought to reach the extent of becoming impossible. According to HAV chief test pilot David Burns, the danger from missiles was relatively low as they can pass through the airship without forcing it down. The skin is reportedly capable of handling small arms fire and other causes of tears due to a level of built-in redundancy and the relatively-low pressure difference between the inside and outside of the hull. Propulsion The Airlander 10 is powered by a total of four Thielert Centurion V8 diesel engines which drive sets of three-bladed ducted propellers to provide the thrust for both flight and manoeuvring. These engines are positioned in pairs, one set being located towards the rear of the airship, while the other are positioned alongside the sides of the forward fuselage, mounted on stub wings. Each engine is furnished with a generator, which provides electrical power for the airship and its mission systems. The assembly for each of the side-mounted engines can be pivoted 20 degrees in either direction, vectoring the thrust to provide flight control, particularly during landing and taking off; the rear-mounted engines are fixed. By employing thrust vectoring, the engines can direct their thrust downwards to provide additional lift during takeoff. A series of four triangular-shaped variable vanes are positioned behind the engines to provide further control authority by re-directing thrust from the rear engines over the tail fins. While cruising at altitude, propulsion can be switched to a more efficient electric drive fed from the airship's central generator. Due to the hybrid aerostatic/aerodynamic lift approach, fuel can be expended without entering a state of positive buoyancy that would necessitate routine helium venting in order to land, a costly weakness present upon conventional airships. Fuel is primarily contained within the main fuel module housing up to nine tons of fuel; the main tank is supplemented by separate rear and forward tanks, containing up to . To optimise cruising efficiency, the angle of incidence can be adjusted by pumping fuel between the fore and aft tanks. ==Operational history==

The LEMV project and the HAV 304 On 14 June 2010, the agreement for the development of the project was signed between the US Army Space and Missile Defense Command/Army Forces Strategic Command and Northrop Grumman. According to media reports, the first flight of the LEMV was rescheduled in early June 2012; however, unspecified problems again delayed the flight until August 2012. The LEMV required at least of runway (violating the runway-independent requirement), and a tether point with a clear flat area around on which to park, which prevented them from operating at most large bases and all small bases. On 7 August 2012 the LEMV, carrying US Army registration 09-009, conducted its maiden flight over Joint Base McGuire-Dix-Lakehurst, New Jersey. The flight lasted 90 minutes and was performed with a crew on board, being flown by Chief Test Pilot David Burns. Two months after the test flight, the US Army stated that it had concerns about sending the airship abroad; these included safety, transportation to the theatre of operations, and the timeline of deployment. The US Army had planned to demonstrate the first LEMV in Afghanistan 18 months after the signing of the contract; at one point, proposals included plans to construct a further five airships following mission completion. In a statement made by a US Army Space and Missile Defense Command spokesperson, the cancellation was a result of technical and performance challenges that had been encountered, as well as resource constraints that had come into effect. Practical and theoretical knowledge gained was redirected from the LEMV to the JLENS program. Reacquisition and the Airlander 10 prototype The US Army believed that the project's technical data and computer software could be useful for future projects but that selling it would save money. Hybrid Air Vehicles expressed an interest in purchasing the airship, saying they wanted to use it for cold-weather flights and other testing for the development of their proposed "Airlander 50" 50-ton cargo airship. The HAV offer included the basic avionics, mooring masts and spare engines but not the specialist equipment or helium. With this the only offer on the table, in September 2013 the Pentagon sold the LEMV airship back to HAV for $301,000. The deflated airship was returned to the UK, where it underwent reassembly and modification as the Airlander 10 prototype at Cardington Airfield. In April 2014, HAV announced that it was forming an industry team with Selex ES and QinetiQ to develop and demonstrate the sensor capabilities of the Airlander 10, and that a three-month demonstration period for the UK's Ministry of Defence has been planned. One suggested use is as a mother ship for launching multiple UAVs. In April 2014, it was announced that both the European Aviation Safety Agency (EASA) and the UK's Civil Aviation Authority (CAA) had approved the necessary permissions for Airlander 10 to return to flight. At one point, HAV had intended for the airship to have completed reassembly and be ready for test flights by December 2014; however, delays were encountered while additional financing from commercial and government entities was being sought. The project received both UK and EU funding to support the airship's further development, totalling £7 million by March 2016. Crowdfunding from members of the general public also raised £2.1 million. The Airlander 10 is also to serve as a prototype for an even larger version of the airship, referred to as the Airlander 50. On 17 August 2016, the first test flight took place at the aircraft's home base, Cardington Airfield in Bedfordshire, England, and lasted 30 minutes. During the final approach to its mooring mast at the end of its second test flight on 24 August 2016, the airship's mooring rope became entangled in wires and the nose hit the ground, damaging the cockpit. The crew were unharmed. The Airlander 10 was repaired and fitted with inflatable "feet" designed to be deployable in 15 seconds, to protect the cockpit in an emergency landing. It resumed flight testing on 10 May 2017. On 13 June 2017, during its fourth test flight, the Airlander reached an altitude of . On 18 November 2017, the airship broke free from its moorings in a high wind, automatically pulling a safety rip panel so that it deflated and fell to the ground. Two people received minor injuries. In January 2019, it was announced that the aircraft had enabled sufficient data to be gathered to complete its test and certification programme, and would be retired. ==Airlander 10 production version==

Following the prototype tests flights, the Airlander 10 received CAA Production Organisation Approval and EASA Design Organisation Approval. As of January 2020 the company is planning to manufacture a batch of certified, production standard Airlander 10 hybrid airships. Compared to the prototype they are planned to feature reduced aerodynamic drag, improved landing gear and a larger payload cabin. HAV estimate the footprint per passenger on Airlander 10 will be about 9 g/km In February 2022 it was reported that production of the Airlander would be moved to South Yorkshire. In December 2024 the South Yorkshire Mayoral Combined Authority released the first instalment of a £7m loan, prompting the start of initial survey and site work for a manufacturing facility at a 50 hectare site at Carcroft Common, Doncaster. The facility is expected to have a production capacity of 10 units per year. Orders and reservations In June 2022, Spanish airline Air Nostrum announced that they had placed a reservation for ten airships, with delivery scheduled for 2026. The order was doubled to twenty airships in August 2023. ==Technical specifications==