In August 2020, Hill Helicopters made their surprise announcement of a new aircraft design with an anticipated first flight in 2022. This would be a tight timeline for any manufacturer, but Hill Helicopters themselves were only formed the month prior, making it all the more ambitious.
Company founder Jason Hill described how the aircraft had been designed for a single mission. “Everything about [the HX-50] is about the use case and the mission of a private owner,” he said. “This is an exquisitely appointed Grand Tourer of the sky.”
The company has released several renders of the aircraft, and describe it as a single-engine light helicopter with a maximum take-off weight (MTOW) of 1,650kg (3,640lb) and a useful load of around 800kg. These figures place it firmly alongside the Bell 505 Jetranger X, however Hill says that the helicopter’s singular mission design sets it apart, saying: “We are not designing an aerial pickup truck.”
Artists impressions of both the aircraft and the interior have been released, showing the cockpit as being fitted with a panoramic all-glass touchscreen panel designed to integrate a tablet computer. Traditional helicopter controls have been modified such that the cyclic can easily be moved out of the way for ease of boarding, and the collective can comfortably be used with the left arm supported by an arm rest. This feature has meant a complete rethink of the control, with it moving fore and aft rather than the traditional up and down motion.
The airframe itself appears to be an all-composite monocoque construction with retractable undercarriage and a three-bladed rotor head which is shown as being completely shrouded. This indicates that drag reduction has been a particular focus and therefore speed is likely to be a priority for the design team.
Hill says the HX-50 will be capable of carrying five 95kg occupants and their baggage with three hours of fuel, up to 10,000′ without performance limitation. The aircraft is expected to have a 5000 hour life on condition, without any calendar-life components. The company says that this will preserve the value of the aircraft, reducing fixed costs and allowing conscientious owners to fly the aircraft as little or as much as they wish.
These are bold claims, particularly given that the Hill Helicopters have also announced that they are developing their own power plant in-house. Their GT-50 gas turbine engine will be in the 500shp class, and the company says that developing the engine alongside the helicopter has allowed it to be optimised for the aircraft. The engine will also feature a FADEC (Full Authority Digital Engine Control) with manual reversion.
The design and timeline for first delivery are incredibly ambitious, and the single-mission focus uncharacteristically uncompromising, especially given that the helicopter industry typically relies on aircraft being capable of performing many different roles in order to be economically viable.
However, Hill has a great deal of aerospace experience built running his own engineering company Dynamiq Engineering, which specialises in Finite Element Analysis, Computational Fluid Dynamics and product development; skills all essential to bringing a new aircraft to fruition, and indicative that the HX-50 is likely to have had a much longer design timeline than the few months that Hill Helicopters has been incorporated.
However, the flight test and production of a clean-sheet design remains a huge undertaking, even for established OEMs (Original Equipment Manufacturers). Not least of this are the costs involved. However, this has not discouraged early orders, with at least three production slots already having been sold. Adding confidence for these early adopters has likely been the fact that Hill Helicopters is entirely owned by its Founder.
While the company has not given specific financial details, the project is thought to have received at least £1.4m of British government funding through Innovate UK and Hill Helicopters say that the UK CAA (Civil Aviation Authority) has been an enabler, rather than a hinderance, in development.
The topic of certification raises obvious questions, but the background of the company suggests that they are not likely to be naive to the difficulties that this process usually presents, particularly to designs that are completely new in both aircraft and engine.
Hill Helicopters haven’t made a public announcement about how they intend to take their design from a computer rendering through to operational service. But given what they have released so far, it is unlikely that their route through certification will be any more traditional.
More information can be found at https://www.hillhelicopters.com.