Would-be rotorcraft manufacturer Hill Helicopters is hopeful of performing a first ground run of its GT50 turboshaft engine in the autumn, but the maiden sortie of the HX50 light-single it is intended to power will not take place until the second quarter of 2024 at the earliest.
Disclosing its development progress in an online programme update on 16 August, Dr Jason Hill, the company’s founder, chairman, and chief designer, said components for the first test engine were now in production.
Prior to assembly of the powerplant it will conduct separate tests of the starter-generator and annular combustor, the latter on a specially designed test rig.
Dr Hill says the company is targeting a “first run of the combustion system in October”, which will be “rapidly followed by the whole gas generator unit”.
Timelines for the first flight of the HX50 were not disclosed during the event, but Hill Helicopters says it plans on “starting ground running of the first prototypes by Q2 of next year, with flight tests happening shortly after that”.
Hill Helicopters intends to conduct the flight-test campaign with a three-strong fleet from an as-yet undisclosed location. It is not seeking type approval for the HX50, but the helicopter will conform to current certification standards.
Production of the initial customer aircraft is scheduled to begin in early 2025, leading to a first delivery later that year, it says. A fully certified version called the HC50 will arrive by the end of 2026.
Despite the relatively short period allocated for flight testing, Hill Helicopters insists this will not be an issue: “There will be sufficient time to do all the required flight testing on the three prototype aircraft,” it says.
At this point last year, the start-up planned to begin delivering the helicopter in late 2024, following a first flight towards the end of 2023 or early 2024.
In the background, Hill Helicopters has been working to qualify and mature the production processes for the engine and fuselage, which are being manufactured entirely in house.
“We have to make sure we have developed all the manufacturing processes properly and we are not just baking in designs that are hard to make,” he says.
Assessments so far, however, have provided confidence that “we can build this engine to the quality, to the life, and to the price”, Dr Hill adds.
Three prototype drivetrains are also being built, he says, including the first for flight test. In addition, production of fuselages and tail booms for the flying prototypes is under way.
Hill Helicopters intends to showcase a completed HX50 and the GT50 engine at a customer event to be held in the UK in December.
Sales of the HX50 – which due to regulations will only be available to private users – and the HC50 have been brisk: Hill Helicopters has now taken orders for a total of 902 aircraft, split 733 to 169, respectively.
Meanwhile, the company continues to await a decision on its application to build a final assembly line for the helicopters on a site near Cresswell in the English Midlands.
Additional noise assessments have taken place, resulting in changes to the proposed flight corridors and aircraft movements at the site, says Dr Hill.
“We are expecting the noise levels from that work to show that the impact will be below the level for which there is any measurable impact on human health,” he adds.
However, should planning permission not be forthcoming, then the company has contingency plans in place. “There are lots of ways that we can put this [helicopter] into production quickly,” he says.
Development of the prototypes is taking place across several adjacent industrial units in Rugeley, around 15 miles (24km) away from the proposed production plant.
And although the HX50 has yet to fly, Dr Hill is already contemplating a larger twin-engined variant he tentatively calls the HC80. This would have eight seats, be IFR capable and have a maximum take-off weight of 1.375t.
No schedule has been disclosed for development of the HC80.