Recap April’s HX50 Monthly Update & Ama

Overall, there has been significant progress since the last update, demonstrating what Hill can achieve through in-house development and production.

24 May 2024

Progress from around the programme

The progress across the entire programme has been remarkable. Since the last update, the pace of activity at Hill Helicopters has been astonishing. There has been a significant emphasis on the commercial side, especially in terms of recruitment. As the development of the HX50 transitions into the production phase, the development team is being significantly expanded to support this work. Additionally, the certification and approvals programme now extends across a wide range of countries, reaching 70 to date.


PC1 is rapidly evolving from an empty, high-ceiling building into a bustling factory, office, and showroom. Extensive work is underway, including the installation of foundational support for a massive gantry mill and crane, routing electrical power, bespoke lighting, and compressed air systems, applying a high-grade epoxy floor coating, and fitting an industrial dust extraction unit. Additionally, a mezzanine floor is being constructed to ensure climate control, which is essential for maintaining the tight tolerances required for aerospace-grade manufacturing.

It’s a lot! But progressing at pace.


Eric has been trialing some improvements to the digital screen displays, incorporating customer feedback. One notable enhancement is the early concept of a nonlinear range for the vertical speed indicator, which he successfully demonstrated on the flight simulator.

At the end of last year, we relocated the airspeed indicator from the bottom to the top of the screen. This change was intended to improve the instrument scan and keep the indicator closer to the pilot's eye line during flight. While this adjustment has been well-received, feedback indicated that the progress bar alone doesn't effectively convey the rate of change in airspeed.

To address this, Eric is developing a concept that uses an elliptical arc for the needle's path, similar to a traditional dial, providing a more intuitive and angular change. This enhancement aims to improve at-a-glance readability.

"This is the benefit of having a simulator. We can quickly iterate on new concepts to test them out," says Eric.

Recently, Eric had the opportunity to test a tablet-based implementation of the Hill digital cockpit hardware. The tablet, featuring our screens, coatings, backlighting, and graphics boards, was placed on his lap during a flight in another aircraft. This experiment allowed us to evaluate the screens' performance under normal flight conditions, focusing on brightness ranges, glare, reflections, font sizes, contrast, and position relative to the pilot's eye point.

The results were positive, with all tests passing. However, we did learn some lessons, particularly regarding day and night themes, and we are currently exploring different variations to improve this aspect.

The objective was to test the feasibility of using a 15.6-inch screen on the pilot's lap, simulating its position in the HX50. The experiment revealed that using a touch screen in a bouncing helicopter works well, especially since the HX50 will have a hand rest to stabilise the pilot's arm.

There are concerns about confined area approaches, particularly with steep angles where the tablet could obstruct the pilot's vision. To address this, we have scheduled tests to explore using a forward- and downward-looking nose camera to provide a live feed on the display.

Another anticipated improvement involves using infrared night vision cameras to provide a pass-through feed onto the display, enhancing situational awareness and pilot safety during night flights.

Additionally, there has been a minor rework of the stick heads on the cyclic collective to better integrate with a modern VFR digital cockpit. One idea is to incorporate an alt key, similar to a keyboard, which would activate an alternative UI palette in certain areas to provide shortcuts. Various options are being examined to optimize the use of this space.


The past month has seen a significant push towards completing various engine components. We are currently manufacturing the test centrifugal impeller for the first in-house GT50 engine. Machining trials have been conducted to optimise tool paths and assess the trade-off between machining time and tooling wear. Cutting of the first four blanks for the initial test impellers is set to begin soon.

The first GT50 high-pressure turbine disc is undergoing final geometric inspections after completing all necessary production processes. It will soon be ready to receive its blades.

We are about to commence the final set of qualification trials for our in-house turbine blade casting process. This required developing extensive controls and non-destructive testing processes, including composition analysis and mechanical testing. We have received the latest batch of crucibles, coated with a special compound, to melt the alloys needed for casting the dumbbell samples and the first batch of GT50 HP turbine blades. The casting process, HIPping, heat treatment, and root grinding processes are all prepared for production.

While much focus has been on the challenging rotating components of the GT50, we have also made progress with the engine casing. Over the past month, we have been designing the runners, feeds, and processing parameters to successfully cast large thin-walled structures like the engine combustion casing in complex materials. Simulations have been used to replicate the range of conditions these structures will face. We are now ready to place the order for the production equipment needed to produce these castings in-house at Production Centre 1.

"Pretty much everything you need to make in a jet engine is difficult to manufacture," says Jason.

Another focus has been the crucial drive shafts for the under-engine drive arrangement of the GT50. We have produced prototypes of both primary drive shafts, which are now undergoing inspection to ensure accurate and reliable production of the thin walls across their full lengths. The third and final shaft, which provides the tail rotor drive from the main rotor, has also been completed.

Combustion testing has reached a new stage. Analysis revealed the need to adjust the combustion flame angle, which was initially too wide and impinged on the combustion liner. The combustion test rig has been upgraded with a larger blower to accommodate a wider range of operating conditions. New instrumentation has been added for more detailed analysis, and improved controls now allow for automatic execution and monitoring of tests.

Key modifications were made to the development swirler and nozzle. The swirler body was broken down into separate components, allowing us to actively change the swirler angle and mass flow during tests. This enables us to optimise the swirler for the full range of operating conditions required for the GT50 engine.

"An interesting point is that while there's a big move in the industry towards rapid prototyping with 3D printing, we can produce updated swirler components faster using conventional methods in-house than by outsourcing," says Jason.

This advantage of in-house manufacturing and vertical integration allowed us to quickly iterate and test the updated nozzle and swirler geometry.

"And what a difference a month makes," adds Jason. Early trials showed a fragile and chaotic flame with a wide cone angle that impinged on the outer liners. Now, we have a strong, stable blue flame.

Another rapidly developing area of the GT50 is the direct drive starter generator, including the MGU unit and its PMU control unit. By last month, all core internal components for the motor, rotor, and stator parts had been produced or were in production.

Over the past month, we finalised all interface components with the engine. All parts have been released to production, and Mark and the team are now busily producing them. We will soon have a full set of five starter generator units ready for testing.

Our test facility has completed its acceptance testing with the manufacturer and will be installed in Production Centre 1, ready for its opening.


Over in DC2, the main focus is on production readiness, both for the release of the flight prototype tooling and fuselages, as well as for building these parts at scale. The primary activities over the last couple of weeks have been refining and improving our mould-making techniques.

We have been conducting extensive vacuum testing on our latest generation tail boom mould and have achieved the very strict vacuum integrity and leak rates necessary for successful infusions. In addition to meeting all the vacuum requirements, we have also achieved the surface finish needed to deliver a relatively pain-free paint process.

We have now ordered the first of our production representative paint booths and all the associated paint equipment, which will allow us to start developing in detail the process for achieving the desired finish quality on the composite panels of your helicopter. The paint booth will be installed directly at PC1.

We have also been preparing material samples for certification material testing and flame testing. We will soon be able to execute the firewall testing to determine the final firewall solution for the flight prototypes.

The team is using the third HX50 scale model to design improved manufacturing processes for incorporating internal details into the monocoque quickly and cost-effectively. Many of our current efforts are focused on accelerating the production process before releasing the final set of tools for the flight aircraft.

Overall, there has been a lot of progress since the last update, demonstrating what Hill can achieve with in-house development and production.

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17 Apr 2024


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