British aerospace engineer Jason Hill became enthralled with helicopters in his youth while watching the television show, Airwolf, the highly fictionalized account of a Bell 222 converted to a supersonic assault weapon. The experience led to a decades-long dream of producing a stylish, modern light-helicopter design he unveiled in 2020, the five-seat Hill HX50. By last November, Hill Helicopters had attracted hundreds of orders and produced its first carbon-fiber, single-piece fuselage. It plans to begin flight testing by the end of 2023.
The effort, largely funded by Hill’s successful engineering firm Dynamiq, has drawn its share of skeptics, but Hill plods on with near-monthly progress reports he broadcasts live on YouTube. The videos are a quirky combination of a slick infomercial, college engineering lecture, and town hall meeting, in which Hill personally fields live questions from the electronic audience. Other videos posted by the company feature interviews with Hill’s wife, brother, and colleagues, all testifying to Hill’s long-standing and complete commitment to the helicopter. Isabella Hill calls her husband’s drive to build the HX50, “an obsession.”
The carbon-fiber HX50 is more Tesla than Airbus with a splash of Bell 525. The interior, Hill notes, is more spacious than his Range Rover, with a baggage hold easily capable of swallowing three full-sized rollaway bags or multiple sets of golf clubs. Exterior styling cues unmistakably harken back to the 222, amplified with the smooth curves and twists that only molded composite construction can offer. Performance targets include a 140-knot cruise speed, 700-nm maximum range, and 1,760 pounds of useful load.
Hill sees his helicopter as a more attractive alternative to eVTOL aircraft in terms of both practicality and cost. “It’s going to be decades before we have batteries or a means of storing enough electrical energy for a genuinely battery-electric aircraft to be practical. I don’t believe [eVTOLs] offer any material advantage over a well-designed, modern helicopter,” he said in 2021.
A helicopter pilot himself, Hill regularly flies a Robinson R66, and his slavish devotion to creating and manufacturing a near-completely, vertically-integrated aircraft could have been taken straight out of Frank Robinson’s playbook. Hill actually has gone Robinson one better—he plans on building his own 500-shp turboshaft engine.
“We make stuff in-house,” Hill said. “We have absolute, total control of our cost base. What that means for [customers] is not only we deliver you an aircraft at the right price point, it also means that we can control the cost of spares and that the through-life costs of support are properly controlled.” That price point now stands at $708,000 for the base HX50 and slightly less than $1 million for the HC50, a price on par with the Robinson R66.
Like both the R66 and the Bell 505, a variety of options can inflate those numbers quickly. But you would be hard-pressed to find HX50’s option list on any other light helicopter.
Options include in-seat electric heaters and air-conditioned seat ventilation; a refrigerated center console compartment beneath the armrest cushion to chill drinks and snacks; and a power supply for each passenger’s tablet computer with audio streamed directly to passenger headsets. The audio fully integrates with the digital cockpit and onboard audio system.
Each passenger seat can support rear-facing, forward-facing, and booster seats for children. Other options include a pilot-operable folding blade system, a Helimove electric ground handling system, Home Base secure wireless link to power hangar doors, skids or wheeled gear, and an emergency float system. The digital cockpit can include synthetic vision. A two-axis autopilot is standard, a four-axis is optional.
So far the market has responded positively to the plucky Hill’s endeavor. By the end of 2021, Hill had received 342 orders for the kit-built HX50 and yet-uncertified HC50. A year later, in December 2022, that number had more than doubled, closing in on 800 and backed by $36,000 deposits each.
Via the YouTube videos, Hill painstakingly documents progress on the HX50, mindful of the stigma often attached to start-ups and “vaporware.” In late 2022, Hill spent considerable time discussing achievements on the fuselage, engine, and avionics.
“We’ve pulled together a range of technologies from lots of different industries involved in composite production to bring the price point of composite manufacture down to something that we needed,” Hill said. “In order to do that we’ve had to reject the aerospace norms. We’ve vertically integrated not just the carbon-fiber manufacturing but the pattern making, the mold making, and then the part manufacture itself. And with that has come end-to-end control of the quality, the schedule, and the cost—not just the cost of making the finished airframe but also the cost of developing it.”
“We got all of the details right that allowed us to create sharp edges, get the lightning-strike protection in there, and prove that we could make these fuselages in a single piece. We then went on to develop the processes that you need to be able to finish carbon-fiber to the standard that people expect when they’re buying premium products,” Hill said.
To do so, the company adapted techniques from boat building, using a low-cost polystyrene base, a fiberglass cover, and sealing layers, to provide vacuum integrity and facilitate resin infusion. The fuselage itself is more than 33 feet long from tip-to-tail, a size Hill calls “a proper" helicopter.
"It has the proportions really not far off what you’d expect from an [Airbus Helicopters] AStar,” he said. “It’s [the interior] slightly more generous than what I have in my Range Rover.”
Hill will use the first fuselage, built with prototype tooling, to hone human factors calculations. Prior to being stuffed, it weighs around 77 pounds. Hill expects to complete a second full-scale fuselage early this year. The company designed the windows to give both pilot and passengers generous outside viewing, and the rear passenger seats will attach to a bulkhead that allows those passengers to see over the heads of the front-row occupants.
The collective and cyclic controls at first glance appear similar to those in the Bell 525, with one on each side of the pilot position. However, on closer examination, the collective is “nestled into the armrest” to allow the pilot’s elbow to rest while making the needed control inputs.
The digital cockpit display screens are intentionally positioned low so as to not obscure outside vision at an angle Hill describes as “a little below 20 degrees for most people.” A center console between the two front seats provides ample storage for beverage bottles and small snacks.
The fuel bladders hold 175 U.S. gallons and sit behind the rear cabin bulkhead and ahead of another bulkhead for the capacious luggage compartment.
Hill said the company’s GT50 single-stage gas turbine has been progressing “quickly,” aided by the use of 3D printing and driven by a modular design that is “simpler, more efficient, lighter and easier to manufacture” with “an extremely low parts count” and that is “easy to maintain.”
“Our fuel nozzles are actually removable from the outside of the engine, so they can be changed and checked and modified," Hill said. "The fuel manifolds can be accessed from the outside as well." The engine also uses air-blast atomized fuel injectors for better efficiency and fewer emissions. Hill has refined a new annular combustor that will run on both conventional and synthetic biofuels. The company has reached the final stages of completing the aerodynamic optimization and is developing bearings, turbine blisks, gears, transmissions, and fabricated metal components.
Developing the engine, transmission, and components is a particularly complex task. For example, Hill said some of the gears had to be copper-plated prior to heat treating. “When we heat treat gears, we only want to heat treat the teeth. We don’t want the structural parts of the gear and the root material hardened or it would become brittle, have a poor fatigue life, and poor fracture toughness,” Hill said. “You think of all the little things like that we have to do.”
For the cockpit, the company has begun work on flight dynamics and control features including stability augmentation. “Now we’ve got formal aerodynamic design established for the aircraft that allows us to develop the way that the two-axis autopilot will deliver stability augmentation; the altitude, heading, speed, and navigation hold functions; and the haptic feedback to provide envelope protection,” Hill explained. “The four-axis autopilot will give you simultaneous control of altitude, speed, heading, or nav, and it can hover-hold. It gives you essentially cruise control in every aspect of life and then much more extensive envelope protection. All of those things are actively now being developed.”
That includes developing algorithms and software for the digital cockpit and the avionics test bench has been upgraded to include actual flight controls. Glare testing on the display screens and aircraft windows also is underway, as is human factors testing of the cyclic and collective stick, buttons, and switch heads, not just for functionality, but to ensure they convey a tactile “premium feel,” Hill said.
While continuing to focus on development, Hill already is well into planning for production. “The large demand for the aircraft is putting significant pressure on us to make sure our production facility is ready and it’s capable of scaling up to deliver the number of helicopters in the timeframe that we need,” Hill said. “In parallel with all of the activities that are going on from an engineering perspective, we’ve been pushing through all of the planning applications that are required. They’ve all been submitted and are awaiting a decision from the local government [at Creswell, UK]. We’ve got detailed design underway for the manufacturing system. We’ve also now started the procurement exercise for the major chunks of production equipment that we need to deliver all of these processes in-house.”
Hill also recently struck a deal to host the Stoke-on-Trent [Staffordshire, UK] air ambulance at its headquarters heliport. “We’re not paying for the air ambulance itself, but we’ve offered to host the charity at our facility and provide the heliport, fuel, and crew facilities they need. That will dramatically cut the response time for emergency medical services for people in and around Staffordshire and our factory site,” Hill said. “One of my core philosophies is that for a business to be successful, everybody needs to be successful. That means the people that work for us, our customers, and also our neighbors. The Stoke-on-Trent area and the surrounding villages have struggled for many years to gain access to an air ambulance in the UK.”
Community relations aside, the tedious work of aircraft development continues at Hill Helicopters. “I’m under no illusions what we have in front of us,” Hill said, while effusing confidence in the mission. “We can build the aircraft that people want, we can make it look the way you want, we can make it perform the way you want, and we can deliver it at a price point that you can afford. These [new manufacturing] processes fundamentally allow us to make a step change in what you’ve been used to because we can deliver both the performance and safety at that price point. That’s what all of this effort has been about.
“Now it’s just work.”