Rotor Technologies: Tackling the Dull, Dirty & Dangerous

Rotor Technologies: Tackling the Dull, Dirty & Dangerous

The start-up aims to unite the benefits of traditional helicopters and unmanned aircraft.

By Justin Bachman

An enormous amount of helicopter work qualifies as perilous. Battling a raging wildfire. Conducting utility inspection work in treacherous terrain. Navigating cornfields dotted with wind turbines. Contending with gusty winds buffeting offshore oil rigs.

In such scenarios, piloting the helicopter remotely could increase safety. It’s not a new idea, of course, with major manufacturers, from Airbus to Bell and Boeing to Sikorsky, all researching the technical promise—and pitfalls—of remotely operated helicopters, many to serve military applications.

On the civilian side of vertical flight, much of the commercial focus has been on electric unmanned aircraft systems (UASs) and manufacturers’ efforts to expand the capabilities of these platforms in areas such as agriculture and surveillance work.

Into this burgeoning field of remotely piloted aircraft comes Rotor Technologies, a small, 40-person New England start-up that’s evolving the well-known Robinson R44 workhorse into its own line of unmanned aerial vehicle (UAV). The company has designated the aircraft the R550 and calls it “the world’s largest civilian drone,” a helicopter that will be flown remotely.

On Aug. 13, Rotor, as the company is known, introduced two R44 derivatives optimized for agricultural spraying work and for construction jobs. Rotor calls the former the Sprayhawk, with a 110-gal. capacity for crop work, and the latter the Airtruck, an R550 that’s designed as a utility vehicle with a payload capacity of 1,000 lb. Rotor says its vehicles will be the “largest and most capable” unmanned civilian vertical takeoff and landing (VTOL) aircraft and slash operating costs as much as half relative to conventional helicopters.

“Rotor is really the intersection of helicopters and the drone world,” says Hector Xu, founder and CEO of Rotor, which is based in Nashua, New Hampshire. “And the hope is to bring the benefits of the two together.”

As technology advances, Rotor and other manufacturers foresee a fertile market for helicopters that will eventually be flown beyond the visual line of sight (BVLOS) of the pilot.

These steps are incremental, from piloting remotely with the aircraft in full view to BVLOS flying to perhaps piloting the aircraft remotely from hundreds or thousands of miles away.

Eventually, as technology matures—and regulators and the public become more comfortable with it—helicopters may operate autonomously, meaning flights will be conducted by software, without human-pilot involvement.

“It’s a spectrum, but I think everybody is thinking about autonomy and how it can bring them benefits, because it’s just a technology that’s really hard to ignore,” says Ben Frank, Rotor’s chief commercial officer. “And it’s really hard to bet against, when you think about it.”

Behind the UAV

Rotor acquires used R44s that have around 2,000 service hours each. The VTOL company then overhauls and retro­fits the helicopters into R550s, transforming them into an Airtruck or a Sprayhawk vehicle. The aircraft is sold with a 2,200-hour service life and comes with warranties and maintenance support provided by Rotor. Robinson holds no equity or other investment in Rotor, which is funded with venture capital, Xu says.

Prices start at $850,000 for the Airtruck and $990,000 for the Sprayhawk, although Rotor describes both of those figures as introductory prices for orders placed before Dec. 15, 2024. The aircraft have a maximum takeoff weight of 2,500 lb. (1,134 kg) each and fly at a top speed of around 104 kt. (120 mph). Rotor formerly referred to the R44-derived platform as the R550X and displayed its prototype UAV at HAI HELI-EXPO 2024 in Anaheim, Calif.

Rotor’s fly-by-wire system functions via computers and multiple communications links and onboard sensors. Neither UAV is rated to carry humans on board; they’re strictly remotely piloted vehicles. (Rotor says future aircraft may carry people, depending on market needs.)

The company plans to boost output to 25 aircraft next year for its first production run, with an initial focus on the US agriculture market, primarily in crop-spraying operations. In the future, Rotor sees commercial end users supporting an output of 50 to 100 aircraft each year.

Customer field testing with two Sprayhawks is set to commence this year, followed by formal deliveries in 2025. “The goal is to begin full-rate commercial operations for spray season next year, which will begin in April or May,” Xu says.

By focusing on a remotely piloted platform, Rotor is avoiding the ambitious pursuit by some electric VTOL start-ups of certification for human-rated autonomous platforms to fly in populated areas and controlled airspace. The FAA is working to certificate several new eVTOLs from companies including Joby and Archer for passenger flights that could begin as soon as 2025.

Rotor’s Sprayhawk UAV is shown equipped with a tank and boom during a test flight to apply chemicals to a field. The aircraft is meant to provide a more cost-effective means of field application work. (Rotor Technologies Photo)

“We’re letting the tiger sleep,” Xu wrote in an “Autonomy Manifesto” the company published on its website in January 2024, noting that the R550 will “operate in the fringes” of the US National Airspace System in mostly unpopulated areas such as crop fields.

Rotor is seeking various exemptions to operate the aircraft under FAA Part 107 rules initially, with plans to fly under the future Part 108 rules the FAA is formulating to govern BVLOS flight.

Given some of the restrictions the agency imposes for Part 107 flying, including an aircraft weight limit of 55 lb. (25 kg), Rotor will “have to navigate their way through the regulatory side of the house in order to put these [aircraft] up,” notes Chris Martino, VAI’s senior director of operations and international affairs. Some of the FAA’s exemptions for Part 107 involve aircraft that operate below 400 ft. (122 m) and under 87 kt. (100 mph), both of which would apply to Sprayhawk agriculture flights.

In this era of growing experimentation with rechargeable UASs, the Sprayhawk comes with two other selling points: the aircraft can be loaded on a trailer for road transport, without the need for rotor stowage or other modifications, and it runs on plain 100LL aviation fuel.

In many remote areas, charging and swapping batteries on a UAV out in the field can prove far more vexing for operators than finding 100LL or simply bringing along extra avgas, Xu says. And larger UAVs often require partial disassembly for trailer transport because of their rotor design, Xu adds.

Rotor is also developing a 24/7 “piloting-as-a-service” product called Cloudpilot. It uses satellite, cellular/LTE, and radio links to enable aircraft to operate autonomously around the world, potentially eliminating the need to deploy a human pilot to each R550 worksite and thereby saving money. The company describes Cloudpilot as a “human-supervised autonomy service”—an alternative to having a human safety pilot on board to take the controls when issues arise.

Rotor executives also envision a secondary but potentially significant line of business: using its proprietary Cloudpilot technology to help equip other VTOL aircraft to operate remotely.

“There’s only so many UAVs we can build. There’s only so many people who want to buy an R44-sized capability-­and-cost aircraft,” Xu says. “And I think this is the way for us to scale our impact more quickly.”

Rotor is also selling an R550 variant for utility and construction work, dubbed the Airtruck, which has a payload capacity of 1,000 lb. (Rotor Technologies Photo)

Why Agriculture?

Across the vertical aviation industry, boosting the safety of “dull, dirty, and dangerous” missions has been a decades-long effort.
“We talked to almost 200 helicopter operators to hear about their problems and to think about where the opportunities were,” says Frank. “We decided that dull, dirty, and dangerous was where we should start. It’s where unmanned aircraft clearly had the best kind of near-term value proposition, where the regulatory case and precedent were the strongest, where the safety case was the easiest.”

Rotor identified agricultural spraying—operations that involve applying pesticides, herbicides, and fungicides to row crops and orchards—as a primary market in the midwestern United States. “Ag is somewhere where there’s a clear use case for this today and people who want it. It’s kind of that simple,” Frank says.
Only “a small fraction” of aerial applicators want BVLOS operating capability, Xu says, which simplifies the regulatory and technical hurdles for remotely piloted helicopters.

“The thing that they really want is high levels of automation,” Xu notes. “They don’t want to be hand-flying this thing around. What they want is to click a button and it’ll spray the field. We’ve seen a shift toward high levels of automation for this specific use case and stripping back some of the more technically challenging things, like very long-range flight.”

In recent years, farmers have flocked to remotely piloted UAVs from companies such as DJI and Yamaha to apply chemicals to their crops. Still, UAVs, which are far smaller than traditional aircraft, remain a tiny part of the overall mix for row-crop spraying and other work in agricultural aviation, says Andrew Moore, CEO of the National Agricultural Aviation Association (NAAA).

For most ag-spraying operations, growers provide size and shape files to load into computer programs or apps that design aerial treatment plans. Once they’re completed, pilots download the programmed plans to USB drives and feed them to the UAV. This process will work just as well with the Sprayhawk, Frank says.

“We’re not trying to reinvent the wheel with everything here,” Frank says. “We’re trying to make use of the existing systems, tools, and processes that people already have in place.”

More than a quarter of all US cropland, or about 127 million acres, is sprayed, according to NAAA data. Helicopters make up about 16% of the domestic fleet of aerial applicators, with fixed-wing aircraft making up the bulk of the field.

“Nothing beats the speed and hopper [payload] capacity of a manned helicopter or fixed-wing aircraft flights,” Moore says.

About 900 agriculture operators are currently registered with the FAA to fly UAVs under Part 137 regulations, with about 1,940 vehicles registered for aerial application. These UAVs are almost exclusively a “complementary addition” to the same operators’ manned-helicopter and fixed-wing aircraft flights, Moore says.

“I do think there’s some competition [with traditional helicopters], but you’re seeing uncrewed aircraft treating areas you typically wouldn’t try to get [a crewed] aircraft into for safety reasons,” Moore continues. “And that’s what some of the hybrid operations are doing.”

One of the operational issues smaller UAVs confront is the sheer size of most midwestern fields that grow corn, soybeans, and other crops. The industry requires multiple manned assets to accomplish the needed spraying, Moore says.

“There’s no way that acreage can be treated by current commercial UAVs,” Moore adds. “It’s manned aircraft because of their speed and capacity. [Because of] the amount of corn in Iowa, Indiana, Illinois, Nebraska, and other corn states, you have [manned] ag aircraft coming in from other states” in high season to meet the demand.

Current UAV operations also require workers in the field to change batteries and refill hoppers, and “labor’s hard to find in agriculture,” Moore says. “A lot of people don’t want to do that work. Sometimes it’s hard work, with hot, humid, long days.”

Another issue benefiting fixed-wing and rotary-wing aircraft in the agricultural-application industry is “a century of testing and calibrating and understanding how manned aircraft work in terms of how to position the boom, how and where it sits in relation to the wings or rotors, how to drop the boom,” Moore says.

“There’s been testing done on spray efficacy, testing done on drift potential, and there are models on how to set up your aircraft to maximize efficacy and mitigate drift,” Moore explains.

“With drones, they’re still working on how to model all that, how to set it up properly, how to maximize efficacy.” He goes on to point out that the Sprayhawk benefits from its R44 platform, which has been modeled and tested. “They know how that’s going to work.”

CEO and cofounder Hector Xu started Rotor after several years conducting post-doctoral research in aerospace engineering. (Rotor Technologies Photo)

Anticipating Market Evolution

The true economics of large, remotely piloted VTOLs will resolve themselves only as the industry scales, VAI’s Martino says, pointing to the many questions the market will address over time.

For example, how will maintenance costs in the future compare between remotely piloted helicopters and manned aircraft? Will the remotely piloted vehicle operate with a single ground pilot, or will it need a team of pilots? Do operator rest and fatigue rules make ground-based helicopter pilots more efficient? Will flying from the ground affect pilots’ wages?

“A lot of folks think UAVs will replace manned helicopters. They’re not going to replace helicopters,” Martino says. “It’s completely foreseeable that for the future of legacy helicopter operations, operators are not only going to have helicopters, they’re also going to have some unmanned systems. It will provide more capability for them to meet their customers’ needs.”

Utility work using UAVs has become common across the United States and the United Kingdom (UK), with companies such as Pacific Gas & Electric, San Diego Gas & Electric, Entergy, and the UK’s National Grid Group all flying UAVs for various inspection missions.

It’s easy to foresee that an operator with 15 to 20 traditional aircraft today may in the future operate with 10 traditional aircraft and 20 UASs, Martino says. “It comes down to the work that can be done by those unmanned systems and how that can help offset the manned side of the house,” he says.

Beyond agricultural applications, Rotor sees plenty of market space for an unmanned helicopter to operate in wildfires as both a surveillance tool and to drop water or fire retardants. A Rotor UAV or its successors could inspect utility lines and wind turbines or ferry parts and other supplies to oil rigs offshore.

As the technology continues to evolve, the future of VTOLs almost inevitably will involve more vehicles piloted remotely—if not by themselves one day.

“I think the key for us is how to save some lives, sell some unmanned helicopters, and make some money, not to be crass about it,” says Xu, a London native who has settled in New Hampshire after years in Boston as an MIT student and post-doctoral researcher studying aerospace engineering and plasma physics. “I’m very grateful we’ve taken this path that is more focused on the near-term market­places, because it allows us to build a lot of maturity.”

Justin Bachman is a professional writer specializing in aviation news and analysis.