Reaching for the Sky

On March 9, two U.S. Air Force pilots became the first airmen to fly an electric vertical takeoff and landing (eVTOL) vehicle. The milestone stems from a two-year partnership between BETA Technologies, which developed the aircraft, and Agility Prime, the Air Force’s initiative to partner with the commercial sector to accelerate development of eVTOL aircraft.

Pilots Hank Griffiths and Maj. Jonathan Appleby conducted several flight demonstrations of BETA’s ALIA aircraft at the company’s Plattsburgh, N.Y., testing facility. With a wingspan of 50 feet, the ALIA can fly 250 nautical miles and carry a pilot and three standard pallets or a pilot and five passengers.

Operating under the Air Force’s AFWERX innovation arm, Agility Prime was launched in 2020 and has awarded 22 contracts to 14 eVTOL aircraft developers, as well as more than 250 contracts to small businesses and universities to conduct research and development.

In a YouTube video promoting Agility Prime, Col. Nathan Diller, AFWERX director, said, “If there is an entirely new way of doing mobility in the air, we have to be in the middle of that.”

The Air Force is not the only organization immersed in the expansive advanced air mobility (AAM) market aimed at using transformational designs and technologies to move people and cargo more easily between destinations. An aircraft directory maintained by the Vertical Flight Society cites more than 200 companies working on eVTOL vehicles, from startups to aerospace OEMs like Boeing and the mobility service provider Uber.

There’s energy in the burgeoning market – and growing pains, too, as companies develop vehicles and move toward commercialization.

Stages of Development

“The challenge for the advanced air mobility market is that we’re aiming to eventually reach volumes more familiar to the automotive industry while retaining the extremely high standards required by aerospace regulations,” says Oliver Walker-Jones, head of marketing and communications at Joby Aviation Inc., a developer of eVTOL aircraft.

Transitioning from prototypes to full-scale production presents numerous hurdles for both aerospace leaders, with little expertise in high-volume production, and new players to the market.

“If you look at eVTOL aircraft, they are quite often being designed by people outside the normal aerospace industry,” says Jim Sherman, director of strategic development for the Vertical Flight Society. “They bring a different perspective, but they also don’t quite understand all of the nuances of getting to production and getting the necessary material and process certifications.”

Bill Bihlman, president of Aerolytics LLC, an aerospace market research and consulting firm, says there are four fundamental stages to developing new aircraft and each one is arduous.

• Functional Prototype – The first step is to build an aerodynamically stable prototype that can fly. “I don’t care what you build it out of. Build it out of balsa wood if you want,” says Bihlman. “The focus is proving that your concept is viable. But as soon as you check that box, you move onto the next round.”
• Type Certificate – The second step is receiving type certification. One of the Federal Aviation Administration’s 14 CFR Part 21 certifications, the certificate approves the design of a new aircraft and all component parts, such as propellors and engines. It indicates that the design complies with airworthiness, noise, fuel venting and exhaust emission standards.
• Production Certificate – “The production certificate, which is an extension of the type certificate, is all about quality control,” says Bihlman. “Put simply, it indicates that what you built the first time you are going to build a thousand times.” The certificate signifies that a company can repeatedly manufacture a product or article that conforms to the FAA-approved type design.
• Sustainment – During the final stage, companies prove continued airworthiness of the new aircraft, including development of a maintenance and repair strategy.
• Materials and processes are key to all four steps.
• In Pursuit of the Right Solution
• “The advanced air mobility business model requires both manufacturing and materials excellence,” says Bihlman.
• CFRP is commonly used in traditional aerospace applications, and it has become the standard for AAM. Using hand lay-up to fabricate prototypes from carbon fiber and thermoset resins works, but it presents roadblocks for high-rate production.
• “You need an automated tooling and material system, which is not in place right now,” says Bihlman. “Instead of taking six to eight hours for autoclave curing we need to cure parts in minutes.”
• Dana Jensen, a senior industrial policy analyst with the U.S. Air Force/Agility Prime, asserts that thermoplastic composites will need to be part of eVTOL solutions.
• “Thermosets are not going to go away. It’s not a question of moving from one to the other. It’s about incorporating thermoplastics on a bigger scale,” says Jensen. “If you want to achieve high rates, then you need to move to thermoplastics. And there aren’t many qualified thermoplastic materials out there.”
• It’s a monumental task to create a working prototype, one that many companies have achieved. But if a prototype built with conventional thermosets earns type certification, the company may need to go back to the drawing board to re-imagine the aircraft using thermoplastic composites or quick set thermosets to achieve production certification.
• “How do you move from one material to another without having to go back and redesign the part?” says Jensen. “The more closely the prototype material and tooling resembles what you will use for production the better.”
• The crux for eVTOL aircraft manufacturers is hitting on the right combination of materials, production tooling and automated processes. “We can do all this with engineered materials, but it’s very nuanced,” says Bihlman. “It takes a while.”
• One Company’s Path
• One company striving to find that right combination is Joby Aviation, which has set an ambitious goal of launching an air taxi service in 2024. Its pre-production prototype began flight testing in 2019 and logged more than 5,300 miles last year. A second prototype received FAA Special Airworthiness Certification for experimental research and development in late 2021. It also earned U.S. Air Force airworthiness approval, allowing the company to fly its aircraft as an Agility Prime contractor.
• Joby’s prototypes incorporate high-end thermoset composite materials throughout the vehicle structure, propulsion systems and interior components. The company used conventional manufacturing processes for the prototypes, including hand lay-up and autoclave curing, and has added two automated fiber placement machines to help support pilot plant volumes.
• In 2019, Toyota invested $394 million in Joby Aviation and began sharing expertise on high-volume production.
• “Toyota’s investment has allowed us to work closely on manufacturing and engineering processes, from the design of tools to the layout of our production facility,” says Walker-Jones. The automaker also worked alongside Joby to design a 580,000-square-foot pilot production facility in Marina, Calif., that it plans to open in two phases.
• Joby began its FAA certification program in 2018 when it applied for type certification, which it hopes to complete in 2023. In March, the company moved closer to that goal when it submitted its first area-specific certification plan to the FAA. The plan details the design reports, analysis and testing Joby will employ to demonstrate compliance with FAA safety standards in one functional area of the aircraft – cabin safety.
• It Takes Teamwork
• The technical prowess, time and resources required to develop, certify and commercialize an eVTOL necessitate collaboration. In addition to Toyota, Joby Aviation partners with Uber, Toray Advanced Composites, Garmin and others. The Agility Prime program was structured to foster relationships with academia, industry and investors.
• “The traditional government procurement process is requirements driven, while Agility Prime attempts to turn this model on its head,” says Jensen. “We don’t have a requirement for these new vehicles being built, but we think they could be useful. So, we’re going to help advanced air mobility succeed commercially, then come back on the back end and do procurement.”
• The Air Force can provide corporate partners with capabilities such as wind tunnels, acoustic testing and flight test planning, as well as expertise in areas such as computational fluid dynamics. It has awarded more than $100 million in contracts and a handful of companies have earned military worthiness, including Joby, BETA Technologies and Kittyhawk. More contracts and certifications are sure to come.
• “We didn’t specify a sunset for this,” says Jensen. “Agility Prime is now a program of record, and we are taking new applications on a rolling basis as companies start to mature and fly.”
• While the Air Force has no immediate plans for eVTOL vehicles, a study it conducted with MIT indicated where the new aircraft would complement the military branch’s portfolio of capabilities.
• “We don’t anticipate they will operate in highly contested environments,” says Jensen. “But there’s a lot that eVTOL aircraft can do in terms of logistical support and movement of personnel in uncontested areas or ship-to-shore transport.”
• Early Applications for eVTOLs
• Despite the challenges to implementation, the advanced air mobility market is generating a lot of enthusiasm, as well as speculation over when the first vehicles will take flight and in what capacity.
• “It’s incredibly exciting and in some ways a little unnerving,” says Sherman. “But I’m confident that teams are pulling together – and pulling in the same direction – trying to achieve a 2024 commercial introduction of air taxis.” He suspects that air taxi service will be limited at the outset. Jensen agrees.
• “I don’t think there will be thousands of air taxis swarming around cities – at least not initially,” he says. Jensen cites the prohibitive cost per mile for air taxi commuting and hurdles with insuring eVTOL aircraft as primary inhibitors to near-term adoption. However, he and Sherman both envision other potential early applications, such as cargo and medical transport.
• “If you could put a first responder in a single-seat eVTOL with some drugs and an automatic external defibrillator to respond to cardiac arrest cases where time is everything, you could save tens of thousands of lives a year,” says Jensen, citing a study from MIT.
• Bihlman shares Jensen’s conservative stance on AAM, envisioning commercial introduction between 2028 and 2030. In addition to vehicle development, the accompanying infrastructure to support eVTOL aircraft must be created. But he doesn’t want to discourage innovators, adding, “The AAM market will happen.”
• Suppliers and manufacturers need to be prepared.
• “Being proactive in getting materials and production certified will be key,” says Sherman. “The companies that can show that are going to have the most orders to start with.”
• Susan Keen Flynn is managing editor of Composites Manufacturing magazine. Email comments to sflynn@keenconcepts.net.