Meet Cora

By Mike Hirschberg

Vertiflite May/June 2018

On March 12, Kitty Hawk revealed its latest surprise: Cora. After nearly eight years of secretive electric vertical takeoff and landing (eVTOL) aircraft development, the Mountain View, California-based company backed by Google co-founder Larry Page finally went public.

With the hashtag #MeetCora, Kitty Hawk announced that it had been flying a two-seat derivative of the Zee Aero Z-P2 (see “Electric VTOL News,” Vertiflite March/April 2018) in California and in New Zealand. The company also announced that it had established Zephyr Airworks, the operator of Cora in New Zealand.

Zephyr Airworks was started in December 2016 to be able to test and work with the New Zealand government, the Māori people, business partners and the community. “New Zealand is recognized for its safety-focused regulatory environment and a strong history of excellence in airspace management,” the company states on its website. The company shipped its first air taxi to New Zealand in October 2017 and began testing shortly after that.

Cora was developed by what had been known as Zee Aero, which was originally founded in 2010 by Larry Page. In 2015, he started a separate electric VTOL company, Kitty Hawk. Many of the leading participants at Aerovelo — the Toronto team that won the AHS Igor I. Sikorsky Human Powered Helicopter Competition in 2013 — moved to California to join the new company (see “Back to Kitty Hawk,” Vertiflite, Nov/Dec 2017). Zee became a subsidiary of Kitty Hawk in 2016 and has now evolved into Cora. As the company explains: “Zee Aero was the name of our Cora team while we were in [the] development stage. Now that the Cora prototype is in the market, we wanted a name that reflected the spirit of Kitty Hawk’s mission of bringing everyday flight to everyone.” (The company is separately developing the Kitty Hawk Flyer, a personal amphibious eVTOL aircraft to go on sale later this year.)

Zee History

As covered in prior issues of Vertiflite, Zee Aero developed the Z-P2 full-scale, manned eVTOL aircraft, flying it at Hollister Municipal Airport in California. The effort began in March 2010, originally under the leadership of Prof. Ilan Kroo of Stanford University. Patent 9,242,738 (priority date July 19, 2011) illustrates a high-mounted series of vertically mounted electric propellers similar to the first vehicle, which was given the deceptively dull name, “Proof of Concept” (POC).

The subscale POC made its first unmanned (self-piloted) hover in December 2011 and completed its first transition in February 2014. The aircraft demonstrated flights up to 60 mph (100 km/h) with vertical takeoffs and landings. The aircraft was publicly unveiled by Kitty Hawk CEO Sebastian Thrun (see sidebar) on CNN in December 2017.

Next came the manned Z-P1, which only made conventional takeoffs and landings, and was not pursued further; however, parts were used for a new approach, Z-P2, pursued under the new CEO, Dr. Eric Allison. Although some surreptitious photos of subscale aircraft had leaked out over the years, Steve Eggleston at DK Turbines in Hollister was the first to photograph the Z-P2, catching it as it was being towed out to the runway on Oct. 10, 2016. The aircraft began conducting manned hover testing in March 2017. (For photos and more information, go to the AHS Electric VTOL News website, www.eVTOL.news.)

Based on FAA records, sightings of Z-P2 were originally thought to be the Z-P1. The FAA Registry database for Zee Aero listed N101XZ (model Z-P1) and N102XZ — the POC, with the listed model name of “MUTT”. Thus, many references to the Zee Aero aircraft in Vertiflite and the media erroneously referred to the manned eVTOL model as the Z-P1.

The full-scale manned Z-P2 made its first flight in late 2016. In August 2017, the eVTOL demonstrator made its first “verti-circuit” — from vertical takeoff to efficient, wing-borne flight and back to a vertical landing — which has long been a standard in flight testing of new VTOL concepts. It was for being the first electric VTOL aircraft in the world to demonstrate a verti-circuit to wingborne flight and back that Kitty Hawk was nominated in February for the 2017 Robert J. Collier Award. The six underwing rails each support a fore and aft electric propeller that is only turned on for vertical flight; for cruise, rear propellers accelerate the aircraft until it transitions to the wing, at which time the lifting propellers stop and are indexed to align with the airflow.

This testing of Z-P2 led to the decision to develop the self-piloted two-seat Cora demonstrator. It first flew in California, prior to being testing in New Zealand by Kitty Hawk subsidiary Zephyr Airworks.

Top view of Cora, which shows the 12 canted electric propellers, which stop and align with the streamline flow after transition to wing-borne flight. No photos of this prototype have been released in the air.

Cora

Kitty Hawk began flying Cora (apparently unmanned) in New Zealand in November 2017: “After almost eight years of exploring new frontiers, we had built the aircraft we had been dreaming of: Cora. An electric, autonomous fully fledged air taxi that takes off like a helicopter and flies like a plane. The first step to a world where the freedom of flight belongs to everyone.”

The company is not providing interviews, but Kitty Hawk described some of the features of Cora on its website thusly:

■ Independent Rotors: Because our fans and propellers are electric, they can operate independently. An issue with one has no effect on the others.
■ Triple Redundant Flight-Computer: Cora is equipped with three independent flight-computers that each calculate its location. If there’s an issue with one of them, Cora can still reliably navigate.
■ A parachute: launches if Cora needs to land without its fans.
■ Ease: Cora will use self-flying software combined with human oversight to make flying possible for people without training.
■ Sustainability: Cora is powered by the same kind of technology that helps electric cars contribute to a more sustainable world.

Cora Fact Sheet

  • Company Name: Kitty Hawk Corporation is a California-based company. Zephyr Airworks is the operator of Kitty Hawk in New Zealand.
  • Headquarters: Mountain View, California
  • Kitty Hawk CEO: Sebastian Thrun
  • Zephyr Airworks CEO: Fred Reid
  • Product Name: Cora (prototype)
  • Type of Machine: Air taxi
  • Power: All-electric
  • Capacity: Designed for two passengers
  • Altitude: Operates between 500 ft to 3,000 ft above the ground (150 m to 900 m)
  • Wingspan: 36 ft (11 m)
  • Vertical take-off and landing: Cora is powered by 12 independent lift fans, which enable her to takeoff and land vertically like a helicopter. Therefore, Cora has no need for a runway.
  • Fixed wing flight: On a single propeller
  • Range: Initially about 62 statute miles (100 km)
    Speed: About 110 mph (180 km/h)

It appears that three aircraft have been built. The first prototype in California (N301XZ) was painted all white. The second prototype (N302XZ) has a white fuselage with green empennage and propeller rails. It was registered in New Zealand with the mark “UZA;” the CAA lists it as the “Zephyr Airworks Mule SPA” with Serial No. 002 and a gross weight of 2,700 lb (1,224 kg). Other photos show a third aircraft with the opposite paint scheme — green fuselage with white tail and underwing rails; it was shown in California with the allwhite N301XZ, but no photos were shown of it in the air.

Welcome to New Zealand!

New Zealand might at first seem a curious choice. But, the country has one of the world’s most sustainable energy ecosystems, with 80% of the country powered by renewable energy. And now they are looking to harness the benefits of the electric mobility revolution.

According to Kitty Hawk, New Zealand is also recognized for its safety-focused regulatory environment and a strong history of excellence in airspace management: “These qualities are vital in giving people confidence that we are serious about making Cora the best air taxi in the market.”

Zephyr Airworks CEO, Fred Reid, remembered the first meeting with the government: “We had no idea what to expect. They could have laughed us out of the room. We were pitching something that sounded like science fiction.”

But Dr. Peter Crabtree of New Zealand’s Ministry of Business, Innovation and Employment (MBIE) saw the opportunity immediately. “In New Zealand, we know we can’t keep using the same old approaches to meet our future challenges. We saw Cora’s potential as a sustainable, efficient and transformative technology that can enrich people’s lives, not only in New Zealand, but ultimately the whole world.” The MBIE, Ministry of Transport, and the Civil Aviation Authority (CAA) were willing to work with the Californians and Zephyr Airworks found “a deeper partnership than we had ever imagined.”

This all-white Cora aircraft, N301XZ, with the Zee Aero logo on the tail, was tested in California near San Francisco beginning in late 2017.
Zee Aero first flew its subscale Proof of Concept MUTT electric VTOL demonstrator in 2011, proving the basic distributed electric propulsion concept, and first transitioned to wing-borne flight in 2014.
In August 2017, the Z-P2 became the first manned eVTOL aircraft in the world to demonstrate a verti-circuit to wing-borne flight and back; it was for this that Kitty Hawk was nominated for the 2017 Collier Award.
New Zealand Prime Minister Jacinda Ardern unveiled the venture on March 13 (NZ time), alongside Kitty Hawk. “I’m really thrilled to see New Zealand endorsed as a place where exciting companies want to do business,” she said. “Innovation is in our DNA — Kiwis love a challenge and pushing the envelope and I think it’s that spirit that resonates with innovators around the world.”

It’s notable that Canterbury, where Zephyr Airworks’ testing is based, is also home to Martin Aircraft Company, which is developing a twin ducted fan, fly-by-wire/ control vane, rotary-engine-powered personal VTOL aircraft, the Martin Jetpack. [Martin’s chief test pilot, Prospero Alexie Uybarreta, is the 2018 winner of the AHS Frederick L. Feinberg Award, which is presented to the pilot or crew of a vertical flight aircraft who demonstrated outstanding skills or achievement during the preceding 18 months. – Ed.]

Christchurch Mayor Lianne Dalziel proclaimed that the Cora project was “a great example of our commitment to be prepared for the future.”

In an email provided to The New York Times, Prime Minister Ardern also said that working with Kitty Hawk/Zephyr Airworks on the eVTOL project was “about sending the message to the world that our doors are open for people with great ideas who want to turn them into reality.” According to the Times, she continued: “We’ve got an ambitious target in New Zealand of being net carbon zero by 2050 … [and] exciting projects like this are part of how we make that happen.”

Zee/Cora eVTOL Development Aircraft

  • POC: Unmanned canard/tail configuration; propellers mounted on two booms along the fuselage. Pusher propeller at the end of each boom. First hover in Dec. 2011. First transition in Feb. 2014.
  • Z-P1: Single seat; configuration unknown. Did not hover.
  • Z-P2: Single seat; high wing/tail; propellers on pylons under the wing. Pusher propellers on the tail. Hover testing began in March 2017. First verti-circuit in Aug. 2017.
  • Cora: Two seat/unpiloted; mid-wing with twin boom tail. Propellers on underwing pylons. 3 aircraft built.

At the same time as the Cora announcement, New Zealand’s Research, Science and Innovation Minister Dr. Megan Woods formally launched the “Innovative Partnership” program, which aims to attract future-focused international innovators and firms to undertake research and development — and develop their products — in New Zealand. The program, led by MBIE, “engages with innovative companies that are pushing the boundaries of technology and solving the world’s big problems, and promotes the compelling advantages of working in New Zealand.”

In the announcement, Woods also stated that: “Zephyr Airworks’ presence in New Zealand will build capability in our own science system,” particularly in areas like software engineering, artificial intelligence, robotics, composite material and aviation design.

Christchurch Mayor Dalziel noted that the city and the surrounding Canterbury region “was the right location due to our physical environment. We have open skies and open spaces, in a beautiful friendly location and we encourage innovation. It’s also because of our connectivity to the rest of the world, with our international air and seaports which collectively makes Christchurch and Canterbury attractive for trialing new technology.” The city is also exploring other transportation innovations, with test projects such as the Yoogo electric car sharing scheme and Omhio autonomous buses and shuttles.

Where To From Here?

Kitty Hawk does not plan to sell Cora aircraft to the public, but rather the aircraft will be a part of a service similar to an airline or a rideshare. Zephyr Airworks wants to begin commercial air taxi operations in the next three to six years.

Kitty Hawk received an experimental airworthiness certificate for Cora from both the FAA and the New Zealand CAA. The CAA is currently working to develop specific certification requirements for Zephyr’s commercial operations. A new Civil Aviation Rule took effect in 2015, which provides a framework for operating unmanned air vehicles (UAS), and is seen as a potential basis for Cora. The company said, “we are working with the CAA on further certification goals to bring an air taxi service to the commercial market.”

Right now, the company is head down in developing Cora for the New Zealand market: “We have a lot of work to do and we are working constructively with regulatory authorities. We are looking forward to being able to share our product with the New Zealand public when the time is right.”

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