• • • ELECTRICAL DESIGN SOFTWARE • • •
THE FUTURE OF FLIGHT IS NEARLY UPON US
Whilst many still consider urban air mobility (UAM) the stuff of sci-fi movies like Blade Runner the reality is getting ever closer and it looks like 2024 will be the year to watch, says David Latimer, chief executive of Magnomatics
he market for UAM is attracting increased investment. On August 11, 2021, Joby Aviation listed on the New York Stock Exchange with a valuation of US$4.5 billion (£3.3bn).
T
The California-based company developing all-elec- tric aircraft for aerial ridesharing now considers it is has sufficient cash (US$1.6 billion) to fund it to initial commercial operations. It has completed over 1,000 test flights and has agreed a path to G1 certification of the aircraft with the FAA.
The company has also taken the first steps toward becoming the first eVTOL airline with application for Part 135 Air Carrier Certificate issued by the FAA. Joby expect to start operations of their quiet, all elec- tric aircraft with pilot and four passengers in 2024, creating possibly the first EVTOL airline. Joby is not alone. Palo Alto-based Archer Aviation (value US$1.5bn) unveiled its Maker aircraft in June 2021. It too plans to be in service by 2024. Another notable player in the USA is Wisk, which was born out of Google co-founder Larry Page’s Kitty Hawk and Boeing. The involvement of Boeing, however, is now in some doubt following the closure of its Boeing NeXT innovation on the back of the losses resulting from the 737 Max grounding.
Meanwhile in Europe, Munich-based Lilium is work- ing towards joint EASA and FAA certification of its seven-seater aircraft also by 2024. It has announced its intention to list on NASDAQ.
German rivals Volocopter is also targeting first com- mercial operations in two to three years. In June 2021, UK-based Vertical Aerospace announced it is to list in the US with a US$2.2 bn SPAC deal on the basis of pre-orders of up to 1,000 aircraft with a total value of up to $4bn.
Like Volocopter, Vertical Aerospace has set its sights on the 2024 Paris Olympics as a high-profile backdrop for initial commercial operations…and the list goes on.
It is reported by Roland Berger1 that the develop- ment and certification of an UAM aircraft will cost around US$2bn. For the newcomers to the sector, to raise such funds means it is inevitable that much of their activity is relatively public. No doubt the more conventional companies have more clandestine pro- grams on their books.
However, there are some very interesting parallels with the burgeoning electric vehicle market back in 2008. New entrants like Tesla, Coda and Fisker were emerging whilst at the same time the mainstream automotive industry was in crisis, just as now the aer-
ospace industry is hit by COVID-19 and severe travel restrictions.
One common feature is that all these aircraft use multiple electric motors, which makes the perfor- mance density of the motors critical and a key to a performance breakthrough.
In industry technical expert Jonathon Bird’s Review of Electric Aircraft Drivetrain Motor Technology2 he discusses the relative merits of various technologies, examining the continuous performance density of 25 different commercially available motors. Configu- rations include both axial and radial flux machines. Some are air cooled some use liquids. The route to power density in electric machines has historically been to operate permanent magnet mo- tors (PM) at higher speeds, often in excess of 10,000 rpm. To become useful for air mobility aircraft the high speeds need to be geared down by as much as seven times.
Conventionally this introduces the requirement for a mechanical gear box, raising the issues of reliability, wear, maintenance and noise. Tallerico, Cameron, Schiedler and Hasseeb3 have pointed out that the reliability of mechanically gear driven propulsion motors would have to increase four-fold to meet the required safety standard for UAM aircraft. Jonathon Bird introduces the idea of magnetic gears reference torque densities of 49Nm/kg at a scale of 100Nm, close to the torque density of me- chanical gears. He also references the Outer Stator Magnetically Gear Motors (OSMGM) proposed by Tallerico et al.
16 ELECTRICAL ENGINEERING • SEPTEMBER 2021
In an OSMGM, a magnetic gear is integrated with a conventional stator. Crucially by integrating a magnetic gear with a motor the inner high-speed magnetic rotor fulfills two functions. It is both the high-speed rotor of a PM motor and the high-speed rotor of the magnetic gear. This reduces the over- all mass of the OSMGM. Tallerico et al went on to develop a high-fidelity design of an OSMGM with a torque density of >30Nm/kg and > 95% efficiency. They also concluded that this was roughly double what could be achieved using a direct drive electric motor for UAM.
Magnomatics was spun out of the University of Sheffield in 2006 to commercialise technology based on magnetic gears. Among its patented products is the Pseudo Direct Drive (PDD) which is an OSMGM. Whilst being aware of work at NASA the company’s early application priorities have been to develop the technology for offshore wind, marine propulsion and light rail. And it has built a demonstration direct drive 500kW generator for offshore wind with a torque of 200,000 Nm and efficiency in excess of 97%. Magnomatics has been able to successfully license its proprietary PDD technology in the above sectors to blue chip organizations and is now turning its atten- tion to the UAM market, where there is a natural fit for the novel and patented technology. The company is also currently designing UAM propulsion motors based on PDD technology it is believed will outper- form all other machines currently available on the market, with initial demonstration machines due to be operational in 2022.
electricalengieneeringmagazine.co.uk
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44
