World’s most fuel-efficient passenger aircraft gets hydrogen powertrain

Otto Aviation Celera 500L
Otto claims an astounding 80% fuel reduction for the uniquely designed Celera, compared to a similar-sized jet. Images © Otto Aviation

When the aviation industry contemplates efficient flight, the name Otto Aviation is likely to rise to the forefront. Otto Aviation, the company behind the Celera 500L, is reshaping the way we envision efficient, eco-friendly air travel. The Celera 500L, with its distinct bullet-like shape, delivers an exceptional 59 percent reduction in drag and a significant enhancement in efficiency and range compared to conventional plane designs. A recent collaboration with ZeroAvia further propels this innovation by introducing a hydrogen fuel cell powertrain to this groundbreaking aircraft.

The Celera 500L, even in its original, fossil fuel-propelled form, has claimed to be the “most fuel-efficient, commercially viable business aircraft in the world.” The aircraft’s form may not meet conventional aesthetic standards, yet if the measure of beauty is function, the Celera 500L is a marvel of engineering and design efficiency.

The design innovation driving this aerodynamic efficacy lies in the maximization of laminar flow, a concept that has long been a part of the aviation design discourse. Laminar flow entails smooth layers of airflow with minimal mixing between adjacent layers moving at different speeds. This reduces air turbulence at speed, limiting aerodynamic drag and conserving energy. Otto Aviation says its Celera design exploits laminar flow to such a degree that it uses 80 percent less fuel than traditional designs – a figure that’s hard to ignore.

At the heart of the Celera 500L is a highly efficient 550-horsepower combustion engine. This engine can power a flight carrying six passengers up to 4,500 nautical miles (8,334 km) at cruise speeds exceeding 460 mph (740 km/h). Such a performance presents a direct challenge to small business jets in terms of top speed while offering more than twice their range. Adding to its performance prowess is an impressive glide ratio of 22:1, which enables pilots to switch off the engine and glide up to 120 miles (200 km) without power. Consequently, Otto estimates the Celera 500L will be 5-7 times cheaper to run than a comparable jet.

Otto Aviation Celera 500L Maximizing Laminar Flow
Otto Aviation’s Celera 500L, with its unique design optimized for laminar flow, reportedly cuts drag by a staggering 59% compared to conventional aircraft, making it the world’s most efficient passenger plane.

However, the Celera 500L isn’t designed to rival full-size airliners. Its low-drag laminar flow model requires a width-to-length ratio that would be impractical for larger aircraft. Yet Otto Aviation has indicated the design could accommodate up to 19 passengers, potentially serving a niche market in the 6-19 passenger space.

This isn’t simply theoretical postulation. Otto Aviation has built a full-scale prototype and reported 55 successful test flights by November of the previous year. These flights reached speeds exceeding 250 mph (400 km/h) and altitudes up to 15,000 feet. The company confidently states that these tests have validated their performance goals.

Otto Aviation Celera 500L In Flight
Otto Aviation’s Celera 500L in flight: a prototype that redefines efficiency in passenger aircraft design.

However, an 80 percent reduction in fossil fuel use is just the start. The aviation industry’s nascent zero-emissions sector stands to benefit enormously from efficiency figures like those promised by the Celera. The industry currently grapples with the low energy density of lithium batteries, limiting the range of electric planes.

This is where ZeroAvia comes in. The hydrogen aviation pioneer has partnered with Otto to develop a fuel cell-electric powertrain tailored to the Celera 500L’s specifications. The aircraft’s design suits a hydrogen concept – hydrogen powertrains can weigh much less than battery-electric ones, though they require more space. The collaboration’s initial goal is a range of 1,000 nautical miles (1,852 km) of zero-emissions flight for a hydrogen-fueled Celera 500L.

Otto Aviation Celera 500L In Flight
The Celera 500L prototype in flight.

ZeroAvia’s founder and CEO, Val Miftakhov, in a recent press release, stated, “The majority of our commercial deals to date have focused on retrofit and line-fit for existing airframes…However, efficiency gains from new airframe design can expand the impact of zero-emission aviation. We are pleased to collaborate with innovators, like Otto Aviation, bringing cutting-edge clean sheet designs to market as we can optimize the hydrogen-electric propulsion system for those designs.”

While the prospective impact of the Celera 500L on zero-emissions aviation is promising, the road to realization is not without hurdles. Building a prototype and conducting flight tests are initial steps in the process. Achieving aircraft certification and preparing for mass production—especially for an aircraft that deviates significantly from conventional design—is a more daunting task.

Otto Aviation Celera 500L Single Pusher Propeller
The Celera operates with a solitary pusher propeller.

Otto Aviation’s journey so far has been remarkable, and if the company’s claims about the Celera 500L’s efficiency hold true, this aircraft may be precisely what the aviation industry needs in this era of environmental awareness. Even the fossil fuel version of the aircraft could play a substantial role in decarbonizing passenger and cargo operations.

However, the next phase in this journey presents considerable challenges, requiring significant long-horizon investment. If Otto Aviation can overcome these hurdles and bring this hydrogen-powered aircraft to market, it could represent a significant leap forward in the quest for environmentally friendly, efficient air travel. It’s certainly an endeavor that warrants attention from all corners of the industry.

Otto Aviation Celera 500L ZeroAvia Hydrogen
ZeroAvia relishes the chance to develop a fresh airframe instead of adapting existing aircraft.

Source: Otto Aviation / ZeroAvia