https://newatlas.com/aircraft/otto-zeroavia-celera-hydrogen

World's most efficient passenger plane gets hydrogen powertrain
By Loz Blain
June 15, 2022

The entire shape is designed for extreme efficiency, and as a result Otto
says the Celera uses an astonishing 80% less fuel than a comparably sized
jet
The entire shape is designed for extreme efficiency, and as a result Otto
says the Celera uses an astonishing 80% less fuel than a comparably sized
jetOtto Aviation
VIEW 7 IMAGES

The Celera 500L is a truly remarkable design. Otto Aviation says its odd
shape delivers an astonishing 59 percent reduction in drag, and a massive
leap in efficiency and range compared to traditional plane geometries.
Arguably, this thing should've been electric from the get-go, so it's a
no-brainer that Otto has teamed up with ZeroAvia to build a version with a
hydrogen fuel cell powertrain.

Otto claims the Celera 500L in standard fossil fuel-propelled form is "the
most fuel-efficient, commercially viable business aircraft in the world."
Its "flying suppository" shape might not win it any fashion awards, but if
true beauty lies in perfect function, then this thing could be a bulbous
supermodel.
https://newatlas.com/aircraft/bullet-plane-otto-celera-500l/?itm_source=newatlas&itm_medium=article-body

The whole thing is designed to maximize laminar flow – smooth layers of
airflow with little to no mixing of adjacent layers moving at different
speeds. This avoids the swirls and eddies that lead to air turbulence at
speed, causing aerodynamic drag and wasted energy. Laminar flow is by no
means a new concept, but Otto says it's pushed the idea so far forward with
the Celera design that it uses 80 percent less fuel than a traditional
design. No, that's not a typo.

Otto Aviation's Celera 500L prototype in flight: the world's most efficient
passenger aircraft design by a country mile
Otto Aviation's Celera 500L prototype in flight: the world's most efficient
passenger aircraft design by a country mileOtto Aviation
Running on an efficient 550-horsepower combustion engine, Otto claims this
thing will fly six passengers up to 4,500 nautical miles (8,334 km) at
cruise speeds over 460 mph (740 km/h), challenging small business jets for
top speed while more than doubling their range. An impressive glide ratio of
22:1 allows pilots to switch off the engine altogether and glide for up to
120 miles (200 km) completely unpowered. This monster efficiency factor,
says Otto, should make the Celera some 5-7 times cheaper to run than a
comparable jet.

Mind you, it wont scale up to full-size airliner size, since the low-drag
laminar flow model relies on a width-to-length ratio that'd be impractical
in a bigger bird. But Otto says it'll scale up to take 19 passengers, and
there are plenty of markets that could make use of an efficient airframe in
the 6-19 passenger space.

It's not a pie-in-the-sky render, either. Otto has built a full-scale
prototype, and by November last year the company announced it had completed
some 55 successful test flights, reaching speeds over 250 mph (400 km/h) and
altitudes up to 15,000 ft, and that "all test flights have validated the
aircraft's operating performance goals." You can see the thing flying in a
video below.
https://static1.squarespace.com/static/5f3541f19bb2e80bcd4b0f98/t/6195357ffe1a8c086097718b/1637168511672/Otto+Aviation+Celera+500L%2C+55+Successful+Test+Flights%2C+November+2021.pdf

Otto Celera 500L
Now clearly, an 80 percent reduction in fossil fuel use is an environmental
win in and of itself. But if there's one sector in aviation that's crying
out for brain-busting efficiency figures like the Celera promises, it's the
emerging zero-emissions sector, which is currently struggling against poor
range figures thanks to the low energy density of lithium batteries.

Indeed, when we first wrote about the Celera 500L back in 2020, many
questioned why the heck this thing wasn't electric from the get go. And it
seems Otto is on board with the idea, as it's now announced a collaboration
with hydrogen aviation pioneers ZeroAvia to develop a fuel cell-electric
powertrain specific to the Celera's requirements.

This airframe's bulbous shape works well with a hydrogen concept – hydrogen
powertrains can weigh much less than battery-electric ones, but they tend to
take up a bit of space. Still, ZeroAvia is being relatively humble with its
ambitions to begin with, aiming for a range of just 1,000 nautical miles
(1,852 km) of zero-emissions range for a hydrogen-fueled Celera. Still,
that's a very useful distance, and pretty extraordinary for a clean electric
passenger plane.

The Celera flies on a single pusher prop
The Celera flies on a single pusher propOtto Aviation
ZeroAvia is champing at the bit; this could be the company's first chance to
work on a brand-new aircraft design. “The majority of our commercial deals
to date," says founder and CEO Val Miftakhov in a press release, "have
focused on retrofit and line-fit for existing airframes, which is essential
to deliver zero-emission flight to market as quickly as possible. 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.”

Of course, there's a downside to working on brand-new airframes too. It's
one thing to build a prototype and do flight testing, and another altogether
to get an aircraft certified and ready for volume production – particularly
one that deviates from the norm.

Otto has made remarkable progress thus far, and if the company's efficiency
claims are true – which will remain a hotly debated topic on aviation forums
until Otto puts extraordinary proof beside its extraordinary claims – this
does feel like an important aircraft that the world needs right now. Even
the fossil-fueled version could be exceptionally useful for passenger and
cargo operations, and could make a significant contribution to
decarbonization.

But the next steps will be a huge challenge, requiring a ton of long-horizon
investment. We hope Otto's team is fortified and ready for the grind ahead,
and all jokes aside, we wish them all the best. We'd hate to see this flying
suppository get shelved.

Source: ZeroAvia / Otto Aviation
https://ottoaviation.com/
https://www.zeroavia.com/otto-aviation