[HN Gopher] Launch HN: Stralis (YC W23) - Hydrogen electric airc...
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Launch HN: Stralis (YC W23) - Hydrogen electric aircraft for
medium-haul travel
Hi HN, we are Bob and Stuart from Stralis Aircraft
(https://stralis.aero). We're taking advantage of hydrogen electric
propulsion technology to design a low cost, 50-seat aircraft that
can replace a significant portion of the ubiquitous single-aisle
(e.g. Boeing 737) market that makes up ~60% of commercial aircraft
sold. We are starting out by developing the propulsion system for a
6-seat Beechcraft Bonanza. So far, we have installed and tested the
electric motor and performed some benchtop fuel cell testing.
Here's a quick video showing what it looks like these days:
https://vimeo.com/879966330. Next step is to perform some system
testing with a COTS fuel cell, whilst we progress our own fuel cell
development. We are currently working through setting up our
hydrogen electric propulsion test lab at Brisbane International
Airport, which will allow us to rapidly prototype subsystems and
generate the data we need for the 50 seat, SA-1, design. Quick fly
through video of our facility here: https://vimeo.com/884325165
Airlines are anticipating the need to de-carbonise, driven by
legislation or by customer pressure, but there is not yet any
emission-free aircraft solution that is practical and cost-
effective to adopt. Other solutions are either too heavy, like
batteries and automotive industry fuel cells, or too expensive and
inefficient, like sustainable aviation fuel. It is important to get
a low enough CASM (Cost per Available Seat Mile) to allow operators
to switch to a sustainable solution without having to dramatically
increase ticket prices. Bob and I met at a company called magniX,
who develop high specific power electric motors. magniX quickly
identified aerospace as a major market for their technology but at
the time, most of the customers were working on battery electric
solutions for de-carbonizing air travel. We were personally
involved in 3 aircraft platforms (that have flown) that used our
motors. Whilst we are super proud of what we achieved and
overcoming the technical hurdles to fly those planes, it became
clear that batteries were never going to be the solution to de-
carbonising a significant portion of air travel. We went on to work
at a few different sustainable aviation companies, and slowly
became convinced that hydrogen would be the only technology that
would have a chance of achieving the goal of sustainable aviation.
There is a lot of public discourse on what is the best technology
to solve this high-stakes problem, but instead of arguing about
what can and can't work, we decided it would be best to dive into
the technology and give our best go at what we think has the best
chance. Our propulsion system is quite straightforward--we carry
liquid hydrogen in a composite, vacuum insulated storage tank. We
boil off the hydrogen and feed it into the fuel cell. We take air
from outside the plane to supply the fuel cell with oxygen.
Hydrogen and oxygen react in the fuel cell and produce electricity,
with water vapor being the only by-product. The electricity then
powers a lightweight electric motor that spins a propeller. Unlike
most other fuel cell systems, we use the oxygen supply air to cool
the fuel cell as well -- removing the need for large, heavy and
draggy external heat exchangers. This is achieved through our
choice of fuel cell membrane with a much higher operating
temperature (180 C). We remove the weight of the heat exchangers
but also reduce the weight of the propulsion system as we don't
need to overcome the extra drag created by the radiators. All of
this combines to reduce the fuel cell system weight by about 40%,
which equates to a doubling of our payload capacity and, therefore,
half the CASM, when compared to a conventional PEM fuel cell
system. In addition to our tech, we are also approaching the
market differently. We think that a 50-seat aircraft is the optimum
size for an aircraft with our hydrogen electric propulsion. This is
different from conventional turbofan technology where the optimum
size appears to be about 200 seats. All of our competitors are
working towards a family of aircraft going upwards of 200 seats
(Airbus are only focusing on larger aircraft) but we think there
are diminishing returns from building larger hydrogen electric
aircraft. Instead, we are honing in on a 50-seat design, optimized
for hydrogen electric and designed with automotive manufacture
methods in mind. There could be a market demand for up to 50,000
aircraft within the next 25 years, driven by more efficient, point-
to-point routes. Most other aircraft programs deliver around 1,000
units, which generally doesn't warrant a large amount of
automation, and keeps unit costs high. Hydrogen fuel cells are not
new, but we think the need to de-carbonise, the reduction in
renewable energy costs, and the improvement in component
technologies such as motors, power electronics, batteries etc. make
today the best time to pursue this solution to sustainable air
travel. We would love to hear from any of you who have worked in
aerospace, sustainable aviation fuel (the biggest alternative to
hydrogen) and the hydrogen industry. We would also like to hear
from people who fly often, and airlines, to learn how important a
switch to a sustainable solution is to you. Looking forward to
reading all the comments!
Author : stuart8ol
Score : 64 points
Date : 2023-11-20 19:47 UTC (3 hours ago)
| jmoorebeek wrote:
| This sounds like a great proposal, and those 50-seat aircraft are
| the backbone of the mountain communities I grew up around in the
| PNW. Is there any loss in effectiveness in using standard
| atmospheric air (thanks to N2 and other non-oxygen components of
| air)? What do you do with the resultant H2O when the reaction is
| complete?
| stuart8ol wrote:
| Yeah using standard air gives you a performance hit - but it is
| preferred to carrying around pure oxygen from a weight
| standpoint. We just exhaust the H20 from the aircraft. There
| are other things you can do, such as condense and capture, but
| everything comes with a performance hit that we don't think is
| worth it.
| p1mrx wrote:
| > Is there any loss in effectiveness in using standard
| atmospheric air
|
| > What do you do with the resultant H2O
|
| I can't imagine why an aircraft would ever want to carry its
| own oxygen supply, and capture the byproduct. Oxygen is
| _heavy_. Are you thinking of a spacecraft?
| aavci wrote:
| Really cool!
| mysterydip wrote:
| What kinds of costs (time/$) is FAA certification projected to
| add? I assume there's going to be a lot of scrutiny around a new
| (for flight) engine tech.
| stuart8ol wrote:
| Yeah certification is one of our biggest risks. Luckily for us
| there are already a few other companies that are breaking the
| ground here and the certification path is becoming less opaque.
| There is a lot of scrutiny for new propulsion types but the
| certification process is largely the same - its more that we
| don't have the luxury of experience and being able to point to
| "similarity" to show compliance. We are budgeting ~$50M for our
| 15-seat retrofit product development and cert and a bit more
| than 10X that for the 50 seat product.
| mysterydip wrote:
| Are you able to use an "experimental" aircraft/designation to
| do flight tests in parallel waiting for approvals?
| stuart8ol wrote:
| Exactly! We will be flying "Bonnie" our Beechcraft Bonanza
| on an experimental ticket next year. We will then do the
| same for each of other programs. This helps us get the
| hours and data to support our certification process.
| mysterydip wrote:
| Awesome, thanks for the info! Very exciting project, good
| luck!
| rushingcreek wrote:
| This is amazing. I hope you succeed. Using hydrogen fuel cells
| seems like a clever way to get around the thrust/weight issues
| present in electric aircraft with heavy batteries.
| stuart8ol wrote:
| Thank you! If batteries were 10X lighter than they are today,
| then we would definitely prefer them.
| rushingcreek wrote:
| Makes sense. Another potentially interesting factor is that
| the max takeoff weight of a plane can be much higher than the
| max landing weight. If the plane is powered by conventional
| jet fuel, it can take on this extra fuel, fly father, and
| land much lighter than it took off.
|
| Will the relatively constant weight of a hydrogen cell become
| a significant range limitation? Battery-powered aircraft have
| this problem as well. Very curious to hear your thoughts.
| stuart8ol wrote:
| It is definitely a design constraint that we have to
| consider but at the same time the relatively small change
| in weight during the flight is also good for our balance,
| given we won't be putting the fuel in the wings. All in
| all, the sources of weight are pretty different between the
| conventional jet-kerosene versus our hydrogen electric
| propulsion, which is what is driving us to a clean sheet
| design to take maximum advantage of HEP. We are doing a
| 15-seat retrofit of a Beech 1900D as our first product, and
| while it is a great MVP, the landing weight constraint,
| amongst others, make it a little less capable, with 800km
| range, than the conventional version.
| ActorNightly wrote:
| Why hydrogen electric and not hydrogen combustion directly?
| stuart8ol wrote:
| There is definitely advantages of both. Direct combustion gets
| you a much greater specific power of propulsion, and the
| technology for turbine engines is so optimised that it sounds
| like a really attractive option. We expect we can get higher
| efficiency with fuel cells and the engine maintenance costs
| will be lower as fuel cells and electric motors operate at low
| temperature. Both of these cost drivers lead to a lower CASM.
| jltsiren wrote:
| Maybe this is a big-city perspective, but I've understood that
| the main constraint driving aircraft size is runway capacity
| during peak hours. Airports already require a lot of land for
| handling a relatively small number of passengers. As building
| additional runways is often not feasible, the only way to
| increase passenger capacity is using bigger aircraft.
|
| I fly between Helsinki and London often enough. On that route,
| the aircraft is typically either an A320 or an A350.
| stuart8ol wrote:
| Yeah there will be some slot constrained routes that will
| certainly need to stick to the larger aircraft sizes, but many
| that can benefit from the flexibility of a smaller aircraft
| size if the operating cost was low enough. There are second
| city airport and regional routes that would benefit from the
| smaller plane size, as well as the market that is currently
| served by these types of planes - Asia pacific is one example
| of a growing turboprop market.
| w10-1 wrote:
| What are the runway requirements?
|
| Can you comment on why not go down e.g., to a 10-passenger like
| the Pilatus (that lands on a 3000' runway)? It seems like the
| smaller planes straddle the private/commercial line, while a
| 50-passenger plane commits you to airline buyers. (i.e., even if
| not optimal for hydrogen electric, would a smaller-capacity
| target market be more commercially viable and diversify the risk
| of long-term development?)
| stuart8ol wrote:
| We will be basing our requirements broadly on the current
| Dash8-300, so we are targeting around 4000ft for the SA-1, but
| we still have a lot of work before that is validated. It is
| desirable for us to go with smaller planes as it is faster to
| market, much lower program costs but we just don't feel that it
| will have the same impact - both as a business and on carbon
| emissions. As you go smaller, some costs increase per
| passenger, like crew and engine maintenance start to dominate
| at that <12 seat size, and whilst the Pilatus PC-12 is a hugely
| popular plane, its just not something that could compete with
| the major single-aisle market. Accessing this market is what
| would give us the edge and really allow us to build an
| unusually high number of planes.
| scythe wrote:
| I can't help but notice the resemblance to https://h2fly.de/ --
| do you have any major differentiators in mind, or are you
| planning to try to beat them head-on?
| stuart8ol wrote:
| We watch H2fly in very carefully! They are a really impressive
| company and their recent flight with liquid hydrogen is
| inspirational, and really motivates us. I believe we have some
| different fuel cell technology but the main difference is that
| we plan to develop the SA-1 as a clean sheet air frame that
| will be optimised for this new fuel type and propulsion system.
| H2fly are aiming to sell propulsion systems, perhaps we could
| be partners one day if their system performs better than ours.
| breischl wrote:
| News articles frequently say that lack of aircrew availability is
| a major cost and constraint for air travel currently. Wouldn't
| moving to smaller aircraft exacerbate that issue? Or do you think
| it won't be a problem?
| stuart8ol wrote:
| Did someone say autonomous flight?? only kidding, we are not
| pursuing autonomous flight in the near future. It is something
| we hear a lot about too, especially after COVID. I am not sure
| what the answer is here but we do see it as a temporary thing
| and expect that the market will sort itself out. Whilst fully
| autonomous flight may not be our focus, we hope to do some
| things that can reduce the workload of the pilot and perhaps
| help reduce the training burden of crew making the pathway to
| that career more attractive. We are actually co-located with
| Australia's biggest Aviation training provider so we receive a
| lot of feedback in this regard.
| hyperthesis wrote:
| [Maybe disregard this, as I'm not your requested audience, and I
| realize this is a tech/biz post to HN and you are deep in the
| details of confronting the unknown, but...] I think for pitch-
| deck/public communication, as soon as you say "hydrogen
| aircraft", immediately address or at least acknowledge "what
| could possibly go wrong-Hindenburg" and "why not batteries" (not
| para 3).
|
| BTW The first solar+battery electric aircraft world-
| circumnavigation got hardly any publicity, which puzzled me
| https://en.wikipedia.org
| https://news.ycombinator.com/item?id=9824570/wiki/Solar_Impu...
| stuart8ol wrote:
| Thanks - I hear you, safety around hydrogen is always a big
| concern. We do address it head on often but it will always come
| up in any conversation about it. The "why not batteries?
| question is audience dependent - some people have given up on
| batteries and others, they see that it works for EVs so expect
| it to work for aircraft too. Will keep your feedback in mind,
| especially for sales!
| icy_deadposts wrote:
| Will you use electric motor from your previous company magnix?
| how do those motors compare to this other YC company h3x that is
| making electric motors for planes?
| https://news.ycombinator.com/item?id=26224709
| stuart8ol wrote:
| Not this time around! We have selected H3X as our supplier for
| the motor for our tech demo and have signed an LOI for them to
| supply motors for our B1900D-HE retrofit aircraft. I would say
| that magniX has a more mature product and is further along the
| path to certification and its flown many of the recent and
| impressive electric aircraft first flights, including our
| competitor Universal Hydrogen. I'll always have a soft spot for
| the magni650, but at the end of the day, weight is critical on
| an aircraft and H3X are showing us a lighter product. We have a
| good relationship with H3X and have confidence that they will
| be able to meet the cert criteria in our timelines.
| c_o_n_v_e_x wrote:
| What kind of FCs will you be using?
| stuart8ol wrote:
| We can't share too much detail but it has higher operating
| temperatures (180C) than the standard PEM fuel cells that are
| typically used in automotive. This is key to a good aircraft
| solution.
| psadri wrote:
| I wonder what the sweet spot for # of passenger for a given route
| is. You need to balance costs (crew, fuel, airport fees, ...)
| with revenue from passengers. On one end you can have a massive
| plane that flies once a week. But that's inconvenient for
| passengers who'd prefer more frequent flights. On the other end
| you frequently fly tiny aircraft... but that would have a high
| crew + airport fees overhead.
| phkahler wrote:
| I always question if fuel cell / electric is really better than
| just burning the hydrogen in an engine.
|
| We worked on an electric compressor motor for a fuel cell vehicle
| project once and it took more than one kilowatt (maybe 2 or 3 I
| don't recall) to run the compressor. An EV can do highway driving
| at a few KW so that seemed really inefficient. Aircraft run at
| higher continuous power so maybe it makes more sense, but I still
| wonder.
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(page generated 2023-11-20 23:00 UTC)