Launch HN: Stralis (YC W23) – Hydrogen electric aircraft for medium-haul travel

124 points15 hours

Hi HN, we are Bob and Stuart from Stralis Aircraft ( 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: 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:

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!

jltsiren14 hours ago

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.

jillesvangurp3 hours ago

That's true for big airplanes. Small ones need a lot less runway. Which means they can land at smaller airports. Some of the electrical VTOL planes under development currently don't need airports at all and can take off from pretty much any flat surface.

The size of jet planes is dictated by fuel cost. Fuel is expensive. Large planes expend it more efficiently. But they are also loud and pollute. So people don't like them too close to where they live. When you use fuel by the thousands of liters per flight, it starts to add up in terms of cost. It's also why private jets are only for rich people. They burn hundreds of liters of expensive fuel per flight. Add to that the maintenance and staffing and you are looking at eye watering amounts per flight.

Hydrogen is of course not cheap currently but it might drop in price substantially as renewable energy gets cheaper. At that point a few smaller planes might be cost competitive with a larger jet fueled plane. But still, there are lots of logistical challenges related to getting large quantities of hydrogen to fuel planes. I doubt it will be very economical or practical any time soon.

My pet theory is actually that most short haul flight will shift to small, autonomous, electrical planes. They'll wipe out three of the largest cost factors in aviation: fuel, staffing, and maintenance cost (much less complex mechanical systems). They'll fly point to point rather than hub to hub; or at least tiny airport close to your origin to tiny airport close to your destination. If you want to fly further, you can just chain a few hops. It will work like an uber pretty much.

Inter continental flight is a different challenge. At least short term it's not feasible to do that with battery electric. Synthetic fuels and hydrogen look promising for that. But I wouldn't discount electric for that either long term. If battery breakthroughs keep on happening and we get some fancy solid state batteries delivering 2000 watt per kg or so, that whole game changes as well.

bobthepanda1 hour ago

Short runways still need to be sited in cities. In a lot of areas airports are already so close together that the airspace is congested with all the conflicting paths and holding patterns; I think the worst example is NYC where Teterboro, JFK, LaGuardia and Newark make the airspace very suboptimal.

stuart8ol14 hours ago

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.

timeon10 hours ago

Airplanes presented here looks like those in private jet category. So these are probably aiming to replace those first?

stuart8ol10 hours ago

We are not really targeting the private or business jet market (though if someone wanted one for this purpose we wouldn't turn them away!). There is another impressive YC company that is that you should check out, Beyond Aero We are really targeting a low cost commercial market - moving people and cargo. The smaller size is driven in part by the technology - with 50 seats being a good size to capture a large proportion of flying traffic - and partly that it will be faster and cheaper to certify and get a smaller aircraft into the market.

phkahler12 hours ago

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.

stuart8ol11 hours ago

Yeah the compressor load goes up with power - we have a 27 kW compressor for our 120kW PEM fuel cell here in the lab (this isn't what is going on the aircraft). This is one of the issues we are tackling with our unique system architecture for the aircraft.

genman9 hours ago

How is the noise difference between electric and combustion engine?

stuart8ol9 hours ago

One thing we have learned on this journey is how much low noise is to our customers and the wider community - we have yet to really put this under test and try and get a cost number against it i.e. how much more would you pay for a quieter engine? What we do have is an opportunity to be much quieter, but there is always a penalty to pay in terms of size. For example, unlike a battery aircraft, we still have to provide the fuel cells with air and we can do that with large quiet ducts or small noisy ones - but larger ones take up valuable real estate and ultimately add weight to the system. What I can say is we will design it to be quieter than current jet engines, but where we draw the line is tbd.

yuppiepuppie4 hours ago

Fwiw, I love flying the B787 for many reasons, one of them being the low noise level. But… I wouldn’t go so far as to pay more money for it. The noise factor is not a decision driver, where seat size/leg room and service definitely are when it comes to choosing an airline/route.

hyperthesis2 hours ago

IIRC for powered paragliders, it turned out propeller noise drowns out ICE noise.

breischl13 hours ago

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?

stuart8ol13 hours ago

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.

w10-114 hours ago

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?)

stuart8ol13 hours ago

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.

rgmerk3 hours ago

Good luck!

I’m curious as to how much of the development of the follow-on ground-up airframe can actually be done in Australia, though. To my knowledge the largest aircraft ever designed in Australia was the GAF Nomad, and that was more than 50 years ago!

Given the sheer scale of specialised engineering skills required, aren’t you going to end up having to have the majority of your engineering staff in the USA and/or Europe?

stuart8ol3 hours ago

We were so close to buying an old Nomad for our tech demo! But we thought if we took it to an airshow, it would only get a small sub-set of attendees excited, compared to a Bonanza, which people seem to love. We would really love to do it all in Australia and think Australia is a great place to do the initial development work, flight testing our tech demo and retrofitting the first set of our B1900D-HE product. But we would, reluctantly, agree with you that the SA-1 design, testing and manufacturing would be at best global but most likely heavily centered in the USA. Its our plan to grow the team in the states, starting soon, and slowly shift the center of gravity as the projects move through maturity.

timthorn3 hours ago

> All of our competitors are working towards a family of aircraft going upwards of 200 seats

Isn't ZeroAvia tackling smaller aircraft?

stuart8ol3 hours ago

They are aiming to be the propulsion system supplier for future aircraft but crucially the are also targeting developing systems for a family of aircraft starting small and are working towards aircraft upwards of 200 seats. Our premise is to not look past 50 seats. If we were to design a 200 seat aircraft its CASM would not be much cheaper than the 50 seat if we aim to do a single aircraft type from the start, then we can aim for much higher volumes than aircraft programs traditionally achieve and ultimately bring our unit costs right down and undercut anyone else working on a family of aircraft.

lambdatronics7 hours ago

Thanks stuart8ol for all the detailed answers in this thread. I learned several new things today (use of compressors for fuel cells to increase power density, logic of airplane sizes). This is the stuff I come to HN for! Also cool to see you using H3X motors - I remember their launch here, I was excited for them.

Good luck decarbonizing aviation!

stuart8ol6 hours ago

My pleasure! Yeah working with the H3X team has been great. We are going to have them out at the airport before the end of the year, letting them run some tests on our set up. Will be fun.

icy_deadposts13 hours ago

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?

stuart8ol12 hours ago

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.

jmoorebeek15 hours ago

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?

stuart8ol14 hours ago

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.

p1mrx13 hours ago

> 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?

Qwertious2 hours ago

>Oxygen is heavy.

More specifically, hydrogen has an atomic weight of 1, whereas oxygen has an atomic weight of 16. For producing H20, that means you would have to carry 8x your hydrogen's weight in oxygen, if you don't use atmospheric oxygen.

stech42152 hours ago

Take a look at They have a hybrid drone/canard design which is VTOL/STOL and achieves the efficiency of wings for distance flying. The propellers are angled at 45 degrees so no complicated tilting mechanism needed. Could be interesting for a clean sheet design.

stuart8ol2 hours ago

Thanks - will definitely take a look.

JCharante4 hours ago

Why is a 50 seater trying ti compete with 737s when 737s have 120-150 pax capacity. It seems like you should compete with ER175s and other regional jets instead. If you’re aiming to compete for thin MH routes then wouldn’t slots at airports be an issue for such thin routes?

stuart8ol3 hours ago

The lowest hanging fruit is the current 50-80 seat turboprop market. Next would be the regional jet market and lastly we want to capture a sizeable portion of the single -aisle market. The reason we want to compete with/capture traffic served by 737s and the like is that the market is enormous - we are estimating $1.7T over the next 20 years if we were to replace single-aisle with our 50-seat, SA-1. The reason that we believe we could compete is because we believe that we could bring the CASM of the 50-seater down to be on par with a 737, and combined with the emission reduction we think that this is compelling offer for airlines. Our aim is not to have to compete with 737s at airports that are slot constrained but to make use of the 100s of underutilised airports across America. By bringing down the CASM of a 50 seater, we believe that this would increase the passenger traffic too and from those airport and make the currently thin routes more profitable.

JCharante30 minutes ago

I see, that makes sense. There's plenty of airlines like Ryan Air and Allegient who operate thin routes to secondary airports. A 50 seater seems perfect for operators who specialize in thin routes. How ironic if budget airlines beat traditional airlines in becoming carbon neeutral.

JCharante4 hours ago

Also, how much air do you need go run the chemical reaction? Will your plane have an APU?

stuart8ol3 hours ago

The air needed for the chemical reaction is pretty small, but we will also be drawing in some air for cooling and that will be around the same order of air that is used by a turbine engine. We will not have an APU per se, but we will have a small amount of battery to start the propulsion system and this can provide power to the aircraft systems for some time. We can also start up the fuel cells if need be to supply extra power, without turning the electric motor and propellers.

JCharante2 hours ago

Thank you so much for these detailed answers! It’s really nice to hear from a professional in the field

psadri12 hours ago

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.

stuart8ol12 hours ago

We think for a high proportion of routes 50 seats for hydrogen electric propulsion. We heard from a major airline that their network planners always want a smaller plane, for flexibility and a high load factor and the fleet planners always want a large plane for lower CASM and fewer aircraft, that tension has basically landed on the single-aisle size (180-200 seats) for most routes with conventional propulsion. But this changes with the technology as different cost drivers have different rates of change with seat count. A good indicative document is, this is asking "if you were to serve the market with only one plane, how many seats should it have?"

aidenn010 hours ago

It seems like if the fuel costs were to go down, you'd want a larger plane, since crew and maintenance costs would make up a larger fraction of the costs?


Looks like the site answers this; reduced maintenance costs when not having a high-temperature turbine are predicted to lead to similar CASM as a 737 despite being about 1/3 the seats.

stuart8ol10 hours ago

I think that is a fair statement. You also have to factor in the capital costs, the aircraft purchase price per seat typically increases with aircraft size so it comes down to the balance there, between that cost increasing and other costs decreasing. The scales can tip either way depending on the circumstances. For a 737, we have that capital costs contribute about 40% of the CASM, whereas Crew is 4% and Maintenance is 16%. In conventional aircraft, the efficiency of larger engines really vs smaller ones really push towards larger aircraft.

stuart8ol12 hours ago

We would love to do the analysis you are describing in detail. I'm thinking getting people movement data from google maps or something, using that to figure out where people are traveling to. Then use that to determine what traffic needs to go through the major airports and who would be better off going to local airports and really map the traffic in detail. Then overlay our cost data to see what is the real optimum. If anyone can help with that we would love to chat!

mysterydip14 hours ago

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.

stuart8ol14 hours ago

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.

mysterydip14 hours ago

Are you able to use an "experimental" aircraft/designation to do flight tests in parallel waiting for approvals?

stuart8ol14 hours ago

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.

mysterydip14 hours ago

Awesome, thanks for the info! Very exciting project, good luck!

hyperthesis13 hours ago

[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).

EDIT you could defer the issue with "Fuel cell electric aircraft"

BTW The first solar+battery electric aircraft world-circumnavigation got hardly any publicity, which puzzled me

EDIT Since I'm already downvoted, I'll add: I wonder about fuel cells for powered paraponts/paragliders, where battery-electric are available, but aren't quite there yet vs petrol, esp for range.

stuart8ol12 hours ago

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!

blonder11 hours ago

Best of luck! I can think of no cooler space to work in than next generation clean aircraft. Now, if only I wasn't completely hopeless at physics and chemistry...

stuart8ol11 hours ago

Thank you, I can confirm it is the coolest job I have had so far, and I have done quite a few cool things. I can also tell you, as someone who studied physics, I have only really spent about 10% of my time in the last year doing any physics! So much other stuff to get through...

rushingcreek14 hours ago

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.

stuart8ol14 hours ago

Thank you! If batteries were 10X lighter than they are today, then we would definitely prefer them.

hebrox3 hours ago

If we ever get to that point, could your 50 seater be easily equipped with that, or would you redesign it from the ground up?

rushingcreek14 hours ago

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.

stuart8ol13 hours ago

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.

genman9 hours ago

I have read that battery based aircraft would start to make sense if batteries were 2-3 times less heavy - do you think that this wouldn't be feasible for some type of aircraft?

stuart8ol9 hours ago

Yeah even with today's batteries there is a business case for battery electric flight. Trainers, short hops across water and intracity + eVTOLs of course all make sense to tackle with battery. This is because the efficiency is good, the cost can be potentially very low and the infrastructure is manageable. But as a solution to decarbonising a large proportion of aviation - it doesn't work. We want to find a solution to serve the enormous number of passengers that fly up to 3000 km. If we can tackle that, we can cut more than 50% of aviation emissions.

ActorNightly14 hours ago

Why hydrogen electric and not hydrogen combustion directly?

stuart8ol14 hours ago

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.

genman9 hours ago

I have seen claimed that the system with battery powered electric engine would become practically maintenance free. Can you comment on this based on your experience? How would fuel cell based system compare to this?

stuart8ol9 hours ago

I think I would be hard pressed to say maintenance free but definitely significantly lower maintenance costs. Turbine blades are intrinsically expensive, made of titanium and operate at high temperatures under high loads. Electric motors have much simpler operation and when made at scale, can really benefit from a replace after 20,000 hours model, instead of a overhaul every 1800 hours, with 200hrs inspection intervals, which we see in some turboprop engines. Fuel cells and batteries are much the same, replace after a certain life, and with built in tolerance to failures. Unfortunately, with fuel cells, as opposed to batteries, we still have some balance of plant that will need maintained, compressors for example, however unlike a turbine engine, they don't operate at high temperatures and are a smaller part of the system, so we can design for much longer lifetimes that you can get away with in a turboprop. All this leads us to estimating 65% saving on engine maintenance. Battery electric companies are going after more like a 90% saving.

fakedang5 hours ago

Are you the guys from Australia who were asking about Aerospace opportunities as an Australian company here on HN some time back?

stuart8ol5 hours ago

No that wouldn't have been us. Hope the feedback they received was "Australian aerospace company - great idea!" though.

c_o_n_v_e_x12 hours ago

What kind of FCs will you be using?

stuart8ol12 hours ago

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.

scythe14 hours ago

I can't help but notice the resemblance to -- do you have any major differentiators in mind, or are you planning to try to beat them head-on?

stuart8ol13 hours ago

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.

aavci14 hours ago

Really cool!