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Comment by rushingcreek | Hacker News Reader

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.

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

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.

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.

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?

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.

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?

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