>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

>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) That is the top warbirds' speed at 1/4th power and double range. Basically a top speed for a reasonably powered propeller aircraft. Sounds like we have a winner here. I wonder if chasing hydrogen fuel cell will add a lot of costs and risks in development and various issues for users like it can be expected with a new technology. I'm all for electric, yet i think it may make sense to separate development/products - one is extremely efficient and fast plane with already great aircraft diesel, and another - the same plane (or may be adjusted as needed) with hydrogen.