[stuart8ol]

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.

[genman]

How is the noise difference between electric and combustion engine?

[stuart8ol]

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.