ZeroAvia had one....

https://www.flyingmag.com/lessons-learn ... -accident/

A PA46-350 modified with an electric motor and hydrogen fuel cell. They were quietly testing until the accident.

What size was the fuel tank and where was it?

Joby just flew 520miles with the fuel cell.

That changes the game a bit. While they old it mention weight of system etc, just going that far seems like an accomplishment.
https://m.youtube.com/watch?v=egR5buArD ... lvbg%3D%3D

Is there an "end to end" efficiency analysis of hydrogen powered vehicles? LOL

This has all the same buzz that the super light jet market had 20 years ago.

Eclipse, D-Jet, Piper Jet, and on and on. Cheap air taxi by jet for everyone. Personal jets for less than a million.

How did that work out?

Now add vertical lift and batteries to the mix.

19 years ago....

https://www.cbsnews.com/news/flying-car ... 6-07-2005/

It's all vaporware until they manufacture and sell the first thousand or so.

Impressive engineering can't change the laws of physics.

There are a lot of failure modes to consider. For instance, can you land in cruise mode? The wheels look inadequate for that, like a shopping cart.

A 250 RPM prop can't be efficient at 200 MPH.

Weighs 4300 lbs empty, 5300 lbs gross.

No battery or motor specs. 200 MPH max, 100 mile range, but probably not both at the same time.

1400 employees, $2B funding, where is the return?

Are these going to cost $25M each?

Pilot qualifications, ratings?

I personally think a hybrid system, electric motors plus turbine generator, will be the winning solution if it can get us to 800 mile range. Battery only is not that useful.

Ultimately, all these VTOL things are rich people's toys. They are too expensive for people outside the top 3% or so.

The first "real" (non test) accident will change things in the eVTOL industry.

In the eVTOL industry, the question is not which companies will survive, but if any will.

Mike C.

Impressive engineering can't change the laws of physics.

There are a lot of failure modes to consider. For instance, can you land in cruise mode? The wheels look inadequate for that, like a shopping cart.

A 250 RPM prop can't be efficient at 200 MPH.

Weighs 4300 lbs empty, 5300 lbs gross.

No battery or motor specs. 200 MPH max, 100 mile range, but probably not both at the same time.

1400 employees, $2B funding, where is the return?

Are these going to cost $25M each?

Pilot qualifications, ratings?

I personally think a hybrid system, electric motors plus turbine generator, will be the winning solution if it can get us to 800 mile range. Battery only is not that useful.

Ultimately, all these VTOL things are rich people's toys. They are too expensive for people outside the top 3% or so.

The first "real" (non test) accident will change things in the eVTOL industry.

In the eVTOL industry, the question is not which companies will survive, but if any will.

Mike C.

Speaking of hybrid:

https://www.avweb.com/aviation-news/job ... 523-miles/

40 kgs of liquid hydrogen. Apparently, the fuel cell is enough to handle cruise, and the batteries deal with the peak demands of takeoff and landing.

Making 40 kgs of liquid hydrogen is non trivial energy and it boils off easily.

Typical cruise speed was 100 knots, altitude was 1000 ft. Took almost 5 hours.

Was the airport closed for this? They circled right over it at 1000 ft, perhaps 100 circles.

Mike C.

Hydrogen fuel has been crowned "green" and that's all that matters

No, it's always been open while they're flight testing when I stop there for avgas.

Same as anyone else flying the pattern repeatedly. It's not a very busy airport.

I go there at least once a month for fuel (E16 has banned leaded fuel) and I have never seen it.

Vince

Depends entirely on how the hydrogen is generated. If its from coal, the end-to-end efficiency and CO2 emissions are terrible. If its from excess solar (in some areas solar power is thrown away because at peak times it exceeds the consumption / grid capacity) then its free in energy.

I can see hydrogen working for large aircraft for a few reasons:

Most large aircraft fly pretty high duty factors, so boil-off is less of a problem.

The low weight of hydrogen makes it attractive for long flights - a much smaller percentage of aircraft weight needs to be fuel.

Well, not entirely, the solar cells and hydrogen generation plant had to be built and maintained and that costs something ecologically.


It causes a waste product of unburned hydrogen. This occurs between fueling and flight, during flight, and then after flight until the tanks are empty. If a plane lands with 25% hydrogen left, the rest will boil off in due course, probably in a matter of a few hours.


The cryogenic storage, handling equipment, fuel cell are all weight to be dealt with, though.

Handling liquid hydrogen is hazardous. It is below 20 K (-423 F).

If it spills, it quickly boils into gas and mixes with oxygen. That can explode, like the Hindenburg.

Mike C.

Yeah, same deal at KRHV.

You'll likely see it during business hours on a weekday.