What about electric planes
========== MotorsElectric motors are very small and light
if allowed to run fast, say 100m/s or more. Only the force costs materials and losses, speed is for free. Look wikipedia
second picture: wikipedia
the HP stage pair is grey, the three parallel LP stage pairs are yellow, the alternator is red. Or check my estimates scienceforums
a ring electric motor of Cu, Fe and optionally Nd-Fe-B as slow as the fan fits in the same volume as the turbofan and is 1/3 as light. A gear would squeeze the motor further.Aeroplanes need no superconducting motors
, simply because the motors are fast. Superconductors are dangerous
: they can quench and explode, and have more failure modes while Cu+Fe motors are extremely reliable. I strongly believe superconducting motors for aircraft are wasted time and moneys.
They are still heavy and demand special aeroplane design. This fits hobby or schooling use. Examples
(Fly 60+30mn) Pipistrel
- (paperwork) scienceforums
Airliners must carry many passengers and if needed divert to an airport 100nm away then wait 45min in the air. Batteries don't fit airliners presently
. Much effort was already invested in batteries, so progress is probably expensive.
========== HydrogenHydrogen provides more energy hence flight time and range
than the same kerosene mass.
Light tanks store liquid hydrogen at atmospheric pressure
. My paperwork: scienceforums
I consider all designs around gaseous hydrogen under pressure inadequate for aircaft. Too heavy, too dangerous. Liquid hydrogen is a smaller explosion hazard Part1
Fuel cells are 60% efficient, commercial hot SOFC were measured at 62% in 2018, with progress at limited cost fuelcellsworks.com
while the best gas turbine, terrestrial hence heavy, 10* as powerful as an airliner engine, converts 43% of the fuel energy into shaft energy ge.com
and gas turbines take two decades and huge investment to gain 6 points efficiency.
I claim that consuming 1.5× as much hydrogen in a hydrogen turbine is nonsense
. Hydrogen tanks are already bulky enough. Hydrogen has a cost. This development squanders moneys. Aircraft will fly with fuel cells.
This is even more true for cars. One company develops a hydrogen engine, despite fuel cells are fully operational for cars.
Fuel cells for the Toyota Mirai weigh 0.5kg/kW wikipedia
This is perfect for rotating-wing aircraft
. Design examples with masses, still 1kg/kW there: masses
Electric motors being cheap and light, four rotors, or six or more
for redundancy, are better than one or two with cyclic pitch.
Light hydrogen brings flight time and range
. Kerosene lets operational copters fly for around 1h, too short for search, rescue and surveillance at sea and moutain, badly short for oil platform service or road rescue. Copters could be first to adopt hydrogen.
Hydrogen improves also light and business aircraft
with present fuel cells scienceforums
- scienceforumsRegional and cargo aircraft
are slower, they need less power and live with present fuel cell performance scienceforums
(1kg/kW) - scienceforums
are faster, they need more power, but 0.5kg/kW plus the hydrogen, the tanks and the motors weigh a much at lift-off as the kerosene and the engines. Hydrogen fits under the wings scienceforums
Only supersonic planes fly badly at M1.3 with fuel cells, still 1kg/kW there scienceforums
So even at 1000km/h, lighter fuel cells are no prerequisite to fly
, they're only a strong wish. The automotive industry improved them enough for cars. Aeronautics can lighten them further. Fuel cells need area while the volume weighs, so improvement must be possible. Planes may have specific demands too. Less effort was invested in light fuel cells than in gas turbines, letting hope progress at limited cost. That is a useful research direction.Aluminium cables
work at high voltage lines. Aeronautics should make them operational in aircraft. Research topic.
And among the transports, aeronautics is the one that needs hydrogen
rather than batteries, boats possibly too.