Jet engine fed out of thin air...
 

China used to build your rubber duckies.
Now the they lead research...
Or do they?

https://inews.co.uk/news/scientists-...-flying-424978

Scientists in China target emissions-free flight with air plasma jet engine

The prototype engine uses compressed air and electricity to create enough power to lift a plane in the air

https://inews-prd-a-images.s3.eu-wes...aled-84x84.jpg
By Madeleine Cuff
May 5, 2020 4:00 pm
Updated May 6, 2020 9:06 amhttps://inews-prd-a-images.s3.eu-wes...-1-640x360.jpgPlanes powered by plasma could usher in a new era of guilt-free flying (Photo: Stuart Franklin/Getty)Scientists have designed a new kind of jet engine that could fly planes halfway around the world without emitting fossil fuels.

The prototype, dreamed up by engineers at Wuhan University in China, relies on thrusters powered by compressed air and electricity to create zero carbon flight.

Green aviation

Flying is one of the fastest-growing sources of greenhouse gas emissions. Researchers have spent years hunting for low-carbon technologies to cut flying’s carbon footprint, but finding a fuel source that is powerful enough to carry a full-sized passenger jet has proved elusive.
“Although electric motors are used in electric cars or small drones to power their motion, they are unpractical to power large aircrafts,” author Dr Jau Tang told i.

Dr Tang and his colleagues believe the answer to low carbon flight lies in something called microwave air plasmas. Their research is published in the journal AIP Advances.

Plasma thrusters

Beyond solid, liquid and gas, plasma is the fourth state of matter. It’s a form of electrically charged gas, which when activated can cause surges of energy.

Plasma jet thrusters have been used before to power NASA probes in outer space, but they were not powerful enough to fuel flight within the earth’s atmosphere.

The team believes it has solved this problem by designing a thruster that creates plasma mid-air, by compressing air into high pressures and using a microwave to charge it. If scaled up, it can create enough thrust to match a commercial jet engine, the scientists claim.

“Unlike fossil fuels, air is free and is clean with no carbon emissions,” Dr Tang said. “Air is present in the atmosphere and there is no need to carry large and heavy fuel tanks as in the conventional airplanes.”
https://i.inews.co.uk/content/upload...jet-engine.jpgThe plasma would be created in the thruster (Photo: JAU TANG AND JUN LI)“Our results demonstrated that such a jet engine based on microwave air plasma can be a potentially viable alternative to the conventional fossil fuel jet engine,” he concluded.
More work is needed to improve the prototype’s efficiency before it can be tried in a full-sized jet, and getting enough electricity to the engine to create plasma could also be a challenge. But if it can work on a large scale, it could usher in an era of guilt-free flying.

Looks good if it didn’t need a nuclear reactor to make enough electricity for it to be viable in anything big enough to be considered a transport.

That's the issue. It may be a more efficient way to USE electricity than motors, power converters, and associated hardware but it's still limited by the specific energy of batteries...

Right now they get to about 250 Wh/Kg on battery packs. Absolute chemical limit for batteries is about 1,000 Wh/Kg (cell level, not pack level) and that's driven by fundamental chemistry and therefore fundamental physics. So don't talk about "breakthroughs" because there won't be any unless you're talking about diluthium crystals and warp drive :rolleyes"

Kerosene has an energy density of about 12,000 Wh/Kg. So best case batteries fall short by over an order of magnitude.

Long term solution for air transport will be low-carbon liquid fuels, basically fuels we manufacture by one means or another by using carbon from the atmosphere (directly or through plant feedstock). Such liquid fuels release the same carbon as jet A but that carbon was previously extracted from the atmosphere, vice being pumped out of deep wells. Green liquid fuels work, and already in very low quantity use by airlines. They just need to scale it up to get costs down. Cost will likely never be as low as petroleum fuels on average, but should be low enough to be economically sustainable.

Spot-on, Rick.

It’s strikingly convenient that their illustration of “RF Power Supply” and “Air Compressor”....require no power source! :p

That, and repealing the Second Law of Thermodynamics. That too would be helpful...

:rolleyes:

Seriously. Neat idea, but not practical, IMO.

You could maybe argue that a ramjet/scramjet could provide the compressed air for this high tech plasma cutter...? Just spitballing.

A potential compromise would be a conventional engine with air driven turbines (big RATs) to supply electrics. The concept would be like ram jet - use conventional to achieve cruise, the air turbines supply power to the plasma engine.

Sounds like a free lunch to me. NSTAAFL.

Seriously? Have you actually thought this through? Did you pass your systems exam?

So many problems with electrification...How do I know the batteries will always be able to hold 100% of their capacity? What about the fact that airplanes get significantly lighter as the burn fuel en-route? What about all the electricity airports would need to charge the batteries? Is every airport going to have its own nuclear reactor?

I want technology to continue to advance, but talk about hurdles...

All that's true but the real problem with batteries is energy density/specific energy... just can't carry enough juice.

Mathematically impossible to fly larger planes on longer routes. Battery-powered airlines will, at best, be limit to short regional hops. That might actually happen, but I'm talking maybe one hour flight time, if that.

And I'd think the secondary problem would be IF you could have adequate battery density, it would seem it'd be better to just use an electric motor to drive a fan, like pretty much every other electric airplane proposal. Using this exotic process to generate a "jet" of air that would still need to turn a fan, seems to add a lot of extra steps that would just waste energy and add weight. Making plasma is not a big deal, you can do it between electrical contacts. Making it on the scale that would actually transfer enough heat to the air and sustaining that would take massive amounts of energy. I would think this is more along the lines of "we found a new/novel way to make plasma", but due to the laws of thermodynamics and physics, it takes a massive amount of energy to create. Otherwise, as said in this thread, they are essentially claiming "free energy".

Plasma is good for spacecraft, because you have to bring your own reaction mass and it can be accelerated to very high velocities . The more energetic that mass is when it parts company with you, the better your delta-v. And 1/2MV^2 says that a little additional velocity goes a long way, and a lot of additional velocity goes a very, very long way. For a given amount of working mass.

But if you have all the free air you can use, yeah it seems like a fan would be a lot simpler.