There's definitely more to be had in ICEs especially combined with hybrid transmission systems however the perpetual issue is that even expensive fuel is very cheap compared to the capital cost of trying to save it. Currently ICEs are being asked to span too large an envelope to be really as efficient as they could be. Also the current trend in highly boosted engines is less Otto cycle and more combined cycle where multi-stage compressio and expansion is used to improve overall cycle efficiency in the same manner as gas turbines do.

Electric and hybrid-electric aircraft are not really about being green as much as they are about opening up new design opportunities, particularly in the VTOL space. This comes largely from the ability to precisely control motor power electronically as well as the chance to have high power density motors in aerodynamically convenient places. This is new territory though and no one really knows what an optimal configuration actually looks like yet so you're going to see some weird contraptions proposed until we learn enough to know where the advantages lie. All of the electric motor technology is already highly developed and more-or-less on the shelf waiting to be adopted

As far as batteries go, sure there are likely gains to be had out there in the future but useful things can be done with current technology as Tesla has demonstrated in the automotive sector. Whether you like the results or not is irrelevant. The product is as compelling as a phat S-class Benz ever was and as justifiable. Forget the green tripe and look at it purely as a luxury car buying option.

Like any design problem there is no one solution and its all about pushing the compromises around until you get something that works well (or not). Over time designs will converge on perhaps one or two configurations and the real effort becomes fine-tuning the details

...says he who bent his unducted non-VTOL contraption trying to get it on the ground

Jesus might help you in your hour of need though, Sunny...

Folks,
An interesting thought --- a version powered by a battery+a motor/generator hydrogen powered, with the hydrogen source based on the recent UNSW patents for converting liquid ammonia back to hydrogen.
Never say never.
Tootle pip!!

...and the hydrogen could be carried in a giant balloon, which will help keep it in the sky when the batteries fail...

Folks,
What "A Charlie".
The whole thrust of the ammonia/hydrogen development recently patented is an efficient method of producing hydrogen from ammonia (which was produced from hydrogen in the first place)--- or, put another way, using this practical conversion method means the "fuel" is ammonia handled as a liquid.
And as for those of you who have all the answers of why "it" won't work, are you aware that acknowledged technological failures like Mercedes and BMW already (and have for some time) produce their vehicles adapted to hydrogen --- and the delivery points for hydrogen in Germany are multiplying rapidly.
But--- the UNSW patent gets around all the problems of handling liquid hydrogen, and you have a reasonably harmless liquid at normal temperatures fuel --- ammonia.
And, I suppose you all understand that Australia is set to become a big exporter of liquid hydrogen. Or the Japanese and Korean are really dumb signing such big forward supply contracts for hydrogen.
Tootle pip!!

PS: A Charlie, do you have to work at your posts, or does it all come naturally??

DeadSled: There is such a thing called humour, though you appear to lack that gene. Toodle-oo! Pip! Pip!

Yeh come on leaddie enough of the hydrogen balloons already. They went up in smoke years ago. :}

In addition to it not being harmless as pointed out by Sunfish, neither is it liquid at normal temperatures, unless you consider -33 to be normal. That's a lot of fiction packed into a very few words. I admire your efficiency.

Well, it is toxic, corrosive, and flammable. Other than that it's pretty benign.

https://h2.live/en

https://www.tuev-sued.de/company/pre...ldwide-in-2017

German fuel stations for Hydrogen. Thanks I learnt something. As well as being entertained.

Still not as impressive as the CEPS fuel pipeline...

https://en.wikipedia.org/wiki/Centra...ipeline_System

It's all good & well pointing us all in the direction of a future that's possible but we all do live in Australia, a land of inept leaders Inc our aviation authority & corruption that takes us nowhere other than dreams & wishes & I haven't yet met a dream or a wish that gets me off the ground!:-) Dream n Australia, we will only ever follow not lead!

Quite so, but by the same standards petrol is not entirely benign, either, nor LPG (also stored under pressure)
For all the knockers, why not spend a few minutes looking at the U.of NSW public data on the subject, particularly the process for turning the ammonia (in whatever liquid form it might be) back to usable hydrogen and completely non-noxious "other".
Then use your imagination to see how existing distribution and delivery systems could be adapted, rather than dealing with compressed hydrogen, a la Germany, no more difficult than LPG.
Unless, of course, you firmly believe the U.of NSW published data/press releases/industrial scale pilot plant is just "fake news" --- as seems to be the case with more than one of you, not limited to Bloggsie.
Tootle pip!!

Machtuk,
Sadly, a bit too close to the truth.
For those of you who are able, cast your minds back to late 1960s, with the intention of converting the greater part of the Australian vehicle fleet to LPG, and greatly reducing our reliance on imported fuel ( which was less, percentage-wise, than now!!) --- then stupid changes to excise tax policy cut the feet out from under the economics of local LPG, for other than fleet use ---- (and remember it was Labor, whose Shorten tax and spend policies after May will make Whitlam look like a beginner) , so we are now more dependent than ever on imported fuels.
Read Donald Horne's "The Lucky Country".
Tootle pip!!

Folks,
For those of you who are Google challenged, a few hopefully helpful references:
https://www.sciencemag.org/news/2018...without-carbon
https://www.evolving-science.com/env...le-fuels-00729
https://marketbusinessnews.com/austr...s-fuel/182909/
And all of the above without consideration of the recent development to "easily" turn ammonia back into hydrogen and nitrogen.
And that is just the Australian scene.
Tootle pip!!