Supersonic electric propulsion systems for airliners

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Discussion Overview

The discussion revolves around the feasibility and concepts related to supersonic electric propulsion systems for airliners, particularly focusing on vertical takeoff and landing (VTOL) capabilities and potential technologies. Participants explore various propulsion methods, including magnetic hydrodynamics (MHD) and hydrogen fuel cells, while considering the implications of current battery technology and the challenges of achieving supersonic speeds.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants cite statistics suggesting significant reductions in operating costs and emissions when replacing traditional jet fuel with batteries, as reported by Zunum Aero.
  • One participant references historical NASA research on space-based solar power and its potential application for powering aircraft, although this idea is challenged as not directly related to the supersonic electric jet concept.
  • Concerns are raised about the feasibility of achieving supersonic speeds with current propulsion technologies, with some arguing that propellers cannot reach such speeds due to aerodynamic limitations.
  • There is skepticism regarding the practicality of existing battery technology for long-haul flights, with hydrogen fuel cells being suggested as a more promising alternative for electric propulsion.
  • Some participants express doubts about the technical feasibility of supersonic electric jets, suggesting that significant advancements are needed before such designs can be realized.
  • Discussion includes the potential of MHD propulsion, with one participant suggesting it could enable supersonic or hypersonic flight, while others question the applicability of the proposed designs and their representation in visual materials.
  • Participants highlight the need for rigorous analysis and caution against mixing predictions and examples without clear distinctions.

Areas of Agreement / Disagreement

Participants express a range of views on the feasibility of supersonic electric propulsion, with no consensus reached. While some propose innovative concepts, others emphasize the significant technological hurdles that remain, indicating a general uncertainty about the timeline for practical applications.

Contextual Notes

Limitations include the dependence on current battery technology, unresolved questions about the practicality of proposed propulsion methods, and the challenges associated with achieving supersonic speeds. The discussion reflects a mix of speculative ideas and technical challenges without definitive resolutions.

Xforce
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TL;DR
Electric jet liners may sound eco-friendly, however they are small, slow and weak... if power isn’t a major problem, what can we use?
Tesla+SpaceX= supersonic VTOL suborbital electric jet?
“I have an idea for a vertical takeoff and landing supersonic jet.”

Elon Musk, every time the subject of electric planes comes up, to include almost never using the VTOL abbreviation for some reason that’s probably very unimportant.

Statistics:Swapping Jet A (kerosine plane fuel) for a battery can bring a reduction of 60-80% in operating costs, 80% lower emissions and noise, and a 40% reduction in runway needs (not including VTOL), according to numbers crunched by one of the startups in the nascent electric aviation industry, Zunum Aero. Also, around 75% of all flights are domestic, and out of those, around half are under 700 miles and 20% are under 350 miles.
This is a picture of the proposed sub-orbital, supersonic electric jet, looking rather like the MHD Ayaks jet from USSR

14E07303-5054-46D0-81B0-BF577F1572D1.jpeg

How would we achieve supersonic speeds using just electric propulsion? What could the Musk jet be?
Propellers? Certainly not, just like the first generation of planes and common amongst electric planes. This method usually only achieve velocities below 300 knots (154m/s). The fastest turboprop plane was the Tu-95 I think, which the top speed was about the same speed as cruising speed of a turbofan airliner. Still, it’s impossible to reach supersonic speeds with propellers, since long before breaking the sound barrier, air around the propellers already reaches supersonic speeds (which is troublesome)
 
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NASA 30 years ago had a good academic research effort focused on space based solar power, sending the power back to Earth by microwaves or lasers. There was a summary of the main papers published under the rubric of 'Radiant energy conversion in space'.
One extension of this concept was for aircraft powered from space. So electric, albeit in a somewhat roundabout way. If ever the climate change pressures get too much, perhaps these ideas will get resurrected.
 
etudiant said:
NASA 30 years ago had a good academic research effort focused on space based solar power, sending the power back to Earth by microwaves or lasers. There was a summary of the main papers published under the rubric of 'Radiant energy conversion in space'.
One extension of this concept was for aircraft powered from space. So electric, albeit in a somewhat roundabout way. If ever the climate change pressures get too much, perhaps these ideas will get resurrected.
Emm, this idea of supersonic electric jet is from Elon... and I don’t think it involves beaming power from space. Also, I’m trying to ask what kind of propulsion might it use.
 
Xforce said:
Statistics:Swapping Jet A (kerosine plane fuel) for a battery can bring a reduction of 60-80% in operating costs, 80% lower emissions and noise, and a 40% reduction in runway needs (not including VTOL), according to numbers crunched by one of the startups in the nascent electric aviation industry, Zunum Aero...
This is a picture of the proposed sub-orbital, supersonic electric jet, looking rather like the MHD Ayaks jet from USSR
You are mixing and matching different predictions (not statistics) and examples. Please do a better job of being more rigorous and accurate in your analysis/reporting.
 
I
russ_watters said:
You are mixing and matching different predictions (not statistics) and examples. Please do a better job of being more rigorous and accurate in your analysis/reporting.
mean according to that picture, it looks like a MHD. Not meaning that it (a Tesla/SpaceX passenger jet) is a similar thing as that Russian spy plane. And I’m skeptical about that picture as a concept. I just want to show that such concept of a supersonic (actually, hypersonic, as it goes at 4000m/s , around Mach 12) electric jet does exist before, and MHD is a really feasible way.
 
There may be concepts, but they should be at least vaguely feasible.
Current battery technology may allow short hop propeller driven commercial flight. Long haul is still far from any practical stage, hydrogen fuel cells appear to be the most promising power source, supplying electric motor driven fans. Supersonic flight is much more demanding still, because it requires gobs of power, so much that we are not close to a new supersonic transport, fossil fueled or electric, hypersonic steps that up another notch.
So the dreams of electrically powered hypersonic jetliners will remain dreams for at least a couple of decades, too many pieces are missing to make a technically feasible design.
 
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etudiant said:
There may be concepts, but they should be at least vaguely feasible.
Current battery technology may allow short hop propeller driven commercial flight. Long haul is still far from any practical stage, hydrogen fuel cells appear to be the most promising power source, supplying electric motor driven fans. Supersonic flight is much more demanding still, because it requires gobs of power, so much that we are not close to a new supersonic transport, fossil fueled or electric, hypersonic steps that up another notch.
So the dreams of electrically powered hypersonic jetliners will remain dreams for at least a couple of decades, too many pieces are missing to make a technically feasible design.
I want to know the propulsion tech that enables supersonic/hypersonic electric propulsion. Propellers won’t do. I was considering about MHD like stuff
Also flying at high speeds and high altitudes increases the range (less time and less drag) which enables longer ranges, also maybe continuous boost-glide and sub-orbital hops will increase the range even more.
If you’re talking many decades away, probably when things like MHD is mature technology, fusion will also be ready and it enables nearly unlimited range.
This is how MHD works. although the flying craft isn’t a saucer, but if it’s supersonic and it’s VTOL, probably it is.
7AADF622-715B-494B-9A64-A1CA23914CDD.png
 
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MHD in propulsion is an electrically accelerated plasma flow. The concept is closest to implementation afaik
with the VASIMIR rocket thruster, which NASA is funding but which has not yet flown.
Sadly the posted picture is so absurdly simplified it is hard to relate to MHD in any way. Indeed, it seems to represent some purely electromagnetic components, with no discernible propulsion element. Nor any indication why the Laplace forces highlighted would provide such propulsion.
 
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