I was really curious about this as well. Mach 0.8 is less impressive to me than VTOL, but the article didn't provide any details on how VTOL would work.
I know, I was trying to highlight how at the moment (like so many of these "innovative" startups) not much of substance is shown.
The article itself seems to alternate between deecribing something that already exists and the theoretical calculation about something that will (hopefully) be built.
I use a peculiar combination of adblockers: ublock origin, adguard, privacy badger and adblock plus. Some sites show a pop over warning about them. Kill sticker [1] fixes these sites for me.
Using other blockers along uBO leads to worse results than using uBO alone -- and this may be why you have some sites still showing warnings about blockers. I have been warning people against using other content blockers along uBO since a long time now, see <https://twitter.com/gorhill/status/1033706103782170625>.
I watched the video, and only (maybe) saw STOL, not VTOL.
Looks like they use two Dyson style fans for propulsion, which means the fan blades are on the inside of the fuselage, could be very interesting for an urban environment, as there is less risk of hitting something with your blades.
That being said, they mention a gas turbine is necessary for propulsion, so it probably won't be quiet enough for urban envirnoments
I suspect the "V" is still "in theory," because it probably relies on those fans being rotated, and it looks like the ones in the demonstrator are fixed.
Once the rotation happens, a lot more factors come into play, and those problems are not new (see "Osprey").
I think that SCRAMJet engines also use fluid dynamics, in a similar manner.
An issue with both the Osprey and the VTOL F-35 is that they each have two engines involved in VTOL. So, if one engine fails - then the plane becomes unbalanced and probably flips over. (That's why the F-35 has auto-ejection [1])
This technology is interesting because, if you can have one engine involved in VTOL (like the Harrier) but vector the thrust easily, then an engine failure during takeoff or landing can avoid spinning the plane.
>> An issue with both the Osprey and the VTOL F-35 is that they each have two engines involved in VTOL. So, if one engine fails - then the plane becomes unbalanced and probably flips over.
This is not correct for the V22 Osprey. Either engine can power both rotors through the wing driveshaft.
Disclaimer: I worked with the V22 engine control system at one point (AE1107)
The F-35B is a different beast (lift fan plus tilting jet exhaust) than the Osprey (tilt rotor). The tilt-rotor Osprey has shafts that connect the engines so one can power the aircraft if the other fails. This design feature is also present in the V-280 Valor, the replacement for the Blackhawk helicopter.
Not one bit of info in the GP's post is correct. It's like it was intentionally posted. If it wasn't such an old account, I'd suspect some sort of chatbot was behind it.
Where do you get your information about the Osprey, because it is woefully incorrect. Part of the engineering challenge of the Osprey was specifically to overcome loss of engine. There is linkage connecting both props to either engine so if one engine were to fail, both props would still turn. It's one of the talking points about the damn plane. I'd be quite ashamed for posting such non-sense if I were you.
No the F-35B has only one engine just like the A and C versions. The big fan at the back is powered by a driveshaft from the engine, it's not a separate engine.
And like the other commenter said the Osprey can power both props from one engine (I wonder how that performs though, I'd be surprised if it can sustain a fully loaded hover)
From looking at their website [1], it looks to me like they are just using a jet turbine and routing the air through pipes to those ring-shaped outlets.
"The energy required to propel our smallest aircraft at 200 mph for 30 minutes is 100 kWh. This energy can be provided by 26 kg of jet fuel or 600 kg of modern Li-ion batteries."
Is really "26 kg of jet fuel" comparable to "600 kg of modern Li-ion batteries"?
I do wish in those kind of comparison's they would make them equivalent: as in "26kg of jet fuel + XXXkg of turbine" vs "600kg of modern Li-on batteries + XXXkg of electric motor" since for a flying vehicle the all-up weight is the significant number.
According to Wikipedia [1] jet fuel has 43 MJ/kg and lithium ion batteries with silicon nanowire anode have 1.566 MJ/kg. With that you get get 714 kg of batteries for 26 kg of jet fuel. The Tesla Model S 85 kWh battery has 0.57 MW/kg [2] which gives 1961 kg. Looking only at the energy density, the numbers from the article seem quite optimistic for the battery weight, but it is not clear what they actually calculated and I guess their numbers might contain factors accounting for efficiency. Do they account for the difference in weight, of the energy source and energy conversion mechanism, 26 kg vs 600 kg is nothing were I would expect similar performance?
>The Tesla Model S 85 kWh battery has 0.57 MW/kg [2]
Note that your source is from 2015. The Model S battery of today has a higher capacity (100 kWh) and has undergone constant lightweighting improvements.
1 gallon of regular gasoline is 33kWh and a gallon weighs 6lbs. For a 33kWh battery pack comprised of 18650 Samsung 35E cells, you’re probably looking at around 300lbs for just the cells alone.
Irregardless, it doesn’t matter because an electric motor will be far more efficient using the energy stored than a fueled engine (be it gas turbine or ICE). In automobiles for example, 80% of the energy from the gasoline is wasted.
The efficiency of gasoline and Diesel engines is a lot better, over 30% and even over 40% for Diesel. I think the best gasoline engines get close to 40%.
Sure, the best diesel engines get 40-45% and some gasoline engines approach 40%, but that is definitely not the norm. The average is 20% for gasoline (hence my prior figure) and 30% for diesel, which is a far cry from the average electric motor’s efficiency of around 90% in automobiles.
Those are all roughly true numbers but you forgot charge efficiency: energy extracted out of battery / energy input into battery. That's also around 90% (assuming higher voltage charging, not 120v AC which would be closer to 60%). That would put total efficiency of battery electric closer to 80%.
But not necessarily more efficient at thrust.. a turbine is mixing fuel with oxygen from the env to both spin the turbine but also vents the exhaust and gets thrust that way. So it doesn't carry smth like 3/4 of its reaction mass. I know that turbofans duct in most of their flow, so not sure how this nets out on a large-scale device.
Deep in the article it mentions a 15 dB reduction in noise compared to a turboprop at the same thrust.
Unfortunately, though, they don't give hard numbers… If that's 120 dB versus 135 dB it's still too loud for urban environment. But 105 dB versus 120 would make a huge difference and likely be tolerable for a city if it's kept to landing pads on skyscrapers.
Putting landing pads on skyscrapers is mostly a fantasy. There are only a few such pads today. They can't easily be added to existing buildings because the roofs are already used for antennas and climate control machinery. Weight is an issue. And even relatively quiet aircraft are going to annoy tenants on the top floors.
> Putting landing pads on skyscrapers is mostly a fantasy.
Then let me share another fantasy with you: reading what you wrote, there's no need to land on skyscrapers then, drop a stairwell - similar to some private jets and helicopters.
A UAV is still dangerous around people even with no blades involved; a falling UAV is enough to kill. This is a real issue that companies (startups and giants from the domain) are trying to solve, which is required for unmonitored UAV in urban areas to start getting legally accepted (at least in France).
Ballistic parachutes have been around for a long time. I wonder if they can use that with an audible alarm to eeduce the likelihood of a person strike.
Noise reduction is probably the most relevant but I suspect there’s plenty of minor benefits like a smoother airflow reducing turbulence.
I seriously doubt it’s actually worth it, but you might be able to do VTOL without V-22 Osprey style rotating blades or similar compromise. Instead using internal ductwork and redirected airflow.
The thruster component needs only source of high pressure air - the thrust is generated by using this air to generate a low pressure zone that sucks in air from the front of the thruster element.
The turbine that is used to generate the high pressure air has blades so it's bladeless in similar way as the Dyson bladeless fan is bladeless. Not really bladeless, but established use of language allows this.
Dunno, in terms of just the Dyson fan, the bit implementing the main feature of the offering needs just high pressure air so it could be just as well connected to a high pressure air feed. The fact it comes integrated with a turbine that has a blade means there IS a blade included with the product, but it's kind of an implementation detail that could be implemented some other way.
The engineer in me wants to read this "omg they have invented an efficient bladeless turbine" but that's not really what this is about.
Sorry all I can see is comical pair of glasses and a fake nose on a plane!
It’s an interesting idea, but that they’re leaning into VTOL implies the efficiency is less than a conventional jet engine, which is a shame. I’m sure it will have military applications though if they can vtol working.
Well, they have time then. All military VTOL programs (the ones I know of) in the development pipeline are conventional: either helicopters or jet engine powered (I think the only one here is the F-35). Until the follow-up generation to those comes, this type of engine has around 20 to 30 years of development time left.
That being said, this whole idea is too late to the eVTOL start-up craze. Three years ago the animations alone might have been worth 100 million or so.
Are there any batteries in development with a 1500 Whr/kg density? I think I remember one (LiS type?) that is supposed to hit 1000 Whr/kg in the next few years. But that was the highest I heard of so far.
Just as a comparision -- gasoline has a whr/kg density of 12,200. That shows the incredible efficiency of gasoline as a fuel store. This is also part of why it's unlikely we'll get electric powered aviation to replace our currently common uses. The batteries would simply weigh too much, even with incredible advances in the technology.
Liquid hydrogen is a viable alternative, though, as its density is 39,000 Wh/kg.
There are some ultralights that are electric. That's mostly what I would be interested in. It seems those would be a great segment to target, especially if the FAA allows increases the allowable weight limit for an electric ultralight to equal that of a gas ultralight with fuel (extra 30lbs). The electric motors tend to be more reliable than some of the traditional ones (or at least in the state of maintenence that is typical), and you have some weight savings there too (maybe 30lbs). Once you have 1+ kWhr/kg, that starts to look really attractive for that use case... depending on price of course.
Hydrogen would be interesting, but has some drawbacks for that use case - mostly heavy/bulky tanks and the need for heavier 4 stroke engines.
> […] has demonstrated the ability to reach speeds of 0.8 Mach (614 mph) during testing. The figure makes it quicker than a Boeing Dreamliner and twice as fast as tiltrotor designs.
The 787 Dreamliner cruises at mach 0.85 and top speed is mach 0.90. This mistake casts doubt over all other stated facts in the article.
No, the bypass air in a turbofan is still directly driven by the fan, it's only bypassing the turbojet that powers the fan.
This is using the coanda effect to use a little bit of driven air to move a much larger amount of air for thrust. While quieter, it is only efficient at low speed and it takes a physically much larger engine to produce the same max thrust.
80 comments
[ 2.5 ms ] story [ 141 ms ] threadhttps://www.youtube.com/watch?v=xV_AVsscuBk
The article itself seems to alternate between deecribing something that already exists and the theoretical calculation about something that will (hopefully) be built.
Dark Reader gets my second vote on "why is this an extension?"
[1] - https://addons.mozilla.org/en-US/firefox/addon/kill-sticky/
Looks like they use two Dyson style fans for propulsion, which means the fan blades are on the inside of the fuselage, could be very interesting for an urban environment, as there is less risk of hitting something with your blades.
That being said, they mention a gas turbine is necessary for propulsion, so it probably won't be quiet enough for urban envirnoments
I suspect the "V" is still "in theory," because it probably relies on those fans being rotated, and it looks like the ones in the demonstrator are fixed.
Once the rotation happens, a lot more factors come into play, and those problems are not new (see "Osprey").
I think that SCRAMJet engines also use fluid dynamics, in a similar manner.
This technology is interesting because, if you can have one engine involved in VTOL (like the Harrier) but vector the thrust easily, then an engine failure during takeoff or landing can avoid spinning the plane.
[1] https://www.thedrive.com/the-war-zone/the-f-35b-can-eject-it...
This is not correct for the V22 Osprey. Either engine can power both rotors through the wing driveshaft.
Disclaimer: I worked with the V22 engine control system at one point (AE1107)
And like the other commenter said the Osprey can power both props from one engine (I wonder how that performs though, I'd be surprised if it can sustain a fully loaded hover)
[1] https://jetoptera.com/technology/
"The energy required to propel our smallest aircraft at 200 mph for 30 minutes is 100 kWh. This energy can be provided by 26 kg of jet fuel or 600 kg of modern Li-ion batteries."
Is really "26 kg of jet fuel" comparable to "600 kg of modern Li-ion batteries"?
Thanks!
[1] https://en.wikipedia.org/wiki/Energy_density
[2] https://en.wikipedia.org/wiki/Tesla_Model_S#Battery
Note that your source is from 2015. The Model S battery of today has a higher capacity (100 kWh) and has undergone constant lightweighting improvements.
[1] https://www.teslaoracle.com/2022/02/18/model-s-plaid-battery...
Irregardless, it doesn’t matter because an electric motor will be far more efficient using the energy stored than a fueled engine (be it gas turbine or ICE). In automobiles for example, 80% of the energy from the gasoline is wasted.
Unfortunately, though, they don't give hard numbers… If that's 120 dB versus 135 dB it's still too loud for urban environment. But 105 dB versus 120 would make a huge difference and likely be tolerable for a city if it's kept to landing pads on skyscrapers.
Then let me share another fantasy with you: reading what you wrote, there's no need to land on skyscrapers then, drop a stairwell - similar to some private jets and helicopters.
Maybe there's a new way to build compressors I don't know about?
[0] https://en.wikipedia.org/wiki/MDM_MDM-1_Fox
Does this offer any benefits over regular props?
I seriously doubt it’s actually worth it, but you might be able to do VTOL without V-22 Osprey style rotating blades or similar compromise. Instead using internal ductwork and redirected airflow.
Sounds like bunk. You still have this turbine with rotating parts. Unless their big qualification is "outside the airframe." Then, sure. OK.
The turbine that is used to generate the high pressure air has blades so it's bladeless in similar way as the Dyson bladeless fan is bladeless. Not really bladeless, but established use of language allows this.
The engineer in me wants to read this "omg they have invented an efficient bladeless turbine" but that's not really what this is about.
It’s an interesting idea, but that they’re leaning into VTOL implies the efficiency is less than a conventional jet engine, which is a shame. I’m sure it will have military applications though if they can vtol working.
That being said, this whole idea is too late to the eVTOL start-up craze. Three years ago the animations alone might have been worth 100 million or so.
So air is negative, surface beneath the wing negative charge, surface above the wing positive charge, etc.
I'm not sure what the achievable efficiencies are, but I think one downside is that they can generate ozone.
https://en.m.wikipedia.org/wiki/Moller_M400_Skycar
Liquid hydrogen is a viable alternative, though, as its density is 39,000 Wh/kg.
Hydrogen would be interesting, but has some drawbacks for that use case - mostly heavy/bulky tanks and the need for heavier 4 stroke engines.
The 787 Dreamliner cruises at mach 0.85 and top speed is mach 0.90. This mistake casts doubt over all other stated facts in the article.
This is using the coanda effect to use a little bit of driven air to move a much larger amount of air for thrust. While quieter, it is only efficient at low speed and it takes a physically much larger engine to produce the same max thrust.
https://www.darpa.mil/news-events/2023-01-17