Submitted by lughnasadh t3_10iq1ok in Futurology
The following submission statement was provided by /u/lughnasadh:
Submission Statement
Should this technology work as envisaged, I would assume it will be considerably cheaper than existing aircraft designs. As with electric cars, fewer moving parts means easier to build and less need for maintenance.
Though I'm not sure that will make much difference to the economics of flying taxis. There are lots of reasons to question if they will ever make sense, from a business point of view, even with cheaper aircraft.
Please reply to OP's comment here: https://old.reddit.com/r/Futurology/comments/10iq1ok/seattlebased_jetoptera_is_developing_a_vertical/j5fpye4/
This sounds like a great comparable to scram but you still need a shit ton of power to accelerate up Mach 3 before this engine is operational
reminds me of a Dyson fan!
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I will say the leap from this to a flying car is somewhat big.
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If it has the reliability of a Dyson vacuum cleaner, then I’ll take a hard pass.
Don’t normal aeroplanes already cruise at like 900kmh? What’s the big difference ?
This title is super click-baity and almost a blatant lie. If you read the article, its still powered by a regular old gas turbine (aka jet engine, which are far from simple and definitely have moving parts) but the thrust is directed by something similar to what you see on a Dyson fan, instead of a traditional nozzle like most aircraft.
>>Don’t normal aeroplanes already cruise at like 900kmh? What’s the big difference ?
Jet airliners (Boeing, Airbus, etc) are about the same speed, but this engine isn't competing with those.
This design only works on smaller planes. So this is faster than most of those, and it seems quieter, more fuel efficient and cheaper to maintain.
Ah ok got it
Depends how close they are together.
Wouldn't this work well for submarine vehicles also?
If you look for the conference of one of the conceptors, you may understand why it is interesting. An helicopter is presently he Best solution efficiency wise because there is one large rotor. Yet, it is noisy, cumbersome and dangerous (big blades turning fast). So, if we fan get rid of open blades, it s quite interesting for some uses. An helicopter is great in hovering but not adapted for long distance and going fast. So, you want wings. And wings like fast moving air on the upper wing for best lift. If you have standard props, it does not fit well since it is a circular design and the wing is flat. You could make the wing half circles and it works but has drawbacks https://en.m.wikipedia.org/wiki/Channel_wing . Hence, some air taxi makers use lots of small turbines on the upper surface. But If you have a compressor, the design of the exhaust can be anything you like and you can blow the best way on the upper surface ! You can also combine with a "box wing design" . Brillant. The only question of those kind of design is what happens when the compressor fails mind flight. What is the glide possibility ?
> 10% more thrust and uses 50% less fuel
This kind of claim is always a red flag. Why wouldn't they compare it to an engine that uses the same amount of fuel, or one that creates the same amount of power?
Water isn't compressible.
Ah, you're so right, I was just thinking about the "fluid dynamics". Short-sighted..
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The first fucking sentence in that article. Man people are morons.
Obviously it needs a compact, high powered engine. In aviation this means gas turbine.
However, this is absolutely an innovative way of delivering that power. Turboprops are efficient, but require complicated gearboxes. Jets are noisy and inefficient, unless it’s a turbofan, but those are big.
This is like halfway between a jet and a turboprop.
when you have loose power, with box wing design you can still glide, with their other designs you need a parachute.
Helicopters can auto rotate, but they can't pop up a parachute. Russians tried blowing the rotor blades of for a parachute, but it never got anywhere.
But in low speeds and low altitudes, this might be more dangerous than a helicopter
My point was that the title of the post is incredibly misleading. I'm not saying that it's not a good idea or that it won't work. Just that it's not some magical solution.
Why do people keep falling for these impossible technology scams?
Oddly enough, and I’m not talking out of my ass (Licensed aircraft powerplant mechanic) a jet turbine is easier to work on than any reciprocating/piston engine in my opinion. Simplicity is what makes turbine based power plants so reliable. Sure to someone who’s not mechanically inclined it would seem so but it’s actually very simple.
I dunno, coming from military aviation it’s a good title.
Like, clearly it needs a power source, and clearly that’s a gas turbine engine. But putting power down, efficiently, without a gearbox or transmission is revolutionary.
Edit: also for people who are worried about that kind of thing, you can make this green / zero emissions. Solar powered ammonia production is ramping up quickly, and ammonia is an easy substitution for gas turbine engines. Loses about 30% energy density over jet fuel, but it’s workable when range isn’t a limiting factor.
I agree, turbines are simple compared to piston engines. They aren't "almost no moving parts" simple though. My point was that the title of the post was misleading about the power source, as if they'd invented a new type of engine or something, which isn't the case. I am fully aware of how reliable turbines are I was just disappointed once I read the article based on the title.
It's not a good title at all. A gas turbine is not some "new type of engine" and they definitely aren't "bladeless" so I don't know why you think that.
30% less energy dense is a hell of a lot since range is always a limiting factor in aircraft. I don't see that becoming a commonly used fuel in the industry.
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https://aviationh2.com.au/liquid-ammonia-is-the-carbon-free-fuel-of-choice-for-aviation-h2/
If you run the numbers for a typical jet design, carrying 30% more fuel for range is fine for medium range sorties. Anything over ~10h will probably require some kind of biodiesel fuel, but sub-10h in an A330 or long range private jet is very workable.
And as more countries force carbon emitters to pay for their negative externalities via tax, green fuel will become cost competitive. With cheap solar, ammonia should be similar cost to current jet fuel prices, so it'll be significantly cheaper. Western Australia and other places are setting up huge green energy projects for cheap ammonia and hydrogen fuel.
Also, given the increasing protest movement against private jet emissions, people will be willing to pay extra for green fuel. Hell, if I ran PR for an ammonia aircraft startup I would be doing everything I could to encourage protests...
Dyson fans have many moving parts in the base
Most aircraft don't have the space for more fuel tanks to carry 30% more fuel so there's a big issue with that right off the bat. Also that increases the weight of the aircraft, not just from the fuel itself as the airframe will have to be strengthened to carry the extra weight. Weight is by far the most important limiting factor when it comes to range so if youre looking to fly very far at all. Carrying 30% more fuel is a huge issue for most types of aircraft and is not gonna cut it.
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Have you done ATPL flight planning? Most commercial jets operate economically on routes that are much shorter than their max range.
Plenty of 787s are doing NY-LAX.
I believe this is what u/slowslownotbad was referring to in their previous comment when they spoke on the 30% efficiency decrease
Ha, he said windbag
>They aren't "almost no moving parts" simple though
The people who say this conveniently omit the myriad of valves and pumps and switches and mechanical computers (or computer computers) and bearings and fluids and reservoirs that are required to safely feed fuel to the engine, manage its airflow/temperature/RPM/acceleration/pressures, and lubricate it.
I’m still waiting for the vacuum cleaner-powered hover craft from the 1980s to work.
I've played around on one that was powered by a snowmobile motor.
Because it is!
You have an internal fan that pushes the wind up into the ring that blows it out the sides and forms a “tunnel” of low pressure that pulls air long with it. There is a link in the article to the inventor of dyson fan who explains it.
Not the same mechanism, but the Magnetohydrodynamic drive is an interesting "no moving parts" design which functions in water (and other fluids), albeit inefficiently.
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How small are we talking here? Also, can that thing glide?
Take my money. You beat me to it.
I’m curious as to the sound of it, and wondering if the sound can be dampened down to a point of 80 db?
Bernoulli's Principle!
I always loved science teacher jokes.
Isn't that also because the pilots have to have surplus fuel for their alternate landings as well as possible holding patterns due to emergencies or priority changes?
Most things can glide given the right conditions. 😁
More seriously, I'm no aviation guy but gliders tend to have longer wings and are light particularly because of their lack of engines. So while traditional planes can glide some, the compactness of this design makes me think it would be especially poor at gliding.
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I'll believe it when it actually flies. So many new-fangled aerospace projects get cancelled after the companies behind them realize that they're actually super hard to do
so does this thing. I looked at the diagram.. it's a jet turbine in the middle with ducted air.
Yeah the glide range of this thing would be abysmal, and the speed with which it would achieve best glide distance would probably make an emergency landing/ crash far less survivable. Perhaps it’ll come with a parachute system?
Traditional planes can glide some and hit the ground at a more gentle angle and do I recall that helicopters do some slow rotator spin to make landings more survivable?
That was something that came to mind, if these are an improvement on helicopters that'd be great, but if they became known as deathtraps when the engine fails it could tank the tech forthwith.
Conventional turbofan engines don't have a gearbox or transmission. The closest thing they get is that they might have two or at most three shafts for their turbine/compressor stages.
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Also the hundreds or thousands of turbine and compressor blades
You're assuming that aircraft are already filled up to max, and thus would need extra tanks and being reinforced to hold them, etc.
That's just a wrong assumption though.
Take most any flight within Europe, or even coast to coast US like JFK to LAX as u/slowslownotbad mentioned. These flights run a couple hours, 5 tops, right?
Now let's look at an aircraft like the 737-800. It burns ~5,000 lb of fuel per hour, with a max capacity of 46,000+ lb. A 5hr flight would burn 25,000 lb of fuel. You take enough fuel onboard to get to the destination, plus an extra amount in reserve (startup, taxiing, weather diversions, holding pattern at destination), and then enough beyond that to get to an alternate airport if you can't make the planned destination.
For the sake of argument, let's say that added up to 30,000 lb. That still leaves 16,000 lb empty on the longest continental flight. That right there is beyond the 30% increase we are talking, so it's not crazy to think that airlines could switch over to a greener fuel on flights under certain distances. They'd have the capacity.
I was wondering about emergency landings, not gliding as plan A
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>and do I recall that helicopters do some slow rotator spin to make landings more survivable?
Aurorotation. The airflow through the rotor reverses and the spinning creates a ton of drag.
Yeah the more wing you have the better you can glide- more or less. An airliner can glide a LOT better than an f-16. Helicopters can do what’s called an auto-rotation, the airflow over the blades creates lift and spins them- same principle as a gyrocopter- thus slowing descent. A parachute would be the only way this thing makes sense. I imagine it would be installed considering they’re not hard at all to put on a composite frame aircraft
That's true. The main advantage of this over a turbofan is size - efficient turbofans are quite large.
To be fair, small turbofans do exist, but they're not very efficient. For instance, a cruise missile engine might do 0.683 lb/lbf/h (https://en.wikipedia.org/wiki/Williams_F107).
Whereas Jetoptera claims as low as 0.26 lb/lbf/h (https://jetoptera.com/products/). FYI smaller is better, so Jetoptera is claiming better than 2x efficiency when compared to a small turbofan.
Autorotation. If you really want a better understanding of what is happening, read up on autogyros. They are essentially a helicopter in auto-rotation that is pushed around with a propeller.
I'm not arguing the rationale that there are plenty of routes where this is possible. What I'm saying is that there is a huge penalty in the max range of the aircraft, and that makes them much less versatile, limits their route options, and are much less attractive to airlines. You're much more likely to see alternative fuels such as compressed hydrogen used (Rolls-Royce has already run an engine on hydrogen) than you are to see something used that would result in such a huge range penalty.
Could this same concept be applied to a hovercraft?
But even if airlines were to transition over just their short haul flights, that would make a huge difference in terms of fuel/emission savings. It doesn't have to be all or nothing.
When I worked in ATC I learned that airlines (here in Canada, at least) drafted up 3 flight plan proposals for each flight. One was the shortest time, one was the most fuel efficient routing, and one was the cheapest (considering fuel and ATC charges for how many sectors you cross, etc).
I'm sure it wouldn't be hard to factor in alternative fuels when making those calculations.
To add to my previous comment, taking the 787 Dreamliner that someone else had mentioned, you're talking a max capacity of 223,000 lb, and maybe 10,000 lb an hour. Flying JFK to LAX is a joke with that capacity. Definitely room for a less dense fuel in those tanks.
Not a pilot, but yes they do take extra fuel. I believe it's like 5% of the trip total as extra for taxiing and weather reroutes, plus enough to get to an alternate airport if your destination is not viable. Plus aircraft carry an emergency reserve of 30 minutes worth of flight time. If you break into that last bit, you're likely declaring an emergency and ATC will give you priority sequencing to land.
You want to have enough for safety and wiggle room, but not just full to the brim as that's a lot of extra weight to carry around, which means you burn through fuel faster.
Define work. You can ride a very noisy hovercraft operating on what, basically ground effect and a cute skirt quite well... just... maybe not all the way across the pond? You'd need a pretty long extension cord.
Well, perhaps a hovercraft full of eels.
Hmmm I remember seeing a scam company with this idea a while back... pretty sure this is some form of fraud once again.
Pretty sure Luke Skywalker use to rock one of these
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Yeah, alternate fuel stuff seems complicated but it's basically a scenario-based planning exercise. Like, I'm gonna do a long overwater flight to a remote destination, so I need gas for depressurization or single engine failure or weather holding/divert. I'm legally required to carry gas for certain things at certain times, and I can add extra if I want to. But I need to plan to arrive at a low enough fuel state that I can land below maximum landing weight.
That last point is gonna be most limiting for ammonia fuel in certain missions; because NH3 is less energy dense, it will require pilots to routinely land with a greater fuel load of unburned contingency gas. This will cut into usable payload.
So it's not a perfect solution, but it's got tonnes of promise.
In a cosmic sense they're basically simultaneous.
I’ll be thrilled if those numbers come to fruition on a working prototype of actual scale. Until then I don’t want to hear about it.
Vortexes? It’s vortices. But then a comment will come in with “ackshully…”
I'm not a Dyson fan.
Yeah, it sounds like the plane will pop a CO2 cartridge every time it needs thrust.
This is the first time I've seen a genuinely groundbreaking (and real) thing posted here
It mentioned an engine. Engines need fuel. Is that your point???
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I read about this jet before and I remember the inventors saying it will be converted in the future to green power when better technology makes more sense for this jet. Or something like that.
The entire thing is pointless. Their revolutionary propulsion system is no different than a blowgun connected to an air compressor. The only useful application would be for rc planes.
It's all horseshit. It's like those Kickstarters that pop up from no named people claiming to revolutionize the world. Then they raise millions of dollars and disappear into the night. This isn't new technology and it won't revolutionize air travel.
>So while traditional planes can glide some,
Glide ratio of a typical airliner is around 17-20:1 (17 miles horizontal for every 1 mile vertical). Highly maneuverable aircraft are where you tend to see abysmal glide ratios. I don't believe it's publicized anywhere, but I suspect your typical F-35 glides about as well as a brick.
This can take off like a helicopter: VTOL. So imagine a medivac chopper that can then cruise at the speed of an airliner. You could fly direct from the front lines of a military conflict to a field hospital. In other words, you could get to a hospital 3x faster or 3x further in the same time.
The compressor though will certainly have some inertia won't it? Not quite auto-rotation levels of power but, maybe enough for the chute to deploy.
>but the thrust is directed by something similar to what you see on a Dyson fan
Minor correction since we're trying to correct misleading headlines: the thrust isn't from the gas turbine, the air passing through the turbine is simply exhausted. The thrust is from a cold air compressor driven by the turbine shaft. So it's like a turbine powered helicopter or turboprop aircraft in that the turbine is used just like a piston engine purely for mechanical energy.
That's one of the features that the creators are advertising: the thrust is cold and relatively safe, like rotor wash vs standing behind a jet.
Also theoretically with breakthroughs in battery technology, you could skip the turbine entirely. The technology itself isn't reliant on turbines. They could use any power plant: piston, electric motor, Mr Fusion-- anything that can power a compressor.
> they definitely aren't "bladeless" so I don't know why you think that.
It's "bladeless" in that if you're a life-flight medic you don't have to worry about a blade lopping half your head off.
If you took the propeller off of turboprop aircraft it would be extremely safe, even arguably "bladeless" even though the turbine has blades inside of it.
It's a bad headline, but it's closer to the truth than I think you're giving it credit for.
>That's true. The main advantage of this over a turbofan is size - efficient turbofans are quite large.
The main advantage of this over a turbofan is that it can be rotated to offer VTOL or STOVL options.
Pretty easy to rotate a relatively low velocity duct vs rotating an entire turbofan or creating a complex orbital gear to deliver the turbine power to the fans. (See: complicated clutch issues with the F35 VTOL.)
Their first RC plane scale prototype was on a glider.
It's just an alternative to turboprops or turbofans, so sure you could attach it to anything. You could attach a turbofan to a "glider".
>f they go on to prove their worth and make it into production, fluidic propulsion systems will lead to some of the most futuristic-looking aircraft ever built
This is the closest thing to a "Blade Runner flying car" that I've ever seen.
Make them so they can run on hydrogen. Then make them so that people can afford them. Like what Henry Ford did with the Model T.
But we'll call it the Model H
Or depending on the size of the craft a battery.
That’s what you get fo axin.
good point, but if you are below certain altitude chute wont help at all.
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The difference here is how the thrust is delivered. Instead of having the engine directly attached to the propulsion mechanism in the same nacelle (as we see in airliners with turbo fans and turbo props) the propulsion mechanisms can be attached via simple ducted vents. The thrust is also generated from cold ducted air unlike the heated exhaust of most turbojets. Unlike turboprops there are also no external blades to pose a moving hazard. This system should also allow for much quieter aircraft as the gas turbine could be placed inside the airframe and soundproofed much more easily than an externally mounted engine.
The lack of centrifugal force or mechanical drive mechanism in the thrust generators also allows them to be easily rotated without the usual mechanical issues in more traditional designs, making this especially useful for VTOL. The rotation can also allow for the thrust to be used for lift as well as a forward driving force, eliminating the need for lengthy wings. Use cases with multiple gas turbines used for additional thrust should also eliminate problems of a thrust imbalance if a gas turbine failed. The ducted high pressure air should be able to be sent to all thrust generators from any and all gas turbines.
Look up all the difficulties the Osprey has thanks to the complexity of it’s rotating turboprops. This system eliminates all those complexity issues and can provide the exact same functionality more efficiently.
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lughnasadh OP t1_j5fpye4 wrote
Submission Statement
Should this technology work as envisaged, I would assume it will be considerably cheaper than existing aircraft designs. As with electric cars, fewer moving parts means easier to build and less need for maintenance.
Though I'm not sure that will make much difference to the economics of flying taxis. There are lots of reasons to question if they will ever make sense, from a business point of view, even with cheaper aircraft.