VTOL On Demand Mobility

Does the weight fraction for the fold system scale up well? I wonder if a UH-60 size platform would be viable. While it might be sensible for the civil market, all of the extra requirements for military use might make this a difficult proposition. It certainly does look promising.
 
So how will this model scale to a crewed airplane? The only issue I see is depending on 4 motors, will this fly ok if you lose one engine?
 
DWG said:
US court denies Wisk’s request for injunction against Archer https://www.flightglobal.com/busine...-for-injunction-against-archer/144740.article

“In essence, Wisk has not shown a likelihood of success on the merits that defendant Archer Aviation Inc. has misappropriated its particular asserted trade secrets,” the court said in a one-page ruling on 22 July.

“There are some arguable indications of misappropriation but, even if the totality of that evidence raises ‘serious questions going to the merits,’ it is too uncertain and equivocal to support a finding of irreparable injury based on misappropriation or that the balance of hardships sharply favours Wisk,”
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It's always fun to watch fancy fledgling aerospace startups fight the laws of (wo)men rather than the laws of physics - this is almost one of those moments where I wish I liked popcorn :D...
 
martinbayer said:
It's always fun to watch fancy fledgling aerospace startups fight the laws of (wo)men rather than the laws of physics - this is almost one of those moments where I wish I liked popcorn :D...
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Not quite facetiously, I'd suggest that they're subject to the laws of evolution instead. We're seeing an explosion of morphologies not seen since the Cambrian.

https://en.wikipedia.org/wiki/Cambrian_explosion
Most will be dead ends, but the vagaries of circumstance make it impossible to predict which will prosper. The self-described 'lapsed marine biologist' Peter Watts has described Darwinian selection as 'survival of the least inadequate'. I might amend that to say it's survival of the cheapest without obvious crippling flaws. In English, that means that the eventually favoured morphology may not be optimum under any single criterion, but adequate in all necessary aspects and economical to build with good capital and an effective distribution network behind it. In plain English, 'who the f*ck knows, but I suppose we can make some informed guesses'.

I was editing a paper on industrial history a while back and the author traced the use of new lighting technologies from industrial to popular domestic uses. First, fluorescent and later LED lighting found its major market in industrial uses - factories and so on - and then after developments in economies of scale and user-friendliness (e.g., the perceived 'cold' colour temperature was a hurdle to early consumers), then it spread to other markets. I suspect that while rich early adopters might want their toys, to provide an economically viable launching pad, one or more of these ventures will need to establish itself in a peculiar but lucrative niche and then spread to others. Which, I don't know, but maybe it is drug smuggling :) That does seem to be a cauldron of innovation, as WH Sutton points out on his blog, Covert Shores, where 'narcosubs' regularly feature.

As I like to say, reality is the best simulator.

So yeah, popcorn.
 
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I can definitely see the parallels here. Aska and Kelekona in particular need to take notes on that cartel drone design if they're serious about not going extinct! :p
 
I am reminded of the problems encountered by the first automobiles and the transition from horse to horseless transport which took several decades to evolve.
But the roads remained more or less the same and the vehicle still ran on wheels. The change was only to speed and propulsion.
Today we have an elaborate layout of roads for ground vehicles and sky lanes of various kinds for air vehicles.
There is no obvious advantage in merging the two. Both are pretty crowded already.
The uses being proposed are similar to the early automobile. Either as a luxury transport for the wealthy or a taxi for a wider but still affluent public.
But both roles can already be met by the helicopter. It is a proven and reliable vehicle which can get from A to B quickly and safely.
It can take off and land in a wide range of places with little preparation. A conventional automobile can connect seamlessly with it.
The role of the air car is more akin to the amphi car or the turbine powered yacht. It is a recreational toy for the Bezos and Musks or even Gareth Southgate.
Rather like a blinged Range Rover this is where these vehicles will be bought. And of course in the playgrounds of the Gulf and China.
 
uk 75 said:
...
But both roles can already be met by the helicopter. It is a proven and reliable vehicle which can get from A to B quickly and safely.
It can take off and land in a wide range of places with little preparation. A conventional automobile can connect seamlessly with it.
The role of the air car is more akin to the amphi car or the turbine powered yacht. It is a recreational toy for the Bezos and Musks or even Gareth Southgate.
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The promis is that eVTOL are less expensive to produce, operate and maintain in contrast to a helicopter... We will see.
 
yasotay said:
Does the weight fraction for the fold system scale up well? I wonder if a UH-60 size platform would be viable. While it might be sensible for the civil market, all of the extra requirements for military use might make this a difficult proposition. It certainly does look promising.
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At small scales it's not hard to build something strong enough, but as you mentioned, make this big enough to be manned, and the fold structure and mechanism become a challenge (to put it mildly).
Consider that ALL the wing loads have to pass through those relatively small hinges. So, roughly speaking, if you were to scale this up to a 7,000 lbs 5-pax eVTOL (Joby or Alia class), and you were sizing for 4.5g's ultimate load factor, those hinges would have to transfer 31,500 lbs of force.
I don't have much practical experience in this field, but if variable-geometry pivot design is any indication, these flight-critical structures are built like tanks.
Actuation is also a challenge. If you notice, for the subscale vehicle they wisely went with a somewhat crude and draggy (but light and effective!) scheme with jointed arms projecting outside of the airframe. I doubt they'd do that for a UAM vehicle.
That being said, for a group I, II, or III UAS, this is probably not a problem.
 
alberchico said:
Very impressive noise profile. However, the Joby prototype is currently flying unmanned, so without any payload the engines might not be operating at full power. Also the AW109 is a much larger heavier machine that can carry 8 people, so it's not the best comparison.
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Get a optical stealth kit and every spec ops team will be getting one? It is not that expensive and a combustion engine can be used when outside of insertion point for militarily relevant performance.
 
Tetra-aviation 33 engines monster:

https://www.designboom.com/technology/mk5-tetra-aviation-personal-evtol-08-02-2021/
I am not sure it is an inherently safe design (large span wing flapping with highly loaded rotors slung under it and M6 screws holding the props for example). Nice to see however yet a new team but focused on adapting existing tech without claiming the wheel was waiting for them to shape it more square...
 
TomcatViP said:
Tetra-aviation 33 engines monster:

https://www.designboom.com/technology/mk5-tetra-aviation-personal-evtol-08-02-2021/
I am not sure it is an inherently safe design (large span wing flapping with highly loaded rotors slung under it and M6 screws holding the props for example). Nice to see however yet a new team but focused on adapting existing tech without claiming the wheel was waiting for them to shape it more square...
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Still not as good as the Narco VTOL Drone.
 
dannydale said:
I can definitely see the parallels here. Aska and Kelekona in particular need to take notes on that cartel drone design if they're serious about not going extinct! :p
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Well, I'd say you're working to a completely different set of requirements depending on whether you want to attract investors/press or whether you actually have to deliver a payload.
 
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GTX said:
TomcatViP said:
Another project based on tilting prop but with a weirdly impossible setup:
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What aspect is "weirdly impossible"? It seems like a quite attractive design to me.
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I guess the small propellers pushing the air straight on top of the wings, when in VTOL mode, might not make for a very efficient configuration.
The hybrid propulsion system, on the other hand though...
 
CiTrus90 said:
GTX said:
TomcatViP said:
Another project based on tilting prop but with a weirdly impossible setup:
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What aspect is "weirdly impossible"? It seems like a quite attractive design to me.
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I guess the small propellers pushing the air straight on top of the wings, when in VTOL mode, might not make for a very efficient configuration.
The hybrid propulsion system, on the other hand though...
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I would also add that it is not immediately clear how they plan to control pitch in hover. Previous tilt-wings have used a small pitch rotor in the back...It is theoretically possible to use cyclic on the wing rotors, but no one has pulled that off yet.
 
Building on CiTrus90 comments:-
Wing bourn flight transition hasn’t been considered/understood;- most of the upper wing surface is in heavy down draft from the props, so it won’t generate lift until it isn’t. When going from wing bourn flight to prop lift, the incidence is the wrong way for lift generation, so will lead to rapid wing stall/pitch change, at a time when the prop lift vector is tiny. The normal way to manage these effects is to keep the downdraft as far forward or outboard as possible.

The graveyard of vtol concepts has been a safe transition.

Sadly lacking in hover redundancy to boot;- the wing blocking airflow of prop will nail any hope of auto rotation.

To me, it’s yet another scheme drawn by a graphic artist.
 
AeroFranz said:
yasotay said:
Does the weight fraction for the fold system scale up well? I wonder if a UH-60 size platform would be viable. While it might be sensible for the civil market, all of the extra requirements for military use might make this a difficult proposition. It certainly does look promising.
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At small scales it's not hard to build something strong enough, but as you mentioned, make this big enough to be manned, and the fold structure and mechanism become a challenge (to put it mildly).
Consider that ALL the wing loads have to pass through those relatively small hinges. So, roughly speaking, if you were to scale this up to a 7,000 lbs 5-pax eVTOL (Joby or Alia class), and you were sizing for 4.5g's ultimate load factor, those hinges would have to transfer 31,500 lbs of force.
I don't have much practical experience in this field, but if variable-geometry pivot design is any indication, these flight-critical structures are built like tanks.
Actuation is also a challenge. If you notice, for the subscale vehicle they wisely went with a somewhat crude and draggy (but light and effective!) scheme with jointed arms projecting outside of the airframe. I doubt they'd do that for a UAM vehicle.
That being said, for a group I, II, or III UAS, this is probably not a problem.
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In addition to the above...
Transwing has batteries installed in the outer nacelles. Therefore the CG moves rearwards as soon as the wings fold and as a result the center of thrust matches with the CG in hover. That works well (as we can see) for applications with a fixed payload installation (UAS).
That said, it becomes a headache if the payload is not a fixed part of the aircraft (e.g. passengers).
 

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It will allegedly fly almost 300 miles on a single charge and fit in a single garage space... a ballistic parachute for "last-ditch safety", and a ballistic rocket system on the bottom of the flying car that would be "similar to what Bezos used to slow down his capsule right before it touched the ground"... a landing solution called "Cat's Paws," an inflatable landing system that would allow the aircraft to perform soft landings, and would even be able to keep it level even if it landed on a slope.

It also has a jacuzzi and makes great coffee.

vertical propulsion systems specialist

So not an engineer then? Novel and vague job descriptions should always set off alarm bells. Like 'architectural designer' means 'not actually a qualified and registered architect'.

As per usual:

...and the company is looking for investment to allow it to move to the following stage of developing full-scale prototypes.

Just a minute while I look down the back of my sofa. If they don't get any money, they can just scale it down to about six inches and market it as a bottle opener.

Mazda Furai concept car mentioned as a previous project by the stylist. I was not a production car - it never underwent serious development - in fact it caught fire and burned to the ground.

9080113.013.Mini12L2.jpg
 
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Indeed.
People posting on SPF this kind of marketing hype could use a modicum of salt, and maybe refrain from reproducing here the most obvious BS. Or choose the Theoretical and Fake area in the Speculation section.

There is also a "blacklist" thread somewhere, and the most obvious scams could go there.
 
https://evtol.com/news/joby-displays-electric-air-taxi-new-york-stock-exchange/
I woke up this morning and saw in the news that Joby brought their prototype to Wall Street and decided to swing by and take some photos. As far as I know this is the first time this aircraft has been on display to the public. I got to say, it is an impressive machine. It's also a bit larger than I expected. People passing by were in shock when they first laid eyes on this thing. Even in brutal 39 C temperatures people crowded around to take pictures of it. I thought I'd upload some of them here. When looking at this machine up close, I felt the same sense of awe that people in the 1950's must have felt when they saw the DH Comet or Boeing 707 for the first time.
 

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“In a normal aircraft, it makes sense to have this quite complex and heavy mechanism on your propeller in order to operate optimally over the whole range,” said Norcia. “Electric propulsion provides some opportunities to just massively simplify the aircraft. So all four of the propellers are fixed-pitch: the ones in front are pitched for takeoff and climb out, and the rear ones are for cruising.”

With a heavy, complex, expensive traditional engine, it would be silly to double the number just so you don’t have to use variable pitch propellers for takeoff. But with light, simple, inexpensive electric engines, it makes perfect sense to do so, even if it looks unusual.

The front and rear propellers are only both active during take-off and climbing, with the front ones folding away afterwards as then the rear ones take over completely for cruise. It mechanically simplifies things — no heavy duty hinges and hydraulics — and in fact putting the prop back there seems to improve efficiency by about 10%, said Norcia. “It’s pretty cool,” he added. (And they’ve applied for a patent.)
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Sourced From the link above.
With 9 pax or less they will reach certification through CS23 that is less stringent than CS25 (large airliner).
The wing span appears however quite large with an inherent wing loading really low to offer a comfortable ride to commuting passengers (in contrary to gliders or light airplane, the business model, as suggested, would involve a lot of flying in non-cooperative weather).
 
The Transwing configuration is elegantly simple compared to many other VTOL approaches. On the question of the high loads on the wing pivot hinges and mechanism, that is certainly a challenge but not one I think is that is technically challenging to overcome in my opinion. The partly external actuation would not be a deal breaker except in the most high-speed applications. Engine-out failure in VTOL and transition modes could be handled by using more engines and props (their site shows a six-engine variant) or perhaps a ballistic recovery parachute and whole-aircraft airbag. Engine out in cruise would be typical of any multi-engine aircraft but the reserve power inherent in a VTOL design would make easier to compensate for the loss of an engine. The CG shift between cruise and VTOL modes seems more of an advantage than a disadvantage by obviating the need for a separate tail prop/duct/etc. to provide effective pitch authority in hover and any imbalance in the CG from varying loads can be accommodated by a forward or rear power bias in VTOL mode. Overall, I agree with Moose that it's a very promising solution to the challenge of VTOL.

https://www.pterodynamics.com/transwing
Moose said:
I like this novel configuration, one to watch.
View: https://youtu.be/3uNboCgDOKQ
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https://www.flyingmag.com/story/aircraft/technicalities-electric-air-taxis/
This article from a respected aviation magazine summarizes the issues with electric aircraft. Depressing reading, but it raises the same points that have been talked about on this forum for some time. And this article doesn't even go into the challenges of getting these machines certified and setting up all the specialized infrastructure that they will need.
 
alberchico said:
https://www.flyingmag.com/story/aircraft/technicalities-electric-air-taxis/
This article from a respected aviation magazine summarizes the issues with electric aircraft. Depressing reading, but it raises the same points that have been talked about on this forum for some time. And this article doesn't even go into the challenges of getting these machines certified and setting up all the specialized infrastructure that they will need.
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I see it as a continuum. Right now a series hybrid with an internal combustion or gas turbine engine adequate for sustained cruise plus a little more for charging the batteries used to give a brief boost for takeoff and hover is absolutely possible. As technology evolves and battery efficiency improves the internal combustion or gas turbine engine will be eliminated.
 
alberchico said:
And yet another short haul electric project materializes. I'm not an aircraft engineer but those engines seem ridiculously small for an aircraft of that size.

https://techcrunch.com/2021/08/12/pyka-shows-off-its-new-electric-passenger-plane-the-p3/amp/
https://flypyka.com/p3.html
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I reckon this as one of the more reasonable proposals although with the usual caveats;- it’s wing aspect ratio gives good cruise performance, while its wing area, combined with flap (Cl max) yields the very low landing speeds (55kts) which is essential for getting into the small strips. Yes the wing mass and turbulence response are both undesirable.The claimed mass fractions don’t look too unrealistic but the performance claims again seem to lack a climb fraction, battery aging fraction, battery operating low temperature fraction, real world considerations such as anti icing etc and again it maybe over reliant on maintaining natural laminar flow.

Yes the motors do look small but assuming they’re axial flux they might not get that much bigger. The prop idea is really novel and technically interesting, but I don’t like the concept of having the pax walking through the prop arc to board the aircraft. Props are real dangerous and Pax can be real dumb….. a combination made safe by a few switches?

One aspect never mentioned by these wannabe companies is the public liability aspect and potential litigation. I once worked with the former chief engineer of BAE Systems Jetstream business and he informed that this market sector was particularly bad compared to others. The basic problem was the operating organisations (airlines and airports) were typically too small/marginal to adequately manage the full range of business and technical risk. Incidents and business failures would routinely spill over to the aircraft provider, who was sued as they represented a very lucrative, indeed the most, cash rich target. The main reason BAESYSTEMS pulled out of the sector was a continuous trading loss coming from legal defence costs. Very few claims against them were successful but they had to pay money out of the business to fight every single one, and there were a lot.
 
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TomcatViP said:
“In a normal aircraft, it makes sense to have this quite complex and heavy mechanism on your propeller in order to operate optimally over the whole range,” said Norcia. “Electric propulsion provides some opportunities to just massively simplify the aircraft. So all four of the propellers are fixed-pitch: the ones in front are pitched for takeoff and climb out, and the rear ones are for cruising.”

With a heavy, complex, expensive traditional engine, it would be silly to double the number just so you don’t have to use variable pitch propellers for takeoff. But with light, simple, inexpensive electric engines, it makes perfect sense to do so, even if it looks unusual.

The front and rear propellers are only both active during take-off and climbing, with the front ones folding away afterwards as then the rear ones take over completely for cruise. It mechanically simplifies things — no heavy duty hinges and hydraulics — and in fact putting the prop back there seems to improve efficiency by about 10%, said Norcia. “It’s pretty cool,” he added. (And they’ve applied for a patent.)
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In the renderings the rear props are folded while on the ground - makes sense since you don't want to let passengers wander into the sharp bits. However those are referred to as 'cruise props' and the front ones as 'takeoff/climb out', so BOTH sets of props are folding, is my interpretation.
I'm glad they have picked a sensible configuration, it is less likely they will go back to the drawing board once they realize all the hidden problems of unconventional layouts (i'm looking at you, Eviation).
I would have thought their vertical tail would be smaller, given how with four electric engines (and with the proper powertrain architecture) they can essentially guarantee there will never be a strong 'motor-out' yawing moment. The big verticals are the bane of conventional twins, it's curious theirs seem similarly sized even though at first sight they have a solution that doesn't need it.
Other things to note: the presence of pusher props means there's no good place for a flap, which is typically inboard. Maybe they don't need one because the wingloading is low enough. But then, as mentioned previously, they have a combination of high aspect ratio and low wingloading, which is precisely what you don't want for flying in rough air.
I wonder where the batteries go...under the floor?
 

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