They're generating lift at low speeds by using the array of small motors, and then optimizing the wing for cruise lift. It's really brilliant. And it'll result in better handling in turbulence too. Frankly I'm stunned at the direction they've gone here, it's really remarkable and is a major shift in approach to aerodynamics that has huge implications across the industry.
I though the regulatory hurdles around "urban air" come straight from the need to protect people and property from the dangers of a) falling aircraft (which would become a real concern as the use scales up), and b) excessive noise. And I'd guess c) dust clouds. We'd have to invent propulsion that's much more quiet and doesn't push air around for air taxis to make sense. So this would make the root cause of those regulatory problems be technology problems (or perhaps even physics problems).
What that means is that:
1) a flying car is going to be treated like operating an airliner if money changes hands to carry passengers. To give you an idea of what that costs, consider that an adequate tourism helicopter is $2 million.
2) otherwise, there's a rule for built-up areas that requires flying 500' over people and structures. That doesn't count for landings on regular airports and EMS helicopters on top of hospitals, but does pretty much everywhere else. Not terribly useful for commuting downtown.
3) the FAA regulates airspace and airports, but municipalities generally say no in urban areas when private citizens ask to operate helicopters off-airport. Steve Jobs found that out when he tried to get permission to use one for personal "urban air mobility" either in Palo Alto or Cupertino.
So to conclude ...
If you wanted agreement from the FAA and municipalities to do the "urban air mobility" thing, you'd need to start with what I wrote and devise a compelling argument that satisfies their concerns. Note that wasn't done with drones, and look at how restrictive the rules are now. It will be far worse if you want to charge money to carry passengers.
Rightfully so - passengers expect to embark, travel and disembark without making the headlines.
And you need a plan for what happens after the first accident that kills a passenger. Because not just one air mobility company, but all companies, will be mercilessly hammered by the FAA. Can you afford to shutdown for a year or two while the NTSB and FAA do their thing?
You also can't compare operating costs of a military vs. civil aircraft. VERY different priorities, military aircraft have dramatically higher requirements due to where they operate (desert sand anyone?) and their mission. EVERYTHING gets inspected, components are designed to be performant like Formula 1 race cars and not necessarily for lowest operating costs. It's like comparing an M1 tank, which gets 0.5 mpg, to a Ford F150.
> What's weird about mounting propellers at the end of the wing is that you lose half the lift of the propeller wash over the wing, over a normal placement.
This is nonsense, there's no rule of the thumb that states any random wing reduces prop thrust by 50%. You must calculate it. It's a very complex unsteady flow field dependent on all of the geometries involved. It will vary on flight condition obviously.
> informal aerodynamics student
I'm sorry but the average pilot's understanding of aerodynamics is very poor. I've seen blatant mistakes in flight manuals. At the least you should know how to explain what Reynolds number and Kutta condition are before diving into these discussions.
We’ve had multi engine turbo props forever, I don’t understand why the osprey is more comparable than a traditional propeller aircraft.
[1] https://www.cdc.gov/homeandrecreationalsafety/water-safety/w...
Electric motors are inherently much simpler than internal combusion, but I don't know how they compare to turbofans.
But it's definitely worth the research and working out design and other aspects is a good thing for research in other aviation areas like drones.
But it's pretty obvious that they don't have a problem with lift during cruise, so why does it matter that you lose some lift? I really doubt they would design the wing that narrow if simulations showed that lift was an issue, and I think these guys know what they're doing, so if you think this is an issue I think you need a stronger argument.
That's the whole point of the small propellers, to gain that lift during take-off and landing, while not producing drag during cruise.
> And we know from the Osprey that complex propeller systems fail too often. A dozen propellers means an order of magnitude more inspections, replacements, ground time (AOG), etc.
But we're already seeing from small electric planes entering the market now that they have much lower maintenance and operational costs. Electric motors are fundamentally more reliable and low-maintenance than other alternatives.
So it can make sense to spend some of those saved costs on increasing the complexity a bit to increase efficiency and redundancy.
I also don't agree that this propeller system is complex or would require an order of magnitude more inspections. As mentioned, electric motors are extremely simple and reliable, and the small propellers have a high degree of redundancy, so you could design the system to allow for failure of one or two motors without affecting operations. The folding mechanism for the propellers looks to be very simple.
A way to think about it could be: ensuring that you have high enough safety margins require a certain amount of complexity. You can either spend that complexity on two engines that require a high degree of internal complexity and maintenance, or you spend the complexity on 10 motors that are extremely simple and are allowed to fail.
I also think the comparison with the V22 Osprey is extremely flawed. The purpose of those complex rotors have an entirely different purpose, and it's certainly not for redundancy or efficiency, and the engines have wildly different properties from electric motors.
> Additionally, there is no "urban air mobility market" in the USA, and never will be, due to regulation and insurance requirements.
It's pretty bold to say "there never will be". But anyway, it's just a vision, something to strive for.
What we do know is that it's very likely that electric planes will lead to higher utilisation of small airports. They're cheaper to operate and more silent, which significantly reduces the barrier to using these kinds of airports. At first we'll just see pretty standard looking electric planes in existing small airports, but as this market grows, I think you'll see both the planes and the airports change to optimise for this new/growing market. No, maybe you won't have a flying car in your garage, but I find it very likely that you can drive/bike/walk to something like a bus/train-station to catch a small 10-20 passenger plane somewhere. And though that would be impossible with the regulations today, the regulations will adapt iteratively, allowing the small airports to move closer and closer to urban centres, with shorter and shorter runways.
There's no path to that vision in US urban areas.
New airports will not be built near urban centers due to lack of land and NIMBYs. So you have a significant last mile problem.
Everything seems possible when you don't know anything.
X-57 is fundamental research, not an effort to create a final product. The closest program similar to it is the X-29, which investigated forward-swept wings, canards and augmented computer systems to control them. (Nobody wants forward-swept wings because a failure in wingtip rigidity or the computer software destroys the structure.)
As a commercially-rated airplane pilot and informal aerodynamics student, I think the wingtip propellers are questionable, and the retractable inboard propellers sound like a maintenance and operations nightmare.
What's weird about mounting propellers at the end of the wing is that you lose half the lift of the propeller wash over the wing, over a normal placement.
What's misunderstood about wing tip vortices is that regardless of what the loss is, that flow comes from the entire wing producing lift, so is unavoidable. There are already passive techniques like winglets and fences to direct vortices that don't require daily maintenance.
And we know from the Osprey that complex propeller systems fail too often. A dozen propellers means an order of magnitude more inspections, replacements, ground time (AOG), etc.
At $83,000/hour to operate, a V22 Osprey is more expensive than an A380. Also, read the section on "Design Challenges":
https://en.wikipedia.org/wiki/Bell_Boeing_V-22_Osprey
Additionally, there is no "urban air mobility market" in the USA, and never will be, due to regulation and insurance requirements. In a showdown between the FAA and Uber, the FAA will always win, and the FAA reserves the perogative to change its mind later, as in drone regulation.
To give you an idea, it was easier to start SpaceX than it would be to get the FAA to allow "urban air mobility." So regulation is the real challenge, not technology.