
NASA reveals what the final X-57 all-electric X-plane will look like - prostoalex
https://newatlas.com/aircraft/nasa-images-final-x57-electric-x-plane/
======
mfsch
In the video they tout the X-57 as a contribution to the “urban air mobility
market”, arguing that small aircraft can decrease commute times and avoid
congestion. This seems very backwards to me. Cars are already very inefficient
in their use of space, since they require large amounts of space around them
when they are moving at speed. I expect this issue to be significantly worse
for aircraft, with the speed they are moving at, the safety distances needed
to avoid crashes, and the volume of air they are disturbing around them. While
they can potentially make use of the vertical dimension for more space, they
still have to move through the surface layer for take-off and landing and will
want to stay close to the ground for short trips. And they potentially add a
lot of noise to an already noisy urban environment.

I’m all for ambitious research projects pushing the boundaries of electric
flight, and there’s probably reasonable use cases for planes like the X-57.
But a sustainable urban transport future looks much more like buses and
bicycles rather than small electric aircraft.

~~~
jillesvangurp
You are ignoring the fact that cars have to navigate what is basically a set a
of 1 dimensional corridors on a 2 dimensional plane. Airplanes don't have
these limitations and can fly point to point at their choice of altitude.

Currently most of the congestion in aviation is around airports which are
necessarily optimized for large jets. With a small airplane, you can fly to a
much larger variety of airports, around ~50K world wide and it's relatively
straightforward to build even more of them as needed.

Noise is a function of propeller size, rotation speed, and engine noise.
Simply put, lots of small propellers rotating at faster speeds driven by
electrical engines are a lot less noisy than larger props driven by combustion
engines. The physics around this are complex and involve things like the speed
of sound of the tips of the propeller (you break that limit at lower rpm for
larger props), the mass and thickness of the propeller, vortices, etc.
Basically, all of that improves with smaller props.

Compared to a loud helicopter, an electrical plane at the same altitude could
be a lot less noisy to the point where in a busy city you'd hear one but not
the other above the ambient noise.

~~~
athenot
> cars have to navigate what is basically a set a of 1 dimensional corridors
> on a 2 dimensional plane. Airplanes don't have these limitations and can fly
> point to point at their choice of altitude.

That's not entirely correct. Planes also have corridors in the sky. Just like
roads, there are the highways (with different altitudes for different
directions) and slower lanes for smaller aircraft. And airports are basically
a confluence of many lanes, which requires a coordination (air traffic
controllers).

[https://en.wikipedia.org/wiki/Airway_(aviation)](https://en.wikipedia.org/wiki/Airway_\(aviation\))

~~~
jillesvangurp
Depends on what class of airspace you are in and weather you are flying under
IFR or with some kind of flight following & flight plan. But even then the air
ways can be stacked vertically.

If you are flying vfr and in an airspace where that is allowed, you can pretty
much go where you want as long as you stay away from controlled areas.
Basically most helicopters fly VFR. The recent accident with Kobe Bryant
involved a VFR flying helicopter flying into fog in LA.

~~~
bdamm
True, but to provide reliable commuting you pretty much have to fly IFR,
especially in a place like SF Bay or LA. This is because often marine layer
clouds don't clear until 10am and people want to be at work long before then.

It may be possible to do a lot more to improve the availability of IFR
approaches and routes if we factor in automated systems. It's going to take a
lot longer to build more airports, but I can tell you that pretty much every
airport manager in the United States will be thrilled to face that problem.

------
redis_mlc
The X-plane program does fundamental research. All military and commercial
aircraft have benefited from that research, in the same way WW2 German designs
also influenced the world.

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](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.

~~~
TeMPOraL
> _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._

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).

~~~
redis_mlc
The FAA doctrine is "one level of safety."

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?

~~~
jsight
The Robinson R44 costs ~500k USD.

~~~
aDfbrtVt
I think the comment is referring to something more in the range of a new-ish
Bell 206

~~~
jsight
I'm aware of that, but the comment blamed this on needing to be "treated like
operating an airliner". In reality, tourist helicopters are much better (and
more expensive) than an R44 principally for reasons other than the FAA's
treatment of them. Also, I believe that the Bell 206 is well under $2 million
as well.

------
GordonS
Aside from the pictures, the article was a bit lacking in information.
According to wikipedia, it only seats 2 people, has a maximum range of only
100 miles, and a maximum flight time of only 1 hour. The batteries weigh
390kg, which sounds like a lot of weight relative to the small size of the
plane.

I get that electric flight is new, and it's going to take a long time before
anything happens at scale, but given the limitations (and of course the fact
you need an airstrip at either end of your journey) I can't help but wonder
who is going to actually buy them, and what they would do with them?

~~~
PaulRobinson
The X in X-Planes stands for "eXperimental". The history of them goes back
within the US to 1946 and as the list [1] of vehicles shows, these aircraft
are intended to test concepts and ideas, not provide a sellable solution to
the market.

Whilst most are betting that commercial electric in the air is going to be
VTOL - and they do address the low endurance and runway issues you highlight -
there are efficiency gains for longer distance in fixed wing designs, and
you're going to have to think about electrification of that class of vehicle
at some point.

Put another way: we don't use helicopters for all passenger transport for a
whole bunch of reasons, EVTOLs don't fix all those reasons, and so if you want
to keep fixed wing aircraft around as a concept AND you want to use electric
motors, at some point you're going to have to think about experimenting with
electric passenger-carrying fixed wing aircraft.

Thus: the X-57.

You might wonder what the purpose of an experimental aircraft in this config
is, if the eventual goal is to build airliners that can move lots of people.

Well, the X-1 was no Concorde, but Concorde would not have happened without
the X-1. And so it goes...

It's OK then to think of the X-57 to an airliner of the future, as the X-1 was
to Concorde. It's a whole set of interesting experiments that will validate
some hypotheses, refute others, and we move along another step towards a
better future.

Seat count will get higher, endurance will improve, batteries will get
lighter, and within 20 years, who knows where we'll be.

[1] [https://en.wikipedia.org/wiki/List_of_X-
planes](https://en.wikipedia.org/wiki/List_of_X-planes)

~~~
GordonS
Thanks, your comment makes a lot of sense.

I do understand this is experimental, but I just assumed the end goal was to
do a licensing deal of some sort with a partner than would sell a
commercialised variant.

My assumption (yes, another one ;) was that electrification would require
baby-steps towards commercialisation in order to continue to fund the kind of
progress you speak of - in the same kind of way we saw with cars, where
initially they were expensive, had a very short range, there was very limited
infrastructure etc, but they were still an option for a small market segment.

~~~
numpad0
From the article, apparently the purpose of the whole program is to immunize
FAA of funky startup planes.

With a NASA prior art as baseline, FAA people could judge what document is
required, which part is novel and which one of “chief” is just a functional
addict.

------
mrfusion
Meta: I haven’t seen this much negativity for an exciting new technology from
HN before. It’s kind of bizarre.

~~~
leetcrew
it's transportation research money that isn't being spent on bike lanes,
buses, or rail.

~~~
rexreed
In our part of the US, money for bike lanes, buses, and rail comes from states
and local jurisdictions, not from federal funds. The portion of money NASA is
getting from this does not take away from multi-modal transportation
investment at the local level.

~~~
leetcrew
sure, but it's a common thread. notice how you see similar comments on
articles about electric cars. HN hates to see money spent on improving forms
of transportation that are not bikes or public transit.

------
obmelvin
Does anyone have enough aerospace knowledge to comment on the design? Comments
on the article seem skeptical on placement of the propellers, but I have
absolutely no expertise here to make any assessment myself.

~~~
oliveshell
Here’s a NASA paper on the propeller arrangement:

[https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/201600...](https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20160010105.pdf)

Apparently the small propellers’ primary function is “to act as a high-lift
device [1]” rather than to generate thrust.

They allow the wings to have a higher aspect ratio (i.e., be ‘long and
skinny’) for reduced drag. Without them, such a wing would give undesirable
low-speed handling characteristics and a higher stall speed.

Also, their speed can be varied independently and quickly by computer to
compensate for turbulence and wind gusts.

Looks like quite an interesting design that plays to the strengths of electric
motors.

[1]: [https://en.wikipedia.org/wiki/High-
lift_device](https://en.wikipedia.org/wiki/High-lift_device)

~~~
eternauta3k
Do you mean "lower stall speed"?

~~~
bathtub365
A higher stall speed means you need to go faster not to stall and is an
undesirable property. Lower means you can go slower before stalling

------
starpilot
Really recommend watching the short video at the end of the article. It shows
them fiddling with a 3d-printed prototype of the folding propeller, and some
of the CFD analysis of the prop wake - wing interaction.

------
sergeykish
Cruise efficiency increased from 0.7 km/kWh to 2.9 km/kWh (13 nmi/gal AuGas to
equivalent 51 nmi/gal AuGas).

Better than ICE car!

------
JoeAltmaier
Problem in the article with the caption? It says the picture is in 'cruise
mode' but when cruising at altitude, the X-57 folds the small electric motors
into the wing nacelles and leaves only the two wingtip props active. Did I
miss something?

~~~
roelschroeven
No, the propellors fold into the motor nacelles. Not the motors into the
wings.

~~~
JoeAltmaier
Thanks!

------
GordonS
With cars, we've seen a lot of companies going the hybrid route, combining
multiple small electric motors with a combustion engine. I'm curious if the
same could be done with aviation - perhaps a turboprop or jet engine to get to
cruise altitude, then electric engines taking over.

Anyone know if there are any promising hybrid planes on the horizon?

~~~
spaceandshit
Only one of many competitors: [https://www.rolls-royce.com/media/press-
releases/2019/06-11-...](https://www.rolls-royce.com/media/press-
releases/2019/06-11-19-rr-announces-new-hybrid-electric-flight-demonstrator-
to-be-built-with-brandenburg-partners.aspx)

------
sintaxi
"spreading congestion" is not the best marketing pitch.

------
rcpt
How different is this from what Joby is doing?

~~~
spaceandshit
Joby makes the electric motors for this aircraft.

[https://en.wikipedia.org/wiki/Joby_Aviation](https://en.wikipedia.org/wiki/Joby_Aviation)
(title image)

------
zelienople
Humans need a basic amount of exercise for health. It is hard for me to
understand how someone with a functioning brain would look at traffic
congestion and propose this solution, particularly with the codicil, "it's
already benefiting taxpayers".

No, technological developments that cannot possibly be used by anyone but the
wealthy few, no matter how energy-efficient, are not a sane solution to urban
transportation issues.

The solutions are more prosaic:

(1) Reduce population, population density, and the product of population times
lifestyle. We have exceeded the carrying capacity of the planet, and our
science is telling us that unequivocally with a cacophony of data from coral
reefs, the status of the ocean, the loss of insects, and many other sources.
We must control our own numbers. There is no technological alternative to
that.

(2) Create spaces and routes that foster personal human-powered
transportation, such as bicycling. Separate the cars from the people to stop
the carnage and remove legitimate safety arguments against bicycling.

(3) Make public transit extensive and free. Stop extracting a pound of flesh
from the poorest for every ride that they must take to get to a job that
doesn't pay a living wage. The inequity of wealth distribution in our society
has passed all limits of sanity. Incentive works great in small "c"
capitalism, and we need to make sure that mom and pop outfits and very small
businesses have the incentive to innovate and produce, but there is no need
for the unlimited capitalism that we have now. Take a few pennies out of the
pockets of the uber-rich to pay for transit.

(4) Stop the propaganda, herein represented by NASA's usual BS about how we
all benefit from their R&D. Organ transplants my fanny. The only thing this
kind of transportation is going to do is to further increase the divide
between ordinary people and the ultra-rich who pay no taxes in any case.
Taxpayer-funded research into new toys for the CEO. Yay.

We are brainwashed into a profligately wasteful, unnecessary, insanely-self-
focused lifestyle. Mass media makes us feel bad so we'll go out and spend all
our money on the latest stupid thing that will break in a year or less and
we'll throw out. All the while we are striving to fill some artificially-
stoked hunger for more: more money, more things, more waste and more
destruction.

The X-57 feeds right into that brainwashing. It will be our end.

~~~
JoeAltmaier
Its actually pointed at reducing the entry cost of flying. So ultimately not
for ultra-rich.

NASA spends peanuts, and part of those peanuts is spent on fostering
innovation. When I hear "Lets just feed the poor!" I feel ill. We're not so
desperate we can't do right by our people, without tearing down everything
else that's good. NASA's budget isn't going to feed the poor for more than 10
minutes.

------
mlindner
Not a fan of this design. The future for electric motors on aircraft is ducted
fans, just as are used on jet engines.

~~~
mrfusion
Can you expand on that? I’ve wondered the same thing.

~~~
atrettel
Propeller-driven aircraft perform best at subsonic speeds (slower than the
speed of sound). This is because the blade tips of the propellers approach the
speed of sound at faster speeds, and this greatly increases the drag on the
propeller blades, among other things. This is why after World War 2 propeller-
driven fighter craft fell out of use, since they could not get much faster
without major issues.

Modern passenger jets operate in the transonic range (0.7 to 0.8 times the
speed of sound). This range is a bit too fast for propellers and pretty much
requires jet engines or something similar. Using props for passenger planes
would reduce their speed as experienced by passengers today. I believe this is
what the author is referring to.

------
alkibiades
does the have anything to do with actual space travel or just a hobby project
for global warming?

~~~
redis_mlc
NASA did abandon aviation for space, shelving the X-plane program for about 2
decades, which was a huge loss.

It's great they're back, and have been doing fantastic work in fundamental
research that private companies don't get around to: hypersonic vehicles,
small-airplane electronics, now electric.

