
Flying-V: Flying long distances energy-efficiently - jcfrei
https://www.tudelft.nl/en/ae/flying-v/
======
mattlondon
More details here:
[https://www.tudelft.nl/en/ae/flying-v/](https://www.tudelft.nl/en/ae/flying-v/)

> "we’re looking into new options to having a rest or taking meals on a plane.
> Offering food from a buffet is one of the options we’re sinking our teeth
> in"

Based on the A380 "promises" of in-flight gyms/casino/salons/creches, I think
we can safely call bullshit on this - we'll just get more seats crammed in as
usual (in economy at least - perhaps first class will get these?). That is
fine - I understand the economics - it is marketing I guess.

~~~
AshleyGrant
You get what you pay for. If you want to pay absolute bottom-dollar prices,
you're going to get absolute bottom-dollar service. If you want to pay more
you can and will get more services. I've hung out at an on-board bar on a 777
in the last year on a flight from Australia to the US, but the ticket cost
over $8k USD round-trip.

It's possible to have a private shower and bedroom onboard an A380 flight, but
you will pay dearly for the privilege.

There's room in the market for both extremes as well as in the middle. I doubt
you'll get a buffet service on a round trip ticket that costs <$500 (trans-
oceanic, at least) as it likely is not economical to offer that. That being
said, there are airlines that are offering improved options even in Economy
cabins... they just charge for it. An example is Air New Zealand's "Economy
Skycouch" [https://www.airnewzealand.com/economy-
skycouch](https://www.airnewzealand.com/economy-skycouch)

So with the possibility that this design could save on fuel costs, maybe
airlines will be able to sell upgraded experiences at prices that are today
bare-bones. Time will tell.

~~~
pkulak
The problem is that now there's so much price pressure on the economy seats,
they are subsidized by the more expensive options. If you want a first class
seat today, that takes 50% more room on the aircraft, you will pay what, 2, 3,
4 times as much money? There's really no middle ground. I'm fine with that,
cause I have a family or four, we're all short, and I'm cheap, but I guess
that makes me part of the problem. :D

~~~
SubiculumCode
Im 6'5" and cant afford 1st class. I am miserable and my knees are jammed
against the seat for hours. 1 inch more and I'd be fine.

There has got to be more tiers

~~~
chrisseaton
Economy, Premimum Economy, Business, First. How many tiers do you want?

~~~
mac01021
He wants to pay 5% more for a couple more inches of leg room.

~~~
chrisseaton
He said he couldn't afford First. There's literally two other tiers in between
that and Economy.

~~~
wanderr
Do any of those tiers allow paying 5% more for a couple of inches of legroom?

------
GuB-42
The biggest issue with true flying wing aircraft is that they are
aerodynamically unstable. They can't be flown by humans, and I don't know how
well they do in unusual configuration, things like stalls, spins, spiral
dives, ...

The rules are different for commercial aviation and for the military. The goal
of commercial aviation is to get people to their destination, as safely and
cheaply as possible, you don't have to fight against an enemy. As a result,
commercial aviation is not very creative. They tend to use proven designs and
incremental improvement.

Making a civilian flying wing aircraft will be a certification nightmare,
which may involve several full-scale prototypes, a new kind of training for
pilots, etc... It is a world where there is still a switch for the "no
smoking" sign in the cockpit that doesn't do anything because all flights are
non smoking now. Removing the button would require re-qualification and it is
easier to leave it there.

The B737-MAX fiasco is another illustration. Just look at how far their went
just to limit change...

I'm not saying that a flying wing commercial aircraft can't be done, but I
have a feeling that the placement of passengers won't be the biggest issue.

~~~
holoduke
That is not necessary true. A flying wing can be made completely stable. The
biggest issue with flying wings is for passengers experiencing much more up
and down movements. Their position is (specially for the most backwards ones)
more towards the wingtips. As you can understand a slight correction will move
you a few meters up or down. Constantly.

~~~
the_watcher
While you are likely technically correct, in terms of passenger experience,
pretty much everyone will disagree with this assessment of "stable".

~~~
briandear
Stability in aeronautics is the tendency for an airplane to remain in
equilibrium without control inputs. A helicopter is unstable, a Cessna is very
stable. Comfort is a different metric. You can have a comfortable helicopter
ride even though the aircraft is unstable. Comfort is also subjective, while
stability is not.

------
challenger22
Wow. The criticisms I've seen about using flying-wing designs for passenger
aircraft (planes that look like the B-2 bomber), are often focused on how bad
the boarding process is for the movie theater seating they require. This
design looks like it eliminates the seating problem pretty well. Flying wings
have been known to be more efficient for a long time; logistics problems are
the devil in the details.

~~~
Shivetya
Yet the image provided is the most radical representation I have seen of the
"flying wing". This is two fuselages in V by initial look. I would still think
that you could simply provide a screen for the interior passengers to have a
view out, from the opposite side of the aircraft. People have done just fine
in the center rows of jumbos so I am not sure that the negative impact is high
as imagined.

The thought experiment to play with is, swap out windows for computer
displays, still with the air gap seen on some planes, but not for all windows
and see what transpires.

~~~
mattlondon
Not sure if there is "reason" for forward facing seats (perhaps crash safety?
If so, why not put them all backwards since that is safest?)

I could imagine seats facing "outwards", with a corridor along the windows.
Kinda like a cinema but the screen is replaced by a row of windows. This way
no one gets to "hog" the window seat (apart from the front row, and even then
others can still see the windows on their walk along the corridors to the
toilets etc). Bonus points for raised stadium-style seating with storage
lockers _under_ the rows at the back.

~~~
sokoloff
We fly an aircraft with "club seating" (two rear facing seats facing two front
facing seats). Experimentally, my son who is prone to airsickness has a harder
time in the rear facing seats [which are closer to the center of mass and
center of lift and so experience less excursions in turbulence than the
forward facing seats, yet he is sicker in the rear-facing seats].

~~~
iamtheworstdev
Those of us prone to motion sickness don't do well when facing the wrong
direction. I have the same problem in trains /subways /limos /etc

------
zymhan
Color me skeptical that an idea that has existed for over half a century still
isn't feasible.

[https://aviation.stackexchange.com/questions/65124/how-
is-a-...](https://aviation.stackexchange.com/questions/65124/how-is-a-flying-
v-more-efficient-than-current-fuselage-over-wing-designs)

[https://aviation.stackexchange.com/questions/12782/why-
are-t...](https://aviation.stackexchange.com/questions/12782/why-are-there-no-
blended-wing-passenger-airplanes-in-operation)

A little more skepticism:

> Sadly for the Flying-V, it will probably fail like the blended wing body
> designs we've seen down the years. It's for the same reason, too: airplanes
> bank as they turn. That's not much of a problem in a conventional airliner
> design, where passengers are never that far from the plane's central axis.
> But as you move further out from that central axis the effect becomes a lot
> more pronounced.

[https://arstechnica.com/cars/2019/06/radical-new-airliner-
co...](https://arstechnica.com/cars/2019/06/radical-new-airliner-could-save-
fuel-but-ride-like-a-roller-coaster/)

There really is nothing new about a lifting-body design.

~~~
throw0101a
One major problem with flying-V is that of stability. However, with fly-by-
wire systems, this is helped with computer control.

The A320 was the first all-digital plane in 1984, so it was unlikely anything
before that could have been developed (and passed FAA/EASA standards).

~~~
mcguire
...and at it's first public outing, the test pilot dropped it in the trees at
the end of the runway. That would have likely killed a new aircraft
manufacturer.

~~~
zymhan
Meanwhile Boeing's mechanical rudder actuator in the 737 caused two verified
and possibly many more crashes during passenger-carrying flights.

------
mywacaday
I wonder what the comfort level would be like in a rough landing being so far
left/right of the center of gravity if the plane was doing a lot of rolling
corrections?

~~~
nradov
That's the problem. When passengers are seated too far from the axis of
rotation they're in for a nausea inducing ride.

Designers could reduce the problem to an extent by building a double deck
passenger compartment and putting the baggage compartments out toward the
wings, rather than the current standard design which places passengers on the
upper level and bags on the lower level. But there are limits to how well that
can scale. I'm skeptical that we'll ever see flying wing or blended wing body
designs used for airliners. Cargo and military applications are probably more
realistic.

~~~
tzs
> That's the problem. When passengers are seated too far from the axis of
> rotation they're in for a nausea inducing ride.

What if the seats far from the axis of rotation faced sideways instead of
forward? People don't seem to be as affected by pitch changes as they are by
roll changes, probably because we are get a lot of exposure to pitch changes
whenever we drive in a hilly area.

~~~
dTal
The angular change is negligible in either case. The problem is you're ping-
ponging vertically. For example, a 3 degree bank correction in an aircraft
with a 70 meter wingspan will move each wingtip by 1.3 meters vertically.

~~~
alkonaut
In the picture, the passenger cabin appears to be using only 1/3 of the
wingspan, so the vertical movement of the outermost passengers (in the last
row) will be much smaller than the vertical movement of the wingtips.

A last row width of 25m is much wider than the 5m of a conventional aircraft,
but much smaller than 70m.

------
duxup
So when I'm in a window seat on a traditional aircraft I see the wings flex a
great deal even on a normal flight.

Are people going to be bouncing up and down all the time?

~~~
skykooler
These wings will necessarily be much more rigid, as they are far thicker than
traditional wings and pressurized. One thing not mentioned here is that that
flexible wings act as a suspension system for an airliner; I'd expect that in
a Flying-V you'd feel more turbulence.

~~~
asdfadsfgfdda
The wings will be more rigid (and will have lower bending loading because the
payload is more evenly distributed along the wing span), but any roll rate
will cause the passengers to experience an acceleration. Maneuvering flight
will not be pleasant for the passengers.

------
aresant
[https://www.jbenad.com/flyingv](https://www.jbenad.com/flyingv) appears to be
the original source and PhD candidate behind the design with great info /
pictures / etc.

------
nine_k
My friends' immediate reaction: "Good luck trying to certify this".

I wonder how bad the odds would be even if an aircraft like this showed
perfect flight safety characteristics (which is not a given).

------
goobynight
This thing looks sick. I wonder if any savings will make its way to the
customer.

> Passenger comfort is also taken into account.

That could mean just about anything, fwiw.

~~~
SketchySeaBeast
They put the lightest, thinnest foam imaginable over the incredibly rigid
seats.

------
perfunctory
Every time I read about increased efficiency I have to think about Jevons
paradox
[https://en.wikipedia.org/wiki/Jevons_paradox](https://en.wikipedia.org/wiki/Jevons_paradox)

~~~
zymhan
Agreed, even if you could reduce fuel consumption by that much, the result
should be lower fares, inducing more people to travel by air.

~~~
mgbmtl
Unpopular opinion, but we could tax fuel at a higher rate than we do now (or
stop subsidizing pollution, depending on how you view it).

------
baybal2
The sole fact that they will only get 20% over A350 in a radically different
design tells just how well optimised are the current designs.

------
Atiim
How is this a new concept when blended wing body (BWB) existed since 1920s
[1], with Boeing X-48 being the latest in 2007-2012 [2]?

1\.
[https://en.wikipedia.org/wiki/Blended_wing_body](https://en.wikipedia.org/wiki/Blended_wing_body)
2\.
[https://en.wikipedia.org/wiki/Boeing_X-48](https://en.wikipedia.org/wiki/Boeing_X-48)

~~~
nicktelford
I think because this is a V-shape, instead of a triangular flying wedge.

------
CoffeeDregs
This is the umpteenth commercial flying wing we've seen and none every fly.
Perhaps this time will be different...

MIT also came up with D8 or double bubble (see:
[https://www.nasa.gov/content/the-double-
bubble-d8-0](https://www.nasa.gov/content/the-double-bubble-d8-0)) but that,
too, was 9 years ago

It certainly seems as though we're stuck in a local minima w.r.t. commercial
aircraft.

~~~
gmueckl
Maybe going to full airliner size in the first step is just too big of a delta
to take on at once. A flying wing business jet might be an interesting
intermediate step (especially interesting for extravagant billionaires who
would like to impress in style, I guess).

~~~
CoffeeDregs
That's a nifty idea: put all the fuel and luggage out towards the wings and
the passengers down the center. No more discomfort for passengers (during
turns and turbulence) and you'd still reap the benefits of the BWB design.
Though this would block window views...

------
tempestn
Looking at the design, the first thing that occurred to me is that it _looks_
like the frontal surface area would be increased compared to a traditional
commercial jet with the same wingspan, which I would expect to negatively
impact fuel efficiency. I did a bit more thinking and some reading to try to
determine why this isn't the case.

For one thing, while the split fuselage in the images appears similar to that
of a conventional airliner, I expect it would actually be considerably shorter
than that of a jet with comparable capacity, the reason being that much of the
luggage and equipment that would normally be stowed below the passenger
compartment could instead be relocated to the center of the 'v'.

You would still have somewhat more frontal surface though I would think.
Perhaps this could be outweighed (no pun intended) by weight savings and lower
surface area. Although I wonder if some of the savings would have to come from
flying more slowly, which this design might facilitate.

I don't know anything much about aeronautics though, so would love input from
someone who does!

------
Johnny555
Nobody is building this plane (yet), KLM is just funding more research, any
commercial airliner based on this technology is likely decades away. The 787
took about a decade to develop and it's based on a more traditional platform.

------
jillesvangurp
Hmm, looks like an x-plane screenshot. It wouldn't surprise me if they've been
prototyping with planemaker (included with x-plane).

IMHO interesting concept but the thing to be investing in would be electric
engines (hybrid or battery) as that will cut fuel costs a lot more
potentially. 20% is an incremental improvement and potentially not good enough
by the time this gets productized and never mind the time when this gets
retired a few decades later (in the best case). So, in short, I think this
won't fly (bad pun, sorry) because it's not anywhere near good enough by the
time it can reach the market (15+ years?).

~~~
nwah1
A lot of the proposed efficiency improvements involve new engines, new fuels,
or new materials. This is a new design which could stack on top of any of
these other improvements. Including a hybrid or electric engine.

~~~
jillesvangurp
Maybe but the primary driver of this design is the fuel tanks and weight
distribution as well as the need for having big heavy jet engines.

This thing still takes about 140 tonnes of fuel. That's a lot of money to fly
from A to B using a plane that is still a decade+ away. All I'm saying is that
20% cost reductions is not nearly ambitious enough for that type of long term
project given the stuff that is already happening today and given the stuff
that is likely to happen in the next decade.

------
a3n
The engine placement in the image looks like if one engine has a catastrophic
failure it might take out the other engine.

Engines have taken out hydraulic control lines in the past.

~~~
nradov
The engine placement is also problematic for maintenance. Airlines prefer to
buy aircraft that their mechanics can service with just a short ladder. That's
one of the main reasons why all recent designs have engines only under the
wings.

~~~
sokoloff
If it gave them a 1% cost advantage, airlines would be happy to have mechanics
on scissor lifts or in buckets.

------
justfor1comment
Why does it look less aerodynamic than a normal plane? Isn't a rocket or
missile like shape the most aerodynamic one? Planes are pretty close to
rockets with thin wings for maneuverability. Fling V has so much surface area
being pushed against the air, I am honestly surprised at their claim of being
20% more fuel efficient.

~~~
Leherenn
In term of pure drag, you're right, you want to reduce the surface and that's
not what this design does.

However, for aerodynamic efficiency it is the lift/drag ratio that matters.
And while in a normal airliner the body provides very minimal lift, here it's
basically a wing and thus generates a lot of lift.

The end result is that while the drag is probably worse, lift is likely
improved enough to compensate.

(Also, drag might not be that bad given you do not have a tail, which is
pretty awful aerodynamically speaking)

------
trhway
if tube and wings design is to change, i think it will be some less radical
changes than flying wing, more along the lines of transitioning the tube into
the lifting body, while may be not the full way along the Burnelli
[http://www.burnelliaircraft.com/wp/](http://www.burnelliaircraft.com/wp/) ,
instead more like the modern version
[https://en.wikipedia.org/wiki/Aurora_D8](https://en.wikipedia.org/wiki/Aurora_D8)
:

"The aircraft is designed to be over 50% more fuel efficient[1] compared to
aircraft currently under production."

------
FreeInFlorida
Twice the fuselage weight, cost for same number of seats, plus two gigantic
engines located well aft of Center of Pressure.

There’s a good reason we don’t see any aircraft with a design like this today.
It doesn’t work financially or aerodynamically.

------
lallysingh
So how are the dynamics of this thing in the air? Easy to maneuver? As safe?

~~~
tomstockmail
I'd be interested in how they would manage weight distribution as well. Will
the plane still fly in a situation where passengers on one side of the
aircraft need to be on the other side?

------
leeoniya
that looks like a deicing SNAFU just waiting to happen. that's a lot of
surface area that has to be de-iced to ensure nothing breaks off and enters
the engines at the back.

------
anordal
Are the wings at the back doing anything useful so far aft of the center of
mass, uh, behind the rest of the craft?

------
sbjustin
I'm curious what kind of impact a design like this would have on pilots
getting checked out in the aircraft.

~~~
jayrot
It would be a significant time investment to be checked out in a radically
different type like this, but not impossible. It mostly comes down to the
systems, avionics, and procedures which can be radically different already,
even in similar-looking planes.

~~~
8draco8
I also wonder about engine placement. Engines on top will push the nose
downwards in case of adding more trust. There is also issue of stalling on
ascend. On ascend, wings would very easily obstruct air going into engines,
reducing their power. Also currently aft-mounted engines require vertical
stabilizer to be above them to counter act the forces generated by the
engines. I don't see any vertical stabilizers in this concept.

------
LoSboccacc
after some clicking you can see the '2% lighter' claim on a demonstrator,
here: [https://www.jbenad.com/flyingv](https://www.jbenad.com/flyingv) which
makes me even more dubious about this whole thing; the claim is that this
configuration fits in the dimension of the airbus is compared to, so by logic
alone the increased surface area should end up in a greater weight, and that's
without considering the increased structural elements that are required to
avoid flexing and twisting of the two heavy sections to which the rear wings
are attached, which have a lot more momentum than your usual wings, since they
carry more weight and farther than the center of mass/rotation.

I also wonder where would the fuel be stored. needs to be around the center of
mass and lift, to avoid the com shifting around as the planes flies. and there
aren't wings there conveniently placed near the com to store it, so, is it
going to end up below the passengers? that'd be a huge safety hazard.

~~~
Theodores
Fuel is fuel, wherever it goes there is a safety consideration.

The last crash I saw on the news had something nasty going on with the engines
hitting the tarmac, the above wing placement of the engines is a safety
feature as I see it, even though that design choice is more out of
consideration for noise - it should be quieter for those living under a flight
path.

From the evolution of the bicycle to the mountain bike I can remember that a
big, thin-walled tube is stronger and lighter than a narrow, thick-walled
tube. I know planes are different, but bigger does not automatically mean
heavier.

You could have all of the fuel at the back, behind the passengers and engines.
The flight control surfaces and some thrust vectoring could accommodate that.

A U.S company called Boeing know a thing or two about making automatic systems
for mitigating against a less than perfect centre of gravity. They went for
less than ideally located engines rather than less than ideally located fuel.
Allegedly there have been a couple of hiccups with this system but the general
idea is that not even the pilots know that there is a computer accounting for
changes in centre of lift/gravity, it just works.

On Airbus planes it has always been fly by wire. By 2050 - when this V thing
is supposed to go into service - the idea that a human should fly a plane will
seem daft, if the computer is doing it all anyway then the plane does not have
to be dynamically stable or even balanced from side to side. It should be able
to precisely balance out the shear forces no matter what the conditions. You
could even turn the thing without banking.

Tongue in cheek criticisms aside, it is better than my student project and a
nice thing for KLM's 100 year celebrations.

~~~
3JPLW
> You could have all of the fuel at the back, behind the passengers and
> engines.

That would cause quite the difference in handling between takeoff and
handling. The fuel tanks span the length of the fuselage in this design — and
I'm sure that's intentional.

------
AFascistWorld
So what the speed, this doesn't seem like it can fly as fast, which naturally
reduces fuel needs.

------
runxel
If only Reimar and Walter Horten could see that! Really great to see these
advances in aviation.

------
shock
The article is titled "KLM and TU Delft join forces to make aviation more
sustainable".

------
SteveCoast
If the engines are over-wing you know it’s nonsense.

~~~
hawski
Could you expand why for a layperson?

~~~
tropo
I wouldn't say nonsense, but the problems are different and maybe worse.

Below: Engines can strike the ground. There is more debris ingestion, ranging
from sand and burst tires to people and baggage carts. Noise regulations are
harder to satisfy.

Above: Failure causes nose-up (as power is lost), which may lead to a stall.
The aircraft sits lower in the water after a water landing. Being nose-up may
put the intakes in slow turbulent air flow, killing performance and possibly
stalling the intakes. Ice and rain may come off the body, to be ingested by
the engines.

Some things could go either way. Maintenance is going to involve a crane or a
jack to get the engines off.

------
fernly
Sorry, but this thing, head on, is pure FSM.

------
feniv
From the title, I thought this would be about an airline flying using the
V-formation like geese or military jets to reduce fuel.

------
riffraff
so, why is the A350 the most advanced plane? I had not heard this claim
before.

~~~
SteveCoast
It’s the newest-ish airframe until the carbon 777 flies.

------
kazinator
> "integrate the passenger cabin, the cargo hold and the fuel tanks"

"Flying Pinto".

------
NikolaeVarius
> Its improved aerodynamic shape and reduced weight will mean it uses 20% less
> fuel than the Airbus A350, today’s most advanced aircraft.

That is such a meaningless claim.

~~~
anarchy8
Why? That's a perfectly quantifiable claim.

~~~
NikolaeVarius
All airplanes are aerodynamic. There needs to be a mention of what exactly is
happening to cause those fuel savings.

I highly doubt that those numbers are trustworthy considering how closely we
are scraping fuel efficiency numbers, unless there is some performance metric
they aren't mentioned that has degraded.

~~~
challenger22
It has been known for a long time that flying wing designs are inherently more
fuel efficient than typical passenger airline fuselage designs.

~~~
lazyjones
But in this extreme case of the fuselage being inside the wing and making it
much thicker than typical and necessary, this isn't necessarily true, at least
it's not obvious.

If this design actually provides the claimed results, connecting 2 such wings
(one behind the other) with a long fuselage (i.e. >\---> which would incur
almost no additional drag and twice the lift) would be even better, no?

~~~
challenger22
Think of it this way: A cylindrical fuselage provides no lift (except for the
lift from its angle of attack flying obliquely through the air), only drag. If
you can design the aircraft in such a way that all exterior surfaces
contribute to lift, that would be ideal.

The "\---" portion of your idea provides no lift, only drag.

------
dmitrygr
The main problem with flying wings, and probably this design too, is that they
are inherently unstable, and without very precise computer control they are
uncontrollable. Compare to modern planes that a good pilot can fly and land
with zero computers, given some effort. (They are stable, and with no control
inputs at all just keep flying in same attitude as they are currently in)

In a flying wing, computer failure is a certain airframe and passenger loss. I
don't know any engineers who write flawless code. Do you?

~~~
2Ccltvcm
This is patently false. In fact you should delete this post in its entirety
because it's just wrong. Don't make these things up and post them as fact.
Flying wings easily fly without _any_ computers whatsoever. They are
inherently aerodynamically stable. Only manual elevon inputs by humans are
actually required and it is quite easy to control unless your center of
gravity is too far back. The CG is usually around 70% of the way to the front
from the back.

~~~
umvi
Instead of spending half your comment saying how wrong GP is, why not provide
some compelling evidence? I was under the impression that flying wings are
indeed more unstable than traditional airframes.

For example:

[https://en.wikipedia.org/wiki/2008_Andersen_Air_Force_Base_B...](https://en.wikipedia.org/wiki/2008_Andersen_Air_Force_Base_B-2_accident)

> After the wheels lifted from the runway, which caused the flight control
> system to switch to different control laws, the erroneously sensed negative
> angle of attack caused the computers to inject a sudden, 1.6‑g, uncommanded
> 30-degree pitch-up maneuver. The combination of slow lift-off speed and the
> extreme angle of attack (and attendant drag) resulted in an unrecoverable
> stall, yaw, and descent.

This seems to support GP's assertion that "without very precise computer
control they are uncontrollable" and "computer failure is a certain airframe
and passenger loss"

~~~
0xffff2
Absolutely no one denies that the B-2 in particular is unstable, but it is one
particular model designed to a particular set of requirements that are vastly
different from those for a commercial airliner. It seems that the general
public have internalize "the B-2 and F-117 are inherently unstable" as "flying
wings are inherently unstable", which is incorrect.

~~~
thatswrong0
To be even clearer, these two planes were designed with the goal of having the
smallest radar cross-section possible. The lack of aerodynamic stability was
worth the trade off (esp. since it could be compensated for by flight
computers).

