
Boeing's folding wingtips get the FAA green light - mpweiher
https://www.engadget.com/2018/05/18/boeing-folding-wingtips-faa-777X/
======
Someone1234
I'm glad the FAA does what they do. While it is easy to hand wave away their
concerns, it is better to over-spec it now and to test the design than to just
let manufacturers put "alpha" products into commercial usage and only fix them
after a body-count.

If driving/vehicles/roads were held to the same or a similar standards to
aircraft there might be fewer accidents and deaths today.

Ironically self-driving is held to a much higher standard than regular
driving; which is appreciated but further makes one question why regular
"dumb" vehicles are so under-regulated (the analogy that springs to my mind is
when HTTPS with a self-signed certificate used to be treated much worse than
regular HTTP, it took years to treat HTTP as the insecure connection it is,
manual vehicles are the same way, something that has been around so long we
ignore its safety issues).

~~~
sunflowerfly
Bringing the same rules to light aircraft as airliners has actually made them
less safe. Bringing a new four place plane to market has been cost
prohibitive. The majority of new planes built today were designed in the 50’s
on slide rules. Imagine if we were all still driving 50’s era automobiles.
Luckily, the FAA loosened these rules this week.

~~~
lisper
> The majority of new planes built today were designed in the 50’s on slide
> rules.

That's not true.

Of the 15 most popular light aircraft models built in 2015, only one was
introduced in the 1950s: the Cessna 172. And even that one underwent a pretty
substantial overhaul in 1998. The most popular light plane sold in 2015 was
the Cirrus SR22 with 270 units sold. The SR22 debuted in 2001.

Source: [http://www.fi-aeroweb.com/General-Aviation.html](http://www.fi-
aeroweb.com/General-Aviation.html)

~~~
romwell
>Of the 15 most popular light aircraft models built in 2015, only one was
introduced in the 1950s: the Cessna 172.

It's disingenuous to say that and not talk about numbers. There were over 44
thousand of them built, and they are literally _the most produced aircraft
ever_. Cirrus is a blip on the radar compared to Cessna.

At 300 planes/year they will not catch up with Cessna in a _century_ even if
Cessna ceased to exist today!

In fact, the top six most produced civilian aircraft ever _that are still in
production_ are[1]:

Cessna 172 (1950's)

Piper PA-28 (1960's)

Cessna 182 (1950's)

Cessna 152 (1950's)

Antonov AN-2 (1950's)

Beechcraft Bonanza (1950's)

Do you have the statistics on the market share of the "slide-rule" planes
today? Not as a percentage of planes _being built or sold_ , but of the ones
in service. I'd bet on them being the majority.

[1] [https://en.wikipedia.org/wiki/List_of_most-
produced_aircraft](https://en.wikipedia.org/wiki/List_of_most-
produced_aircraft)

~~~
lisper
No, it is not disingenuous because the topic at hand is "the majority of new
planes built _today_."

Obviously if you look at production through all of aviation history you are
going end up overweight in older models. But that is just a reflection of the
fact that planes are generally designed and built to last. It has nothing to
do with the current state of the art, which is what the OP was lamenting.

~~~
romwell
OK. You are correct, you have refuted the point that the majority of planes
built today are of older designs.

The point we were discussing is that excessive regulation on light aircraft
prevents innovation by driving the cost prohibitively up and thus leading to a
decrease in sales of new designs.

It is not clear to me that the argument that the industry overall is less
safer is invalid if most of the planes flown are old, and if over-regulation
of light aircraft is the cause of that.

We do need the statistics on the numbers of old-design planes in the air,
together with the pricing data, statistics on sales which include old planes,
etc.

~~~
lisper
Wow, new planes cost more than old planes. Who knew?

~~~
romwell
New planes today cost more than new planes used to cost back in the day
(accounting for inflation), which creates more demand for older planes.

Cessna 172 cost under $9000 in 1956 when it was introduced, which is about
$80K today when accounted for inflation.

Do you know of any similar _new_ aircraft in the same ballpark? Last time I
checked, $50K still gets a _Cessna 172 built in the 70 's_. A new Cessna 172
seems to be north of $250K, depending on configuration.

Cirrus SR22 is north of $550K.

Civil aviation has definitely become a richer man's game over the past 5
decades; the question is _why_ this happened.

To be clear: a middle-class enthusiast really _can 't_ afford to buy the best-
selling plane of the year _new_ today, while that was a realistic option in
the 1950's.

1\. Do you not think this is bad?

2\. What do you think are the causes of that?

~~~
lisper
These are very different topics from the original one under discussion, and
much more complex. I don't know why it should matter to you what I think about
this, but since you asked, no, I don't think the increased cost of aircraft is
bad. Aviation is a very environmentally destructive pastime, so high barriers
to entry are a good thing.

As to your second question, liability concerns and government regulations
certainly add a lot to the cost of an airplane. But the flip side of that is
that modern airplanes tend to be pretty darn safe. As a pilot, I think that's
a good thing too.

------
ejlangev
> The FAA rubber-stamped those measures Friday.

Not sure what this line is supposed to mean. Is he referring to them approving
them without knowing what they are?

I'm glad for the FAA's rules. U.S. air travel is extremely safe despite
constant efforts on the part of airlines to reduce costs for themselves
without enough concern for safety. I don't think we can trust any
transportation company to value the lives of its passengers at an
appropriately high level so they need to be forced with regulation.

~~~
tomohawk
Boeing and the FAA proceed on these things as a partnership. Boeing has their
name on the line, and they have way more engineers and other technical
specialists than the FAA. In the past, Boeing has essentially written the
specs that must be adhered to by all equipment producers, and, once the FAA
approves those specs and procedures, ensures that they are followed. This book
gets into how this worked with the 747:

[https://www.amazon.com/747-Creating-Worlds-Adventures-
Aviati...](https://www.amazon.com/747-Creating-Worlds-Adventures-
Aviation/dp/0060882425)

~~~
wahern
Boeing is part of a duopoly. If a Boeing plane falls out of the sky, most
people would chalk it up to the inherent danger in air travel rather than to
fault Boeing specifically.

OTOH, part of the reason the duopoly persists is because of heavy regulation,
and specifically the strict safety regimen. From that angle Boeing has
significant economic motivation to promote costly safety margins, particularly
those which raise barriers to entry into their markets.

I understand the argument that Boeing employs countless conscientious,
professional engineers. But in 2018, with American business culture having
internalized decades of cynical, anti-social business practices, I'd be
careful about overestimating the influence of the professional class.

~~~
walrus01
> OTOH, part of the reason the duopoly persists is because of heavy regulation

Also because Boeing was ultimately more successful than the third competitor
in the market. Boeing sold many aircraft during a period in time when the
DC-10's reliability was deeply questionable in its early years, due to some
aircraft design/engineering related fatalities that killed hundreds of people.
There have been a shitload of fatal Boeing accidents including things like the
747-vs-747 crash in the canary islands, a Japanese airline 747 that flew into
a mountain, etc, but those were all caused by human factors.

There have been very few large fatality crashes that can be directly traced
back to an inherent design flaw in a Boeing plane.

~~~
dingaling
Just a couple from memory:

There were several fatal 737 accidents due to uncommanded rudder actuation.

The earlier 707 also had several cashes linked to rudder design and the UK CAA
required design changes before it was permitted on the UK register.

------
basicplus2
I wonder why one would not make the wingtips fold down..

Thus providing the opportunity to provide a permanent thrust face for the
majority of the in-flight forces and thus significantly reducing any risk of
failure.

There apears to be adequate ground clearance.

~~~
nikanj
They want to avoid the inevitable "ground crew drove a van into the wing
tip"-delays.

------
VectorLock
I wonder what the failure modes for this would be like.

Consider a Boeing 777X going along at its cruising speed and the locking
mechanism for the wing tips just disappears; primary and secondary. The
wingtip is effectively unsecured. What happens?

~~~
theothermkn
If we're going to do failure modes effects analysis, we'd need to know what
the mechanism is in order to enumerate the possible failure modes (along with
their likelihoods). For example, if the wing tips are actuated by a worm
drive, then there is no "and the locking mechanism...just disappears;" The
drive would be the locking mechanism. There are probably also suitable
bistable mechanisms that lock in the open and closed positions, requiring
actuation to unlock them.

> What happens?

In the large, I'm sure the teams of engineers at Boeing have it covered.

~~~
theoh
The conventional locking mechanism that I've seen documented is like the lock
on a bank vault: several pins, aligned with the hinge, which slide parallel to
it, locking inboard and outboard sections in place. This locking mechanism
means that the number of pins and their dimensions can be scaled to handle
arbitrary loads, and there's no single point of failure.

~~~
VectorLock
Thats what it looks like just looking at the video. Some kind of pins that
slide in when the hinge is fully down.

So one in a billion confluence of errors makes the pins disengage in the
middle of a flight. What happens?

~~~
theoh
Well, the lift on the wingtip is going to make it fold up. In the worst case,
I guess it might break off, but it's a very small part of the wing, and it
presumably doesn't contain fuel tanks. Chances of it damaging the inboard
section have to be quite small and I wouldn't be surprised if the hinge is
designed to cope with the forces involved.

For comparison, see these stories of aircraft flying safely with a much larger
wing area unintentionally folded: [https://theaviationist.com/2014/02/19/us-
navy-fighters-folde...](https://theaviationist.com/2014/02/19/us-navy-
fighters-folded-wings/)

~~~
NickNameNick
It might not even fold up. The wingtip probably incorporates some amount of
wash-out (reduced or even negative angle of attack, as compared with the wing
root) There might not be much or any upward force on it. Depending on how the
actuators work, they may be strong enough to hold the wingtip in place without
the locking mechanism.

~~~
rlpb
If there's little or no upward force on it, they might as well not have the
wingtips since they wouldn't be generating lift!

(devices such as winglets excepted; I don't think that applies here)

~~~
AceyMan
> [...] except for devices such as winglets

You answered your own question and didn't know it.

If the additional width added here has no net lift benefit but served as
winglets do to reduce induced drag from the 'mixing boundary' but even more
effectively – since the outward moving airmass doesn't have to accelerate
(read: change direction) when it hits the base of the winglet, but instead
gets to continue smoothly migrating to the tip – I can absolutely see how that
would pay off in efficiency gains.

Wings can be designed to have nearly arbitrary amounts of lift: reducing drag
for a _given amount_ of lift is the secret sauce, which could very well be
what this design achieves.

(me: FAA Licensed Dispatcher)

~~~
theothermkn
Licensed to dispatch planes or not, everything you've said about fluid
dynamics is wrong. You first seem to have confused "winglets" with "vortex
generators." I think. The only winglike thing that messes with the viscous
boundary layer is a VG. Second, winglets have nothing to do with a "mixing
boundary;" They do what they do, even in completely inviscid flow, where there
is no boundary layer. Third, whether an air mass has to "accelerate" has
nothing to do with efficiency. For example, air is adiabatically compressed as
it meets the stagnation point on a wing, or en masse as it enters a subsonic
diffuser (jet intake). The former is a consequence of fluid flow in general,
and the latter is by design. Both are completely isentropic and lead to no
total pressure losses in the flow.

Finally, it's meaningless to say that wings "can be designed to
have...arbitrary amounts of lift," and plainly incorrect to say that drag is
the "secret sauce." (Aeroelastic flutter? Wing mass? Control moments? Moment
coefficients?) Reducing induced drag is done in exactly two ways. You either
increase the span or put a winglet on so you can _effectively_ increase the
span while still being able to park the plane.

Nobody thinks they can do brain surgery, but everybody is a fluid dynamicist.

~~~
theoh
This reply is so gratuitous.

It would have been enough to say that wing extensions in general (winglets and
the 777x ones included) serve to improve the overall efficiency/performance of
the wing (so they might not be generating any lift at all, if it's even
possible to analyze them in isolation).

It's fine to make the point that we're all unqualified to discuss this because
we aren't fluid dynamicists. But dumping a load of technical language on us
that you don't expect us to understand is a rude, non-productive, and self-
aggrandizing way to do that.

~~~
AceyMan
I sought only to say how the upside could be something other than lift
increase (in the absence of any white papers from Boeing or the like) and
provided some loosely framed concepts that support that possibility.

I would address the GPs nit-picky points, but the tone is so snarky it's not
worth my effort. I may not be a fluid dynamicist, but neither am I a pedantic
putz. (subtext: chill out, dude.)

~~~
theoh
To amplify the sentiment a little bit: the guy who invented winglets did so
based on physical intuition, not calculation.

[https://en.wikipedia.org/wiki/Richard_T._Whitcomb](https://en.wikipedia.org/wiki/Richard_T._Whitcomb)

He was such an intuitionist that AFAICS he apparently spent some of his last
years on perpetual motion machines (i.e. some kind of quantum zero-point
energy device.)

The idea that it's not OK to have spirited discussions about this, that the
science should dictate who is right and who is wrong, is just inadequate to
the problem. The design space for aircraft is huge, and almost any conceivable
practical technique or configuration is going to be conventional, based on
experience.

------
mrfusion
I thought a wider wings would cause more drag? What am I missing?

~~~
kgilpin
You’ll be interested to read about aspect ratio:
[https://en.wikipedia.org/wiki/Aspect_ratio_(aeronautics)](https://en.wikipedia.org/wiki/Aspect_ratio_\(aeronautics\))

As the ratio of the span to the chord increases, the ratio of lift to drag
increases as well.

The drag of an object in the sense of forcing its way through the air (eg a
semi truck on the highway) is important, but for airplanes there is also a
very important phenomenon of drag due to lift (“induced drag”). It’s kind of
non-intuitive. But if you’ve ever seen those strong vortices coming off a
wingtip, you’re seeing induced drag. Think of the energy creating this:
[https://youtu.be/uXrnGiIMGLs](https://youtu.be/uXrnGiIMGLs)

It’s energy created by propulsion but turned uselessly into spinning air.

~~~
phumbe
You beat me by two minutes on the aspect ratio bit :)

Here's another good video showing wingtip vortices:
[https://www.instagram.com/p/BhzCLgFnVzL/?hl=en&taken-
by=edse...](https://www.instagram.com/p/BhzCLgFnVzL/?hl=en&taken-by=edseguin)

Not sure what you mean by "energy created by propulsion." The vortices result
from low pressure on top and high pressure below making the air want to curl
around. That imparts downwash on the wing, reducing its effectiveness.

~~~
kgilpin
I mean that the airplane’s propulsion system is ultimately the power source
behind those vortices, by forcing the wing through the stationary air.

------
exabrial
Sort of off topic, but sort of related too. How do you differentiate between
the types of planes Boeing makes? I know the 737, 747, 757, 777, and 787 are
all different but never really understood the meaning behind the numbers. I
know certain pilots can fly certain ones, but I've never gotten the
similarities between the designs and why that is.

------
avar
"The FAA also wanted assurances that there was no way the tips would rotate
during flight".

Does "no way" include the pilot deciding they should? If so this goes against
tho grain of the philosophy that the pilot should be in full control of the
plane. Interesting that they made an exception for this.

~~~
raverbashing
Usually yes.

> If so this goes against tho grain of the philosophy that the pilot should be
> in full control of the plane.

Clearly not. Pilots are usually prevented from destructive actions unless
there's a good reason for it or a technical impossibility (and for a large
object flying at a large speed, there are several ways they can do something
wrong)

If there's no technical reason why they should be allowed to unlock the
wingtips in flight, they will be prevented from that.

------
blackrock
To be honest, all these advancements in plane efficiency and design, is
irrelevant to me, as a passenger.

Why? Because the airlines will continue to cram you like a sardine in a can,
and will give you barely any sitting space on the plane.

Unless of course, you pay for it, to fly first class, or business class.

And to the capitalists, then this is perfect. It's exactly what a market
economy system is all about. You as the consumer, get what you pay for.

What is troubling is flying coach on a long haul international flight, that
lasts for over 10 hours. There just isn't any room to move around in your
seat. Sleeping during the plane is uncomfortable, if can even do so. And good
luck if you end up sitting in the middle. Nobody wants to sit in the middle.

If there is one thing that the FAA should regulate, it is the minimum space
allotted to flying coach on a flight. Give us back some human decency please.

------
Bromskloss
What does it actually take to get a thing allowed? What are the specific
requirements?

------
amelius
> some plane crashes occurred after pilots did not secure flaps on wings
> before takeoff. The FAA required Boeing to have several warning systems to
> make sure pilots won't attempt a takeoff before the wingtips are locked in
> the correct position.

And Boeing couldn't imagine that might be a good idea in the first place?

~~~
mrfusion
Shouldn’t they automatically lock? In what scenario do you want wings down and
unlocked?

~~~
annerajb
I guess it's hard to awnsers have we landed and should we move the wingtips to
locked positions? Airplanes afaik have no state machine that says taking off
landing taxiing. They may be able to detect it by reading all different
systems example landing gear extended altitute from ground radar over 4 feet
landing wheel moving etc. But I assume it's too many variables?

------
namirez
The correct term for these is winglet, which is a special kind of wingtip
device. There are other wingtip devices too. For example A380 has wingtip
fences.

~~~
NickNameNick
These are not winglets.

Winglets are fixed. These are new longer wings, which would make the aircraft
too wide to use existing terminals, except that Boeing have built the wingtips
to fold up while taxying and at the gate. In flight they are extended straight
out as extensions of the wings.

Winglets are cool, but a longer, straight wing can achieve the same effect
more efficiently by giving the wingtips washout (negative angle of attack).

~~~
namirez
My bad! Thanks for the correction!

