Boeing's folding wingtips get the FAA green light | Hacker News Reader

Boeing's folding wingtips get the FAA green light

engadget.com

106 pointsmpweiher125 comments

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).

Put autonomous cars in the exact same conditions as all cars today rather than an easy mode Silicon Valley subset and the body count will be way higher.

I don't disagree with your sentiment about the FAA. I don't believe autonomous cars are being held to a higher standard needlessly.

How often is failure of the car itself the cause of a fatal automobile accident? Just looking at lack of seatbelt use and alcohol make up 50% of traffic fatalities. It seems that the "Human Choice" is the biggest thing to fix when it comes to auto accidents.

* https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/...

I have a relative who worked at the FHWA (Federal Highway Admin) for many years. The estimate I often heard is that improper pavement design and maintenance were a factor in 20% - 30% of fatalities (think: asphalt). That friction with your tires is all that's really keeping you on the road. Many states refused to perform testing of their pavement because (a) they would have to remediate, and (b) they would likely have to go with less politically connected companies for pavement that would work better.

According to USDOT and NHTSA human error is responsible for 94% of human fatalities involving traffic crashes (including cyclist and pedestrian deaths).

If the human drives right into a huge wheel-swallowing pothole, is that "human error" or is it "improper pavement design and maintenance"?

The human should watch out. On the other hand, the pothole should be fixed.

It is probably typical to have multiple factors, making it easy to bend the numbers to one's liking.

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

Vehicles are already regulated with regards to safety features; seat-belts, airbags, anti-lock braking systems etc. These have and do prevent many deaths and serious injuries.

But holding cars to the same mechanical rigors as airplanes would make them neigh unaffordable for most, to say nothing of yearly inspections many states have which is often considered nothing more than a government subsidy to mechanic shops. It is also entirely unnecessary, as when a car has a mechanical failure, it can just roll to a stop.

As for preventing accidents in the first place, car crashes, as with plane crashes, are caused overwhelmingly by operator error.

> But holding cars to the same mechanical rigors as airplanes would make them neigh unaffordable for most, to say nothing of yearly inspections many states have which is often considered nothing more than a government subsidy to mechanic shops. It is also entirely unnecessary, as when a car has a mechanical failure, it can just roll to a stop.

For engines, yes, but it's scary how many people don't maintain their brakes properly. Or otherwise drive vehicles that are unsafe to be on the road.

https://www.reddit.com/r/Justrolledintotheshop/

There's a reason why many states, particularly northern and road salt states, have mandatory inspections.

There's also very good reasons why state patrols and the DOT do mandatory inspections of larger cargo trucks.

Obviously a car does not need to be maintained to the same standard and expense as a light aircraft. If you fuck up your own clutch it's nobody's problem but your own wallet.

Brakes and tires are two legitimate inspection points that often get neglected by drivers. Still, brake inspections especially, are very often abused by mechanic shop and/or unreasonable regulation terms to force car owners to replace far before is actually necessary.

At least in my experience, it seems every single year the shop states they won't pass the car unless some of the brakes are replaced. I suspect in this case they are just bald-face lying, as recently I balked at yet another ~$600 maintenance charge to pass a routine inspection, took the car to a friends shop out of town, and was able to conclude that the original shop never even checked the brakes, as the wheels took _a lot_ of force to remove once the lug nuts were off.

Similarly with emissions checks. It often turns into nothing more than a yearly tax on your vehicle and does nothing to improve anyone's safety.

Some states require the testers and the repair shops to be separate businesses.

Costs less than $200 to setup an LLC around here. Not a major obstacle.

But holding cars to the same mechanical rigors as airplanes would make them neigh unaffordable for most

That's why most states have an emissions test (to address the negative externality that individual drivers don't feel a cost to emit pollutants, but society does pay that cost) and a safety test. Most states do not have a general mechanical test. (The definition of what part of 'mechanical' is also 'safety' is not a bright line, so if you're arguing the safety tests sometimes go too far, maybe that's right -- we could ask an actuary who has the data I suppose.)

Well consumer cars do not have 5 point harnesses, and most cars don't even have roll cage or roll resistant frame. We use a 3 point seat belt out of convenience, and we let people drive on freeways with said cars.

Also don't install a 5 point harness without a proper roll cage you will be asking for trouble.

Not related to autonomous vehicles, but related to the risk of death for light aircraft flight vs. NASA spacecraft human-rating...

The FAA seems to be relatively OK with the current annual fatality rate for light-sport aircraft, homebuilt experimental licensed aircraft, and light aircraft in the size range of the Cessna 172. For pilots with less than 1000 hours, flying a light single engine aircraft is a relatively dangerous activity on a per-hour basis.

If human spaceflight had the same number of annual fatalities as the current number deaths in the US 48 states while flying homebuilt/kit/light sport aircraft, both NASA and the news media would be freaking out.

NASA is requiring spacex to put the Falcon9 and Dragon2 through a very expensive and rigorous period of qualification before it can carry humans on commercial launch contracts. The likelihood that there will be a totally catastrophic disaster that the launch escape system can't recover from is low, but the standard of safety (in terms of flight-hours per human per year) seems to be much, much higher than the FAA's.

The Space Shuttle suffered 2 total losses in 135 missions. Apollo had 1 total loss from a dozen or so flights (plus several heart-stopping near misses). If privately flown Cessna 172s had that kind of fatality rate, I (and many other posters on this board) would long since be a smoking hole in the ground.

Space flight is spectacularly dangerous, and US launch vehicles have a particularly gnarly safety record. Some paranoia is probably warranted.

The space shuttle, Apollo and early Soyuz were also very different spacecraft than current designs and technology.

Challenger and Columbia were lost due to institutional ineptitude. The engineers that were the manufacturer of the SRBs on Challenger specifically warned against the cold temperatures and were overruled. People noticed the foam shedding issue with the space shuttle many years before the Columbia incident. The space shuttle was a catastrophic clusterfuck of a pork barrel political design. There was actually no launch escape system or possibility of recovery from early launch phase anomaly once the SRBs were lit, until they burned out (unlike the launch escape system on Soyuz, Apollo, Dragon2, etc).

The space shuttle had a ridiculous number of moving parts and degree of complexity compared to a Dragon2 on a Falcon9 (or a Soyuz on top of its booster)

The soviet union and russia have had zero fatalities since Soyuz 11 in 1971. I would actually venture that at this point it might be statistically safer to fly along as a passenger in a modern Soyuz mission than to fly as a second passenger in some sub-500-hour pilot's kitbuilt piper cub clone.

Granted that current Soyuz is the most reliable human-carrying spacecraft today (not that there's much competition). And granted that the Shuttle was deeply weird and a bad idea.

But Wikipedia tells me that the next Soyuz to go up will be #142, counting from Gagarin. In the hypothetical world where (say) the Mir crisis had been fatal, Soyuz would have a lifetime success rate almost exactly the same as the Shuttle's.

Even if the new ones are much better, we don't have the statistical power to say. Gimme the kitbuilt Piper any day.

Considering the Soyuz-U has over 700 launches and the R7 family has over 1000 (of which all Suyuz launch vehicles are part), only taking the manned versions is a somewhat distorted comparison (though not unfavorable in some aspects).

The Soyuz-success/failure manned rate is about the same as the space shuttle, though a bit higher but with successful escapes and launch aborts. If you start comparing casualties the space shuttle loses massively as only 4 cosmonauts have died, all in the decent stage (either crashed or died on entry) with the R7 and derivatives as launch vehicles and Suyuz or Voskhod as name.

To be fair, the total of the R7 family (which is skewed since there are way more failures in the early days than after the 1990's for all kinds of rockets) is 137 vs 1755 or about 7 % vs the 1.5% of the space shuttle.

> If human spaceflight had the same number of annual fatalities as the current number deaths in the US 48 states while flying homebuilt/kit/light sport aircraft, both NASA and the news media would be freaking out.

What a nonsensical statement. If light sport aircraft had as many fatalities as the current number of deaths in the US 48 states while driving/walking/biking, both the FAA and the news media would be freaking out.

And, as pointed out, spaceflight is actually significantly more dangerous than light sport aircraft, so I'm not so sure that the "standard of safety [...] seems to be much, much higher than the FAA's."

It's supposed to be a nonsensical statement: I guess what I was trying to say is that we have come to culturally "accept" a certain number of fatalities each year in commonplace activities, like walking down the street, using a bathtub, driving a car, etc.

These are not remarked upon outside of local news. Three people die in an experimental category airplane crash, makes the local news. If three people were to die in a spacecraft accident, national media would freak the fuck out.

> we have come to culturally "accept" a certain number of fatalities each year in commonplace activities, like walking down the street, using a bathtub, driving a car, etc.

I disagree; there are ongoing, successful efforts to make driving, walking down the street (see Vision Zero for example), and many more activities safer. We haven't accepted the risk levels at all.

> I disagree; there are ongoing, successful efforts to make driving, walking down the street (see Vision Zero for example), and many more activities safer. We haven't accepted the risk levels at all.

But the existence of awareness campaigns proves the point: Someone has to connect the dots on the statistics and then advocate to get people to care. Nobody needs to advocate for more coverage of spacefaring fatalities.

> awareness campaigns

These aren't campaigns to build awareness, but to change laws, training, etc.

> Someone has to connect the dots on the statistics and then advocate to get people to care

People need to know about something in order to care about it. I'm not sure what that means.

> Nobody needs to advocate for more coverage of spacefaring fatalities.

Right; those are sensational and get lots of coverage.

I think the FAA is more concerned with 500+ people on a high-explosive ballistic missile we call a 777 than they are the one or two people on a plane they built themselves. I'm not sure how you begin to compare the two.

I'm not comparing the two. I'm comparing 4-seat spacecraft to 4-seat aircraft in the kitbuilt/homebuilt/experimental licensed/light sport category.

I'd be curious to see some actual numbers here...

I ride motorcycles, and am personally fully aware of the fact that this mode of transport makes me to a first approximation 10 times as likely to die on the road compared to driving a car, and I'm happy to accept that risk for myself.

(Probably because I have enough hubris to believe I can make a significant difference there by being more skillful and less reckless than all those _other_ motorcycle riders - which I believe psychologists refer to as "illusory superiority"...)

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

But at what cost? Ground transportation wouldn't be very useful if we couldn't afford it

Sure, "human life is sacred" and all that but that's kind of a first world problem you don't get to care about except when you already have infrastructure that's good enough for most use cases.

>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

Design and construction of new vehicles is subject to a large and ever increasing amount of regulation. It just doesn't make the news when a FMVSS gets updated to require that brake hoses meet a later revision of some SAE spec which specifies a more rigorous QC procedure.

Regarding maintenance, some negligible fraction (I've heard 6%, "less than 1%" and 0.5%) is caused by mechanical failure. If mechanical failure caused a meaningful portion of crashes you'd see insurance companies harping on about it and offering elective inspection programs in non-inspection states.

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.

That's assuming that over those years, the market would select for safer flights and not cheaper ones at the expense of safety.

The issue is that non-commercial aircraft are being held to the same standard as a 777, not that the 777 is held to an extremely high standard. There's nothing safe about a Cessna 172, period, and it's far too expensive for them to redesign it. So it's going to continue to be a 60 year old plane with updated avionics.

> There's nothing safe about a Cessna 172

Genuine question: is the 172 really considered unsafe, googling "cessna 172 safety record" brings up a lot of articles suggesting it is as safe or safer than comparable aircraft - or are you saying that light private aircraft aren't very safe in general?

Not specific to the 172, but a sizeable part of the training when getting your license is about what do when the engine stops (gliding, finding a suitable field/road/etc.) - and if you fly long enough there's a fairly good chance you'll have to put what you learned into practise.

You do realize most airplane crashes are small planes.

And most automotive crashes are non-commercial vehicles as well.

>There's nothing safe about a Cessna 172

I assume you have nothing to do with aviation. The Cessna 172 is extremely safe. In fact I'd argue that they're safer than commercial flights, because accidents are much more survivable. Safety depends purely on the pilot and the extremely well-documented maintenance routines. All accidents I've ever heard of Cessnas are caused by pilot error with minor exceptions.

Planes crashing due to pilot error is unsafe. Cars brake themselves now, Pipers have parachutes, B777s have redundancy on redundancy. The Cessna 172 is a very old design. Surviving an accident due to going too slow to die isn't "safe".

>Cars brake themselves now

Uber clearly doesn't follow this trend. Neither does Volvo, apparently https://www.youtube.com/watch?v=_47utWAoupo

>Pipers have parachutes

Only because they're prone to a certain unrecoverable spin in some configurations. You can get a ballistic chute on a Cessna too if you like.

>The Cessna 172 is a very old design

That's because it's a great design, and one that has been tested for 50 years. I'd take it over modern ones.

>Surviving an accident due to going too slow to die isn't "safe".

It is if you don't die.

No. It's assuming that modern tech is safer and more reliable. (A debatable assumption, but also a pretty fair one.)

Anyone that's ever looked to buy private planes knows that, except very small instructional aircraft, most are 40+ years old. My father-in-law just put an offer on an 8-seater built in the 1960s. And that's pretty much just the way it is for buying airplanes. It requires old tech and frequent maintenance, but it's still cheaper than the alternative.

But the problem with that is not so much that it creates a market for old airplanes but rather that airplane certifications don’t expire – if the 50’s planes you allude to had to obey the same standards as new planes (after some grace interval of e.g. 10 years), the problem could be solved?

> But the problem with that is not so much that it creates a market for old airplanes but rather that airplane certifications don’t expire

It seems to me that the problem here is that new airplanes are cost prohibitive. Your solution to light aircraft safety is to make the majority of light aviation illegal or too expensive to function, like solving the problem of unstylish watches by outlawing anything cheaper than a Rolex.

People seem to have the impression that GA has to be safer than driving, or safer than some other benchmark, before the safety level is acceptable. I am perfectly willing to accept some risk (the raw rate of fatality per ground mile is about 20x higher for GA vs. driving) even as a passenger, and I don't see why the FAA should be in the business of determining what risk is acceptable to passengers. I think the FAA's primary responsibility should be to the broader public, who experience the same risks on the ground regardless of how much or little GA they buy, rely on, or associate with.

Some of the FARs make a lot of sense in this regard, for example the rules for single-occupant ultralight aircraft (including powered paragliders), and ideally a similarly pragmatic approach can be applied to other questions in aviation regulation.

When planes crash they might fall on houses. That seems like a good reason to me to make them a lot safer than cars.

Well, also consider that you don't make GA safer than driving by regulating it. A lot of GA can be compared with the kind of unconventional driving done on remote or logging roads. GA is pretty safe where driving is also safe.

Luckily, when cars crash (or just dride) they never hit anything like houses or people.

Oh wait ...

You say that, but the same can be said about cars - you can still drive a car from the 50's, even if it no longer meets current-day safety standards (notably, rollover protection and environmental standards). Older vehicles, be it cars or planes, will retire naturally because maintenance eventually becomes prohibitively expensive.

This ignores that, unlike cars, 1950s planes are built from scratch today.

Meet the most popular aircraft in history: https://en.wikipedia.org/wiki/Cessna_172

The only updates are new engines, the aircraft's control is not just analog, it's literally "planks moved by pulling on wires".

> Bringing a new four place plane to market has been cost prohibitive. ... the FAA loosened these rules this week

Is there any independent research that supports this? I've often heard the argument that regulations are too expensive as an excuse for lowering standards.

> 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

And costs upwards of 600 thousand new.

>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

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.

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.

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

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?

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.

While there are some mechanical failure caused crashes, aren’t the vast majority of car crashes/incidents caused by driver error?

Either drunk, speeding, not paying attention, deliberately being a bellend, etc?

If anything that just means the licensing process should be stricter - not specifically a change in the cars themselves.

With self-driving cars the car is the driver so of course it has to be more strictly controlled - it has to make decisions.

> Ironically self-driving is held to a much

Is it?

The FAA is a common source of criticism and complaint among the aviation community. It's the driving force behind the continually rising costs in general aviation. Owning a small single engine plane with a hull value of $40-50k requires a financial commitment tantamount to purchasing a second home.

But, it's good to step back and recognize every now and then that every Federal Aviation Regulation (FAR, 14 CFR) is written in blood. The FAA can be a pain to deal with sometimes but every pilot I know is very, very glad that they do what they do.

> 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.

I don't think the FAA does anything lightly when it comes to passenger air travel.

The author probably misunderstood the meaning of the phrase.

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...

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.

> 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.

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.

I've flown on more Bombardiers and Embraers than Airbuses or Boeings in the past 10 years.

Bombardier effectively went broke trying to break into the the low-end of the Boeing-Airbus market with the CSeries, no?

I found that odd because, as you say, they certainly have the expertise and track record for seemingly comparable projects. To provide evidence for the hypothesis (which is a larger theme in political economics) it would be interesting to see what the precise engineering and management hurdles were as compared to smaller aircraft, especially the marginal cost. The crux of the hypothesis would be that techniques needed to remain competitive in Boeing's market--e.g. foldable wings--would be regulated in a way that made them especially costly to develop and gain regulatory approval.

> The FAA rubber-stamped those measures Friday.

The sentence before that links to a report [1].

[1]https://s3.amazonaws.com/public-inspection.federalregister.g...

>Not sure what this line is supposed to mean.

It means the writer is ignorant of the meaning of the phrase he employed.

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.

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

I wonder if it's so they can later experiment with winglets, which would fold inwards when vertical, rather than outwards which a downward fold would mandate.

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?

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.

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.

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?

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...

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.

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)

> [...] 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)

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.

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.

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.)

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

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.

I'm sure they've covered it but I'm curious as to what exactly happens.

I am not in anyway an aerospace engineer, but from the bits I do know about airline safety, but that seems like a pretty obvious question to ask so I feel like this scenario has to have been considered.

We just had that southwest flight land with a missing engine and a hole in the side, and back in the 80s we had that hawaiian flight land safely with the roof ripped off (https://en.wikipedia.org/wiki/Aloha_Airlines_Flight_243). Modern airliners are built to fly in some pretty insane conditions.

I wouldn't want to be on the plane to find out, but my gut says you'd be fine.

It's most likely accounted for. What happens is the plane takes on additional drag with decreased fuel efficiency.

In the industry there is always a high safety factor when it comes to designing systems with human lives at risk. The same applies to something like elevators. Multiple suspension cables can snap and the power can go out and the elevator can still run.

>What happens is the plane takes on additional drag with decreased fuel efficiency.

Did you just assume that? Because I'm pretty sure that a folded wingtip in flight would result in a nearly unstoppable spiral of death.

Why are you so sure? I am not sure, but my educated guess would be towards the "additional drag, possibly asymmetric" scenario.

Here's the story of the F-15 that was landed with an entire wing missing:

https://theaviationist.com/2014/09/15/f-15-lands-with-one-wi...

Parts of wings missing, engines falling off etc. happen. What wasn't survivable was the thrust reversers deploying in-flight:

https://en.wikipedia.org/wiki/Lauda_Air_Flight_004

Oh, I stand corrected: "As evidence started to point towards the thrust reversers as the cause of the accident, simulator flights were made at Gatwick Airport which appeared to show that deployment of a thrust reverser was a survivable incident. Lauda said that the thrust reverser could not be the sole cause of the crash"

The aerodynamics of fighter jets are massively different from commercial airliners.

The Lauda incident was "survivable" in the sense that they had a 3-second window to realize that the reverse thruster was deployed and take action. Without having any indication of what was happening, and with no training on what to do. So as you understand the statement was made purely to try and defend the manufacturer and airliner. Blaming pilots is a very economical way out.

>Parts of wings missing, engines falling off etc. happen.

There's only a handful of recorded engine losses (as in "ripped off the plane") of which not all were survivable. Also losing the engine is much better than damaging the wingtip. It's much closer to the body.

And please substantiate on the "Part of wings missing all time" statement, like it's a casual thing that happens all the time. Do you have any cases where a large part of the wing was ripped off? Near the end? Because I'm not aware of a single one. Wing damage happens, but aerodynamically significant wing damage is rare and lethal.

> [fighter jets different from commercial]

Yes, and an entire wing going missing is not the same as 10% of your wingspan (less in terms of area) coming unhinged.

> please substantiate on the "Part of wings missing all time"

You made up the "all the time" part and then put it in quotes as if it were a direct quote. Please don't do that.

Here's an incident with a commercial plane:

"Plane grounded after part of wing falls off mid-flight

More than 60 passengers had to be flown back to London City Airport after part of the plane's wing fell off shortly after it took off"

https://www.telegraph.co.uk/finance/newsbysector/transport/1...

Anyway, I am not saying it's a slam-dunk, or that it is a trivial occurrence. I am saying that these things have happened and therefore it is not an obviously and categorically non-survivable event, as you claim without any supporting evidence other than that it's obvious to you.

UPDATE: Here's another one

"Delta Plane Loses Part of Its Wing"

https://abcnews.go.com/US/delta-plane-loses-part-of-wing-mid...

And then there's this quora answer (it's about 50% the wing, not <10%):

https://www.quora.com/Can-a-passenger-plane-fly-if-it-loses-...

Includes a reference to a 707 that lost 25 feet of wing and landed safely:

http://www.airplanemart.com/Aircraft-Accident-and-Incident-R...

And another of an Airbus surviving a missile strike on its wing over Bagdad:

https://en.wikipedia.org/wiki/2003_Baghdad_DHL_attempted_sho...

Ok, I'm done using up my energy and time, since you obviously don't know shit about aviation, and don't care to learn, just to pretend-win an argument. Did you even read your articles? A small portion of aluminum skin on the upper part of the wing does not constitute aerodynamic failure, neither does a small portion of ripped-off aileron gliding parallel to wind flow.

The only significant accident was the 707, which was on a 4-engine plane, in the 60s, and was dubbed a miracle. If this happened on a 2-engine plane they'd all be dead.

So please stop wasting my time and go play-pretend to be a presudoacademic specialist on reddit. You'll fit right in.

I am a pilot.

So am I. I hope you're not flying commercial.

Folded wingtips look awfully similar to the winglets you see on modern jets and they fly fine!

"Winglets, as the name applies, are miniature wings, and as such they generate their own tip vortices that degrade their performance.

Winglets reduce drag, but they also generate lift at the tip, increasing the bending moment at the wing root and requiring the structure to be beefed up, adding weight."

Folded wingtips don't produce a smooth surface so my intuition would be that it would increase drag.

Nothing major will happen. If an aircraft loses one wingtip, the aerodynamic drag increases slightly (called the induced drag) which in turn causes a small moment about the vertical axis (yaw moment). The moment can be compensated by applying extra rudder.

The same could be said for any of the movable control surfaces, e.g. the flaps, ailerons, landing gear, rudder etc.

The answer being that these things are tested to destruction and procedures and failsafes put in place when necessary.

Edit: For the wingtips specifically I'd imagine not a lot of difference at all control-wise, just a loss of efficiency.

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

The shape probably comes into it - this wingtip sweeps upward at the end, so it can shed the vortex smoothly. Much like the wingtip airfoils you see on other current planes.

You’ll be interested to read about aspect ratio: 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

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

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...

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.

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

Wing efficiency increases with the wing's aspect ratio, and the aspect ratio is the quotient of the span (b) squared and the area (S): b^2/S. So making the wingspan longer with relatively little increase in wing area increases efficiency.

Span is actually the governing parameter. Aspect ratio is just a convenient parameter that grows with span if you conserve wing area. A wider wing with enough added planform area to have a lower aspect ratio would still outperform our theoretical shorter wing with higher aspect ratio.

As sailplane pilots point out, TINSFS (There is no substitute for span.)

By far, for wings of reasonable aspect ratio, induced drag is much larger than parasitic drag contributions for a wing. It's really only when you get down into the relatively soupy flow around hobby RC sailplanes that you're meaningfully constrained by skin friction. Let me explain.

The coefficients of lift and drag for wing sections are idealized, resulting from wind tunnel tests where the section spans the tunnel. This makes them effectively infinite in span, since there are no spanwise differences in the flow characteristics; All flow proceeds from the upstream direction, laterally parallel, over (and under) the section, and then down the end of the tunnel.

Real wings, however, are finite in length. While there are a number of ways to think about what happens at the wing tip, not the worst is to say that high pressure air from under the wing leaks onto the low pressure side above the wing. (It's an oversimplification, but it mostly works.) This finite wing effect is associated only with the tip of a long wing; Flow around sections of a wide span wing near the root behaves a lot more like ideal wing section flow than flow close to the tips.

This leakiness does a couple of bad things, and at least one not-so-horrible thing. First, it reduces the coefficient of lift for the span as compared to the wind tunnel flow. Second, it gives rise to induced drag, which is that rotationally energized flow leaving the wing tips (plus the fact that your reduced lift coefficient means you have to pitch higher, basically aiming more of your lift aft). Third, and the good(ish) bit, is that it mushes out the stall, at the expense of a lower stall angle of attack. (It's nice when stalls happen gradually, with warning, rather than suddenly.)

Those raised wing tips you see are a compromise between parking and performance. They are about 2/3 as effective as they would be if they were horizontal extensions of the wing.

Notice that I'm talking here about span, and not aspect ratio. Aspect ratio, pointedly, is not a substitute for span. If you doubled a wing's width, you would get no reduction in benefit from doubling its chord length as well, other than a possible weight penalty, or the skin friction drag to which I think you allude. As they say on Monty Python, "SPAN! SPAN! SPAN! SPAN!..."

The one exception to this is very light craft at very low wing loadings, like RC sailplanes. (So-called "floaters.") Down there, the lift, and therefore induced drag, is so low that the parasitic drag begins to dominate, and you can choose an "optimum" span for a given flight weight. I forget the paper where I saw the derivation of that.

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.

"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.

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.

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.

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

> 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?

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

It's not just about locking in-place. These warnings will almost certainly include warnings about them being up instead of down, for example.

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?

Who says that Boeing didn't plan on having warnings? That warnings are required by the FAA in the new rules created doesn't mean Boing wanted to have none, it just says the FAA wants warnings.

It says several planes crashed because of this. I assume they are talking about the same type of planes, perhaps test-models.

AFAIK, this is the first passenger plane with this feature.

Other planes with folding wings have been military, and they may have skipped the redundant locks and warning systems in favor of weight reduction.

There were civilian planes with folding wings, like the Fairchild FC-2 or the Avro Avian. The idea was to make it easier to move them by road or to store them, for instance in a small hangar in Northern Canada for the Fairchild, which was used as a bush plane.

Probably a bad assumption given that this model is not flying yet.

The FAA's approach is that any kind of problem that has been seen already needs to be investigated. Planes crashed on some other model because flaps were not locked on takeoff? That type of error goes into a checklist of things to look at. Now everything that needs to be right for takeoff needs to be locked into place!

> Probably a bad assumption given that this model is not flying yet.

I imagine it has flown, just not commercially yet.

It hasn't. Aviation is a hugely popular spectator hobby. Any time a new plane (not even a new model, just a new plane like a 737) rolls out of the factory, it makes the news in these circles. When a new model of plane (like the 777X) rolls out of the factory for the first time, it makes international, front page news. Doubly so when it actually takes it's first test flight.

We're talking about massive passenger jets that are manufactured in the middle of a major metro area in a facility where they give public tours and is watched day and night by hobby and professional photographers alike. These aren't things that they go and "test fly" in secret, even if they wanted to (which they don't, because the 777X's first flight would be such a massive PR event that they would be insane to keep it secret).

You could easily look this stuff up rather than assuming.

To date, the number of 777X aircraft built is zero. Boeing currently hopes to complete the first one late this year or early next year, and is targeting "sometime Q1 2019" for test flights.

The planes crashed because their flap settings were incorrect. Not these winglets/wingtips. Just normal, everyday flaps. And the reference is poorly worded; these haven't flown yet, and the reference is referring to other jet airliners.

There are no test models of the 777X flying yet. And the source material specifically says "flaps", which are not at all the same type of "foldable wingtip" that is being referred to. They refer to very specifically different things.

The planes they are referring to are any other passenger jet, such as Spanair 5022, that crashed due to improper flap deployment.

https://en.wikipedia.org/wiki/Spanair_Flight_5022

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.

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).

My bad! Thanks for the correction!

Reply on news.ycombinator.com