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Comment by crazygringo | Hacker News Reader

It would make me sad to remove windows on small commuter jets, since it's so much fun looking out the window and you spend a significant proportion of the flight closer to the ground anyways, watching interesting things like cities.

But on long-haul flights like Emirates has? Only 2/10 people per row have a window seat to start with, and airlines usually require everyone to close their window shade anyways for much/most of the trip, for people who want to sleep.

Sure you lose a bit of romance, but honestly for the majority of the passengers and for most of the time there's going to be zero difference... except burning less fuel means being better for the environment and hopefully slightly cheaper tickets.

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>watching interesting things like cities.

Not only cities, watching natural formations like lakes, rivers, fields, forests, hills and mountains from above is a unique perspective (compared to seeing the same from land), and very cool too. I remember being glued to the window, for tens of minutes (at least), on a flight from Europe to the US, when passing over the Arctic (or near it, not sure, but northern seas anyway), seeing vast expanses of ice floes and blue-green water glittering in the sunshine from high above. Then passing over Goose Bay as we crossed over Canada into the US, that was great too. Miles of green meadows or grassland.

With LCD screens say on the floor you can have glass bridge flying over Alps experience for every passenger independent of seat. Add magnification and AR.

might as well just watch over google maps. It's not the same thing sadly.

I’ve had the good fortune to see auroras on two overnight flights near the North Pole. Fantastic sight. A video screen won’t do it justice.

I googled for images of aurora borealis and saw a good video, it was at a place in Scotland. But you're right that the real thing would be better.

Up here in the PNW I've seen some spectacular views of Mt Rainer, Mt St Helens and Mt Hood on approach/departure. Being up in the air lends to a great sense of scale and if you catch them during golden hour very few views compare.

I happily took window seat on 13hr direct flights for the chance of seeing them back when I traveled more often.

I was up there once. Flying back, I recognized Mt St Helens. That was an amazing feeling, and an amazing view.

Mt. Shasta and the Wallowa mountains are also great to fly over on more inland routes. SF to the East coast takes you over the high Sierra which is fun and you can get some great beta on the snow conditions in the high country.

Cool. I'll check out images of those mountains.

seeing the arctic from above was truly a treat for me as well. it's so foreign looking relative to other landmasses.

Yes, it looks like something from another planet or sci-fi, maybe :) Amazing stuff.

If it really saves 50% of the aircraft weight, it's crazy that long haul airplanes today are even allowed to have windows.

That is the biggest 'wow' in the article, and I'd really love to see a source on that... but they don't provide a source and I cannot find this info when googling. Anyone can back up that claim?

I can't believe that's possible. I really want to know where that number came from.

Maybe you could reduce the weight of just the frame of the fuselage by 50%, but I bet you'd save at most 2-3% of the total takeoff weight, once you include fuel, wings, tail, engines, gear, cabin, baggage, people, cockpit, etc.

Edited: I looked into this more deeply and found the following: https://aerospace-europe.eu/media/books/CEAS2015_211.pdf

It claims a total possible weight reduction on an A320 from 2155kg to 1560kg, or 600kg off the fuselage (plus an additional 150kg elsewhere for a total savings of 750kg). An A320 weighs 42,000kg empty and 78,000kg at takeoff. 2155kg is probably the weight of the fuselage frame sections containing the windows - makes sense that you could save 50% off that piece.

That's a reduction of 1% or so off the takeoff weight.

Also, note that cargo planes are already windowless. I couldn't find a good example of a plane that has both freight and passenger versions that are otherwise identical.

Not to mention that their projection system will bring some weight and use energy, surly offsetting gains, so that whole sentence should be stricken from the article.

Well, it's not just the added weight of windows, but, I imagine, additional reinforcements for the structure that are needed when you have windows? (IANAPE - I'm not a plane expert :) )

You are correct. There's a forged doubler that goes around the window opening to reinforce it. The DeHaviland Comet lost several airplanes due to cracks starting from the windows; Boeing was having none of that.

Which is a real shame because that plane looked gorgeous, especially with square windows.

It's always sad when physics gets in the way of aesthetics...

A fantastic video about the De Havilland Comet from one of my favorite channels: https://www.youtube.com/watch?v=v0Cg2ZeYa5E

That was more due to the shape of the windows then due to the fact that it had windows. Square holes are not a good idea in aluminum that's under tensile stress. For the same reason you end a straight cut into metal in a round hole, otherwise you'll surely end up with a stress fracture.

The square corners were indeed a problem, but round windows wasn't enough. The doubler was added.

> It claims a total possible weight reduction on an A320 from 2155kg to 1560kg...An A320 weighs 42,000kg empty

Does this seem odd? The fuselage only accounts for 5% of the empty weight of the plane. I checked your sources and that's what I see too, but it still sounds low. Where does the rest of the weight go? The engines weigh about 4600 kg total. Seats weigh 35 kg x 200 or about 7000 kg. That leaves 28,000 kg. Wings? Landing gear?

Wings can easily take up 20-30% of total plane weight. Then there's a whole flight electronics and hydraulics, other interior (like ceiling, A/C), APU, tail, landing gears, etc.

So wings could be as much as 14,000 kg (7 times the weight of the fuselage) and all those other bits total 14,000 together? I'm on a plane now and it's still hard to believe that each wing (without the engine) could be 3 times the weight of the body of the plane. But I guess it must be true. Thanks for the colour.

That is the Operating Empty Weight: https://en.wikipedia.org/wiki/Operating_empty_weight

The operating empty weight (OEW) is the sum of the manufacturer's empty weight (MEW), standard items (SI), and operator items (OI).

Basically the whole plane, interior outfit and crew needed for full operations, excluding the actual fuel and payload.

Fuel (all numbers approximate):

An A320 carries around 25,000 L of fuel.[0] Jet fuel weighs ~0.81 kg/L (it varies by temperature).[1][2]

25,000 L * 0.81 kg/L = 20,250 kg = 44,550 lbs.

[0] https://en.wikipedia.org/wiki/Airbus_A320_family

[1] https://en.wikipedia.org/wiki/Jet_fuel

[2] https://aviation.stackexchange.com/questions/48785/how-is-fu...

Surely fuel is specifically not included in the plane's "empty weight".

I misread your comment. I would expect that fuel would be excluded from 'empty weight'.

I imagine that's for the empty plane, and that passengers and luggage and fuel offset that % a fair amount.

Any chance to reduce fuel consumption is a win.

Not necessarily. Another commenter on this subthread found that the weight savings equate to 1-3% of total take off weight (fuselage, engines, fuel, people, cargo). There is a safety benefit to having windows (inspecting in-flight damage to aircraft). Is 1% weight savings enough to remove a safety feature? I don’t know the answer, but it certainly isn’t a clear-cut win.

To be perfectly honest, this number sounds speculative at best (utter nonsense at worst).

The fuselage is generally about 20-40% of the entire dry, empty weight of an aircraft (speaking strictly about large transport aircraft). So clearly seeing that kind of reduction in weight isn't really possible strictly from structurally modifying the fuselage (and even major modifications of the entire airframe). If we look at comparing planes with windows (like those operated by passenger airlines) to those without (like those operated by cargo airlines), loose estimates are less than 1% to around 1% weight savings from removing windows alone. Even if you assume massively increased returns on weight savings because of massive changes in airframe design it's probably no where near 50%...

Keep in mind, even incredibly small weight reductions mean huge savings over the lifetime of an aircraft (especially if they are also carried out over an entire fleet).

It's probably done using Hollywood accounting: 50% lighter for the specific oval region where there used to be glass. Probably only a 7% gain for the total fuselage.

Also Windows play a role in emergencies: "that sides on fire, let's open the other escape door"

> Also Windows play a role in emergencies: "that sides on fire, let's open the other escape door"

That seems extremely hypothetical and optimistic. If your large passenger plane is on fire you're probably already dead.

Windows actually are used for visual inspection in flight in a number of cases. You can actually see markings above certain rows where a pilot or a flight attendant could look out and inspect something.

I think the types of things they would be looking for are flap deployment, icing, damage to the wing, gear deployment (though there is usually a window in the floor for this), etc.

There's a great YouTube channel called Mentour Pilot that covers a lot of stuff like this, but I can't find his video that discusses visual inspections.

https://www.youtube.com/channel/UCwpHKudUkP5tNgmMdexB3ow/fea...

The emergency door exit instructions specifically mention checking for fire outside as one of the steps.

It's also one of the requirements for starts and landings, along with "make sure your seat back and folding trays are in their full upright position".

Yeah, I'm sure Emirates forget about this before considering a windowless plane. Or maybe there are other ways to check for fire?

That is correct. The existence of some windows enable passengers/personnel to check for engine or wing damage (fire, birds, flap issues etc). The idea I am guessing is to use video.

The 50% lighter just doesn't work any way you spin it. I think this is another example of the journalist not really digging and verifying statements in a subject their knowledge is lacking/non-existent. (Similar to, "wine/chocolate/smoking/x cures cancer new study shows".)

You can't just remove all the fuselage reinforcements even if you remove the windows... Still, observe as mentioned in calculations [0], even the ~1% gain is significant as it accumulates over time.

[0] https://aerospace-europe.eu/media/books/CEAS2015_211.pdf

You still see outside with the fake windows... It's just a display instead. According to The Points Guy you even get a better view.

Does the "camera" point downwards? Straight out? The available views from a window seat are pretty close to a 180 degree half sphere. That won't be possible with a screen unless there's some way to pan.

Also no rays of sunlight :-/.

If there is some way to pan, it could be better than looking out the side for most passengers, if it's super HD. It presumably won't be blocked by the wing, and could encourage carriers to put nice outward-facing views on the seatback screens for passengers in other seats.

IMO it's definitely going to be a minor downgrade to the experience, offset by lower ticket prices.

With a few cameras in strategic locations, you could build a 360 spherical view of the entire outside for passengers.

If the point of removing windows is to save weight, it doesn't make sense to add cameras, screens, cables, power distribution, etc... which all add weight.

well it does make sense...if that weight is negligible compared to the amount saved from removing the windows

I wonder what radiation insulation benefits this also provides?

This is just nonsense. A display is merely a projection. you don't have any sense of depth, you can't shift the point of view, you don't have the dynamic range or resolution of the human eye. The only way it could be better if by giving you a point of view you can't normally have like directly in front or below the plane.

true about depth, that said, recent oled 4k displays were surprisingly sharp (sic)

Also cameras stop working or get obstructed, displays stop working, power gets lost, etc... A window just works

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