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Engineers are exploring radical new designs for commercial planes

wsj.com

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Re: Engineers are exploring radical new designs for commercial planes

#101

Post by scarier »

dr_orpheus wrote: post #82
scarier wrote: post #69

Earlier quoted context omitted.

How is that a meaningful distinction from either a design or manufacturing standpoint?

Because the fuselage is pressurized. And it is convenient to have pressure vessels as cylinders for even distribution of of the pressure forces across it. Ideally you want to have it capped off with two hemispheres (think propane tank shaped) but obviously you can't do that for other reasons. So there is likely more design and manufacturing for the front and rear of the plane than the main section.

Ah, gotcha. Yeah, there’s zero chance that you can make a pressurized pancake using rib-and-stringer architecture, probably even out of unobtanium. The best candidate I can think of is making it like a submarine, although that would definitely mess with the open concept floor plan and probably impose a huge weight penalty (although it might be helpful from a fatigue life standpoint). The only other remotely viable solution I can think of is drop stitching, but that has some fairly obvious drawbacks that would probably make it impracticable.

Re: Engineers are exploring radical new designs for commercial planes

#102

Post by xhkkffbf »

The thing that shocked me about this documentary about the 747 is the claim that they went from napkin sketch to working prototype in just 20 months. Twenty months!!! The world is a different place now.

https://www.amazon.com/747-Jumbo-Revolution-Christopher-Spen...

Re: Engineers are exploring radical new designs for commercial planes

#103

Post by nunez »

hindsightbias wrote: post #76
thot_experiment wrote: post #45

Earlier quoted context omitted.

I'm not sure this tracks, I think turbulence powerful enough to cause passenger discomfort is usually so big that it affects the whole plane pretty uniformly. I think it's exceedingly unlikely that you'll spend enough time on a shear line to induce a large roll. At least it's never happened to me, but I am only a passenger.

I've been in turbulence with high roll rates and even as a pilot unbothered by moderate chop, it will cause me to sweat. I've been in the last rows of a 777 and watched the fuselage flex in chop. A blended body would be pretty rigid and have a very low wing loading because it's basically all a wing. So it would be pretty uniform. It would work if all turns were managed via controls to be a 1/4g, otherwise riding the…

can't speak to aeronautics of it, but from a pax perspective, the md80 was a fantastic jet. probably the last vestige of what flying "used to be like" since they were too old to retrofit for "efficiency". also its planform looked AMAZING; retro-futuristic even

closest modern aircraft to it is the 717/MD90, which Delta is still flying, but not for much longer iirc

Re: Engineers are exploring radical new designs for commercial planes

#104

Post by robocat »

hotpotamus wrote: post #30
AlexandrB wrote: post #7

Earlier quoted context omitted.

Yup, I've been seeing these futuristic airplane concepts for most of my life, but commercial airframes seem to be converging to be more and more similar. Unusual elements like a third engine in the tail or horizontal stabilizers mounted above the rudder have largely disappeared. Given the thin margins in air travel, I suspect this is because this design is the most successful. It might be a local minimum, but when it…

My understanding is that tri-engine jetliners were actually more to fulfill a regulation than for engineering reasons. There are regulatory limits to how far a plane is allowed to fly on one engine called ETOPS - I forget what it really stands for, but the colloquial expression is: Engines Turn Or Passengers Swim. It used to be limited to around 2 hours I believe, meaning you've got a bit of time to divert and make a…

Plus having more engines doesn’t help if failures are correlated, such as some fuel issues, or http://news.bbc.co.uk/2/hi/uk_news/magazine/8622099.stm

Re: Engineers are exploring radical new designs for commercial planes

#105

Post by [deleted] »

dr_orpheus wrote: post #82
scarier wrote: post #69

Earlier quoted context omitted.

How is that a meaningful distinction from either a design or manufacturing standpoint?

Because the fuselage is pressurized. And it is convenient to have pressure vessels as cylinders for even distribution of of the pressure forces across it. Ideally you want to have it capped off with two hemispheres (think propane tank shaped) but obviously you can't do that for other reasons. So there is likely more design and manufacturing for the front and rear of the plane than the main section.

[deleted]

Re: Engineers are exploring radical new designs for commercial planes

#106

Post by carabiner »

ozzythecat wrote: post #20
carabiner wrote: post #10

Puff piece as we head into the weekend. Not a bad summary of decades old concepts, but Boeing won't touch these things due to shareholder conservatism even though they are fundamentally better than the tube with wings. If there were a SpaceX of commercial jets, this is what they would build.

I was going to call it a puff piece, but as far as Boeing is concerned: > Boeing won't touch these things due to shareholder conservatism My spouse worked for Boeing. My son currently works for Boeing. Change is the slowest and most difficult thing to bring about at Boeing. It’s part of Boeing’s DNA.

Exactly. I worked for Boeing as an intern and the entire industry is like this. It's basically 90% of aerospace, outside of the startups, is like IBM, Oracle. These companies have extraordinary history (facilities from WW2! god damn museums with their products! rise and fall tied with global geopolitics, seeing armed security and international VIP's at the guarded entrances) but will never innovate unless put up against a wall.

At my university, wind tunnels had a black curtain that could be used to conceal the test section contents. During the Cold War, they used it to prevent casual onlookers from witnessing confidential design work for the govt.

Re: Engineers are exploring radical new designs for commercial planes

#107

Post by nunez »

lvspiff wrote: post #32
blamazon wrote: post #22

Earlier quoted context omitted.

My experience as a frequent flyer is that First Class is the most likely cabin to have all windows closed for 100% of the flight. It's baffling to me, people will even keep closed the window facing New York on the approach to LaGuardia which should be a crime. Also Boston, Salt Lake, Hawaii, and really pretty much all places except like Dallas and Cleveland types totally perplex me when the window is closed and I'm n…

This always baffles me flying out west. I mean Nebraska, Kansas, Iowa - i get it - close those windows we can sleep. But the Rockies, Mt St Helens, Mt Hood, Mt Rainier...and then you hit the mfin GRAND CANYON and you still wont open up your window?!?! people that don't open their window over the grand canyon need to be put on a list for middle seat only.

yup it's insanely annoying

i flew business to hong kong a few years ago and i couldn't put the shades up AT ALL because of people sleeping most of the flight, which sucks because from the crack I was able to see through, we passed through some incredible shit

Re: Engineers are exploring radical new designs for commercial planes

#108

Post by dublin »

VBprogrammer wrote: post #21
alexpotato wrote: post #5

Interesting historical note on the blended wing design: One of the main arguments against it was that designers weren't sure if people would be ok with sitting towards the center of the plane. The thought was that passengers wouldn't be comfortable without being able to at least see outside (even a little, looking at you 3/4/3 widebody planes). I mention this b/c there is a quote in Mary Roach's Flying to Mars. She m…

My understanding is that having to manufacture a different rib for each station along the structure is a significant challenge. It's possibly less of an issue with composites?

The expensive part of composite aerostructures isn't making them, per se, it's the molds and tooling you have to build first, and you need a lot more of those when contours are constantly changing. (This isn't new though - continously changing contours have been the norm since the first high supersonic wasp-waisted "area rule" fighters and bombers appeared in the 50s and 60s.)

That said, I was working on B-2 aerostructures in the late 80s, and I can tell you that most all the parts on that plane have no symmetry in any direction other than centerline bilateral. My group figured we could save over $10 million each on a single B2 duct, if we could change the bizarre geometry to simplify the scary complex tooling it required. That was enough potential savings to provoke a design review, but the answer came back, "Nope. It has to be that way (we presumed for stealth). Go figure out how to build it..."

Re: Engineers are exploring radical new designs for commercial planes

#109

Post by MiscCompFacts »

gauravjain13 wrote: post #48
chrisBob wrote: post #23

Earlier quoted context omitted.

The issue isn't the bank angle exactly, it is the acceleration of the roll. Pilots will need to be careful not to throw people or drinks around, but I think it would be doable.

True, but absolute bank angle would also matter (say endpoint of roll when roll acceleration is zero) because now there's a component of gravity pulling you sideways.

I wonder if this could be solved by a rotating inner cabin that always maintain perpendicular to force of gravity when the plane banks?

Re: Engineers are exploring radical new designs for commercial planes

#110

Post by vel0city »

alistairSH wrote: post #85
AnimalMuppet wrote: post #58

Earlier quoted context omitted.

Not if the pilot did it right. The net force on you should always be directly toward the floor.

Even when the plane is tipped over at 15* (or whatever their max bank angle happens to be)? The floor is no longer directly underneath you.

Underneath is a relative term.
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