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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

#131

Post by mannykannot »

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.

It is called a coordinated turn and it is what one normally aspires to fly.

https://www.boldmethod.com/learn-to-fly/aerodynamics/the-aer...

A coordinated turn with 60 degrees bank should be achievable by any airworthy airplane (it requires pulling 2g), and the maximum bank angle for a steady-state coordinated turn depends on how many g you can pull before you run out of control authority, cause an accelerated stall, or reach the airframe's structural limit.

Next time you fly, get a beverage of your choice and observe how it behaves. Here's an example, courtesy of the great test pilot Bob Hoover:

https://www.youtube.com/watch?v=V9pvG_ZSnCc

Re: Engineers are exploring radical new designs for commercial planes

#132

Post by karaterobot »

> Engineers are exploring radical new designs for commercial planes that would use less energy and lower emissions. But will passengers be willing to board them?

They don't really explore the question in this subtitle very well. There's like one line late in the article about "passenger acceptability is one of the criteria built into its contest", so the short answer must be yes.

I assume the longer answer is "Yeah, of course. Passengers of commercial airlines already put up with a lot of terrifying, uncomfortable, dehumanizing things, there's no reason to suspect they'd be so spooked by airplanes that look different that they decide never to travel."

Re: Engineers are exploring radical new designs for commercial planes

#133

Post by medion »

rdtwo wrote: post #9

No they aren’t. Airplanes like boats are certified in such a way that the regulations assume that all future airplanes will look like past airplanes. As such any deviation from that standard form is super expensive because you need to have the regular create an updated set of rules. That takes years and years and tons of money/risk It may make sense from a physics point of view but not from a business view.

Same thing happens with construction planning - very hard to get anything “unusual” through planning departments if it doesn’t just conform to existing methodologies, design, and often even size. Hence why movements like the tiny house movement have such a hard time - the rules were designed when building was affordable - now it’s not.

Re: Engineers are exploring radical new designs for commercial planes

#135

Post by brokencode »

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…

Personally, the only things I care about in a plane are safety (by a wide margin), comfort, and price. I spend all my time listening to music with my eyes closed or watching movies anyway, and the window doesn’t give me much.

Maybe just put a bunch of cameras all over the exterior so the passengers can see what’s going on wherever they are sitting.

Re: Engineers are exploring radical new designs for commercial planes

#136

Post by dotnet00 »

PicassoCTs wrote: post #88

Idea: How about a blended wing aircraft - that never has to land? Fuel, Passengers, luggage and waste arrive via shuttles from the airport, while the plane circles slowly, docking in flight? Other passenger and personal on end of shift. Leave the same way, to other shuttle craft and the plane flies ever onward. Only reason to ever land is maintenance which can not be performed mid flight. In theory, a specialized shu…

It might be lighter but how would it be more economical? You'd need a fleet of transport craft just to constantly dock and undock from it and at that point you might as well just make the one plane be able to land.

Re: Engineers are exploring radical new designs for commercial planes

#137

Post by dr_orpheus »

jcampbell1 wrote: post #122
dr_orpheus wrote: post #50

Earlier quoted context omitted.

> There is some crazy public belief that it is more fuel efficient There are a number of engineers at NASA and Boeing working on the X-48 who would disagree with you on this one. The main advantage of the blended wing body is to reduce the skin friction drag [0] of the aircraft relative to the typical fuselage and wings. You have less surface area in contact with the air relative to the amount of internal volume. The…

Skin friction drag is a drop in the bucket compared to parasitic and lift induced. I’m willing to accept that a gold bullion transporter can look closer to a flying wing, but with any reasonable cargo density you are back to the standard design. Trying to intuitively explain CFD results is apparently just as hard as dispelling the Bernoulli nonsense about airfoils. I’m right and high aspect ratio wings are a harder m…

One, I'll admit I'm not an expert in this, I have an aerospace degree and took some aircraft classes but it was 90% on the space side of things. But I'm trying to be devils advocate here since its not just pop-sci articles.

> Skin friction drag is a drop in the bucket compared to parasitic and lift induced

I'm trying to rectify it with papers that say "In civil aviation, skin-friction drag accounts for around 50% of the total drag in cruise conditions" [0]

> I’m right and high aspect ratio wings are a harder materials science and design challenge than blended wings

I understand that higher aspect ratio reduces drag too and that the planes should all look like scaled up gliders with their long skinny wings. But as you said, it is harder. So is it a clear cut answer that exploring blended wing designs is a waste of time?

> Let me ask you this, why is the tail of passenger aircraft upward sloping?

To prevent tail strike during take-off and landing when you are at a high angle of attack.

[0] https://www.sciencedirect.com/science/article/pii/S037604212...

Re: Engineers are exploring radical new designs for commercial planes

#138

Post by bobthepanda »

dublin wrote: post #93
hindsightbias wrote: post #76

Earlier quoted context omitted.

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…

The DC-9 and MD-[89]X were great airplanes. One of the great tragedies of unchecked American corporate consolidation/acquisition is that Boeing was allowed to borg McDonnell-Douglas. (Although some climed the opposite was closer to the truth...) Anyway, the resulting company is too large to fail, and thus, too large to exist. We're at a point where we could really use the competition we had in aerospace companies bac…

The problem is that, what airlines want, and what regulators want, is now too expensive to independently develop and start a new competitor for, even if you are well resourced like China, Japan or Russia (which all have attempted and failed to break into international aviation sales).

A new aircraft development is a $15B+ R&D investment, for the price and fuel efficiency and safety required. McDonnell-Douglass and more recently Bombardier messed up their bets and it cost them their independent existence.

Re: Engineers are exploring radical new designs for commercial planes

#139

Post by xwdv »

nicktelford wrote: post #15
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…

A bigger problem with blended wing designs is actually for the people on the peripheral. When the plane banks, passengers further from the axis of rotation will feel a more significant change in their altitude. You literally feel like you're "falling", as the plane banks to your side. This also applies to existing aircraft, but the amount you drop/rise is limited by the your distance from the axis of rotation, which…

Does this mean if a blended wing plane banks hard and you stand up on one side of the plane you could potentially jump your way across to the other side a bit?

Re: Engineers are exploring radical new designs for commercial planes

#140

Post by hnuser123456 »

rootusrootus wrote: post #115
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.

I think that would be tough. Out in relatively empty airspace, sure, the pilot can make pretty slow turns. But major airports with multiple runways, other airports in the vicinity, military bases, etc, all put hard requirements on the flight corridor. Sometimes the pilot has no choice but to make pretty sharp turns, and that means a pretty fast roll acceleration.

How about... more rudder? Of course, more control surface area means more drag and less fuel efficiency. Wonder if a flying wing style craft that has enough rudder to match traditional cylinder fuselages bank-and-yank capabilities is still more efficient.
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