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Engineers are exploring radical new designs for commercial planes

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Re: Engineers are exploring radical new designs for commercial planes

#141

Post by pencilguin »

Airframes equipped to use LH2 will, wherever deployed, lock out competitors without, because the lower takeoff fuel weight allows for more paying cargo instead, and because hydrogen electrolysed right there at the airport should be cheaper per joule than petroleum mined, transported, refined, and transported again.

But inboard LH2 tanks seem to present a safety hazard, wings have not enough room. That seems to leave underslung nacelles. None of the concept designs illustrated have them.

Re: Engineers are exploring radical new designs for commercial planes

#142

Post by Retric »

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.

The issue isn’t the bank angle but pitch acceleration felt by the passengers when they pilot wants to bank for a turn. Which opens up several methods to compensate.

You could for example more slowly enter a higher bank angle to have an equally fast turn though passengers would feel more pressed into their seats etc.

Turbulence causing roll upsets seems like it could be a larger issue.

Re: Engineers are exploring radical new designs for commercial planes

#143

Post by Retric »

hnuser123456 wrote: post #140
rootusrootus wrote: post #115

Earlier quoted context omitted.

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.

Lateral acceleration is less pleasant for passengers. You don’t want peoples drinks to fall off their tray tables for example.

That said there is a fair about of wiggle room so I doubt it’s a significant issue in practice.

Re: Engineers are exploring radical new designs for commercial planes

#144

Post by robotresearcher »

brokencode wrote: post #135
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.

I hear you. But the first time I did a polar/Hudson Bay flight between Europe and west coast USA, I was transfixed by the view out of the window. I’m very happy to have seen that extraordinarily beautiful view.

Cameras would be some compensation, but the direct view is amazing.

Arguably not as spectacular, but I relish every city approach. The serpentine Thames as you stack over Heathrow, the mountains of Vancouver, the insane scale of Tokyo: I value fuel and cost savings, but I hope there will always be opportunities to experience these wonderful views.

Re: Engineers are exploring radical new designs for commercial planes

#145

Post by pc86 »

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.

If the turn is coordinated you can't tell the difference. I've been in small GA planes turning at 35-40 degrees and it doesn't feel like you're sliding at all, you're pulled back into your seat and "down" (relative to you) into the flooring.

Re: Engineers are exploring radical new designs for commercial planes

#146

Post by robotresearcher »

FriedPickles wrote: post #14
camillomiller wrote: post #8

Call me when they've solved seats in such planes. If you put them in a central "barrel" like in a current plane it would be a bad use of the available space. Yet you can't do otherwise. Because of the heavy banking when the plane turns, you can't seat people far away from the central axis and closer to the side edges of the V shape.

Interesting point. Cargo and fuel should be placed on the far sides. Passengers towards the center, perhaps on two levels. Routes could be adjusted to decrease typical bank angles. Makes me wonder if we'll have cargo-only planes that converge on a different optimum. In full autonomous mode, comfort is not a factor and reliability can also be relaxed. Of course, we'd lose the flexibility of being able to convert the p…

Bank accelerations must be limited, not angles. You could do a full roll without noticing if the acceleration vector pointed mostly through the plane’s floor.

Re: Engineers are exploring radical new designs for commercial planes

#147

Post by metadat »

robotresearcher wrote: post #146
FriedPickles wrote: post #14

Earlier quoted context omitted.

Interesting point. Cargo and fuel should be placed on the far sides. Passengers towards the center, perhaps on two levels. Routes could be adjusted to decrease typical bank angles. Makes me wonder if we'll have cargo-only planes that converge on a different optimum. In full autonomous mode, comfort is not a factor and reliability can also be relaxed. Of course, we'd lose the flexibility of being able to convert the p…

Bank accelerations must be limited, not angles. You could do a full roll without noticing if the acceleration vector pointed mostly through the plane’s floor.

Would this likely become a dangerous "recovery" scenario with the plane spinning around on the center axis and accelerating directly towards the ground? This sounds dangerous for any passenger aircraft.

Re: Engineers are exploring radical new designs for commercial planes

#148

Post by q-big »

moffkalast wrote: post #119
bmitc wrote: post #94

All I can think is: yea, they're called high-speed trains.

They really ought to get around to building that transatlantic track

> They really ought to get around to building that transatlantic track

In the past, concepts for a transatlantic tunnel that is used by advanced trains were conceived:

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

Re: Engineers are exploring radical new designs for commercial planes

#149

Post by majormajor »

blamazon wrote: post #22
JustSomeNobody wrote: post #19

Earlier quoted context omitted.

Anecdotally, I hate flying if I can't see out the window. Like, really really hate it.

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…

When I've flown first class frequently it was during times of my life when I was flying a lot and so had miles to burn on upgrades and such.

After the first few times - especially if you're flying the same routes over and over - I got used to it, for better or worse.

Re: Engineers are exploring radical new designs for commercial planes

#150

Post by lstodd »

dongobongo wrote: post #77
nicktelford wrote: post #15

Earlier quoted context omitted.

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…

people in the center, cargo in the peripherals

makes evacuaion harder that it has to be
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