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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

#91

Post by keepquestioning »

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.

Tell them to work for Boom Aerospace.

Re: Engineers are exploring radical new designs for commercial planes

#92

Post by jabl »

ramesh31 wrote: post #87
jabl wrote: post #84

Earlier quoted context omitted.

Horizontal stabilizers above the rudder went away with the engines mounted on the body in the back, the reason for the high tail was to keep the elevators away from the jet blast of the engines. As to why create a design like that in the first place, I don't know. My understanding is that the 'engines under the wings' layout won because with the engines in the back the fuselage needs to be stronger (and thus heavier)…

A lot of the reasoning for business/regional jets maintaining the high tail mount engine layout is FOD avoidance. Operating out of shorter runways/smaller airports this becomes an issue.

Isn't much FOD ingestion due to the wheels kicking up something? If so, mounting the engines in the back seems like a bad idea, as even if they are higher up than an under wing mounting there's a risk that the wheels might kick up some debris?

See also SAS flight 751, where ice broke off from the wings and were ingested into the engines https://en.wikipedia.org/wiki/Scandinavian_Airlines_System_F...

From a FOD perspective, in my admittedly very non-expert opinion the best location would be to have either a high mounted wing with engines in the traditional under wing position, or then engines above the wings like the Honda business jet?

Re: Engineers are exploring radical new designs for commercial planes

#93

Post by dublin »

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…

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 back in the 80s, when there were enough competitors in both military and commercial aviation for competitive pressures to keep the players working to provide innovation and value. (Rather than milking the market with intentionally poor designs a la Boeing's 737MAX.) Modern airlines have only two vendors to choose from now that Boeing and Airbus have gobbled up even their second-tier competitors.

Personally, I'd love to see what the old Convair, LTV, pre-Martin Lockheed, or pre-McDonnell Douglas might come up with in this competition...

Re: Engineers are exploring radical new designs for commercial planes

#95

Post by dublin »

amelius wrote: post #52
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…

Banking isn't a problem in practice or your coffee wouldn't stay in your cup while standing on the table.

That's called a "coordinated turn", and it's what airline pilots should be aiming at whenever possible. In a coordinated turn, "down" remains aimed at the floor, regardless of actual bank angle. There's even an instrument (the turn-and-bank indicator) designed expressly to help pilots execute coordinated turns, which are generally considered a mark of a capable pilot in any plane...

Re: Engineers are exploring radical new designs for commercial planes

#96

Post by blamazon »

anthomtb wrote: post #78
lvspiff wrote: post #32

Earlier quoted context omitted.

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.

I am regularly on flights which go over the Grand Canyon. On that flight specifically, I keep my window shade open for the sake of the folks in the middle and aisle seats. Of course, they are probably thinking "wish that view didn't have that sleeping dude in the foreground".

You're still a hero. Thank you for sleeping so I don't have to feel awkward making you think I am looking at you while looking out the window.

Re: Engineers are exploring radical new designs for commercial planes

#97

Post by [deleted] »

scarier wrote: post #26
VBprogrammer wrote: post #21

Earlier quoted context omitted.

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 differences in ribs across the span of a wing are much less of an issue than compound curvature in the wing skins—this is where composite manufacturing really shines, because you can mold them into arbitrary shapes.

[deleted]

Re: Engineers are exploring radical new designs for commercial planes

#98

Post by orangepurple »

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.

The plane turns while banking which results in a force vector mostly straight down towards the floor. If the plane did not turn while banking what you wrote is true.

The ground is whatever you accelerate towards.

Re: Engineers are exploring radical new designs for commercial planes

#99

Post by edh649 »

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.

Balanced out by the centripetal force of the plane turning!

Re: Engineers are exploring radical new designs for commercial planes

#100

Post by PicassoCTs »

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…

>This also applies to existing aircraft, but the amount you drop/rise is limited by the your distance from the axis of rotation, which is normally not very far.

When a plane is crabbing, as in coming in sideways towards the runway, when it touches down, and suddenly pivots to normal runway directions, even passengers in the rear of a normal plane, might be accelerated hard around the yaw axis.

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