OA940 wrote:

windows on planes today are much larger than they used to be

Offhand guess: all the prop airliners had windows larger than today's airliners. (Just not so many of them.)

The DC-6 and 7 as well as the constellation were all pressurized. The DC-4 had that capability, but the C-54 which was the cargo version of the DC-4 was not pressurized.

As to the F-117, the computer software at the time could not handle smooth shapes, which was the reason for the facets. It also had radar absorbing material. Now the software is much more powerful and allows for smoother curved surfaces.

I don`t think that tube with wings is the most efficient design because of physics. Have a look at the Piaggio P180. I think that`s one of the most beautiful and fascinating airliners around.

Regarding efficiency, its way ahead of it`s tube with wings competitors. The variable lifting body will create lift without aerodynamical penalties, so it needs a smaller wing. Pusher engines are also more effective, at least for props.

But the downsides of not using a cylindical tube are massive. Every part of the body is unique, so the tool costs are way higher. Going non-circular is also challenge regarding pressure loads. And it continues with the interior. As you can use the same overhead bins, floor elements, windows frames, containers etc. throughout a cylindrical body reducing partcounts and tools, a P180 type of aircraft would need individual bins for every position.

It`s probably also harder to fix the skin when damaged.

It has also downsides for the future development of the product. While you can easily stretch a cyinder by adding a section, stretching the P180 would ruin it`s unique aerodynnamic properties and the section would have to be a totally new shape.

So basically, if you build a A320 or 777 sized P180, it would easily beat its competitors efficiency wise. But it would be extremely expensive to develop and build. Obviously way more expensive than a 10-20% fuel reduction would justify.

Who flies Avantis as airliners? Ever heard one on take-off?

GF

GalaxyFlyer wrote:

Who flies Avantis as airliners? Ever heard one on take-off?
GF

I don`t know who operates them as airliners. But it`s wiki page says under civil use:
The Avanti is operated by charter companies and small feeder airlines, and is also used as a business aircraft.

I have not heard one take off, just saw one parked close to the fence at LGKR and it really amazed me.
Wikipedia says it is loud, but the new EVO version promises 68% noise reduction?

mxaxai wrote:

Pressurization was only really introduced en-masse when jets & turboprops allowed (and required) flight at greater speeds and altitudes. Hence why the Comet's problems were so unexpected.

Wrong. The Lockheed Constellation was pressurised, entering airline service in 1945 with TWA. Also, the DC-6 and DC-7 were pressurised, to name but three very successful aircraft that were used all over the world. None of these were jets or turboprops.

Concierge wrote:

It's well documented that the windows on the early build Comet I were indeed square. The concentration of stress at those right angles, plus poor construction led to explosive decompression and disintegration. Only the earliest series one aircraft had this fatal flaw built in. De Havilland continued building through series IV, with rounded windows. The reputation of the plane was lost, and the later aircraft met with limited success.

They are not true squares, they have rounded corners.

Also, the windows did not cause the crashes. G-ALYP had its failure origin in the aperture for a glass fibre Automatic Direction Finding (ADF) antenna on the upper fuselage. G-ALYY is unknown as the wreckage was not recovered. During the water tank testing, the failure was at the forward emergency exit.

mxaxai wrote:

Look again ...

The oval windows were only introduced after the problems with the "nearly rectangular" windows had been discovered.
Here's a detail shot of the early comet's windows: http://www.c-and-e-museum.org/marville/ ... met-62.jpg

Thanks for that - you can clearly see in your close up photo that the windows are not true squares. No square has a rounded corner, so square-ish would probably be a good way to put it. Either way, it's a moot point. While the structure here was reinforced and de Havilland chose to change the windows to ovals, the Comet 1 windows are similar enough to the ones in use today. Those today just have a larger radius in the corners.

And wiki is often wrong. It’s charter and corporate plane, not enough seats for airline use—12 at the outside. It’s a turboprop, so you’d have to get passengers to buy into that.

GF

ClassicLover wrote:

Thanks for that - you can clearly see in your close up photo that the windows are not true squares. No square has a rounded corner, so square-ish would probably be a good way to put it. Either way, it's a moot point. While the structure here was reinforced and de Havilland chose to change the windows to ovals, the Comet 1 windows are similar enough to the ones in use today. Those today just have a larger radius in the corners.

This misconception often arises. The accident report used the term "window" when refering to the ADF cutout panel, which many may not know was the source of the initial break up of Yoke Peter. Some people interpreted that incorrectly to assume it meant the passenger windows, when in fact, as you correctly state in all the investigations, it was indicated that the stress around the passenger windows was higher than de Havilland had calculated ... but not the cause if inflight break-up.

The window shape and size of the Comet I windows was about the same as the DC-4M2, DC-6, DC-7 and some versions of the Boeing 377 ... all pressurized.

Just wait for the Chinese to enter the commercial airplane construction business in a big way. I'm sure Airbus and Boeing are scared to death for that to happen.

From the first flight of the heavier than air to Saturn V with the three astronauts on board to their way to the Moon, we continue to "dribble" gravity.

Lying in an afternoon of laziness, an apple "hits" the ideas of Newton, who formulates:

“The law of universal gravitation states that every particle attracts every other particle in directely the to the product of their masses and inversely proportional to the square of the distance between their centers.”

While we dribble and not dominate gravity and its effects, it seems to me that this "formula and its respective form" (airplane) will last for a long time still from now.

And if we eventually come to dominate it, we will still have the drag, which will lead to a design that must eventually slow down its effects.

So, is a flying saucer a design to consider ???

Dieuwer wrote:

Just wait for the Chinese to enter the commercial airplane construction business in a big way. I'm sure Airbus and Boeing are scared to death for that to happen.

Boy oh Boy. Boeing and Airbus will be sorry when you can go down to Harbor Freight and buy an airliner. O.K., back on topic......

longhauler wrote:

Ziyulu wrote:

Also, the speed of air travel has not increased for over 30 years.

Boeing (for example) are leading edge when it comes to engineering technology. If airlines wanted a faster aircraft, then the airframe manufacturers would have built them. But airlines do not. And why? Because passengers will not pay for faster speed / shorter times.

What do passengers (and thus airlines) want? Cheaper seats.

My guess is that is where airframe manufacturers have shown their expertise. Look at the fuel burn seat mile cost of a 1950s 120 seat 707 and compare that to today's 400+ seat 777!

I am old enough to remember both versions of the Boeing 2707, as well as the more recent Boeing Sonic Cruiser. They just couldn't couldn't make it work.

An increase in speed does not have to be supersonic, but just below. The new large twins are being touted as being able to fly 18-20 hours, I for one would rather make a connection with time to walk around the terminal than be seated for almost a day in a cramped seat with no leg room. A faster plane would be able to fly more legs per day and cover whatever the increased cost would be. Speed should be the next upgrade in air travel and leave the 60's behind.

cheapgreek wrote:

An increase in speed does not have to be supersonic, but just below. The new large twins are being touted as being able to fly 18-20 hours, I for one would rather make a connection with time to walk around the terminal than be seated for almost a day in a cramped seat with no leg room. A faster plane would be able to fly more legs per day and cover whatever the increased cost would be. Speed should be the next upgrade in air travel and leave the 60's behind.

That's not gonna happen. Any increase in speed is going to be to the supersonic range because entering transonic speeds (mach 0.8 to 1.2) causes shockwaves to form on the airfoil causing massive drag and possible instability. No one is going to want to pay that additional cost for a 5-10% increase in speed.

Mostly certification rules and physics. Try to evacuate a flying wing in time or flying at transonic speeds.

Revelation wrote:

WIederling wrote:

Hmm. did Boeing manage to keep that research stash under wraps
or why did no other significant US manufacturer bother to use that data?

Another nefarious anti-Boeing theory posted with absolutely no evidence, sigh.

Oh, sure a nefarious _question_ it was. excuse my existence.

I think most people are are overlooking the fact that todays designs (which haven't really changed since the 707 and B-47), could look much different, but there are other reasons for keeping the general design as it is.

Some people mentioned BWBs (blended wing bodies à la B-2 bomber) or even more futuristic designs. Or designs which were tried in the fast, like engines embedded in the fuselage or wings (like in the Comet and most military fighter jets). Or tailmounted engines (as in the DC-9/MD80/727/etc.). Most of the stuff has been there already.

And the fun thing is, mandy of these designs are actually more economical than the classic "engines in pods under the wings"-design.

But why is there no change if there are more economical designs?

The simple reason IMHO is that there are three factors which keep airplane designs from evolving. One point is maintenance, the other is servicability of an aircraft on the ground and the third reason is safety.

Let's talk about Boeings BWB (Blended Wing Body) design for example...



BWB maintenance: Depending on the designs that I have seen, it's either engines on top of the tail or engines build into the tail. A maintenance nightmare. For airplanes with engines inside the horizontal stabiliser like the DC-10/MD-11/727/L1011 you at least could access this engine with specially designed platforms, which could be rolled to the side of the tailplane (but this was a problem already, especially if heavier parts had to be changed, high up in the air). Now imagine engines within the tailend of the BWB or on top of that plane. How to get to the engines? How to check them? How to change parts?

BWB servicability: The phantasy design shown on the photo above shows what? Two doors on each side, both near the forward end. For a BWB probably seating 300 - 500 passengers. The cabin of the BWB would mean nearly no windows, difficulty to provide enough doors for passengers, but also for serviving the aircraft. It's gonna be horror and would need a lot of special equipment.

BWB safety aspects: Number one problem for me would be exit door limits and distance to the exit doors. I think with the current standards (and there is no reason to lower the safety standards), it would be not possible to get a large BWB certified. Perhaps a small one, but surely not a large double-decker one. Also do you really want engines on top of a pax cabin? Or even behind the pax cabin, but still on top? Having podded engines sounds quite "safe" in comparision.

Some different cabin designs I just found on google, all come with their good share of problems:





And whatever radical design you can think of, you will also run into these or similar or even other problems. And neither Boeing, nor Airbus are dumb, but apparently the cost of producing a radical design, with all these hurdles taken into consideration, is more expensive than it does gain in efficiency. So keeping the classic design from the 40s - 60s and improving this instead as far as possible, seems to be way to go. Also for the next few decades...

Dutchy wrote:

I think the answer is a Duo-poli. A blended wing design will be around 10% more efficient, but also high risk. Neither Airbus or Boeing will dare to take this risk when they have a perfect duopoli going on. I think that is the main answer.

Some of that could be true. There really isn't anyone who can shake things up completely. And if they do, they get stamped out - or in the Bombardier case, the promising plane becomes one of the competitor products.

There just isn't any need for anyone to do anything more radical than the A320, B737, 777, 787 or A350/A380. A faster plane, no point. It's simply better just to do small refinements, nothing radical.

SEPilot wrote:

o I suspect with modern technology we could build a supersonic airliner that would carry 100 passengers from LA to Tokyo

I suspect a plane would take 250 passengers quite easily, just as AST3, Alliance and others were intended to do. We don't know what fuel usage it would have, because nobody has designed the plane, nobody has tested it. It's all guesswork.

cpd wrote:

Dutchy wrote:

I think the answer is a Duo-poli. A blended wing design will be around 10% more efficient, but also high risk. Neither Airbus or Boeing will dare to take this risk when they have a perfect duopoli going on. I think that is the main answer.

Some of that could be true. There really isn't anyone who can shake things up completely. And if they do, they get stamped out - or in the Bombardier case, the promising plane becomes one of the competitor products.

There just isn't any need for anyone to do anything more radical than the A320, B737, 777, 787 or A350/A380. A faster plane, no point. It's simply better just to do small refinements, nothing radical.

Yes, I agree for now, but with stricter environmental regulations this status quo might change.

To me, it's just that the current design of airplanes is sufficiently good enough. It probably isn't perfect, but nothing compelling enough has come along that would be worth the upheaval in airport design, logistics, passenger antipathy, etc, would bring. And because of this, the past 50+ years have seen a continuous refinement of the design, instead of a radical departure to something else. Not to mention that there is a lot of inertia to change to anything new, as it would be a massive risk on the part of whoever jumped first.

In that regard, it reminds me a bit of car engines. The internal combustion engine has worked in much the same way for over 100 years. There has been a continuous process of improvement and refinement over that time so that modern engines are far superior in efficiency and NVH than they were years ago, but the principles of their operation haven't really changed because nothing sufficiently better or viable came alonge in the meantime. However the difference in vehicle engines is that the radical departure to something else is happening right now, with the emergence of electric vehicles that are becoming acceptable substitutes.

MileHFL400 wrote:

I suppose I’m asking why commercial aircraft don’t look like spaceships or something else despite 60 or 70 years of technological advancement?

Well it's hardly as if spaceships changed in those 60-70 years either. The 2 exceptions were space shuttles that looked rather much like the conventional aircraft we are so used to.
Superficially, ship design hasn't changed much either. Neither have trains, aerodynamic multiple-unit high-speed trains came into existence already in the 1930s.

Dutchy wrote:

I think the answer is a Duo-poli. A blended wing design will be around 10% more efficient, but also high risk.

A blended wing design would also have a horrible CASM. Think of it like the very short proposed 777-100 vs the stretched 777-300ER. A bit of tube in front and aft of the wing will bring down the CASM significantly.

VSMUT wrote:

Dutchy wrote:

I think the answer is a Duo-poli. A blended wing design will be around 10% more efficient, but also high risk.

A blended wing design would also have a horrible CASM. Think of it like the very short proposed 777-100 vs the stretched 777-300ER. A bit of tube in front and aft of the wing will bring down the CASM significantly.

I do not understand, Cost per Available Seat Mile should come down with a blended wing, not up. The tube doesn't do anything for lift, with a blended wing it helps so it should be more efficient in terms of CASM.

Dutchy wrote:

I do not understand, Cost per Available Seat Mile should come down with a blended wing, not up. The tube doesn't do anything for lift, with a blended wing it helps so it should be more efficient in terms of CASM.

Come down vs existing designs, yes. But it would be higher than for a blended-wing design with a stretched fuselage.

The tube barely weighs anything. At very little cost, you can increase the passenger capacity by, say, 100 passengers. Thats why the 777-300ER sells better than the 777-200LR. The -300 is heavier, but the higher payload offsets that slight penalty. The same principle will apply to a BWB design.

BTW, the tube does contribute slightly to the lift, even if it's a miniscule amount.

There are other factors to take into account too. A BWB design would require an extremely thick wing, and the chord would be extreme. These aren't exactly positive attributes for an airliner. It would result in much drag, among other items. It would also be impractical for regional-jet and A320/737 sized planes. The wing would have to be thick enough for a person to stand up inside, and have a cargo-bay in the belly.
Latest design is focusing on thin wings with a narrow chord and great aspect ration, much like a glider. Airbus has been testing this with the A340-demonstrator. The Irkut MC-21 has taken a step in this direction.

VSMUT wrote:

Dutchy wrote:

I do not understand, Cost per Available Seat Mile should come down with a blended wing, not up. The tube doesn't do anything for lift, with a blended wing it helps so it should be more efficient in terms of CASM.

Come down vs existing designs, yes. But it would be higher than for a blended-wing design with a stretched fuselage.

The tube barely weighs anything. At very little cost, you can increase the passenger capacity by, say, 100 passengers. Thats why the 777-300ER sells better than the 777-200LR. The -300 is heavier, but the higher payload offsets that slight penalty. The same principle will apply to a BWB design.

BTW, the tube does contribute slightly to the lift, even if it's a miniscule amount.

There are other factors to take into account too. A BWB design would require an extremely thick wing, and the chord would be extreme. These aren't exactly positive attributes for an airliner. It would result in much drag, among other items. It would also be impractical for regional-jet and A320/737 sized planes. The wing would have to be thick enough for a person to stand up inside, and have a cargo-bay in the belly.
Latest design is focusing on thin wings with a narrow chord and great aspect ration, much like a glider. Airbus has been testing this with the A340-demonstrator.

Interesting stuff, thanks. I can't oversee all the consequences, I am not an aircraft designer.

Perhaps the real answer to the starter question is that in fact aircraft desist has changed if fact changeda great deal.The difference being whether is is instantly visual or at a deeper engineering level.
Of course it's nice to flick through a colour coffee table book of aircaft of the 50's and 60's and look at the extraordinary visual differences that were being considered.But today one just has to enjoy all the subtle changes.
Today's contrarotaing engine core running at temp's and pressures that would melt metal,using ceramic blisks.Or extraordinary planetary gearboxes slowing down huge composite fan blades shaped using the most powerful computers.Just amazing.I wonder how today's geared fan engine compares yesterdays turbojet in terms of fuel consumption per pound of thrust.
The wing is the same.Todays ( and tomorrow's -even a laminar flow wing looks similar) wings may 'look' roughly the same as something from the 1960's but they are as different as chalk and cheese in what they are capable of and the efficiencies they are capable of.
One just has to enjoy the subtleties rather than the big picture.
Having said that.In supersonics,take a look at Aerion,or in electric hybrid aircaft-the designs here are really quite radical.So if you enjoy really clean sheet designs,these are the areas to look at ( or military/stealth of course).

cpd wrote:

SEPilot wrote:

o I suspect with modern technology we could build a supersonic airliner that would carry 100 passengers from LA to Tokyo

I suspect a plane would take 250 passengers quite easily, just as AST3, Alliance and others were intended to do. We don't know what fuel usage it would have, because nobody has designed the plane, nobody has tested it. It's all guesswork.

The physics has not changed. The Concorde burned as much fuel carrying 100 passengers from New York to Paris as a fully loaded 747 flying its longest range. A new SST will have the same load/range/fuel consumption relationship with modern airliners.

...and because - as in nature, architecture, design etc.:

'Form follows function.'

I’m asking why commercial aircraft don’t look like spaceships

Commercial aircraft that look like the concept drawings of spaceplanes from the 1950s and 1960s would by design travel at very high speeds - up to hypersonic - since those go-go years of technological optimism it has been realized how much environmental damage is done by objects moving through the atmosphere at those speeds and their engines, and determined such damage is not acceptable. (not to mention the cost which increases as the cube of speed)

What is the expected cruise speed of a BWB?
Should be a PITA to design the profile such that transonic drag is minimized.
( i.e. minimum airflow overspeed across the lifting surfaces.)

Everyone should read R.E.G. Davies “Supersonic Nonsense” for details on why it doesn’t work on the schedules and economics

neutrino wrote:

MileHFL400 wrote:

Hello,
...why commercial aircraft don’t look like spaceships........

Because they are airplanes, NOT spaceships.

Anyway, what spaceships are you referring to?
The fictional ones like the Eagle Transporter, NCC-1701 Enterprise, Millennium Falcon, Imperial Star Destroyer, MC75 Profundity and legions of other exotic not-grounded-in-physics products of imaginative minds in the entertainment industry?
In our Earth reality, the manned (limited) space-going vessels so far are nothing like that. Except for the Space Shuttle, they are generally just constricted capsules carrying about 3 persons. Yes, we have Elon Musk's proposed BFR but when is that going to happen...if ever, in our lifetime?

Strange that you start with the Eagle, since that is one of the very few that seems pretty grounded in engineering reality. I always thought that one was based on quite practical and feasible considerations for the mission it was supposed to fulfil.

WIederling wrote:

What is the expected cruise speed of a BWB?
Should be a PITA to design the profile such that transonic drag is minimized.
( i.e. minimum airflow overspeed across the lifting surfaces.)

It will be in the same range as present commercial transports. The rise in drag as you approach the speed of sound cannot be avoided, and that is what limits their speed. Boeing tried to go just a bit faster with their Sonic Cruiser, increasing efficiency to get more speed with the same fuel consumption, but found that the airliners preferred to just gain the efficiency and keep the same speed. So the Sonic Cruiser became the 787. And it will be the same with the BWB when and if it appears.

parapente wrote:

The only downside to the existing design ( tube and wing) is that the tube is ( v low drag)but deadweight.Now even that has been addressed by Boeing with the lightweight spun carbon tube.Its a very good compromise.Therefore v unlikely to change.

Without wanting to start a flame war, I want to point out that the line about the "spun tube" addressing "deadweight" is nonsense.

MileHFL400 wrote:

OA940 wrote:

Sidenote - since enough people have answered this already - but windows on planes today are much larger than they used to be, and will only get bigger with planes like the 777X coming around. As to why they can't be train-size, I'm not an expert at this, but I think the early Comets may be a good enough reason.

Wasn’t the comet window issue more to do with shape than size?

Indeed - stress concentration at the (rounded) corners of rectangular windows.

Just to quickly kill another myth (like that the 747 was "originally" a freighter design for the military bid), the first Comet crashes were *not* actually due to cracks at the windows, the cracks were in square instrumentation ports in the top of the fuselage! The intensive post-crash R&D to identify the issue led to the discovery of little-understood metal fatigue effects and *that* led to stress-reducing measures including the rounder windows found in all metal aircraft designed since then...

Edit: I see that the correct cause was covered later in the thread - I went through all of page 1 before replying, so of course it was discussed here on page 2.

may I ask also, why plane engines are still huge metal fans burning some sort of petrol?
I do not think that these sort of innovations come in the near future, but keep in mind that the Phoenix first flight is only 45 years far

o0OOO0oChris wrote:

I don`t think that tube with wings is the most efficient design because of physics. Have a look at the Piaggio P180. I think that`s one of the most beautiful and fascinating airliners around.

Regarding efficiency, its way ahead of it`s tube with wings competitors. The variable lifting body will create lift without aerodynamical penalties, so it needs a smaller wing. Pusher engines are also more effective, at least for props.

But the downsides of not using a cylindical tube are massive. Every part of the body is unique, so the tool costs are way higher. Going non-circular is also challenge regarding pressure loads. And it continues with the interior. As you can use the same overhead bins, floor elements, windows frames, containers etc. throughout a cylindrical body reducing partcounts and tools, a P180 type of aircraft would need individual bins for every position.

It`s probably also harder to fix the skin when damaged.

It has also downsides for the future development of the product. While you can easily stretch a cyinder by adding a section, stretching the P180 would ruin it`s unique aerodynnamic properties and the section would have to be a totally new shape.

So basically, if you build a A320 or 777 sized P180, it would easily beat its competitors efficiency wise. But it would be extremely expensive to develop and build. Obviously way more expensive than a 10-20% fuel reduction would justify.

The P.180 is still a tube with wings. The position of the wings compared to the tube is not usual, but it's still very classical in general shape; somehow similar to the Beachcraft Starship.

Res even faster planes: It likely will always be cheaper and more profitable to give a high paying passenger a more roomy and comfortable accommodation than flying twice as fast. The Concorde was, as I recall, fairly tight seating. Today's business class, while expensive, is extra-ordinarily comfortable. I have a friend who takes several trips a year and is accustomed to waking up half way round the world awake and ready to go.

And wings, you might compare the changes with windows. An old window was something the local glass cutter put in the wooden frame a carpenter made (and for fun I have done a few). Now a window is a system. You tell the manufacturer the exact size of the hole, and a triple pane, multiple metallic coats, inert gas sealed, and soon to have electronic capabilities to reflect or absorb heat, change colors and shading. It is a system, not a piece of glass.

The B-47 does have the shape, but needed at least two extra low tech engines (maybe even rocket boosts) to get off the ground. A modern wing has about as many moving parts as a hummingbird. . It will be efficient at getting off the ground, climbing, cruising, and gliding back to the ground. And it holds a shed-load of fuel to boot.

WayexTDI wrote:

The P.180 is still a tube with wings. The position of the wings compared to the tube is not usual, but it's still very classical in general shape; somehow similar to the Beachcraft Starship.

Both are outflow of the same period of engineering ideas and design tastes.

It's worth remembering where things stand in the history of aviation. We're looking at a mature industry today; one that has matured over the last several decades. That's the reason you don't see a lot of radical changes to the common elements. The same is true of automobiles, by the way.

Just think about how fast things change: humans went from the very first heavier-than-air flight to breaking the sound barrier in less than 50 years. You can't sustain that pace of radical innovation because there's simply not that much left to explore.

It's also a bit of a challenge to compare the range of innovation driven by pure technical ability and innovation driven by capitalist economics. Things look a lot different when governments and militaries are pushing for maximum capabilities than when the commercial incentives are in play.

It's entirely possible that there are still some future innovations out there. Perhaps there is an engineering solution to the sonic boom problem, enabling future SSTs. Likewise, perhaps there are other innovations in electric propulsion and energy storage (incentivized by climate change, fuel costs, etc).

Personally, I think the main reason on why the design hasn't changed much OR it doesn't have much variations into the design is because of the "common goals".
Most aircraft manufacturers are making Commercial Aircraft with Fuel efficiency in mind, especially in the last few decades. Instead of revolutionized the design, they just evolutionized the older design.

There are other factors that make the design soo restricted for passengers aircraft. Airport infrastructure, productions rate, profitability, lower pricing, or commercial possibility.
Their current design are optimized for "Fuel Efficiency". Not speed or looks. That's why we ended up with the things we have today.

What would changed this is Electric aircraft. In upcoming decades, this is the most probable one right now. The fuselage would still be long and circular, but the engines and wings might be revolutionized with electric.

frmrCapCadet wrote:

Res even faster planes: It likely will always be cheaper and more profitable to give a high paying passenger a more roomy and comfortable accommodation than flying twice as fast. The Concorde was, as I recall, fairly tight seating. Today's business class, while expensive, is extra-ordinarily comfortable. I have a friend who takes several trips a year and is accustomed to waking up half way round the world awake and ready to go.

Still the essential markup over the great unwashed.

If you can't have the speed advantage you must spend your money on other visible perks.
Titanic all over again. Travel by Zeppelin and Concorde, though different timeslots show
a starker environment ... but were significantly faster. cue "visible perk"

Electric hybrid.If not sight ( although likely to have distributed thrust along the wing) -- Then - sound - or the lack there of.Imagine aircaft taking off or coming into land with hardly a murmur and zero pollution over whatever city.Now that would be change.Be there in 20 years for short regionals.Now where's that solid metal/lithium battery?

Don't reinvent the wheel. Cars still has 4 wheels in the four corners under the car and wheels are still round. Why is that?

When manufacturers have a proven design and they know they can further optimize on that design (using composite or sharklets etc), there is little incentive to spend hundreds of billions of dollars to make a completely unproven design that may or may not be a market success.
After all commercial aircraft manufacture is an expensive business, just look at how much Boeing and Airbus spend each year on R&D already and how hard it is for new comers to be competitive. They have all the incentives to play it safe and protect their profits. Normally in other industries most of the cutting edge concepts first got developed in academia and then got refined by the industry to use in actual product. But because of the significant expense involved in the design of commercial aircraft, there is almost no academic research in this discipline.

WayexTDI wrote:

o0OOO0oChris wrote:

I don`t think that tube with wings is the most efficient design because of physics. Have a look at the Piaggio P180. I think that`s one of the most beautiful and fascinating airliners around.

The P.180 is still a tube with wings.

I disagree. For me a tube is a cylinder. And that`s not wht the Avanti is. It`s body is no tube, it`s basically a wing which approximates an NACA airfoil, creating 20% of total lift. It`s a wing with wings. And what`s also very unusual is that is has 4 wings. So no, I still think it`s a very unusual aircraft that does not match most of the thread opener`s descriptions of average aircraft designs.

WayexTDI wrote:

The position of the wings compared to the tube is not usual, but it's still very classical in general shape; somehow similar to the Beachcraft Starship.

I also disagree on this one. I think the main wing is very fary back, and with it the cg.

Compare that with an ATR:

The Starship is similar and in my opinion just as unusual as the Avanti.

GalaxyFlyer wrote:

And wiki is often wrong. It’s charter and corporate plane, not enough seats for airline use—12 at the outside. It’s a turboprop, so you’d have to get passengers to buy into that.

What a pity. I would love to fly one.

I am sorry but the ability to do an electric airplane using batteries is far, far off.

The current 100 kWH Tesla battery pack weight is 1,200 pounds. That is .083 kWH/lb.
Jet A is 5.36 kwH/lb, 64 X the stored energy per pound. Even if the efficiency is a multiple of around 4 (I would guess it is 1.5 or so) that would put the range of the plane to like 5% of the same plane powered by Jet A.

It might be easier to develop a higher energy density fuel.

Also, consider all electricity is produced by nuclear, hydropower, gas turbine, coal fired boilers, windmills, and solar. If using oil based fuels to make electricity there is the loss converting the fuel to electricity, battery losses, and loss converting back. The efficiency of a gas turbine is similar to a jet engine so these 3 added losses compared to just using the turbine for propulsion probably means 25% more fuel burned.

Fuel cells are a possibility but these still do not match the turbine for efficiency, if they were they would be all over the place in the power network.

o0OOO0oChris wrote:

But the downsides of not using a cylindical tube are massive. Every part of the body is unique, so the tool costs are way higher. Going non-circular is also challenge regarding pressure loads. And it continues with the interior. As you can use the same overhead bins, floor elements, windows frames, containers etc. throughout a cylindrical body reducing partcounts and tools, a P180 type of aircraft would need individual bins for every position.

It`s probably also harder to fix the skin when damaged.

It has also downsides for the future development of the product. While you can easily stretch a cyinder by adding a section, stretching the P180 would ruin it`s unique aerodynnamic properties and the section would have to be a totally new shape.

This is one part of the story where there is some light at the end of tunnel. Additive manufacturing, aka 3D printing, may be a game changer for unique shaped parts. Maybe not exactly there yet, but we can hope. Airline having one big machine making parts on demand to specs in the file instead of a huge hangar of random parts is not an impossible scenario.

lso, the windows did not cause the crashes. G-ALYP had its failure origin in the aperture for a glass fibre Automatic Direction Finding (ADF) antenna on the upper fuselage. G-ALYY is unknown as the wreckage was not recovered. During the water tank testing, the failure was at the forward emergency exit.


Thanks for that! My interest was piqued by a not-very- good book 'Jet Age' which led met to the DH site:
http://www.dh-aircraft.co.uk/aircraft/dh106/comet1/inquiry/

]

'After the tragedies at Elba and Naples, an investigation began at the RAE, lead by its director, Sir Arnold Hall. An entire Comet was tested in a water tank by continual cycles to 1.33P. After 3,060 cycles, the fuselage failed at the corner of the forward port cabin window. This was similar to G-ALYP, except that the crack on YP had started at the ADF windows at the top of the fuselage, and continued down to the forward port window.'

Granted, It's a ridiculous number of cycles, but there are many factors that lead to the root cause of metal fatigue.

Shall we go with religion or politics next?

Slainté

And per today's headline the Piaggio is gong out of business so apparently thinking outside the box doesn't net guaranteed success.

o0OOO0oChris wrote:

WayexTDI wrote:

o0OOO0oChris wrote:

I don`t think that tube with wings is the most efficient design because of physics. Have a look at the Piaggio P180. I think that`s one of the most beautiful and fascinating airliners around.

The P.180 is still a tube with wings.

I disagree. For me a tube is a cylinder. And that`s not wht the Avanti is. It`s body is no tube, it`s basically a wing which approximates an NACA airfoil, creating 20% of total lift. It`s a wing with wings. And what`s also very unusual is that is has 4 wings. So no, I still think it`s a very unusual aircraft that does not match most of the thread opener`s descriptions of average aircraft designs.

WayexTDI wrote:

The position of the wings compared to the tube is not usual, but it's still very classical in general shape; somehow similar to the Beachcraft Starship.

I also disagree on this one. I think the main wing is very fary back, and with it the cg.

Compare that with an ATR:

The Starship is similar and in my opinion just as unusual as the Avanti.

GalaxyFlyer wrote:

And wiki is often wrong. It’s charter and corporate plane, not enough seats for airline use—12 at the outside. It’s a turboprop, so you’d have to get passengers to buy into that.

What a pity. I would love to fly one.

Buses have been around for longer than jets, and they still do not travel steady 100 mph on the highway.