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Next Major Development In Aircrafts  
User currently onlineUAEflyer From United Arab Emirates, joined Nov 2006, 1065 posts, RR: 0
Posted (4 years 10 months 3 weeks 2 days 21 hours ago) and read 4520 times:

Since aircrafts was invented, all the focus was on how far the aircraft can reach, how many passengers it can carry from point to point, how to reduce the fuel burn and many other things. But the only thing that the manufacturers are not looking at (at least to my knowledge) how high the aircrafts can reach, the maximum any aircraft (wide-body) today can reach is less than 45000 feet (excluding the Concorde).
My question is why Airbus & Boeing and others do not focus on a higher attitude where the aircrafts can use less power to fly, or any other specifications that make the aircrafts fly higher.

9 replies: All unread, jump to last
 
User currently offlineHawkerCamm From United Kingdom, joined Jul 2007, 405 posts, RR: 0
Reply 1, posted (4 years 10 months 3 weeks 2 days 15 hours ago) and read 4287 times:

There is no benefit in flying higher for the current state of the art High Bypass ratio turbofans. Current engines (and airframe combinations) sit fairly optimially around 35-40,000ft.
If as expected airliner proplusion moves towards higher/ultra high bypass ratio engines (GTF or Open Rotor) I would expect "optimial design" cruise altitudes to reduce slightly.


User currently offlineMPDPilot From United States of America, joined Jul 2006, 991 posts, RR: 0
Reply 2, posted (4 years 10 months 3 weeks 2 days 15 hours ago) and read 4256 times:

I would imagine some of it has to do with the engineering required to allow a fuselage to pressurized at that altitude. Increasing the pressure differential would require extra weight with little gain.


One mile of highway gets you one mile, one mile of runway gets you anywhere.
User currently offlineCorey07850 From United States of America, joined Feb 2004, 2527 posts, RR: 5
Reply 3, posted (4 years 10 months 3 weeks 2 days 14 hours ago) and read 4215 times:



Quoting HawkerCamm (Reply 1):
There is no benefit in flying higher for the current state of the art High Bypass ratio turbofans. Current engines (and airframe combinations) sit fairly optimially around 35-40,000ft.

No except when cruising higher you have the ability to avoid most weather and get far more direct routings as there is less traffic the higher you go


User currently offlineTdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 4, posted (4 years 10 months 3 weeks 2 days 14 hours ago) and read 4144 times:



Quoting Corey07850 (Reply 3):
No except when cruising higher you have the ability to avoid most weather

True, but that's true for most cruising altitude today. The only weather that pokes up into normal cruising altitudes is weather that goes a lot higher anyway (thunderheads).

Quoting Corey07850 (Reply 3):
get far more direct routings as there is less traffic the higher you go

That's mostly a problem in dense airspace, where you're not going to be able to be at high altitude anyway. Direct routing is one of the goals of NextGen, so this is something of an independant problem from cruise altitude.

Quoting UAEflyer (Thread starter):
But the only thing that the manufacturers are not looking at (at least to my knowledge) how high the aircrafts can reach, the maximum any aircraft (wide-body) today can reach is less than 45000 feet (excluding the Concorde).

The major reason is that they focus on what matters to their customers: range, operating economics, payload, etc. Those all go straight to their customers' bottom lines. Cruise altitude, by itself, doesn't. Airplane design is a (very) complex trade bewteen a bunch of variables. If going higher would improve the overall economics, they would do so. The fact that they don't is very strong evidence that the gains from going higher aren't countered by the other things that would get worse.

Tom.


User currently onlineUAEflyer From United Arab Emirates, joined Nov 2006, 1065 posts, RR: 0
Reply 5, posted (4 years 10 months 3 weeks 1 day 22 hours ago) and read 3697 times:



Quoting Tdscanuck (Reply 4):
The major reason is that they focus on what matters to their customers: range, operating economics, payload, etc. Those all go straight to their customers' bottom lines. Cruise altitude, by itself, doesn't. Airplane design is a (very) complex trade bewteen a bunch of variables. If going higher would improve the overall economics, they would do so. The fact that they don't is very strong evidence that the gains from going higher aren't countered by the other things that would get worse.

I agree with you that it is the customers need. But the producers didn't even try that sort of thing, many R&D results are failure , why they didn't try higher altitude.


User currently offlineKeesje From , joined Dec 1969, posts, RR:
Reply 6, posted (4 years 10 months 3 weeks 1 day 21 hours ago) and read 3391 times:

The next step seems counter rotating open rotors. Still some obstacels but few seem to doubt oil willgo sky high again & real efficient, noisier engines will become feasible.



Aircraft configurations will probably look different. Laminair wings are also a promise. A recent artist impression from http://www.nlr.nl/smartsite.dws?id=8650&l=en



User currently offlineBurkhard From Germany, joined Nov 2006, 4395 posts, RR: 2
Reply 7, posted (4 years 10 months 3 weeks 1 day 21 hours ago) and read 3179 times:

Don't go into the stratosphere. Water vapor once deposited there doesn't come down in million years. One stratospheric flight is worse for global climate than 100 below that.

User currently offlineA520 From Switzerland, joined Jun 2006, 122 posts, RR: 0
Reply 8, posted (4 years 10 months 3 weeks 1 day 20 hours ago) and read 2851 times:

The answer is also security. Flying too high means that in case of cabin depressurization, even pure oxygen at the corresponding atmospheric pressure is not enough to attain the minimum partial pressure to supplement the body in oxygen. I think the Concorde's altitude is the highest possible for that respect.

User currently offlineTdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 9, posted (4 years 10 months 3 weeks 1 day 11 hours ago) and read 2645 times:



Quoting UAEflyer (Reply 5):
But the producers didn't even try that sort of thing, many R&D results are failure , why they didn't try higher altitude.

I'm not sure why you think they didn't...all of the major OEM's have enough design experience that they've either built, or know how to build, an airplane that goes much higher. It's not like it's a technological challenge, they all know how to do it. But they also know that it's not worth doing. If you told Boeing or Airbus, "I want a subsonic airplane that cruises at 65,000 and I'm willing to pay you to develop it." they'd shrug and say, "OK." But it wouldn't be economically competitive with the planes cruising in the mid 30,000' range, so nobody asks for them to build such a thing.

Tom.


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