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My Idea For A New ULH Aircraft  
User currently offlinePHX787 From Japan, joined Mar 2012, 7414 posts, RR: 17
Posted (1 year 11 months 2 weeks 16 hours ago) and read 3546 times:

Let me throw some disclaimers:
I don't work for any aircraft manufacturer
My ideas are based off of tech information I learned through users on here, as well as a little bit of outside research.

Here we go:
Length- 245 Feet (comparable to a 748)
Width- 22 feet (enough for 10-12 Abreast seating in econ class)
MTOW: 945,000LBS Fully loaded*
Range- 10,000nmi

here's the thing: I'm looking for possibly having 4 engines. I know this has been controversial in the past, especially with the A340, but I'm pretty sure after a certain MTOW that more than 2 engines are needed. I'm thinking something based off of the GENx or something similar.
Within the engines, I want to see if this would work: For the main fan blades, in order to increase thrust while decreasing engine weight, using sculpted composite fans that are reinforced multiple times, hollowed out on the inside of the fans. This creates less matter in each fan, therefore decreasing the weight.

The same tech would be used for the wings: I love the idea of swept wings and raked wingtips, so I'm looking at sculpted composite wings, made as one piece, reinforced laterally along the length of the wings, and hollowed out in the middle of the wing. The wing-based fueltanks, the landing gear wheel wells, and the cowlings will be the only parts of the wing that aren't hollowed out. The raked wingtip would extend back about 5 or 6 feet behind the wing.

Similar tech used in the 350 and the 787 will be used for the fuselage. I'm thinking a circular tube design similar to the 777.

The purpose of this aircraft is this: Bridge the gaps between the 77W/A340s and the 744/748/A380. Obviously the largest operators of the 744 (BA, UA, KL, KE, etc) are going to eventually need a 744 replacement. For those who don't want the 748 or the 77W, for capacity questions, this plane would be their choice.


What do you think?

I'm looking for:
1) If this plane gets into service, how many PAX would it hold?
2) Who would operate it? (Like I said I'm thinking UA and BA would be good operators, despite UA getting the A350)
3) What could be improved to this design?
4) Can anybody whip up a composite sketch? (My art skills are horrible)


Thanks for bearing with me here
-PHX787


次は、渋谷、渋谷。出口は、右側です。電車とホームの間は広く開いておりますので、足元に注意下さい。
12 replies: All unread, jump to last
 
User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 1, posted (1 year 11 months 2 weeks 14 hours ago) and read 3497 times:

Quoting PHX787 (Thread starter):
Within the engines, I want to see if this would work: For the main fan blades, in order to increase thrust while decreasing engine weight, using sculpted composite fans that are reinforced multiple times, hollowed out on the inside of the fans. This creates less matter in each fan, therefore decreasing the weight.

That's how we build fan blades now. You only put in as much material as you need to for the load. I believe the GE90/GEnX blades might be solid but, if they are, it's because they have to be. The Trent1000 blades are definitely hollow.

Quoting PHX787 (Thread starter):
The same tech would be used for the wings: I love the idea of swept wings and raked wingtips, so I'm looking at sculpted composite wings, made as one piece, reinforced laterally along the length of the wings, and hollowed out in the middle of the wing.

That's how the 787's wing is built.

Tom.


User currently offlineDocLightning From United States of America, joined Nov 2005, 19545 posts, RR: 58
Reply 2, posted (1 year 11 months 2 weeks 13 hours ago) and read 3487 times:

Quoting tdscanuck (Reply 1):
That's how we build fan blades now. You only put in as much material as you need to for the load. I believe the GE90/GEnX blades might be solid but,

IIRC, they are hollow. They are very light, though. A kid can pick them up.

Quoting PHX787 (Thread starter):
The purpose of this aircraft is this: Bridge the gaps between the 77W/A340s and the 744/748/A380. Obviously the largest operators of the 744 (BA, UA, KL, KE, etc) are going to eventually need a 744 replacement. For those who don't want the 748 or the 77W, for capacity questions, this plane would be their choice.

I doubt that there will be much of a market for ULH aircraft ever again. The only two ULH liners ever built are the 77L and the A345. Everything else has had an endurance of 15-16 hours or less. Neither the 77L nor the A345 sold very well. A345 operators were particularly disappointed with the aircraft's efficiency. The 77L is about equivalent to the 772 in efficiency.

The reasons are two-fold. First, fuel consumption goes up at the extremes of range because fuel must be burned to carry the fuel for the long trip. In the Tech-Ops folder, someone just went through some analyses of these figures and breaking a very long trip into two segments winds up making more money (more payload, less fuel).

Second, there are very few such routes on which passengers are willing to sit for 18 hours non-stop without a break. For a very long flight, like LHR-SYD, adding two hours for a stop in DXB or BKK simply doesn't make the trip that much longer. The ULH routes flown by these aircraft (EWR-SIN) are often done in all-J configurations, and there are few city pairs that can support such a service.


User currently offlineBMI727 From United States of America, joined Feb 2009, 15735 posts, RR: 26
Reply 3, posted (1 year 11 months 2 weeks 7 hours ago) and read 3389 times:

Quoting PHX787 (Thread starter):
I know this has been controversial in the past, especially with the A340, but I'm pretty sure after a certain MTOW that more than 2 engines are needed. I'm thinking something based off of the GENx or something similar.

It's not really controversial, two engines will be more efficient than four. It's just a matter of finding engines up to the task, and if you can't, you'll need more.

Assuming that you can use a GE90 and have the same thrust to weight ratio as the A380, you could support an MTOW of nearly 2,000,000 lbs.

Quoting PHX787 (Thread starter):
Width- 22 feet (enough for 10-12 Abreast seating in econ class)

Eleven is probably the best you'll get. The FAA won't allow seats separated from an aisle by more than two seats so 3-5-3 is the best you can do. Any more than that is going to require an extra aisle, and aisles don't make money.

Quoting PHX787 (Thread starter):
MTOW: 945,000LBS Fully loaded*
Range- 10,000nmi

You don't get to specify both. You figure out how much you want to carry and how far you want to carry it and based on that and what you believe the technology can deliver you find out how much the plane has to weigh to perform the mission. Then you can figure out how much wing and thrust will be necessary using that and other performance details and things begin to fall into place.

For what it's worth, your numbers seem a bit off to me. If your plane would be smaller than a 747-8 with a composite fuselage (MTOW down) and probably carry a smaller load (down again) but use the same engine combo (no change) but fly 2,000 NM farther (MTOW way up) my guess is that you'll need a higher takeoff weight than 945,000 lbs, which is over 40,000 lbs. less than the 747-8. I haven't looked at numbers in more detail than that, but I think you're a bit low on the MTOW for what you want to do.

Flying that far is going to make your plane a tanker. Fuel is an exponential relationship: to fly farther you need more fuel. Then you need more fuel to carry the fuel. Then you need fuel to carry the fuel to carry the fuel.

Quoting PHX787 (Thread starter):
I'm thinking a circular tube design similar to the 777.

I'm thinking that's a poor idea. It's true that a circle minimizes perimeter for a given area (good for drag) but you don't need all that area. A circular cross section that wide would have a lot of wasted space in the crown and possible lower deck as well, which is weight and drag you don't need. Even Gulfstream eschewed the circular cross section for the G650. My thought would be to look at a flattened ovoid cross section from which you may be able to derive some lift. I want to say it was MIT's N+3 design that showed something like this.



Why do Aerospace Engineering students have to turn things in on time?
User currently offlineclydenairways From Ireland, joined Jan 2007, 1233 posts, RR: 0
Reply 4, posted (1 year 11 months 2 weeks 4 hours ago) and read 3350 times:

Quoting DocLightning (Reply 2):
Second, there are very few such routes on which passengers are willing to sit for 18 hours non-stop without a break. For a very long flight, like LHR-SYD, adding two hours for a stop in DXB or BKK simply doesn't make the trip that much longer. The ULH routes flown by these aircraft (EWR-SIN) are often done in all-J configurations, and there are few city pairs that can support such a service.

With both BA and QF currently withdrawing more and more flights between Europe and AUS, it looks like demand for a new ULH liner will be dead.


User currently offlineDocLightning From United States of America, joined Nov 2005, 19545 posts, RR: 58
Reply 5, posted (1 year 11 months 1 week 6 days 19 hours ago) and read 3214 times:

Quoting clydenairways (Reply 4):

With both BA and QF currently withdrawing more and more flights between Europe and AUS, it looks like demand for a new ULH liner will be dead.

Are they withdrawing, or are they just splitting the route up so that BA does LHR-BKK and QF does BKK-SYD/MEL/Etc?


User currently offlineRoseflyer From United States of America, joined Feb 2004, 9604 posts, RR: 52
Reply 6, posted (1 year 11 months 1 week 6 days 19 hours ago) and read 3205 times:

Your design sounds like an all composite 747-8 and matches it with payload and engine design. Just about everything is the same except you selecting composite over aluminum and you calling out for a single deck instead of hump.

To the airlines, it sounds exactly like the market the 747-8 is going after. It probably would have a bit lower of fuel burn but significantly higher acquisition price because of all the new design required and consequent low rate of production in that market segment.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlineStarlionblue From Greenland, joined Feb 2004, 17022 posts, RR: 67
Reply 7, posted (1 year 11 months 1 week 6 days 19 hours ago) and read 3203 times:

Quoting BMI727 (Reply 3):
Eleven is probably the best you'll get. The FAA won't allow seats separated from an aisle by more than two seats so 3-5-3 is the best you can do. Any more than that is going to require an extra aisle, and aisles don't make money.

Wouldn't you be able to do 3-6-3 then?



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineBMI727 From United States of America, joined Feb 2009, 15735 posts, RR: 26
Reply 8, posted (1 year 11 months 1 week 6 days 19 hours ago) and read 3192 times:

Quoting Starlionblue (Reply 7):
Wouldn't you be able to do 3-6-3 then?

Now that I think of it, you're right. That would be possible. Not comfortable, but possible.



Why do Aerospace Engineering students have to turn things in on time?
User currently offlineDocLightning From United States of America, joined Nov 2005, 19545 posts, RR: 58
Reply 9, posted (1 year 11 months 1 week 6 days 15 hours ago) and read 3114 times:

Quoting BMI727 (Reply 8):
Now that I think of it, you're right. That would be possible. Not comfortable, but possible.

A bigger issue is what to do about the fuselage cross-section. You are starting to get into a very squashed-oval form here and that means that there is going to be a tendency for the fuselage to circularize when pressurized. Some of the newer CFRP materials might be able to withstand, but whether that might obviate any weight advantage remains to be seen.


User currently offlinePHX787 From Japan, joined Mar 2012, 7414 posts, RR: 17
Reply 10, posted (1 year 11 months 1 week 5 days 7 hours ago) and read 2916 times:

Quoting BMI727 (Reply 3):
Eleven is probably the best you'll get. The FAA won't allow seats separated from an aisle by more than two seats so 3-5-3 is the best you can do. Any more than that is going to require an extra aisle, and aisles don't make money.

I'm thinking out of comfort I'll probably keep it 10-abreast. makes sense.

Quoting BMI727 (Reply 3):
Assuming that you can use a GE90 and have the same thrust to weight ratio as the A380, you could support an MTOW of nearly 2,000,000 lbs.

I'll ignore my previous post about MTOW.

Do you think, based off this, I'll need more than 2?

Quoting BMI727 (Reply 3):
I'm thinking that's a poor idea. It's true that a circle minimizes perimeter for a given area (good for drag) but you don't need all that area. A circular cross section that wide would have a lot of wasted space in the crown and possible lower deck as well, which is weight and drag you don't need. Even Gulfstream eschewed the circular cross section for the G650. My thought would be to look at a flattened ovoid cross section from which you may be able to derive some lift. I want to say it was MIT's N+3 design that showed something like this.

My next idea is sort-of an oval shaped fuselage, length-wise oval. I'd be sacrificing a bit of cargo space, but would that make it more convenient?

Quoting Starlionblue (Reply 7):
Wouldn't you be able to do 3-6-3 then?

Who would want to sit in the middle seats there?  



次は、渋谷、渋谷。出口は、右側です。電車とホームの間は広く開いておりますので、足元に注意下さい。
User currently offlineBMI727 From United States of America, joined Feb 2009, 15735 posts, RR: 26
Reply 11, posted (1 year 11 months 1 week 4 days 18 hours ago) and read 2802 times:

Quoting PHX787 (Reply 10):
Do you think, based off this, I'll need more than 2?

My rough calculation is what you could get if you used four GE90s. You need to remember that a four engine aircraft can have a lower thrust to weight ratio than a twin because of engine out climb requirements.

Quoting PHX787 (Reply 10):
I'd be sacrificing a bit of cargo space, but would that make it more convenient?

You probably wouldn't sacrifice cargo space, since the plane would be so large but you would need some space below that for equipment. As long as there's space for that you're alright.

The cross section is a balance between structural efficiency and aerodynamic efficiency, but even then it's not always clear cut.



Why do Aerospace Engineering students have to turn things in on time?
User currently offlinePHX787 From Japan, joined Mar 2012, 7414 posts, RR: 17
Reply 12, posted (1 year 11 months 1 week 4 days 8 hours ago) and read 2717 times:

Quoting BMI727 (Reply 11):

I appreciate all your advice!!!

Can someone rough up a sketch of what this could look like?  



次は、渋谷、渋谷。出口は、右側です。電車とホームの間は広く開いておりますので、足元に注意下さい。
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