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by Matt6461
Sat Jun 27, 2020 11:06 am
Forum: Civil Aviation
Topic: MC-21 Development Thread
Replies: 520
Views: 148402

Re: MC-21 Development Thread

This plane looks way better than 737 or A320. Hope the Russians can behave and let it spread its wings.

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by Matt6461
Thu Apr 30, 2020 2:57 am
Forum: Civil Aviation
Topic: The Airbus A380 Turns 15 Today (April 27)
Replies: 47
Views: 5233

Re: The Airbus A380 Turns 15 Today (April 27)

I think we will need to be confined to dreaming when it comes to any sort of clean sheet in the next five to ten years. Yep. I'm thinking of my retirement probably - easy, cheapish, comfortable flights to far-flung spots on a big VLA. I'll regale the FA's with tales of living through the COVID cris...

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by Matt6461
Wed Apr 29, 2020 8:14 am
Forum: Civil Aviation
Topic: The Airbus A380 Turns 15 Today (April 27)
Replies: 47
Views: 5233

Re: The Airbus A380 Turns 15 Today (April 27)

Matt still favored the 10+8 cross section that Airbus chose. I still feel a more appropriate cross section would be 8+6. It would get rid of the 2nd aisle upstairs so lots of weight and the longer thinner airplane would have more space for bags/cargo per pax and would be lighter overall with a pret...

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by Matt6461
Wed Mar 18, 2020 11:42 pm
Forum: Civil Aviation
Topic: MC-21 Development Thread
Replies: 520
Views: 148402

Re: MC-21 Development Thread

Found some interesting comparisons of the MC21 done by AFL against the A and B narrowbodies in their fleet. If this bird is reliable and gets a good support network it will give them a run for their money. MTOW, Seats, Avg. Fuel in kg/h, Fuel in grams per ASK https://cdn.aviaforum.ru/data/attachmen...

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by Matt6461
Sat Mar 07, 2020 2:12 pm
Forum: Civil Aviation
Topic: MC-21 Development Thread
Replies: 520
Views: 148402

Re: MC-21 Development Thread

Found some interesting comparisons of the MC21 done by AFL against the A and B narrowbodies in their fleet. If this bird is reliable and gets a good support network it will give them a run for their money. MTOW, Seats, Avg. Fuel in kg/h, Fuel in grams per ASK https://cdn.aviaforum.ru/data/attachmen...

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by Matt6461
Sat Feb 22, 2020 12:59 pm
Forum: Civil Aviation
Topic: 777X vs A350 CASM
Replies: 259
Views: 27939

Re: 777X vs A350 CASM

[*]779's Y seating is ~ 5% more space-efficient :ROFL: I mean that’s straight from the corporate communication handbook. My bank balance appears to be getting more and more ‘space efficient’ every day. Fred Sent from my iPhone using Tapatalk Spurious, childish argument. The idea that the 779 can fl...

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by Matt6461
Fri Feb 21, 2020 11:19 pm
Forum: Civil Aviation
Topic: 777X vs A350 CASM
Replies: 259
Views: 27939

Re: 777X vs A350 CASM

HeavyMetal wrote:
Multiple large, blue chip airlines use this metric [marginal capacity cost] as their primary tool for fleet comparisons and quick analyses.


Really? Do you have a cite for this? I've been trying to force this metric on A.net since ~2015 but nobody else uses it here.

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by Matt6461
Fri Feb 21, 2020 10:03 pm
Forum: Civil Aviation
Topic: 777X vs A350 CASM
Replies: 259
Views: 27939

Re: 777X vs A350 CASM

https://leehamnews.com/2018/05/17/boein ... -carriers/ Also: Per seat fuel burn: -1.5% Per seat DoC: -1.2 ~ 1.5% Aircraft trip cost: +11% Seats per aircraft: 45 (+12%) That's for a 7000+nm mission, should be close to the best case for the 779. Thanks, those are different numbers than I recall from ...

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by Matt6461
Fri Feb 21, 2020 10:07 am
Forum: Civil Aviation
Topic: 777X vs A350 CASM
Replies: 259
Views: 27939

Re: 777X vs A350 CASM

My source is Leeham's analysis (Bjorn's), which is behind a paywall and I'm no longer a subscriber. Plus the simple fact that the 777-9 has been ordered at all tells me it's more efficient than A35K. With limited exceptions, airlines don't order larger planes unless they're more efficient. I think ...

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by Matt6461
Thu Feb 20, 2020 10:28 pm
Forum: Civil Aviation
Topic: 777X vs A350 CASM
Replies: 259
Views: 27939

Re: 777X vs A350 CASM

How do you know this? I cannot find a source for such information. My source is Leeham's analysis (Bjorn's), which is behind a paywall and I'm no longer a subscriber. Plus the simple fact that the 777-9 has been ordered at all tells me it's more efficient than A35K . With limited exceptions, airlin...

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by Matt6461
Thu Feb 20, 2020 8:43 am
Forum: Civil Aviation
Topic: 777X vs A350 CASM
Replies: 259
Views: 27939

Re: 777X vs A350 CASM

779 is definitely more efficient than A35K. How do you know this? I cannot find a source for such information. My source is Leeham's analysis (Bjorn's), which is behind a paywall and I'm no longer a subscriber. Plus the simple fact that the 777-9 has been ordered at all tells me it's more efficient...

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by Matt6461
Wed Feb 19, 2020 5:10 am
Forum: Civil Aviation
Topic: 777X vs A350 CASM
Replies: 259
Views: 27939

Re: 777X vs A350 CASM

Bjorn Fehrme at Leeham posted analysis a few years ago behind the Leeham paywall. 777-9 was more efficient than A35K on both fuel and direct operating cost. He used a standard seating layout to make it an apples-apples comparison. IIRC the fuel difference was such that it would disappear absent the...

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by Matt6461
Tue Feb 18, 2020 7:05 am
Forum: Civil Aviation
Topic: 777X vs A350 CASM
Replies: 259
Views: 27939

Re: 777X vs A350 CASM

Bjorn Fehrme at Leeham posted analysis a few years ago behind the Leeham paywall. 777-9 was more efficient than A35K on both fuel and direct operating cost. He used a standard seating layout to make it an apples-apples comparison. IIRC the fuel difference was such that it would disappear absent the ...

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by Matt6461
Thu Jan 30, 2020 7:33 pm
Forum: Technical/Operations
Topic: Future VLA Market?
Replies: 91
Views: 5159

Re: Future VLA Market?

What's L/D? At cruise it should be at least 24, at max endurance or max L/D speed (slightly slower), it should be 25-26. Using 25 L/D, drag at critical case is 30.8k lbs [770,000 / 25], let's say 30k lbs given a slightly higher L/D. Sorry Matt, dragging this up but I was scanning through and this j...

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by Matt6461
Thu Jan 30, 2020 5:08 am
Forum: Civil Aviation
Topic: Boeing CEO: NMA will "start with a clean sheet of paper again"
Replies: 1642
Views: 155138

Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

FG ( https://www.flightglobal.com/air-transport/boeing-still-deciding-which-market-segment-its-next-aircraft-should-target/136438.article ) gives some interesting quotes from Calhoun regarding the decision to "reassess our commercial product development strategy to determine what family of air...

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by Matt6461
Thu Jan 30, 2020 4:44 am
Forum: Technical/Operations
Topic: Future VLA Market?
Replies: 91
Views: 5159

Re: Future VLA Market?

You need to study Part 25 and AC 25-7 to realize a quad designed that way doesn’t work. Failure of one of the big engines at V1 needs to be accounted for and that probably won’t work. You need to read the thread before assuming I didn't account for failure of one of the big engines. It's explicitly...

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by Matt6461
Tue Jan 28, 2020 9:30 pm
Forum: Technical/Operations
Topic: Future VLA Market?
Replies: 91
Views: 5159

Re: Future VLA Market?

If I'm transparently stupid you really could use a mirror. And in accordance with the forum rules, you might want to cool your jets mon frere. I've said nothing about you personally, only your argument. In fact, I've said that many very smart people made your bad argument during decades of A380 mar...

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by Matt6461
Fri Jan 24, 2020 10:44 am
Forum: Civil Aviation
Topic: Boeing CEO: NMA will "start with a clean sheet of paper again"
Replies: 1642
Views: 155138

Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

So NMA was basically a billion-dollar* A.net thread. Hope they had fun in Seattle while it lasted. *Will we get to see a write-down amount eventually? Boeing made it sound as if they were well into detailed design. So what is Boeing going to do then? Build the NSA? Does the NMA still exist? What ab...

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by Matt6461
Fri Jan 24, 2020 7:52 am
Forum: Civil Aviation
Topic: Boeing CEO: NMA will "start with a clean sheet of paper again"
Replies: 1642
Views: 155138

Re: Boeing CEO: NMA will "start with a clean sheet of paper again"

So NMA was basically a billion-dollar* A.net thread. Hope they had fun in Seattle while it lasted.

*Will we get to see a write-down amount eventually? Boeing made it sound as if they were well into detailed design.

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by Matt6461
Tue Jan 21, 2020 9:17 pm
Forum: Technical/Operations
Topic: Future VLA Market?
Replies: 91
Views: 5159

Re: Future VLA Market?

However then you have some who harp on about sticking a ge90 in the tail of a 777, asking why there's no 747-200neo and making outrageous statements. It works to dissuade those with actual interest and knowledge I don't mind people posting outrageous ideas because one has to have a certain level of...

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by Matt6461
Tue Jan 21, 2020 4:25 am
Forum: Technical/Operations
Topic: Future VLA Market?
Replies: 91
Views: 5159

Re: Future VLA Market?

OK another note on why this proposal is VLA-specific. The first and most obvious reason is that only a large plane is likely to be a quad in today's environment. The less obvious reason relates to a VLA's drag composition: A double-decker economizes on parasitic drag via having less fuselage wetted ...

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by Matt6461
Tue Jan 21, 2020 3:57 am
Forum: Technical/Operations
Topic: Future VLA Market?
Replies: 91
Views: 5159

Re: Future VLA Market?

Bjorn Fehrm's Fundamentals of Airliners, Part 6, has a good interview illustrating my rationale for the mixed-engine quad proposal: let’s start with the question we put to CFM through their director of Strategic Communication, Jamie Jewell. In Power Points around the LEAP, it is described as having ...

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by Matt6461
Tue Jan 21, 2020 3:20 am
Forum: Technical/Operations
Topic: Future VLA Market?
Replies: 91
Views: 5159

Re: Future VLA Market?

The question is whether the decreased fuel consumption of a trijet makes up for the poor aerodynamics compared to a quad jet. You're begging the question by assuming as a premise something you need to prove as part of your argument. First you need to establish that there is, in fact, decreased fuel...

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by Matt6461
Tue Jan 21, 2020 1:28 am
Forum: Technical/Operations
Topic: Future VLA Market?
Replies: 91
Views: 5159

Re: Future VLA Market?

The technology exists for a trijet with the same capacity as the 747-8. Take the engines from the 77W [and] make the fuselage [6 metres] longer and a couple [centimetres] wider than the 779. This will allow comfortable ten-abreast seating. Add a third engine in the tail and you have a 748 trijet wi...

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by Matt6461
Tue Jan 21, 2020 1:22 am
Forum: Technical/Operations
Topic: Future VLA Market?
Replies: 91
Views: 5159

Re: Future VLA Market?

Fine, how would your design comply with FAR 121.193 which says, 2) Its weight, according to the two-engine inoperative, en route, net flight path data in the Airplane Flight Manual, allows the airplane to fly from the point where the two engines are assumed to fail simultaneously to an airport that...

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by Matt6461
Mon Jan 20, 2020 5:55 am
Forum: Technical/Operations
Topic: Future VLA Market?
Replies: 91
Views: 5159

Re: Future VLA Market?

Well, what if the quadruplets were the cheap engines? Could totally change the equation, especially if there weren't somewhat "off-the-shelf" larger and smaller engines. If you look at this article, it suggests 10-20% of DOC is engines. If you make that more complex and add 1 pp to save 1...

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by Matt6461
Tue Jan 14, 2020 6:33 pm
Forum: Technical/Operations
Topic: Future VLA Market?
Replies: 91
Views: 5159

Re: Future VLA Market?

If I'm transparently stupid you really could use a mirror. And in accordance with the forum rules, you might want to cool your jets mon frere. I've said nothing about you personally, only your argument. In fact, I've said that many very smart people made your bad argument during decades of A380 mar...

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by Matt6461
Tue Jan 14, 2020 6:17 pm
Forum: Technical/Operations
Topic: Future VLA Market?
Replies: 91
Views: 5159

Re: Future VLA Market?

A350s for China and 787s for India are already packed to the damn gills I stand corrected. You haven't made zero arguments; you've partially made at least one transparently stupid argument. To complete this bad argument, your next step would be, "given that these [fish, apparently] have no gil...

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by Matt6461
Tue Jan 14, 2020 6:06 pm
Forum: Technical/Operations
Topic: Future VLA Market?
Replies: 91
Views: 5159

Re: Future VLA Market?

Statistics 101 Yeah thanks for telling me the difference between median and mean. I asked for an argument. You still have not made one. You're citing a "lies, damn lies" in the manner of a person who has seen one Youtube video. Nor have you responded to the other poster who has told you h...

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by Matt6461
Tue Jan 14, 2020 5:57 pm
Forum: Technical/Operations
Topic: Future VLA Market?
Replies: 91
Views: 5159

Re: Future VLA Market?

given those regions are expanding passenger loads on long haul far faster than Singapore or the Middle East 3, there is a trend toward larger jets than the A321XLR and B787 being needed. . Again you need the barest amount of quantitative analysis. Take PVG: Per wikipedia, ~146 pax/movement. So the ...

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by Matt6461
Tue Jan 14, 2020 5:47 pm
Forum: Technical/Operations
Topic: Future VLA Market?
Replies: 91
Views: 5159

Re: Future VLA Market?

given those regions are expanding passenger loads on long haul far faster than Singapore or the Middle East 3, there is a trend toward larger jets than the A321XLR and B787 being needed. . Again you need the barest amount of quantitative analysis. Take PVG: Per wikipedia, ~146 pax/movement. So the ...

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by Matt6461
Tue Jan 14, 2020 5:36 pm
Forum: Technical/Operations
Topic: Future VLA Market?
Replies: 91
Views: 5159

Re: Future VLA Market?

keesje wrote:
How many windtunnels have you seen from the inside or aircraft have you calculated induced, paracit drag for ..


How much wood could a woodchuck chuck?

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by Matt6461
Tue Jan 14, 2020 5:03 pm
Forum: Technical/Operations
Topic: Future VLA Market?
Replies: 91
Views: 5159

Re: Future VLA Market?

You'rd being generous. There is a very well-known poster here (hint: fly) with whom I had a long argument on precisely this topic and, believe me, reference area wasn't even dreamed of in his philosophy. .. But the other poster took a class that, in America, a fairly unremarkable "gifted"...

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by Matt6461
Tue Jan 14, 2020 3:14 pm
Forum: Technical/Operations
Topic: Future VLA Market?
Replies: 91
Views: 5159

Re: Future VLA Market?

patrickjp93 wrote: So there's more going on here than just total surface area per passenger. There is, cross-sectional area not really being one of them. Thank you. I would guess that the drag approximation for an automobile uses frontal area as the reference area You'rd being generous. There is a ...

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by Matt6461
Tue Jan 14, 2020 12:01 am
Forum: Technical/Operations
Topic: Future VLA Market?
Replies: 91
Views: 5159

Re: Future VLA Market?

My guess is that practical considerations like maintenance, etc. kill the business case, even if the math were to work out a few % better. I can totally see that being the case; I'm not convinced either. To be convinced, I'd need a squad of engineers, accountants, and management analysts, as would ...

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by Matt6461
Mon Jan 13, 2020 10:42 pm
Forum: Technical/Operations
Topic: Future VLA Market?
Replies: 91
Views: 5159

Re: Future VLA Market?

I don't understand why you would need two different types of engines optimised for take-off and cruise respectively. Are the regimes really that different when it comes to RPM? Turbofans are running at 80-85% N1 in the cruise. The big change is mass flow. The issue isn't RPM, it's factors like clea...

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by Matt6461
Mon Jan 13, 2020 10:26 pm
Forum: Technical/Operations
Topic: Future VLA Market?
Replies: 91
Views: 5159

Re: Future VLA Market?

I took university level physics, including basic aerodynamics and aced it. That article is largely old hat from the days before we actually perfected laminar coatings. Also, NASA themselves would disagree with Leeham here. https://www.grc.nasa.gov/www/k-12/airplane/drageq.html Ok genius. I could sp...

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by Matt6461
Mon Jan 13, 2020 9:42 pm
Forum: Technical/Operations
Topic: Future VLA Market?
Replies: 91
Views: 5159

Re: Future VLA Market?

Uh, no, the part that produces (most of the) drag is the cross-section, not surface area, and the cross section is about 35% larger than the 777X, not to mention the wings' cross section also matters here. Also, the wider fuselage also produces more lift from below as well, especially if it's ovoid...

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by Matt6461
Mon Jan 13, 2020 8:43 pm
Forum: Technical/Operations
Topic: Future VLA Market?
Replies: 91
Views: 5159

Re: Future VLA Market?

I don’t see anything explicitly addressing the OEI case where there exist two different engines on quad. Not saying it can’t be done, I’d just like to see the specifics. Hint: loss of an engine in a quad has a higher net climb gradient than a twin, so loss of one of the big engines will be an issue...

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by Matt6461
Mon Jan 13, 2020 7:35 pm
Forum: Technical/Operations
Topic: Future VLA Market?
Replies: 91
Views: 5159

Re: Future VLA Market?

When the A380s retire from Lufthansa, Air France, and British, there'll be a pretty heavy squeeze at exactly the wrong time imho. You need to do a little - at least SOME - numerical analysis on this. Take FRA: ⋅ Per Wikipedia, it has ~1,400 movements/day. ⋅ LH bases 8 A380's the...

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by Matt6461
Mon Jan 13, 2020 7:18 pm
Forum: Technical/Operations
Topic: Future VLA Market?
Replies: 91
Views: 5159

Re: Future VLA Market?

I'd argue the 777X isn't selling like hot cakes yet for a few reasons besides the ones you mentioned. 737 MAX brings to light culture problems at Boeing that may have tainted the 777X as well, so airlines will wait and see how it goes with Emirates and Singapore The 777-300ERs around the world are ...

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by Matt6461
Mon Jan 13, 2020 7:01 pm
Forum: Technical/Operations
Topic: Future VLA Market?
Replies: 91
Views: 5159

Re: Future VLA Market?

in terms of aerodynamics, the double-decker is less efficient at the same passenger load (you get higher drag/length and less lift/length) No. I really honestly don't mean any offense by this, I mean this only in the spirit of information, but you're ignoring the basics of aerodynamics. What causes...

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by Matt6461
Mon Jan 13, 2020 5:30 pm
Forum: Technical/Operations
Topic: Future VLA Market?
Replies: 91
Views: 5159

Re: Future VLA Market?

Given the prospects of another 1 billion annual fliers in the air yearly by the mid 2030s, do we still have room for birds bigger than the 777-9 while the economics of direct lesser hub flight are also changing? Under current trends, I doubt we'll have much room for birds as big as the 777-9, inclu...

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by Matt6461
Mon Jan 13, 2020 5:18 pm
Forum: Technical/Operations
Topic: Future VLA Market?
Replies: 91
Views: 5159

Re: Future VLA Market?

If another VLA gets built, it'll likely be a quad for reasons mentioned above: cheap engines to share with a twin, and better ground clearance, etc. A quad is a better layout than a trijet. This is definitely one possibility. Depending on the size of the VLA, however, another possibility is sharing...

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by Matt6461
Mon Jan 13, 2020 5:11 pm
Forum: Technical/Operations
Topic: Future VLA Market?
Replies: 91
Views: 5159

Re: Future VLA Market?

You need to study Part 25 and AC 25-7 to realize a quad designed that way doesn’t work. Failure of one of the big engines at V1 needs to be accounted for and that probably won’t work. You need to read the thread before assuming I didn't account for failure of one of the big engines. It's explicitly...

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by Matt6461
Mon Jan 13, 2020 5:03 pm
Forum: Technical/Operations
Topic: Future VLA Market?
Replies: 91
Views: 5159

Re: Future VLA Market?

I posted ideas about an A380 successor a long time ago (when folks were still deluded that the A380 was a good airplane). https://www.airliners.net/forum/viewtopic.php?t=776333#p19165661 The talk of tri-jets is unnecessary. From the fundamentals of drag you should be able to see that a twin VLA (>45...

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by Matt6461
Sun Oct 13, 2019 2:54 am
Forum: Civil Aviation
Topic: Boeing examines GEnX powered 767
Replies: 617
Views: 147305

Re: Boeing examines GEnX powered 767

I think I created posts on that 13, 7, 2, 1 years ago. First I had the Dreamliner crowd all over me (787 = 767 replacement) later on the MOM/NMA crowd. Always felt it was a reasonable idea. The 767 is 30t lighter than the A330/787, right sized, got significant updated for the -400ER and KC-46. And ...

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by Matt6461
Fri Aug 30, 2019 3:07 pm
Forum: Civil Aviation
Topic: MC-21 Development Thread
Replies: 520
Views: 148402

Re: MC-21 Development Thread

I know I'm like a broken record at this point - but this is pretty much what Boeing should be doing for their MoM. Then port the fuselage back down to NSA in the future. Indeed, I'd offer a whole product line based on that fuselage as its common centre. 797-100 ==> 180 seat fuse, 3000nm range wings...

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by Matt6461
Sun Aug 11, 2019 4:45 am
Forum: Technical/Operations
Topic: Did/Does the 779X need a new wing? and does it need to be so big?
Replies: 47
Views: 8811

Re: Did/Does the 779X need a new wing? and does it need to be so big?

The A330 wing is swept much less than the 747. 30 degrees vs 37.5 degrees. Could that somewhat explain the cruise speed difference? Yes, that's part of it for sure. Forgot to mention that element: modern airfoil design allows for less sweep at a given critical mach number (or higher mach for a give...

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by Matt6461
Sat Aug 10, 2019 6:52 pm
Forum: Technical/Operations
Topic: Did/Does the 779X need a new wing? and does it need to be so big?
Replies: 47
Views: 8811

Re: Did/Does the 779X need a new wing? and does it need to be so big?

As the cruise speeds are slower, you can have a thicker wing with less form drag, which means you can make it stronger for a given weight. I once tried to pencil out the cost/benefit of thicker, lighter wings versus higher wing form drag. From those two parameters I couldn't see why every airplane ...

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