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Why Is A B777 Faster Than An A340  
User currently offlineGRIVely From United States of America, joined Dec 2006, 139 posts, RR: 0
Posted (8 years 1 week 12 hours ago) and read 16541 times:

Last summer I was on business in Europe with the president of my company. We both left FRA for IAD about the same time. He was on a UA B777 and I was on an LH A340 (might have been a 400, not sure). I was in business on the right side just in front of the wing. As we were crossing the Irish coast arcing over onto the great circle route I noticed another aircraft coming up beside us on the right.

It pulled level with us and I could see it was a UA 777. We flew in companionable silence for a few minutes and then it started pulling away from us, not too quickly, but very steadily and in less than 10 minutes was completely out of my line of sight.

On the ground in IAD I linked up with my colleague and we discovered that was his 777 and he had seen the A340 from his left side seat. He landed at IAD about 40 minutes before I did so he had a coffee and read the paper while waiting for me.

What is there about the 777 that makes it that much faster than the A340?

Thanks in advance for any illumination.

65 replies: All unread, showing first 25:
 
User currently offlineIkramerica From United States of America, joined May 2005, 21589 posts, RR: 59
Reply 1, posted (8 years 1 week 12 hours ago) and read 16520 times:

Short answer: Boeing designed it to be faster, nearly as fast as the 747, so it was more interchangeable in the scheduling. It also means that for certain routes, one 777 can do the route daily, but it would require 1+ A340s.

Airbus knows this is a severe disadvantage, and I am sure customers have told them so, because both the A380 and A350 have been designed to fly faster. But flying faster has an effect on fuel efficiency in cruise.

The fact that the 777LR series is faster, more efficient and more reliable than the A340NG was the triple win that broke the A340s, back. Had the A340 had the clear advantage in any of those categories, sales would not have dropped off the cliff like they did.



Of all the things to worry about... the Wookie has no pants.
User currently offlineBeech19 From United States of America, joined Jul 2006, 936 posts, RR: 4
Reply 2, posted (8 years 1 week 12 hours ago) and read 16510 times:

Quoting Ikramerica (Reply 1):
Airbus knows this is a severe disadvantage, and I am sure customers have told them so, because both the A380 and A350 have been designed to fly faster. But flying faster has an effect on fuel efficiency in cruise.

The crazy part is... the 747 will STILL be the fastest commercial aircraft in the world. And the 748 will be Mach .005 faster than the 744.



KPAE via KBVY
User currently offlineArsenal@LHR From United Kingdom, joined Mar 2001, 7792 posts, RR: 19
Reply 3, posted (8 years 1 week 12 hours ago) and read 16499 times:
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The simple answer is that the 777 has a higher cruise speed than the A340 (all models) Mach 0.84 i believe versus the A340-300's Mach 0.82. Other factors such as aerodynamics and wing design have a lot of bearing on speed. A340's have four engines which i assume increases drag more than a twin such as the T7. The higher thrust rating on 777's wings than the A340's might make a difference in speed although someone correct me if i'm wrong.


In Arsene we trust!!
User currently offlineIkramerica From United States of America, joined May 2005, 21589 posts, RR: 59
Reply 4, posted (8 years 1 week 12 hours ago) and read 16460 times:

On a recent 744 flight, we flew mach .89 the whole way to make up for a 2 hour delay and a curfew on the other end. The fact we had 100 or so pax didn't hurt the cause, either.

The A380 should be able to do that too, but no other Airbus plane can do that right now. Not even close. The T7 can almost sustain that, but I am not sure about the first half of the flight when it is swollen with fuel...



Of all the things to worry about... the Wookie has no pants.
User currently offlineAri From UK - England, joined May 2005, 131 posts, RR: 0
Reply 5, posted (8 years 1 week 12 hours ago) and read 16425 times:

I remember travelling at +1000kmh on an SQ B772. I think it was around 1052ish but cant be sure but we had a hell of a tailwind!!

aRi


User currently offlineKiwiandrew From New Zealand, joined Jun 2005, 8632 posts, RR: 13
Reply 6, posted (8 years 1 week 12 hours ago) and read 16405 times:
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Quoting GRIVely (Thread starter):
He was on a UA B777 and I was on an LH A340 (might have been a 400, not sure).

an A340-400 ??? -200/-300/-500/-600 sure , but I have never heard of an A340-400



Moderation in all things ... including moderation ;-)
User currently offlineSNATH From United States of America, joined Mar 2004, 3247 posts, RR: 22
Reply 7, posted (8 years 1 week 12 hours ago) and read 16407 times:

Quoting GRIVely (Thread starter):
(might have been a 400, not sure)

First, welcome to the "family"! LH's A340 was most likely a -300. FYI, the A340 has no -400 submodel.

Quoting Beech19 (Reply 2):
The crazy part is... the 747 will STILL be the fastest commercial aircraft in the world. And the 748 will be Mach .005 faster than the 744.

Here's an interesting data point. I've flown BOS-FRA on LH many times in the past. I've done it on both B747s and A340s. They have slightly changed the times now, but a couple of years ago the early flight was scheduled for 430pm for a 530am arrival if it was an A343. When, during the winter they switched to a B744, they departure time was moved to 445pm for the same arrival (530am). It was pretty cool, as I could guess what type of plane it'd be just be looking at the departure time!  Smile

Quoting GRIVely (Thread starter):
and then it started pulling away from us, not too quickly,

One of the coolest things I've seen while flying was when I was doing GLA-YYZ on an AC B767. I was reading a book and suddenly something caught me eye outside. I looked and it was a NW B774 passing us slightly below us. It overtook us so fast, that I only had the time to snap two pictures before it disappeared "into the distance"... I was quite impressed!

Tony



Nikon: we don't want more pixels, we want better pixels.
User currently offlineCobra27 From Slovenia, joined May 2001, 1034 posts, RR: 0
Reply 8, posted (8 years 1 week 12 hours ago) and read 16306 times:

Quoting GRIVely (Thread starter):
What is there about the 777 that makes it that much faster than the A340?

The speed advantage is only 0.02-0.04 Mach. Not much really


User currently offlineGigneil From United States of America, joined Nov 2002, 16347 posts, RR: 85
Reply 9, posted (8 years 1 week 12 hours ago) and read 16289 times:

Quoting Beech19 (Reply 2):

The crazy part is... the 747 will STILL be the fastest commercial aircraft in the world. And the 748 will be Mach .005 faster than the 744.

The A380 will cruise at M0.86, which is faster than the 744's standard cruise.

The A380 also has a sprint cruise of M0.89, like the 744 and 748.

For all intents and purposes, they are both fast.

NS


User currently offlineBeech19 From United States of America, joined Jul 2006, 936 posts, RR: 4
Reply 10, posted (8 years 1 week 12 hours ago) and read 16241 times:

Quoting Cobra27 (Reply 8):
The speed advantage is only 0.02-0.04 Mach. Not much really

That turns into to a half hour of flight time on a very long flights of 7000nm+. Thats over and over every day. That is a lot of extra potention flight time and any time you can cut a super long flight shorter, you do.



KPAE via KBVY
User currently offlineIkramerica From United States of America, joined May 2005, 21589 posts, RR: 59
Reply 11, posted (8 years 1 week 12 hours ago) and read 16212 times:

Quoting Cobra27 (Reply 8):
The speed advantage is only 0.02-0.04 Mach. Not much really

That's 30 minutes on a long haul flight. Can mean the difference between getting in 1 turn a day, or less.

There was a reason Boeing was pushing the Sonic Cruiser when fuel was cheap. Fixed costs would be drastically lower as fewer jets would be needed in a fleet. Also, routes that required 2 crew rotations in flight could be pared to a single crew in some cases. Of course, that was more than 0.02 mach, but that was the point. And airlines had major interest until 9/11 and then the price of oil...

Quoting Gigneil (Reply 9):
The A380 will cruise at M0.86, which is faster than the 744's standard cruise.

I thought it had been paired back to 0.855, which is what the 748i is also listed as.



Of all the things to worry about... the Wookie has no pants.
User currently offlineJogales From United States of America, joined Aug 2005, 437 posts, RR: 0
Reply 12, posted (8 years 1 week 10 hours ago) and read 15864 times:

Quoting GRIVely (Thread starter):
What is there about the 777 that makes it that much faster than the A340?

You tell me Big grin

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Josh  Wink



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User currently offlineLegoguy From United Kingdom, joined Jun 2006, 3314 posts, RR: 39
Reply 13, posted (8 years 1 week 10 hours ago) and read 15790 times:

Quoting SNATH (Reply 7):
NW B774

Presume you mean 747  Silly

Since the a340 has wings with less sweep, does this give better low speed handling?



Can you say 'Beer Can' without sounding like a Jamaican saying 'Bacon'?
User currently offlineJAL From Canada, joined Apr 2000, 5093 posts, RR: 8
Reply 14, posted (8 years 1 week 10 hours ago) and read 15701 times:

Wow!!! Didn't know that the 777 was that faster than the A340!


Work Hard But Play Harder
User currently offlineAntskip From Australia, joined Jan 2006, 936 posts, RR: 6
Reply 15, posted (8 years 1 week 10 hours ago) and read 15686 times:

Quoting Ari (Reply 5):
remember travelling at +1000kmh on an SQ B772. I think it was around 1052ish but cant be sure but we had a hell of a tailwind!!

Aircraft fly within air, not on the ground. If +1000kmh was ground speed, it is just a record of speed relative to the ground - made up of the sum total of vehicular speed and local air movement. A plane flying at 100 kmh into a 100 kmh head wind would be not moving at all, relative to the ground. With a 100 kmh tail wind, it would be flying at 200 kmh relative to the ground, though the vehicle's air speed is unchanged.


User currently offlineGigneil From United States of America, joined Nov 2002, 16347 posts, RR: 85
Reply 16, posted (8 years 1 week 9 hours ago) and read 15659 times:

Quoting Legoguy (Reply 13):
Since the a340 has wings with less sweep, does this give better low speed handling?

Absolutely. Its a philosophical difference.

Airbus' wings are optimized to provide more lift but less speed, which is why both the A330 and the A340 fly with much less installed thrust than their Boeing counterparts.

Boeing installs more thrust to get the plane in the air, then they scream through the sky.

Quoting LHR777 (Reply 14):
Based on the above pictures - one has two engines, the other has four hair-dryers........

Nothing even remotely at all to do with it.

NS


User currently offlineSNATH From United States of America, joined Mar 2004, 3247 posts, RR: 22
Reply 17, posted (8 years 1 week 9 hours ago) and read 15463 times:

Quoting Legoguy (Reply 13):
Presume you mean 747

Nah, it's a new designation for a B747 with a DC-9 body bolted onto it to extend its capacity...  Smile

Tony



Nikon: we don't want more pixels, we want better pixels.
User currently offlineFlyDreamliner From United States of America, joined Jan 2006, 2759 posts, RR: 15
Reply 18, posted (8 years 1 week 8 hours ago) and read 15288 times:

Quoting Ikramerica (Reply 4):
The A380 should be able to do that too, but no other Airbus plane can do that right now. Not even close. The T7 can almost sustain that, but I am not sure about the first half of the flight when it is swollen with fuel...

The 747 will still have a faster sprint speed than the A380, with 747-8 being able to do a max cruise of .89, and a max mach number of .92, as compared to a max mach on .89 on A380, but only by a shade, they'll cruise pretty close to each other. The 777 can run at near 747 cruise, but again, lacks 747's full sprint ability. The 787 will cruise at roughly 748 speeds, though its sprint capabilities are yet to be seen.

Quoting Gigneil (Reply 9):

The A380 will cruise at M0.86, which is faster than the 744's standard cruise.

Will it be .86 or .85....

Quoting Gigneil (Reply 18):
Airbus' wings are optimized to provide more lift but less speed, which is why both the A330 and the A340 fly with much less installed thrust than their Boeing counterparts.

Much less? the A343 has a real fight to get in the air fully loaded. A346IGW actually has more thrust on it than 773ER, then again 773ER has a lower empty weight (allowing it to carry more payload and burn less fuel doing it).

The big thing that impacts speed is the wing. The airbus wing is intended for a more conservative layout, giving more low altitude lift, at the cost of top speed... also, less swept wings end up being lighter more often.

In order to fit more wing into a smaller span, the 747 used a 37.5 degree sweep, which translated into a higher cruising speed. The 777's sweep is somewhat similar to that in A340, moreso A345/346, however, A380 uses a 33.5 degree wing,



"Let the world change you, and you can change the world"
User currently offlineGRIVely From United States of America, joined Dec 2006, 139 posts, RR: 0
Reply 19, posted (8 years 1 week 8 hours ago) and read 15185 times:

Thank you everyone for the most thoughtful replies and the cogent illumination of the issues. (Note attempt to measure up to the high standards of the A.netters. Well, most of the crew anyway.)

Ta.


User currently offlineViscount724 From Switzerland, joined Oct 2006, 26021 posts, RR: 22
Reply 20, posted (8 years 1 week 7 hours ago) and read 15102 times:

Even the almost 50-year-old 707 and DC-8 is faster than the A330/340. The 707 is marginally faster than the DC-8, largely due to the 707's slightly greater wing speep angle (same as the 747 if not mistaken), but the difference between the 707 and DC-8 speed is much smaller than between a 747/777 and A330/340. As has been mentioned by others, that can easily make a difference of 30 to 45 minutes on long sectors of 10 or 12 hours.

The DC-10/MD-11 are also faster than the 330/340 (and 300/310).


User currently offlineIkramerica From United States of America, joined May 2005, 21589 posts, RR: 59
Reply 21, posted (8 years 1 week 6 hours ago) and read 14890 times:

Quoting Gigneil (Reply 18):
Boeing installs more thrust to get the plane in the air, then they scream through the sky.

That is not really true when comparing the 343 to the 772 or the 346 to the 773.

As twins, the 777 must have more installed thrust because with one engine out, a single engine must have enough thrust to continue takeoff, keep the plane aloft and safely land.

On the 77W, that's 115k. The 346 must have enough thrust so that 3 engines can do that. On the 346, that is 168k pounds. Well, the 346 likely needs less than 168k to do this, but since 2 engines produce 112k, the number is somewhere between 112k and 168k. But this example shows the A340 requires MORE installed thrust on an engine out basis than does the 777, which is one measure of which frame is more efficient.

On the 343, the highest thrust version has 34k engines, so engine out thrust is 102k, which is again higher than the thrust on any 772ER engine available (IIRC, the most powerful 772ER engine is 94k)...



Of all the things to worry about... the Wookie has no pants.
User currently offlineMBJ2000 From Germany, joined Dec 2005, 426 posts, RR: 0
Reply 22, posted (8 years 1 week ago) and read 14672 times:

Quoting FlyDreamliner (Reply 20):
Much less? the A343 has a real fight to get in the air fully loaded. A346IGW actually has more thrust on it than 773ER, then again 773ER has a lower empty weight (allowing it to carry more payload and burn less fuel doing it).

The big thing that impacts speed is the wing. The airbus wing is intended for a more conservative layout, giving more low altitude lift, at the cost of top speed... also, less swept wings end up being lighter more often.

In order to fit more wing into a smaller span, the 747 used a 37.5 degree sweep, which translated into a higher cruising speed. The 777's sweep is somewhat similar to that in A340, moreso A345/346, however, A380 uses a 33.5 degree wing,

Interesting numbers, I wonder how Airbus managed to keep the less swept wings and still reach a higher cruising speed for the A380? Just by using more thrust at the expense of higher fuel burn?



Like most of life's problems, this one can be solved with bending -- Bender Unit 22
User currently offlineLHR777 From , joined Dec 1969, posts, RR:
Reply 23, posted (8 years 6 days 23 hours ago) and read 14597 times:

Quoting Gigneil (Reply 18):
Nothing even remotely at all to do with it.

No, really? Thanks for that clarification....  Yeah sure

..now back to more serious matters, as having a bit of a laugh is obviously frowned upon......


User currently offlineKeesje From , joined Dec 1969, posts, RR:
Reply 24, posted (8 years 6 days 23 hours ago) and read 14552 times:

I think "the 777 beat the A340" kind of topic is on the brink off taking over the "when will NWA replace their DC9s" topics / open questions..

It even get endlessly referred too by many members irrespective off the running topic. And not only on a.net.

 rotfl   rotfl   rotfl 


25 Acidradio : Will that happen when they actually replace their DC9's?
26 Zeke : The difference is in engineering, nothing more. Airbus went to the airlines and they were happy with the 340 cruise speed before it went into final de
27 RJ111 : You have assumed that the A340 has chosen the bare minimal power to take off on 3 engines. In reality this usually is untrue for a quad as it would r
28 Post contains links and images Keesje : On the otherside having a "fast" wing also leads to it being fast during landing take-off. E.g. the 747 has a much higher landing / take-off speed an
29 Zeke : 1...The 346 has 67436lb less thrust on it the the 773ER, you are looking at the 5 min takeoff rating, not the max sea level (773ER =110000x2 and 346
30 Autothrust : From all this posts i can assume Airbus did a very good job with the A380 wing. It can cruise at 0,89 and the A380 needs less runway for takeoff and
31 Aviator27 : The short simple answer to your question is design. Boeing and Airbus had different long range airplane strategy. Boeing wanted faster and more effici
32 OldAeroGuy : To approach this discussion in parts, why is an A333 (LRC@0.82M) faster than a A343 (LRC@0.81M)?
33 Post contains images Lightsaber : Nice summary. Thank you. It will be interesting to see how the 748 modifies the flaps. Yes, the modification is mostly for noise (QC2 compliance), bu
34 CHRISBA777ER : I have to say thats pretty incredible. Thus is another a-net myth debunked.
35 PlainSmart : Has anyone mentioned cost index? Cost index is a value entered into the FMS that calculates the the speeds to be flown. This is dependant on fuel, del
36 Post contains links Xv408 : One of the significant factor to note with aircraft speed and wing angles etc is the profile of the wing. Research in the 60's developed the suprcriti
37 Post contains images Beech19 : LOL Those monster GE-90's should be the 8th wonder of the world. I've done -mph in our Aeronca 7AC Champ. 27knot stall, 35knot headwind. LOL Look dow
38 Post contains images Keesje : Which is faster, You tell me
39 Post contains images OHLHD : It is so fast, you can´t even see it This topic made my day
40 Beech19 : The 727 is... its got nothing to do with the motors... i think that point had already been made clear.
41 LH648 : Tupolev 154 is faster.
42 Post contains links Beech19 : No its not. MAX Mach is .86. As we have already established previously the 747-400/ER/ERF MAX Mach is .92 and the 748i/F maybe more, but will be at l
43 LukasMako : Don't forget that ETOPS restrictions can make the 777 slower than the A340 on certain routes.
44 Lostmoon744 : Re: TU-154: Curious to note the NATO reporting name as "Careless". My word! What's the history behind the designation?
45 Beech19 : But that is more to do with the airline not getting a high enough ETOPS rating, not necessarily that the aircraft is actually "slower" it just has to
46 Post contains links PhilSquares : The 380 will cruise at M.85 http://events.airbus.com/a380/seeing/learnandplay/figures3.asp In reality, the 744 is closer to M.86. LRC is about .855-.
47 Planemaker : Any Citation X pilots reading? Any validity to Cessna's claim that the Citation X is the fastest "civil" (which included commercial) aircraft flying?
48 Post contains links Beech19 : It has a max cruise of .92 with sprints to like .94 at 51,000ft from what i hear. There is nothing like a Citation X, i love the GF's but Cessna did
49 Post contains images Scooter01 : This is why the Boeing people named it the DC-Late Is this why it looks so funny at final approach? (I'm talking about the entertainment factor) You
50 Post contains images TinkerBelle : I flew OZ 772 2 days ago ICN-SFO and I noticed the damn thing was 'flying', literally. Our crise speed for most of the flight was 748mph. Never been o
51 Post contains images Birdbrainz : There's a little bit of additional history here: At the time the A330/340 came out, the 767 was doing very well and it was designed for a lower cruise
52 Supa7E7 : Yes, that's because there was probably a 200mph jet stream tailwind. The Boeing flew at 550 mph, and that plus tailwind may equal 748 mph (but that i
53 Post contains images Vref5 : Ahhh. What you were seeing was the groundspeed. Plane moves across the air at the same speed BUT how fast it moves over the ground depends on wind ad
54 T773ER : The A380's cruise speed is mach .85 check it out, its on the airbus website.
55 B737700doctor : Both a/c have there advantages. But all in all the Boeing company have the best wings ever made for commercial aircraft. Boeing and Airbus both contra
56 Zeke : Airbus UK, Airbus Spain for Airbus wings 787 .... made in Japan, not made in the USA, not made by Boeing. Not by a long way, even Randy concedes that
57 Planemaker : Ah... another fave is the Convair 990. Too bad that failed in the market! It was nice having it around for awhile.
58 Flyibaby : Although the 777 is faster, everyone is also forgetting flying over the North Atlantic uses the track system. Therefore, all aircraft are flying only
59 Vref5 : Actually, 1,000 ft if participating in RVSM between FL290-FL410. (Minor nit.) No significant disagreement otherwise, though.
60 Beech19 : Not made by the hands of Boeing but designed by still. Does Airbus outsource the design to someone else or do they make there's too? (i would assume
61 Post contains images Blrsea : Wow, a really civil A Vs B thread! Been a long time since I saw one West bound ICN-SFO is generally faster due to the prevailing tailwinds. EAstbound
62 Prebennorholm : It is the combination of wing airfoil section and wing sweep which influences at what speed trans-sonic drag builds up, and therefore dictates max cr
63 Zeke : I think the early wings were designed by BAe in the UK, Airbus was a BAe and EADS company at the time. The design and manufacturing for the wings at
64 Post contains images TinkerBelle : I sure did, Thank God it was shorter than I expected. Your explanation makes sense coz I took the same flight in October and it took us 11 hours ICN-
65 Beech19 : Thanks for that info.
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