Why are Airbus Heavier than Boeing

[stilton]

It appears that, across the product range the Airbus product, matched as closely as possible to it's Boeing counterpart is generally a heavier (in some cases significantly) airframe.

Of course this does not help their comparative performance, but I am curious as to why the disparity?

[Capt Claret]

Airbus are better built. :\

[Grunf]

Hello. Hard to say since you did not say which models are you comparing.

Boeing is usually overshooting design (used to make slightly heavier a/c in order to have more "margin of safety" in its structure = room for derivatives).

Airbus, more or less, goes for more precise "zero margin" approach. That asks for some skills when you want to go and certify a derivative that will carry more payload (passengers, cargo).

Cheers,

[john_tullamarine]

If I recall correctly, the A320 (and probably others in the fold) did a trade off whereby the FBW capability to modify pilot inputs was used to run the structural reserve margin down somewhat. This resulted in a lighter empty weight and the Airbus machine having a good payload to gross ratio.

[galaxy flyer]

With regards to the A380 and it recent wing "rupture" during test, M. Garcia, V-P Engineering noted, "while the result means the wing doesn't have any extra performance margin, it also means it isn't carrying any unnecessary structure." (Aviation Week,Feb 20,06 pg 44)

Does that mean anything with regards to weight?? Maybe not, but Boeing's wings tend to have engines better distributed span-wise which they claim saves weight. I think the A340's wing is lighter than the A330's due to wing bending relief.

GF

[TopBunk]

OK lets take the 737-400 vs the A320, both with CFM56 engines and 150 seats.

B737-400 basic weight about 34 tonnes
A320 basic weight about 45 tonnes.

Note the A321 with 196 seats basic weight is only about 46 tonnes, ie an increase of 1 tonne for 40 extra seats!

[longarm]

Don't know about the 737-400 but the A320 can comfortably seat 180 single class not just 150.

[Flip Flop Flyer]

Another comparison:

A320 OEW (CFM56): 42.1
Range with 150 pax: Up to 3090NM
Max pax: 180
B737-800 OEW: 41.1
Range with 160 pax: Up to 2940NM
Max pax: 189

Not much of a difference, but coupled with a slight pax disadvantage.

A321 OEW (CFM56): 47.9
Range with 185 pax: Up to 3000NM
Max pax: 220
B737-900ER OEW: 43.4 (est, Boeing claims it'll be "4536 kgs lighter than A321")
Range (no pax info): 3200NM
Max pax: 215

If Boeing keeps it word, rather a sizeable difference. Slightly fewer pax, but more range.

[52049er]

IIRC Airbuses are made out of thicker gauge metal. Contrary to the myths, they are, if anything, more robust than Boeings, as well as having a far more modern build procedure - ie if you need a new fuselage panel for a 'bus you can order one from the factory and it will fit the old hole - rivet holes included as the panels are machine fitted. As Boeings are made like farm machinery by rivetters (sp?) each panel is different and need to be custom fitted (often with judicious use of a lump hammer).

[F4F]

on the Bus, part of the extra weight must be the main landing gear doors :ok:

though this should be more than offset by the forest of vortex generators and the lenght of any lever or switch on the FDK of the 737 :}

[alexban]

52049..I suspect you've been to Seattle and saw the farmers armed with hammers building those 'ugly' ,bulky Boeing planes,right?:} Thicker metal,right?..:sad:
You should watch Discovery ch more often dude...

[52049er]

Sorry alexb, dont get much time to watch telly, what with flying a 74-400 around the world (oh and racking up 3500 hrs on M. Airbus' products before that, dude.)

[Grunf]

52049er:

You're right for the difference in technology but it would be fair to mention that 747 is a 60's technology a/c while Airbus (any model) came a generation later.

If you do a comparison with 777 it would be a different story. Same holds for 37NG and partially for 67s and 57s.

I've been working both sides and to tell you the truth it is more or less the same, in the end. Amount of work in MRO is what it counts and systems and engines are far more complex and demanding then structure.

Cheers

[davedek]

Sorry alexb, dont get much time to watch telly, what with flying a 74-400 around the world (oh and racking up 3500 hrs on M. Airbus' products before that, dude.)

Yeah I believe you, all the 747 pilots I know refer to each other as 'dudes' :rolleyes:

[Johnbr]

Flown both B737's and A320/319's at the same kind of operations and the Airbuses outperform the boeings by far.T.O. and landing performance on the airbuses are much better.Comparisons have bee made,on simulators and ,in the cfit recovery,windshear recovery the hard protected flight controls sys on the Airbus proved to safer and easier than the soft protected sys on the B-777,although the pilots,all of them americans of course "decided" that they rather have the capabiliyt to "override the protections of the Airbus in case of a situation like those arises.As for watching Discovery channel,give me a break!!!Pure and simple payd for by Boeing!!!In the program about the accident with the airbus in the airshow back in the late 80's they stated,and I quote:"the flight controls sys,locked up !!!"And we know that ain't true,don't we???

[Rick Storm]

The a/c recovered...........

http://i16.photobucket.com/albums/b9/dazdaz1/image001.jpg

[alexban]

Is this picture for real? When did it happen? Why did the fly-by-wire protection allowed this to happen?
Or is it fake,as I think it is..:}

[kms901]

Don't know about farmers at Boeing. Plenty of non-native english speaking Mexicans though !

[hawk37]

Alexban, what protection would be in place to prevent this? Would bank angle be limited to 20 deg or so based on radio altimeter?

[Dan Winterland]

Now if that was a 340, I'd say it was a typical AF landing!!!! :}

[Founder]

The picture is a fake... look at all the smoke in photoshop, it's the same color. Also look closely at the lines of color below the wheel that touches the ground. They are very much in-line while all other colors of the runway has pixels in them... this is the work of the blur tool in photoshop...

[panda-k-bear]

Oh good grief, if you think that's a genuine photo you really shouldn't be perusing a professional aviation website.

Now then, may I try to answer a few of these questions? I'm not saying one is right or wrong, what I'm saying is that soem of the differences in weight come from the design philosophy.

The A320 has a larger engine fan diameter than the 737 (any denomination) even though, nominally, they have the same CFM56 engines (the core of the -5 on the A320 is the same as the core on the -7 of the 737NG. The cores are the same, the fans aren't). Why is the fan diameter greater? Well, the -5 engine on the A320 has a higher bypass ratio than the -7 on the 737. That has 2 benefits - 1) the A320 engine has a lower specific fuel consumption and 2) the A320 engine runs cooler and so stays on the wing longer (greater EGT margin) which gives lower engine maintenance costs. So the A320 engines burn less fuel than the 737 engines and should cost less to maintain. The penalty is that the A320 needs a taller landing gear for ground clearance of the engines, so the gear is heavier than a 737 (weight penalty). The A320 has a greater fuselage diameter than the 737, so it will necessarily have more metal in it. It also has main landing gear doors to try to improve the aerodynamics (but they weigh something, of course) whereas the 737 wheels and wheel hubs sit partially in the airflow, so you get parisitic drag.

What you need to realise is that weight is not the be all and end all. The A320 is heavier than the 737. But the A320 engines burn less fuel and the aerodynamics are slightly better (yes the 737NG had a new wing, but Boeing were limited by the interface with the fuselage, as it didn't change, so they were forced to compromise by the constraints imposed on the spar positioning).

Swings and roundabouts that, at the end of the day, mean that they are both very close in fuel burn - and that's what counts these days.

I hope that's quite clear. And the company I work for has the A320 (and A319).
p-k-b

[TopBunk]

pkb

Useful background technical information, but it doesn't account for a 12 tonne (25%) weight difference, IMHO.

Could this unresolved weight difference maybe go some way to explaining the (apparent) large weight problems Airbus have with the A380? ... and yes, I know that all new aircraft are overweight by a margin suring development.

[monkey_wrench]

Remember all the other little extras like triple ADIRU, Brake Cooling fans, even heated foot pedals, etc. The options list for an Airbus is huge.
Apart from selecting HUD, different manufacturers for brakes, KGS or LBS for weights, max take off weights and thrust settings for the engines there isn't much to select in the way of additional kit with a 737NG unless you want a BBJ...

[panda-k-bear]

TopBunk

12 Tonne?

What?

Look at Flip Flop Flyer's post. Difference between an A320 and a 737-800 is of the order of 1 tonne. Where on earth does 12 tonnes come from? No way in hell!

I just dug out Boeing's estimates from when they wanted re-equip our fleet, and Airbus' estimates.

A320 OEW 43759kg
737-800 OEW 42829kg (without winglets, by the way - the gap closes when winglets are added).

Again, about 1 tonne difference, nowhere near the 12 tonnes you mentioned! Where on earth did you get that figure from?
p-k-b

[TopBunk]

PKB

If you choose to re-read my first post I compared the 737-400 to the A320. 12 tonnes difference between aircraft I have flown.

[panda-k-bear]

But in terms of performance, those 2 machines don't really compare, do they? They have roughly the same seating capacity (737-400 a little smaller). But the A320 offers substantially more range because it has a much bigger (more efficient) wing with much bigger fuel tanks contained therein. The 3000nm range criteria set for the A320 means that the bigger wing is necessary to accommodate the required fuel and I'm sure that's where you'll find the bulk of that weight difference that you quote - in the much bigger wing.

That along with, of course, the fuselage which is both longer (slightly) and wider (slightly). That adds up to quite a lot more metal in the fuselage as well.
p-k-b