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phllax
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Empty Weights between first and last off the line

Fri May 06, 2022 11:09 pm

With production of the 321ceo recently ending, I was wondering if there was any difference between the weight of the 1st 321-200 off the line Monarch received and the last one Delta received? Obviously advances in electronics and avionics have surely lightened the load, but what about advances in wiring and other parts during the 18 year production run?

Same could be asked for any make/model.
 
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77west
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Re: Empty Weights between first and last off the line

Sat May 07, 2022 8:33 pm

phllax wrote:
With production of the 321ceo recently ending, I was wondering if there was any difference between the weight of the 1st 321-200 off the line Monarch received and the last one Delta received? Obviously advances in electronics and avionics have surely lightened the load, but what about advances in wiring and other parts during the 18 year production run?

Same could be asked for any make/model.

An interesting topic - something else to consider is the increased MTOW over the years, could lead to a heavier structure due to strengthening etc. Maybe not as much on a narrowbody vs a widebody but still something to think about.
 
M564038
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Re: Empty Weights between first and last off the line

Sat May 07, 2022 9:49 pm

18 years? Surely you men 29(!) years?!

phllax wrote:
With production of the 321ceo recently ending, I was wondering if there was any difference between the weight of the 1st 321-200 off the line Monarch received and the last one Delta received? Obviously advances in electronics and avionics have surely lightened the load, but what about advances in wiring and other parts during the 18 year production run?

Same could be asked for any make/model.
 
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Francoflier
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Re: Empty Weights between first and last off the line

Sun May 08, 2022 4:10 am

From the very limited data I get from the fleets I'm familiar with, I get a feeling that most of the weight saving is done early in the production run, within the first few years. Empty weights tend to stabilise towards the end of the run.
I suppose it makes sense that the low hanging fruits would be picked first and when you still have loads of engineers working on the design. Afer that, the benefit/cost ratio probably decreases a lot.
 
Nicoeddf
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Re: Empty Weights between first and last off the line

Mon May 09, 2022 3:43 am

Francoflier wrote:
From the very limited data I get from the fleets I'm familiar with, I get a feeling that most of the weight saving is done early in the production run, within the first few years. Empty weights tend to stabilise towards the end of the run.
I suppose it makes sense that the low hanging fruits would be picked first and when you still have loads of engineers working on the design. Afer that, the benefit/cost ratio probably decreases a lot.


Interesting topic. And as usual, interesting insight from you. Thanks.
 
Avro7
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Re: Empty Weights between first and last off the line

Mon May 09, 2022 7:30 am

Seems like it would be hard to find an apples-to apples comparison in a lot of cases. Many manufacturers have different basic specifications like fuel tank configurations, number of lavatories and placement, and different versions of the same engine. It would be kind of rare for the first and last aircraft to come off the line to be built from the exact same blueprints.
 
Avro7
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Re: Empty Weights between first and last off the line

Mon May 09, 2022 7:32 am

Seems like it would be hard to find an apples-to apples comparison in a lot of cases. Many manufacturers have different basic specifications like fuel tank configurations, number of lavatories and placement, and different versions of the same engine. It would be kind of rare for the first and last aircraft to come off the line to be built from the exact same blueprints.
Last edited by Avro7 on Mon May 09, 2022 7:38 am, edited 2 times in total.
 
Avro7
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Re: Empty Weights between first and last off the line

Mon May 09, 2022 7:32 am

Seems like it would be hard to find an apples-to apples comparison in a lot of cases. Many manufacturers have different basic specifications like fuel tank configurations, number of lavatories and placement, and different versions of the same engine. It would be kind of rare for the first and last aircraft to come off the line to be built from the exact same blueprints.
 
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SAAFNAV
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Re: Empty Weights between first and last off the line

Mon May 09, 2022 1:01 pm

Avro7 wrote:
Seems like it would be hard to find an apples-to apples comparison in a lot of cases. Many manufacturers have different basic specifications like fuel tank configurations, number of lavatories and placement, and different versions of the same engine. It would be kind of rare for the first and last aircraft to come off the line to be built from the exact same blueprints.


Nothing personal, as double posting has happened to me on several posts.
But to use this opportunity: why does this keep happening?
 
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zkojq
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Re: Empty Weights between first and last off the line

Mon May 16, 2022 4:45 am

I'm curious about how similar the weights will be for sister aircraft coming off the production line next to one and other. Like if two aircraft are built to exactly the same spec how much will the weight vary between them? Are we talking about tens of kilos? 50? 100 would seem a lot, especially for a narrowbody.
 
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77west
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Re: Empty Weights between first and last off the line

Mon May 16, 2022 7:39 am

zkojq wrote:
I'm curious about how similar the weights will be for sister aircraft coming off the production line next to one and other. Like if two aircraft are built to exactly the same spec how much will the weight vary between them? Are we talking about tens of kilos? 50? 100 would seem a lot, especially for a narrowbody.


I would think for a narrowbody, up to a couple hundred kilos variance may not be out of the question, especially once painted.

For a widebody, I would think 500kg + variance may not be totally out of the question.

Here is a thread from way back: viewtopic.php?t=424503
 
gloom
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Re: Empty Weights between first and last off the line

Mon May 16, 2022 9:08 am

zkojq wrote:
I'm curious about how similar the weights will be for sister aircraft coming off the production line next to one and other. Like if two aircraft are built to exactly the same spec how much will the weight vary between them? Are we talking about tens of kilos? 50? 100 would seem a lot, especially for a narrowbody.


I've seen a +/- ZFW list of past 763 operator. There were offsets of +300/-250kg magnitude from reference.

Cheers,
Adam
 
ReverseFlow
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Re: Empty Weights between first and last off the line

Mon May 16, 2022 9:34 am

On a same configured aircraft built close to each other, the only differences in weight that I could think of is if you have more sealant applied everywhere or not.

Even if you had to oversize a hole/bolt combo you wouldn't be changing much weight.
 
M564038
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Re: Empty Weights between first and last off the line

Mon May 16, 2022 12:35 pm

Across many thousand parts it would mostly average out as well. Some slightly above, some slightly below.
As a layman in these matters:
The only factor causing a strong enough trend to do much, would be one team or shift doing major work like large amounts of adhesives or fasteners differently, at least as differently as could be within instructions given.

I have a hard time figuring 2 A320s or 737s in the same spec headed for the same company should vary by more than two digit kg. Hundreds of kilos sounds excessive, unless there had been some kind of official revision and spec change.
 
ReverseFlow
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Re: Empty Weights between first and last off the line

Mon May 16, 2022 8:17 pm

M564038 wrote:
Across many thousand parts it would mostly average out as well. Some slightly above, some slightly below.
As a layman in these matters:
The only factor causing a strong enough trend to do much, would be one team or shift doing major work like large amounts of adhesives or fasteners differently, at least as differently as could be within instructions given.

I have a hard time figuring 2 A320s or 737s in the same spec headed for the same company should vary by more than two digit kg. Hundreds of kilos sounds excessive, unless there had been some kind of official revision and spec change.


They wouldn't differ in the 100's.

And if a team/shift were to use different fastners or the likes you wouldn't be to drawing and you'd lose your production certificate pretty fast.
 
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zkojq
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Re: Empty Weights between first and last off the line

Tue May 17, 2022 3:40 am

gloom wrote:
zkojq wrote:
I'm curious about how similar the weights will be for sister aircraft coming off the production line next to one and other. Like if two aircraft are built to exactly the same spec how much will the weight vary between them? Are we talking about tens of kilos? 50? 100 would seem a lot, especially for a narrowbody.


I've seen a +/- ZFW list of past 763 operator. There were offsets of +300/-250kg magnitude from reference.

Cheers,
Adam


Thanks. And these were of exactly the same spec I assume?
 
gloom
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Re: Empty Weights between first and last off the line

Tue May 17, 2022 4:56 am

zkojq wrote:
Thanks. And these were of exactly the same spec I assume?


Yup, all within same specs.

Cheers,
Adam
 
GDB
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Re: Empty Weights between first and last off the line

Thu May 19, 2022 7:47 am

Going back and not even to a mass production aircraft, Concorde 204 (G-BOAC) was about a tonne heavier than last off the line 216 (G-BOAF).
The same applied to the French production aircraft.

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