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keesje
Posts: 14785
Joined: Thu Apr 12, 2001 2:08 am

RE: 787-3/8 4000 Lbs Overweight?

Wed May 31, 2006 7:04 pm

Quoting Boeing7E7 (Reply 49):
1. Extra seats = extra weight.

should have be limited impact, a few hundred pounds.

- less seat per passenger
- the heavy IFE seatboxes are usually 1 per 3 screens/passengers
2-4-2 -> 4 seatboxes (2 on the 4 seater)
3-3-3 -> 3 seat boxes (?!) a reason airlines preferred 3-3-3 over 2-4-3 & 2-5-2 in MD11/777.
 
widebodyphotog
Posts: 885
Joined: Wed Jun 30, 1999 9:23 am

RE: 787-3/8 4000 Lbs Overweight?

Wed May 31, 2006 8:15 pm

Quoting Keesje (Reply 50):
should have be limited impact, a few hundred pounds.

For the difference in 8a to 9a spec on 787-8 there is the following additions:

+9 economy seats

+2 business class seats

+2 first class seats

+1 lav unit

+3 galley units + carts(loaded)

+2 wardrobe units

Total weight ~3,000lbs



-widebodyphotog
 
Rheinbote
Posts: 1103
Joined: Sun May 21, 2006 9:30 pm

RE: 787-3/8 4000 Lbs Overweight?

Wed May 31, 2006 8:34 pm

Quoting Keesje (Reply 50):
the heavy IFE seatboxes are usually 1 per 3 screens/passengers

I dare to speculate that there will be no heavy seatboxes in the 787 cabin. Imagine wireless IFE and 'plug and play' power supply integrated into the seatrails. Only small seat power boxes remaining.

Eliminates ~600-800lbs of seat-to-seat cabling alone in a 787 size airplane.
 
atmx2000
Topic Author
Posts: 4301
Joined: Wed Oct 13, 2004 4:24 pm

RE: 787-3/8 4000 Lbs Overweight?

Wed May 31, 2006 9:04 pm

Quoting Keesje (Reply 50):
should have be limited impact, a few hundred pounds.

- less seat per passenger

Seats still have to support the same weight per passenger.

Quoting Widebodyphotog (Reply 51):
For the difference in 8a to 9a spec on 787-8 there is the following additions:

The floor map configuration capacity for the -8 of 237 passengers doesn't correspond to the design payload marked on the payload range chart, which is 242. Another one of Boeing's rushed mistakes?

Quoting Widebodyphotog (Reply 51):
+1 lav unit

I count 1 more lav unit in first and in business, for a total of 2F-3C-5Y compared to 1F-2C-5Y in the old config.

Quoting Widebodyphotog (Reply 51):
+3 galley units + carts(loaded)

I count 5 more galley slices. And what are the "W"'s near the rear? Wasted space?

Quoting Widebodyphotog (Reply 51):
Total weight ~3,000lbs

Have the exit doors just behind the wing been upgraded? They are marked as re-rated, and they look thicker on the floor plan.
 
DAYflyer
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Joined: Wed Sep 08, 2004 9:35 pm

RE: 787-3/8 4000 Lbs Overweight?

Wed May 31, 2006 10:16 pm

4,000 pounds on an aircraft of this size is not an insumountable obstical. Compared to what Airbus ran into on the A-380 and the amoun of weight reduction they will have to work on with the A-350 to get it anywhere near the 787, 4,000 lbs is small potatos.
 
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keesje
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Joined: Thu Apr 12, 2001 2:08 am

RE: 787-3/8 4000 Lbs Overweight?

Wed May 31, 2006 11:11 pm

Contrary to the 787 the A380 will seat fewer then the "typical 555"

Based on Widebodies assumptions this would mean a significantly lower OEW for the A380 then assummed in many threads. Is that correct?
 
DfwRevolution
Posts: 9316
Joined: Sat Jan 09, 2010 7:31 pm

RE: 787-3/8 4000 Lbs Overweight?

Wed May 31, 2006 11:20 pm

Quoting Keesje (Reply 55):
Based on Widebodies assumptions this would mean a significantly lower OEW for the A380 then assummed in many threads. Is that correct?

Depends...

In most cases, airlines are fitting less than 550 seats because a larger premium cabin which happen to be much heavier (per seat) than economy cabins. It's not quite a simple matter of saying an A380 at 480 seats has 13% less cabin related weight than a 550 seat A380.

Quoting Atmx2000 (Reply 53):

Have the exit doors just behind the wing been upgraded? They are marked as re-rated, and they look thicker on the floor plan.

Boeing indicated fairly early on that they wanted to avoid a 767/757 situation where carriers fit different types of emergency exits only to frustrate resale of the aircraft.

Standardized a full-size exit door would seem the most sensible option given the highly flexible nature of the 787's seating config.
 
Airportgal
Posts: 72
Joined: Wed Feb 09, 2005 2:23 pm

RE: 787-3/8 4000 Lbs Overweight?

Thu Jun 01, 2006 1:36 am

Quoting Picard (Reply 31):
The data in that .pdf contains a few errors, fuel capcity for 787-9 is wrong as is the 787-8 wing span.

check your facts.....
 
khobar
Posts: 1336
Joined: Fri Mar 17, 2006 4:12 am

RE: 787-3/8 4000 Lbs Overweight?

Thu Jun 01, 2006 3:25 am

Quoting Atmx2000 (Reply 53):
The floor map configuration capacity for the -8 of 237 passengers doesn't correspond to the design payload marked on the payload range chart, which is 242. Another one of Boeing's rushed mistakes?

I saw the word "preliminary" - that should answer your question.
 
widebodyphotog
Posts: 885
Joined: Wed Jun 30, 1999 9:23 am

RE: 787-3/8 4000 Lbs Overweight?

Thu Jun 01, 2006 4:17 am

Quoting Atmx2000 (Reply 53):
Have the exit doors just behind the wing been upgraded? They are marked as re-rated, and they look thicker on the floor plan.

Lol, the cabin data sheet I have does not correspond to the arrangement in the ACB...another Boeing oversight?...In any case the exit type was changed to acommodate a higher exit limit.

Quoting Keesje (Reply 55):
Based on Widebodies assumptions this would mean a significantly lower OEW for the A380 then assummed in many threads. Is that correct?

One thing that has to be remembered is that the seating units used by the Boeing and Airbus generic interior arrangements are often vastly different in terms of weight seating unit to seating unit. Even Y class seats with some newer IFE setups, and materials can be subtantially heavier than the generics. For first and business class, forget about it, they can be more than twice the weight...This is why you can end up with in-service OEW's that can be 20,000lbs heavier than manufacturer generic arrangements even when the airline specific configuration has fewer seats...

Given what carriers like SQ and EK are planning I would not hold my breath for lighter service ready A380's...



-widebodyphotog
 
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sunrisevalley
Posts: 5392
Joined: Tue Jul 06, 2004 3:26 am

RE: 787-3/8 4000 Lbs Overweight?

Thu Jun 01, 2006 9:10 am

On another forum our own Dalecary quotes Mike Bair as saying "a weight saving effort is underway because the aircraft is still a couple of percent above
our weight target, but below our guarantees".
Maybe this whole topic is a non-issue.
 
aeronut
Posts: 118
Joined: Tue Jan 31, 2006 8:41 am

RE: 787-3/8 4000 Lbs Overweight?

Thu Jun 01, 2006 9:25 am

Quoting Texfly101 (Reply 47):
Yes, and Yes. That's the case and what will happen. The first part of the model design, until validation during testing, will have had some increased margins due to the uncertainty of how disparate assemblies actually work together, both in manufacture and assembly. The partners that actually design and build the parts usually leave some extra materials in areas like webs, fillets, etc as they are both difficult to model and design, and it gives some room when B comes calling saying "gotta reduce weight, give me 2%". Actual flight will produce another round of refinements that will reduce weight but sometimes adds weight, so I would call it at worst to be a wash, but as Zvezda states, I agree with him.
I would expect the first group of airframes, I can't say how many that encompasses, to be at best, close to the target weight. I would expect the follow on airframes of the initial model to be on target for weight and performance. The next models will benefit from the lessons learned and will meet their target weight and performance, probably exceeding it, as has typically been the case for B's models. That was the way it went for 772LR and 773ER with their actual SFB to be even better than planned.



Quoting 787engineer (Reply 45):
Absolutely correct, there are several procedures for initiating change on parts that have already been released. Just because a part has been released doesn't mean Boeing can't go back and change it. How else do we continually make minor improvements to keep planes competitive? There are even plans for "re-releases" in which large numbers of parts can be replaced by newer releases. Early on re-releases are necessary because through testing many things may need to change.

You are absolutly correct, design continues to evolve even past design freeze.

AND Irtysh-Avia (Kazakhstan)">IT IS EXPENSIVE TO TAKE WEIGHT OUT OF FILLET RADIUS AND WEBS AFTER MONEY HAS BEEN SPENT ON TOOLING AND PARTNERS HAVE COMMITTED TO GUARANTEED WEIGHTS. In my career, I have yet to see this happen unless an overweight issues threatens the very existance of the program.

My experience in airframe testing is usually used for validation and not for optimization.

If I left extra material in my designs, I'd be a terrible aerospace engineer and my weights engineer would be very mad.

I'd love to have the opportunity to work for Boeing and see how the experts do it  Smile
 
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keesje
Posts: 14785
Joined: Thu Apr 12, 2001 2:08 am

RE: 787-3/8 4000 Lbs Overweight?

Fri Jun 09, 2006 11:59 pm

Quoting Atmx2000 (Thread starter):

You were right.

If the design empty weight of the 787-8 is lbs 216.5t,

the 787 is at this stage 2.5% or about lbs 5.4 tons overweight

Now confirmed by Boeing / Mike Bair.

"We will meet all the commitments we made to our customers, even if [the weight] doesn't get any better," Bair said.

It seems he keeps open if the weight will be reduced.

http://seattletimes.nwsource.com/htm...ology/2003049536_dreamliner09.html
 
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Stitch
Posts: 27745
Joined: Wed Jul 06, 2005 4:26 am

RE: 787-3/8 4000 Lbs Overweight?

Sat Jun 10, 2006 12:02 am

Well Airbus has said that even with the extra weight the A380 ended up having to carry at delivery, she will still meet her performance targets. So I see no reason not to give Boeing the same benefit of the doubt should they be unable to address the weight issue prior to delivery. *shrug*
 
BoomBoom
Posts: 2459
Joined: Fri Nov 04, 2005 2:26 am

RE: 787-3/8 4000 Lbs Overweight?

Sat Jun 10, 2006 12:12 am

Quoting Keesje (Reply 62):

"We will meet all the commitments we made to our customers, even if [the weight] doesn't get any better," Bair said.

Of course, you left out some key information in your "quote", intentionally, no doubt.

While Bair admitted the 787 is still about 2.5 percent over its target weight, he said that target includes an extra safety margin beyond what's needed to meet the fuel-efficiency promises made to airlines.

"We will meet all the commitments we made to our customers, even if [the weight] doesn't get any better," Bair said.


Remember Boeing usually exceeds performance specs, maybe they won't be able to do that with the 787, they will only be able to meet them.
 
airmailer
Posts: 478
Joined: Thu Jun 01, 2006 4:28 am

RE: 787-3/8 4000 Lbs Overweight?

Sat Jun 10, 2006 12:24 am

Quoting Rheinbote (Reply 19):
Whatever, any remaining potential for weight reductions, if needed, can be cashed in with -9 and -10, and then transitioned back to later versions of the -8.

Not that I build airplanes or anything, but I would expect this to be a very likely scenario to play out.
(especially since they now have the -10 in the picture.)
 
Ken777
Posts: 10203
Joined: Thu Mar 11, 2004 5:39 am

RE: 787-3/8 4000 Lbs Overweight?

Sat Jun 10, 2006 12:41 am

If each engine is 500 to 1,000 pounds over target right now then they and the electrical systems will probably offer the greatest potential for weight savings.

I would bet, however, that the performance in terms of fuel economy will be far more important a target for the airlines and Boeing seems to be within the commitments they have made to the airlines. If Boeing can improve even more on fuel economy I think that missing the optimum OEW will not be very important in the grand scheme of things.
 
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FLALEFTY
Posts: 1185
Joined: Tue Jan 31, 2006 11:33 am

RE: 787-3/8 4000 Lbs Overweight?

Sat Jun 10, 2006 1:15 am

Having been in the aerospace business for nearly 20 years, I'd say being less than 5% over the target weight budget at preliminary design release shows pretty good performance by Boeing and their subs. I've seen other programs struggle with weight issues beyond low-rate production deliveries.

There is no "magic" in meeting a weight budget - the designers of every component on the aircraft will work to contribute their share in reaching the design goals.
 
atmx2000
Topic Author
Posts: 4301
Joined: Wed Oct 13, 2004 4:24 pm

RE: 787-3/8 4000 Lbs Overweight?

Sat Jun 10, 2006 2:11 am

Quoting Keesje (Reply 62):
You were right.

If the design empty weight of the 787-8 is lbs 216.5t,

the 787 is at this stage 2.5% or about lbs 5.4 tons overweight

Now confirmed by Boeing / Mike Bair.

"We will meet all the commitments we made to our customers, even if [the weight] doesn't get any better," Bair said.

It seems he keeps open if the weight will be reduced.

I estimated the OEW increase from the payload decrease, which was only 4000 lbs, or 1.8t. That is less 0.8% of MTOW, and only around 1.7% of OEW. The payload range chart likely reflects the OEW change for what appears to be standard 9Y configuration, and not any changes due to missed weight specifications. It makes no sense for Boeing to adjust those numbers until they know they won't get to target weight for the aircraft without cabin. But they have to accurately reflect the payload-range for the 9Y configuration if they are going to market it as a standard.

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