A380 wing snaps before design load limits..

[joe_pilot]

Here's why the A380 will fail: Too small a market, too ugly an airplane. Name for me one ugly airplane that was ever successful. You can't.

I completely agree about the 380, but the SkyVan/Shorts was/is one UGLY(but so beautiful) airplane. I would call it successful.

 

[LJDRVR]

Nothing ugly about the shorts at all.

 

[Rally]

So from what I see the United interpreted the Position and Hold as a takeoff clearance? Or am I missing something.

 

[EagleRJ]

"This is within 3% of the 1.5 target, which shows the accuracy of the FEM.”

Within 3% ON THE WRONG SIDE!!!

Part 25 specifies not "about 1.5 times design load" or "1.5 times design load- +/- 5%", it states:

<H5>§ 25.303 Factor of safety.

Unless otherwise specified, a factor of safety of 1.5 must be applied to the prescribed limit load which are considered external loads on the structure. When a loading condition is prescribed in terms of ultimate loads, a factor of safety need not be applied unless otherwise specified.
[Amdt. 25–23, 35 FR 5672, Apr. 8, 1970]

In other words, a wing that holds at least 1.5x the design load passes under Part 25. A wing that holds only 1.47x design load FAILS!

The way I see it, Airbus has two choices: it can redesign the wing and re-test a new article to failure, or it can certify the aircraft at a lower maximum weight (despite the fact that the aircraft is already over its design weight and is unable to carry the payload Airbus promised).

....and the A380 has yet to pass the 90-second passenger evacuation drill, a test some experts think it doesn't have enough doors to pass! No pass- no pax.
What a disaster.

 

[mzaharis]

Within 3% ON THE WRONG SIDE!!!

Part 25 specifies not "about 1.5 times design load" or "1.5 times design load- +/- 5%", it states:

</H5>In other words, a wing that holds at least 1.5x the design load passes under Part 25. A wing that holds only 1.47x design load FAILS!

The way I see it, Airbus has two choices: it can redesign the wing and re-test a new article to failure, or it can certify the aircraft at a lower maximum weight (despite the fact that the aircraft is already over its design weight and is unable to carry the payload Airbus promised).

....and the A380 has yet to pass the 90-second passenger evacuation drill, a test some experts think it doesn't have enough doors to pass! No pass- no pax.
What a disaster.

But FAR 25.305 follows up with:

When analytical methods are used to show compliance with the ultimate load strength requirements, it must be shown that—

(1) The effects of deformation are not significant;
(2) The deformations involved are fully accounted for in the analysis; or
(3) The methods and assumptions used are sufficient to cover the effects of these deformations.

I suggest that they may be able to go with (2) and (3), and argue that their FEM is close enough (with a .03 fudge factor ) to qualify a redesigned structure without building a test article.

If not, they're going to have a big bill for the new test article and significant project delay, which doesn't do any good for their ROI.

I think that their plan was to do the evac test with some ridiculous number of passengers (800) so that they would not need to redo the test if they ever sold a short-haul single-class (think ANA 747SR) version. If they get close to service, I'd imagine that they could pop off a test with "only" 500-550 to get the thing into revenue service with the likely number of seats most airlines will use.

 

[habubuaza]

So from what I see the United interpreted the Position and Hold as a takeoff clearance? Or am I missing something.

Not sure, but definately some sort of runway incursion

 

[EagleRJ]

But FAR 25.305 follows up with:

When analytical methods are used to show compliance with the ultimate load strength requirements, it must be shown that—

(1) The effects of deformation are not significant;
(2) The deformations involved are fully accounted for in the analysis; or
(3) The methods and assumptions used are sufficient to cover the effects of these deformations.

But when allowable deformation occurs in a structure, it is still capable of carrying the rated load. In this case, the wing broke.

I'm not sure about it, but I don't think Airbus is permitted to use a computer stress analysis to validate the wing structure- it has to be an actual test.
Airbus might try sneaking around the rules on this matter too. I heard that regarding the evacuation, they originally tried to certify the A380 based on "approximations" with existing data, using A330 data for the upper deck, and A300 data for the lower deck, and that idea was promptly shot down. It could be that they were simply trying to save the cost of a full-up test, or it could be that they too are worried about the A380 being able to pass.

 

[joe_pilot]

Nothing ugly about the shorts at all.

What!?? The Shorts is one of the ugliest airplanes ever built. Of course it IS so ugly, it is good looking.

 

[NoPax]

But FAR 25.305 follows up with...

Isn't the A380 being first certified under JAR-land rules and regs....what exactly do those say? It may be the same - I don't know. Lots of interesting info though.

and the A380 has yet to pass the 90-second passenger evacuation drill, a test some experts think it doesn't have enough doors to pass! No pass- no pax.
What a disaster.

No pax wouldn't be a total disaster...just a big double-decker freighter

 

[NoPax]

What!?? The Shorts is one of the ugliest airplanes ever built. Of course it IS so ugly, it is good looking.

An airplane built by ship-builders (and it still isn't waterproof from what I've been told)

 

[EuroWheenie]

Just a few corrections:

A/ The wing ain't French, it's British. Not the sort of people know to surrender.

B/ The A380 is already a commercial success, with 159 orders to date. Ugly or not. Check how many orders the 747 had 9 months before entering revenue service.

C/ Why no US airlines have bought them? Well, probably because the only viable candidates don't have any money!

D/ The evac test will be interesting. I have no doubt it will pass, eventually. Airbus will try to do it with max. pax load, which is in the 850ish range. Please bear in mind that no airline are planning to have more than 550 seats, and it will easily evac 550 people in 90 seconds. It's got, what, 18 doors? If the 747 can evac 490 using 5 doors, why shouldn't the A380 do 850 with 9? Oh, and the slides are American in design and manufacture!

As for the wing, I have no worries whatsoever that it will meet design and certification criteria.

 

[LJDRVR]

With a wing redesign coming, plus an additional static test, 159 airframes is far from the break even point.

 

[EagleRJ]

B/ The A380 is already a commercial success, with 159 orders to date. Ugly or not. Check how many orders the 747 had 9 months before entering revenue service.

But the rate of new orders has tapered off to near zero. Many airlines with existing orders and options appear to be having second thoughts, due to A380 performance shortfalls, operational issues, and the announcement of the B747-800. I don't know where the break-even is, but I don't know if you can pronounce the A380 a "commercial success" with 159 orders and none yet in revenue service. The 747 family is considered a success, but Boeing has built more than 1300 of them.

C/ Why no US airlines have bought them? Well, probably because the only viable candidates don't have any money!

Right, like Airbus never "gives" aircraft to operators that are in precarious financial condition, to boost their sales totals? Remember Independence Air?
More likely, US airlines don't see a need for an aircraft that can only fly into a handful of airports and is too big for any of their markets. It appears that they are happy with their 747s and 777s.

D/ The evac test will be interesting. I have no doubt it will pass, eventually. Airbus will try to do it with max. pax load, which is in the 850ish range. Please bear in mind that no airline are planning to have more than 550 seats, and it will easily evac 550 people in 90 seconds. It's got, what, 18 doors? If the 747 can evac 490 using 5 doors, why shouldn't the A380 do 850 with 9? Oh, and the slides are American in design and manufacture!

The A380 has 16 exits, and the 747 has 12. The main problem is that while the 747 has just a small first-class area on the second deck (with two dedicated exits), the A380 has a whole passenger deck. There are concerns with the height of those escape slides, as well as the possibility that passengers will use the stairs and overload lower level exits (as has happened in previous 747 evacuations). Link

 

[Golden Falcon]

The Shorts aka the "Irish Concorde" is a beautiful airplane

 

[dseagrav]

Name for me one ugly airplane that was ever successful.

The JU-87.