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Could The MD-11 Problems Happen Today?  
User currently offlineAirEMS From United States of America, joined May 2004, 684 posts, RR: 3
Posted (7 years 1 month 2 weeks 4 days 22 hours ago) and read 5332 times:

Could the performance problems of the MD-11 happen today with all of the computer technology and tons of wind tunnel testing that all potential and launched designs go through?

Could the A380 / 350 or the B 787 / 748 have performance problems that were not found during the planning or computer / wind tunnel testing.

Sorry if this has been put out before and remember if you flame please flame with care...  duck 

-Carl


If Your Dying Were Flying
33 replies: All unread, showing first 25:
 
User currently offlineLTU932 From Germany, joined Jan 2006, 13864 posts, RR: 50
Reply 1, posted (7 years 1 month 2 weeks 4 days 20 hours ago) and read 5214 times:

It certainly is possible. Maybe the aircraft is on spec during windtunnel testing, but what if the performance problem is related to a part that's not built by Boeing or Airbus, like the engines? I mean, weren't some of the MD-11 problems not related to the engines not delivering the required performance as well?

User currently offlineConcordeBoy From , joined Dec 1969, posts, RR:
Reply 2, posted (7 years 1 month 2 weeks 4 days 17 hours ago) and read 4992 times:

...the M11's problems stemmed mostly from its outdated/compromised (relative to upcoming competitors) wing design, and its CoG/trim issues.

User currently offlineUAL747 From , joined Dec 1969, posts, RR:
Reply 3, posted (7 years 1 month 2 weeks 4 days 17 hours ago) and read 4987 times:

Any new aircraft can experience "teething" problems. One aircraft that comes to mind is the A340-600 and somewhat the -500.

Supposedly, the A346 original variants did not live up to performance specifications, thus Airbus introduced the HGW variant. Also, I've heard that the A346 is nose heavy, meaning that there a balance issue in some sense where the forward fuselage is a bit heavy. Now, I heard that on a.net and I don't have anything to back it up, but there you go.

For the -500, it's going to be outclassed and outperformed by the 772LR's lower fuel burn and cargo capacity.

UAL


User currently offlineConcordeBoy From , joined Dec 1969, posts, RR:
Reply 4, posted (7 years 1 month 2 weeks 4 days 15 hours ago) and read 4811 times:

Quoting UAL747 (Reply 3):
For the -500, it's going to be outclassed and outperformed by the 772LR's lower fuel burn and cargo capacity.

...and cabin width, and range, and payload/density capability, and speed, and...............


User currently offlineTrijetsRMissed From United States of America, joined Oct 2006, 2331 posts, RR: 7
Reply 5, posted (7 years 1 month 2 weeks 4 days 13 hours ago) and read 4644 times:

Quoting AirEMS (Thread starter):
Could the A380 / 350 or the B 787 / 748 have performance problems that were not found during the planning or computer / wind tunnel testing.

The A380's problems and delays make the MD-11 seem relatively minimal in comparison.

Quoting LTU932 (Reply 1):
I mean, weren't some of the MD-11 problems not related to the engines not delivering the required performance as well?

Yes, during flight testing it became known that the CF6 and PW4460 experienced excessive fuel burn. The PW4462 solved most of these problems and added an 8% increase in range on the later PIP models.

The other major problem was the airframe was heavier and more drag-prone than expected. This was fixed with composite panels and a larger No.2 engine intake.



There's nothing quite like a tri-jet.
User currently offlineReins485 From United States of America, joined Jul 2005, 136 posts, RR: 0
Reply 6, posted (7 years 1 month 2 weeks 4 days 13 hours ago) and read 4636 times:

Quoting ConcordeBoy (Reply 2):
the M11's problems stemmed mostly from its outdated/compromised (relative to upcoming competitors) wing design, and its CoG/trim issues.

Agreed, my dad use to fly to the MD-11 and they use to play a game to see if they could hand fly it and keep it at a level altitude, which was close to impossible he said and they would end up oscillating up and down . I don't remember how bad it would get.


User currently offlineTrijetsRMissed From United States of America, joined Oct 2006, 2331 posts, RR: 7
Reply 7, posted (7 years 1 month 2 weeks 4 days 11 hours ago) and read 4587 times:

Quoting Reins485 (Reply 7):
Quoting ConcordeBoy (Reply 2):
the M11's problems stemmed mostly from its outdated/compromised (relative to upcoming competitors) wing design, and its CoG/trim issues.

Agreed, my dad use to fly to the MD-11 and they use to play a game to see if they could hand fly it and keep it at a level altitude, which was close to impossible he said and they would end up oscillating up and down . I don't remember how bad it would get.

While the trim characteristics may have been undesirable, it did not contribute much to a loss of sales or the inability to initially meet range expectations during flight testing, which is what we're talking about here. The tail-heavy COG issue has been debated on here at nauseam. And while in hindsight a better wing design would have benefited the aircraft, it was not one of the main issues in 1990.



There's nothing quite like a tri-jet.
User currently offlineRoseFlyer From United States of America, joined Feb 2004, 9511 posts, RR: 52
Reply 8, posted (7 years 1 month 2 weeks 4 days 10 hours ago) and read 4553 times:

It could happen, but I think performance limitations would be known earlier on in the design stage. You should remember that the MD-11 had very very little computer support in the design process. They couldn't simulate the different systems anywhere near as well as they can today. Furthermore the testing process done for each of the components was no where near as good as it is today. So performance problems would be known about earlier on in the design process so corrective action could be taken earlier. I don't think we would see as much of a surprise as we did with the MD11.

But that doesn't mean that design problems can't happen. Technology is getting better, but planes are getting more complex and technology is always being pushed.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlineWILCO737 From Greenland, joined Jun 2004, 8971 posts, RR: 76
Reply 9, posted (7 years 1 month 2 weeks 4 days 5 hours ago) and read 4512 times:
AIRLINERS.NET CREW
HEAD MODERATOR

Hi guys,

I just come out of the sim of the MD11F and I never experienced any performance problems! I mean, in the freighter you can take 94 tons of freight with you and still fly FRA-ORD nonstop, which isnt too bad. Even the take off performance isnt bad! Well, in NBO of course you cannot take off with MTOW (its reduced to roughly 275tons iso 286 tons).
One engine out isnt much big of a deal as well. normal approach, using flaps 35 and not 50 anymore, but normal go around procedure. 2 engine out will be a little more difficult, but under certain conditions you can still fly a go around (!!!) with only ONE engine remaining! Read carefully: under certain conditions... but it is possible! I did it in the sim several times and it worked...
Yes, the wing load is really high and the normal approach speed at MLAW is 168KIAS... which is a lot higher than most modern airliner. And of course the FAR required field length is increased as well... But still, the climb performance and the go around performance was/ is quite impressive...

WILCO737 (MD11F)
 airplane 



It it's not Boeing, I am not going.
User currently offlineMoo From Falkland Islands, joined May 2007, 3884 posts, RR: 5
Reply 10, posted (7 years 1 month 2 weeks 4 days 3 hours ago) and read 4485 times:

Quoting TrijetsRMissed (Reply 6):

The A380's problems and delays make the MD-11 seem relatively minimal in comparison.

Thats a totally different discussion - the A380 issues are not performance related.


User currently offlineCosmicCruiser From United States of America, joined Feb 2005, 2255 posts, RR: 15
Reply 11, posted (7 years 1 month 2 weeks 4 days ago) and read 4434 times:

Quoting WILCO737 (Reply 10):
I just come out of the sim of the MD11F and I never experienced any performance problems!



Quoting WILCO737 (Reply 10):
Even the take off performance isnt bad!

Your complete post was accurate and well stated. The T/O perf. even at MTOGW is very good and I've seen days at lighter wgts (CDG-FRA) where the vert. spd tape will be pegged. It's impressive!

Quoting TrijetsRMissed (Reply 8):
The tail-heavy COG issue has been debated on here at nauseam

If you're referring to the OLD (very old) data base stab problems you're right that's been run into the grd and doesn't exist anyway anymore. And I don't think that was a CG prob. Wasn't it more of an LSAS prob? Tail fuel mgt. will give you an aft CG for cruise which improves range.


Quoting Reins485 (Reply 7):
my dad use to fly to the MD-11 and they use to play a game to see if they could hand fly it and keep it at a level altitude, which was close to impossible he said and they would end up oscillating up and down .

It's not so bad now BUT I probably wouldn't want to do it for very long. But hey I remember in my 727 days hand flying 2/3 the way across the country because the A/P was deferred and the F/O and I would swap up flying the thing every 30 min. because it was a lot of work. It certainly wasn't like trimming up the old beech and letting it ride!
 Wink
Big version: Width: 834 Height: 667 File size: 48kb


User currently offlineWILCO737 From Greenland, joined Jun 2004, 8971 posts, RR: 76
Reply 12, posted (7 years 1 month 2 weeks 3 days 22 hours ago) and read 4359 times:
AIRLINERS.NET CREW
HEAD MODERATOR

Quoting CosmicCruiser (Reply 12):
Your complete post was accurate and well stated. The T/O perf. even at MTOGW is very good and I've seen days at lighter wgts (CDG-FRA) where the vert. spd tape will be pegged. It's impressive!

Phew Thank god I had it right, otherwise I have to give back my MD11 type rating  Wink

WILCO737 (MD11F)
 airplane 



It it's not Boeing, I am not going.
User currently offlineJwenting From Netherlands, joined Apr 2001, 10213 posts, RR: 18
Reply 13, posted (7 years 1 month 2 weeks 3 days 21 hours ago) and read 4348 times:

Ah, but the "problem" of course is that it has too much power (as compared to the A340-200 and -300)  Smile


I wish I were flying
User currently offlineTrijetsRMissed From United States of America, joined Oct 2006, 2331 posts, RR: 7
Reply 14, posted (7 years 1 month 2 weeks 2 days 10 hours ago) and read 4132 times:

Quoting WILCO737 (Reply 10):

Great post WILCO, this aircraft is more than capable, contrary to popular belief.

Quoting Moo (Reply 11):
Thats a totally different discussion - the A380 issues are not performance related.

I would consider weight to be completely relevant with this discussion. It is performance related and two years later it is still delayed..

Quoting CosmicCruiser (Reply 12):
If you're referring to the OLD (very old) data base stab problems you're right that's been run into the grd and doesn't exist anyway anymore.

Yes and you are correct.



There's nothing quite like a tri-jet.
User currently offlineMoo From Falkland Islands, joined May 2007, 3884 posts, RR: 5
Reply 15, posted (7 years 1 month 2 weeks 2 days 6 hours ago) and read 4091 times:

Quoting TrijetsRMissed (Reply 15):

I would consider weight to be completely relevant with this discussion. It is performance related and two years later it is still delayed..

The weight increase is offset by the better than expected engine performance, meaning that the A380s performance is as expected.

None of the big vocal purchasers (SIA, Qantas, EK) have voiced issues with the performance figures of the aircraft, therefor I still don't believe this is relevent for this discussion - so far there have been no demonstratable performance issues with the A380.


User currently offlineAeroweanie From United States of America, joined Dec 2004, 1607 posts, RR: 52
Reply 16, posted (7 years 1 month 2 weeks 2 days ago) and read 4017 times:
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Quoting ConcordeBoy (Reply 2):
...the M11's problems stemmed mostly from its outdated/compromised (relative to upcoming competitors) wing design, and its CoG/trim issues.

No, this was not the cause of the performance shortfalls!!!

When a manufacturer considers buying an engine, the engine manufacturer supplies a computer program that simulates the engine performance, called an engine deck. Typically, Boeing and Airbus audit these decks, using their experience, and make them a little more conservative. Douglas at the time didn't have a lot of money, so they decided to trust the engine manufacturers and not audit the decks. As expected, the decks were optimistic and in flight test, they were found to burn 2-5% more fuel than the decks claimed. Douglas then scrambled to produce aerodynamic fixes that ended up partly recovering this deficit.


User currently offlineCloudy From , joined Dec 1969, posts, RR:
Reply 17, posted (7 years 1 month 2 weeks 1 day 22 hours ago) and read 3978 times:

Quoting WILCO737 (Reply 10):
Hi guys,

I just come out of the sim of the MD11F and I never experienced any performance problems!

Nobody is claiming the MD11 ever was a poor performer from a pilot's perspective. It had adequate thrust and handles well enough, The problem was that the payload/range was less then promised and the fuel burn was more than promised - at least initially.


User currently offlineWILCO737 From Greenland, joined Jun 2004, 8971 posts, RR: 76
Reply 18, posted (7 years 1 month 2 weeks 1 day 22 hours ago) and read 3968 times:
AIRLINERS.NET CREW
HEAD MODERATOR

Quoting Cloudy (Reply 18):
Nobody is claiming the MD11 ever was a poor performer from a pilot's perspective. It had adequate thrust and handles well enough, The problem was that the payload/range was less then promised and the fuel burn was more than promised - at least initially.

I just wanted to clear this up! Because I heard about complains about the performance... and I never experienced any... I am really impressed about he performance...

WILCO737 (MD11F)
 airplane 



It it's not Boeing, I am not going.
User currently offlineVmabuck From United States of America, joined Jun 2007, 7 posts, RR: 0
Reply 19, posted (7 years 1 month 2 weeks 1 day 12 hours ago) and read 3817 times:

I see a lot of under spec situations from the Airlines. I see parts fail prematurely due to too much stress/heat/current loads. At the moment it seems to be the actuator world that is affected the most; for the last few months anyway. Well minus a few power panels here and there (AAIB Bulletin S2-2007)

Another trend I notice is how quickly someone like Airbus or Boeing will put out a Service Bulletin to focus attention on the OEM. When you go to someone and ask them to build a part to your spec, you should be willing to step up and admit your responsibility in the situation.



Happiness is Vectored Thrust!
User currently offlineVmabuck From United States of America, joined Jun 2007, 7 posts, RR: 0
Reply 20, posted (7 years 1 month 2 weeks 1 day 12 hours ago) and read 3804 times:

Quoting Vmabuck (Reply 20):
I see a lot of under spec situations from the Airlines.

Edit*

I see a lot of under spec situations from the Aircraft manufacturers.



Happiness is Vectored Thrust!
User currently offlineTrijetsRMissed From United States of America, joined Oct 2006, 2331 posts, RR: 7
Reply 21, posted (7 years 1 month 2 weeks 8 hours ago) and read 3642 times:

Quoting Cloudy (Reply 18):
The problem was that the payload/range was less then promised and the fuel burn was more than promised - at least initially.

It is unfortunate how badly the MD-11 is looked upon in terms of payload/range. Consider this, in 1995 when both the A343 and 772 where in full production, the MD-11 greatly outperformed both of its competitors. The 777 may have been the a media darling, but the 772A models lack the MD-11ER by 2,000nm in range! The A343 also lacked in range and was far slower. This assumes each airliner is loaded with approx 300 passengers, give or take a little depending on the type. Not to mention the tri-jet has ample cargo space.

Since then, both the 777 and A340 series have improved variants, which surpass the MD-11. But for its time the MD-11 held its own. And who's to say if production and support for the type continued that newer versions of the MD-11 wouldn't have continued that trend?



There's nothing quite like a tri-jet.
User currently offlineXT6Wagon From United States of America, joined Feb 2007, 3392 posts, RR: 4
Reply 22, posted (7 years 1 month 1 week 6 days 11 hours ago) and read 3560 times:

Quoting Moo (Reply 10):
Thats a totally different discussion - the A380 issues are not performance related.

not being certifed, no production certificate are just minor performance issues the A380 has had after it was schedualed to be delivered.

Also if you think "IFE" wiring is the cause of the delay, I got some ocean front property in Tibet to sell you.


User currently offlineMoo From Falkland Islands, joined May 2007, 3884 posts, RR: 5
Reply 23, posted (7 years 1 month 1 week 6 days 4 hours ago) and read 3523 times:

Quoting XT6Wagon (Reply 22):

not being certifed, no production certificate are just minor performance issues the A380 has had after it was schedualed to be delivered.

If those are performance related in the context that we are discussing with regard to the MD-11, Im the King of the United British Colonies of the North Americas.

Of course you can open up the context as wide as you personally like to attempt to bring the A380 into this.

Quoting XT6Wagon (Reply 22):
Also if you think "IFE" wiring is the cause of the delay, I got some ocean front property in Tibet to sell you.

Having *personally* seen the work going on in Hamburg, unless you have significant evidence that isnt someones blog somewhere, Im going to have to call bullsh*t on this one.


User currently offlineDougloid From , joined Dec 1969, posts, RR:
Reply 24, posted (7 years 1 month 1 week 5 days 22 hours ago) and read 3471 times:

Quoting AirEMS (Thread starter):
Could the performance problems of the MD-11 happen today with all of the computer technology and tons of wind tunnel testing that all potential and launched designs go through?

Define performance problems. What were they, and how do you know this? Please do not cite wikipedia.

Quoting TrijetsRMissed (Reply 5):
oting AirEMS (Thread starter):
Could the A380 / 350 or the B 787 / 748 have performance problems that were not found during the planning or computer / wind tunnel testing.

The A380's problems and delays make the MD-11 seem relatively minimal in comparison.

Correct. I was there. I spent a lot of time crawling around inside 447.

Quoting TrijetsRMissed (Reply 5):
Yes, during flight testing it became known that the CF6 and PW4460 experienced excessive fuel burn. The PW4462 solved most of these problems and added an 8% increase in range on the later PIP models.

The other major problem was the airframe was heavier and more drag-prone than expected. This was fixed with composite panels and a larger No.2 engine intake

The flight manual was revised to trim the aircraft for a more rearward flight cg. This is more efficient and yielded better fuel economy, Unfortunately all those performance tweaks came about after Singapore cancelled the order for 20.

Quoting TrijetsRMissed (Reply 7):
While the trim characteristics may have been undesirable, it did not contribute much to a loss of sales or the inability to initially meet range expectations during flight testing, which is what we're talking about here. The tail-heavy COG issue has been debated on here at nauseam. And while in hindsight a better wing design would have benefited the aircraft, it was not one of the main issues in 1990.



Quoting Moo (Reply 10):
Quoting TrijetsRMissed (Reply 6):

The A380's problems and delays make the MD-11 seem relatively minimal in comparison.

Thats a totally different discussion - the A380 issues are not performance related.

The only reason you say that is because there's no A380 performance numbers to assess yet-there ARE a lot of press releases from Airbus though. The information's being carefully controlled and until there are concrete numbers from operators it would be wise to take anything the manufacturer says with a grain of salt about the size for the ones we put out for cattle.

There's a lot of 'performance' misinformation about the MD11 and its predecessor the DC10 in this forum and elsewhere. One time I was going cross country with the old lady and I ask here "So honey, what do you think about the DC10?" She says "Oh, I wouldn't fly on one, everyone knows they're death traps." So I say, "OK then, what about this airplane and this flight? " She says "Oh this is much different-quiet and smooth." I say, "This is a DC10 we've been riding in for the last three hours".


25 Moo : Both EK and SIA have stated (EK on more than one occasion) that they are happy with the performance of the aircraft - so unless they are being lied t
26 Starlionblue : Classic. It can be argued that some accidents make a type safer since improvements are made based on what went wrong. And even without such events, t
27 Dougloid : I could believe that. Boeing let the line bleed to death. Saying someone's allegedly happy (whatever that means) is not a substitute for performance
28 Moo : I made no statement about me personally having performance figures, however I take the public statements (no alledgedly here, the comments came from
29 Starlionblue : Hehe. But what about: "How do you tell a communist? Well, it's someone who reads Marx and Lenin. And how do you tell an anti-Communist? It's someone
30 Post contains images WILCO737 : As you said: only a rumour... WILCO737 (MD11F)
31 Dougloid : What you said more or less was EK and SIA are happy so unless GE and RR are lying to them everything's just peachy keen with A380 performance. Aircra
32 Post contains images TrijetsRMissed : Indeed, that was a significant blow to the MD-11 program, from which it never recovered. I don't think it's any coincidence that the MD-11ER was laun
33 XT6Wagon : yes its clearly not a performance issue that for the first year and a half after the delivery date in the contract its managed to haul $0 of revenue.
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