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Pls Explain For The A340s Underperformance  
User currently offlineJaemz From , joined Dec 1969, posts, RR:
Posted (14 years 7 months 1 week 4 hours ago) and read 1045 times:

Alright, this is a genuine, innocent question about the A340s. I see alot of folks talking about its under performance, things like it climbs only cos Earth is round etc...
Are those the results of weak engines or their structural design, maybe its wings?
If so, is this underperformance generic to the 330s as well?

7 replies: All unread, jump to last
 
User currently offlineSabena From Belgium, joined Aug 1999, 52 posts, RR: 5
Reply 1, posted (14 years 7 months 1 week 3 hours ago) and read 862 times:

I've also heard many critics... Even Air france operations chiefs seem to be critical about the A340.
That's the reason why Singapore decided to keep the 777-300 instead of their A340-300E Celestar. They mentioned they were clearly disapointed with their A340's parformances.
Nevertheless, the A340 is well sold... But as airline executive I would rather choose the 777 !!!


User currently offlinePratt-Whitney From , joined Dec 1969, posts, RR:
Reply 2, posted (14 years 7 months 6 days 19 hours ago) and read 834 times:

The CFM56-5C is not powerful enough to effectively power the plane, on take off, climb, and cruise. They were only forced to use the CFM after IAE canceled their V2500 superfan program in 1988 (??--around that time). The superfan was more powerful and efficent. When it was cancelled the CFM was what was left. If you'll notice the newer A340s have Much more powerful engines. (Trent 500s).

I don't believe the A330 has these problems.

If I were an airline executive, I'd take the 777 standard series over the A340 200/300 and the A340 500/600 over the 777X.


User currently offlineTEDSKI From , joined Dec 1969, posts, RR:
Reply 3, posted (14 years 7 months 6 days 15 hours ago) and read 812 times:

I agree with you 100% that the A340 200 & 300 series CFM56 engines are underpowered and maxed out. That engine is only good for such aircraft like the 737, KC-135R, DC-8 & A320 family, the RR Trent 500 is the best powerplant to put on the new 500 & 600 series A340. Are the engines going to look similar to the RR engines on British Airways 747-400s, 757-200s, and 767-300s?

User currently offlineTSV From Australia, joined Nov 1999, 1641 posts, RR: 5
Reply 4, posted (14 years 7 months 4 days 21 hours ago) and read 774 times:

Hi TEDSKI :

Good question. I sort of just asked that question of Ravi.

Judging by the computer generated images on the Airbus website (have a look at the if you get the chance) the Trent 500 (thanks for the number I couldn't remember what number it was) looks bigger than the RB211-whatever/G/H/T/whatever on the aircraft you mention however it doesn't look as big as the Trent on the 777. I suppose another way of verifying this is to look at the respective thrusts of 40 000 lb (?), 55 000 lb(?), and 70 000 lb(?) or whatever are being quoted.

What would be good on this forum is if one of the design type guys (or gals - mustn't be sexist!) could explain the sizing of engines for an aircraft based on the number of engines. I don't know what I'm talking about in terms of accurate numbers but a good example would be something like the A330 and A340 where the A330 has two x lbs thrust engines while the A340 has four y lbs thrust engines. And then explain that twin engined aircraft are designed for one engine out and four engined aircraft are also designed for one engine out or whatever. Obviously it may not be this simple but some sort of explanation would be helpful.

This might illustrate the A340-200/300 's situation a little better.

Any takers?



"I told you I was ill ..." Spike Milligan
User currently offlineR347216 From Canada, joined Dec 1999, 159 posts, RR: 0
Reply 5, posted (14 years 7 months 4 days 21 hours ago) and read 769 times:

Will somebody please explain to me. Underpowered. Underperformance. Now, do I understand that there are airlines paying multi millions for airplanes that have underpowered engines? Underpowered to me means that the engine is not man enought to lift that airplane fully loaded off the ground and keep it up there. So do I have to believe that that there are pilots, very skilled and knowledgeable at what they do, are sitting in the cockpit knowing that they are driving a plane with engines that can't cut it. I doubt very much if a pilot who is usually a person who very carefully thinks things out, would even attempt to take that plane up and I like to think that they are more knowledgable than us forum quarterbacks. If this is the case of underpowered engines, I have to wonder why these Airbuses with underpowered engines are not falling out of the sky on a daily basis. Anybody going to explain this to me? I have a thirst for knowledge when it comes from somebody who knows the real facts. Regards to all Peter

User currently offlineTurbulence From Spain, joined Nov 1999, 963 posts, RR: 20
Reply 6, posted (14 years 7 months 4 days 20 hours ago) and read 759 times:

Look everybody, folks!!!

I do not know very much about these things. I quiet understand what 200 HP mean for a car, but, unless I love them, I do not reach too much how to catch the idea of 50,000 lbs thrust for a plane or for its engine. Nevertheless, I mainly agree with R347216 (by the way: What the h*ll does it mean, Peter?) that a big company would never buy such "underpowered" planes, and still more, that a big company would never sell them.
First of all, what can "underpowered" mean when a four-engine a/c has been tested in fully loaded take off with only two engines? Where is the difference between cruising at mach.82 and mach.83, when the oldest beoing 737 (the -200) is much faster than the newer -400? Nowadays, the main goal is not to cruise one point faster, but burning 30% less at same speed... And the 330s and the 340s are profitable to fly even with cargo only, without passengers... It is true that there are more powerful engines being issued for 340s as option, but it DOES NOT MEAN in any way that the present ones are mistaken...

Who else does share my point of view?

Many greetings and best turbulences for everybody!!


User currently offlineMD-90 From United States of America, joined Jan 2000, 8507 posts, RR: 12
Reply 7, posted (14 years 7 months 4 days 16 hours ago) and read 749 times:

Ain't none of you know what UNDERPOWERED is until you fly a 160 hp Piper Cherokee with 4 people and aboult half fuel on a 95 degree day in humid Mississippi! The most climb I could get out of that poor plane was around 300 fpm! That being pretty anemic, I struggled up to 8,000 feet as soon as possible so I'd be able to find someplace within gliding range in case the engine quit.

Having said that, I say that since the A340 has 4 engines and the 777 only 2, they had to do something to make it competitive. Therefore they had to keep the engines small so the fuel flows would be nice and low. As far as I know, the FAA and JAA only require testing with 1 engine out, so the 777 would have to be much more powerful in order to lose 1/2 its thrust yet takeoff at max gross on a 100 degree day at a 5000 ft. density altitude. Seeing as how the A340 would only lose 1/4 of its thrust, they went for small engines for fueling efficiency.

'Nuff said.

Total Thrust:
777 - 150,000? to 230,000? lbs.
MD-11 - 180,000 to 186,000 lbs.
A340 - 128,000? to 146,000 lbs. (for the CFM powered ones)


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