flipdewaf
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Re: Why is the A343 "underpowered"?

Thu Nov 16, 2017 5:04 pm

Andre3K wrote:
We are literally talking about the acceleration aspect here.
Well you are...
Andre3K wrote:
Ok let me make this simple.

No matter what you do or say, if a A340-300 and A340-600 were lined up on tandem runways, in perfect conditions for engine performance. And they are both at max takeoff weight, the -600 will beat the -300 to 100 knots without a doubt.
And there was me thinking that the job of the jet was to get me on my holidays safely and in a timely fashion, thank god you reminded me its about drag racing.

Andre3K wrote:
THERE IS NO SUBSTITUTE FOR THRUST.
There is, its called reducing drag but you apparently don't want to listen to that

Andre3K wrote:
Or are we going to start making fighter jet's with less thrust now because of wing efficiency?
They do both, that's why a typhoon has a different looking wing to a lightning.

speedbird52 wrote:
Has society reached a point where people feel offended over hearing that an airplane doesn't have enough power?
No, but it appears that some arts of society don't like it when the facts don't agree with their opinions.

Andre3K wrote:
Again that’s been sidestepping the point. I’m sure the majority here I know that flex takeoffs are the norm. But there is no getting around the fact that the A340-300 has less power for its weight than either of the later models. Anyone who would argue against that is just blinded by stupidity(not saying you, just a general statement)
I don't think anybody has argued with that point. The A346 has higher T/W than an A343. Your assumption that that constitutes being underpowered however is what is being argued

Andre3K wrote:
What i do know is that the thrust to weight ratio is much lower for the -200/300 models over the -500/600.

Are you ever going to speak on that or just keep bringing up things even you have no numbers for?
People have spoken on it to say that there is more to being underpowered than a simple ratio of thrust to weight, that fact that you don't want to listen is no ones fault or problem but yours.

Andre3K wrote:
Do me a favor, answer this one question. If you put a giant scale behind a A340-300 and an A340-600 and connected them via some cable at an appropriate hard point, which one would pull harder?
The A346, it has more thrust, it also has more thrust than a 77X, is that underpowered?

Andre3K wrote:
I am only talking about the difference in T/W of the -200/300 vs the -500/600.
You want to compare two different aircraft together which fit your argument of being under/overpowered but ignore other aircraft, is this correct?

Andre3K wrote:
The increase in thrust is much higher than the increase in weight.
Agreed
Andre3K wrote:
Let’s talk about that. Can we do that?
Many people have talked about it and explained why it is the case and why it does not constitute being underpowered. People have talked and you haven't listened.

Fred
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SheikhDjibouti
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Re: Why is the A343 "underpowered"?

Thu Nov 16, 2017 5:29 pm

↑↑↑ (what flipdewaf said) ↑↑↑

:checkmark: +1

flipdewaf - I was composing my own response, but you took the words right out of my mouth. :D
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Balerit
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Re: Why is the A343 "underpowered"?

Thu Nov 16, 2017 8:27 pm

Just watched a lovely video on a Swiss Air A340 that had an oil o/h on number 3 eng. They had to shut it down and dump fuel and return to Zurich. The pilots reaction: "Ok, we'll shut the engine down and I'll have some chocolate."
Licensed Aircraft Maintenance Engineer (retired).
 
Andre3K
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Re: Why is the A343 "underpowered"?

Thu Nov 16, 2017 9:34 pm

SheikhDjibouti wrote:
Andre3K wrote:
Chaostheory wrote:

Someone posted an AF A340 takeoff clip from Juliana a few months ago. It shows the A340 can move when she needs to.


You mean when it's nowhere near MTOW like all the other aircraft that takeoff out of there?

I haven't watched the video, and neither do I know the exact circumstances. But apparently you do.
Why was this A340 nowhere near MTOW? Was it on a positioning flight? Had all the passengers missed their connections?

And why do "all the other aircraft" take off at or near MTOW?
SXM -AMS is only 3747nm, and SXM-CDG even less. Are those planes at MTOW?
What about the US flights? Isn't the US even closer?



You obviously misunderstood me. I never said all the other aircraft were at MTOW. I was saying the A340 was no different in that it takes off from SMX well below MTOW. Hence the “like all the other aircraft” vs “unlike all the other aircraft”.
 
speedbird52
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Re: Why is the A343 "underpowered"?

Thu Nov 16, 2017 10:54 pm

People over here I acting like they have something emotionally invested in the A340 being either properly powered or underpowered.
"I have control" Three Words That Could Have Saved Lives.
 
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Ty134A
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Re: Why is the A343 "underpowered"?

Fri Nov 17, 2017 12:44 am

there is really only one approach to that topic of the a340, and that is to any topic actually.

you should be in the know before forming an opinion. patriotism, emotions or feelings won't get a plane airborne. i very much like these kind of threads, since it really shows who has industry insight, and who really doesn't know anything, but what he sees from his window seat.

for starters be smart and ask yourself if plane building companies didn't think of what you thought of. ask yourself, it the money involved in this business might lead to pretty smart people thinking of what they are doing... and so on.

now i know there are lot's of planes considered commercial failures, especially within this community here. but after taking a closer look, i never have seen any fundamentally wrong decisions in this business (plane building, not exploiting). some examples: was/is/will the ARJ21 be a complete fail? there is a thread going on here flaming the plane... well, i was aboard one of those, and while the plane might not exactly be the most favourable product on the market, it makes perfectly sense to build it the way it is - beginning with the Y-10 - leading up to the C919.

the a340 and it's performance makes by every means perfect sense to those that understand the business. and even the a340-500 and -600 are legitimate planes. even Mercure was to become the a320, so again, not a big deal. there are examples though of misinterpretation of market needs thus the performance of the plane was not "good". take convair or lockheed, or in the end the MD-90/95 srs. those did underperform. the a340 and it's engines definitely did not. or is there a case in which any one flight could not be performed by the a340-300 since its performance did not meet it's specs?

btw talking about engine power:
http://www.youtube.com/watch?v=_fdhr3yaQ2Q
flown on: TU3,TU5,T20,IL8,IL6,ILW,IL9,I14,YK4,YK2,AN2,AN4,A26,A28,A38,A40,A81,SU9,L4T,L11,D1C,M11,M80,M87,
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Andre3K
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Re: Why is the A343 "underpowered"?

Fri Nov 17, 2017 2:21 am

flipdewaf wrote:
Way to much to re-quote


Look at the title of the thread. Unless it has changed it says "Why is the A343 "underpowered"?

It doesn't say "Why is the A343 "under performing"? I guess you must cherry pick what you want to speak on because you missed when I clearly said being low on thrust does not prevent the A340-200/300 from achieving the design mission, and doing it efficiently. And like I said earlier, why compare a quad to a twin? All people here love to do is quote things like "well if you factor in engine out performance bla bla bla 3 engines bla bla bla 1 engine". Ok how many pilots takeoff expecting to lose an engine EVERY TIME? You stay ready but if you actually think your going to lose an engine on every takeoff, maybe you shouldn't be flying.

And reducing drag is not a substitute for thrust. Drag cannot be eliminated, thrust can be increased to the point of ridiculousness.

Power is the rate of doing work. The A340-200/300 does less of it. It's under powered, it didn't sell well. Both true, not sure why that hurts you so bad? But I await more comical responses from you.
 
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Starlionblue
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Re: Why is the A343 "underpowered"?

Fri Nov 17, 2017 2:32 am

Andre3K wrote:
flipdewaf wrote:
Way to much to re-quote


Look at the title of the thread. Unless it has changed it says "Why is the A343 "underpowered"?

It doesn't say "Why is the A343 "under performing"? I guess you must cherry pick what you want to speak on because you missed when I clearly said being low on thrust does not prevent the A340-200/300 from achieving the design mission, and doing it efficiently. And like I said earlier, why compare a quad to a twin? All people here love to do is quote things like "well if you factor in engine out performance bla bla bla 3 engines bla bla bla 1 engine". Ok how many pilots takeoff expecting to lose an engine EVERY TIME? You stay ready but if you actually think your going to lose an engine on every takeoff, maybe you shouldn't be flying.

And reducing drag is not a substitute for thrust. Drag cannot be eliminated, thrust can be increased to the point of ridiculousness.

Power is the rate of doing work. The A340-200/300 does less of it. It's under powered, it didn't sell well. Both true, not sure why that hurts you so bad? But I await more comical responses from you.


We don't expect to lose an engine on every take-off, but we do plan for the possibility on every take-off. That's how airliner take-off performance calculation works.

Reducing drag is very much a substitute for adding thrust. Thrust and drag are (mostly) opposing forces in flight. If you can reduce your drag in all phases by 2%, for example by adding winglets, you need less thrust for the same payload. You can't eliminate drag but there are many ways to decrease it. And certainly you can add thrust but that may mean adding weight (heavier engines) and/or frontal area (larger engines). Trade-offs all over the place.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
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zeke
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Re: Why is the A343 "underpowered"?

Fri Nov 17, 2017 7:02 am

Very well put IMHO
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WIederling
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Re: Why is the A343 "underpowered"?

Fri Nov 17, 2017 9:40 am

Andre3K wrote:
Ok how many pilots takeoff expecting to lose an engine EVERY TIME? You stay ready but if you actually think your going to lose an engine on every takeoff, maybe you shouldn't be flying.


You have to expect loosing an engine every time. That is procedure.
All your planning revolves around getting air born without further mishap on one engine out ( after V1 ).

Before V1 you go the RTO route for a stop with glowing brakes at the outer threshold.

You do know thought hat the "1 engine out" _probability_ is reasonably low.

IMU your are caught up in imprecise semantics.

"underpowered" as the word "under" indicates is below needs and will lead to underperformance.
Murphy is an optimist
 
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77west
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Re: Why is the A343 "underpowered"?

Fri Nov 17, 2017 9:43 am

This is such a tedious topic. Does the A340-200/300 have a lower than average T/W ratio - yes. Does the B757 have a higher than average T/W ratio - yes. Does this mean either is bad or not optimised - no. Would I trust an A340 to get me to where I am going - absolutely. It is a vehicle. They wont all have exactly the same performance. They operate in different regimes. The manufacturers would not have had them certified if they were not capable. I would happily take off from JNB on a hot summer afternoon in and A340-300 knowing if we lost an engine we would still have time to finish our champagne before landing. I would be just as comfortable on a 77W. It is calculated and planned for.

People here go on like it is a drag race between two Kias in a cheap supermarket parking lot.

Sigh...
77West - AW109S - BE90 - JS31 - B1900 - Q300 - ATR72 - DC9-30 - MD80 - B733 - A320 - B738 - A300-B4 - B773 - B77W
 
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Faro
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Re: Why is the A343 "underpowered"?

Fri Nov 17, 2017 10:25 am

Chaostheory wrote:
Someone posted an AF A340 takeoff clip from Juliana a few months ago. It shows the A340 can move when she needs to.



Any jet airliner at light weight will perform like a rocket...a light A340 on a go-around is likely capable of climb gradients of 15°-20° degrees if not more...



speedbird52 wrote:
Has society reached a point where people feel offended over hearing that an airplane doesn't have enough power?



It is not society as a whole but a very peculiar subset thereof...the a.nut aviation enthusiast...or at least the amateur aviation enthusiast for whom brute takeoff performance is 90% of what aviation is all about...it's the sexiness factor, which has very little to do with safety or efficiency...


Faro
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Andre3K
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Re: Why is the A343 "underpowered"?

Fri Nov 17, 2017 5:12 pm

Faro wrote:
Chaostheory wrote:
Someone posted an AF A340 takeoff clip from Juliana a few months ago. It shows the A340 can move when she needs to.



Any jet airliner at light weight will perform like a rocket...a light A340 on a go-around is likely capable of climb gradients of 15°-20° degrees if not more...



speedbird52 wrote:
Has society reached a point where people feel offended over hearing that an airplane doesn't have enough power?



It is not society as a whole but a very peculiar subset thereof...the a.nut aviation enthusiast...or at least the amateur aviation enthusiast for whom brute takeoff performance is 90% of what aviation is all about...it's the sexiness factor, which has very little to do with safety or efficiency...


Faro


Don't get me wrong. It's not all about brute power. It's just a point. By today's standards the A340-200/300 is a little shy on the T/W ratio. Some people are trying to pretend that is not a true statement.

We are are also aware that there is more to takeoff performance(once the aircraft has started to rotate) than brute force. For example a fully loaded DC-10-30ER has a pretty good thrust to weight ratio but the wing is nowhere near as efficient as the A340-200/300. A such, the first time I flew on one during my first deployment in the USAF it was VERY noticeable how slowly it climbed out (Even with the higher pitch angle that MD aircraft seem to have in general). Of course being all coach, no empty seats, and 100lb of bags per person probably didn't help.

And yes being an aviation enthusiast is all about learning, questioning and discussion. Anyone who has a problem with that probably needs to sit down for a while( Not directed at you).
 
WIederling
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Re: Why is the A343 "underpowered"?

Fri Nov 17, 2017 6:38 pm

Andre3K wrote:
By today's standards the A340-200/300 is a little shy on the T/W ratio.


You are still missing the point. The A340 / A330 airframe layout is such that it needs less thrust.

The A330 with the same fuselage and wing is relatively underpowerd ( by your metric ) too.
77W has T/W of .3 An early 230T A330 has .27 and todays 242t version as a T/W of .255
( nominal thrust never changed much.)

now the A340-5/600 has for more MTOW the same High Lift arrangement carried over from the family wing
higher wing loading and worse L/D. ergo it needs a higher T/W ratio.

Thrust, High lift design, wing area, L/D with High Lift extended, MTOW are inseparably interdependent.
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zeke
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Re: Why is the A343 "underpowered"?

Fri Nov 17, 2017 6:53 pm

An A343 one engine out has 102 klb of thrust (3x34klb) for 275 tonnes MTOW, the 77X has 105 klb one engine out for 351.5 tonnes.
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WIederling
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Re: Why is the A343 "underpowered"?

Fri Nov 17, 2017 7:04 pm

zeke wrote:
An A343 one engine out has 102 klb of thrust (3x34klb) for 275 tonnes MTOW, the 77X has 105 klb one engine out for 351.5 tonnes.


minimum climb for the twin is lower than for the quad, isn't it?
Murphy is an optimist
 
Andre3K
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Re: Why is the A343 "underpowered"?

Fri Nov 17, 2017 7:08 pm

WIederling wrote:
Andre3K wrote:
By today's standards the A340-200/300 is a little shy on the T/W ratio.


You are still missing the point. The A340 / A330 airframe layout is such that it needs less thrust.

The A330 with the same fuselage and wing is relatively underpowerd ( by your metric ) too.
77W has T/W of .3 An early 230T A330 has .27 and todays 242t version as a T/W of .255
( nominal thrust never changed much.)

now the A340-5/600 has for more MTOW the same High Lift arrangement carried over from the family wing
higher wing loading and worse L/D. ergo it needs a higher T/W ratio.

Thrust, High lift design, wing area, L/D with High Lift extended, MTOW are inseparably interdependent.


You clearly will never say the words so I'm done with you. The A340 didn't sell well, so it doesn't really matter that it was under powered (or maybe that didn't help).

Hell the A330 is lower on the T/W scale as well but it doesn't perform that way.

BTW are you admitting that the 500/600 were sub-optimal upgrades? Oh my that's bad, Airbus wasn't perfect at something. :|
 
vikkyvik
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Re: Why is the A343 "underpowered"?

Fri Nov 17, 2017 10:19 pm

Andre3K wrote:
The A340 didn't sell well, so it doesn't really matter that it was under powered (or maybe that didn't help).


If by "underpowered" you mean "has a smaller thrust-to-weight ratio than some other modern airplanes" then the answer is yes.

But since that's a pointless definition of "underpowered", and is just one variable in a large scheme of things, who cares?

A better definition of "underpowered" is "does not possess the required power to complete its missions in a cost-effective and efficient manner". And I think that has been addressed ad nauseum in this thread.

Andre3K wrote:
By today's standards the A340-200/300 is a little shy on the T/W ratio. Some people are trying to pretend that is not a true statement.


No they're not. They're simply asserting that that statement doesn't matter on its own.
I'm watching Jeopardy. The category is worst Madonna songs. "This one from 1987 is terrible".
 
WIederling
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Re: Why is the A343 "underpowered"?

Fri Nov 17, 2017 10:25 pm

Andre3K wrote:
BTW are you admitting that the 500/600 were sub-optimal upgrades? Oh my that's bad, Airbus wasn't perfect at something. :|


Beyond grating on some nerves elsewhere I didn*t do anything bad. So why should I admit anything. :-()

The A340NG pushed Boeing to the 77W and extending ETOPS further.
Airbus definitely didn't get a grip on weights initially.
It cost about half of what Boeing spent on the 748.

Before you get zany on performance elsewhere you should work on your own "performance" :-)
You still lack the holistic approach required from an engineer.
Murphy is an optimist
 
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SheikhDjibouti
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Re: Why is the A343 "underpowered"?

Sat Nov 18, 2017 12:05 am

Finally, we see Andre3K's true colours.
Andre3K wrote:
You clearly will never say the words so I'm done with you. The A340 didn't sell well, so it doesn't really matter that it was under powered

And all this time we thought this was a rational debate about power-to-weight ratio.
How stupid of us.
It turns out we had a TROLL in our midst; using a bogus argument to point out the A340's poor sales record.

I might as well have conceded the A340 was under-powered, and then added "but the Boeing 777 smells like a farmyard". It's just as off-topic. And just as incorrect.

Best of all, after 17 posts from him on this subject, it turns out that it "doesn't really matter that the A340 was under-powered" :banghead:
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Faro
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Re: Why is the A343 "underpowered"?

Sat Nov 18, 2017 10:03 am

zeke wrote:
Your thrust to weight ratio “law” isn’t actually true.



:checkmark:

You need thrust-to-weight + wing loading + L/D ratio to arrive at an appropriate determination...


Faro
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BawliBooch
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Re: Why is the A343 "underpowered"?

Mon Nov 20, 2017 3:41 am

LY777 wrote:
Hi guys,
I have always why the A343 is "underpowered".

It isnt. That is just a bedtime story Boeing fan-girls tell themselves. An A340 has sufficient power to operate safely.


LY777 wrote:
I flew it yesterday and the take off roll was so long (with so much vibration)! And the climb was so slow!

Was flex being used for your takeoff?
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Starlionblue
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Re: Why is the A343 "underpowered"?

Mon Nov 20, 2017 4:41 am

BawliBooch wrote:
LY777 wrote:
Hi guys,
I have always why the A343 is "underpowered".

It isnt. That is just a bedtime story Boeing fan-girls tell themselves. An A340 has sufficient power to operate safely.


LY777 wrote:
I flew it yesterday and the take off roll was so long (with so much vibration)! And the climb was so slow!

Was flex being used for your takeoff?


We can't know, but most likely both FLEX for takeoff and derate for climb.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
Andre3K
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Re: Why is the A343 "underpowered"?

Tue Nov 21, 2017 2:09 am

MTOW lb of aircraft per lb of thrust

Original 707-120: 4.75
(Stongest engine)707-320: 4.45

747-100(Weakest engine): 4.22
747-400ER(Strongest engine): 3.59
747-8i: 3.71

A340-300(Strongest engine): 4.48
A340-600(Strongest engine): 3.39(This thing has some POWER!!!!)
A380-800(Strongest engine): 3.95

Looking at it this way you can't deny that it's down near the bottom. But at the same time, the -600 A340 is a beast.
 
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AirlineCritic
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Re: Why is the A343 "underpowered"?

Tue Nov 21, 2017 6:52 am

This is a silly thread.

Judging airplane performance from passenger experience (long roll etc) is like saying a car is underpowered because it drives slowly.

And of course, all 4-engine aircraft have less power reserve than 2-engine aircraft, because math. And even among the 4-engine aircraft, the 340 probably had less reserve than many others.

That being said, I don't understand how "high-powered" or "underpowered" or anything of the sort is an adjective people assign feelings or desires to. I'll propose a word game. Every time you were about to write "underpowered", write "fuel-efficient" or "optimal" instead. And every time you were about to write "high-powered", write "the SUV version" or "rolling coal version of an airplane" :-) Or "aircraft with too much engine on it" :-)

And yet, of course,. there'd be situations where airplanes truly are underpowered, in that they impact missions or safety. It would be an interesting exercise to figure out what the definition of "underpowered" is.

Is it:

* Can't get out of major hot-and-high airports (but: the 340 is one of the best aircraft for this purpose).

* Can't climb after engine out or other problems (but: rules prohibit such aircraft from existing)

* Can't perform an impressive airshow manoeuvre (but: almost all aircraft can, just fly them tanks empty and no load, see F-35)

* Comfortably wins any dogfight situation with F-16

* Impressive on a subjective basis to an a.netter or spotter

* ... something else, what?
 
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Faro
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Re: Why is the A343 "underpowered"?

Tue Nov 21, 2017 10:31 am

Andre3K wrote:
MTOW lb of aircraft per lb of thrust

Original 707-120: 4.75
(Stongest engine)707-320: 4.45

747-100(Weakest engine): 4.22
747-400ER(Strongest engine): 3.59
747-8i: 3.71

A340-300(Strongest engine): 4.48
A340-600(Strongest engine): 3.39(This thing has some POWER!!!!)
A380-800(Strongest engine): 3.95

Looking at it this way you can't deny that it's down near the bottom. But at the same time, the -600 A340 is a beast.



One of the design goals of the original 727-100 was the opening up of smaller airports to jet service in the mid-1960's, airports that could not accomodate the earlier 707 and DC-8 turbojet versions, and airports with performance limitations like Denver. Consequently the 727-100 had spectacular airfield performance, anyone amongst the A.net 1960's veterans can tell you that it had a far far higher level of performance than the A340-600. And this despite having about 3.81 lbs of MTOW per lb of thrust.

And why? Because it only had a wing loading of around 94 lbs/ft^2 at MTOW compared to the A340-600's loading of 178 lbs/ft^2 at MTOW. And it also a very effective high-lift system for slow-speed flight incorporating -amongst others- triple-slotted flaps against the A340-600's single-slotted layout.

It had much lower wing loading and a more effective high-lift system designed for shorter runway lengths.

Thrust-to-weight is one consideration. It is far from being the only or the most important one...


Faro
The chalice not my son
 
LH707330
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Re: Why is the A343 "underpowered"?

Tue Nov 21, 2017 5:22 pm

AirlineCritic wrote:
This is a silly thread.

That being said, I don't understand how "high-powered" or "underpowered" or anything of the sort is an adjective people assign feelings or desires to. I'll propose a word game. Every time you were about to write "underpowered", write "fuel-efficient" or "optimal" instead. And every time you were about to write "high-powered", write "the SUV version" or "rolling coal version of an airplane" :-) Or "aircraft with too much engine on it" :-)

Agreed. A good design means having the smallest reasonable engines on there to keep weight down and also to keep higher loads, and consequently higher pressure ratios, on the engine. There was a good thread here a while back where that was discussed specific to the 343 design and how they did a damn good job of accomplishing that.

Regarding the T/W comparisons to those other designs, the 343 can get away with less thrust because it's got a better L/D, especially against the 747.

To bring this full circle, the best answer to the OP's question is "The A340-300 has lower engine thrust than other designs because the designers were laser-focused on making it as efficient as possible."
 
tommy1808
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Re: Why is the A343 "underpowered"?

Fri Nov 24, 2017 3:42 pm

LY777 wrote:
Hi guys,
I have always why the A343 is "underpowered".
I flew it yesterday and the take off roll was so long (with so much vibration)! And the climb was so slow!


That is just a myth. When airlines flying both, A333 and A343, like LH, are in a pickle regarding take off performance, they use the A343.

The A343 has a lower trust to weight ratio, but it would only be "underpowered" if that effects performance. Which apparently it doesn´t, Airlines would not have used the A340 as they did.

best regards
Thomas
Times are changing: 70 years ago the USA went to war to defeat the Nazis, now they elect them to run their country.
 
bananaboy
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Re: Why is the A343 "underpowered"?

Sat Nov 25, 2017 9:42 am

Fascinating thread (for many reasons!). Did I read from a poster on this site that climb performance for the A340-200/300 was better than the 747-400? Anyone able to confirm?

If so, how has the aircraft developed this reputation, if it even exists outside of this site?

On a seperate note, flew MNL-LHR in A343 with PR. Felt a little like we were having a scenic flight over the city on takeoff!

Mark
All my life, I've been kissing, your top lip 'cause your bottom one's missing
 
Clipper136
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Re: Why is the A343 "underpowered"?

Sun Nov 26, 2017 3:59 am

This entire thread is a sad reflection of today's society as a whole. People are so busy arguing their opinion that facts become irrelevant. A flawed argument looked at and supported thru myopic vision will always remained flawed because new or different information is not acceptable. This site is filled with may talented and experienced aviation professionals. If you pose a question (argument) and get feedback from experts (people who operate, build and maintain these wonderful machines everyday), one would do well to stop being defensive for a second and really listen to what is being said. You may lean a thing or two. I know I lean something new here everyday.
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DocLightning
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Re: Why is the A343 "underpowered"?

Sun Nov 26, 2017 11:30 pm

I will point out that I have never heard of an airline CEO publicly complaining that the reason his or her airline chose the 772 over the A343 is because of the A343's asthmatic takeoff and climb performance. Airbus went through a lot of scenarios (and also had to deal with the fact that the RR Superfan never materialized) to determine what kind of drag profile and thrust profile would provide the most economic performance. The result is that the A343 does not provide a "gee-whiz" takeoff performance that slams you back into your seat and rockets you off the ground like a lightly-loaded 757 at max thrust. I remember once in the late 1990s reading a document from Airbus defending and acknowledging the relatively unimpressive-seeming performance of the A340, but I can't find it anywhere online now. In that document, Airbus argued that the 747 was overpowered because it had an obsolete airfoil and high-lift system that created more drag. I really wish I could find that document now.

The 777 outsold the A343 because the 777 was able to do a similar job with more cargo space and a wider (more flexible) fuselage on two fewer engines. When both the A340 platform and the 777 platform were stretched into the A345/6 and the 77L/W, the new A340s had improved takeoff performance because some airlines had complained that there were some isolated cases in which the A343's wheezy takeoff performance was presenting operational challenges due to short runway lengths at certain stations. The A346 offered more payload over more range and yet, *still* the 777 vastly outsold these newer A340s. Again, when presented with two engines vs. four, airlines opt for two. In particular, the A346 has a higher fuel delta vs the 77W than the A343 vs. the 772.(1)

Also, as others have pointed out, aircraft takeoff and climb performance is defined by the engine-out characteristics of the aircraft, not its performance when all engines are running. That actually gives the A340 better characteristics than most twins, especially at high elevations, but it still uses a lot of runway (about 1,000 feet more than a 772) owing to a sluggish acceleration profile.

(1)http://www.aircraft-commerce.com/sample_articles/sample_articles/flight_operations_sample.pdf
-Doc Lightning-

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LH707330
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Re: Why is the A343 "underpowered"?

Tue Nov 28, 2017 5:21 am

DocLightning wrote:
I remember once in the late 1990s reading a document from Airbus defending and acknowledging the relatively unimpressive-seeming performance of the A340, but I can't find it anywhere online now. In that document, Airbus argued that the 747 was overpowered because it had an obsolete airfoil and high-lift system that created more drag. I really wish I could find that document now.

The good news is I remember the threads where that came up and was able to find it, but the bad news is that the image is gone.
viewtopic.php?f=5&t=776457
viewtopic.php?f=3&t=599359 (in this one, page 2)

Zeke, could you repost that by any chance?

The rest of those threads basically regurgitate many of the same points brought up here, I'd encourage OP to check them out.
 
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seahawk
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Re: Why is the A343 "underpowered"?

Tue Nov 28, 2017 7:31 am

With all engines operating the twin always uses less runway, simply because it has to. All engines running is never the limiting factor, one engine out is and in that case a twin takes longer from V1 to V2 than a quad, so with all engines running it needs to accelerate faster to create the needed safety margin for an engine failure above V1 but below V2.
 
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zeke
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Re: Why is the A343 "underpowered"?

Tue Nov 28, 2017 9:45 am

LH707330 wrote:
[



Zeke, could you repost that by any chance?


I got it on my photo bucket but they want a silly amount of money to share photos online now.
Human rights lawyers are "ambulance chasers of the very worst kind.'" - Sky News
 
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zeke
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Re: Why is the A343 "underpowered"?

Tue Nov 28, 2017 9:48 am

seahawk wrote:
With all engines operating the twin always uses less runway, simply because it has to. All engines running is never the limiting factor, one engine out is and in that case a twin takes longer from V1 to V2 than a quad, so with all engines running it needs to accelerate faster to create the needed safety margin for an engine failure above V1 but below V2.


Simply is not true, some twins at maximum weight using maximum trust will use less runway than an A340 at max weight and max thrust. Some twinsuse more, they tend to be twins with longer fuselages that are geometry limited on takeoff.
Human rights lawyers are "ambulance chasers of the very worst kind.'" - Sky News
 
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seahawk
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Re: Why is the A343 "underpowered"?

Tue Nov 28, 2017 11:26 am

You just added another factor, apart from the number of engines.
 
LH707330
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Re: Why is the A343 "underpowered"?

Tue Nov 28, 2017 9:04 pm

zeke wrote:
LH707330 wrote:
[



Zeke, could you repost that by any chance?


I got it on my photo bucket but they want a silly amount of money to share photos online now.

Bummer, I remember that was a good read.
 
Flighty
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Re: Why is the A343 "underpowered"?

Wed Nov 29, 2017 3:48 am

Andre3K wrote:
WIederling wrote:
Andre3K wrote:
Last time I checked WING AREA and THRUST were not the same thing. We aren't talking about climb performance. We are literally talking about the acceleration aspect here. Stop trying to skirt around the issue.


If I skirt around anything at all it is your limited grasp of the physics involved. :-)

Question of V1/V2 values.

More wing and better high lift ( no thrust gate forex ) will need less thrust to lift off.
A large well designed wing will have higher L/D which again needs less thrust.

A 777 has all the omphf you seem to expect but can't bring it to bear
as the tire speed limit is reached before all of the runway available is used.

to wit the A343 has all the thrust it needs :-)
The A345/6 have worse L/D and thus need more thrust per ton MTOW.
It all fits together and is definitely not "independent".


Do not confuse my lack of A.net dissertation's for lack of understanding. I was shoving these posts out in the few breaks I have at work.

Why are you bringing up the 777? I'm not comparing a quad to a twin, that's ridiculous.

Do me a favor, answer this one question. If you put a giant scale behind a A340-300 and an A340-600 and connected them via some cable at an appropriate hard point, which one would pull harder?

Let's take an example where none of you can start shoving in a million other variables, one that is closer to home for me.

The C-5B had 43,000lb of thrust for each engine, the C-5M has about 53,000lb of thrust per engine. The performance between the two is night and day. For a plane as heavy as the 747 it was under powered, can we all agree? Of course it could still fly mission's, but not like it does as the C-5M. The original engines were almost as weak as the C-17 engines which is sad for a plane that weighs so much more. Yes the C-5 wing is a high lift wing but it's also designed in the 50/60's. Lockheed admitted by proxy that the C-5 was under powered 2 times now. The first was the step up from 41,000lb thrust to 43,000lb thrust and then of course the -M mod.

That is a VERY similar situation they A340 had going on. The difference is, in the military they just add more power, in the civilian world they usually try change other aspects in the process as well.


Not a pilot but I do have firsthand knowledge about airline finance and scheduling. Can you offer an example why an airline would CARE about the A343's lack of power? The feeling of power or the gratification of a pilot does not count. What mission did the A343 fail to do?

HKG-JFK, pretty much, are we done here? The A330/A340 platform has a slower cruise than competing jets, making it a sub optimal >12 hour platform anyhow. What's the actual mission the A343 failed to do? Was it weight limited frequently?
 
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Balerit
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Re: Why is the A343 "underpowered"?

Wed Nov 29, 2017 4:59 am

This thread should be changed to: "Why does the A340 appear to climb slower than a 777?"
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Andre3K
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Re: Why is the A343 "underpowered"?

Wed Nov 29, 2017 7:17 am

Balerit wrote:
This thread should be changed to: "Why does the A340 appear to climb slower than a 777?"



If the comparison was to the 777 that might be a good point. But that was never stressed, because EVERYONE HERE knows twins are overpowered by necessity.

The comparison between the -200/300 and the -500/600 was my main talking point, and so if the title should be changed it should be:

"Why did Airbus increase the thrust to weight ratio so drastically with the heavier varients?"
 
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zeke
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Re: Why is the A343 "underpowered"?

Wed Nov 29, 2017 11:04 am

Because of the other things your fake thrust to weight “law” does not cover.

The reasons your “law” is fake and your contribution to this thread has been eloquently explained above by Faro

“You need thrust-to-weight + wing loading + L/D ratio to arrive at an appropriate determination...”
Human rights lawyers are "ambulance chasers of the very worst kind.'" - Sky News
 
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Balerit
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Re: Why is the A343 "underpowered"?

Wed Nov 29, 2017 12:01 pm

Andre3K wrote:
Balerit wrote:
This thread should be changed to: "Why does the A340 appear to climb slower than a 777?"



If the comparison was to the 777 that might be a good point. But that was never stressed, because EVERYONE HERE knows twins are overpowered by necessity.

The comparison between the -200/300 and the -500/600 was my main talking point, and so if the title should be changed it should be:

"Why did Airbus increase the thrust to weight ratio so drastically with the heavier varients?"


Ok, now we're getting somewhere. The simple answer is that the envisaged engine for the first A340, the IAE V2500 SuperFan, never materialized and Airbus was forced to redesign the plane around the CFM 56-5c - which had 3000 lbs less thrust.

This was achieved by increasing the wing size to have the same range with the less efficient engine. Also later on there was a better spread of engines available, allowing Airbus to design a new wing and stretch the fuselage. By the way, the B747 was also underpowered when it first entered the market.
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Andre3K
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Re: Why is the A343 "underpowered"?

Wed Nov 29, 2017 5:39 pm

Balerit wrote:
By the way, the B747 was also underpowered when it first entered the market.



Noted also, see my earlier table of thrust to weight ratio's.

Andre3K wrote:
MTOW lb of aircraft per lb of thrust

Original 707-120: 4.75
(Stongest engine)707-320: 4.45

747-100(Weakest engine): 4.22
747-400ER(Strongest engine): 3.59
747-8i: 3.71

A340-300(Strongest engine): 4.48
A340-600(Strongest engine): 3.39(This thing has some POWER!!!!)
A380-800(Strongest engine): 3.95

Looking at it this way you can't deny that it's down near the bottom. But at the same time, the -600 A340 is a beast.
 
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Balerit
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Re: Why is the A343 "underpowered"?

Wed Nov 29, 2017 5:56 pm

Our -200 Super B's could just make it out of JNB with max fuel, if the temps weren't too hot. They would virtually lift off with the dust billowing up from the end of the runway - was bad for the nerves if it was your aerie. The FEO's would tell me the amber warning lights would be lit on the EGT guages - nerve wracking for them too. If you parked at the end of the runway they would pass over you so low and you could see the turbines glowing red like stove plates.
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PHL9R
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Re: Why is the A343 "underpowered"?

Thu Nov 30, 2017 2:29 pm

An interesting article related to this topic...

Please see the link:
https://www.flightglobal.com/news/artic ... ar-443732/
 
KingOrGod
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Re: Why is the A343 "underpowered"?

Thu Nov 30, 2017 4:20 pm

Balerit wrote:
If you parked at the end of the runway they would pass over you so low and you could see the turbines glowing red like stove plates.


My favouritist memory from my early days at Smuts :)
 
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Balerit
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Re: Why is the A343 "underpowered"?

Thu Nov 30, 2017 6:01 pm

KingOrGod wrote:
Balerit wrote:
If you parked at the end of the runway they would pass over you so low and you could see the turbines glowing red like stove plates.


My favouritist memory from my early days at Smuts :)


:thumbsup: Those were the days, 162 tonnes of fuel, temp over 30 degrees in summer: "Hello ground, we're waiting for temp to drop 1 degree." Half an hour later, "Are we clear to start #1?" :o
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