boeing767-300
Posts: 622
Joined: Mon Sep 10, 2001 11:23 pm

A380 Underpowered?

Tue Nov 20, 2001 10:00 pm

After browsing through the Aircraft data section on this site it would appear that the A380 is somewhat underpowered. By dividing the MTOW by the total amount of thrust(lbs)
A380 800 MTOW 590 000kg with 4 x 72000lb Trent 900s equals 2.12 Kgs per lb thrust

Proposed 777 300X MTOW 341000kg with 2 x GE 115 000lb equals 1.47 kgs per lb of thrust

747 400 MTOW 396 895kg with 4 x GE CF680C2b1Fs at 61500 Lbs each equals 1.61

737 300 MTOW 56740kg with CFM56-3B2s at 22000lb equals 1.27 kgs per lb of thrust.

2.12 kgs per lb of thrust compared to a 744 of 1.61 is quite significant. about 25 to 30 percent less power to weight. I think it will be a little underpowered but then I'm sure more powerful engines will end up being fitted.

I guess the A380 will be about as exciting to watch taking off as an A340 300 which at MTOW 275000 and 4 x CFM5653C at 32550 lbs equals 2.11 kgs per lb of thrust almost the same as the A380.

What do others think
 
seagull
Posts: 334
Joined: Sat Jun 30, 2001 5:58 pm

RE: A380 Underpowered?

Tue Nov 20, 2001 10:49 pm

I think you need to convert your 747 thrust numbers to Kg or the weight to pounds and try your math again, you'll be in for a surprise!  Wink/being sarcastic

The twins can't be compared as the thrust requirement is based on the minimum climb after an engine failure, so losing half your thrust is the scenario as opposed to losing 25% of it. Twins have to be overpowered for that reason.
 
boeing767-300
Posts: 622
Joined: Mon Sep 10, 2001 11:23 pm

RE: A380 Underpowered?

Tue Nov 20, 2001 11:03 pm

The maths is approximate and should be right. all are MTOW in Kg divided by lbs of thrust (total) A380 800 590000kg and 288000lbs thrust vs 744 of MTOW 395000kg and 246000 lbs of thrust.

Or to put it in a simpler way an extra 195 tons for only an additional 32k, Seagull... you work it out!!

I agree with you twins need to have more power but as proposed the A380 is a long way short of the 744 on power to weight.
 
marc kobaissi
Posts: 107
Joined: Thu Mar 29, 2001 2:31 pm

RE: A380 Underpowered?

Tue Nov 20, 2001 11:39 pm


An Airbus? Underpowered? NEVER!!!
 
SQ325
Posts: 1274
Joined: Wed Jul 18, 2001 7:54 pm

RE: A380 Underpowered?

Wed Nov 21, 2001 12:26 am

@ Marc Kobaissi
Ever saw an A340-300 fully loaded taking off.
God bless there is the curvature of the earth.
That 's not a joke, I know a A340 Captain he told me that this Airbus climbs more slowly as a overloaded C152.

regards SQ
 
boeing767-300
Posts: 622
Joined: Mon Sep 10, 2001 11:23 pm

RE: A380 Underpowered?

Wed Nov 21, 2001 1:29 am

SQ365 You are not kidding and that was my point exactly. The A380 has about the same power to weight ratio and therefore will be just as exciting watching them take off.

I saw a 343 take off and I've seen nothing climb slower

 
seagull
Posts: 334
Joined: Sat Jun 30, 2001 5:58 pm

RE: A380 Underpowered?

Wed Nov 21, 2001 2:04 am

OK, I see you mixed pounds and kg in all cases, which is a bit odd. However, what you're also missing is the wing design and high lift devices which may change some of your assumptions on climb rate quite a bit!
 
cedarjet
Posts: 8103
Joined: Mon May 24, 1999 1:12 am

RE: A380 Underpowered?

Wed Nov 21, 2001 2:31 am

Seagull is right, an airliner flies on the wing, not on the engine thrust. This isn't the F104 Starfighter (aka Widowmaker) we're talking about. Compare square foot of wing surface to weight, 744 vs A380. Most important is the actual shape of the wing.

There are things about Boeing I prefer to Airbus, but few would dispute the fact that Airbus wings (designed by the British) are the best in the world.

By Underpowered what you really mean is Efficient.
fly Saha Air 707s daily from Tehran's downtown Mehrabad to Mashhad, Kish Island and Ahwaz
 
777236ER
Posts: 12213
Joined: Sat Aug 18, 2001 7:10 am

RE: Cedarjet

Wed Nov 21, 2001 3:06 am

I would counter that by claiming that the 777 wing is more advanced than the A340/A330 wing.
Your bone's got a little machine
 
WhiskeyNovembr
Posts: 96
Joined: Fri Nov 09, 2001 6:50 am

RE: A380 Underpowered?

Wed Nov 21, 2001 5:10 am

No, Cedarjet, what we mean by underpowered is, indeed, underpowered. As a passenger and as a pilot, I feel a heck of a lot more comfortable in an airplane that has enough excess thrust/climb ability to get out of sticky situations such as microbursts and wind shear. When you hit severe shear, firewall the throttles, and hang on for dear life while the stickshakers are going off, "efficiency" isn't going to save hundreds of lives. That's how I feel whether I'm in an A-340 or a C-152.
 
B1C17L1011
Posts: 96
Joined: Fri Jun 29, 2001 12:42 am

RE: Cedarjet

Wed Nov 21, 2001 5:13 am

The wings of the A330/A340 have many trailing devices on the rear of the flaps (I don't know what they are called) campared to about half as many on a 777. So I would say that the 777 wing is a cleaner and more efficient design.
 
SailorOrion
Posts: 1959
Joined: Tue Feb 06, 2001 5:56 pm

RE: A380 Underpowered?

Wed Nov 21, 2001 5:27 am

First of all, one cannot say that Wing X is more efficient than Wing Y when comparing wings of different airplanes. By the way, traditionally Boeing is doing lighter wings and Airbus is doing wings with less drag. It doesn't matter. Both are VERY efficient, otherwise we wouldnt fly for less then 1000 bucks around the globe. PERIOD.

Now, for the computations. I'll get the data off the web pages, and calculate thrust-to-weight ratio (TWR).

I will only compare 4-engined airplanes, because of the reason mentioned by Seagull.

STSL Thrust / MTOW:

A340-300:
605 kN / 2696 kN = 0,22

A340-600:
997 kN / 3579 kN = 0,28

A380-800:
1247 kN / 5494 kN = 0,23

B747-400:
1126 kN / 3894 kN = 0,29

Now Seagull here's one thing that you forgot. Apart from the very beginning of the flight (until you reach about 50ft) lift does NOT make an airplane climb. Thrust does. Which means, an aircraft with a higher TWR is ABLE to climb faster. Now please to consider these points:

1) Climb ratio does not have anything to do with safety.
2) Very few takeoffs do take place with maximum takeoff power.
3) Very few takeoffs are in fact performed at MTOW

Yes, an A380-800 will climb about as fast as a A340-300. But what does underpowered mean?

SailorOrion
 
CPH-R
Posts: 6064
Joined: Thu May 03, 2001 5:19 pm

RE: A380 Underpowered?

Wed Nov 21, 2001 8:00 am

What IS the importance in how fast it climbs? After all, it does give us spotters more time to look at it  Big thumbs up
 
AA737-823
Posts: 4955
Joined: Wed Mar 01, 2000 11:10 am

RE: A380 Underpowered?

Wed Nov 21, 2001 9:44 am

Okay folks, think about it a minute.

No matter how high-tech a wing is, that doesn't make the plane move faster. What gets a plane rolling down the runway is THRUST. I had no idea that the 380 would be as bad as the 340.

Additionally, it doesn't matter if the conversions are made or not, so long as the math is right you can compare numbers even if it's apples to MGTOW or peaches to LBS thrust.

So, I guess that y'alls point would be that the 380 has a much higher lift wing and therefore leaves the ground at, say, 120 knots??? Didn't think so.

Thrust also gets you out of the way in event of a go around procedure, not lift. During these situations, like takeoff, you need thrust to go up quickly, not lift alone. You're trying to ACCELERATE. The 340... doesn't do that well.

Additionally, you CAN compare twin to quad jet IN THIS CASE. That's because- whether they are overpowered or not- both types use full thrust on takeoff or go around situations. And we're talking about thrust to weight, not cruising power.

That's all I have to add, feel free to comment.

Randy
 
Notar520AC
Posts: 1517
Joined: Sat Jul 21, 2001 6:53 am

RE: A380 Underpowered?

Wed Nov 21, 2001 9:46 am

It was hard for me to believe that that "thing" could get into the air.
BMW - The Ultimate Driving Machine
 
Skystar
Posts: 1339
Joined: Thu Jan 13, 2000 3:58 pm

RE: A380 Underpowered?

Wed Nov 21, 2001 10:25 am

Very Simple Ratio

A340-313X (271ton)
weight/thrust
(271k*2.2046)/(4*34k)
= 4.39 units of weight for every unit of thrust
(275ton) = 4.29 weight units/thrust units (lb/lb). 4.46 without thrust bump.

Seems strange that the 275 ton has a better thrust weight ratio? CFM offers a 4% thrust bump for this 'super heavy' model.

A380-200
weight/thrust
(560k*2.2046)/(4*70k)
= 4.41

A380 wing loading (560k MTOW) 16.25
A340 wing loading (275k MTOW) 14.15

You're right, the A380 makes the A340 look spritely! The interesting thing is the A380 seems to be working on aerodynamic magic, with its very high wingloading. I don't understand how AI can claim to have so much magic with this plane - but I'm not the engineer.

With such low thrust ratios & high wing loadings, the A380 would have very low initial cruise altitudes. It must have a very special wing to be able to have significant performance.

Just remember one fact, you always have more power after losing one engine in a quad, than a twin - because quads have to make higher climb gradients without one engine, than twins.

Cheers,

Justin
 
DC10Tony
Posts: 991
Joined: Tue May 29, 2001 9:51 am

Boeing 767-300

Wed Nov 21, 2001 11:54 am

I think all Boeings are a little overpowered and Airbuses may be a little underpowered, here's why.

Boeing 767-300: MTOW ~415,000 lbs.
thrust per engine ~63,000 lbs.

Airbus A330-200: MTOW ~510,000 lbs.
thrust per engine: ~72,000 lbs.

The Airbus weighs like 100,000 pounds more than the 763, yet each engine only makes 10,000 lbs. of thrust more.

I used to work on the groundcrew and have seen both take off, the 763 really gets on it quickly and takes of very fast while the A330 is slow off the start and takes off a bit slower than the 763. If you're all gonna say well it weighs more, bla, bla, bla... When I saw DC-10s take off, they were almost as fast as a 763 and it weighs like 580,000 lbs., so it wasn't underpowered for takeoff. My preference is that I'd rather be in the overpowered aircraft, so it's Boeing for me (if I can help it)  Smile.
 
SailorOrion
Posts: 1959
Joined: Tue Feb 06, 2001 5:56 pm

RE: A380 Underpowered?

Wed Nov 21, 2001 3:15 pm

When comparing aircraft about go-around situations, it is required to compare MLW (maximum landing weights) not MTOWs. Under these circumstances, you really need any little m/s² of acceleration you can get out of the plane, therefore usually N1 can be above 100%, and thrust can be higher than the actual value.

Results:

A380-800: 0.33
A340-300: 0.32
A340-600: 0.40
B747-400: 0.38

Well, here you can see that the A340-600 actually has the highest thrust to weight ratio. Still, both the A340-300 and A380-800 have less power available for go-around maneuvers.

SailorOrion
 
boeing767-300
Posts: 622
Joined: Mon Sep 10, 2001 11:23 pm

Seagull... Lbs And Kgs

Wed Nov 21, 2001 7:51 pm

They are only mixed up because as far as weight is concerned lbs means nothing to me in the metric world (USA excluded) but thrust is like height and although Engines are also quoted in KNs, but being in the transition generations it means more in lbs , a bit like 6ft tall means something and 1.83m does not.

But regardless of that, the result is the same, kilos per pound of thrust. They were all done the same.



 
donder10
Posts: 6944
Joined: Sun Oct 21, 2001 5:29 am

RE: A380 Underpowered?

Wed Nov 21, 2001 8:17 pm

''When you hit severe shear, firewall the throttles, and hang on for dear life while the stickshakers are going off, "efficiency" isn't going to save hundreds of lives. That's how I feel whether I'm in an A-340 or a C-152.''
OSCAR AWARD OF THE DAY!!!!  Big grin Big grin Big grin
 
XXXX10
Posts: 703
Joined: Mon Jan 03, 2000 7:10 am

Whats The Point In Extra Power

Wed Nov 21, 2001 11:14 pm

Surely giving a design more power than it needs will make it in-efficient.

Provided that the A380 can use all of the runways and departure routes that it needs to without payload restrictions there should be no problem.

Perhaps a wing that is able to vreate a steep climb angle is not as good when it gets to cruising height.

It is likely that the A380 will be used from major airfields with lomg runways rather than short fields sorrounded by mountains which may be used by smaller aircraft like the 777 and A330/A340

I know safety is of the utmost importance but the rugaltors will not certify an aircraft if it is not safe.

 
WhiskeyNovembr
Posts: 96
Joined: Fri Nov 09, 2001 6:50 am

RE: A380 Underpowered?

Wed Nov 21, 2001 11:49 pm

XXXX10, you suggest that giving a design more power than it needs will make it inefficient. Having excess power may make it LESS efficient...but not necessarily INefficient. Remember that just because you have the power doesn't mean you have to use it. If, for example, everyone drove their cars around with the accelerator floored, using all available power all the time, efficiency (ie: mileage) would obviously suffer. When driving normally, efficiency is on par with most other cars. Sure, a 3-cylinder Geo Metro would be more efficient, but 99.9% of us opt for a more functional and comfortable vehicle that can actually make it up large hills. That's how I feel about airplanes. To me (and most pilots), a feeling of safety, security, and peace of mind is worth a little more fuel burn.

By the way, I'm not trying to prove you wrong or anything...just offering my point of view on the whole "efficiency vs. power" discussion. Have a good one!

 
XXXX10
Posts: 703
Joined: Mon Jan 03, 2000 7:10 am

RE: A380 Underpowered?

Thu Nov 22, 2001 1:21 am

I agree with what you say but am thinking of the weight of the extra large engines that you will possibly never use at full power.

I think Airbus are talking about an A380-50 which will be slightly smaller but would be used for hot & High fields.

Perhaos that will be the sports version
 
prebennorholm
Posts: 6444
Joined: Tue Mar 21, 2000 6:25 am

RE: A380 Underpowered?

Thu Nov 22, 2001 8:17 am

There are a few more variables than previously mentioned. First of all practically all airliners come with different engine types or subtypes with different thrust ratings. For instance a 340 comes with three different CFM56 engines with ratings from 31.2 to 34k lbs.

The 340 is no sportscar. But those of you who witnessed a very slow 340 climb, did you remember to check the engine type plate before take off?

The 744 has a relatively short span wing, very little more than a 340 which is so much lighter. Wing span means the most for efficiency at slow speed at take off. The 744 must compensate for its short wing span with powerful engines in order to gain its higher take off speed on the same runway.

The 380 has a 50 feet wider wing span compared to the 744. So the 380 - like the 340 - has a quite generous wing span, therefore relatively slow take off speed.

Sure Airbus quad buyers don't pay much attention to climb ability at MTOW. And they are probably right that it doesn't show up on the bottom line if their planes spend 5 or 10 minutes more or less going from zero to 30,000 feet on a 10-15 hours flight. What counts is the overall economic performance.

There is another consideration: Especially the 744 at MTOW has problems to clean up its wing at the 250kts. speed limit below 10,000 feet. Long duration flight with flaps extended means a lot of drag and extra fuel burn.

But the reality is that mostly the manufacturers install the power which the customers want. Most large European and Asian airports are close to sea level. It cals for less take off power needed. Things like Denver and Mexico City etc. do not exist on the other side of the pond. So manufacturers selling to American operators will often have to install more power.

There ain't many Airbus quads sold in America. Maybe because they are less powerful. But if one day Airbus sells quads in America, then they will most likely have to install more power, because that's what the customer needs for his operation profile. At least on the 380 that's no big deal since more powerful RR trent engines are on the shelf ready to be installed when the customer wants it so.

Regards, Preben Norholm
Always keep your number of landings equal to your number of take-offs
 
seagull
Posts: 334
Joined: Sat Jun 30, 2001 5:58 pm

RE: A380 Underpowered?

Thu Nov 22, 2001 12:07 pm

OK. lots of good points. To the poster above who worries about 250 kts below 10k on the 744, the MD-11 climbs at 289kts below 10k, look at the reg, we can exceed 250 if we need to for operational reasons, we are NOT expected to climb with the slats out!

The rate of climb may be a function of power, but the ANGLE of climb is what is the concern on takeoff and also to a great extent on the windshear escape. The lower speeds of the A-380 will net a better angle, and that's how it easily meets Part 25 performance requirements. Cruise climb at lower airspeeds with less drag to overcome with thrust will help as well. This is all more complex than has been indicated here, and I don't have time to respond to all of the posts above, so I'll leave it at that.
 
cedarjet
Posts: 8103
Joined: Mon May 24, 1999 1:12 am

RE: A380 Underpowered?

Sun Nov 25, 2001 4:12 am

I agree that in windshear the more power the better. But no A340 has ever crashed in windshear (or for any reason) and of course they encounter all forms of wx, just like any other airliner. The air disasters I can think of that have been attributed to windshear are: Eastern 727 at JFK, Pan Am 727 at New Orleans, Delta L1011 at DFW. Although I don't know the numbers, the L1011 and TriStar are very sporty, high thrust-to-weight aircraft, much more so than the A340. A good friend of mine who flew 707s and 727s (and Hs748s, bless) always refers to the 727 as a "hotrod". And two have been brought down by windshear. So surely (a) any jet can be sucked into the ground by this phenomenon, no matter how powerful; and (b) avoiding it in the first place is better than doing the whole "firewalling the throttles while the yokes start vibrating"?

I agree the 777 wing is a gorgeous sight to behold, said this here before but from inside the aircraft inflight it looks like the wing of one of those high-altitude Gary Powers spyplanes from the 60s, long and thin and bending upwards at the tips. Like a glider wing.
fly Saha Air 707s daily from Tehran's downtown Mehrabad to Mashhad, Kish Island and Ahwaz
 
megatop
Posts: 336
Joined: Thu May 20, 1999 9:52 pm

To All Of You

Mon Dec 03, 2001 8:04 pm

I agree with prebennorholm and Cederjet.

To all of you: Have you ever tried to takeoff with all 3 types, A340, B777 and B744.

I have tried all 3, on longhaul flights from Malaysia and Singapore to Europe.

I must say I love them all. But what feels the most "slowly" is the B744. It has a very long takeoff roll, and the climb it very gently. The A340 is no rocket, and the B777 at almost MTOW is maby quiker than the A340 but again no rocket.

For me it dos not matter if it's a A340, B777, B747 ect., but which Company it is . My first choice is SIA.

Megatop
 
WhiskeyNovembr
Posts: 96
Joined: Fri Nov 09, 2001 6:50 am

RE: A380 Underpowered?

Tue Dec 04, 2001 2:17 am

Saying the A340 is perfectly safe simply because none have crashed in windshear/microbursts (yet) is like saying an old, bald, frayed tire is safe because it hasn't blown yet. Making that claim is no different than reasoning, "It hasn't crashed yet in those conditions, so it must be immune to them". When it comes to aviation safety, I prefer to think in a proactive manner rather than in a reactive manner.
 
Blackbird
Posts: 3384
Joined: Wed Oct 06, 1999 10:48 am

RE: A380 Underpowered?

Tue Dec 04, 2001 5:30 am


The comment about the A340 not crashing in windshear is false logic. It can definetly crash, it just has been lucky so far.

The L-1011 @ Dallas encountered an unusually brutal microburst. They suddenly gained 23 kts of airspeed, then lost 40, gained 7, then suddenly lost 21 knots.

-Kamarov, Andrea V.
 
prebennorholm
Posts: 6444
Joined: Tue Mar 21, 2000 6:25 am

RE: A380 Underpowered?

Tue Dec 04, 2001 5:49 am

WhiskeyNovembr, sure you have got a valid point. But I think that there are a few more variables to take into account.

1. All long haulers are long haulers only because they haul along a terrible lot of fuel. Almost 50% of MTOW is fuel. When they land most of the fuel has been burned (or in an emergency much of it has been dumped). So when landing the long haulers are in fact extremely powerful compared to many short haulers. So if you count on engine power to fight wind shear, then we should in fact look at the short haulers first. Weaker versions of 739 and 321 would rather be the planes to watch out for, not the 340.

2. As a layman I would not enjoy to fly with an airline which relies on engine power to fight wind shear. Decent procedures prevent surprices. Decent procedures may mean that we sometimes cannot roll off on a taxiway half way down the runway, but we spend two minutes and ten gallons fuel more on taxiing. But it makes me (and the airline insurance companies) sleep better.

3. How fast does a turbofan engine spool up? The wider fan, the more time it needs. I shouldn't wonder if a CFM56-5C on a 340 winds up considerably faster than a PW4000 or such. But if this really was a serious issue, then we should all fly on piston engined airliners. They come to life promptly when the throttle is pushed.

But all this is no more than assumptions from an airline passenger. I wonder if some professional stick and throttle man would spend a moment on validating these assumptions.

Regards, Preben Norholm
Always keep your number of landings equal to your number of take-offs
 
racko
Posts: 4548
Joined: Tue Nov 06, 2001 12:06 am

RE: A380 Underpowered?

Fri Dec 14, 2001 2:15 am

"Saying the A340 is perfectly safe simply because none have crashed in windshear/microbursts (yet) is like saying an old, bald, frayed tire is safe because it hasn't blown yet."

And saying the A340 can't resist windshear because they take off slower than a 777 is like saying a porsche is can break faster than a bmw because it needs 0,5 seconds less for 0-100kph


"The comment about the A340 not crashing in windshear is false logic. It can definetly crash, it just has been lucky so far."

-> The 777 can crash in windshear, it just has been lucky so far.

EVERY plane can crash in windshears. But saying the A340 is more dangerous than other planes is stupid, sorry.

And i don't know how you know about the FMC of an A340, but if you use it for take off you can select a "best economy" mode which make the aircraft t/o and climb slower but more efficent
 
WhiskeyNovembr
Posts: 96
Joined: Fri Nov 09, 2001 6:50 am

RE: A380 Underpowered?

Fri Dec 14, 2001 9:44 am

Hey Racko...you work for the American media, right? I assume so because you incorrectly read my post and then based your argument on the false statement you made up.

Quote from Racko: "And saying the A340 can't resist windshear"...etc, etc

I sure don't remember saying the A340 CAN'T resist windshear. Does anyone else remember me saying that? I suggested that, having less climb performance than other airliners, the A340 WOULD NOT BE AS GOOD at getting out of severe windshear and/or microbursts.

Preben makes some great, subjective points. Once again, his posts are accurate and insightful. Keep up the good work, Preben.







When comparing two aircraft, the one with less climbing ability is more dangerous in severe windshear and/or microbursts. Period.

Have fun trying to prove that wrong.





 
MiG31
Posts: 86
Joined: Mon Aug 18, 2008 10:52 pm

RE: A380 Underpowered?

Fri Dec 14, 2001 10:38 pm

Whats the matter with A380 anyway?
First people think it had not enough doors, then not enough power Big grin whats next?

Kind Regards,

I.T.
 
Skystar
Posts: 1339
Joined: Thu Jan 13, 2000 3:58 pm

RE: A380 Underpowered?

Fri Dec 14, 2001 10:44 pm

MiG31,

Didn't you read my post?
Not enough wing either  Smile

Cheers,

Justin
 
VC-10
Posts: 3546
Joined: Tue Oct 26, 1999 11:34 am

RE: A380 Underpowered?

Fri Dec 14, 2001 11:36 pm

It surpises me that AI ever sell any a/c with all you design "experts" out there.

Regarding the unexiciting T.O.'s you are predicting. Exciting T.O.'s cost fuel - fuel cost's money - where does the money come from? The travelling public.

What do you people want ? Cheap tickets or exciting T.O.'s? All that matters is that the A380 meets the current legislation on performance.
 
VC-10
Posts: 3546
Joined: Tue Oct 26, 1999 11:34 am

RE: A380 Underpowered?

Sat Dec 15, 2001 5:52 am

I saw a 343 take off and I've seen nothing climb slower

Ever saw an A340-300 fully loaded taking off. God bless there is the curvature of the earth.


Do you know if they were doing a de-rated T.O. ?
 
Skystar
Posts: 1339
Joined: Thu Jan 13, 2000 3:58 pm

RE: A380 Underpowered?

Sat Dec 15, 2001 9:25 am

VC-10,

Irrespective of whether the takeoff is derated, the A340s takeoff performance is quite relaxed.

I have not criticised this fact - I like the A340, but I'll happily admit its characteristics that others perceive to be its failings.

Cheers,

Justin
 
MD-11 forever
Posts: 550
Joined: Wed Mar 14, 2001 12:15 am

RE: A380 Underpowered?

Mon Dec 17, 2001 12:48 am

VC-10, I agree with you in every single point! to safe the materials with derated take offs and therefore give more on-wing time to the engines is more important than exciting take off performances! Is anyone of you guys, asking for exciting take-offs, willing to pay extra money for this? An airplane, especially a longhaul one, has to be efficent in the cruising segment of the leg, that's what matters. The go-around performance and as well the take-off performance is safe and ok when a plane gets its airworthiness certificate. If you guys know everything better than the AI engineers, why don't you build your own planes which are more safe and efficent than the actual ones?
Cheers, Thomas
 
dynkrisolo
Posts: 1825
Joined: Mon Feb 12, 2001 12:12 am

RE: A380 Underpowered?

Mon Dec 17, 2001 4:59 am

I'd like to point out a big difference between the A380 and the A343. The A380 has a much lower wing loading than the A343. So, the A380 does not need as much engine thrust per unit weight as the A343.

I wish people would stop defending for the A343. No question that the A343 is certified to meet all the safety requirements. Still, it is a fact that the A343 is an underperformer relative to the competition. The A343 is a compromised design because Airbus wanted the A333 and 343 to share the same wing. This choice practically limited Airbus to only one engine choice, the CFM56. The CFM56 is pushed to the limit for the A343 application. It is far from the most ideal engine for the A343. Just take a look how many new A343 customers Airbus has picked up in the past five years, it's very clear that the A343 is not a very popular aircraft.

Airbus apparently have learned the lesson, that's why the A345/6 will be 30+% heavier than the A343, but the A345/6 engine will be 60+% more powerful than the A343 engine. Not a single growth version of any commercial jets that I know of has that kind of disproportionate thrust-to-weight increase.
 
Skystar
Posts: 1339
Joined: Thu Jan 13, 2000 3:58 pm

RE: Wing Loading

Mon Dec 17, 2001 4:10 pm

Here are some wingloading numbers.

A340-300 (275t)
weight/area
275,000/361.6

=760.51 kg/m2

A380 (560t)
weight/area
560,000/845

=662.72 kg/m2

The A380 has a 12.9% lower wing loading.

I have to retract an earlier calculation that put the A340 with a better wing loading than the A380 - I might have mixed up units or used outdated figures. Having said that, the 380 has a lower power loading than the 340 - the better wing loading will allow the 380 to attain higher cruising altitudes.

Cheers,

Justin

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Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos