Airbus 340-300. Nice plane to be a passenger but..

[nthach]

Originally Posted By: Astro14


So, the 340, from a customer perspective. I've flown on British Midlands and Lufthansa A340s. I found the seat pitch intolerably tight. Worse than anything I've ever been on. This was mitigated on BMI because I was rebooked on them while and they gave me an empty pair of seats by the window. On Lufthansa, the Flight Attendants were great, but man, was the seat tight...

The A340 is slow, and underpowered. By deciding to go with 4 engines, those engines are small. Consider: because the airplane has to be able to get airborne on 75% power (engine failure on takeoff requirement), when all 4 are running, it's got 33% more power than the minimum. A twin, like the 777, has to be able to get airborne on 50% power (engine failure on takeoff), so, when both are running, it's got 100% more power than the minimum. Make sense?


I would have thought the A340-500s with Rolls-Royce Trent engines would be more powerful than the -300 version with CFM56 engine, wasn't the latter made more for fuel economy on medium-haul flights(seeing how Air France and Cathay Pacific used them)?

 

[Astro14]

Originally Posted By: nthach
Originally Posted By: Astro14


So, the 340, from a customer perspective. I've flown on British Midlands and Lufthansa A340s. I found the seat pitch intolerably tight. Worse than anything I've ever been on. This was mitigated on BMI because I was rebooked on them while and they gave me an empty pair of seats by the window. On Lufthansa, the Flight Attendants were great, but man, was the seat tight...

The A340 is slow, and underpowered. By deciding to go with 4 engines, those engines are small. Consider: because the airplane has to be able to get airborne on 75% power (engine failure on takeoff requirement), when all 4 are running, it's got 33% more power than the minimum. A twin, like the 777, has to be able to get airborne on 50% power (engine failure on takeoff), so, when both are running, it's got 100% more power than the minimum. Make sense?


I would have thought the A340-500s with Rolls-Royce Trent engines would be more powerful than the -300 version with CFM56 engine, wasn't the latter made more for fuel economy on medium-haul flights(seeing how Air France and Cathay Pacific used them)?


While the Trent is powerful - the four-engine version of the airplane still has LESS TOTAL THRUST than the two-engine version of the airplane for the reasons above.

You don't buy a lot more engine than you need on an airliner. That just cost $$ and fuel burn....the Trent allowed the stretch and weight growth of the -500 and -600 (IIRC) and Airbus had to further upgrade the landing gear with a DC-10-30 style middle gear, which looks silly but is needed...

 

[Astro14]

Originally Posted By: nthach
Astro,

Since Air France/Lufthansa/Qantas(who also had a well-known engine failure as well) aren't doing too great with this plane and Emirates held off on ordering more at the Paris Air Show and even asked Airbus if the changes in the A380 Plus are going to be incorporated into the planes they have on order, is the A380 program a red herring for Airbus if wasn't for the Middle Eastern and the lone Asian operator(Korean Air) propping it up?

Boeing isn't going too great on the 747-8 passenger version, looks like it's mostly used for freight. Is there a significant difference in the 744 vs the 748 besides the obvious like engines, fuselage extension and some trickle-down from the 787?


The 747-8 has a lot of changes, new engines, some fuselage tweaks, and all-new wing. Systems remain similar to the -400. It's a much better airplane than the -400 in burn, capacity, everything, but its own worst enemy is the 777-300ER, which still burns less per seat-mile than the -8. Which is too bad, I love the 747...

The A-380 is an overpriced, overweight (by 100,000 lbs from design) pig that doesn't perform nearly as well as promised. A giant strategic miscalculation by Airbus. If it weren't for the ME 3 airlines, AB wouldn't have even broken 100 orders on it. They needed to sell 250 just to break even on the R&D and that number is in jeopardy now as airlines are canceling orders and ending leases early. It's also ugly. In person, it's just bulbous and ugly. Emirates wanted -380 NEO design and development work done before they took any more deliveries, and Airbus wanted firm orders to do the NEO work. Catch-22...

The -380 is built on the premise that the future of the airline industry is massive lift from hub to hub. That's not working out, except for the heavily subsidized, state-owned ME 3 carriers. Everyone else is starting to fly point to point in long range, fuel-efficient airliners, and the biggest seller right now in big long range airplanes? 777-300ER...but the A350 looks to be an impressive performer with a long backlog of orders. For the sake of Airbus, that airplane needs to be a huge seller. All accounts are that it performs as promised and is a very good airplane. DAL just took deliveries. They're very excited about the jet's potential.

The other advantage of the 777-300ER is the commonality of type-rating/training and spare parts. It's the same flight deck as the 777-200. So, you expand your fleet and lift without the huge (and they are huge, in the billions for a company like UAL) cost of a new fleet type. It's a great airplane and a great fit for nearly every airline in the world that already operates the 777.

 

[oil_film_movies]

Originally Posted By: PimTac
I thought I would pick the brains of the experts here. The Airbus 340-300. I had the experience of riding on these a few times across the Pacific. Nice for couples with the two seat window aisle. The only downside? They were horribly slow. I had a few occasions flying from Manila to San Francisco on these. They added 2.5 hours at least to the flight which was long enough. I would always groan if I saw one parked at our gate instead of a 744 or a 777.
Was it purely the engines or some other factors that slowed this bird down?
I'm happy now riding the 787 across. Much faster.


I'm seeing MMO figures at only 5% difference between the A340-300 and 787.
A340 MMO is 0.86
787 MMO is 0.90
Service ceilings look similar, BTW.

That 2.5 hour time extension you experienced could have been just because the jet stream was not in the right place on that trip or some. Winds matter.

Originally Posted By: A310
A340-300 cruises around .79 -.81 depending on the operators cost index. The 747,777,787 cruises and .85-.87 again depending on the operators cost index. Airbus has addressed this with the A350 and increasing the cruise to .85-.87.

I suspected operators were cruising way less than the A340's MMO for fuel economy purposes.
So your saying they don't have to reduce speed too far below the 787's MMO then?

I might need to cross-check those MMO figures from other websites....
Anyway, here is a couple:
http://www.flugzeuginfo.net/acdata_php/acdata_a340_300_en.php
http://www.flugzeuginfo.net/acdata_php/acdata_boeing_7878_en.php

 

[oil_film_movies]

Another source, modernairliners.com, list typical cruise speeds for the A340-300 vs. 787:
A340 M=0.82
787 M=0.85
(at about the same altitude)

Maybe the airlines do try to cut the Mach number on the A340 down another notch to get some more fuel savings like user "A310" said above.
That small difference though is just around 5% typically, so most of the slowness PimTac experienced I'll bet was indeed from winds aloft on specific trips.

 

[Astro14]

MMO has little to do with the most efficient cruise speed, any more than redline on the tachometer tells you what RPM to drive on the highway. Cruising near MMO drives fuel cost WAY up. When you're burning 200,000# of fuel on a long range flight, a few percent savings in fuel is TONs of fuel, and when prices are high, as they may have been when he was flying, that's thousands of $$.

Best cruise speed is a matter of weight, temperature, altitude, winds, crew cost, fuel cost and engine type (for airplanes with multiple engine options).

And Airbus airplanes, with very straight wings, often do better to cruise slowly, down at .79, particularly if fuel is expensive relative to crew. The 747 was happy to cruise fast, with relatively little penalty. Just look at the 40 degree leading edge sweep on its wing: built for speed.

And yes, the winds matter. We optimize route for wind, either to take advantage or to avoid. If the tailwinds just aren't there, and the typical plan includes 100 knots, you're just never going to make that up...

 

[4WD]

If 340's were money makers there would be more out there - and they did not have the testosterone sales boost the A380 got ...
I used to take SQ37 - one of the longest flights. The airline was trying to make money putting 100 business class seats (and no other) in an A340 - never once did I see the plane full. It was the calmest boarding of any plane I have flown in - and I have been on everything mentioned in this thread ...
Again, it was great for the passengers - but was it about making money or claiming to have the two longest flights,

 

[oil_film_movies]

Originally Posted By: Astro14
MMO has little to do with the most efficient cruise speed, any more than redline on the tachometer tells you what RPM to drive on the highway

Glad you pointed that out. Some may not understand MMO as a speed limit. The MMO data was the first data I found quickly, and would indicate the capability, the potential, of the aircraft to fly fast, which was the question originally. My next post had typical cruise Mach which would always have a small margin, usually around a delta .05 Mach, between MMO and cruise speed.

Although your car-RPM analogy is way off since jets cruise very close to MMO, yet you wouldn't cruise at 5800 rpm in a car with a 6000 rpm redline, not that close typically! Nurburgring, yes. I was just looking at the Sequence IIIG test the other day, and notice they run an old Buick 3.8L V6 hard at 3,600 RPM (126 hp) for 100 hours straight, quite a workout, and still well short of its 5000 rpm redline.

Originally Posted By: Astro14
And Airbus airplanes, with very straight wings, often do better to cruise slowly, down at .79, particularly if fuel is expensive relative to crew. The 747 was happy to cruise fast, with relatively little penalty. Just look at the 40 degree leading edge sweep on its wing: built for speed.

Wing sweep increases fuel burn (lower aspect ratio, subsonic). We aero engineers have to optimize everything based on the goals: Do we put in more sweep to fly faster, or go with a more efficient aspect ratio (less sweep), choosing to put a sharper edge on the leading edge of the wing to partially compensate for the lower sweep?

It looks like the Airbus engineers were stuck with using 4 engines as a design constraint, with their attendant extra skin friction nacelle drag, and chose to increase fuel economy by having a higher aspect ratio, at the cost of a lower MMO and cruise. Of course, airlines also like speed, so the trade-off optimality varies day by day.

 

[Astro14]

Yeah, we had a whole cost index discussion in another thread...

And we adjust that in real time to adjust for unanticipated changes in operational considerations, E.G. winds not as planned, late off the gate, ATC delays, passenger connections (yes, we DO care, but we can't work miracles).

My analogies are often simple, though I understand the complexities, because aviation is complex and inaccessible to those outside the industry or profession. Trust me, I know the limitations of using analogy - but I'm often constrained by typing on my iPhone, like now, and I have to get to the point so that the majority of forum readers connect.

Cheers,
Astro

 

[Astro14]

Oil_film - if you're interested, you might find some useful discussion in this thread: F-14 Questions answered
And this one What's it's like to fly an airliner

Cheers,
Astro

 

[DeepFriar]

As if to prove the old saying that it is an ill wind indeed that does not blow somebody some good Airbus continues to flog off-lease and otherwise returned 340's for use as VVIP aircraft. It's unpopularity has apparently made the price bearable for the one tenth of 1%. Less cycles in that role and "low" purchase prices mean the overall cost is more easily endured I guess. Makes some sense though in a world where a BBJ fresh out a completion center is $100-120M. You may go "slow" in a 340 but brother you are going in style.

 

[oil_film_movies]

Originally Posted By: oil_film_movies
Another source, modernairliners.com, list typical cruise speeds for the A340-300 vs. 787:
A340 M=0.82
787 M=0.85
(at about the same altitude)


Just to follow up on what myself and user 'A310' said in previous posts here, there is typical difference of about 0.05 Mach = 28 mph @ 30k ft altitude.
So the A340 is going about 28 mph slower than a typical 787 cruise speed.
It can be seen in the "race" video, an a340 racing a 787:

 

[DeepFriar]

Great video! Is it just me or does the nose section appear slightly bulbous in comparison to the fuselage aft of it?

Imagined conversation in the 340 cockpit - You ever get the feeling you're being watched?

 

[oil_film_movies]

And keep in mind that 28 mph difference is at about 550 mph, similar to us getting passed on the highway doing 70 mph while the the car passing us is doing 73 mph, definitely noticable but a gradual thing.

Originally Posted By: DeepFriar
Great video! Is it just me or does the nose section appear slightly bulbous in comparison to the fuselage aft of it?

Got to be lighting. This picture shows the curvature meeting the barrel fuselage sections.