I had a quick chat with a Lufthansa 747-8I pilot recently on my way home (I'm still working on a writeup of the flight). Landing in LAX, I asked to go see the cockpit (which I always feel a little stupid doing as a grown man, but screw it), and the crew gratiously invited me upstairs. In the cabin were the captain and the much younger first officer, still shutting the plane down.
The first thing I noticed is the cockpit looked rather old. I was expecting a much more drastic update from the 744, but I couldn't really tell the difference.
The captain was friendly but seemed disengaged from his job (as opposed to the KLM pilot I talked to last year who loved talking about the MD-11). He didn't know anything about a top off order, and he didn't even know how many 748s were in the fleet. I pretended like I didn't either. I asked him about efficiency, and he said the fuel burn was about the same as the 744, and the efficiency was due to the airframe stretch and the additional passengers.
I've heard two stories on this subject. One Lufthansa 748 pilot on Airliners.net has said that the 748 uses noticebly less fuel on a stage than the 744, but this pilot said it's about the same. If it is the latter, it's disappointing. I would expect the 748, with it's four state of the art GEnx-2B engines, to burn less fuel than the old 744 engines. Otherwise, what was the point of the new engines? If they have to work harder to carry the stretch, that seems like a bad return on the more efficient engines.
The first thing I noticed is the cockpit looked rather old. I was expecting a much more drastic update from the 744, but I couldn't really tell the difference.
The captain was friendly but seemed disengaged from his job (as opposed to the KLM pilot I talked to last year who loved talking about the MD-11). He didn't know anything about a top off order, and he didn't even know how many 748s were in the fleet. I pretended like I didn't either. I asked him about efficiency, and he said the fuel burn was about the same as the 744, and the efficiency was due to the airframe stretch and the additional passengers.
I've heard two stories on this subject. One Lufthansa 748 pilot on Airliners.net has said that the 748 uses noticebly less fuel on a stage than the 744, but this pilot said it's about the same. If it is the latter, it's disappointing. I would expect the 748, with it's four state of the art GEnx-2B engines, to burn less fuel than the old 744 engines. Otherwise, what was the point of the new engines? If they have to work harder to carry the stretch, that seems like a bad return on the more efficient engines.
The pilot is about right. The 747-8 has a double-digit (~10%) fuel burn improvement per passenger, because it has roughly 10% greater capacity (seat count) compared to the 744. Also the increase in cargo capacity is significant, which figures into the better efficiency claim, too.
ReplyDelete747-8 is much heavier than 747-400, so engines have to be better if fuel burn is the same. Some better performance is from new wings and other aerodynamic changes.
ReplyDeleteOk, well what if they would have just taken the 744 frame and put the four new GEnx engines on it. Then wouldn't those engines have operated much more efficiently than the old engines and still gotten the same 10% improvement? So then what is the purpose of the stretch? To me, in that light, it seems like the performance improvements on the 748 are underwhelming. Considering the new wing, new engine, and stretch, you'd think they all work together for a large efficiency improvement. But if one drags down the improvement of another (ie the stretched frame making the improved engines work harder), that's disappointing.
ReplyDeleteThey stretched it to "fight" with A380 and make better performance for freighter version. Without stretch, 4 engines in these times would be meaningless. 777-300ER isn't much smaller from 744 and with 2 engines is much cheaper for operator, can fly as far as 747 and carry more cargo. Boeing knew it that 747-8 won't be long live in times when planes like 777-300ER and 777X are possible to build. So they didin't invest in CFRP fuselage or any new VLA project. 787 Dreamliner program made new wings for 747-8 possible without much cost, the same with engines.
DeleteLooked around a bit for more specific information on this subject. It appears LH has high praise for the aircraft. Quoting from http://www.lufthansagroup.com/en/press/news-releases/singleview/archive/2014/february/11/article/2793.html:
ReplyDelete"... To put it in numbers: the 747-8 is 15 per cent more fuel efficient than its predecessor model, the 747-400, which translates to 15 per cent less CO2. Altogether, in terms of its capacity, range and operating costs, the new jumbo is a very economical aircraft. ..."
According to the discussion here:
http://www.airliners.net/aviation-forums/tech_ops/read.main/318344/
748 is about 3% better per trip (which is why the pilot did not notice a drastic reduction) and 10%+ better per seat. LH (above) likely used 12% as the second number, adding the two to reach 15%.
On a per cabin space (floor square-footage) basis, LH"s 748 is actually 19% (3%+16%) better than 744. Their 748 configuration is not as dense as their 744's.
The MTOW of 748 is about 13% higher than that of 744.
Might that 748 have been one of the early batch, which was heavier and before the engine and wet tail mods? Latest batch should do better.
ReplyDeleteI think you have hit on an important point of why the 748i is not selling better. I would like to see Boeing go ahead with Project Ozark and get more efficiency out of the 748. This might include more aero mods of the wing to fuselage fairing, further weight reductions, and increased range.
Hear hear. It was D-ABYL actually though, which according to my chart was the "first 747-8I with tail tank enabled, new engines, lower weight, and new FMC directly out of the FAL"
DeleteI thought I replied to this back when it was first posted, but I must have forgotten to actually do it.
DeleteI chatted a bit with the Captain of my flight last summer from ORD to FRA after we had landed. We had flown on D-ABYA, and he relayed to me his experiences, stating that the new frame was much more responsive and easier to fly. He said that he did like the fact that the cockpit was kept essentially unchanged to allow for the easy transition, and that other than the actual feel of flying the plane, not much was different, and thus very little training was needed to switch over.
In terms of efficiency, he had mentioned that he had also flown PIP'd frames, and that he did notice some improvement there between those frames and the pre-PIP versions. He also noted that even the older -8 frames were more efficient on a trip cost basis than the -400s, and that this became more pronounced the longer the route was. When I asked about unit-costs, he stressed that this was a difficult number to really put in context, since the planners had clearly put a higher percentage of space to the premium cabins, thus making the overall passenger density a bit less for the frame. He said that the revenue generated was what they cared about much more, and while anecdotal, his observations were that the frame was doing a good job in that respect.
Overall, a very nice, if relatively short discussion, and a fun way to end my first flight on the 747-8. They even let me take pictures in the cockpit and in F and J, going so far as to let me sit in the F seat and having the purser take a pic of me in it. :-)
Ouch! If that's what D-ABYL could do, the original batch must have caused consternation at LH!
ReplyDeleteAnother thought; might Boeing offer a 748 with the smaller top of the 744? It would be tons lighter and could fly hundreds of miles farther, or burn rather less fuel. I recall Emirates for one was interested in longer range at one time.
I fly 747-8F currently. In cruise, the fuel burn is very similar to 744F. The difference being that the -8F is carrying about 16% more payload than the -400F. I noticed the -8F climb out is noticeably more efficient than the -400. I can't say the same for the descent. The -8F uses a power on descent which, if anything, burns more fuel but starts much further out. I think the trip costs on the -8F are about the same as the -400F, but the extra payload is basically carried for free minus the more expensive cost of ownership. Oh, the PiP has noticeable less fuel burn, at least 2% or more. They run about 20-30 degrees Celsius cooler than the old engines.
ReplyDeleteThanks for the perspectives. Makes sense, the 50 year old basic design is warmed over with new engines but more weight. In many ways, the 777 is a more formidable competitor to the 748 than the A380, and Boeing couldn't justify adding more technology and cost to its classic passenger airliner.
ReplyDeleteOn the other hand, the freighters still have a unique niche, and I'd like to see at least one more upgrade. I could imagine GE wringing a couple more percent out of the engines, and Boeing adding longer wings with folding wingtips, plus more composite structures.
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