LTU932 From Germany, joined Jan 2006, 13864 posts, RR: 51 Posted (6 years 6 months 3 weeks 1 day 14 hours ago) and read 8448 times:
I don't know if this has been discussed before, but here it goes. I was thinking about any possible re-engining of the 747-400 with newer engines to increase service life and also fuel economy. More specifically, re-engining with the Trent 500 Series. I know the 747-400 isn't very old at all, but nevertheless, it's an idea, albeit a hypothetical one. Here are my questions:
1. Is it technically possible to install Trent 500 engines on a 747-400? If yes, what would such a re-engining involve in terms of modifications?
2. Would it be economically viable to perform such a re-engining programme?
3. How would the Trent 560 or 556 impact flight performance and also fuel burn on the 747? Would the Trent 500, at the same certificated MGTOW of a 747 reduce or increase its payload range?
4. How much thrust must the Trent 500 series produce for application on the 747?
Leezyjet From United Kingdom, joined Oct 2001, 4041 posts, RR: 55 Reply 1, posted (6 years 6 months 3 weeks 1 day 13 hours ago) and read 8450 times:
Quoting LTU932 (Thread starter): 1. Is it technically possible to install Trent 500 engines on a 747-400? If yes, what would such a re-engining involve in terms of modifications?
Anything is possible, so I would say yes. If they can install a GE-90 on a 747 then I'm sure that a Trent 500 would not be a problem.
Quoting LTU932 (Thread starter): 2. Would it be economically viable to perform such a re-engining programme?
Maybe in the future, like with the DC-8's and KC-135's being fitted with CFM-56's to extened the life, but it would depend on the cost of the modifications and the savings it would generate over the a/c life span from the point the modifications were done and whether it would be more cost efficient to park the a/c up and but another newer a/c.
Don't know you last 2 questions, that is highly technical info you are asknig for that would take some calculation to do.
"She Rolls, 45 knots, 90, 135, nose comes up to 20 degrees, she's airborne - She flies, Concorde Flies"
N231YE From , joined Dec 1969, posts, RR: Reply 2, posted (6 years 6 months 3 weeks 1 day 9 hours ago) and read 8400 times:
Quoting LTU932 (Thread starter): 4. How much thrust must the Trent 500 series produce for application on the 747?
Well, considering the weakest engine option for the 747-400 is the P&W4052 (Based on info from PW, GE, and RR) putting out 52,000 lbs of thrust, I would assume either that or higher. Because both of the Trent 553 and 556 produce 53,000 lbs or more(RR), the thrust range alone seems possible. However,
Quoting LTU932 (Thread starter): 3. How would the Trent 560 or 556 impact flight performance and also fuel burn on the 747? Would the Trent 500, at the same certificated MGTOW of a 747 reduce or increase its payload range?
I am not sure the weights on the engine, as well as other things into consideration. Being that the Trent 500 series is a newer and more advanced engine, it should be more efficient than the old RB.211's originally developed for the L1011. However, the -524G/H-T is a newer and more highly efficient RB.211 model, so that could also come into play. Someone with a higher knowledge in this field may elaborate better.
JetMech From Australia, joined Mar 2006, 2587 posts, RR: 53 Reply 3, posted (6 years 6 months 3 weeks 1 day 8 hours ago) and read 8365 times:
G'day LTU932 ,
I'm no expert on this sort of thing either, but I will throw in my 2 cents anyway.
Quoting LTU932 (Thread starter): 1. Is it technically possible to install Trent 500 engines on a 747-400? If yes, what would such a re-engining involve in terms of modifications?
As Leezyjet mentioned, a GE-90 was fitted to a 747 for testing. Since a T-500 is much closer in size and weight to the current crop of B744 engines, it would appear to be feasible. The major modification required would be new struts. I suspect that the interface between the strut and wing is the same regardless of engine type, so most of the modification would be to the interface between the strut and the T-500.
Quoting LTU932 (Thread starter): 2. Would it be economically viable to perform such a re-engining programme?
This is more a question of non-technical factors of which I have no experience.
Quoting LTU932 (Thread starter): 3. How would the Trent 560 or 556 impact flight performance and also fuel burn on the 747? Would the Trent 500, at the same certificated MGTOW of a 747 reduce or increase its payload range?
The following is what I presume as the maximum thrust engine option from each of the big three currently powering the B744;
Pratt & Whitney PW4062
63,300 lb (281.57 kN)
Rolls-Royce RB211-524H2-T
59,500 lb (264.67 kN)
General Electric CF6-80C2B5F
62,100 lb (276.23 kN)
RR gives the thrust of the T-556 as 56,000lb (249.1kN), so considering the less powerful engine options as mentioned by N231YE, it would seem that a B744 / T-556 combination would have a very similar MTOW.
My concern is whether RR have optimised the T-556 too much towards the A345 / A346 combination. The typical cruise speed of the B744 is 0.85M, whilst the Maximum Operating Mach Number (MMO) of the A345 / A346 is 0.86M. The B744 also has a higher wing sweep angle of 37.5 degrees compared to the A345 / A346 at 31.1 degrees.
Both of these suggest that the B744 was designed for, and is capable of a higher cruise speed. Since the A345 / A346 is the only current use of the T-500 , RR probably would have optimised it to have maximum efficiency at the typical cruise speeds of these aircraft. If the T-500 was used on the faster B744, these efficiencies (thermal, propulsive) may start to drop off. The end result may be less payload/range despite the engines probably having better fuel efficiency (TSFC?).
Quoting LTU932 (Thread starter): 4. How much thrust must the Trent 500 series produce for application on the 747?
The maximum nominal thrust you can currently get from the T-500 is 56,000lbs (249.1kN). This is not as good as the most powerful options currently available from each manufacturer, but it is probably more than some of the less powerful options, as stated by N231YE.
LTU932 From Germany, joined Jan 2006, 13864 posts, RR: 51 Reply 4, posted (6 years 6 months 3 weeks 1 day 7 hours ago) and read 8346 times:
Quoting JetMech (Reply 3): Since the A345 / A346 is the only current use of the T-500 , RR probably would have optimised it to have maximum efficiency at the typical cruise speeds of these aircraft. If the T-500 was used on the faster B744, these efficiencies (thermal, propulsive) may start to drop off. The end result may be less payload/range despite the engines probably having better fuel efficiency (TSFC?).
So, Basically, it's technically possible but in the end, the engine itself might to be modified extensively then, right? Thus offsetting the economic viability of such a re-engining programme due to the development costs of these modifications. In this case, what could be done to further optimise the engine for higher cruise speeds, like an Mmo of Mach .88 to accomodate for the 744's cruise speed (I'll designate it a Trent 600 series for this hypothesis)?
Basically, yes. The overall economic factors are always the most important issue. As is always the case, anything to do with aircraft seems to be astronomically expensive.
I'm not sure what engine modifications would be needed to optimise for a different cruise speed, but as you say, it may be cheaper to develop a new engine as opposed to modifying an existing one.
Quoting LTU932 (Reply 4): Isn't there a Trent 560 being built, which is supposed to be the engine of the A346HGW?
You are most probably right, I will look it up .
[Edited 2006-11-05 06:48:37]
JetMech split the back of his pants. He can feel the wind in his hair.
A342 From Germany, joined Jul 2005, 4655 posts, RR: 4 Reply 8, posted (6 years 6 months 3 weeks 23 hours ago) and read 8241 times:
Quoting JetMech (Reply 3): My concern is whether RR have optimised the T-556 too much towards the A345 / A346 combination. The typical cruise speed of the B744 is 0.85M, whilst the Maximum Operating Mach Number (MMO) of the A345 / A346 is 0.86M. The B744 also has a higher wing sweep angle of 37.5 degrees compared to the A345 / A346 at 31.1 degrees.
Both of these suggest that the B744 was designed for, and is capable of a higher cruise speed. Since the A345 / A346 is the only current use of the T-500 , RR probably would have optimised it to have maximum efficiency at the typical cruise speeds of these aircraft. If the T-500 was used on the faster B744, these efficiencies (thermal, propulsive) may start to drop off. The end result may be less payload/range despite the engines probably having better fuel efficiency (TSFC?).
I don't think so. The PW4000 and CF6-80C are also used on the A300/310 and 767, which have a cruise speed of only about Mach 0.80.
But I think such a re-engine programme wouldn't be too useful. The Trent 500 is already technologically surpassed by other engines. If one wants to re-engine the 744, a more efficient engine should be used.
Lightsaber From United States of America, joined Jan 2005, 10690 posts, RR: 100 Reply 11, posted (6 years 6 months 2 weeks 6 days 16 hours ago) and read 7965 times:
Could it be done? yes. Will it? Economics will answer that. If it pays to re-engine a JT9D with CF6's... possibly.
Quoting N231YE (Reply 2): Well, considering the weakest engine option for the 747-400 is the P&W4052
But one little chip change fixes that. You're also talking engines slightly customized for very short hop operations. An unusual application on the 747 (The Japanese 744D's).
Quoting JetMech (Reply 3): The maximum nominal thrust you can currently get from the T-500 is 56,000lbs
The maximum current certified thrust is 56k. A little birdie told me that they could be upgraded to 63k (after quite a bit of engineering though). Why maybe this thrust was from Airbus' thrust growth requirement on the A345/346... naaa... I wouldn't ever have seen a document like that.
All engine lines have a thrust growth requirement. E.g., Boeing even has a thrust growth requirement for the GE90-115! Ok, usually there is a minimum time frame given. But the "rule of thumb" is 15% growth in thrust unless the airframer has a target or known "upper bound" (e.g., point at which both the wing at pylon cannot be cheaply reinforced). Rumors are the 777C required 125K thrust growth (unusually low, this is to allow more optimization at the 115K thrust point). Thrust growth requirements are far stricter if there is only one engine option for an airframe.
LTU932 From Germany, joined Jan 2006, 13864 posts, RR: 51 Reply 12, posted (6 years 6 months 2 weeks 6 days 16 hours ago) and read 7952 times:
Quoting A342 (Reply 8): I don't think so. The PW4000 and CF6-80C are also used on the A300/310 and 767, which have a cruise speed of only about Mach 0.80.
But weren't both the PW 4000 and CF6-80 built based on the JT9D and CF6-50 respectively? Those were originally designed for higher speeds, especially on the 747.
Jetlagged From United Kingdom, joined Jan 2005, 2452 posts, RR: 17 Reply 13, posted (6 years 6 months 2 weeks 6 days 14 hours ago) and read 7923 times:
Quoting NZ107 (Reply 7): A 748 would look impressive with them!
A342 From Germany, joined Jul 2005, 4655 posts, RR: 4 Reply 14, posted (6 years 6 months 2 weeks 5 days 16 hours ago) and read 7829 times:
Quoting LTU932 (Reply 12): But weren't both the PW 4000 and CF6-80 built based on the JT9D and CF6-50 respectively? Those were originally designed for higher speeds, especially on the 747.
The CF6-6, the very first version of the CF6, entered service on the DC-10, which also has a lower cruise speed. However, the differences between the CF6-6 and CF6-80 are quite big.
BTW, the CF6-80 entered service on the A300/310 and 767 before being used on the 744, so it was not specifically designed for the 747. The same should apply to the PW4000.
Also, the RR RB-211 first entered service on the L1011 before being used on the 747.
These might just be examples, but I think they show the speed difference between the different aircraft isn't really important.
Nice! I have never seen a picture of a 747 with a 777 engine before! Is there any other photos of the whole aircraft flying with the engine?
Also airbus used there first a340-300 to test the a340-500/600 engine as well as the a380 engine. They also used the left inner engine to perform the tests. Is there any reason why both manufacturers used the same side to test the engines?
Can you say 'Beer Can' without sounding like a Jamaican saying 'Bacon'?
BOEING747400 From United States of America, joined Sep 2001, 319 posts, RR: 0 Reply 16, posted (6 years 6 months 1 week 2 days 5 hours ago) and read 7270 times:
Maybe they could design more unique versions of the Trent 500 series more suitable for the 744 than either 345 or 346? An example would be like Trent 560 (60,000 lbs thrust) for basic 744 and Trent 565 (65,000 lbs thrust) for 744ER. I guess you could also make the Trent 570 (70,000 lbs thrust) for 748 as well. Then the 744 series would have new engines instead of being forced to retire due to old age.
SunriseValley From Canada, joined Jul 2004, 3954 posts, RR: 4 Reply 17, posted (6 years 6 months 1 week 15 hours ago) and read 7184 times:
Seems to me that NZ incorporated a Trent section ( not sure which one) into their RB211's to improve fuel burn. Not sure if they did all their engine inventory or not.
Prebennorholm From Denmark, joined Mar 2000, 6019 posts, RR: 55 Reply 18, posted (6 years 6 months 3 days 14 hours ago) and read 7011 times:
When talking reengining of old planes, then only very few examples have been seen.
Talking about Trent 500 on the 744, then it must be kept in mind that such engines carry a price-tag in the $10M range. Four of them is similar to the price of an all new 737 or 320 plane. There has to be a substantial advantage to make such a program viable.
I am not aware of one single civil jet airliner reengining program where the main driving force was not that otherwise the plane would be doomed for noise reasons, or would be seriously handicapped by hushkits. That counts for the 721 Tay, 722 PT-8-2xx, and the DC-8-6x CFM56 programs.
That a GE-90 can be mounted on a 747 wing for test purposes (as seen in reply #6) proves nothing. It is not integrated with the plane at all. It takes off and lands as a three engined plane - no problem when not heavily loaded - and the GE-90 test engine is during flight test not operated by the flight crew at all. It is operated by a minor army of engine test engineers in the cabin.
The flight crew only has instruments where they can read current N1 speed of the test engine, and then the captain has the authority to let the test engineers shut it down, should it be needed because something else goes wrong on the plane.
To really integrate a different engine with a plane requires an R&D program with costs running into dozens of million $$$.
So there has to be a range of things considered before such a program can be initiated:
- There has to be a very significant efficiency gain, most likely due to the planes otherwise being crippled by noise restrictions or hushkits.
- There must be a substantial number of customers to make the R&D and certification programs viable.
- The planes must have decades of residual lifespan.
I can't imagine that all those considerations can come out with a black bottom line figure for the B744.
Always keep your number of landings equal to your number of take-offs, Preben Norholm
Xv408 From United Kingdom, joined Nov 2006, 52 posts, RR: 0 Reply 20, posted (6 years 6 months 2 days 19 hours ago) and read 6942 times:
Ref the NZ 524G and Trent fit, that is the 524G-T, which uses an HP system that is more or less a Trent 700. Similarly the 524H-T. Significant improvement in efficiency.
Xv408 From United Kingdom, joined Nov 2006, 52 posts, RR: 0 Reply 21, posted (6 years 6 months 2 days 19 hours ago) and read 6938 times:
On the OP, also bear in mind that take-off thrust and cruise thrust are not necessarily directly related, so even though T500 and 524G have similar take-off thrust, the cruise thrust of the T500 may be down some way. So it would have to be run harder, which moves the engine away from it's maximum efficiency. The T500 is also 1500lb heavier than the 524G (assuming the charts are comparing simialr powerplants). This probably reflects in part the much higher bypass ratio of the T500 (7.6 vs 4.3).
JetMech From Australia, joined Mar 2006, 2587 posts, RR: 53 Reply 24, posted (6 years 5 months 2 weeks 2 days 5 hours ago) and read 6530 times:
Well look who's back !
Quoting BOE773 (Reply 23): It would be much smarter to re-engine 747s with modern GEnx powerplants instead of old Trents. There would be much more in fuel savings.
I believe that the RR Trent 1000 is a very new engine design, and of a similar "vintage" to the GEnx. Perhaps it would also make a good alternative to the Trent 500 in the remote possibility that the 744 gets re-engined ?
JetMech split the back of his pants. He can feel the wind in his hair.
25 N231YE: I'd hate to break it to you BOE773, but the the GEnx is no better than the Trent 1000. They both are more advanced versions of existing engines. As a
26 LTU932: I started this thread so we can have a civil discussion with aviation experts on the viability of such a re-engining programme and my questions have b
27 BOE773: I'd expect the latest GEnx to have a higher power/weight ratio than the latest Trent as the former will have more composites. The original post was fo
28 TepidHalibut: Nice to see the GEnx catching up with the RB211. I seem to recall the original RB211-22 had composite wide-chord fan blades, and the 535E4 introduc
29 Litz: A couple years back, I was in MCO, and DL had a 738 parked right next to a 777 ... you could clearly see the engine on the 777 was as large as the wh
30 BOEING747400: I would think that it's more economically and financially viable to produce new 744 aircrafts with entirely different engines from the older GE, PW, a
31 LTU932: What about the wing? Would they have to re-design the wing for it to cope with? Wouldn't this thus also require that the Mmo be increased and other a
32 Baroque: Wonderful analogy, better than that of scratching the swelling of a mosquito bite. I don't suppose there is any point in mentioning to him that there
33 BOEING747400: Yes, I would think that maybe the wing could be modified to become a little larger and have raked wingtips instead. Wouldn't that work in improving t
34 A342: Um, no. Boeing will build the 748 and no other jumbos. And why would you want M0.88 cruise speed ? Nobody needs that. There's a reason why Boeing had
35 Andz: I recall seeing a photo of a BA 737 and 777 which showed this comparison, unfortunately I haven't been able to find it to post it here. This one is p
36 Litz: You know ... that's kinda like driving a SUV ... from the cockpit you can see clear across the shiny top of the airplane in front of you ... - litz
37 FTOHIST: I hate to dredge this thread up from last year--no wait, I do want to dredge this thread up from last year. Most of the quoted text here is not accur
38 Tito: In regards to the original question about Trent re-engining of 747-400. The RB211-524G/H can be retrofitted with the Trent high pressure section makin
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, RR probably would have optimised it to have maximum efficiency at the typical cruise speeds of these aircraft. If the T-500 was used on the faster B744, these efficiencies (thermal, propulsive) may start to drop off. The end result may be less payload/range despite the engines probably having better fuel efficiency (TSFC?).
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naaa... I wouldn't ever have seen a document like that. 
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