BOE773
Topic Author
Posts: 413
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RR Engines Burn More Fuel Than GE.

Fri Jul 14, 2006 8:01 am

According to SFC statistics, Rolls Royce engines burn more fuel than GE engines with comparable thrust. Is it because RR run with a lower pressure ratio than GE?
 
jetlife2
Posts: 182
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RE: RR Engines Burn More Fuel Than GE.

Fri Jul 14, 2006 8:19 am

Well, this will generate a lot of responses! Everyone will have an opinion.

First point to answer, is it true, and based on what data? Are there any unbiased comparisons?

Probably the only people able to make a nearly accurate comparative assessment are the airframers where there are competing engines on the same aircraft. Both GE and RR submit cycle models to the airframer and they are audited for accuracy by the airframer. Then they run them side by side for the same airframe and mission. However the results are usually not made public to both sides. So RR would get the results of their analysis, but not the results for "the other guys".

Others who could make this assessment are customers who get competing proposals during sales campaigns. Fuel burn is often subject to financial guarantees so it is not in the company interest to wildly exaggerate claims. So customer evaluation teams are able to put them side by side and have some level of confidence.

Others are lease companies, and more rarely customers, who actually operate both versions.

So over the years these conclusions become known to all parties in the industry, since after all, this is a small town where everyone knows everyone else's business.

So yes it is broadly true that GE's SFC is better. Some might attribute it to better materials, higher temperatures, better cycle and aero design and more physics based understanding, vs empirical incremental changes.

Some might ask (at the risk of dragging the thread off topic) how this can be true if three spools are better than two. Some might conclude that might not be true after all.

But that would be just one opinion.
My views are not necessarily the views of the GE Company
 
BOE773
Topic Author
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RE: RR Engines Burn More Fuel Than GE.

Fri Jul 14, 2006 8:31 am

RR paid both QF and NZ airlines fuel penalties for the RB211s
on their 747-400s.

The CF6-80C2B1F engine has a SFC of 0.337 LB/HR. on the 747-400.

The RB211-524G and H engines have a SFC of 0.58 LB/HR on the 747-400.

So the Specific Fuel Consumption measured in Lb/HR. of a Rolls Royce
is quite a bit more than the GE engine for the 747-400.

Most RR engines are traditionally heavier and more 'maintenance
intensive' due to their three-spool layout, compared to the simpler
and lighter twin-spool of modern GE and P&W engines. This is also
why RR engines consume more fuel than the competition since a three
spool layout requires more power to drive and runs at a lower pressure ratio.

All four Trent engines (1000-A1, 1000-C1, 1000-D1 & 1000-E1)
for the Boeing 787 series aircraft will have a SFC of 0.506 LB/HR.

I do not have the SFC figures for the four GEnx engines for the 787s-
(GEnx-1A72, GEnx-1B54, GEnx-1B64 & GEnx-1B70).

But I expect the SFC of the GEnx will be lower than the RRs; most
likely in the 0.35 - 0.40 LB/HR range.
 
tepidhalibut
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RE: RR Engines Burn More Fuel Than GE.

Fri Jul 14, 2006 4:30 pm

Quoting BOE773 (Reply 2):
The CF6-80C2B1F engine has a SFC of 0.337 LB/HR. on the 747-400.

The RB211-524G and H engines have a SFC of 0.58 LB/HR on the 747-400.

I'm no expert, but I suspect you're comparing Cruise SFC with Take-Off SFC.
 
Tristarsteve
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RE: RR Engines Burn More Fuel Than GE.

Fri Jul 14, 2006 4:43 pm

Quoting BOE773 (Reply 2):
The CF6-80C2B1F engine has a SFC of 0.337 LB/HR. on the 747-400.

The RB211-524G and H engines have a SFC of 0.58 LB/HR on the 747-400

Try and use some common sense and ask yourself if these figures are true. Would you buy a car knowing that the fuel consumption was 72% higher for the same mission? This would mean that a CF6 engined B744 has 70% more range than an RB211!!!

Try comparing similar figures and start again,
 
manzoori
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RE: RR Engines Burn More Fuel Than GE.

Fri Jul 14, 2006 4:53 pm

That's two threads now you've started bashing RR for no apparent reason... I wonder why?

First off, NO, RR will not end up being a sub-con supplier to GE & PW... for all the reasons explained in the other thread.

Secondly, where do you get these figures from? The three shaft engine design is actually lighter and smaller than the equivalent two shaft design so there goes that argument... I'll give this thread an F+ and a 'Must try harder'.

 Wink

Rez
Flightlineimages DOT Com Photographer & Web Editor. RR Turbines Specialist
 
astuteman
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RE: RR Engines Burn More Fuel Than GE.

Fri Jul 14, 2006 4:58 pm

Quoting BOE773 (Thread starter):

If it helps, it might be worthwhile a) quoting actual figures, and the quoting the reliable source from whence they came, and b) ensuring that you're measuring "like-for-like".

If you're talking engines, it might also be worth "messaging" knowledgeable people like Lightsaber and Widebodyphotog.
They will have very reliable "back-up" sources for comparison.

Hope that helps.

Regards
 
wingscrubber
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RE: RR Engines Burn More Fuel Than GE.

Fri Jul 14, 2006 10:03 pm

Quoting BOE773 (Reply 2):
Most RR engines are traditionally heavier and more 'maintenance
intensive' due to their three-spool layout

Perhaps maintenance on a triple spool is more involved at the overhaul stage than a double spool, but I can tell you first hand that the engineers I spoke to who work on the 777s at Cardiff when I was working there preferred the trent to the GE90, and called the GE90 'Not a very good engine'.
I'd elaborate if I could but my personal experience with these is minimal.
Resident TechOps Troll
 
brendows
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RE: RR Engines Burn More Fuel Than GE.

Fri Jul 14, 2006 10:55 pm

Quoting BOE773 (Reply 2):
The CF6-80C2B1F engine has a SFC of 0.337 LB/HR. on the 747-400.

Cruise SFC for the CF6-80C2B1F is 0.564 lb/hr/lb.

Quoting BOE773 (Reply 2):
I do not have the SFC figures for the four GEnx engines for the 787s-
(GEnx-1A72, GEnx-1B54, GEnx-1B64 & GEnx-1B70).

These engines will have a cruise SFC of about .495lb/hr/lb IIRC.

EDIT: many answers to the first question can be found in this post by Lightsaber Smile
http://www.airliners.net/discussions...general_aviation/read.main/2794875

[Edited 2006-07-14 16:01:04]
 
LMP737
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RE: RR Engines Burn More Fuel Than GE.

Fri Jul 14, 2006 11:06 pm

Quoting BOE773 (Reply 2):
Most RR engines are traditionally heavier and more 'maintenance
intensive' due to their three-spool layout, compared to the simpler
and lighter twin-spool of modern GE and P&W engines.

Actually the RB211 stays on wing much longer than the PW2000.
Never take financial advice from co-workers.
 
RichardPrice
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RE: RR Engines Burn More Fuel Than GE.

Fri Jul 14, 2006 11:42 pm

Quoting BOE773 (Reply 2):

Most RR engines are traditionally heavier and more 'maintenance
intensive' due to their three-spool layout, compared to the simpler
and lighter twin-spool of modern GE and P&W engines.

Everything Ive read on this subject say that the triplespool RR engines are lighter than their twin spool counterparts from GE or P&W because the engine is a lot shorter.

BOE773 - its also good manners to quote your post considering you have lifted it directly and completely from this thread on Airdisaster.com:

http://www.airdisaster.com/forums/showthread.php?t=79049
 
Tristarsteve
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RE: RR Engines Burn More Fuel Than GE.

Sat Jul 15, 2006 2:35 am

Quoting BOE773 (Reply 2):
Most RR engines are traditionally heavier and more 'maintenance
intensive' due to their three-spool layout, compared to the simpler
and lighter twin-spool of modern GE and P&W engines.

I must admit that the Roller has an extra spool. But to call the GE and PW engines simpler is going too far. Just go and look at a CF6 or a CFM56 sitting on a stand and compare it with a RR engine. The huge array of VGVs and VBVs and all their mechanism and actuators, and the HPTCC and LPTCC pipes and control valves that litter the outside of the casings. And the gearboxes hidden deep under the C Ducts while the RR accessories are all under the fan cowl. I dont think you have looked at them

Now a true story. In the mid 90s we looked after 3 L1011 with 22B engines. In the same hangar was a fleet of 5 DC10-10 with CF6-50s. After two years we had changed one engine for a time ex shaft. The others had changed 19 failed CF6 engines. They thought we must be flying them out for maint but NOT TRUE.
All the 8 aircraft were old, the Tristars ex Cathay and the DC10s ex Delta.
 
411A
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RE: RR Engines Burn More Fuel Than GE.

Sat Jul 15, 2006 4:53 am

As far as Rolls Royce three-spool engines being heavier, yes 'tis true, when compared to similar weights of GE engines of the same (or nearly so) static thrust.

By about 1400 pounds, IIRC.

Having said this, generally speaking, the three-spool design is slightly more fuel efficient than its two-spool counterpart...and is also quieter, while at the same time generally having more time on the wing than others, before removal becomes required.

Rollers are REALLY good engines.
 
RichardPrice
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RE: RR Engines Burn More Fuel Than GE.

Sat Jul 15, 2006 5:23 am

Quoting 411A (Reply 12):
As far as Rolls Royce three-spool engines being heavier, yes 'tis true, when compared to similar weights of GE engines of the same (or nearly so) static thrust.

Exactly how true is this? The Trent 900 (14,190lb) comes in nearly 600lb lighter than the EA GP7200 (14,798lb) for the A380, and a quick google around shows similair results for other comparable engines.
 
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Jetlagged
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RE: RR Engines Burn More Fuel Than GE.

Sat Jul 15, 2006 5:44 am

Quoting RichardPrice (Reply 10):
BOE773 - its also good manners to quote your post considering you have lifted it directly and completely from this thread on Airdisaster.com:

Except the thread starter on airdisaster.com kept coming back for more and even came up with this illogical gem:

Quote:
All the data quoted for GE engines is SFC measured at MAXIMUM power in LB/HP-HR.

All the data quoted for RR engines is SFC measured at CRUISE power in
LB/HP-HR.

Maximum power uses more fuel than Cruise power.
So this makes RR SFC even more than GE.

I wonder what planet he's on?
The glass isn't half empty, or half full, it's twice as big as it needs to be.
 
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zeke
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RE: RR Engines Burn More Fuel Than GE.

Sat Jul 15, 2006 6:24 am

Quoting BOE773 (Reply 2):
The CF6-80C2B1F engine has a SFC of 0.337 LB/HR. on the 747-400.

The RB211-524G and H engines have a SFC of 0.58 LB/HR on the 747-400.

From memory the GE has about 4-5000lb less thrust than the 524HT, with a slightly lower MTOW.

The TSFC figures you are using are incorrect, nothing GE has on the market has a TSFC that low, the GEnx on the 748 will not even be that good.

Quoting BOE773 (Reply 2):
Most RR engines are traditionally heavier and more 'maintenance intensive' due to their three-spool layout, compared to the simpler and lighter twin-spool of modern GE and P&W engines. This is also why RR engines consume more fuel than the competition since a three spool layout requires more power to drive and runs at a lower pressure ratio.

Exact opposite of my understanding.

One of the reasons why CX has RB211s on every fleet (330/340/777/747), and last time I looked we were making billions in profit year after year.
We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
 
n8076u
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RE: RR Engines Burn More Fuel Than GE.

Sat Jul 15, 2006 11:06 am

Does anyone know how the P&W engines on the 747 compare to the GE and RR engines, as far as fuel burn and weight? I can only assume it is worse than the other two.  Wink But I am curious, as it is the one I am familiar with.

Chris
Don't blame me, I don't work here...
 
CPDC10-30
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RE: RR Engines Burn More Fuel Than GE.

Sun Jul 16, 2006 2:20 pm

Quoting TristarSteve (Reply 11):
In the same hangar was a fleet of 5 DC10-10 with CF6-50s.

Don't mean to nitpick too much, but didn't the DC-10-10 use the CF6-6D engine? This was the initial version of the CF6 which was later improved upon. I thought the CF6-50 was for the 10-30.
 
Molykote
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RE: RR Engines Burn More Fuel Than GE.

Sun Jul 16, 2006 5:03 pm

Quoting Zeke (Reply 15):
One of the reasons why CX has RB211s on every fleet (330/340/777/747), and last time I looked we were making billions in profit year after year.

And the last time I looked the RB211 wasn't available on most of those airframes! (Perhaps you meant to suggest that the subsequent Trent line of engines was installed on the A330/A340/777?)
Speedtape - The aspirin of aviation!
 
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zeke
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RE: RR Engines Burn More Fuel Than GE.

Sun Jul 16, 2006 8:10 pm

Quoting Molykote (Reply 18):
And the last time I looked the RB211 wasn't available on most of those airframes! (Perhaps you meant to suggest that the subsequent Trent line of engines was installed on the A330/A340/777?)

All the Trents are types of RB211s, eg the 345/6 has the RB211 Trent 500, see the TCDS http://www.caa.co.uk/docs/401/SRG_PRO_1056%20iss5.pdf
We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
 
ReidYYZ
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RE: RR Engines Burn More Fuel Than GE.

Sun Jul 16, 2006 8:56 pm

Quoting TristarSteve (Reply 11):
In the mid 90s we looked after 3 L1011 with 22B engines. In the same hangar was a fleet of 5 DC10-10 with CF6-50s. After two years we had changed one engine for a time ex shaft. The others had changed 19 failed CF6 engines.

Wow, talk about on wing reliability. I admit I'm biased towards RR, and saying that, upper management always said RR was a preferred engine, however the lease costs on GE were less. So it depends on your mission. From personal experience, the RR are prone to vib's (more spinning parts) GE's are prone to bleed probs (more air bleeds off for self accessory cooling/heating than actually goes to the back to promote combustion). RR use of EPR as a measure of actual power output is more accurate vs. GE and N1. As stated before, RR throws most of the accessories under the fan cowl, short of pouring oils, for the GE you open the C-ducts for everything else(PITFA). To be fair, RR is a delicate machine when treated properly, the GE is virtually indestructible in normal ops. According to the AMM, the fly-on damage limits are far greater in terms of blade damage et cetera...but that's what you get for building an engine for the military and then applying to commercial. (or so I've been lead to believe.)
 
GDB
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RE: RR Engines Burn More Fuel Than GE.

Mon Jul 17, 2006 12:46 am

BOE773, if they such shit engines then, why do so many people buy them?
Not all Commonwealth members, not that this ever mattered a damn.

Not bad going for a company that all those 'experts' in the finanicial services wrote off as being bound to exit the civil market in the early 1990's.
And selling such an inferior product too?

What's wrong with this picture?

The very title of the thread gives it away.
 
BOE773
Topic Author
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RE: RR Engines Burn More Fuel Than GE.

Mon Jul 17, 2006 9:29 am

All four Trent engines (1000-A1, 1000-C1, 1000-D1 & 1000-E1)
for the Boeing 787 series aircraft will have a SFC of 0.506 LB/HR/LB.

All four GEnx engines (-1A72, -1B54, -1B64 & -1B70 )
will have a SFC of 0.495 LB/HR/LB.

So the GEnx series will beat the Trent engines in fuel consumption
by 0.011 LB/HR/LB. This fuel savings times two engines over one year will mean significant savings for an airline.
 
Molykote
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RE: RR Engines Burn More Fuel Than GE.

Mon Jul 17, 2006 11:37 am

Quoting Zeke (Reply 19):
All the Trents are types of RB211s, eg the 345/6 has the RB211 Trent 500, see the TCDS http://www.caa.co.uk/docs/401/SRG_PR...5.pdf

Shame on me for not doing research before posting! I'm actually surprised to learn that. My experience is with the RB211-535 only so I had never looked at the TCs for the later Trents (although I was aware that they were quite similar in concept, I didn't know that they held on to the RB211 prefix). Thanks!

Do you know if the Trent 1000 is going to be certificated as an RB211 as well?

[Edited 2006-07-17 04:40:49]
Speedtape - The aspirin of aviation!
 
manzoori
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RE: RR Engines Burn More Fuel Than GE.

Mon Jul 17, 2006 3:57 pm

Quoting Molykote (Reply 23):

Do you know if the Trent 1000 is going to be certificated as an RB211 as well?

I believe we name all our three shaft engines as RB211s.

Rez
 Big grin
Flightlineimages DOT Com Photographer & Web Editor. RR Turbines Specialist
 
RichardPrice
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RE: RR Engines Burn More Fuel Than GE.

Mon Jul 17, 2006 4:25 pm

Quoting Molykote (Reply 23):

Do you know if the Trent 1000 is going to be certificated as an RB211 as well?

Yes, all of the Trent series is derived from the RB211 so they all get the RB211 title as well.
 
Tristarsteve
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RE: RR Engines Burn More Fuel Than GE.

Tue Jul 18, 2006 1:19 am

Quoting BOE773 (Reply 22):
So the GEnx series will beat the Trent engines in fuel consumption
by 0.011 LB/HR/LB. This fuel savings times two engines over one year will mean significant savings for an airline.

Well if that is the case, why does RR sell engines. According to you they are wasting their time.
But airlines buy RR engines so there must be something in it.
By the way where did you get your SFC figures from for engines that are not in service? Are these guaranteed figures. How long are they guaranteed for? I know that RR used to guarantee SFC over the life of the engine, so although it was higher it lasted a lot longer.
Definitely sounds a little suspect to announce SFC figures so accurately when the aircraft hasn't flown!
 
darkblue
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RE: RR Engines Burn More Fuel Than GE.

Tue Jul 18, 2006 5:13 am

Quoting BOE773 (Reply 2):
The CF6-80C2B1F engine has a SFC of 0.337 LB/HR. on the 747-400



Quoting BOE773 (Reply 22):
All four Trent engines (1000-A1, 1000-C1, 1000-D1 & 1000-E1)
for the Boeing 787 series aircraft will have a SFC of 0.506 LB/HR/LB.

All four GEnx engines (-1A72, -1B54, -1B64 & -1B70 )
will have a SFC of 0.495 LB/HR/LB.

So the GEnx series will beat the Trent engines in fuel consumption
by 0.011 LB/HR/LB. This fuel savings times two engines over one year will mean significant savings for an airline.

Not necessarily. Fuel burn rate is driven by both SFC and engine weight. Lower SFC benefits you the most over long flights since you're at cruise a long time, but on short routes, it's not as big of a factor relative to engine weight. Although a GEnx may have lower SFC than the Trent, it is also heavier. Ignoring all other factors, airlines that fly mostly short routes would see more savings with the lighter Trent, even with higher SFC.

GE had even offered Boeing the CF6 for the 787-3. Although SFC is much higher compared to the GEnx, the CF6 weighs much less (~3,000lbs) and would actually be a better choice for the short range 787-3. However, the added cost of certifying an additional engine is what pushed this idea off the table.
 
BOE773
Topic Author
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RE: RR Engines Burn More Fuel Than GE.

Tue Jul 18, 2006 6:18 am

Traditionally, RR engines have weighed more than GE.
 
LMP737
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RE: RR Engines Burn More Fuel Than GE.

Tue Jul 18, 2006 6:46 am

Quoting BOE773 (Reply 28):
Traditionally, RR engines have weighed more than GE.

You might want to look up the wieghts of the GE90 and the Trent.
Never take financial advice from co-workers.
 
BOE773
Topic Author
Posts: 413
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RE: RR Engines Burn More Fuel Than GE.

Tue Jul 18, 2006 7:11 am

All GE series engines prior to the -90 have been lighter than RR engines.

Really, all Trent engines are warmed over RB211 engines without any radical design changes.
 
LMP737
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RE: RR Engines Burn More Fuel Than GE.

Tue Jul 18, 2006 10:12 am

Quoting BOE773 (Reply 30):
All GE series engines prior to the -90 have been lighter than RR engines.

Which GE series engines are you speaking of? Becasue when it comes right down to it there are only two GE and two RR motors you can really compare. The CF-6 vs RB211 and the GE90 vs the Trent. As we all know the Trent is lighter than the 90. Also there's not much weight difference between the RB211 and CF-6 that are mounted on the 747-400.

I'm not sure why you have it in for RR. From personal experience I can tell you both companies make a good engine. Each have their own set of "issues" that crop up from time to time. Let me also tell you that the "warmed over RB211" other wise known as the Trent is an outstanding engine that has served the airlines that have it quite well.
Never take financial advice from co-workers.
 
BOE773
Topic Author
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RE: RR Engines Burn More Fuel Than GE.

Tue Jul 18, 2006 2:09 pm

Taken from a thread about fuel consumption on Air Disasters.

GE90-85B @ 84,700 lb.t. consumes 3.115 kg/s at take-off.
0.282 kg/s at idle.

RR Trent 884 @ 84,950 lb.t. consumes 3.56 kg/s at take-off.
0.31 kg/s at idle.

The GE beats the RR by .028 kg/s at idle.
The GE beats the RR BY .445 kg/s at take-off pwr.
 
RichardPrice
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RE: RR Engines Burn More Fuel Than GE.

Tue Jul 18, 2006 4:11 pm

Quoting BOE773 (Reply 32):
Taken from a thread about fuel consumption on Air Disasters.

I hope you realise that a thread on a forum is not a viable source to quote.
 
AirbusA6
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RE: RR Engines Burn More Fuel Than GE.

Wed Jul 19, 2006 2:48 am

Quoting BOE773 (Reply 30):
Really, all Trent engines are warmed over RB211 engines without any radical design changes.

Hardly!

There are major differences between early Tristar RB211s and later ones on the 747-400 never mind the advances on the various Trents.
it's the bus to stansted (now renamed National Express a6 to ruin my username)
 
BOE773
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RE: RR Engines Burn More Fuel Than GE.

Wed Jul 19, 2006 7:53 am

So what are the major design differences between a Trent and a RB211?
 
Dougloid
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RE: RR Engines Burn More Fuel Than GE.

Wed Jul 19, 2006 9:33 am

We used to call the RR Spey on the G-II the Rolls Royce Spray because it sort of went aloft on a column of thrashed fuel like one of those water powered rockets we had when we were kids.

All kidding aside, what you gotta figure is that SFC is a moving target. The SFC that the manufacturers publish is usually at one or two points along a curve where fuel flow/thrust ratio gets uglier as you pour on the coal so to speak. The limited amount of engine dynamometer testing I've done on Garrett turboprops tends to confirm that. The other point to keep in mind is that SFC is established with an engine that has nice new parts without the aerodynamic profiles degraded and all the sealing elements working as they're supposed to. Depending on the type of engine and how it's been used, SFC numbers will increase until you are temp limited because you're pouring fuel into it trying to chase power from a beat engine. The better index, in my estimation, would be a single number that takes into account power developed, ITT, and fuel flow.
If you believe in coincidence, you haven't looked close enough-Joe Leaphorn
 
RichardPrice
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RE: RR Engines Burn More Fuel Than GE.

Wed Jul 19, 2006 4:36 pm

Quoting BOE773 (Reply 35):
So what are the major design differences between a Trent and a RB211?

The Trent name began with the RB-211-524L when RR realised it had differed significantly from the RB-211 series, and since then all versions have been named 'Trent'.

Both the Trent series and the RB-211 are triple spool, but thats about where the similiarity ends, fan chords are different, size of the turbines are different, placement of turbine blades differ.

To say 'The Trent is a warmed over version of the RB-211' is akin to saying 'The Ford Mondeo is a warmed over version of the Ford Model T'.

No current generation turbofan is a 'new' design, they are all updated variants on older designs - it makes no sense to alter the core design when the concepts dont change.
 
manzoori
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RE: RR Engines Burn More Fuel Than GE.

Thu Jul 20, 2006 6:04 pm

Richard,

I wouldn't rise to it mate, he sounds like a troll!

[sarcasm] Yes Boe773, that's right....all RR 3 shaft engines are basically warmed over RB211-22bs whereas everything GE and PW have produced is unique in every way, and dare I say it even exhausts fresh air unlike these filthy Trents![/sarcasm]

 banghead 

Rez
Flightlineimages DOT Com Photographer & Web Editor. RR Turbines Specialist
 
RichardPrice
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RE: RR Engines Burn More Fuel Than GE.

Thu Jul 20, 2006 6:13 pm

Quoting Manzoori (Reply 38):
I wouldn't rise to it mate, he sounds like a troll!

Both this topic and Modified C-5 To Airfreight The Aurora? (by BOE773 Jul 20 2006 in Military Aviation & Space Flight) were posted on airdisaster.com by user Contrail.

I have great suspicion that they are one and the same people.

From his posts on the other forum, he is anti RR (rabidly so) among other things.

Watch out for the following threads from this user!

http://www.airdisaster.com/forums/se...h.php?searchid=346164&pp=25&page=1
 
manzoori
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RE: RR Engines Burn More Fuel Than GE.

Thu Jul 20, 2006 7:44 pm

LOL!

Thanks for the link! Very amusing!

Cheers!

Rez
 Big grin
Flightlineimages DOT Com Photographer & Web Editor. RR Turbines Specialist
 
BOE773
Topic Author
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RE: RR Engines Burn More Fuel Than GE.

Mon Jul 24, 2006 11:13 am

The four Trent engines (1000-A1, 1000-C1, 1000-D1 & 1000-E1)
for the Boeing 787 series aircraft will have a SFC of 0.506 LB/HR/LB.

All four GEnx engines (-1A72, -1B54, -1B64 & -1B70 )
will have a SFC of 0.495 LB/HR/LB.

So the GEnx series will beat the Trent engines in fuel consumption
by 0.011 LB/HR/LB. This fuel savings times two engines over one year times a fleet of say 20 aircraft will mean significant savings for an airline.

Comments on this specific post please.
 
RichardPrice
Posts: 4474
Joined: Sat Apr 23, 2005 5:12 am

RE: RR Engines Burn More Fuel Than GE.

Mon Jul 24, 2006 4:26 pm

Quoting BOE773 (Reply 41):

Comments on this specific post please.

Evidence for the specific post please.
 
F14D4ever
Posts: 306
Joined: Sat May 07, 2005 3:20 am

RE: RR Engines Burn More Fuel Than GE.

Mon Jul 24, 2006 10:00 pm

Quoting BOE773 (Reply 41):
Comments on this specific post please.

How do you know? 'Cause they told you? How about applying some discernment, just a small adult dose, to your thinking?
"He is risen, as He said."
 
BA787
Posts: 2381
Joined: Sat Jun 03, 2006 9:40 pm

RE: RR Engines Burn More Fuel Than GE.

Mon Jul 24, 2006 10:20 pm

Quoting BOE773 (Thread starter):
According to SFC statistics, Rolls Royce engines burn more fuel than GE engines with comparable thrust. Is it because RR run with a lower pressure ratio than GE?

Just to clarify to the rest of you, this guy has been posting threads such as this in Civ Av and we are all tired of him. He seems to be anti British and is targeting BA, RR, OW, LHR AND BAA

I'd ignore him if I were you
 
HUYguy
Posts: 261
Joined: Thu Apr 13, 2006 9:20 pm

RE: RR Engines Burn More Fuel Than GE.

Mon Jul 24, 2006 11:08 pm

Quote:
He seems to be anti British and is targeting BA, RR, OW, LHR AND BAA

I agree, I was about to say that too. BOE773 - get your facts right before you post, it makes you look a lot less stupid.
 
DH106
Posts: 593
Joined: Wed Jun 15, 2005 5:32 pm

RE: RR Engines Burn More Fuel Than GE.

Mon Jul 24, 2006 11:32 pm

Quoting HUYguy (Reply 45):
it makes you look a lot less stupid.

Allegedly Big grin
...I watched c-beams glitter in the dark near the Tanhauser Gate....
 
darkblue
Posts: 227
Joined: Thu Sep 11, 2003 10:27 pm

RE: RR Engines Burn More Fuel Than GE.

Mon Jul 24, 2006 11:33 pm

Quoting BOE773 (Reply 41):
So the GEnx series will beat the Trent engines in fuel consumption
by 0.011 LB/HR/LB. This fuel savings times two engines over one year times a fleet of say 20 aircraft will mean significant savings for an airline.

And once again, fuel consumption is not driven by just SFC. An aircraft with heavier engines will burn more fuel than one with lighter engines. GEnx weighs more than the Trent.

Funny, I work for GE and I'm on the GEnx program, yet I'm arguing against GE with this troll.

Also, please state a source for your numbers. You can't just blindly compare numbers without knowing all the assumptions that go into them (thrust levels, horsepower extraction, flight condition, etc). I won't discuss what the actual numbers are, but the ones you've listed seem too low.
 
BOE773
Topic Author
Posts: 413
Joined: Wed Mar 08, 2006 6:02 am

RE: RR Engines Burn More Fuel Than GE.

Tue Jul 25, 2006 2:55 am

Quoting DarkBlue (Reply 47):
please state a source for your numbers

GE.
RR.
 
RichardPrice
Posts: 4474
Joined: Sat Apr 23, 2005 5:12 am

RE: RR Engines Burn More Fuel Than GE.

Tue Jul 25, 2006 3:40 am

Quoting BOE773 (Reply 48):
GE.
RR.

Four letters, not including punctuation, does not a source make.

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