An Airbus-owned A340 has embarked a 75 flight hour test programme for the Pratt & Whitney PurePower PW1000G geared turbofan (GTF) engine.
The initial test flight for the engine demonstrator launched this afternoon from Toulouse. The A340 was still airborne as this article was published.
"Demonstrating the geared turbofan technology throughout its entire operating envelope using the Airbus A340 flight test aircraft will provide us with valuable installation and operating data to further evaluate the performance of the new engine architecture," says Todd Kallman, president, Pratt & Whitney Commercial Engines.
Clydenairways From Ireland, joined Jan 2007, 175 posts, RR: 0 Reply 2, posted (1 year 1 month 1 week 20 hours ago) and read 11000 times:
Quoting WINGS (Thread starter): One has to wonder what would have been if PW had delivered on their promise in the late 80's for the original A340-200/300.
If i remember correctly is was called the SuperFan.
Keesje From Netherlands, joined Apr 2001, 9843 posts, RR: 51 Reply 3, posted (1 year 1 month 1 week 19 hours ago) and read 10929 times:
I believe this engine has a sub optimal core engine (mainly compressor). The test is to understand the technology so a prediction can be made if a better core is equiped with the GTF technology..
AA777223 From United States, joined Feb 2006, 809 posts, RR: 9 Reply 6, posted (1 year 1 month 1 week 15 hours ago) and read 10285 times:
On P&W's website, they show pictures of the engine airborne on a 741(2?). It is an ugly little engine, eh? Kinda ungainly and oddly shaped. It is stranged how is seems to have a band around its mid-section and then the fairing/vane coming out of the back is oddly shaped. Kind of reminds me of the initial RR RB211s that had the vane coming out of the back, a la 742/3 and EARLY 752s. I understand that not many of these engines were produced before the design was changed to obviate the thrust vane. I might be wrong though.
I realize this in no way afffects the functionality of the engine, just an observation...
DocLightning From United States, joined Nov 2005, 7122 posts, RR: 44 Reply 7, posted (1 year 1 month 1 week 15 hours ago) and read 10261 times:
Quoting AA777223 (Reply 6): It is an ugly little engine, eh? Kinda ungainly and oddly shaped.
I was noticing that, too. But... on the front view did you see how much clearance there is around the core? I think the bypass ratio might even be larger than the 777's. I wonder what it is.
YULWinterSkies From Canada, joined Jun 2005, 1477 posts, RR: 7 Reply 10, posted (1 year 1 month 1 week 14 hours ago) and read 9737 times:
I guess the regular A340s will not be re-engined; therefore, why are these still being developed? Which new aircraft are they supposed to equip? A350 & 787? I was under the impression that P&W had left the large commercial jets sector, apart from the Engine Alliance and IAE joint projects.
DocLightning From United States, joined Nov 2005, 7122 posts, RR: 44 Reply 12, posted (1 year 1 month 1 week 13 hours ago) and read 9091 times:
Quoting YULWinterSkies (Reply 10): I guess the regular A340s will not be re-engined; therefore, why are these still being developed?
This engine is a prototype for a GTF. It is the first large, modern GTF ever designed. It is not, so far as I know, designed for any current or planned airliner.
When you do an engine test, you always want to use a plane with at least 4 engines so that if the test engine fails, you still have the other three engines to use and it's not an emergency. If you used a 777 as the testbed and the GTF failed, you'd have to land immediately. The B52 was the testbed for the first generation of 747 engines for that very reason (among others).
Using what they have learned from this program P&W will no doubt begin to work on optimizing the design for this class of engine so that they can begin to offer it for commercial use. This prototype will never see commercial service; it isn't meant to.
WunalaYann From Australia, joined Mar 2005, 2839 posts, RR: 51 Reply 16, posted (1 year 1 month 1 week 10 hours ago) and read 7484 times:
Quoting SXDFC (Reply 15): Pardon the ignorance, but can someone explain to me what exactly a Geared Turbo Fan engine does, as well as the benefits and the cons to it as well.
Add me to the list of laymen.
Would "geared" imply some sort of differential increasing or reducing thrust for the same rotation speed of the shaft?
PITIngres From United States, joined Dec 2007, 327 posts, RR: 5 Reply 17, posted (1 year 1 month 1 week 10 hours ago) and read 7472 times:
Quoting SXDFC (Reply 15): Pardon the ignorance, but can someone explain to me what exactly a Geared Turbo Fan engine does, as well as the benefits and the cons to it as well.
There have been various threads on this. Briefly, the issue is that the fan has heretofore been driven on the same shaft as the low-pressure turbine. It turns out that this means that for larger fans, the fan is running faster than optimum (or equivalently, that the LPT is running slower than optimum). By putting a gear drive in, the fan can be made larger and still run at an appropriate speed, without slowing the LPT down. You get increased efficiency since you can run a larger fan and get a larger bypass ratio and still maintain efficiency in the core. The downside is that running all that power thru a gearset is devilish hard to do reliably, and the gearing adds weight.
There are engine guys around who can probably explain it better, but that's how I understand it.
Bravo1six From Canada, joined Dec 2007, 270 posts, RR: 1 Reply 18, posted (1 year 1 month 1 week 10 hours ago) and read 7472 times:
Without getting too techinical (and someone far more technicial than me can correct me), in a standard turbofan the front fan is directly linked to the engine and thus turns at the same speed as the engine and all the other compressors.
In the GTF there is a gearbox to the front fan which allows it to turn at the optimum speed to generate the most efficient thrust for a given engine speed. It also allows the front fan to be a lot larger than an equivalent standard engine, allowing for greater bypass ratios without increasing the actual diameter of the engine to too great an extreme.
That's my understanding - others please correct me if I got it wrong.
PresRDC From United States, joined Jul 1999, 474 posts, RR: 1 Reply 21, posted (1 year 1 month 1 week 7 hours ago) and read 6696 times:
Quoting YULWinterSkies (Reply 10): I was under the impression that P&W had left the large commercial jets sector, apart from the Engine Alliance and IAE joint projects.
Nope. P&W is just being selective in the new programs it launches, partially due to previous programs that were not commercially successful and partially because UTC limits the amount of negative margin they can take in a given year (recall that an engine is sold at such a discount that it needs to be recorded as a loss when it is sold).
The goal now is to demonstrate and prove the technology so that airlines begin pressuring Airbus and Boeing to go ahead with their NGSA programs, while, in the meantime, selling as many MRJs and C-Series aircraft as possible.
474218 From United States, joined Oct 2005, 3745 posts, RR: 1 Reply 23, posted (1 year 1 month 1 week 7 hours ago) and read 6443 times:
Quoting DocLightning (Reply 12): When you do an engine test, you always want to use a plane with at least 4 engines so that if the test engine fails,
I seem to remember the RB-211 being test flown on a VC-10, where they removed both port Conways and replaced them with one (1) RB-211. Leaving only the two starboard Conways in case of an emergency.
DocLightning From United States, joined Nov 2005, 7122 posts, RR: 44 Reply 24, posted (1 year 1 month 1 week 6 hours ago) and read 6265 times:
Quoting 474218 (Reply 23): I seem to remember the RB-211 being test flown on a VC-10, where they removed both port Conways and replaced them with one (1) RB-211. Leaving only the two starboard Conways in case of an emergency.
Yes, but TWO engines. Not one. You wouldn't want to try this same trick with, say, an A330. This engine has never flown before. You have no idea what it's actually going to do.
F14D4ever From United States, joined May 2005, 316 posts, RR: 4 Reply 25, posted (1 year 1 month 6 days 22 hours ago) and read 4290 times:
Quoting WunalaYann (Reply 16): Would "geared" imply some sort of differential increasing or reducing thrust for the same rotation speed of the shaft?
Specifically, the gearbox allows the fan to turn at a different speed than the low pressure turbine, so that those components can turn at their optimum speeds. (Remember, it is generally desirable to maximize thrust for a given engine configuration.)
Quoting Bravo1six (Reply 18): ... in a standard turbofan the front fan is directly linked to the engine and thus turns at the same speed as the engine and all the other compressors.
You were okay until you went overboard with "all the other compressors". In a turbofan engine, there are at minimum two shafts, with a minimum of two compression components and their associated turbines. The two shafts, hence the two turbines, do not turn at the same speed. The intent of the geared fan is to allow the fan to turn at a speed lower than either of the turbines.
Typhaerion From United States, joined Jun 2005, 615 posts, RR: 4 Reply 27, posted (1 year 1 month 6 days 21 hours ago) and read 4200 times:
I was going to ask a question but answered my own. I figured I would ask and answer it publicly for everyone's edification.
I wondered what the thrust rating of that puppy was in comparison to the CFM56 it is replacing.
I will list it by plane type for comparison purposes, all thrust measured in lbs:
737-600/700/800/900/BBJ:
CFM56-7B: 18.5k - 27.3k
PW1000G: 17k - 23k (largest rating listed so far, not designed for type)
A319 A320:
CFM56-5A: 22k - 26.5k
PW1000G: 17k - 23k (largest rating listed so far, not designed for type)
A318, A319, A319CJ, A320, A321:
CFM56-5B: 22k - 33k
PW1000G: 17k - 23k (largest rating listed so far, not designed for type)
A342, A343:
CFM56-5C: 31.2k - 34k
PW1000G: 17k - 23k (largest rating listed so far, not designed for type)
737-300/400/500:
CFM56-3: 18.5k - 23.5k
PW1000G: 17k - 23k (largest rating listed so far, not designed for type)
KC-135R, C-135R, E-3, KE-3A, E-6A, DC-8 Super 70:
CFM56-2: 22k - 24k
PW1000G: 17k - 23k (largest rating listed so far, not designed for type)
The PW1000G comes in two ratings (as listed by their website): One for the MRJ rated at 14k - 17k, and one for the CSeries rated at 17k - 23k.
So it looks like the current design parameters are not quite big enough for the A320 or 737NG type aircraft, yet. I dont doubt that they could be. And I wonder what the rated output of the test engine was on that A346, given that the Trent 500 that normally sits in that spot is either rated at 56k or 60k (if the test bed is a HGW version).
I make that point because she is already almost operating on three engines given that the PW1000G is less than half of the normal Trent 500 at max thrust. Cruise would not be a problem, and she wont be doing any MTOW take-offs, so it isnt a big deal. We were just talking about why the four-engined platform and this is one of the major reasons. A two engine platform would suffer from that much thrust loss significantly more than a four engined one would.
Conversely, on the 747SP testbed that the other pictures on on, the rated thrust for the P&W JT9D-7R4 engines that are normally mounted is 56k. Just FYI.
I love good aircraft engineering statistics.
For some, the sky is the limit. For us, it is only the beginning... -- Jack Hunt
Alessandro From , joined Dec 1969, posts, RR: Reply 28, posted (1 year 1 month 6 days 21 hours ago) and read 3973 times:
Quoting 474218 (Reply 23): I seem to remember the RB-211 being test flown on a VC-10, where they removed both port Conways and replaced them with one (1) RB-211. Leaving only the two starboard Conways in case of an emergency.
That´s correct, picture´s are availble in a book about the Tristar.
Russians use the Il-76 (also 4 engined) to test new engines.
Alessandro From , joined Dec 1969, posts, RR: Reply 29, posted (1 year 1 month 6 days 21 hours ago) and read 3952 times:
Quoting PITIngres (Reply 17): There have been various threads on this. Briefly, the issue is that the fan has heretofore been driven on the same shaft as the low-pressure turbine. It turns out that this means that for larger fans, the fan is running faster than optimum (or equivalently, that the LPT is running slower than optimum). By putting a gear drive in, the fan can be made larger and still run at an appropriate speed, without slowing the LPT down. You get increased efficiency since you can run a larger fan and get a larger bypass ratio and still maintain efficiency in the core. The downside is that running all that power thru a gearset is devilish hard to do reliably, and the gearing adds weight.
There are engine guys around who can probably explain it better, but that's how I understand it.
It remind me of another application, the windmill, I know that they had huge problems with the gearboxes to windmills for production of electricity, could you share any technology from the GTF to the windmill industry or opposite?
The PW1000G has been selected as the exclusive engine to power the Mitsubishi Regional Jet (MRJ) and the Bombardier CSeries family, which both enter service in 2013.
Radarbeam From Canada, joined Mar 2002, 1275 posts, RR: 7 Reply 33, posted (1 year 1 month 6 days 20 hours ago) and read 3753 times:
Quoting DocLightning (Reply 24): This engine has never flown before. You have no idea what it's actually going to do.
Actually the engine has flown before. It was previously mounted on PW 747 testbed and has accumulated +300 hours of testing of which 43 hours were flight testing.
Alessandro From , joined Dec 1969, posts, RR: Reply 34, posted (1 year 1 month 6 days 20 hours ago) and read 3706 times:
Quoting 474218 (Reply 31):
Quoting DocLightning (Reply 24):
Yes, but TWO engines. Not one. You wouldn't want to try this same trick with, say, an A330.
But you said:
Quoting DocLightning (Reply 12):
you always want to use a plane with at least 4 engines so that if the test engine fails,
I pointed out that that is not what "always" happens.
Quoting DocLightning (Reply 24):
This engine has never flown before. You have no idea what it's actually going to do.
The RB211 was a new engine that had never been flown before..
Ehh, the VC-10 had 4 engines, but replaced two of them with 1 RB211 engine.
474218 From United States, joined Oct 2005, 3745 posts, RR: 1 Reply 36, posted (1 year 1 month 6 days 19 hours ago) and read 3510 times:
Quoting Radarbeam (Reply 33): Actually the engine has flown before. It was previously mounted on PW 747 testbed and has accumulated +300 hours of testing of which 43 hours were flight testing.
The Rolls Royce RB211 engine made it first flight on the VC-10 test aircraft on 6 March 1970.
Boeing did not even offer a 747 with RB211 engines until 1975.
AA777223 From United States, joined Feb 2006, 809 posts, RR: 9 Reply 37, posted (1 year 1 month 6 days 19 hours ago) and read 3499 times:
Quoting AA777223 (Reply 6): It is an ugly little engine, eh? Kinda ungainly and oddly shaped. It is stranged how is seems to have a band around its mid-section and then the fairing/vane coming out of the back is oddly shaped. Kind of reminds me of the initial RR RB211s that had the vane coming out of the back, a la 742/3 and EARLY 752s.
As much as I think this engine is ugly, after looking at some of these pictures, it seems huge for its application. Think that engine is mounted on a A346, the P&W website has it mounted to a 742. It looks only slight smaller than the JT9 on the 742 and the RR 500 on the A346. Can you imagine that thing strapped under the wing of a A320 or especially 737?! It would be scraping hardcore, haha. I realize it has an exceptionally high bypass ratio, but to only generate 17-23K Lbs of thrust, I wonder if that engine has an exceptionally high weight.
Alessandro From , joined Dec 1969, posts, RR: Reply 38, posted (1 year 1 month 6 days 19 hours ago) and read 3478 times:
Quoting Radarbeam (Reply 33): Actually the engine has flown before. It was previously mounted on PW 747 testbed and has accumulated +300 hours of testing of which 43 hours were flight testing.
Tdscanuck From Canada, joined Jan 2006, 5639 posts, RR: 56 Reply 40, posted (1 year 1 month 6 days 10 hours ago) and read 3008 times:
Quoting Alessandro (Reply 29): It remind me of another application, the windmill, I know that they had huge problems with the gearboxes to windmills for production of electricity, could you share any technology from the GTF to the windmill industry or opposite?
From GTF to windmill, perhaps. The technical challenges of the GTF are much worse (higher power density, smaller form factor, worse operating environment, vicious weight restrictions). Going the other way I'm not so sure...it took PW something like 20 years to get the GTF right.
DocLightning From United States, joined Nov 2005, 7122 posts, RR: 44 Reply 42, posted (1 year 1 month 6 days 4 hours ago) and read 2748 times:
So I had an awful thought. what if one of these gearboxes decided to seize up? So if I understand, the consequence of a planetary gear system is that the outer ring rotates in the opposite direction from the shaft.
So if it seized up, the fan would suddenly stop rotating in its usual direction and do a complete reverse. This would probably destroy the fan at take-off speed, but at cruise with lower RPM's it might just cause the fan to suddenly rotate backwards. Reverse thrust.
And that would be bad. Now, I know that P&W has extensive experience with aircraft gearboxes, given the PT6 and other reduction gearing schemes. So I'm assuming such an event would be unlikely. But it's a scary thought.
Alessandro From , joined Dec 1969, posts, RR: Reply 44, posted (1 year 1 month 5 days 20 hours ago) and read 2305 times:
Quoting Tdscanuck (Reply 40): From GTF to windmill, perhaps. The technical challenges of the GTF are much worse (higher power density, smaller form factor, worse operating environment, vicious weight restrictions). Going the other way I'm not so sure...it took PW something like 20 years to get the GTF right.
Tom.
Yes, but in general the windmills run for longer time than an jetengine. The amount of hours are greater than between service on a jetengine.
PITIngres From United States, joined Dec 2007, 327 posts, RR: 5 Reply 46, posted (1 year 1 month 5 days 20 hours ago) and read 2215 times:
Quoting DocLightning (Reply 42): ...what if one of these gearboxes decided to seize up? So if I understand, the consequence of a planetary gear system is that the outer ring rotates in the opposite direction from the shaft.
So if it seized up, the fan would suddenly stop rotating in its usual direction and do a complete reverse. This would probably destroy the fan at take-off speed, but at cruise with lower RPM's it might just cause the fan to suddenly rotate backwards. Reverse thrust.
I strongly suspect that the gear teeth and/or shafts are fractured into dust immediately after the word "seize". Which decouples the fan from pretty much anything else, and the various parts of the engine can pursue their own failure modes independently.
A342 From Germany, joined Jul 2005, 3828 posts, RR: 1 Reply 47, posted (1 year 1 month 5 days 19 hours ago) and read 2185 times:
Quoting AA777223 (Reply 37): As much as I think this engine is ugly, after looking at some of these pictures, it seems huge for its application. Think that engine is mounted on a A346, the P&W website has it mounted to a 742. It looks only slight smaller than the JT9 on the 742 and the RR 500 on the A346. Can you imagine that thing strapped under the wing of a A320 or especially 737?! It would be scraping hardcore, haha. I realize it has an exceptionally high bypass ratio, but to only generate 17-23K Lbs of thrust, I wonder if that engine has an exceptionally high weight.
The engine that is installed on the A346 is not the production version. It is a demonstrator partly based on the PW6000 and it has 30k lbf thrust.
DocLightning From United States, joined Nov 2005, 7122 posts, RR: 44 Reply 48, posted (1 year 1 month 5 days 15 hours ago) and read 1890 times:
Quoting PITIngres (Reply 46): I strongly suspect that the gear teeth and/or shafts are fractured into dust immediately after the word "seize".
I hadn't thought about that.
Quoting PITIngres (Reply 46): and the various parts of the engine can pursue their own failure modes independently.
you do have a way with words!
My guess is that if this didn't happen, the fan blades would all snap off what with the sudden deceleration from "really fast" to "dead stop". A fan blade on a Trent 800 at 95% power exerts a force on the fan hub that is equivalent to the weight of a locomotive. The forces of a sudden stop would be so enormous that I don't think any known material would be able to hold itself together. So I hope they have a casing that can handle 30 locomotives hitting it from the inside all at once.
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you do have a way with words!
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