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Airbus A319 IAE Vs. Engines  
User currently offlinedla320 From United States of America, joined Aug 2011, 22 posts, RR: 0
Posted (2 years 5 months 1 week 2 days 23 hours ago) and read 5502 times:

Why do some airlines choose one over the other? Does one have a climb rate, or range? Can you tell the diffrence when flying?

7 replies: All unread, jump to last
 
User currently offlineNorthwest727 From United States of America, joined Jul 2005, 491 posts, RR: 1
Reply 1, posted (2 years 5 months 1 week 2 days 22 hours ago) and read 5480 times:

It all depends on what is more important to the airlines that will utilize the engine, factors such as maintenance, power (which in turn affects the aircraft's useful load, and/or performance like shorter t/o runs), fuel burn, and of course, who will give the best deal. Each engine has its pros and cons, and that is why we see IAE V2500 and CFM-56 engines for the A319. On the other hand, the GE CF6-32 for the 757 had no takers, thus GE dropped out of the offerings for the 757.

I'm sure an expert can chime in on more advantages and disadvantages, but one of such points that I am aware of: IAE engines are more anemic with fuel, but have an appetite for oil.


User currently offlineKELPkid From United States of America, joined Nov 2005, 6265 posts, RR: 3
Reply 2, posted (2 years 5 months 1 week 2 days 14 hours ago) and read 5333 times:

The IAE is an outstanding hot and high engine, IIRC (hence operators like HP and UA using it). The CFM has slightly higher TSFC, but slightly better emissions (go figure. Pratt builds the core in the V2500. Remember the J57  ). Also, if you already have a lot of CFM56's in the fleet (737's, maybe A340's) it kind of makes sense to stay "in the family" on your engines (even if there's zero spares parts commonality between different versions of the CFM56, which I don't know if that is the case or not).


Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlinePihero From France, joined Jan 2005, 4163 posts, RR: 76
Reply 3, posted (2 years 5 months 1 week 2 days 13 hours ago) and read 5301 times:
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The engines are very closely matched in terms of performance but I personally have a preference for the CFM.
It is easier to use ( the main difference and a dead giveaway when you enter a cockpit is that the V2500 uses EPR as its main parameter, and I for one had rather use N1, like on the CFM-56).
It is also surprising to know that the -56 is a lot more automated : the start sequence is wayyyyy more advanced on the -56 although it is the older engine. The 2500 takes about a minute to start up to the 30 seconds or so for the CFM.
That's from an operator's point of view.
I really don't know about the economics of both engines.



Contrail designer
User currently offlineferpe From France, joined Nov 2010, 2792 posts, RR: 59
Reply 4, posted (2 years 5 months 1 week 20 hours ago) and read 5000 times:

@Pihero or others who know:

What would be the typical TO and cruise settings for the V2500 and CFM56 engines? I know you derate for the most part for take-off, could you give the typical values for the max take-off and a "day-at-office" take-off. In military engines I have flown we went over 100% N1 for some reason, do you also do that on civil engines? I am most interested in the cruise N1 vs thrust relationship, the cruise thrust is a fraction (typical 1/7 of TO thrust) but the N1 would stay in the region of 70-80% IMO (I have a good idea of the thrust in lbf or N but not the corresponding N1).

Also how do you show the EPR values, as % or pressure? What would be typical values for TO and Cruise?



Non French in France
User currently offlineimiakhtar From , joined Dec 1969, posts, RR:
Reply 5, posted (2 years 5 months 1 week 10 hours ago) and read 4892 times:

Quoting ferpe (Reply 4):
@Pihero or others who know:

What would be the typical TO and cruise settings for the V2500 and CFM56 engines? I know you derate for the most part for take-off, could you give the typical values for the max take-off and a "day-at-office" take-off. In military engines I have flown we went over 100% N1 for some reason, do you also do that on civil engines? I am most interested in the cruise N1 vs thrust relationship, the cruise thrust is a fraction (typical 1/7 of TO thrust) but the N1 would stay in the region of 70-80% IMO (I have a good idea of the thrust in lbf or N but not the corresponding N1).

Also how do you show the EPR values, as % or pressure? What would be typical values for TO and Cruise?

These cruise videos should get you started. First two videos are IAE at cruise, last one is cfm:

http://www.youtube.com/watch?v=ajVNGhN8k58

http://www.youtube.com/watch?v=LlDUqWKt42M&feature=related

http://vimeo.com/23414415


User currently offlinemandala499 From Indonesia, joined Aug 2001, 6590 posts, RR: 75
Reply 6, posted (2 years 5 months 1 week 7 hours ago) and read 4861 times:

Quoting dla320 (Thread starter):
Why do some airlines choose one over the other?

On a per hour basis...
If you want cheaper fuel burn, go with IAE V2500-A5...
If you want cheaper maintenance, go with CFM56-5B...
If you want to lose out on both in today's competitive environment... use either of the V2500-A1 or CFM56-5A

Comparing 2 A320 operators with similar operating environments, the IAE V2500-A5 were more reliable, but expensive to maintain... so one must balance the trade off carefully.

And yes, the CFMs are sold cheaper than the V2500s. That also a factor...

Quoting Northwest727 (Reply 1):
IAE engines are more anemic with fuel, but have an appetite for oil.

V2500-A1s are are jokingly "guzzles more oil than fuel"...   

Quoting dla320 (Thread starter):
Can you tell the diffrence when flying?

I'll add to Pihero...
Apart from the N1 vs EPR gauges... outside the take off and landing phases, you won't notice much.
The V2500s have a much bigger bite on the reversers than the CFM56.
Climb rates are about the same.

Quoting ferpe (Reply 4):
Also how do you show the EPR values, as % or pressure?

Simply pressure ratio... number goes from 1.00 to whatever... Any number bigger than 1 simply means the exhaust pressure is bigger than the inlet pressure... ie: it is pushing itself forward. (and numbers less than 1, we used to get them on 732s, means the engine is dragging itself!    )

Quoting ferpe (Reply 4):
What would be the typical TO and cruise settings for the V2500 and CFM56 engines? I know you derate for the most part for take-off, could you give the typical values for the max take-off and a "day-at-office" take-off. In military engines I have flown we went over 100% N1 for some reason, do you also do that on civil engines? I am most interested in the cruise N1 vs thrust relationship, the cruise thrust is a fraction (typical 1/7 of TO thrust) but the N1 would stay in the region of 70-80% IMO (I have a good idea of the thrust in lbf or N but not the corresponding N1).

The 320 family engines are basically "identical" to the 321 engines, for 33,000lbs take off thrust... The N1 value however, isn't always limited to 100%, it's just an arbitrary number from 0% = 0 RPM to x% = X RPM. However, the x-X conversion is the same for all CFM56-5B family... -5A family has a different set of "conversion", and the V2500-A1 and -A5 each have their own different "conversion" numbers...

This is probably why some prefer EPRs... coz it's simpler (see above), and relationship between EPR and thrust is linear... and the complexities are in altitude and temperature... (although the old JT8D on the 732 have damn easy rule of thumb to remember for consistent performance) and does not reflect "strain on the spools")... regardless on what engine you got...

N1 relationship to thrust, is non-linear... varying altitudes and temperatures can throw havoc into engine limitations during climb, but the "strain on the spools" are directly correlated with the N1).

A319? Over here, things normally we go at sea level and 30C... ish... over here    From the manuals:
Non derate/Flex numbers:
CFM 86-87% on 319s, 92-93% on 320s (96-97% for the older CFM56-5As)... >100% on the 321s... (they're all the same engine, just different FADEC imposed limits to match the required thrust for the aircraft).

Cruise would be about 77.5-85% depending on conditions of course...

On IAE (-A5s)
319s EPR 1.393 - 1.405 (or 86-87% N1), 1.397-1.413s (or 89-91% N1)for 320s...
Max cruise woud be about 1.35 - 1.42 or something like that... and N1s would be about 79-82% ish... on the 319-320 with IAEs...

Don't take the above as gospel... they're just simplistic explanations!

Mandala499



When losing situational awareness, pray Cumulus Granitus isn't nearby !
User currently offlineferpe From France, joined Nov 2010, 2792 posts, RR: 59
Reply 7, posted (2 years 5 months 1 week 6 hours ago) and read 4846 times:

Thanks both for great answers    , now I have a much better idea.

The relationship N1 to thrust is truly non linear, easier to grasp but EPR tells you a more true story. Nice to know that the Civies also go beyond 100% sometimes    it's aviation after all....  Wow!     .



Non French in France
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