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How Efficient Would A 737RE Be With Same Fan Size?

Posted: Sun Apr 17, 2011 11:47 am
by morrisond
How much more efficient would the 737 be by literally slapping new engines on using existing hookups and no other changes to the frame? I call this the 737AEO (Alternative Engine Option)

I've read that fan diameter does not mean as much below a certain distance - is this 500nm, 1000nm or 1500nm where what 90% of NB operations take place?

What percentage of efficiency gain would you get by going this route? 75% of what you would get be resizing and optimizing?

Please correct my assumptions below if I am wrong. But in this scenario I'm assuming that Boeings involvement in this would be very limited, it would almost be like the aftermarket re-engining an out of production airframe, with time and cost being born by the engine manufacturers. It would be like Boeing going to Pratt and saying yes you can offer a new power plant for our frame, but we aren't changing anything, you design the new nacelle as well.

Assumptions

- A new generation engine at approximately same fan diameter would not be any heavier, so that you do not have to change the gear or wing to support it. I've read that the newer engines are heavier but is that because they have bigger fans?

- The new engine could use the existing hookups for the current engine, making the New engine backwards compatible with older 737NG's, increasing the appeal of a new engine program to an engine manufacturer as you would have the ability to re-engine older planes

- The only other improvements to the frame are the normal ones being made to the frame in the course of time anyways

- This frees up Boeing to do a bigger 797

Please discuss. Personally I think this is the route Boeing should go. If they can stay within a few percent for absolutely minimal cost they can then go and change the game by building a twin aisle 2x3x2 797 that is optimised for the 1500-4500nm mission and 180-250 (1 class) market.

RE: How Efficient Would A 737RE Be With Same Fan Size?

Posted: Sun Apr 17, 2011 12:09 pm
by par13del
The latest generation 737's already have the largest fan that they can get without Boeing's involvement, note that the nacelle is "cut off" at the bottom, that was the compromise Boeing made to not increase the ground clearance height of the a/c, so no go on the premise that the engine makers can assume all the risk and work for a new engine with larger fan.
Now if they were to make a more efficient engine with the same fan size that they could do without Boeing.

RE: How Efficient Would A 737RE Be With Same Fan Size?

Posted: Sun Apr 17, 2011 12:13 pm
by AirNZ
What is a 737RE in the first place?

RE: How Efficient Would A 737RE Be With Same Fan Size?

Posted: Sun Apr 17, 2011 12:48 pm
by morrisond
Quoting AirNZ (Reply 2):
What is a 737RE in the first place?

Sorry 737NEO I was trying to signify a difference between what Airbus is doing with the 320 and what would need to be done under a pure re-engining scenario

RE: How Efficient Would A 737RE Be With Same Fan Size?

Posted: Sun Apr 17, 2011 11:12 pm
by prebennorholm
Quoting morrisond (Thread starter):
A new generation engine at approximately same fan diameter would not be any heavier...

Talking about the Pratt GTF, then this is false. The gear box alone will add substantial new weight.

Quoting morrisond (Thread starter):
I've read that fan diameter does not mean as much below a certain distance - is this 500nm, 1000nm or 1500nm where what 90% of NB operations take place?

Sticking with the 61 inch fan diameter, Boeing will be very hard pressed competing with other modern planes on noise levels. If a 737NEO risks to be banned from night ops, evening ops, or all day ops on 10% or 50% of airports in 2025 or 2030 - airports where coming Embraers, CSeries, Superjets and Airbuses operate in and out all day long - then it is a non-starter.