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Revelation
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AvWeek: USAF issuing 2x$1B Contracts for 6th Gen Fighter Engine 'War'

Fri Jun 24, 2016 4:34 pm

AvWeek has posted http://aviationweek.com/defense/three-stream-engine-moves-new-phase. I'm a subscriber, not sure if you can get it via free registration or not.

It points out how GE and PW are basically getting $1B contracts to develop 'adpative cycle technology' engines for 6th gen fighters AND potential re-enginging of the F-35, which means it should lead to a feeding frenzy, with Pratt having the most to lose since it's the incumbent on F22, F35 and even B21.

The goal is to mature 'three stream technology' using an engine in the 45,000 pound category that will be available in the mid 2020s and will fit in the F35 engine bay but can be used in other roles too.

Adaptive engines can dynamically change the fan's pressure ratio and/or the overall bypass ratio depending on need. A multi stage fan is used to change its pressure ratio. The 'third stream' is outside of the standard core and bypass flows and its use alters the bypass ratio.

It's interesting that GE and Pratt both have designs to do similar things. PW seems to be counting on its experience and incumbency. As usual GE is relying on its materials (CMCs) and aerodynamics strengths to build a super efficent high temp and high pressure core. Since it's on the outside looking in I think they will be pretty aggressive.
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Ozair
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Re: AvWeek: USAF issuing 2x$1B Contracts for 6th Gen Fighter Engine 'War'

Fri Jun 24, 2016 11:59 pm

Revelation wrote:
AvWeek has posted http://aviationweek.com/defense/three-stream-engine-moves-new-phase. I'm a subscriber, not sure if you can get it via free registration or not.

It points out how GE and PW are basically getting $1B contracts to develop 'adpative cycle technology' engines for 6th gen fighters AND potential re-enginging of the F-35, which means it should lead to a feeding frenzy, with Pratt having the most to lose since it's the incumbent on F22, F35 and even B21.

The goal is to mature 'three stream technology' using an engine in the 45,000 pound category that will be available in the mid 2020s and will fit in the F35 engine bay but can be used in other roles too.

Adaptive engines can dynamically change the fan's pressure ratio and/or the overall bypass ratio depending on need. A multi stage fan is used to change its pressure ratio. The 'third stream' is outside of the standard core and bypass flows and its use alters the bypass ratio.

It's interesting that GE and Pratt both have designs to do similar things. PW seems to be counting on its experience and incumbency. As usual GE is relying on its materials (CMCs) and aerodynamics strengths to build a super efficent high temp and high pressure core. Since it's on the outside looking in I think they will be pretty aggressive.


This continues the money spent over the last 5 years or so maturing this technology. We have had a couple of threads on this previously including this one I posted last year. viewtopic.php?t=1027861

From what I understand, unless some design changes are made to the internals of the F-35, it won't be able to make full use of a third stream. PW are already working on a 5-7% thrust increase and 10% fuel burn reduction for the F135 from technologies funded by AETD/ADVENT. Perhaps a enhanced F-35D in 2030 will have the internal changes required to use a third stream, among other enhancements.
 
Legs
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Re: AvWeek: USAF issuing 2x$1B Contracts for 6th Gen Fighter Engine 'War'

Sat Jun 25, 2016 1:11 am

Ozair wrote:
will have the internal changes required to use a third stream, among other enhancements.


Are structural changes to the engine bay required, or is it just other sub-systems?
 
Ozair
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Re: AvWeek: USAF issuing 2x$1B Contracts for 6th Gen Fighter Engine 'War'

Sat Jun 25, 2016 2:19 am

Legs wrote:
Ozair wrote:
will have the internal changes required to use a third stream, among other enhancements.


Are structural changes to the engine bay required, or is it just other sub-systems?

I don't think so. The image below shows the location of the current fuel tanks.
Image\

And here how low the weapons sit in relation to the fuselage,
Image

so I think the internal changes will probably be to the fuel tanks that sit along and around the intake ducting. If you consider that ADVENT is supposed to bring a 25% reduction in fuel burn then the F-35 can sacrifice some of the already high ratio of fuel it carries to gain that efficiency.

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