Engine upgrades

All about the Pratt & Whitney F135 and the (cancelled) General Electric/Rolls-Royce F136
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quicksilver

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Unread post07 Aug 2019, 11:05

“Sure, just using that speed as a lower threshold to get some feel for endurance time, speed and range before it's throttled-up. I suspect loiter, max-endurance (not necessarily the same V) and max-range cruise speed are all going to be quite close to each other at mid to upper jetstream altitude range.”

How do you define loiter? What is it’s purpose? In other words, if I looked ‘loiter’ up in your flight manual, how would it be different from max endurance?

http://www.eaa1000.av.org/technicl/perf ... tm#Figure_

We’ve talked about this before, but apart from max end and max range everything else is circumstantial. For example, if I was IMC with a wingman (necessarily in parade formation), max end or max range would make formation keeping difficult for that wingy because the jet is so far back on the power that its response to throttle movements lags; not good. So, you’d pick something a little faster that met mission requirements (make your land time...not run out of gas...give yourself some reserves, etc) and put the jet in an rpm range that provided better throttle response.
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element1loop

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Unread post07 Aug 2019, 14:45

quicksilver wrote:How do you define loiter? What is it’s purpose? In other words, if I looked ‘loiter’ up in your flight manual, how would it be different from max endurance?


Best-endurance speed is usually a bit slower than a specified loiter speed, I've always seen that as a result of loiter involving banking in orbits so having more speed margin and performed for a shorter period so a slightly higher flow doesn't matter, it's temporary. While best-endurance is sustained in a straight line so a stability margin is not needed thus lower flow rate and slightly more time up your sleeve.
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weasel1962

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Unread post07 Aug 2019, 23:31

quicksilver wrote:
eloise wrote:1620 nm combat radius is insane, holy sh...t :o


Range...not radius, to wit — “That range improvement applied to the F-35C would add 420nm – taking range for the USN's variant to 1,620nm.”


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sprstdlyscottsmn

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Unread post07 Aug 2019, 23:47

the 600nm radius was also with sub-optimal cruise.
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marauder2048

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Unread post08 Aug 2019, 21:07

quicksilver wrote:How do you define loiter? What is it’s purpose? In other words, if I looked ‘loiter’ up in your flight manual, how would it be different from max endurance?



I've only ever seen it defined as the portion of on-station time flown at the max-endurance fuel flow rate.

And since the on-station average fuel consumption is going to be distorted upwards by the
attack fuel flow requirements, the interplay between those those two fuel flow rates is what typically
guides planners.
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playloud

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Unread post09 Aug 2019, 19:22

quicksilver wrote:
eloise wrote:1620 nm combat radius is insane, holy sh...t :o


Range...not radius, to wit — “That range improvement applied to the F-35C would add 420nm – taking range for the USN's variant to 1,620nm.”

And we know the 1,200 nmi number is already below the spec. It demonstrated a 670 nmi combat radius (A2G), per the SAR. That would make its range at least 1,340 nmi before the upgrade. Internal A2A would be even higher. F-35A is listed at 760 nmi for A2A, giving it a range of 1,520 nmi (before upgrade). The C model should give similar numbers.
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taog

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Unread post18 Sep 2019, 15:03

Pratt Defining Engine Upgrade Package For Block 5 F-35

"...The intent is to deliver options for improving thrust by more than 10-12%, reducing fuel consumption by more than 5-6%, increasing vertical lift by about 2% and increasing overall power and thermal management capacity, Bromberg says. ..."

https://aviationweek.com/defense/pratt- ... ock-5-f-35
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mixelflick

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Unread post19 Sep 2019, 13:03

More thrust for.... expanded super-cruise? Or just more "umph" to accelerate/maneuver. I get the greater range requirement, just wondering what extra thrust will allow it to do vs. what's currently possible?

Requirements were to have F-16 like speed/acceleration and F-18 like nose pointing authority. By all accounts, they've succeeded. But I'd love for it to exceed those F-16/18 specs considerably, and these new engines will hopefully get it there.
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wrightwing

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Unread post19 Sep 2019, 22:32

I think that acceleration, climb rates, take off/bring back weights, range, and loiter, were probably higher priorities, but I'm sure it doesn't hurt the cruise speed in dry thrust (and that's with the conservative 10-12% improvement. There are other claims in the 20+% range, as well.)
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falcon.16

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Unread post19 Sep 2019, 23:20

taog wrote:Pratt Defining Engine Upgrade Package For Block 5 F-35

"...The intent is to deliver options for improving thrust by more than 10-12%, reducing fuel consumption by more than 5-6%, increasing vertical lift by about 2% and increasing overall power and thermal management capacity, Bromberg says. ..."

https://aviationweek.com/defense/pratt- ... ock-5-f-35


Is this option Grown 1.0?
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f119doctor

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Unread post19 Sep 2019, 23:41

Per the AvWeek article, it is Growth option 2, or a variant of it.
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jetblast16

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Unread post20 Sep 2019, 00:42

'There are other claims in the 20+% range, as well'

I'm not doubting you but do you have any links? I saw similar claims about potential engines for the now "Century Series"-styled NGAD, gonad, or whatever the heck they call it these days, in the 50k - 60k thrust class range.
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falcon.16

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Unread post20 Sep 2019, 01:22

f119doctor wrote:Per the AvWeek article, it is Growth option 2, or a variant of it.


Thanks.

I can not read the article, is blocked only for subscribers.
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spazsinbad

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Unread post20 Sep 2019, 01:40

falcon.16 wrote:
f119doctor wrote:Per the AvWeek article, it is Growth option 2, or a variant of it.

Thanks. I can not read the article, is blocked only for subscribers.

The Aviation WEAK article can be viewed by NON-Subscribers who register (such as MOI) - just register for FREE but you will still be a NONsubscriber.
Pratt & Whitney Defining F-35 Engine Upgrade Package
18 Sep 2019 Steve Trimble

"Pratt & Whitney is defining a new engine upgrade option for F-35s delivered starting after 2026, says Matthew Bromberg, president of Military Engines.

The upgrades, the details of which will be defined in about six months, are focused on improvements to the fan and the engine accessories, Bromberg told Aerospace DAILY during a Sept. 17 interview on the sidelines of the Air Force Association’s Air, Space and Cyber Conference.

The intent is to deliver options for improving thrust by more than 10-12%, reducing fuel consumption by more than 5-6%, increasing vertical lift by about 2% and increasing overall power and thermal management capacity, Bromberg says.

Those targets are the proposed baseline improvements advertised for the Growth Option 2.0 upgrade, which remains in discussions for insertion beyond Block 4.2 aircraft delivered starting in 2026, he says.

P&W originally proposed a Growth Option 1.0 upgrade package that offered only thrust and fuel improvements, but no extra capacity for power generation and cooling.

“We found it didn’t resonate because it didn’t have power and thermal management,” Bromberg says.

The Growth Option (GO) and Engine Enhancement Package (EEP) upgrades all stem from technologies developed under the Adaptive Engine Technology Program, which is funded by the Air Force Research Laboratory to design a new engine core.

Pratt & Whitney completed the detailed design review of the XA101 demonstrator engine recently, Bromberg says.

Editor’s Note: The article was corrected to update the timing for EEP and GO 2.0 availability.

Source: https://aviationweek.com/defense/pratt- ... de-package
Last edited by spazsinbad on 20 Sep 2019, 01:43, edited 1 time in total.
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wrightwing

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Unread post20 Sep 2019, 01:42

jetblast16 wrote:'There are other claims in the 20+% range, as well'

I'm not doubting you but do you have any links? I saw similar claims about potential engines for the now "Century Series"-styled NGAD, gonad, or whatever the heck they call it these days, in the 50k - 60k thrust class range.

The ACE/AETP motors were supposed to have a ~20% thrust increase, ~50% improved loiter, and ~30 to 35% range increase.
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