Report comes mere weeks after the shuttering of GE's Adaptive Engine Transition Program (AETP), seemingly owing to whether it would fit in the Navy's & Marine's F-35B & F-35C configurations. Supposedly having an advanced controllable "third airstream" flowing into the engine, this XA100 was supposed to improve range by 30%, thrust by 10%, and "double thermal management capability". https://breakingdefense.com/2023/03/air-force-will-not-devel...
Personally for a plane the US alone expects to purchase well over 2000 of, with ~$80m a plane expected & many significant computer, electronics warfare, & sensor upgrades coming in Block 4 / Technology Refresh-3 (potentially raising price) (https://www.thedrive.com/the-war-zone/new-electronic-warfare...) ... I do wonder if maybe having another really great engine upgrade isn't advantage enough. Hopefully the new Pratt & Whitney is at least good enough. Also noted, the Air Forces Next-Gen Air-Domination (NGAD) might well use adaptive-engine tech.
Notably though, this article is about a defense of the ECU path, which hopefully is indeed sufficient. Also nice, we have many allies who have purchased these planes, and they'll be able to keep a sizable fraction of their existing engines during this upgrade as well.
I don't understand it all but apparently the story is: (a) When the F35 was designed, it reduced the number of external air scoops by using integrated heat exchangers which used the relative cool air from the engine fan (the first stage of the engine) to cool all the plane's systems [1]. Bleed air is when you "bleed" or tap the exhaust of the engine and use it to power other systems i.e., power the system that produces electricity.
The GAO says this design is flawed. To make up for it, pilots have run the engines harder/hotter. Which reduces the life of the engines [2]. The GAO said Lockheed told P&W five years after the program started, it needed more bleed air. Based on our preliminary observations, the PTMS needs more air pressure from the engine to cool subsystems than originally anticipated, which means that the engine is working harder than it was designed to, resulting in reduced engine life. Program officials explained that Pratt & Whitney designed the engine to provide a certain amount of air pressure
to the PTMS, which Lockheed Martin defined early in the development program. While Pratt & Whitney’s F135 engine met those specifications, program officials stated that in 2008, Lockheed Martin discovered that the PTMS would need more air pressure from the engine than originally anticipated to help cool aircraft subsystems. According to program officials, in 2013, Lockheed Martin requested to change the F135’s design to provide more air pressure to the PTMS, but program officials
determined that it was too late to redesign the engine given the cost and schedule impacts of such a change at that stage of the overall program. Program officials decided to continue with the F135 engine’s original
design with the understanding that there would be increased wear and tear on the engine because it would need to provide more air pressure to the PTMS than its design intended. However, the higher air pressure needs results in the engine working harder than intended, which increases maintenance and reduces engine life. As we reported in July 2022, the engine is witnessing higher than expected maintenance
Furthermore, the USAF plans to upgrade the F35 with its new TRS3 computer system to field Block 4 capabilities which will require even more electrical power which will generate even more waste heat etc [3]. TR-3 provides computational horsepower to support Block 4 modernization capabilities. Block 4 upgrades add new and enhanced capabilities to ensure our platform remains relevant against rapidly evolving threats. The existing infrastructure relies on ten-year-old processing and memory, which cannot fully unlock the new capabilities needed for warfighter success. Much like a new mobile cell phone or personal computer, TR-3 will host new
Block 4 capabilities and applications with significantly more computing power and memory than the legacy infrastructure.
Worth observing here that military aircraft having engines with cooling problems and consequent engine life issues is nothing new.
The B-29 that dropped the atom bombs in Japan had engines that were apparently so prone to overheating that rather than prioritising gaining altitude after takeoff B-29 pilots had to prioritise gaining airspeed lest the engines catch on fire. The engines also had an extremely short service life, with engines replaced after as little as 75 hours of service [1]
Similarly, the Soviet MiG-25 was theoretically capable of well over Mach 3, but was limited to Mach 2.8 to prevent the engines overheating [2]
There was a lot of turn-over (no pun intended) in strategic heavy bombers until the B-52. There were also all sorts of medium-heavy and heavy bombers between the B-17 and the B-52.
The MiG-25 had to swap engines after every flight.
Meanwhile, the A-10 is and was an amazing design and yet they want to ditch it.
The F-22, B-1A/B, B-2, KC-46 were previous boondoggles.
And now, ditching the Viper and Hornet for an Jaguar X-type with an unusable motor.
> Meanwhile, the A-10 is and was an amazing design and yet they want to ditch it.
I believe the argument that the A-10 is obsolete is the fact that nowadays the US armed forces have at their disposal far more efficient and safe ways to destroy ground targets and conduct close air support missions.
The design of something is irrelevant if it's obsolete. I'm sure there were exquisite buggy whips back in the day.
Here's an age-old HN post that amusingly enough is a top search hit on Google on this topic:
Long time military aviation fan here, and if I told you this was "normal" not sure anyone would believe me because the word F35 is attached to it. rgmerk already mentioned my favorite example; I was going to specifically mention the Foxbat! It could totally "fly at mach 3" but the engines were going to need a rebuild above mach 2 for operationally significant timeframes and were pretty much trashed above mach ~2.4 (I need a source, I'll get one later).
Famously, or maybe notoriously, the TF30s powering the original F-14 Tomcat were... well a threat unto itself to the aircraft. Tons of speciality parts, out of this world fuel consumption rates, prone to compressor stalls (RIP Goose), and many other problems that lead to their replacement.
I have a secondary theory, and this is a conspiracy theory probably better suited for reddit then HN: There is an intentional, calculated, and widespread disinformation campaign about the F35. Why do I think this? Well 5th generation fighters are probably as good as it's going to get. All technology eventually becomes commodity, and making sure other "near-peer adversaries" aren't in a hurry is probably a good thing. Once quantum radar and energy weapons arrive, the cat is really, really out of the bag. Stalling this deadline far into the future seems like a worthwhile goal.
According to Wikipedia on the MiG-25: "The airspeed indicator was redlined at Mach 2.8, with typical intercept speeds near Mach 2.5 in order to extend the service life of the engines.[28] A MiG-25 was tracked flying over the Sinai Peninsula at Mach 3.2 in the early 1970s, but the flight led to the engines being damaged beyond repair.[34]"
Both citations are for Barron, John. MiG Pilot: The Final Escape of Lt. Belenko. New York: McGraw-Hill, 1980. ISBN 0-380-53868-7.
Most of us years ago pointed out the F-35 was heavy and not very aerodynamic. Meaning that the single engine would be burdened hauling that thing around. It's actually worse than we thought! If the engineers can somehow squeeze out 35% more thrust then the plane will be performant. I see that as being difficult.
This sort of waste is a feature not a bug. More problems, more money.
I'm just finishing reading a book [0] about the horrible waste and the cushy relationships built into giant weapon systems in the US Air Force in the 60s-70s, especially the C5-A Galaxy, and this sounds familiar. I've also been following Project on Government Oversight[1] when they look at the has been keeping track of the F-35 mess(among others).
Contracts are written so that when the contractor can't live up the contract for how a thing should perform, the taxpayer picks up the tab to fix it, or the contract is re-written so that however the thing - missile/plane/widget performs is the new baseline. The threat of actually enforcing a contract is rarely attempted, because there is no motivation to do so.
For the F-35 (as with the C-141, C5-A, B1-B, F22, .) production is being done concurrently with testing. There have been almost 900 F-35s built, and a decision for 'full rate production' hasn't been made, and likely won't be until 2024[2], So all the planes produced before the problems found during testing have to refitted.
[0] "The High Priests of Waste" by A. Ernest Fitzgerald, one of Nixon's Enemies, for telling the truth to congress.
From the book TL;DR:
Refusing to look at what it should cost to build a part, terribly inefficient, mismanaged factories (lots of idle machines/personnel), terrible management/cost administration vs. what a normal commercial industry company would do. Covering up/glossing over major technical and financial overruns by Air-force, Defence Department Civilians and 'defence' contractors, all sort of in concert.
"The original program engine specification allocated 15 kW of bleed air extraction to support system cooling requirements, and the F135 engine was designed, tested, and qualified to this specification with a level of margin available for future growth," Schmidt wrote. "During the final stages of initial aircraft development, air vehicle cooling requirements grew to exceed planned bleed air extraction."
"To provide the necessary bleed air, the engine is required to run hotter, and the program is realizing the effects of this through an increase in operating temperature, and a decrease in engine life, which is driving earlier depot inductions and an increase in lifecycle cost"
The F135 engine in the F-35 was derived from the F119 engine powering the F-22 (dating back to the 80's). The original plan was to develop a new F136 engine specifically for this plane, but it got slashed as a cost-cutting measure late in development.
16 comments
[ 3.5 ms ] story [ 40.7 ms ] threadPratt came up with their own adaptive XA101, in case. But primarily has been pushing a Engine Core Upgrade (nee Engine Enhancement) plan and new Emergency Power and Cooling System, which is now locked in, which leaves most of the existing F135 engine intact. It too claims double the cooling capability, with 7% range & thrust boost. https://www.defensenews.com/air/2023/03/13/pentagon-rethinks... https://aviationweek.com/defense-space/aircraft-propulsion/c...
Personally for a plane the US alone expects to purchase well over 2000 of, with ~$80m a plane expected & many significant computer, electronics warfare, & sensor upgrades coming in Block 4 / Technology Refresh-3 (potentially raising price) (https://www.thedrive.com/the-war-zone/new-electronic-warfare...) ... I do wonder if maybe having another really great engine upgrade isn't advantage enough. Hopefully the new Pratt & Whitney is at least good enough. Also noted, the Air Forces Next-Gen Air-Domination (NGAD) might well use adaptive-engine tech.
Notably though, this article is about a defense of the ECU path, which hopefully is indeed sufficient. Also nice, we have many allies who have purchased these planes, and they'll be able to keep a sizable fraction of their existing engines during this upgrade as well.
The GAO says this design is flawed. To make up for it, pilots have run the engines harder/hotter. Which reduces the life of the engines [2]. The GAO said Lockheed told P&W five years after the program started, it needed more bleed air. Based on our preliminary observations, the PTMS needs more air pressure from the engine to cool subsystems than originally anticipated, which means that the engine is working harder than it was designed to, resulting in reduced engine life. Program officials explained that Pratt & Whitney designed the engine to provide a certain amount of air pressure to the PTMS, which Lockheed Martin defined early in the development program. While Pratt & Whitney’s F135 engine met those specifications, program officials stated that in 2008, Lockheed Martin discovered that the PTMS would need more air pressure from the engine than originally anticipated to help cool aircraft subsystems. According to program officials, in 2013, Lockheed Martin requested to change the F135’s design to provide more air pressure to the PTMS, but program officials determined that it was too late to redesign the engine given the cost and schedule impacts of such a change at that stage of the overall program. Program officials decided to continue with the F135 engine’s original design with the understanding that there would be increased wear and tear on the engine because it would need to provide more air pressure to the PTMS than its design intended. However, the higher air pressure needs results in the engine working harder than intended, which increases maintenance and reduces engine life. As we reported in July 2022, the engine is witnessing higher than expected maintenance
Furthermore, the USAF plans to upgrade the F35 with its new TRS3 computer system to field Block 4 capabilities which will require even more electrical power which will generate even more waste heat etc [3]. TR-3 provides computational horsepower to support Block 4 modernization capabilities. Block 4 upgrades add new and enhanced capabilities to ensure our platform remains relevant against rapidly evolving threats. The existing infrastructure relies on ten-year-old processing and memory, which cannot fully unlock the new capabilities needed for warfighter success. Much like a new mobile cell phone or personal computer, TR-3 will host new Block 4 capabilities and applications with significantly more computing power and memory than the legacy infrastructure.
[1] https://www.codeonemagazine.com/article.html?item_id=28 [2] https://armedservices.house.gov/sites/republicans.armedservi... [3] https://armedservices.house.gov/sites/republicans.armedservi...
The B-29 that dropped the atom bombs in Japan had engines that were apparently so prone to overheating that rather than prioritising gaining altitude after takeoff B-29 pilots had to prioritise gaining airspeed lest the engines catch on fire. The engines also had an extremely short service life, with engines replaced after as little as 75 hours of service [1]
Similarly, the Soviet MiG-25 was theoretically capable of well over Mach 3, but was limited to Mach 2.8 to prevent the engines overheating [2]
[1] https://en.wikipedia.org/wiki/Boeing_B-29_Superfortress
[2] https://en.wikipedia.org/wiki/Mikoyan-Gurevich_MiG-25
The MiG-25 had to swap engines after every flight.
Meanwhile, the A-10 is and was an amazing design and yet they want to ditch it.
The F-22, B-1A/B, B-2, KC-46 were previous boondoggles.
And now, ditching the Viper and Hornet for an Jaguar X-type with an unusable motor.
MIC loves it: more problems = more $$$
I believe the argument that the A-10 is obsolete is the fact that nowadays the US armed forces have at their disposal far more efficient and safe ways to destroy ground targets and conduct close air support missions.
The design of something is irrelevant if it's obsolete. I'm sure there were exquisite buggy whips back in the day.
Here's an age-old HN post that amusingly enough is a top search hit on Google on this topic:
https://news.ycombinator.com/item?id=11031662
Only when it was pushed to the edge of its operating limits, if I understand correctly?
Famously, or maybe notoriously, the TF30s powering the original F-14 Tomcat were... well a threat unto itself to the aircraft. Tons of speciality parts, out of this world fuel consumption rates, prone to compressor stalls (RIP Goose), and many other problems that lead to their replacement.
I have a secondary theory, and this is a conspiracy theory probably better suited for reddit then HN: There is an intentional, calculated, and widespread disinformation campaign about the F35. Why do I think this? Well 5th generation fighters are probably as good as it's going to get. All technology eventually becomes commodity, and making sure other "near-peer adversaries" aren't in a hurry is probably a good thing. Once quantum radar and energy weapons arrive, the cat is really, really out of the bag. Stalling this deadline far into the future seems like a worthwhile goal.
Both citations are for Barron, John. MiG Pilot: The Final Escape of Lt. Belenko. New York: McGraw-Hill, 1980. ISBN 0-380-53868-7.
https://en.wikipedia.org/wiki/Mikoyan-Gurevich_MiG-25#cite_n...
I'm just finishing reading a book [0] about the horrible waste and the cushy relationships built into giant weapon systems in the US Air Force in the 60s-70s, especially the C5-A Galaxy, and this sounds familiar. I've also been following Project on Government Oversight[1] when they look at the has been keeping track of the F-35 mess(among others).
Contracts are written so that when the contractor can't live up the contract for how a thing should perform, the taxpayer picks up the tab to fix it, or the contract is re-written so that however the thing - missile/plane/widget performs is the new baseline. The threat of actually enforcing a contract is rarely attempted, because there is no motivation to do so.
For the F-35 (as with the C-141, C5-A, B1-B, F22, .) production is being done concurrently with testing. There have been almost 900 F-35s built, and a decision for 'full rate production' hasn't been made, and likely won't be until 2024[2], So all the planes produced before the problems found during testing have to refitted.
[0] "The High Priests of Waste" by A. Ernest Fitzgerald, one of Nixon's Enemies, for telling the truth to congress.
From the book TL;DR: Refusing to look at what it should cost to build a part, terribly inefficient, mismanaged factories (lots of idle machines/personnel), terrible management/cost administration vs. what a normal commercial industry company would do. Covering up/glossing over major technical and financial overruns by Air-force, Defence Department Civilians and 'defence' contractors, all sort of in concert.
[1] pogo.org [2] https://www.defensenews.com/air/2023/01/24/dod-delays-key-f-...
"To provide the necessary bleed air, the engine is required to run hotter, and the program is realizing the effects of this through an increase in operating temperature, and a decrease in engine life, which is driving earlier depot inductions and an increase in lifecycle cost"
The F135 engine in the F-35 was derived from the F119 engine powering the F-22 (dating back to the 80's). The original plan was to develop a new F136 engine specifically for this plane, but it got slashed as a cost-cutting measure late in development.