USAF/US NAVY 6th Generation Fighter Programs - F/A-XX, F-X, NGAD, PCA, ASFS news

LMFS said:
Yeah, that is exactly what I mean. Since the engine diameter is not going to change a lot, BPR may be increased compared to F135, but will it be by a big margin? Odds are that it is not going to be turned into a high bypass engine, and 30% reduction in consumption is a lot compared to an engine that is very modern and efficient already, and has been designed for subsonic flight
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Say the BPR is exactly the same, but you can increase exhaust velocity by sending everything through the core like a turbojet. Will you see a 30% reduction in consumption? Maybe. It won't be in the subsonic regime.
The increased efficiency will be at the higher airspeeds where you are now getting more thrust for less fuel burn. Maybe that let's you supercruise. Maybe that just substantially increases the airspeed you can cruise with a tolerable fuel burn, but it's not hard to see how that could translate to more speed, range, and operational possibilities for the F-35 in either case.
 
_Del_ said:
I wasn't making an "argument".

He seemed confused that there were varying figures for the TFSC.

for the F135's TSFC there's competing numbers...
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He followed with numbers he didn't "trust".

I just tried to explain that there is no absolute figure. The TFSC will depend on the circumstances. None of the numbers he quoted from various sources need to be "wrong" or not trusted. They can all be true for some given set of variables. High, medium, low altitude, military power, cruise setting, best endurance speed, best cruise speed, etc will all result in a different TFSC.
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At the time those articles had been published no F135 had actually flown in the air (the X-35s used F119 variants that, while they would've been similar, were still several years of development away from being refined into the F135), so unless the source had referencing calculated / simulated performance figures for different flight regimes they would've been sea level test-stand figures (which as far as I'm aware the vast majority of engine performance brochure figures come from anyway).

Also the numbers that I didn't trust from the 0.7lb/lbf/hr figure website were things like claims that the F135 has a 0.2 bypass ratio, which is definitely incorrect; P&W have officially published numbers of 0.57 for the CTOL/CV engines and 0.56->0.51 for conventional and STOVL mode (not counting the lift-fan as bypass). The F119-PW-611 used on the X-35 might have been notably different, but it must've retained relatively similar BPR, etc figures to today's F135 to make the lift-fan work and fit the (roughly) same engine bay dimensions on the X-35.

LMFS said:
25% less consumption, 35% more range, 50% more persistence... it reads definitely like sales pitch / best case figures to me. They don't indicate what engine they are taking as reference, it may be F135 as you say but until now I have seen no proof, I will look further.

They also mention 60% more heat transference, in fact I seem to remember reading in an official document that the adaptive engines were critical to remove current restrictions regarding usable fuel and its temperature from the F-35. It may have an impact in those numbers, if for instance the fuel consumption is reduced a 25% plus due to better heat sink properties the engine allows to reduce the amount of non-usable fuel on board, they may in some circumstances reach that 35% extra range they announce. And of course, at high speeds it may not be possible to bypass so much air so that the heat sink function would not operate as effectively in that regime... it is a complex technology
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You're right that they don't explicitly name the F135 as the baseline that they're referencing, but I'm skeptical that it'd be any other engine (*maybe* it could be their F136) considering that the engines are meant to fit the F-35.
 
Sundog said:
jsport said:

New US Air Force chief of staff forecasts aircraft platform cuts

The US Air Force (USAF) is likely to make major aircraft platform cuts in the next couple of years as it reorganises for near-peer competition against nations such as...
link.defensenews.com
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i.e. - The USAF, after decades of trying, thinks they have finally found a way to get rid of the A-10.
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You could say that about the B-1 now as that seems to have a lot of issues.
 
My problem is, after reading the document, I have no idea what he is advocating. It's a puff piece. There isn't any concrete action listed in the document and most of what he is talking about with regard to "integration" and "networking", etc., has been going on for years. It's a full on Powerpoint Warrior document. Get back to me when he has something substantive.
 
IMO the target are all the C-135 based airframe: AWACS, JSTAR, RC, KC... They all could have to go.
 
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At some point in the article, it is mentioned it is a "virtual version"... Is it just simulation or a "true" plane?
 
oluen said:
At some point in the article, it is mentioned it is a "virtual version"... Is it just simulation or a "true" plane?
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Yeah, I'll be surprised if there isn't some marketing stretching of the truth there. "Already successfully flown" in the simulator maybe.
 
Just my view, but I don't think this is stretching the truth at all. Anyone who knows Roper knows that isn't his style. In 2016, the Government gave GE and Pratt $1B contracts for a new fighter engine. It seems unlikely to me that they would award engine contracts without a near simulteneous airframe contract. Also, the funding for the 6th generation aircraft jumped significantly in FY19 and FY20. Adding it up, it seems likely they would be flying a demonstrator now. I'd sure like to know what records they broke with the vehicle.
 
Wasn't this flown as part of that DARPA program started in 2015 or 2016?
 
I don't know and You may be correct. But I would think that if you were correct, it would be a different vehicle. If the engine contracts were issued to Pratt and GE in 2016, it's just my view, but I doubt that funding level is sufficient to pay for engines plus flight test.
 
I recall the reports 2 years ago about a small demonstrator of the SR-72 being spotted. This would probably be the new fighter instead.
 
sublight is back said:
“We’ve already built and flown a full-scale flight demonstrator in the real world, and we broke records in doing it”
If this is true, then they are certainly in "not fucking around" mode.
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I will believe it when I see it. As far as we know they haven't even started on the engines. (3-stream follow-on to the F135 drop-in replacement.)
 
sferrin said:
sublight is back said:
“We’ve already built and flown a full-scale flight demonstrator in the real world, and we broke records in doing it”
If this is true, then they are certainly in "not fucking around" mode.
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I will believe it when I see it. As far as we know they haven't even started on the engines. (3-stream follow-on to the F135 drop-in replacement.)
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Havent they had ADVENT and follow-ons since 2012?
 
sferrin said:
sublight is back said:
“We’ve already built and flown a full-scale flight demonstrator in the real world, and we broke records in doing it”
If this is true, then they are certainly in "not fucking around" mode.
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As far as we know they haven't even started on the engines. (3-stream follow-on to the F135 drop-in replacement.)
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Testing for one such engine(albeit demonstrator) was completed back in 2017
www.flightglobal.com

P&W completes testing on F135 engine with adaptive fan

Tests this year on an F135 core engine paired with an experimental fan module featuring adaptive bypass airflow to improve fuel efficient and cooling capacity "met or exceeded expectations", says engine manufacturer Pratt & Whitney.
www.flightglobal.com www.flightglobal.com

Money has been pouring in for the last 5 years.
www.flightglobal.com

Adaptive cycle engine enters final phase of development

The US Air Force has awarded a $1 billion contract to GE Aviation to continue development of a next-generation military jet engine and prepare for an anticipated competition in the early 2020s against Pratt & Whitney for the chance to power a new combat aircraft and possibly ...
www.flightglobal.com www.flightglobal.com

www.aviationtoday.com

GE's Adaptive Fighter Engine Design Complete

GE Aviation has completed the detailed design process of its XA100 engine under the U.S. Air Force's Adaptive Engine Transition Program (AETP).
www.aviationtoday.com www.aviationtoday.com
 
If they created a demonstrator that has already flown, I think we can assume it was unmanned.
 
I think the SR-72 was a concept entirely invented by LMT - just as BA had invented their hypersonic concept. Speaking with LMT, the SR-72 was not a concept that reflected an actual program. I'm just guessing, but you may be referring to the aircraft observed inflight over Texas? If so, I think those were subsonic and I don't know if those aircraft were actually identified. Also, I think the SR-72 designation follows the SR-71 which followed the XB-70 - designations given to strategic aircraft. Since that time, we've had the B-1, B-2, and now B-21. So even if there were a strategic hypersonic concept, I don't think (just my view) that it would be given the designation SR-72.
 
sferrin said:
Read somewhere of a Martin Baker design (MB-5 maybe?) had its exhaust pipes oriented such that they produced forward thrust. (Maybe everybody did that.) Got hot air, may as well use it.
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This was a common solution I believe.

A better WWII analogy for what is being done here with rejecting waste heat to the bypass stream for net propulsive gain would be the Meredith Effect (but no longer relying on ram compression before heat addition thanks to the fan upstream).

Even the transfer of this established concept to the turbofan engine isn't entirely original though, quite a few Soviet/Russian engines (NK-25/32, D30-F6, AL-31F family) have a large HPC bleed air heat exchanger in the fan duct to lower HPT NGV cooling air temperature. Granted, the engine is not used as a heat sink for other systems here, but the basic mechanism is the same (and I believe the F135 PTMS/IPP actually handles waste heat from other sources already).

I believe a similar solution (that is to say, for turbine cooling) is among the "innovations" introduced in the latest GE airliner turbofans.
 
dark sidius said:
With the Billions of black programs it won't be difficult to build demonstrators in secrecy.
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Thing is is I believe most black funding is spread out over many much more mundane programs. In any case I'm stoked to hear that we have at least some hardware in testing and its currently black. Granted we have no idea how actually sophisticated it is and could be nothing but a simple airframe. I've been skeptical (and remain so) of the digital century series but I'm starting to warm to it.
 
sferrin said:
sublight is back said:
“We’ve already built and flown a full-scale flight demonstrator in the real world, and we broke records in doing it”
If this is true, then they are certainly in "not fucking around" mode.
Click to expand...
I will believe it when I see it. As far as we know they haven't even started on the engines. (3-stream follow-on to the F135 drop-in replacement.)
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Roper is slightly prone to overstatement; he really oversold the maturity of CD ATACMS for example.

And the claims about O&S savings are strange; basically you fly NGAD for no more than 200 hours a year
and throw it away after 16 years or before what would be like the second PDM for a current fighter.
 
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marauder2048 said:
sferrin said:
sublight is back said:
“We’ve already built and flown a full-scale flight demonstrator in the real world, and we broke records in doing it”
If this is true, then they are certainly in "not fucking around" mode.
Click to expand...
I will believe it when I see it. As far as we know they haven't even started on the engines. (3-stream follow-on to the F135 drop-in replacement.)
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Roper is slightly prone to overstatement; he really oversold the maturity of CD ATACMS.
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You wouldn't think that one would even be difficult. Slap a Harpoon seeker on ATACMs and call it good. (Yes, I know it;s more complicated than that, but all your lego pieces already exist.)

1600211525153.png

(Yes, I know stuffing everything in there would be a challenge, and might need rearranging, but it was a quick and dirty fit.)
 
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sferrin said:
marauder2048 said:
sferrin said:
sublight is back said:
“We’ve already built and flown a full-scale flight demonstrator in the real world, and we broke records in doing it”
If this is true, then they are certainly in "not fucking around" mode.
Click to expand...
I will believe it when I see it. As far as we know they haven't even started on the engines. (3-stream follow-on to the F135 drop-in replacement.)
Click to expand...

Roper is slightly prone to overstatement; he really oversold the maturity of CD ATACMS.
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You wouldn't think that one would even be difficult. Slap a Harpoon seeker on ATACMs and call it good. (Yes, I know it;s more complicated than that, but all your lego pieces already exist.)
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Yeah. It's the JAGM seeker. And yes, it was sold like it would be here tomorrow. And you would think so.
But the Army indicates it's been delayed.
 
Whose to say the demonstrator isn't just a modified F-35 or F-22? Also, just because the airframe has flown, it doesn't mean it's packed with all the electronic 6th gen goodness.
 
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NUSNA_Moebius said:
Whose to say the demonstrator isn't just a modified F-35 or F-22? Also, just because the airframe has flown, it doesn't mean it's packed with all the electronic 6th gen goodness.
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My thoughts exactly. You could take a fifth-gen platform and stuff it with sixth-gen systems, maybe even powerplant, and technically claim it's a 'new' demonstrator because the system is more than the just the platform that happens to move your sensors and weapons around...i know, a bit convoluted but honestly i have a hard time a demonstrator of the relevant scale has been designed, built, and flown without anyone noticing things like surges of hiring at one of the primes. Usually there's telltales of these things.

That being said, if there is a brand new X-plane, i'm going to be stoked! :D
 

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