Northrop / McDonnell Douglas ATF - YF-23 and EMD F-23

[ADVANCEDBOY]

For me this airplane is a benchmark in jetfigter design. Absolute beauty this beast is. I have no choice but to do my best to match it one day. Now back to practising....

 

[Radical]

Has the YF-22's supercruise speed with the YF-119 engine been declassified? According to Paul Metz, the YF-23 reached mach 1.43 with those engines.

I don't think that speed remained classified, if it ever actually was. The only one that stayed classified, and still is AFAIK, was the YF-23 with the YF120 engines.

Hmmm, it's strange because I've never found YF-22's YF-119 speed anywhere. I'm listing the official speeds below.

YF-22 w/ YF-119: ???
YF-22 w/ YF-120: M. 1.58 (official declassified speed)
YF-23 w/ YF-119: M. 1.43 ("standard day supercruise speed" according to Paul Metz in AIAA 92-1039)
YF-23 w/ YF-120: Classified

I would guess YF-23 with YF-120 reached 1.8, possibly 2.

 

[overscan (PaulMM)]

According to David C. Aronstein, Michael J. Hirschberg, Albert C. Piccirillo in

Advanced tactical fighter to F-22 raptor: origins of the 21st century air Dominance Fighter


YF-22 No 2 (YF-119 did supercruise at Mach 1.43 (YF-119) on Dec 27 1991.
YF-22 No 1 (YF-120) did supercruise at Mach 1.58 on Nov 3 1991, the latter stated to be the maximum achieved with this aircraft.
YF-23 No 1 (YF-119) did supercruise at Mach 1.43 on Sept 18 1991.
YF-23 No 2 (YF-120) did supercruise at Mach 1.6 on Nov 29 1991. This is not actually stated to be the maximum achieved with this aircraft.

 

[Sundog]

I'll have to check my AW&ST articles, but IIRC, the max supercruise achieved with the YF-23/P&w engine was around M=1.8

 

[flanker]

Well, i knew it was fast, i was thinking around 1.6 mach fast. If it really was 1.8+, then my face just melted out of sheer awesomeness...

 

[F-14D]

I may have posted this elsewhere, so sorry if I'm repeating myself.

In the middle '90s I was talking with an official who was not part of the evaluation team, but would have been involved with the logistical support of the ATF/F-22 had the original plans been followed. I mentioned that the supercruise figures of the YF-23 with the YF120 engine were still classified, whereas all the other ATF combinations were not. His opinion (and it was his opinion, not a statement of fact; he wouldn't be in a position to know) that if it was still classified, "...then they probably did M2". I have

FWIW

 

[AAAdrone]

It seems weird that the supercruise performance figures of the P&W powered aircraft would be the same. Also if the figure was indeed mach 2 for the PAV-2/YF-120 combo, then I would officially be astonished beyond a reasonable doubt. It's times like these where I wonder if the F-119 will be compatible with an ADVENT style third flowpath/extra duct for a possible future upgrade? It might be a bit overly complex but still, one can dream.

Also Sundog, don't you mean the YF-23/GE combo? It is already understood that both P&W powered aircraft achieved mach 1.43.

 

[Sundog]

Once again, based on info from AW&ST, IIRC, the YF-23/GE combo's max supercruise was M=2.2 and other sources report it's top speed around M=2.8+. Though I haven't any doubt if it did reach that top speed it would have been quite limited based on airframe heating. IIRC, that's what set the limit for the ATF design's one hour supercruise design spec limit, the ability to absorb the amount of heat generated in that time.

 

[AAAdrone]

OMG! Mach 2.2?! That just makes me love the YF-23 even more! To think that aerodynamic heating was the main limiting factor of speed performance as opposed to aerodynamic issues such as drag and the limitations on efficiency/performance inherent in a fixed geometry inlet/intake really does serve as a testament to the wonderful engineering prowess of Northrop and MDD!

 

[sferrin]

Well, i knew it was fast, i was thinking around 1.6 mach fast. If it really was 1.8+, then my face just melted out of sheer awesomeness...

The F-22A will supercruise at Mach 1.7+ (Jay Miller puts it at Mach 1.82).

"“Today I flew the Raptor at speeds exceeding (Mach 1.7) without afterburners,” General Jumper said.“To be able to go that fast without afterburners means that nobody can get you in their sights or get a lock-on. The aircraft’s impressive stealth capability, combined with its super cruise (capability), will give any adversary a very hard time.” (Courtesy of Air Education and Training Command News Service)"

 

[unclejim]

Better have a tanker nearby before and after that!

 

[sferrin]

Better have a tanker nearby before and after that!

It wasn't using afterburner.

 

[Radical]

I'll have to check my AW&ST articles, but IIRC, the max supercruise achieved with the YF-23/P&w engine was around M=1.8

That's blistering fast. The plane certainly looks like it can punch through the air at such high speeds. Although I'm confused as to why Paul Metz stated that the plane with YF-119 only achieved mach 1.43. Was he deliberately downplaying the aircraft's speed to maintain classified information?

 

[Arjen]

Better have a tanker nearby before and after that!

It wasn't using afterburner.

You're moving ~30 tonnes at M1.6+. Even without A/B, you're making Exxon very happy.

 

[flateric]

other sources report it's top speed around M=2.8+.
Though I haven't any doubt if it did reach that top speed it would have been quite limited based on airframe heating.

I bet composites used in YF-23 plainly limit her max speed to something about M=2.35 at 40.000

 

[lantinian]

I think one can take an educated guess at the max super cruise speed of the YF-23/YF119 combo by the method they employed in testing. They accelerated the aircraft to the theoretical max supercruise speed in afterburner and then switched back to full military power and allowed to plane to reach speed/trust equilibrium. B)


All public statements by Northrop personal say the aircraft flew faster than expected.



Official sources point to the YF-23/YF-119 reaching Mach 1.8 with afterburner. Speed/Altitude chart from the testing also show Mach 1.8 being the fastest testing point planned but clearly no the fastest the airframe can achieve.


My rhetorical question is:
Why would Northrop chose to test the YF-23/PW up to Mach 1.8 with afterburner when this is neither the design limit nor a program requirement? :


The only answer that makes sense to me is that it was in support of establishing the maximum supercruise capability of the airframe. This speculation is backed further by the fact that the YF119 were the more mature engines (being delivered according to the original 30,000 trust requirement) and both Lockheed and Northrop chose the PW powered prototypes as the workhorse for the test program.


Northrop famously finished the YF-23 DEM/VAL program with the YF-23/PW performing 6 sorties in 1 day and still finishing in condition 1 > ready to fly again. The Mach 1.8 number was also reached on that day.


Actually, instead of dusting off my memories, how about I dust off something I created back in 2008 as part of an article about this topic. Updated and fleshed up a bit.

And here is the google docs file

 

[sferrin]

other sources report it's top speed around M=2.8+.
Though I haven't any doubt if it did reach that top speed it would have been quite limited based on airframe heating.

I bet composites used in YF-23 plainly limit her max speed to something about M=2.35 at 40.000

Depends what they're using. There are forms of BMI good up to 500F+ .

 

[flateric]

http://www.secretprojects.co.uk/forum/index.php/topic,1092.msg26550.html#msg26550

 

[unclejim]

F-22 still a fuel guzzler in "supercruise" and needs tanking up after such operations. More Air Force hoo-ha!

 

[sferrin]

F-22 still a fuel guzzler in "supercruise" and needs tanking up after such operations. More Air Force hoo-ha!

Any idea what the sfc of an F119 in dry thrust is vs the sfc of an F110 in afterburner?

 

[AAAdrone]

I don't know the exact numbers, but all I know is that that ratio of sfc for F-119 vs. F-110 is a LOT less than 1:1 that's for sure!

 

[Radical]

And here is the google docs file

Are you sure you got the estimated thrust for the F-120 right?

Or doesn't variable cycle produce that much more efficiency at high altitude/speed.

Also, where did Mach 1.82 for the F-22 come from? IIRC, the highest supercruise speed released by the Air Force is Mach 1.78. I also can't help but wonder how much the extra weight that the F-22 gained vs. the YF-22 hurt the potential speed. Is there any reason to assume that the F-23 wouldn't have the same weight control issues?

 

[sferrin]

Also, where did Mach 1.82 for the F-22 come from? IIRC, the highest supercruise speed released by the Air Force is Mach 1.78. I also can't help but wonder how much the extra weight that the F-22 gained vs. the YF-22 hurt the potential speed. Is there any reason to assume that the F-23 wouldn't have the same weight control issues?

Mach 1.82 is listed in Jay Miller's book. The 2.42 I'd guess is from Paul Metz's quote about "the top speed is secret but it'll do 1600 mph".

 

[F-14D]

I also can't help but wonder how much the extra weight that the F-22 gained vs. the YF-22 hurt the potential speed. Is there any reason to assume that the F-23 wouldn't have the same weight control issues?

Only in the sense that the changes to go from YF to F on the -23 were said to be not as extensive as on the -22, although there would be some fuselage stretch to accommodate all of the front missile bay.

As far as speed goes, my understanding is that the F-22 is faster than the YF, but the a/c carries less fuel.

 

[AAAdrone]

I believe the reduction in fuel was called for by the AF as I seem to recall reading somewhere that out of speed, maneuverability, and range, Lockheed stated that the AF had to pick any two of those performance criteria to optimize the a/c for. The AF decided to sacrifice the latter characteristic to increase speed and maneuverability.

 

[F-14D]

I believe the reduction in fuel was called for by the AF as I seem to recall reading somewhere that out of speed, maneuverability, and range, Lockheed stated that the AF had to pick any two of those performance criteria to optimize the a/c for. The AF decided to sacrifice the latter characteristic to increase speed and maneuverability.

I think I wrote something similar to that elsewhere on the Forum. I believe I phrased it isomething like in going to EMD and thence production Lockheed advised, "We can meet the requirements for speed, range, maneuverability. Pick any two".

 

[Radical]

I also can't help but wonder how much the extra weight that the F-22 gained vs. the YF-22 hurt the potential speed. Is there any reason to assume that the F-23 wouldn't have the same weight control issues?

Only in the sense that the changes to go from YF to F on the -23 were said to be not as extensive as on the -22, although there would be some fuselage stretch to accommodate all of the front missile bay.

As far as speed goes, my understanding is that the F-22 is faster than the YF, but the a/c carries less fuel.

I recall that one of the reasons that the F-22 gained so much weight is that they had to replace quite a lot of composites with titanium because of strength and ballistic impact concerns. It's rather surprising considering that the F-22, which is noticeably more slender than the YF-22, is 13000 lbs heavier (43000 lbs empty vs 30000 lbs empty).

From the drawings, the F-23 doesn't seem to have lost any bulk compared to the YF-23, although it appeared more slender due to its increased length. If the F-23 also ran into problems incorporating composites, it's possible that it may gain even more weight than the F-22 did.

 

[Sundog]

I recall that one of the reasons that the F-22 gained so much weight is that they had to replace quite a lot of composites with titanium because of strength and ballistic impact concerns. It's rather surprising considering that the F-22, which is noticeably more slender than the YF-22, is 13000 lbs heavier (43000 lbs empty vs 30000 lbs empty).

From the drawings, the F-23 doesn't seem to have lost any bulk compared to the YF-23, although it appeared more slender due to its increased length. If the F-23 also ran into problems incorporating composites, it's possible that it may gain even more weight than the F-22 did.

I would actually trust the weight figures from Northrop, more so than Lockheed at the time, simply due to their extensive knowledge with large composite structures, re: B-2. Besides, bulk in and of itself isn't the problem. It's the lift and thrust and drag that go with it that determine how well it will turn out.

Of course, the fact that F-22 was so much heavier than the YF-22 leads me to believe that even our "prototyping" in competitions leaves a lot to be desired, since the end product is so different from what's first flown. It practically renders the competition useless.

Granted, all of these problems aren't the contractors fault alone. Many of them start and end with the Pentagon and ever changing mission needs and "gold plating" the system. At this point in time the Pentagon could definitely use a new Boyd, but that isn't going to happen.

 

[AAAdrone]

Even if there was a weight gain from YF to F for the F-23 I'd imagine the changes made to the airframe design would help make improvements in certain capabilities despite making some sacrifices. For example the F-22's inlets aren't the same as the YF-22's. Who's to say that Northrop wouldn't have been able to develop their inlets to offer a vastly superior stagnation pressure recovery by the time the flow gets to the engine face? It isn't just the engines that are responsible for aircraft performance so the performance of the prototype to production model may actually increase regardless of weight gains.

As estimated earlier there should have been a reduction in frontal and wetted area so the parasitic drag should be reduced and even if the area ruling is reduced from the prototype to accommodate a better payload bay and avionics suite then that is where the presence of trade-offs becomes apparent. You can't have a fighter that looks like the Sears Haack shape and expect it to actually fulfill the military's requirements. It's good to area rule an aircraft, but to do it perfectly would mean sacrificing other important characteristics like being able to hold a radar and an ESM system and the like.


Which reminds me, were there any new methods of laminar flow control/boundary layer suction incorporated in the EMD F-23 variant? I'm aware of those patches in front of the inlets that were supposed to suck the thin and not-so-turbulent boundary layers and discharge them through the upper surface of the airframe before they became an issue but I don't see them on the EMD blueprint. Thanks in advance.

 

[Radical]

Given the low number of F-22s in service, is it possible that the F-22 get something like enhanced composite wings and other structures that takes advantage of advances in technology in a future SLEP program?

 

[flateric]

PAV-2 at new WMOF place at Louis Zamperini Field
late autumn or winter 2011-2012
http://www.helikopterhysterie.com/2012/01/stealth-star.html

 

[flanker]

Given the low number of F-22s in service, is it possible that the F-22 get something like enhanced composite wings and other structures that takes advantage of advances in technology in a future SLEP program?

They made 6 sets of extra wings before the Raptor line was closed. So it doesn't seems like they are interested in making completely newly designed wings just yet.

 

[Radical]

I did a rough blackout of the silhouettes. The top is the YF-23 and the bottom is the F-23A. Thanks to Scott Lowther for the outlines. The F-23A does seem to have a much smaller frontal area than the prototype.

 

[flateric]

one of her best shots

 

[quellish]

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[quellish]

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[F-14D]

Came across an interesting bit of information from the past...

In a recent interview, one of the members on the YF-23 team noted that the YF-23 could fly an entire mission at M 1.4. Now we know that the YF-23s supercruise was much higher than that, its ultimate number remains classified. So I take this to mean something else. The specifications for the solicitation required the aircraft to be able to achieve a certain range, with a (still) non-disclosed portion of that in supercruise. In other words, you had to be able to fly X total miles, and part of that being in supercruise of a certain minimum speed. This seems to say that the YF-23 could launch and fly the entire mission in supercruise at at least M1.4 while still meeting the total range requirement. I wonder if that included a certain amount flown at the higher supercruises of which it was capable.

Quite an aircraft...

 

[lantinian]

This totally makes sence.

The major limiting factor to F-22's super cruise duration is the heat build up from the two engines working closely side by side.

The YF-23 design avoided that in at least 4 ways:
- could fly as fast as the YF-22 at lower throttle setting > less generated heat & lower fuel consumption
- the engines are further appart > no heat build up in between
- Aft section with a much greater surface area > engines have more cooling area
- no TVC > less trust is lost and converted to heat & better fuel consumption

B)

 

[flateric]

I strongly remember that YF-23 PAVs HAD HAD problems with engine bays unpredictably high temperatures though
like 'designers thought that they will get high T from aerodnamic heating in engine cowlings that - as it turned out - were less than they got from engines itself'
it was in Polish book that was in fact one of the best compilations of program development tidbits published in open press here and there

 

[Ogami musashi]

F-23 would have had far closer nacelles spacing; I wonder if that was really an unsolvable problem;


I actually browsing archive to try and found when did the requirement for supercruise range went down but have trouble finding it; back in 95 the F-22 was still planned to make 15 tons empty (even with the approved weight increase) so that's probably somewhere between 95 and 99 that requirements were lowered; Another possibility is that requirement were relaxed far before probably in 92..