Air Force Legends: Northrop YF-23 ATF by Paul Metz

[GeorgeA]

Yeah, this book covers a lot of the development work and design studies leading to the YF-23. I was shocked by finding out what the final Rockwell submission looked like in this book; finally! This is another must have book.

Yes there's quite a bit about the Rockwell design, including some details about its evolution.

 

[SOC]

Absolutely incredible. The level of detail is astounding, although that was already apparent based on the screenshots posted a week ago. It even IDs the triangle bits inside the intakes that I noticed at the USAF Museum - vortex generators. I've only glanced through it a few times while trying to work, and it seems like some new or previously unknown (to me anyway) detail is found on just about every page. AIM-9 rails on weapons bay doors? Had no idea. My only "complaint" is that the performance figures for PAV-2 are still classified! If you have the slightest interest in high-performance aircraft, LO technology, the ATF program, or just want something really interesting to read, this one is highly recommended. There are a few other titles I hope to pick up this month (including Modern Chinese Warplanes, how the hell did I miss that one a few years ago, and yet another updated version of Crickmore's Blackbird tome), but this one may have my vote for "best of 2016" locked up.

Now, somebody convince Ginter to do a volume on the YF-12...

 

[aim9xray]

I was shocked by finding out what the final Rockwell submission looked like in this book; finally!

Reading between the lines, the Preferred Concept shown is "as of" the mid-CDI period; before the "stealth reset" described by Dan Raymer. It does illustrate the inward canted vertical stabilizers described by Raymer as a solution to a vortex problem found in the wind tunnel.

The actual final design submittal by Rockwell has yet to come to light (as well as any description or illustration of Grumman's design).

 

[Sundog]

I was shocked by finding out what the final Rockwell submission looked like in this book; finally!

Reading between the lines, the Preferred Concept shown is "as of" the mid-CDI period; before the "stealth reset" described by Dan Raymer. It does illustrate the inward canted vertical stabilizers described by Raymer as a solution to a vortex problem found in the wind tunnel.

The actual final design submittal by Rockwell has yet to come to light (as well as any description or illustration of Grumman's design).

Ahh, thanks for the clarification. I thought the inward canted verticals, squared wingtips and full under slung nacelles were the final submission. Well, at least we're closer.

 

[sferrin]

It was nice to see a bit of information on the FB-23. Would've been nice. :'(

 

[Madoc]

I got mine yesterday, direct from Steve.

This is an outstanding book. It's an excellent treatment of the subject and is almost overflowing with details. It's exceptionally comprehensive and in depth. This is one of Ginter's lengthier treatments and it's very well executed, the production value is high, and the quality of the book itself is outstanding.

I'm very happy with my purchase here!

 

[Sundog]

Something I noticed in the book is the model of the "production" F-23 (DP232) is actually longer that what is shown in the drawings of the production version. You can see the distance from the apex of the wing root, where the fuselage waterline goes straight forward from there, is longer than is shown on the drawings. You can also tell the canopy is further ahead of the wing than shown on the production F-23 (DP-232) drawings. Is this an error, a different "production" version, and if the latter, which is correct? The model or the drawing showing a production version?

 

[Anderman]

Any idea how i can get the book in Germany besides Amazon?

 

[Richard N]

Since Paul Metz was also chief test pilot on the F-22, I hope this is the title of his next book: Air Force Legends: Lockheed Martin F-22 ATF by Paul Metz

 

[flateric]

Any idea how i can get the book in Germany besides Amazon?

https://www.aviationmegastore.com/?action=prodinfo&art=139977

 

[icyplanetnhc (Steve)]

Finally ordered mine from Specialty Press, the only place that I could find it.

 

[Anderman]

Any idea how i can get the book in Germany besides Amazon?

https://www.aviationmegastore.com/?action=prodinfo&art=139977

Thank you

hopefully it´s back in stock soon.

 

[overscan (PaulMM)]

Received a review copy today (thanks, Craig!) and have had time for a quick browse through. Wow! excellent work all round, and some very cool new material I have not previously seen (some of which was declassified for this book) as well. Exceptionally comprehensive and thick (152 pages), this will keep me occupied for some time. Proper review to follow when I have finished reading it.

 

[Ogami musashi]

Something I noticed in the book is the model of the "production" F-23 (DP232) is actually longer that what is shown in the drawings of the production version. You can see the distance from the apex of the wing root, where the fuselage waterline goes straight forward from there, is longer than is shown on the drawings. You can also tell the canopy is further ahead of the wing than shown on the production F-23 (DP-232) drawings. Is this an error, a different "production" version, and if the latter, which is correct? The model or the drawing showing a production version?

Nice find, didn't even notice. Several points lead me to think the drawings are the most recent:
-On the model support you can read "FSD" instead of "EMD", the change in term was made later in the ATF program
-It seems the model is the "DP-201" (difficult to read on the last page, but on the firs were you see it from 3/4 aft it seems to read 201) which is earlier than 232.
-In tony chong's radical things book the DP-232 has the shorter nose


Tony told me the EMD proposal was a starting point and definitely changes would have occurred albeit not necessarily large. I guess changes of the mangnitude of what you spotted are possible so anyway it is possible we'll never know what the final production version would have really looked like...

 

[Richard N]

A few details about this model.

It is 1/72 scale from a stereo-lithography resin master. It is one of 30 made after the finished master model came back to the shop with a request for many more. An RTV silicone mold was made from the finished model and urethane resin castings were made. The 30 cast models were boxed and shipped and the finished model was cleaned, restored and returned.

 

[Sundog]

Something I noticed in the book is the model of the "production" F-23 (DP232) is actually longer...

Nice find, didn't even notice. Several points lead me to think the drawings are the most recent:
-On the model support you can read "FSD" instead of "EMD", the change in term was made later in the ATF program
-It seems the model is the "DP-201" (difficult to read on the last page, but on the firs were you see it from 3/4 aft it seems to read 201) which is earlier than 232.
-In tony chong's radical things book the DP-232 has the shorter nose


Tony told me the EMD proposal was a starting point and definitely changes would have occurred albeit not necessarily large. I guess changes of the mangnitude of what you spotted are possible so anyway it is possible we'll never know what the final production version would have really looked like...

Thanks, I thought the drawings were what was submitted but I just wanted to be sure. Overall, this book is an amazing piece of work. If you had told me that I would end up with this book and Tony's in the same year I wouldn't have believed it. It's been a great year for fans of Northrop designs and the YF-23.

 

[icyplanetnhc (Steve)]

Just got my copy today. I'm surprised that the F119 and F120 airframes (DP231 and DP232) have subtle differences in overall dimension. How much larger were the F120 engines? I wasn't aware of the increased size requirements for that motor. I believed the F-23A DWG that was released a few years back is the DP231, as that document explicitly listed the F119, hence the slightly shorten length than DP232. This also explains why the model and the DP232 DWG shows an extra small serration that the DP231 lacks. As for the longer nose on the model though, I'm not sure.

 

[tacitblue1973]

Just ordered mine today, it just seems too good a book to ignore, thanks for bringing this to my attention folks.

 

[lantinian]

Just got mine

So much stuff I always wanted to know. Very impressed by how the EMD configuration brings back features from the ATF proposal of 1986. It just proves how much more mature was Northorp's proposal at the time.

I was so excited when I ordered it I didn't notice I have ordered 2 ;D

 

[sferrin]

Looks like the production version would have been even faster than the YF-23 where they cleaned up the back end. :'(

 

[Ogami musashi]

Yeah the "less area ruled" argument wasn't true at all. it seems they also considered the by then future aim-120C and aim-9X. Since it seems they would use the same palet system as on the YF-23, according to my tries to fit aim-120C on the technical drawings perhaps 6 amraams were possible.

But we should discuss it in the appropriate topic...

 

[icyplanetnhc (Steve)]

Yeah the "less area ruled" argument wasn't true at all. it seems they also considered the by then future aim-120C and aim-9X. Since it seems they would use the same palet system as on the YF-23, according to my tries to fit aim-120C on the technical drawings perhaps 6 amraams were possible.

But we should discuss it in the appropriate topic...

Yep. In fact, the filling in of the volume between the nacelles is to actually retain the volume distribution of the YF-23 due to the F-23A's smaller nacelles (which also reduces surface area).

Pretty interesting read regarding the "input lag" of the YF120s.

 

[sferrin]

Pretty interesting read regarding the "input lag" of the YF120s.

That sounded like one of those items that, while annoying, would have been easily rectified had they chosen that engine to go forward.

 

[Ogami musashi]

Pretty interesting read regarding the "input lag" of the YF120s.

That sounded like one of those items that, while annoying, would have been easily rectified had they chosen that engine to go forward.

The linear thrust scheduling was interesting. There're probably some newer planes have it now (i think i heard the about that for te F-35) but what is the most impressive is the Integrated engine mode.

Curiously, while noted in Metz and Sandberg lectures there's no mention of flight by light on the YF-23, only fly by wire. However you do find the explanations for many words that were in the famous lecture and WMoF like "feet on the floor" for example.

One item i'm very curious about is the Boundary layer Control. As depicted in the book as well as in some scientific paper from 92 (AlAA 92-1076) the BLC seems just to remove turbulent BL air from the inlets. However the location of the exits and the fact that you had two doors per side plus an exhaust door, i wonder it there wasn't an aerodynamic blowing effect intended. Especially since in Tony chong's book, several prior BLC experiments with the aim of blowing the surfaces were done.In paul metz book, the BLC is described as having to different behaviors depending on the speed. The exhaust door was used at low speed but the two doors were used at supersonic speed to keep the bypass ratio as desired and reinjected above... interesting.

 

[sferrin]

One item i'm very curious about is the Boundary layer Control. As depicted in the book as well as in some scientific paper from 92 (AlAA 92-1076) the BLC seems just to remove turbulent BL air from the inlets. However the location of the exits and the fact that you had two doors per side plus an exhaust door, i wonder it there wasn't an aerodynamic blowing effect intended. Especially since in Tony chong's book, several prior BLC experiments with the aim of blowing the surfaces were done.In paul metz book, the BLC is described as having to different behaviors depending on the speed. The exhaust door was used at low speed but the two doors were used at supersonic speed to keep the bypass ratio as desired and reinjected above... interesting.

Reading the book I was a little unclear as to the function and location of those doors. They almost sounded like doors for dumping excess air at high speed like on the F-22 and XF8U-3 Crusader, as a way of controlling air pressure/shock position in the inlet.

View: https://www.youtube.com/watch?v=BKZrr4WbGYo

 

[tacitblue1973]

Just received my copy this afternoon. What a fantastic book. Very well put together and sizeable enough that everything doesn't feel crammed into too small a place. Quite noticeable how much closer to EMD specification the GE engines were sized. Noticed elsewhere that the YF119 engines had a first stage snubbed fan. I know they increased mass airflow for the production engine by about 15%. Still don't know the front fan diameter or mass airflow for any of them though. Most likely slightly more than a meter for one and mass airflow was ballparked somewhere around 335 lbs/sec by Bill Sweetman in the Fall 1999 WAPJ.

I'm not entirely convinced by that since the specific dry thrust per pound would be about the same as an F404-GE-100. I would have thought that a significantly hotter engine, with somewhat less BR and quite a bit more specific core power would perform better. Having related an image from the AF on the turbine radar blocker, how much efficiency did they lose?

 

[sferrin]

Just received my copy this afternoon. What a fantastic book. Very well put together and sizeable enough that everything doesn't feel crammed into too small a place. Quite noticeable how much closer to EMD specification the GE engines were sized. Noticed elsewhere that the YF119 engines had a first stage snubbed fan. I know they increased mass airflow for the production engine by about 15%. Still don't know the front fan diameter or mass airflow for any of them though. Most likely slightly more than a meter for one and mass airflow was ballparked somewhere around 335 lbs/sec by Bill Sweetman in the Fall 1999 WAPJ.

I'm not entirely convinced by that since the specific dry thrust per pound would be about the same as an F404-GE-100. I would have thought that a significantly hotter engine, with somewhat less BR and quite a bit more specific core power would perform better. Having related an image from the AF on the turbine radar blocker, how much efficiency did they lose?

Assuming published thrust figures are true. Consider that an F100-PW-232 with something like 275lbs/sec flow achieved 37,150lbs of thrust on a test bench back in the 90s. (The -229/232 run significantly hotter than the F110.) There's no reason to believe an F119 would be less capable.

 

[tacitblue1973]

I'm tending to think now that they're running it pretty conservatively especially for TAC durability reasons. I've heard how much more "effective" grunt the GE F110-129 has over the PW-229, simply because even though it runs hotter, it's the volume of effective heated mass airflow. Much like the supercruise differences were between the YF119 and YF120. Fixed bypass or double VABI architecture aside, airflow is king. Within inlet drag penalties anyway. Like between big and smallmouth F-16's. Thanks for the response sferrin.

 

[Ogami musashi]

Something I noticed in the book is the model of the "production" F-23 (DP232) is actually longer that what is shown in the drawings of the production version. You can see the distance from the apex of the wing root, where the fuselage waterline goes straight forward from there, is longer than is shown on the drawings. You can also tell the canopy is further ahead of the wing than shown on the production F-23 (DP-232) drawings. Is this an error, a different "production" version, and if the latter, which is correct? The model or the drawing showing a production version?

Aldo spadoni gave me some information about that. As Tony chong says in its book, DP231/DP232 were EMD proposal but were actually only starting point and not even the latest configurations at the time of the proposal. The were frozen as this to have coherent description along the proposal. One thing aldo told me is that the DP232 wasn't really detailled in the EMD proposal because the plan was to get to the DP231 three spike trailing edge eventually. The illustrations made by Aldo (that are in Paul Metz book) are actually neither DP231 or DP232 but a more refined version that whatever the engine had the 3 spike TE. As such his hypothesis is that Tony's model was actually the real DP232 (or close to) and that the technical drawing was just a placeholder since in any case the DP232 would be short lived.

Some other notes, while the "know only what you need to know" was the rule for the time (he was not only artist but avionics engineer during the EMD phase) he told me further iterations were already studied during the EMD phase but he doesn't recall any drawing from them.
He also confirmed me that fitting the aim-120c was envisionned but he doesn't know much more about this.

 

[Sundog]

Thanks for the info O.M. That certainly answers a lot.

Scott, with regard to the boundary layer doors on the top the reading definitely suggests that were used to keep the shock in the inlet optimized and prevent an unstart, just like on the Crusader III and F-22 as you noted. I also found the vortex generator within the inlet to control the flow through the s-duct interesting as well. Of course, what really caught my attention was Metz's statement that he considered the YF-23 the best handling fighter he had flown before, or since (F-22A), really says something about how good of an aircraft it was.

 

[Ogami musashi]

Thanks for the info O.M. That certainly answers a lot.

Scott, with regard to the boundary layer doors on the top the reading definitely suggests that were used to keep the shock in the inlet optimized and prevent an unstart, just like on the Crusader III and F-22 as you noted. I also found the vortex generator within the inlet to control the flow through the s-duct interesting as well. Of course, what really caught my attention was Metz's statement that he considered the YF-23 the best handling fighter he had flown before, or since (F-22A), really says something about how good of an aircraft it was.

That their primary goal is to optimize engine performance is obvious but since you have 4 different ways of exhausting (constant vents, blc vents, and two blc doors) it suggests there may be some though given as where and how they exit on the top surface.

 

[Richard N]

Paul Metz will be at the UT Dallas Eugene McDermott Library to do a YF-23 presentation Tuesday March 21, 2017. Details in the attached images. You will need the parking pass.

 

[icyplanetnhc (Steve)]

Reading the book I was a little unclear as to the function and location of those doors. They almost sounded like doors for dumping excess air at high speed like on the F-22 and XF8U-3 Crusader, as a way of controlling air pressure/shock position in the inlet.

View: https://www.youtube.com/watch?v=BKZrr4WbGYo

Interestingly, those doors just above and behind the intake are deleted in later production blocks. I remember seeing them on Raptor 4006 (background of my profile pic) and 4009 at Edwards during a UCLA engineering student tour about a year back, but they're absent on most production F-22s.

 

[Ogami musashi]

Paul Metz will be at the UT Dallas Eugene McDermott Library to do a YF-23 presentation Tuesday March 21, 2017. Details in the attached images. You will need the parking pass.

Cool, will you attend it?

 

[Richard N]

I will be there as well as a number of my friends. I met Mr. Metz a few years ago and at a plastic model meeting got to listen in on a test pilots conversation between him and Phil Oestreicher (first to fly the F-16). Wish I'd had an iPhone to record it back then.

 

[SteveO]

Great book (expensive for what it is though compared to other great books!).

One thing it didn't mention was the F-23's JDAM capability. Anyone know if it could deliver 2x 2000lb JDAMs or was it the same as the F-22 with 2x 1000lb JDAMs?

 

[flateric]

One thing it didn't mention was the F-23's JDAM capability.

Not surprising, because JDAM RDT&E has started in 1992, one year after F-23 lost the competition.
Second thing is if Northrop/MacAir were considering air-to-ground weapons _at all_ at the time (unlikely).

 

[Ogami musashi]

They did, but the configuration of the EMD (or to be more precise, THAT configuration) had no A/G configuration offered.

It was, according to aldo spadoni, considered (when?) and the plane would have JDAMs on one side, missiles on the others. Don't know if it was supposed to be 2K or 1K.

 

[BDF]

They did, but the configuration of the EMD (or to be more precise, THAT configuration) had no A/G configuration offered.

It was, according to aldo spadoni, considered (when?) and the plane would have JDAMs on one side, missiles on the others. Don't know if it was supposed to be 2K or 1K.

A few years ago Barry Watts mentioned that one of the reasons we should've taken the F-23 was because it could carry 2,000lb weapons. I messed around with weapon configurations with Sketchup and found that the GBU-31 won't fit. Three AMRAAMs could fit (per bay), but would have to have a unique configuration that isn't readily apparent. I'm fairly sure that the six AMRAAM was a classified requirement and the F-23 could meet that requirement but a 2,000lb class weapon will not; its too long and runs into the wing-join bulkhead.

Link to CAD pictures

 

[Sundog]

I believe he was probably referencing the YF-23 prototype, which had the single deep bay. But, once they, Northrop, realized that the USAF didn't like their weapons bay and didn't care about A2G in the ATF, the redesign most likely didn't need to consider the A2G option.