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

supacruze said:
The cross sectional area of the YF-23 was published in certain Northrop dwgs, but at this stage I'm not at liberty to elaborate more precisely. I can say that if you carefully study what has been publically released so far, you will see that the YF-23 did indeed conform more closely to the Area Rule than did the final F-23 configuration. This is because the fuselage shape of the YF did not have to accomodate equipment that would be installed on the production variant, so the 'waisting' of the fuselage could be more pronounced. The F-23 fuselage is thicker and more voluminous in certain areas to accommodate more weapons and fuel, particularly right at the wingtips, which is where you usually want it to be the slimmest. If you carefully scrutinise the YF in profile, you'll see that the longitudinal synchronisation between the wingspan and "waisting" of the fuselage is one of the most precise ever flown. In most area ruled aircraft, there is stagger between the extremeties of the wingspan and the narrowest point on the fuselage, but with the YF, you could draw a line laterally from the very centre of the wingtips and it would pass almost directly thru the narrowest point of the fuselage. This is very unusual.

This is quite an incorrect statement. As a matter of fact, the YF-23 was designed to carry equipment that the production variant didn't have to carry, namely thrust reversers. Also, you can't determine which had the better area rule by comparing the two against each other, you have to compare them to the ideal Sears-Haack volume distribution for a given Mach number to know how good they really are in terms of minimizing wave drag.

Edit: I should add, though, that the production variant of the F-23 has one of the smoothest distributions I've seen in a fighter design. About the only one I've seen smoother is Bud Nelson's N-353-4 (P900) design.
 
supacruze said:
Hi guys, I just found some new pics of the GE YF120 posted on Scott's site:
http://up-ship.com/blog/?p=12482

As much as I hate to say it, I wouldn't mind seeing that engine getting a quarter cut out of it so we can finally see how the variable cycle system was designed. I have ponderings as to how it was or could be designed, but I want to see for myself, unless someone actually has a YF120 engine cutaway drawing/image.........(still classified I would imagine?).
 
NUSNA_Moebius said:
As much as I hate to say it, I wouldn't mind seeing that engine getting a quarter cut out of it so we can finally see how the variable cycle system was designed. I have ponderings as to how it was or could be designed, but I want to see for myself, unless someone actually has a YF120 engine cutaway drawing/image.........(still classified I would imagine?).

There is one in Albert C. Piccirillo's book on the F-22. It's not particularly detailed, but it does show the general internal layout.
 
I'm curious about why the F-23 EMD didn't adopt a one piece canopy like the F-22. Unless the F-23's higher speed puts more stress on the canopy?
 
Different philosophy and engineering trade-offs for things such as bird strike durability?
 
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I found it interesting how ATF morphed from "Advanced Tactical Fighter" to "Advanced Threat Fighter" in the second picture. ;D
 
flanker said:
I found it interesting how ATF morphed from "Advanced Tactical Fighter" to "Advanced Threat Fighter" in the second picture. ;D

That is in reference to the adversaries, rather than the ATF.
 
quellish said:
flanker said:
I found it interesting how ATF morphed from "Advanced Tactical Fighter" to "Advanced Threat Fighter" in the second picture. ;D

That is in reference to the adversaries, rather than the ATF.

Ah right, MiG-1.44/42 etc. Still interesting.
 
Hypothetically, can fluidic thrust vectoring be fitted onto the F-23 to increase maneuverability? Or would the nozzles be too close to the CG so the moment be too small to really matter? Though it might not be necessary, since the YF-23 didn't need thrust vectoring to meet the ATF maneuverability requirements, unlike the F-22.
 
Was there any document specifically pointing toward the idea that the yf-22 needed thrust vectoring to meet maneuverability requirements set out by USAF?

Unless such document exists, stating that yf-22 needed thrust vectoring to meet maneuverability requirements is as logical as saying that unlike the yf-22, the yf-23 needed V-tail in order to meet stealth requirements.
 
For those who have YF-23 models, Caracal has just announced a new sheet for the YF-23 in 1/48 to be released in December.
I have suggested that he release 1/72 and 1/144 sheets as well. Please register your interest in these new sheets here:

 
flateric said:
Look at the pic. You will note that YF-23s weapon bay doors perfectly serve as deflectors of exaust plume both from AMRAAMs launched from retractable 'cradle' (other dubbed it 'cigarette pack') launcher moved into airstream (launch method in case of YF-23) and AIM-9s, launched from launchers installed on bay doors close to the edge. So in the case, YF-23 was superior to YF-22 with a cheek Sidewinders launchers. In the case of F-23A, with a additional AIM-9 weapon bay forward to AMRAAMs one, it would be a problem. I've asked a question to Pavel Bulat, why is a gury in wave dynamics and weapon bay aerodynamics. Let's see what he will say.

I believe that the only 'cigarette pack' was the one which showed AAAM in a tiltdown encapsulated container, first on the ATF, and then later on the F-14D. This podded missile system approach has a _LONG_ history behind it, in fact, if you look at some of the pictures of the early GD/Rockwell ATF configuration-


(which has been called a 'missileer' though it is clearly high performance, akin to the SDM not the SLO flying wing which the original F6D derived 'missileer' concept was noted as being) you will note that it seems to have this very same installation.

In the early 1980s.

Such a geometry is indeed similar to the old flip-top box cigarette pack.

What bothers me is that all known descriptions of the YF-23 weapons bay include only reference to a flat pallet, X3, layout of the AIM-120 AMRAAM. Which is simply not competitive with the known ATF requirements that the YF-22 met as being minimum four, preferrably six BVR shots, by suggesting that the sidebays (before the intake trunks were cropped back) were capable of AIM-120 AMRAAM carriage too.

The last X3 BVR shooter we had was the YF-108 firing 100nm capable nuclear GAR-X. Given the mixed history of long range weapons in general, something is very wrong in jets that are both credited with having met every requirement spec but the one which justifies the system: multiple fire and forget, very long range, attacks.

With that in mind, consider the following-

1. It's the AMRAAM.
A piece of junk missile whose 350lb weight and 7" case diameter classes were all nominally set by F-16 wingtip carriage requirements. On a jet which is larger than the F-15, this is utter sillyness. AMRAAM is actually longer than AIM-7M and yet AIM-7M with an airframe of 8" has a list range in the 52-56nm category with, presumably, an MH digital strapdown autopilot loft. Whereas AIM-120 has always been more modestly appraised at 35nm.

2. You did it where?
The YF-23 is touted as having done 'the hard part' of supersonic launch constraints validation out to Mach 1.5 vs. the 'for show' subsonic launches of the YF-22 team. But using LAU-106A/A ejectors to fire AIM-120 into a Mach 1.5 slipstream through open bay doors without mechanical assist as AVEL rams seems an exercise in YF-12 level positive ejector control.
Keep in mind that the design weapons solution was to clear multiple shots away from each other on a canted 20` index from vertical, which means that pallet has to come a long ways out or the AMRAAM risk a doorstrike. This creates multiple carriage box issues but more importantly, the pallet won't seal the bay, aero-acoustically, (it can't due to the swing down rotation of the trapezes which effectively mandates a large gap ahead of the pallet creating a potential 'vacuum pump' differential pressure effect in the void behind the pallet which the spoilers can only partly mitigate). What it will do is create a huge 'surfing' boundary layer interaction mode like a jetski.
I cannot image this as being an effective solution either.

3. It's a very expensive aircraft.
As I've said before, nobody in their right minds believed the spec sheet for the ATF would come in at 35 million. Not given what they were asking '+ stealth' in a dynamic maneuver airframe with the agility of an F-16 and the size of an F-15. The X3 pallet approach sounds like a save penny : spend pound, non-solution on what had to be a very heavily gold-plated system approach.

4. No See'em Too Good. NOT INVISIBLE TO RADAR.
Which means the farther you stay away from SARH and RFCG weapons, the better. Part of this is simple motor impulse. Part is extending and retracting a full rack into launch position underneath the single point attachment trapeze vee-frames. Which is apt to be both unstable, prolonged and a great waste of internal bay volume while presenting a flat panel set of corner reflectors to any radar that is able to look up vertically from below.

5. It's not inline with what earlier presentations had (mis?)represented the YF-23 weapons bay as having a rotary missile launcher and the AIM-120 as a 'compressed carriage' (aka folding fin) variant.
If you look at the YF-23 weapons bay, there are enormous 'patches' in the front and aft walls which could be covers for mounts of a rotary system. Comparitively, the trapeze vee-frames have little if any functional indication of utility (no hydraul connections, no rams or rotary drives etc.).

ARGUMENT:
I find it beyond suspicious that a generic weapons bay with no stealth features took so long to be photographed and when it was, it was a void, the primary weapons deployment feature having been removed. Why? The described system is not anything all that sophisticated. Why pull the pallet? Why show NO PICTURES of the high Mach tests when Lockheed made sure /everyone/ saw the AIM-9 and AIM-120 shots as both video and still?
Indeed, if you look at PAV-2 which is the only weapons bay aircraft we have seen, it makes even less sense-


Because fully a quarter of the forward end of the bay is blocked off by what appears to be cylindrical drive motor containers. Yet look at the distances and the lack of articulated struts between these and the trapezes. If the trapeze have a function, it is strictly as load suspension and pitch alignment (weapons were also canted downwards) not extension/retraction mechanisms.
In fact, I don't think it was a pallet at all. It may have been a pack. But if so, it was a very large one firing missiles that did not drop-clear as the Northrop story suggests, they forward fired as most AAAM illustrations show, from prepackaged tubes.
Alternatively, the rack was in fact a rotary and again, not a flat-tray or pallet.
Now, a conventional rotary launcher will not work in the YF-23 bay because it doesn't have the clearance margin to rotate a weapon past the roof (can't, in fact, if the trapezes are functional lift points). But what if it's not a conventional rotary?
What if it's a fixed spindle and the individual ejector rails, which function as LAU-142s from a complex stacked 'box' condition, rotate around it?
The USAF doesn't like to stack munitions in their internal weapons bays because doing so means that if a single unit fails, it sterilizes the entire system. But the LAU-142 was not pyro based cartridge ejector, it was pneumatic with both an on-rack bottle and aircraft supplied emergency ejection option.
Now, if a weapon doesn't intitialize, you drop it and retract the AVEL and then rotate down the next one. And this is possible by longitudinally displacing the individual launchers on separately geared drives, within or around the spindle.

Note the flaws in the following diagram of a three shot trapeze:
http://www.yf-23.net/Pics/Plans/PAV1 weapons bay schematic 1023.gif

There is no place for the pallet to rest that isn't potentiallly conflicted by the carriage box of the period AIM-120A/B weapon fins with their 21" spans, rotated sideways so that their controls extend even higher into the bay. There is no way for the trapezes to swing down without also (assuming fixed not translating pallet hinges) swinging forward and where you have 144" AIM-120s already longitudinally stagger-overlapped by at least 10" to clear the fins, this means you have less than 6" to clear the nose of the bottom most weapon from the bay edge as it passes the -shortest- point in the 160" bay, at the centerline notch.
I don't believe there is enough room for the system to articulate like it is suggested to and it gets worse when you consider door mounting the AIM-9Ms with their own 25" displacement from the panels (remember, the lateral AIM-120s are only partly extended into the airflow and have a 17` outward cant to their ejection axis).

CONCLUSION:
Something is wrong or misrepresented about the way the YF-23 weapons bays worked and particularly with the non-presence of the pallet in a nominally declassified (public display in unmonitored conditions) PAV-2 prototype weapons system.
Particularly with the still-hidden nature of PAV-1 whose weapons bay has never been photographed and the contradictory explanations of a rotary and palletized launcher system, at different pointsi in the DemVal program, it just doesn't make sense.
The USAF would not put an emphasis upon BVR solutions in a NATO, 'target rich', environment and then set the threshold so low on numbers carried in the minimum requirements as to convince the likes of McDonnell Douglas (X4 AIM-7, F-4 series, X6 AIM-120 F-15 series) that Northrop/MDD felt they could meet or exceed specs on a 'three will do' basis. Noth with weapons that have suffered from 10-30% historical SSPK.
With the prevalence of industrial espionage, it's a certainty that Northrop/MDD had spies within the Lockheed camp and they would also tell them that the YF-22 was a minimum four shot weapons platform.
If nothing else, a technical historical survey would reveal that the only fighter aircraft manufacturer to have ever gone with three was North American and Lockheed themselves and the YF-108/YF-12 didn't even get to FSD.
Either:
With tubed AAAM fired from a custom, 'dense pack', box launcher out of a Mach 1.6 parent, you have a 100nm+ firing zone as the ability to strictly avoid penetrating the escorts in taking down HVAs. Theoretically allowing a flight of four F-23A to engage and avoid as many as ten agile threats from as much as 50nm out before tackling the bigger fish.
Or.
You are expecting a variant of AIM-120 of sufficient compressed carriage modality as to be nestable on a rotary in sufficient numbers to make a five + two (with the center position over the spindle take by roof suspension gear) option plausible.
Or.
You are expecting a tandem carriage weapon like CUDA as a bolt replaces arrow shortened missile body solution and can afford to keep your weapons bays short and palletized as a result.
Any other condition results in a weapons system which, in my opinion, is by itself sufficient to default the platform from the program.
It may be telling that the final EMD design shows, not a 13'4" weapons bay but a tandemized 11' + 13.3' enclosure. Could the Northrop/MDD team have been awaiting a technical solution to their weapons bay issues which did not eventuate and thus been forced to revert to a (sleeker, prettier but HAS challenging) elongated shape for the EMD configuration?
And where does that leave strike?
 
LEG said:
I believe that the only 'cigarette pack' was the one which showed AAAM in a tiltdown encapsulated container, first on the ATF, and then later on the F-14D.

Very well though out and valuable post., IMO

Some thoughts, FWIW.

FWIW, only the GD proposal for AIM-152 (AAAM) was podded. Hughes' rocket-ramjet proposal wasn't. Wonder how it would have been mounted had AAAM gone to fruition and USAF actually adopted the system (which they said they wouldn't do). Have heard some speculation that it wouldn't fit in F-22's bay.

I do remember reading that although Northrop didn't talk much about their launching system, they did say it wasn't a trapeze. One other thing noted was that the launch mechanism would be modified for production to avoid the single failure sterilization concern you note.

Not sure what you mean by, " 'compressed carriage' (aka folding fin)". The compressed carry, to my understanding, was the smaller fins of the AIM-120C which, although not yet publicly revealed, development of which was certainly known to the two teams.

Regarding YF-12 and three missiles, in order to reduce cost for the prototypes they stuck the fire control in one of the bays, leaving only three available. It would have been repackaged for the production F-12B, and what few drawings/illustration we have of that indicate that it could use that bay for a fourth AIM-47, or in some depictions a cannon, which never made that much sense to me.

All in all, a fascinating post.
 
I don't think the YF-23 bay and launcher was in any way representative of the production system but was there just to fulfill DEM/VAL requirements.
 
PaulMM (Overscan) said:
I don't think the YF-23 bay and launcher was in any way representative of the production system but was there just to fulfill DEM/VAL requirements.

I believe Northrop/MDD said they computer and wind tunnel simulated the firings.
 
F-14D,

"FWIW, only the GD proposal for AIM-152 (AAAM) was podded. Hughes' rocket-ramjet proposal wasn't. Wonder how it would have been mounted had AAAM gone to fruition and USAF actually adopted the system (which they said they wouldn't do). Have heard some speculation that it wouldn't fit in F-22's bay."

The thing about stealth and LRAAM is that they are more positively reinforcing than most might assume, especially over a 'busy' air defense environment like NATO/WARPAC.

The Stealth jet gets reach-in to match it's new AESA lookin, a noted problem for F-15s trying to CAP threat baselanes as Iraqi jets came south to intercept the inbound raid columns was that the 25nm AIM-7 simply didn't have the oomph to hit threats at distances beyond which the 2,000ft shotfloor nominally protected lolo ingressers. Assume that's not an issue for an 'everyone's an indian' condition, 200 miles the other side of the cowboy fence and you still have an aperture lookdown restrictor that inhibits the jet from scoring in-close because the AESA is fixed and likely tilted upwards to keep from hogs nosing any radar that looked up when the radome was fenestrated to dielectric state. A long lance gives you a long E-pole standoff and the radar isn't look-angle scan limited from tracking through to impact because terminals comes about the point where you would be launching a Sparrow.

Now, there was mention of cheek arrays and the like on the F-22 from early on by I honestly don't know if there was space for that (or a proper fuselage inclination angle) on the YF-23 or not.

The Converse is also true, in that a supercruise shooter with some height on him, trying to chase down high value assets like Mainstay and Midas is going to be moving at a pretty good clip. And irrespective of what the pole boost provides, that means he's gonna catch a lot of shots in the teeth from the likes of SA-4/5/10 which, at altitude, have ranges well above 35nm.

Traditionally, this has been why the USAF has 'disregarded the Phoenix shots' as being impractical in a tactical environment. The Phoenix was slow. The AAAM with a relight terminal and a high energy loft from an ATF-23 would be anything but. And the _stealth aspect_ lets you remain essentially wings level and pointed at the target for the entire time of flight on the weapon. So that even if that A-50 is doing pylon turns around an SA-10 site, you can shoot it from as far as your weapons system will reach without worrying about a dozen other, 'minor' SA-2-3-6 threats beneath you.

"I do remember reading that although Northrop didn't talk much about their launching system, they did say it wasn't a trapeze. One other thing noted was that the launch mechanism would be modified for production to avoid the single failure sterilization concern you note."

See, I always thought that the LAU-142 was universal to the ATF program and had been in design all the way back in DemVal. It has an advantage in that, by extending the weapon away from the launcher roof/spindle mount, you can tandem stagger the fins so that total separation as carriage box volumetric numbers are determined by fin:body rather than fin:fin adjacency.

When I hear words like LAU-106A/A (which is basically a stubby ejector for insert into another pylon) and LAU-114 (which is essentially a vanilla Sidewinder analogue rail without the digitals to support a -9X, let alone a dropfire mode) it all brings me to a conclusion that the internals on the YF-23 were not terribly well thought out. And yet that cannot be because internal carriage is essential to both the low-RCS and the high-fast mission function of the entire airframe design. So you know they wouldn't be so careless unless there was a major technical shortcoming inherent to the design which they could not otherwise overcome within the DemVal period.

Of course, maybe the USAF evaluators were just doofuses.

You look at the Boeing PWSC, almost decade later with the (Ex-MDD) Phantom Works once more in the driver's seat on Boeing's ugly duckling and it's clear that the entire JSF DEMVAL downselect is flawed because there is no effective way to compare the tailed delta F-32 to the all-delta X-32. And the X-32's up and away performance -vastly- exceeded that of the X-35 in all areas except carrier approach and STOVL while the Boeing was much easier to manufacture.

Going back to the YF-23, I know I would not want to explain to my board why we thought it was necessary to go from a 13ft structural void to a 24ft equivalent in the middle of our new jet fighter, because we hadn't read the requirements document carefully enough.

And that's where things get interesting in answering your next question.

"Not sure what you mean by, " 'compressed carriage' (aka folding fin)". The compressed carry, to my understanding, was the smaller fins of the AIM-120C which, although not yet publicly revealed, development of which was certainly known to the two teams."

In a traditional rotary launcher, if you fold the fins flat, your principle concern in sizing the bay volume becomes how many weapons you can fit in a given cube of volume around the rotary spindle without touching the sides of the fuselage. The latter in turn having fixed limits as a function of frontal area, area rule and fineness ratio as 'pinch and flow' in fuselage design.

If you want positive control over the weapon all the way through the boundary layer flow field around the lower fuselage, another issue raises it's head however as even the most compact of long-arm rams-


Adds significantly to the spindle + ejector + missile condition. So much so that you can really only make it workable by biasing the spindle upwards towards the roof of the bay and widening the fuselage to accomodate a grape cluster effect whereby each weapon hangs at an angle below the other other and the rotation of the weapon axis is only sufficient to bring the new missile to vertical -after- the preceding one has left the jet clearing the space.

If you have fixed fins, however small, your rotary launcher is now designed around a presumption of a sterilized central volume and a clearance arc defined by the fuselage sidewalls while your total carriage count of weapons is determined by how far around the art tanget circumference of the spindle each weapon can be placed to ensure that your largest fin span doesn't interfere with the next weapon over (because the weapons are now no longer nestable, fin:body, at all).

Hence your spindle+ejector-arm defines not just the centerline to bay wall limit but the pie slice void of wasted space between weapon bodies defined by the edges-of-fintips not touching (almost as big as another missile body). And this so rapidly swells the belly as to become impossible to integrate within a fighter sized weapons bay enclosure.

Scraping the bay walls is still an issue but the missiles are effectively pushing each other apart as much as the bay is pushing them in, around the width of that spindle, removing the very reason for setting round objects around a round centerpole condition for volumetric efficiency reasons.
If you cannot fold missile fins it may result in a rotary launcher simply being incompatible within a fighter mission fuselage diameter.

For comparison, here is the B-1 CSRL loaded with SRAM-

See how fat that cluster is?

Standard AMRAAM fin span is 21". AMRAAM C/lipped fins are 19". AMRAAM body diamter is 7" by at least 50%. The GD AAAM had a 5" forebody and an 8" booster can. The difference, is fit the folding fins.

Now, there are alternative means to designing a /multiple/ launcher.

One, which I mentioned, is a reverse spindle as a mount for individual rotary collared launch rails which are sufficiently tandemized as to clear missile fins. The first missile is carried, oriented towards the bay opening, launches weapon and with the missile out of the way, the launcher retracts into a compact volumetric box so that the next round can rotate past it.

And then both those launchers can rotate away from vertical baydoor alignment as the missiles cycle in geared rotation around a _fixed_ spindle whose upper index point has suspension blocks of it's own, providing stiffness through a centerline keel as well as through end collars mounted to the weapons bay bulkheads.

Another option would be what I would call a 'hollow rotary' in which there is no spindle but rather the weapons are set in tubes with four point pin collars each end and racked on the walls of a frame matched to the shape of the fuselage. Let's call this a weapons cage. The upper and lower pins in each end of the tube collars provide secure mounting in the cage frame when maneuvering. And a robotic service unit moves on slide rails in each end of the cage, moving up to the roof or across to each sidewall to grab appropriate weapons from the wall racks with rotating docking clamp armatures.

As it docks with each chosen weapon, the clamp inserts it's own pins, cross-axially and the opposed pins in the cage mounts retract as the arm pulls the tube to a single door in the middle of the cage.

Obviously, this will slow firing rates and implies a single-point vulnerability as the weapons cannot reach the bay door opening if the robotic transfer armature fails. However; there are also benefits in that you do not duplicate multiple launcher arm volume/weight penalities. You can move towards a single bay door sized to the appropriate, maximum, weapon clearance envelope, greatly reducing the keel effects of an F-22 type bay mechanism and removing aeroacoustics from the issue almost completely because the missile tube blocks the bay opening until release.

While the entire cage, complete with outer-moldline stealthed, body contour matching skin can be extracted and replaced as a unit, rather like the 30mm ADEN package on a Lightning. Which further means that, when the cage is inplace, it locks with the fuselage and restores maximum rigidity to the fuselage station frames.

Because the tubes are universal, weapons handling inside the bay and ejection clearance through the boundary flow is largely a 'one shape clears all weapons configurations' compatibility condition even as downards canted pitch strakes on the docking collars force the encapsulation tubes away from the jet as the weapons fire through frangile covers at the front.

Whether you have an SRM or a JDAM or an MRM inside then doesn't matter because the wall mount docking racks on the cage walls slide up and down to provide separation indexing relative to the size of the tube and again, only the door has to be big enough for a 'biggest bang you want to drop' condition.

And then we come to this-

Which incorporates a more standard approach to a rotary launcher as well as some of the features I highlighted above. But importantly, it dense-packs _two_ missiles on single ram ejectors, right next to each other. Why is this critcal?

Because the weapons are doubled they have to eject off of paired (LAU-106A/A) stubs on-mount but when they drop the extending arm solution they cannot be tandem staggered t reduce fin clearances (if they are full finned and not folding). Further, since the patent was filed in 1985 and released to public view in 1987, just about the time the ATF team leads came back and said "Not good enough, we gotta start all over again...", it implies that the discontinuation of the launcher came about because the new configuration would no longer support it.

And last but certainly not least. This launcher configuration is compatible with a rounded upper fuselage sectional profile, was filed, not by Northrop.

But Lockheed.

If I may be permitted a further digression, let's talk about the Lockheed ATF design since so little has been revealed about the YF-23's design history as configurations.

First, here's the Boeing ATF concept submission-

Here is a later iteration-

And here is the Rockwell Missileer-

And here it is as a 'conventional' MRM carriage variant-

And here is the Lockheed ATF-

All big bellied, wide hipped, aircraft designed around a large wing supporting a big internal or external weapons carriage capability equivalent to _LRM_. Bigger than Sparrow. Not an MRM, 60% AIM-7's size/mass.

Here are the Boeing, Lockheed and GD ATFs together-


Whose 'blended' configurations supposedly lead to this-

At which point I have to object and press the BS Alarm button.


Why? Becasue what is it that all of these jets have in common with each other and -not- the Raptor?

They are long, weak, fuselage torsion body forms with just enough width to fit _one_ internal bay. Not three.

Something that might be indicative of a common solution deriving from a common weapon system/launcher configuration, coming to these companies out of the Black World.

Indeed, if you would believe Lockheed's official historiagraphers, the ATF design shape is essentially an F-117 flipped upside down.

That's wishful thinking based on facet angle reverse symmetries. Look at where the wings are that's what counts, structurally.

Midwing monoplanes have little in common with low or shoulder mounted monoplanes. Does an F-5 share more structural commonalities with an F-15 than an F/A-18?

Humbug.

The Lockheed ATF concept looks like a supersonic F/A-18.

a. It has a vertical or 'differential' area rule allowing a big spine as deep forebody with a
reduced engine area.
b. A long, uninterrupted yet, relatively slender underbelly with waist mounted inlets.
c. It has highly swept fins mounted directly to the fuselage engine nacelles.
d. It has an enormous LEX.

Now look at this-
And what do you see?

1. A sturdy if not chubby box frame fuselage sans discrete nose/engine/empennage
elements.
2. Sidebays on inlet trunking mounted ahead of the main bays, broadenign the shoulders of
the airframe.
3. Shoulder mounted wing leading to minimal differential rule and minimal structural
pathway issues with carry through along the entire corner of the box vs. internal volume
within it (midwing monoplanes have to size their fuselage ring frames to the amount of
torision and compression each individual frame will endure while connected via weak
longerons).
4. Very compressed, almost bodybuilder like squatness of the airframe. 'Powerful, not
Pretty'. It's area rule theory is limited to the extent that the afterbody doesn't exist as
much as reverse-tapers smoothly. It's a delta with integrated Stabs as TEF.

What is wrong with the F/A-18? What has plagued it's midlife decline?

Center barrel cracking due to both carrier landing stresses and the tendency of pilots to abuse it's high AOA capabilities by 'wheelie-ing' into high off angle missile pointing solutions.

What has plagued the early F-22 with possible sabotage from Russian titanium suppliers?

Poor annealing which led to severe cracks in the tailboom mounts.

In 1987, Lockheed's President, Sherm Mullin (sp.) came back from a meeting in which he had been _told_ that the jet wasn't up to snuff. And the skunkworks went into a major overhaul of the configuration, top to bottom, back to front that burned the midnight oil for about 3 months.

During TAC Brawler testing, the principle threat was found to be, not radar but IRST. The point by which turning across the scan arc of a GCI radar brought the attention of fighters was 20-30 miles past the point which a simple lighting of the afterburners would cause the threat to go pointer on it's own.

And yet the USAF wasn't worried about the MiG-23 or 25, both of which could outsprint the F-22 at similar heights, over considerable distances. They were afraid of the Su-27 and MiG-29 which had greater installed T/Wr to the prior generation but in no way to equal (wing sweep as aspect ratio + materials) their high Mach performance.

'All things being equal' as RFLO reduced frontal signatures, sensor wise, what's the difference between the Flogger/Foxbat and the Fulcrum/Flanker?

The earlier fighters have their IRST below a long nose. The other looks up from in front of the canopy.

What's the principle F-22 'last best move' SAM evasion? A 7G pull thru into a split ess that radically changes the intercept geometry by taking the slantrange downhill some 4-5 miles from FL50 at Mach 1.5 or better. Which is at least part of why it's built on a short, rigid, torque box fuselage, not a long, skinny, supersonic area rule superior, one.

i.e. Why it no longer looks like a cubist F/A-18.

Starting in the late 70s, the Syrians played red rover come over games with their MiG-25s looking into Lebanon and northern Israeli territory.

After Bekaa, the Israelis were in no mood for this kind of nonsense and set a trap. Using CH-53s, they heliportaged HAWK SAM to a mountain well north of their established lines, and shot up into the ground track of the Foxbat whizzing by. Whether damaged or simply out of energy and altitude in it's evasion, the MiG-25 was subsequently killed by F-15s (some versions of the story reverse the pusher-impaler roles).

Finally, the Soviets maintain a significant inventory of both long and short burn AA-10 Alamo IR variants with one of the first capabilities to 'ride the beam' of a simple RF uplink through the radar, boresighted to the IRST. This missile is solely associated with the Su-27 and MiG-29.

So what happened?

Something put a squirrel in the USAFs shorts, that's what.

Either a new radar or waveform became available to the Soviets, allowing them to detect the ATF baseline RCS and denying them the deep penetrating high-fast profile.

Or the USAF fighter pilot community decided they wanted more than a niche role, assassinating HVAs (the entire Tom Clancy 'Frisbees of Dreamland' first mission scenario in _RSR_ being a veiled threat if not an honest method indicator of what the ATF was supposed to do) as conventional options to dogfight with. And TAC Brawler supported this via issues with high-cold plume or Mach shock IRST tracking as burner use to change-lane in the 50K supercruise envelope.

Or a significant, blackworld and early LRM package/launcher mechanism hit a major stumbling block and did not eventuate.

With the result that we reverted to another (then) non-existent missile baseline which, because it wasn't really compressed carriage compatible (and never would be, even as the 120C) required a major change in the configuration of the fuselage.

The YF-23, with it's tubular forebody, was not adaptable to this late breaking change and the new, big-span, AMRAAM and the pallet/cradle system they kluged together to make it so was so obviously incompatible with the _mission requirement_ as much as bay design that they have hidden it's adhoc nature from the public for decades of embarrassment since.

IMO, it is highly indicative of the total structural failure of the YF-23 to be adaptive to the changed (?) mission profile that the NATF variant was in fact basically a different airframe that looked like the delta version of the Super Hornet 2000.

At some point, the USAF wrote or rewrote the specification in such a way that SD&M became SC&M and Northrop/MDD failed to pick up on the implications of this or knew it and couldn't do a thing about it because the USAF was demanding that they deconflict weapons on non-functional launchers as single point vulnerabilities which could sterilize the whole weapons bay. And the only answer was to cut an EVEN BIGGER (66-69ft fuselage increase overall, 13->25ft long weapons bay aperture cutouts in same) hole in the belly of their jet, to shift the Sidewinders forward and away from a conventional, pathetic, X3, AIM-120 side-by-side launcher pallet configuration.

The very slender, sleek, lines which makes the Ghost beautiful, also renders it torsionally weak as soon as you cut the longerons around the weapons bays.

Likely rendering the YF-23 'double inferior' as both insufficiently rigid to function as an SC&M platform and insufficiently armed, to be a viable BVR sniper when the AIM-120 is such a mediocre performer due to class limits deriving from it's F-16 compatibility compromise origins.

You will recall I said that explaining to the Northop/MDD board why the YF-23 lost the ATF competition when it was at least .4 Mach Points and 15-20db stealth superior from all aspects would be ugly?

Imagine what it means when the answer is: "The USAF wanted an airplane which could execute minimum 6G breakaway turns after firing a minimum four, discrete launcher redundant, MRM and we couldn't make our airframe both fast and rigid enough to compete because the launcher and/or encapsulate missile system we were relying on, broke in design."

Lockheed dumped their big internal bay design in 1987 by effectively rendering public their rotary launcher patent and going back to the drawing board on the airframe.

By compacting it to a squat pyramidal delta shape, they completely redesigned their weapons system to allow for discrete carriage of AIM-120 across a broad body and they dumped their '10%' as either STOL reversers, supersonic drag penalty or operating weight = fuel margin on a now 60,000lb jet to get sufficient transverse rigidity to support the enormous, hollow, spanwise, void in what became a big, flat, boxframe fuselage with a shoulder not mid mounted wing.

Or as the Russians call it: a Suitcase.

All this so that, even if the jet was detected, it could maneuver under the massive Q loads of supersonic speed sufficient to breakaway into cross track conditions that prevented threat missile shots from making the cutoff across a hypotenuse of changing range as opening range-rates.

"Regarding YF-12 and three missiles, in order to reduce cost for the prototypes they stuck the fire control in one of the bays, leaving only three available. It would have been repackaged for the production F-12B, and what few drawings/illustration we have of that indicate that it could use that bay for a fourth AIM-47, or in some depictions a cannon, which never made that much sense to me."

And I thought 2nm Aphids on the Foxbat was crazy... Maybe it was a death ray.

"All in all, a fascinating post."

Thanks!
 
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Considering the YF-23 was at least as maneuverable as an F/A-18 and in some parts of the envelope was more maneuverable than the YF-22, I can't buy into what your selling regarding maneuverability. The main reason the F-22 is a squat box is due to how they packaged the weapons bays, which don't allow for the carriage of strike weapons. The YF-23 was designed to also be able to deliver strike weapons from the start, and I don't just mean SDB's. I think that's the main reason they went with a single deep bay instead of the shallower tandem bays they ended up with on their final submission. Also, if the squat box was so much better structurally, it shouldn't have been so much overweight. Span loading is good at reducing structural weight, but you can't really consider those F-22 bays placed laterally across the airframe as really reducing the span loading. I think L-M did that more for C.M. management than any other reason.
 
Source for the YF-23 being "15-20db better from all angles" would be fantastic. Thanks. Never heard a number pegged to the "YF-23 was stealthier" idea before.
 
LEG,

Addressing some of your discussion,

I did find out how the Hughes AIM-152 would be mounted on existing aircraft. One of the requirements was that AIM-152 had to be able to use at least existing Sparrow mounts (remember this was early 1990s). In the case of the F-14D, at the time the only a/c that could use it to its full effectiveness, four would be mounted in the tunnel right where the AIM-7s went. Four more would be mounted on the shoulder pylons, using the AIM-7 and AIM-9 positions. Diameter of the Hughes/Raytheon missile was 9" as opposed to GD'/Westinghouse's 5.5", GD saying that up to 15 of theirs could be carried by the Tomcat.

Regarding cheek arrays on a production F-23, at the time USAF wasn't willing to accept the narrower field of view that is a byproduct of an AESA antenna. Therefore, the choices to overcome that would have been side arrays, as used by the PAK-FA/T-50 and originally planned for F-22, or a mechanically movable AESA, as espoused by Captor-E. I don't know Whit they planned for whichever avionics system USAF selected, but I doubt if anyone thought of the rather elegant solution that SAAB is using on the Gripen E.


Phoenix is not the fastest accelerating missile off the aircraft, but it keeps speeding up. Top speed is M3.5 plus launch speed, up to a max of M5.5, which isn't exactly snail's pace. As to why USAF didn't like the 'Phoenix shots' in those days, I think there are three reasons. First, "NIH", it's a concept invented by the Navy. Second, it might be perceived as a threat to funding for the F-22. Don't forget, USAF kept playing down requirements for A2A capability in JSF requirements until they accepted that they weren't going to get any more F-22s. Third, it's not macho.

USAF evaluators were not doofuses, if I understand your point. Remember that the evaluators never got to compare the a/c to each other, only to how well the design they were evaluating (the evaluators were kept separate from each other) met the criteria points through a series of "stoplights". This is discussed in more detail elsewhere. They were the ones that identified the issue of one jammed missile blocking all launches, which Northrop showed how they would address that in the production model, to their satisfaction.

My question regarding "compressed carry" was in light of what was going on then. Although it hadn't been publicly announced, the contractors unquestionably had to have been briefed about the forthcoming AIM-120C. They would have to in order to optimize their design. So they knew that the new AMRAAM had clipped, not folding, fins. Knowing this it wouldn't be prudent to design a launching system around the characteristics of missile that wouldn't exist.

Regarding the F/A-18 and its midlife decline. Part of it is that it, like most other a/c we have, has been flying many more hours faster than projected without a comparable increase in maintenance funds. Regarding the "wheelie", high AoA is the Hornet's air combat trick. They will and have to,use it as much as they can. Also, although it's a fine a/c, having talked to a number of maintainers over the years, they say it's not as rugged an airframe as was the F-4 and F-14. helps keep the weight down, I guess.

What significance do you ascribe to the location of the IR/IRST on the Soviet a/ you mention? In US a/c they've been located above (F-101, F-106, F-8, etc), below (F-4, F-14, F/A-18E, NATF and probably F-22) and both (F-16, F-15). I'm not counting the F-12B which would likely have had two on the sides because it never entered production.

Regarding the "...it is highly indicative of the total structural failure of the YF-23 to be adaptive to the changed (?) mission profile that the NATF variant was in fact basically a different airframe...", then what is your opinion of the Lockheed NATF design, which Lockheed said was so different that it would have to be built on a separate production line?

I agree that IR was developing to be a more potent counter-stealth technology than originally envisioned, but it certainly appears that the YF-23 design took this into account much more than did the YF-22.

I, for one, am enjoying your analysis. When the Secretary of the Air Force looked at the two independent reports and made his decision, he mostly focused on the backup documentation as the reason for the choice. MDD itself said afterwards that they should have done a better job on that. There were some questions unofficially raised about whether Northrop could indeed produce a single piece structure of the size and shape of the center section, but the fact that two aircraft were sitting on the ramp seemed to indicate that they could.

A question does spring to mind: If the Northrop/MDD YF-23's missile launching system and operation were as inferior as your analysis seems to indicate, why didn't the Air Fore just come out and say so, and say that's why they picked it? They stated why the MDD design was picked for the F-15 (even over the NAA design which some said had higher performance), why the YF-16 was picked over the YF-17, the A-10 over the A-9 and the X-35 over the X-32. It seems to me that the weapons operation would be a major factor and certainly would be a non-controversial and totally understandable reason for selection. So, why didn't they just come out and say it?


Again, a fascinating piece.
 
I have personally spoken to the chief engineer of the YF-23 and he said it had a pallet system. The pallet schematic is shown in the dwgs accompanying Northrop's XF-23 NASA Proposal. This same proposal quotes provision for 3 AMRAAMs and 2 AIM-9s. The YF-23 was not intended to emulate the final F-23A weapons bay config. I asked him about details on the F-23A and he refused to comment.
 
Sundog said:
Considering the YF-23 ... in some parts of the envelope was more maneuverable than the YF-22


As I remember the YF-23 was stealthier and faster then the YF-22 (weither with PW YF119 or GE YF120), whereas the YF-22 was more manoeuvrable, especially with regard to WVR manoeuvres. Of course the YF-22 already had TVC, whereas the aft-design of the YF-23 prohibited TVC-installment.
 
Dreamfighter said:
Sundog said:
Considering the YF-23 ... in some parts of the envelope was more maneuverable than the YF-22


As I remember the YF-23 was stealthier and faster then the YF-22 (weither with PW YF119 or GE YF120), whereas the YF-22 was more manoeuvrable, especially with regard to WVR manoeuvres. Of course the YF-22 already had TVC, whereas the aft-design of the YF-23 prohibited TVC-installment.

What's leaked out over the years was that both designs exceeded the requirements for maneuverability. The consensus seems to be that the YF-22 was more maneuverable on the left side of the envelope, especially in the lower left. This is believable, because that's where TVC has the most effect. TVC helps you point the nose, and at high AoA/low speed can make a big difference, but it doesn't make you turn tighter. As speed increased, the advantage lessened and some say disappeared completely. TVC would have less benefit at higher speed, but it would be a more (radar) stealthy tool for trim.
 
However, where the TV does help in the right side of the envelope is in lowering trim drag. you can use the TV for trimming, lessening the overall trim drag on the right side of the envelope.
 
I wonder roll rate of the yf-23 fair against the yf-22. Yf-23's body creates great lift but would means suffering in roll rate I believe. Don't know if or how the horizontal tails and the diamond wings would factor into this.

Regardless, I truly believe has the yf-23 been chosen, it could have become a much more flexible aircraft than the yf-22. The exclusiveness of the air superiority is no longer relevant today, thus I believe the yf-23 could have made for a far better deep strike asset or the so relevant to the missile defense mission today.

During Desert Storm, it was a real pity that many fighter pilots could only watch helplessly against Scud missiles without ability to strike them down. The yf-23 with its rear stealth and higher speed can fly deep in the enemy's airspace to hunt missiles in the ascending stage. The deeper weapon bay and the fact that the WVR missile and the BWR missile bays are adjacent means that they could be modified to form a longer bay to accommodate a large ramjet missile to hit these time critical target.
 
donnage99 said:
I wonder roll rate of the yf-23 fair against the yf-22. Yf-23's body creates great lift but would means suffering in roll rate I believe. Don't know if or how the horizontal tails and the diamond wings would factor into this.

The tailerons were massive, and IIRC, I believe the wing control surfaces could also operate differentially
 
Was there ever a reason given for why the EMD F-23's chine is much less pronounced than the YF-23's? Also, it seems like the F-23 would need a radar blocker as well, since the engine compressor face is visible.
 
Sorry but I failed to see how the production model's chine is less pronounced. And I don't think the engine is visible given that the production model uses divertless inlets like f-35
 
Could it be an illusion based on the reshaping of the nose to accommodate a radar?
 
donnage99 said:
Sorry but I failed to see how the production model's chine is less pronounced. And I don't think the engine is visible given that the production model uses divertless inlets like f-35

The production model's nose has a cross section like the F-22's nose; there it isn't a "lip" so to speak, like the YF-23 has at the waterline from the front of the wing to the nose. My guess is they did it because it probably reduced production costs and was aerodynamically just as beneficial as the YF-23's without hurting signature reduction.
 
donnage99 said:
Sorry but I failed to see how the production model's chine is less pronounced. And I don't think the engine is visible given that the production model uses divertless inlets like f-35

In this rendering of the F-23 by user named Stuka, which I believe is based off declassified schematics, shows that the engine compressor face is visible. Of course, I don't know how accurate this model really is.
 

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The engine face is only visible from an odd angle and there may have been a fan blocker as well. I'm quite sure Northrop knew how to mitigate the fan face return and they aren't about to tell us. ;)
 
Sundog said:
The engine face is only visible from an odd angle and there may have been a fan blocker as well. I'm quite sure Northrop knew how to mitigate the fan face return and they aren't about to tell us. ;)

This is true. As these pictures I stole borrowed from the excellent YF-23.net site (reproducing the Koku-fan and World AirPower Journal drawing) show, the engines were buried in the fuselage and were not in line with the front intakes. The front compressor faces would not be visible. No compressor faces would be visible even without the radar attenuators that would have been in the redesigned intakes of the F-23A. Northrop wouldn't screw up like that.
 

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Grey Havoc said:
I think that this is the original trailer for that program:

I actually think it's a trailer for a DVD about the YF-23 that I've got stored somewhere. I think they used to sell it at the Western Museum of Flight (where PAV-2 now resides), but I don't know if it's still in print.
 

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