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1 hour ago, TheBadger said:

I think they were on your site.  At least there were a few. If you have other I'd like to a copy as well if you don't mind.


They were never posted on my site - or any other that I know of.  They are buried somewhere in my "archives".....


These were large multi-sheet drawings, and were pieced together from xerox copies.  They are surface plots of panel lines, top and bottom, and cross-sections, both transversa and lateral.  There is no internal detail, gear, cockpit info, etc which is why I think they were intended only for the model shop. 



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So started some work on the Planet Hobby A-12 last night.  Opened up the bomb bay and missile bay.  Looking at the exhaust which is the better represented?  Anigrand on left Planet Hobby on right.  


Edited by TheBadger
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  • 6 months later...

Look here for pictures of mock-up and conceptual images: http://notreally.info/transport/planes/avenger_ii/a-12/img/

By my eye, neither one is totally "correct". That said, I doubt the mock-up would show the actual expected configuration of the exhaust(s), as these were usually a closely held secret on stealth a/c. My first viewings of F-117 and F-22 were with the a/c backed up to a wall, cordoned off, and armed guarded. There is at least one concept/engineering drawing out there that shows twin exhausts.


Edited by CorsairAU1
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  • 3 years later...

A-12 Mockup, Cockpit Side Consoles



A-12 Exhaust (very little to see, serpentine Coanda, like on the F-117...)



I would be -very- careful about using the supposed '1:1' A-12 mockup as the basis for any scratchbuilding.


It looks subscale to me, for a jet which has a 70'3" wingspan.  Take a gander at the blue shirted tech trying to close the canopy at 2:50 in the first video.  Say he is six feet tall and tell me, perspective and all, that there is more than 9 of him, wingtip to wingtip, across that airframe.  Forty eight to fifty four feet is not a seventy foot flying wing.


Couple this to known, major, modifications to the nose (which showed up in later GD employee pins of the flying wing configuration A/X, as the USN tried to bail as much tech out of ATA as they legally could...) concerning a 'stealth bra' and what we know of as the Advanced Tactical Aircraft is likely nothing more than an early RATSCAT pole model or perhaps a bit of a 3D concept art which was safe to show the select few Congressmen with SAR-C access.  In any case, the pile of rust and regret at the FWAM is not a jet capable of carrying X16 Mk.82 and X2 AIM-120, internally.  Indeed, the AMRAAMs I vaguely remember as being in the Anigrand kit were closer to 1/144th than anything.


That said, a good, possible, solution here, if it will fit, is the Aires F/A-18F cockpit as my impression of the Super Hornet cockpit was that it was a direct lift of the A-12 cockpit simulator, right down to the MFD orientations and numbers.  Don't know if Quinta or Red Fox do a 72nd F/A-18F in their range of 3D printed decals or not but you will at least need a pair of NACES seats as the kit ones look like deck chairs right off the patio sale at Walmart.  Again, be prepared for them to be overscale.  The ATA was _big_, the Anigrand kit, not so much.  Likely because it is based on the Ft. Worth mockup.


Aires 72nd F/A-18F



A-12 Cockpit Mockup


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Ha! I'm working on installing an Aires F/A-18F cockpit tub plus seats in my Anigrand model. I had to kink it in the middle though. I'm using small pieces of white plastic strip to position the tub in the hole that I dug in the Anigrand resin. Next I'll need a bunch of Apoxie / Miiliput to fill the cavities around the tub.


BTW: the photo nicely shows the air bubble pinholes in the recessed area around the cockpit. I filled the 200+ pinholes on the rest of the model, but since I did not know (do not know) what I would do with area under the canopy frame, I left them there.




Edited by Rob de Bie
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Excellent beginning, I don't envy you the amount of resin you had to Dremel out of the Anigrand.  If I was going to do it over, I would almost consider cutting to the leading edge and just splicing in sheet.  The problem is the inlets, which are molded in.


Wait until you get to the bottom and try to expand out the weapons bays to full size.  One of the doors is molded shut when it should be a piano hinge, attached to the main door.  The center divider for the weapons bay and MLG bulkhead is also shared and ends up being about .20 across.  You'll need to box it all in, separately.  Fortunately, I got the upper and lower wings together and this helped, a little, with rigidity.  But you're still going to need to build up everything, separately (I used the CMK landing gear bays from the F-14), including a pedestal in the upper wing, and then drop fit from the bottom.  If you get the pedestal right it will all line up with the lower curvature of the wing.  If not, you have a lopsided jet (ask me, I dare'ya...) which sits funny on it's gear.


Don't worry about the pinholes, I'm almost certain that the jet has the flaps and access panels reversed, top to bottom.  Get out the sander and grin maniacally as you think of someone you dislike.


Depending on whether you have the early or later kit, you also get a vacform canopy which doesn't fit the canopy cutout in the upper fuselage vs. a resin one which is dim and thick and doesn't fit the resin frame.  


It's a great kit when done, but it needs a lot of TLC.


If anybody has pics of the mockup main weapons bay interior: I'm still researching the palletized weapons bay raft which supposedly looked something like the B-57 weapons bay door in terms of individual station mounting of weapons but which extended downwards as the bay opened to keep the aerodynamic or RF seal on the airframe.  It must have been a very big void inside the airframe because it was intended to be able to fit a HARM and Harpoon, side by side.  You're talking about a 44 inch and a 36 inch wingspan per weapon, with a twelve inch clearance for things like door actuators.  Even if the missiles are staggered, longitudinally, that's an 8 foot wide weapons bay, X2.  Add another 2X2ft for the self defense bays and at least 3ftX2 for the MLG and a third of the airframe is now hollow.  The center fuselage is completely taken by the cockpit, nose gear, turbo-path and engines.  Where does the fuel go?  There is not enough room above the weapons bays if the raft (which shows up in drawings) is accurate.


How they planned to get an 1,100nm radius from that design I have no idea.  It may have to do with the 'fat vs. skinny wing'.  If so, I hope Model Collect is on the ball because that and the stealth bra amount to a major change in airframe shape.


A-12 'Weapons Pallet'


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Thanks for the great YouTube links. The first one offers plenty of inspiration for the cockpit of my model. And the way the canopy opens (lifts off and rotates) was a nice surprise. I may copy that on my model. BTW: I'm no longer trying to recreate the mockup or the design drawings, the model is too far off. I'm now building it as a 'what-if'.


Regarding the 70'3" wingspan: that equals 21.412 m, or 297 mm in 1/72 scale. The model is 293 mm. Close enough for me. The model's outer weapon bay is indeed too short for an AIM-120. An AIM-9L would fit though.


Regarding the dremeling, here's the pit that I dug:




As you can see, I hit the intake ducts that I labouriously created. It was a 'two steps forward, one step back' situation. The ducts are restored now.


Here's the canopy + frame that came with my kit:




I made a new integral vacformed part, using the kit pieces as the mold. It's slightly oversized now, compared to the kit parts.


I'm not quite sure whether I follow you with the main weapons bays. Are you saying they should be extended outboard until they touch the MLG bays? Here's what my model looked like:





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Really nice work there.  Keep it up, your successful completion will dictate the immediate release of a followon injected kit...;-\


A-12 Head On



Like a closet door or a piano cover, it's a bi-fold door panel setup to cover a very wide weapons bay.  The Anigrand bay is literally half that size.


Anigrand A-12



The F-22 features the same approach (to reducing ground clearance problems), as does the J-20, but their fuselage bellies are not nearly as sculpted underneath which tells me the A-12 bay doors may also be segmented, longitudinally.  Also, look at the bay door's relative position compared to the inlets, where the mockup door panels come almost halfway across the inlet.  Compare this to the funky dagger-facets of the kit bay which, again, indicate 'half a door' (and which would likely break off or distort due to Q-stress across the narrow base in real life).  Instead of those impossibly sharp points, it should look like this-


YT Mockup Bay Doors



Ironically, though nominally the same mockup, the presence of the second, folding panel, on the A-12 primary weapons bay doors is not obvious in the video but the shape of the door edge faceting is still markedly different from the kit versions while the weapons bay is butted up right next to the MLG bay.


To me, what is going on is the weapons bays are both kicked too far outboard from the centerline (they should be roughly aligned with the middle of the inlet openings) and come too far forward, relative to the necessary forward equipment bay space which would have been needed for the FLIR and Attack Radars while also not extending all the way out to the MLG bays.  As indeed they must because you are talking about two missiles, 40"X13' and 36"X12'.  Fintip to fintip, with the weapons bays never overlapping the very narrow intake/trunking volume that threads the needle between the inner bay walls and the cockpit module as an engine fan masking serpentine-


A-12 Planview Drawing



Now add the fact that the outboard bays are not 'AIM-9 only' but can literally house a fullspan AIM-120B (21"X12ft)-


A-12 FWAM Glamour Shot



AMRAAM B In Outboard Bay



And it becomes pretty obvious that the LE sweep is off and with it, the total chord length available to stuff appropriately large weapons bays into the available volume before the aft edge of the airfoil swoops upwards.  At this point, you need to ask how far you want to go to try and fix things because it is equally clear that the inlets are also severely distorted in the overly chunky nose-


Real Inlet



Real Inlet 2



Anigrand Inlet



Which again, to me, indicates the sweep angle of the leading edge is not high enough and thus the (spanwise) length and total capture area of the inlets is too small.


Yet, for what we are discussing, perhaps the best reference drawing is this one-


A-12 Lower Bays And Flaps Layout



As you can see, you basically have a void of open internal volume across the inner two thirds of the aircraft with only single structural frames dividing each of the various bays and supporting the longitudinal structural carry through while showing no spanwise (twist and torsional support) spars or fuel tank structure, at all.  IOW: A Tardis.


The A-12 was less a fraud than a strategic bluff to get the Soviets to 'buy in' on a tactical flying wing that is structurally an impossibility as presented, being unable to contain the relevant systems and fuel it would have needed to do the things it is said to have been capable of (SEROC and bring back radius with payload X).  Yet it is such a cool looking shape that it is deserving of /someone/ (Model Collect, are you listening?) finally doing it correctly.


Anigrand relied too much on 'concept art' propaganda and limited available views of the mockup.  And thus their replica is compromised, much like the early F-117 models were, by LE sweep vs. feature placement.  I personally believe that if the A-12's actual sweep angle were ever correctly portrayed, the resulting airframe size and MAC derived center of lift would intuitively make it questionable whether the wing could even come aboard.  As would the relative lack of power inherent to the ~12,000lbf F412s which supposedly powered it.  B-2 level, 17,000lbf, F118s would have had a hard time pushing the 75-85,000lbs of the 'full size' Avenger II off the deck.

Edited by YKM
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YKM, lots of good information and analysis again! I now understand the problem of the width of the main weapon bays, and their doors. But like I said before, I've giving up the idea to build an accurate replica of the actual design. It was way too much work already 🙂 I will change the inner sides of the inlet openings though, they never made aerodynamic sense to me, and maybe the modification will take away some of the chunkyness of the nose area.


BTW, the Anigrand model matches the LE sweep of the drawings you linked to, when I hold the model to the computer screen.




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12 hours ago, Rob de Bie said:

YKM, lots of good information and analysis again! I now understand the problem of the width of the main weapon bays, and their doors. But like I said before, I've giving up the idea to build an accurate replica of the actual design. It was way too much work already 🙂 I will change the inner sides of the inlet openings though, they never made aerodynamic sense to me, and maybe the modification will take away some of the chunkyness of the nose area.


BTW, the Anigrand model matches the LE sweep of the drawings you linked to, when I hold the model to the computer screen.




Good to know.  How about total chord length?


I wish you good luck on getting those inlets correct and hope you will also look carefully at the drawings as it appears that the A-12 had a rotating/translating inlet lip, similar to the-


20_2.jpg (500×639) (airforce.ru)


To further improve low speed mass flow.


Please post pictures when done.

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I measure 154.5 mm on the centerline, but maybe I need to round that off to 155 mm, because the nose could be worn down a bit from the extense handling and sanding operations. FS 447.08 from one of the drawings you linked to gives 157.7 mm in 1/72 scale. That makes the model 98.3% of the target value, for the span this number is 98.7%. Fairly consistent 🙂


Yeah, I spotted that moving lip too, and it answered a question that I long had: how does this intake geometry deal with large angles of attack? Now we know.



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I have never seen a single example of program era A-12 concept artwork with the (very fat, very deep) 'Leading Edge Flaps' deployed.  Have you?
The Closest I've ever come is this-
Which seems to be one of Flight Global's famous cutaways, post cancellation. 
I think this is because the concept of using an active 'stealth ribbon' which cancelled/ate radar returns at the airframe edge and which sent LMTAS into a panic of F-22 'One weekend the VP called us in and told us to clean sheet the aircraft...' 1986 redesign was, in fact, one of the things which Ben Rich introduced or adopted to a 'Level 2 airframe when it arrived in our shop' A-12 configuration that turned it into a 'Level 9 airframe when it left the RATSCAT'.
Everything prior to that is talking about an F-117 level RAM-as-applique which might well have been the VLO SOA for 1983-84 when the ATA program got going.  But which most assuredly was not compatible with the high shock, high galvanic corrosion threat of a marinized stealth operational environment.  
Which leads to the question of whether the A-12 or it's prototype testbeds were looking for an operational solution or pioneering technology for it's own sake.  Real world stealth vs. radar interactions goes beyond any possible Ufimtsyev scattering model's ability to predict on a computer.  But it helps if you can keep the FES elements limited in their planar reflection surface alignments and a flying wing testbed helps here.
What this could mean is that the actual intended airframe, testbed or service intended, didn't have a thick LE because, from later program outcomes, we know what they were testing for.  Indeed, contrary to reports, to me it looks like the A-12 was all about stealth investigation which was _solved for_, from the beginning, as a primary program design objective in selection of the configuration.  You certainly wouldn't make your life harder, in a carrier airframe, by removing the tails 'just because'.
This investigtion continued to the point where the weight crisis issues of packaging were considered secondary as an exact reversal of the stated history.
The airframe is so clean of vertical plane interactions that a Cold Pigeon or Sneaky Pete level X-plane prototype could fully exploit the RF signal characterization of the radar waves as they impinge on the airframe using dedicated signal measuring hardware/telemetry buried throughout the thick sectional depth.
That's important.  You are not trying to design the airframe around how the structure and surfaces interact with the radar wave like a sea wall stopping a breaker.  You are trying to define how to the radar waves flow and move over the impedance loaded airframe, using different material/surface quality junctions.  It is this signal characterization effect which drives the massive, continued, investment in the ASQ-239 Barracuda which has ELS quality (inch by foot, long/short baseline signal characterization) in a jet which has no ARM to shoot.
Understanding the surface wave not the target shaping is in turn what makes stealth on the largely conventional, cruciform, F-35 possible.  It also explains the obsession over tactical data files and how the USAF is not too worried about foreign technology loss of stealth.  Because an active cancellation system is software driven and while 'day to day', the U.S. service F-35s may have the same LO values as an export model, GTW, someone flips a switch and it's not the same jet at all (why the F-35 is both 'inferior and superior' to the designed for high-end passive stealth F-22).
Now we have at least a starting posit for the real reason that Five Billion in wasted money was invested.  Because, like the Have Blue program, the construction of prototypes was largely conventional, rapid and on the cheap.
Flybywire and CATIA made it so, even in the 80s.
The fabrication of structually compatible materials (what would become 'fiber mat') in an RF sealed composite stack was what was going to take awhile and cost enormously, ultimately coming to challenge the scaling and airframe weight issues in a way that would destroy the program's viability for a carrier boarding, operationally suitable, jet.
So, let's talk about some A-12 program history.
First, get this book-
Eat Ramen for a month, take out a second mortgage, sell a kid into bondage, whatever.  If you are interested in the A-12, it's a necessary part of your book case.  'The story' (Legend building) is that of a lawyer trying to talk economics, lost in Merlin's magic room of Aerospace, as the sounds of Fantasia arise in the  background.  He doesn't know aerodynamics.  He doesn't really know RF.  But there are moments when the potent quotables he includes to pump up his dialectic prose do hit home.
One is of a 'Chicago Christmas Party' (Hookers, Blow, Communism as a liveable fraud, you know...the holidays) in the late 80s whereby an inebriated Admiral, upon hearing from a reporter that word was going around that the A-12 was going to cost 140 million dollars and weigh more than 75,000lbs, responded (as dead serious, sour puss, admirals are wont to do) 'I'm sorry, I have no idea what you're talking about, excuse me.'
Oh, no, wait, that's right, what he /actually/ said was: "The A-12 will cost 35 million each and weigh less than 50,000lbs or it will never come aboard a carrier, we cannot afford to wreck the airwing acquisition for stealth because we also have to pay for a floating runway and some battlegroup escorts.  You must be wrong son."
Which the reporter promptly shortened to 'USN Admiral says the Navy will never buy the A-12!' for his Tribune headline the next day.  He never said who told him the rumor, but I would imagine that the entire defense establishment watchdog agencies (CBO/CRS/GAO) knew what was going on.  Because they have experts too.
The other interesting thing, buried in the indices, is a mention that the reason the Navy and ultimately DOD could not hold GD/MDD responsible for A-12 progress shortfalls was because there had, in fact, been progress.  Serious progress.  Centered on stealth.  Not weight.
And of course Big Daddy Long Pants USG was uber-reluctant to have this brought up because they were using an accountant to define the expenditures outgoing vs. the goal post markers passing under the wing.  And that accountant was not cleared into the compartment which dealt with the very real LO engineering which had been the primary, not secondary, program goal.  Mention is specifically made of a 'stealth bra' which specifically fixed the nose RCS issues of the jet.
What does a brassiere do?  It resets the thrust line of the bust to make it lift higher, jut further and look more full.  In this case it made the viciously poor planform alignment of the intakes  with a buried turbopath and 'inlet blockers' (ala B-1B retro-reflectors) into a more competently designed, lateralized and larger, mass capture area which could accept a horizontal instead of a vertical serpentine while providing for a much higher installed thrust from (period) PW7000 level engines in the 16-20,000lb IRT thrust range, similar to the later GE F414.
Again, an accountant is not going to know or understand this and the USG definitely did not want it in even a sealed judicial record but the judge clearly did get the gist, because GD/MDD won case after case of 'Nuh Unnh!' lawfare and endless government judicial forum shopping appeal on the basis that the companies were indeed _doing the work_.
They simply could not productionize it because the USN had completely dropped the ball on the 'get the weight out and we'll get you the stealth tech access!' nominally false promises (truth: I believe neither LMTAS nor Northrop had the technology base to bring navalized LO to the fleet either and the ATA effort was largely about third generation stealth development beyond anything being discussed for the F-117 -or- B-2A, the ATF redesign being perhaps the first indication of where this was going and the F-35 defining the outcome...). 
Sigh.  Okay, so let's talk about the A-11/B-2 Minime alternative design by Northrop which, when the Navy laughed at the projected 'best effort' costs, Tom Jones laughed right back, picked up his engineer dollies and walked out of the ATA contract negotiations.  
Note how long that jet is.  Almost a hopeless diamond with wings kind of geometry (albeit one with terrible carry through for the 'folding/flapping' outboard panels.  This will be important for later in the A/FX reference...).
If you believe in the USAF approach to a stealthy, high-flying, penetrator where standoff is built in by sensor slant, the 'define the wave to design the jet' part of the electrical engineering exercise means you only have to worry about RF from the lower hemisphere.  Which Northrop knew because they were leading the ATB (B-2) effort.
On the A-11, this meant you could have a thin leading edge.  And from the thin LE, you can have a much better structural density at the centerline rather than a spanwise loading concept because there are bumps in the middle, accounting for engine turbopaths and cockpit/weapons bay modules as being above rather than buried within the fuselage, thereby allowing for a much more conventional spanwise spar+stringer structural emplacement as fuel tank holdings.  
That's not possible for a carrier jet which wanted, originally, to put X24 Mk.82 inside the fuselage (the USN 'settled' for X16), have a sub-1m RCS from all aspects _and elevations_ (allowing for low level penetration) and generate a 600nm radius with useful bringback of high end guided weapons for a carrier suitable vertical landing acceleration of 30fps.  All while allowing for the fact that the wings had to fold and the engines be removed, shadow of the airframe.
The stealth is still the big dog driver here as the ability to put a circuit grid, 'fiber mat', layer beneath the dielectric composite stack demands really thick skins overall and so you end up with a big, fat, blended-wing-body wing and high taper to avoid adverse aerodynamics (TRO, buffeting, drag rise etc.) in an airfraame that develops the chunky look of a slung brick.
And the Navy knew all of this, because Building 512 (Navair R&D) has a massive database of all prior airframe programs which they use to honesty-check contractors buy-in to the costs and capability promises of any design they are looking to put under contract to develop.
Indeed, one of the only people to go to prison over this was a female lawyer, not an aerospace engineer, not an EE, not a naval officer with no defense acquisition school degree, but a /lawyer/ who supposedly told the Navair Admirals to ignore a burgeoning, '2,500lb', weight overage.  And instead use it as an arm twist to get better deals out of the contractors, later on in the production and contract support phase.
Which sounds fine and inline with the Legend of program-wide gross ineptitude except that this is the 1980s and so women are still kept out of the upper echelon of most industrial and government services decision making; a USN Admiral would never listen to a Lawyer when it comes to aviation architecture issues outside her wheelhouse; and a lawyer would never risk disbarment and potentially serious prison time (two years per count) selling fraud in the inducement phase as a potential for Deficiency Act violations in the very acquisition field she -was- a specialist in.
So it's all a lie.  A grotesque and crude coverup.  A Legend.
Once you realize that the government only ever lies, it becomes easy to see the truth as the literal opposite to anything they say.  Now we just need to reverse engineer away from the lies to what really happened.  Maybe.
It's all about Scaling and Size.
First off, I am grudgingly willing to accept that an 296 X 156mm Anigrand A-12 is factually a 1/72nd representation of a 70ftX37ft flying wing for sweep and dimensions.
I still think there are other issues inherent to a 'stealth bra' which in fact radically redesigned the forward fuselage and thus had to have effected LE sweep.  And in a 'fat vs. thin wing' which equally reallocated internal volume and CG disbursement of available weight.  
Because, while nominally still the same mockup, this-
Is not this-
Nor certainly this-
Which I believe is the 'production A-12' (later known as A/FX when the Navy tried, desperately, to recover the tech base of the ATA program).
Note how much the bra elongates and smooths the LE transitions.  Note the thickness of the wing LE which can now have a folding LEF vs. a translating slat.  Note the size of the inlets and the fact that you can actually believe they are not cutting a 10" deep gash in the lower forward fuselage, simply to fit rotating/translating massflow door with METAL ACTUATORS just below the skin.
The A-12 mockup is in fact something more akin to this-
A cartoon.  A caricature.
And once I knew that, I started thinking about where I had seen similar visual prevaricative illusion.  And of course I came to this-
https://yf-23.webs.com/Pics/ATF/Lockheed/Lockheed ATF impression 1A 623.jpg
As the 'ATF' configuration which is effectively the upper half of a very deep, chunky, (stealth costs volume for planar alignment and composite stacking people) F-22 fuselage.  And which makes the concept art look all swoopy-cool, evoking an emotional rather than analytical based (never fit an 800nm radius, eight missiles and supercruise turbopath in that space) response to a fantastical outline.
Okay, so what makes the A-12 look like what it does, when it's such a plain shape and you hardly ever see internal images of the bays and so on.
Of course it's the canopy.
What if I told you that this-
Is not this-
As one of the few, fully unshadowed/perspective shifted images of even concept art from the program?
So let's look at the canopy as the sole scaling feature on the otherwise vanilla airframe.
Does it help if I put a person in, for scale?
Does it help if I remind you of that 'A-12 canopy' which was up for auction on EBay, awhile back?  What, did they have a spare?  For a mockup?  The above illustrate a canopy that is not nearly as large as the mockup makes it out to be.
Okay, then let's take the scaling/proportionality thing a little farther-
That is a seventy foot wingspan A-12 set against a 64ft wingspan F-14 for deckspotting purposes.
Now add ten feet to the chord length so that it's a fifty foot wing chord instead of thirty seven.  While maintaining proportionality of the shape.  And suddenly it's an 80ft flying wing.  The wingsweep doesn't change but proportionally, the airframe gets a heckuva lot visual-area bigger in overall planform.
Now your canopy scalar reference changes and the A-12 is not an Aliens Xenomorph bobble headed freak.  It's a pinheaded giant with a low profile race car windscreen on a monster of an airframe.  An airframe so wide of wingspan that it likely could not launch, side by side, with another Avenger (or anything else) on an adjacent catapult.
That last especially is indicative because it _is_ a perspective alterred (crossing at an angle to the 'camera'), shadowed, image of an 80-85ft wing with a tiny relative canopy size.  And lateralized big-inlets sized for a much larger engine.
It is the 'FSD/pre-production' A-12.  Not a subscale bit of 3D concept artwork.  And it is pre-production because it still has not solved the inlet stealth issue.
The more I think about it, the more it really does all come down to the thrust loading and stealth of the turbopath and another (paraphrased) quote from Ben Rich in the above A-12 book:  'You gotta design a stealth engine exhaust to cook to higher temps, after it shuts down, until natural convection/conduction can carry away the heat.  If you don't, you'll destroy all the stealth coatings...'.  To which I will add that you will also generate a large surface hotspot to IRST, in lookdown, as the engines literally 'glow', through the airframe.  That bypass duct is almost certainly delivering cool air to the engine/exhaust bays, possibly even after shutdown.
Now, let's look at the A-12 engineering drawings once more-
Do you see that secondary bypass duct?  Do you see the way the serpentine is vertical with a small slope/hump, like the X-32 or F/A-18E, rather than being horizontal, like the F-22?
Here's another view-
See how small that horizontal kink is in the clear-view model?  It's very nearly a straight path.
That's why the wing LE looks like a slope sided brick.  The stealth displacement of the turbopath into the vertical axis is driving a very deep 'fuselage'.  And the very deep fuselage with next to no structural web, is quite heavy because you are literally casting a geodetic frame, like a Wellington bomber, INTO the skins.  So that fuel tanks can fit under them, above the weapons/gear/self defense bays.  As the only remaining volumetric option.
And again, from the book-  'The outermoldline was designed separately from the inner frame.  We literally built the airframe backwards, like an exoskeleton.  As such, we found that it was impossible to get integral frames to cast correctly because their thickness meant they had differential curing in the autoclave and so shrank during cool down, causing microcracks, especially around fastener holes...'
Again: the airframe IS the structure.  It is the equivalent of stressed skinning in a conventional, aluminum, jet.  And it failed because thermoset composites do not cure strong enough and thermoplastics (if they were even available back then) are too unreliable in their cook out/shrinkage and would remain so, throughout the 1990s (See: X-32).
Further to which, I doubt if the vertical engine serpentine was enough to protect the engine fan faces.  The 'RCS vanes' almost certainly impeded mass flow delivery and probably generated their own returns rather than suppressing random aspect/band flash-back from the engines (because they do on the B-1B too).
While the overall planform geometry control of the inlets is _awful_, creating rather than stopping multipath returns from the fat lips which are also going to spill (no boundary control) sticky turbulence down their throats.
When your deck spotting requirement means you have a restricted moldline size to work with, you end up with a combination of structural carrythru issues, contradictory stealth requirements and volumetric packaging problems in what is already an overly optimistic weapons system/mission payload airframe size requirement (two of everything + 10,000lbs internal weapons...).
And those fixed specs mean your overweight airframe has all conventional engineering tradeoff tricks blocked by the configurational demands.  Irony of ironies, the A-12 program is oft criticized for never generating a COEA/MENS/JORD based requirements document before beginning development when, in fact, the important specs were too tight, not too loose.
Supposedly, the Navy wanted it all.  On a shoestring.  But using their own database, pursuing it, especially in an entirely new airframe design, should have been seen as a surefire recipe for disaster.
All of which leads to a jet which not only cannot achieve hi-hi-hi level 'USAF profile' stealth penetration performance (VLO in the trashfire band) but has serious issues with SEROC and sink rates, around the boat.  Which is an absolute no-go for an operationally suitable naval strike platform.
Conversely, if you blow out the moldline by 10-15% but keep most of the design elements intact, the very nature of a bigger-by-area flying wing means you get better internal packaging for a return to a conventional structural layout (The F-35 is a conventional, aluminum airframe, design, integral composite structures did not work out), resulting in better lift, more thrust potential and potentially better stealth through a larger, redesigned, inlet and T-path.  But your weight reserve is completely gone as the cat limits on longitudinal NLG acceleration simply cannot be argued with.  The  butt-breaking F-35C vertical endloads have already proven why this is.
So, instead you split the diffference, by half-spans. The inner wing retains a long-chord depth to accomodate a laterally displaced intake curveature which tightly folds around the cockpit module to the centerline engine bays to provide a full on serpentine within the added chord length.  The maintenance nightmare inlet vanes go away, as does the need for lip doors in the bigger inlets, while the geometry of the intake is reprofiled to allow for the inlet walls to cant sideways (both inner and outer), meaning the oblique, vertical, RCS return pathway is always angled away from the source emitter.
The inlet trunking may still have a large bypass channel to mask heat from the buried engines and provide a cooled exhaust plenum but it could also be using fuel for exhaust tile evaporative cooling as the F-117 coanda slit does.  A single unit intake path likely reflects an increase in massflow delivery to the engine that, in turn, is reflected in higher sea level cruise, better single engine rate of climb, radius over 1,100nm and a _higher ceiling_ of a larger, 'no fat', wing (all reported in the Stevenson book).
The latter could equate to a different (no look down protection requirement) take on signatures in general.  As a further weight savings.
One which leads to a theoretical fueled weight reduction deriving from the combination of lower throttle settings on a high massflow, more powerful, engine core, cruising in a low drag, high altitude, regime.
The reduced span outboard changes the center of lift and allows an RSS airframe to teeter, between the cockpit/NLG forward and the engines/exhaust further aft as primary CG effectors while continuing to cluster weapons bay stations around the MAC so there is no controllability issues in a naval sink rate condition with bringback stores.  The straight trailing edge is not ideal for stealth but likely incorporates a rear spar for added rigidness.
A lower sweep outboard panel also maintains an appropriate low speed, powered lift, curve with spoilers controlling sink rate and auto-throttle driving glideslope and scatter as is the preferred norm (Delta Path/JPALS) with present navy jets.  And something which could never happen with the underpowered F412 version of the ATA because there were simply not enough donkeys pushing the cart.
I doubt if we were ever intended to see the A-12 as the A-6 replacement success story it could have been.
Probably because the spoiled Navy brats wanted a new fast-jet toy like the F-22 to play with and when they could not get their own, they were willing to screw up, not just Navair but destroy the entire military industrial aerospace base (GD and MDD were the top two fighter houses in America, not Lockheed or Northrop) to force a tacair acquisition train wreck in which they got both the F/A-18E and F-35C as placeholders, and now are positioned to get NGAD.  While the F-22 acquisition was ended at less than a quarter of the desired airframe inventory.
When lies become the norm of any process to 'protect the truth', the purpose of the process is inevitably corrupted to the point of dysfunction in it's original intent to defend the nation, ablely.
If we are lucky, NGAD/PCA will look like a supersonic flying wing (60' sweep) in which the principle systems modules are rafted atop (cockpit, engines) and underneath (weapons, gear) the wing carrythrough to generate inverse ruling in a huge fuel fraction (.35-.39) platform and the structural technologies and stealth which the A-12 program pioneered finally will find a genuine, ultimate, expression.  Whether or not such a fighter can board without signature crushing VG is another matter.
If we are very fortunate indeed, we may be able to afford two such jets, so that the spoiled siblings of the rival flying services don't have to share just the one, on an every other war basis.
From this perspective, 'Misunderstanding' the application of five billlion dollars on a failed stealth-systems R&D effort, in the wake of the 426 billion thrown away on the F-35 (literally, 350% more than the original 120 billion planned) is no big thing.  I mean, if you're going to actively defile Nunn McCurdy at that scale, what's a little slap and tickle in the black world closet beforehand?
But sending two of your competitive-bid aerospace contractors out of the defense sector entirely is what will drive costs on the remaining Big Two fighter houses.  Because LM and Northrop Grumman know there are now no alternatives.

Edited by YKM
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On 12/14/2021 at 3:54 PM, YKM said:

I have never seen a single example of program era A-12 concept artwork with the (very fat, very deep) 'Leading Edge slats' deployed.  Have you?
The Closest I've ever come is this-
Which seems to be one of Flight Global's famous cutaways, post cancellation.


No, I've never seen deployed slats. And if I may launch a wild speculation: maybe there were vortex flaps like the X-32 had? Kasper wing style? Probably not..


YKM, I'm learning from your extensive posts, please don't stop posting.




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In the mean time I changed the inlet geometry from this:




To this, using five spring steel wires to define the edges, so I putty and sand without losing the sharp (but rounded) edges. Next is more Apoxie Sculpt and then paint to see what I've done - with four colors you just can't that.




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Absolutely outstanding.  That took some real guts, I would not have had the courage to use wire there (CA and metal always corrodes and chips out for me) but it looks like you pulled it off.  Really looking forward to seeing it under some primer so I can see how well you've done capturing the under cockpit area.


Did you make a template of your 'best side' with some card or sheet stock to guarantee symmetry?  I say this because, well, Anigrand.


Also, are you going to do anything to capture the sensor windows for the FLIR and so on?  It wouldn't take much more than a chiseled out area, black painted with a tinted clear sheet stock laid in over the top to make it happen.


Either way, it's coming along nicely, please continue to send updates.  Hope you're having a great weekend.

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I like to use templates, but the shape is too complex (for me) to make templates. I'm doing it by eye. I hope to paint it tomorrow.


The sensor windows in the leading edge were quite a mystery to me, so far. But with the drawings that you posted I now understand what Anigrand tried to portray there. I will probably tackle that too. But it could take some time - my build log tells me I bought and started this kit in 2005 🙂



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