General Dynamics ATS, pre-ATF and ATF designs

[icyplanetnhc (Steve)]

The F-22's wing is a modified delta. A delta wing basically means it has a triangular shape in planform, it's just the trailing edge is slightly swept forward on the F-22. It doesn't have anything to do with whether or not the aircraft has a horizontal tail. The MiG-21 is one of the most famous delta winged aircraft around and it had a horizontal tail. But, I understand that most people think of tailless designs when they think of delta wings.

Right, the F-22 wing planform and aspect ratio aligns pretty well with a delta wing, I was simply highlighting the similarities between the GD ATF and the F-22 after the summer 1987 “fire drill” which saw the configuration change from swept trapezoidal wings to diamond-like delta.

Massively as the various materials (e.g. CodeOne magazine) make clear.

Well not necessarily; reading the article from Code One as well as Sherm Mullin’s account, a variety of configurations were explored when the swept trapezoidal wing design became untenable due to weight. The articles didn’t explicitly state that the chosen configuration was based on GD’s proposal, only that substantial weight savings while maintaining roughly comparable aerodynamics to the trapezoidal wings was the driving factor. That said, I wouldn’t be surprised if it did use a lot of work from GD’s submission.

 

[overscan (PaulMM)]

Sherm's account emphasizes how much of a team effort it was, so trying to isolate specific features to specific companies might be fruitless.

 

[helmutkohl]

a question about the tail..
I think it was mentioned earlier that GD had some issues with the single tail.. were there any other alternative designs for the tail or planform?

 

[overscan (PaulMM)]

a question about the tail..
I think it was mentioned earlier that GD had some issues with the single tail.. were there any other alternative designs for the tail or planform?

Yes there's lots of wind tunnel models where they tried lots of different things with the tail.

 

[red admiral]

Sherm's account emphasizes how much of a team effort it was, so trying to isolate specific features to specific companies might be fruitless.

Very much. It seemed like the team worked very well and it was very much a combined effort.

 

[overscan (PaulMM)]

Moved posts to correct topic for General Dynamics ATF projects - original topic was a user artwork topic.

 

[icyplanetnhc (Steve)]

Oh the subject of the difficulties that GD had with twin vertical stabilizers in their ATF proposal, the F-22 would also end up encountering problems with vibrations and buffeting in the vertical tails at certain Mach numbers and g conditions, due to the vortex impingement at those specific conditions. This was reported back in 2000.

https://www.flightglobal.com/buffeting-problem-may-mean-airframe-changes-for-f-22-/34405.article
According to Jay Miller’s book on the F-22, this issue was eventually resolved with some strengthening of the vertical tails and flight control software changes.

Still, this makes me a bit curious on why GD abandoned twin canted vertical stabilizers. Perhaps there wasn’t enough time for them to fine-tune a satisfactory configuration before the RFP submission? Along with the inlet, vertical tails took among the longest time in wind tunnel testing for the Lockheed/Boeing/General Dynamics team, and even then, there ended up being buffeting from flow impingement that modeling had failed to predict.

 

[Orionblamblam]

From 1977. Probably a bit early for this thread, but the technology would prove important to ATF...

 

[TomS]

From 1977. Probably a bit early for this thread, but the technology would prove important to ATF...

View attachment 675232
View attachment 675233

The design 2nd down on the left reminds me a lot of the bottom image here:

https://www.secretprojects.co.uk/th...s-ats-pre-atf-and-atf-designs.416/#post-55335

 

[overscan (PaulMM)]

That's pretty awesome, Scott. ATS is the same kind of timeframe, so not off-topic.

 

[Sundog]

I have an old Air Combat magazine with the design shown at the top of page 21 in it. I remember trying to model it out of sheets of basswood when I was a teenager.

 

[rooster]

General Dynamics 1986 Supportable Fighter study (Configuration 700)

What a cool fighter I've never heard of

 

[flateric]

Some very familiar planforms

 

[Sferrin]

From 1977. Probably a bit early for this thread, but the technology would prove important to ATF...

View attachment 675232
View attachment 675233

Interesting similarities to this Fairchild concept from around the same time.

 

[alostbaron]

Some very familiar planforms

Do we know the model number for the aircraft at the very bottom right?

 

[quellish]

Do we know the model number for the aircraft at the very bottom right?

https://www.secretprojects.co.uk/th...igeon-sneaky-pete-have-key.12448/#post-203848

 

[icyplanetnhc (Steve)]

Looking at the General Dynamics ATF again, was there ever a rationale given for the "messy" trailing wedge shaping? While the angles would match the leading edge, having this many edge discontinuities seems to be even worse.

 

[flateric]

Worse compared to what? Apparently edge alignment was a major moving factor here.

 

[overscan (PaulMM)]

Moved to correct topic.

I think this diagram gives a hint:

The central thrust of General Dynamics ATF development prior to the "stealth reset" was a tailless delta. I imagine the 'serrated' edge approach was to align the trailing edge to the leading edges for decreased RCS reasons without departing too greatly from the existing wing geometry.

 

[robunos]

Moved to correct topic.

I think this diagram gives a hint:

The central thrust of General Dynamics ATF development prior to the "stealth reset" was a tailless delta. I imagine the 'serrated' edge approach was to align the trailing edge to the leading edges for decreased RCS reasons without departing too greatly from the existing wing geometry.

Drifting off topic, but would this approach have worked with the GD / MDD A-12 ?

cheers,
Robin.

 

[Manuducati]

Drifting off topic, but would this approach have worked with the GD / MDD A-12 ?

cheers,
Robin.

Congrats, now you have the Northrop/Grumman/LTV ATA submission.

 

[robunos]

Congrats, now you have the Northrop/Grumman/LTV ATA submission.

I meant with smaller serrations, more like this . . .
(rough sketch only . . .)

 

[icyplanetnhc (Steve)]

Worse compared to what? Apparently edge alignment was a major moving factor here.

I get that the numerous serrations were meant to align the trailing edge with the leading edge, but with so many discontinuities, I wonder if it would have been better if the trailing edge was just straight and at a less swept angle that doesn't match the leading edge (not perpendicular to the front, obviously).

However, based on the chart that overscan posted, it appears that a straight trailing edge had been considered but was dropped in favor of the serrated one. However, neither Lockheed's nor Boeing's submissions used this approach, and in the end the F-22 didn't either and went with a trailing edge that was at a less swept angle, although that could also be due to the integration of horizontal tails.

 

[aim9xray]

Goes back to requirements, requirements, requirements. And then tradeoffs. And edumacating the customer where needed. And where politically possible.

 

[alostbaron]

Source:
http://www.militaryphotos.net/forums/showthread.php?166065-YF-23-Black-Widow-II-pictures/page8

[Correction: pictures below are taken from Jay Miller's F-22 Raptor Aerofax book. This is a "must buy" for anyone interested in the F-22. - Admin]

I notice that atf8 image seems to indicate that the lerx are posable, like the Su-57. All the other surfaces like the slats, ailerons, flaps, are outlined as well. Am I looking too deep into it?

 

[flateric]

LEVCONs you mean. Yes.

 

[alostbaron]

LEVCONs you mean. Yes.

My apologies, I meant levcons yes.

 

[fightingirish]

An artist's conception of the General Dynamics proposal for the Advanced Tactical Fighter (ATF) competition in response to USAF Request For Information (RFI) in 1981.
Source:
https://catalog.archives.gov/id/6415287

 

[donnage99]

I notice that atf8 image seems to indicate that the lerx are posable, like the Su-57. All the other surfaces like the slats, ailerons, flaps, are outlined as well. Am I looking too deep into it?

those places are where the radars go instead of the nose

 

[allysonca]

Found in a local estate sale from a General Dynamics exec, these models are head scratches to be sure. Anyone have design numbers to assign to these oddities. I am fixing them up and these are in the primer and sand stage as you can see and trying to decide how to paint them......if I should. Maybe grey and just a canopy methinks.

 

[Sundog]

Found in a local estate sale from a General Dynamics exec, these models are head scratches to be sure. Anyone have design numbers to assign to these oddities. I am fixing them up and these are in the primer and sand stage as you can see and trying to decide how to paint them......if I should. Maybe grey and just a canopy methinks.

This is what happens when you let the kids use the design software on "bring your kids to work," day. I'm still trying to figure out the large over wing inlets and small v-tail. The tail would be completely blanked out at moderate alpha and "Why such large inlets?" They are definitely interesting, to say the least. Thanks for sharing.

 

[SMGC]

Found in a local estate sale from a General Dynamics exec, these models are head scratches to be sure. Anyone have design numbers to assign to these oddities. I am fixing them up and these are in the primer and sand stage as you can see and trying to decide how to paint them......if I should. Maybe grey and just a canopy methinks.

Is the estate sale still ongoing or from some time ago?

 

[overscan (PaulMM)]

Presumably overwing engine intakes but they look outside. e.g. approx double the size of this Rockwell/McDonnell Douglas AX - A/FX

Or the A/F-117X


Vought VMX

 

[overscan (PaulMM)]

This one seems to be an F-16 kitbash burdened with a large intake, twin engines and cruciform tail surfaces.

 

[icyplanetnhc (Steve)]

This is what happens when you let the kids use the design software on "bring your kids to work," day. I'm still trying to figure out the large over wing inlets and small v-tail. The tail would be completely blanked out at moderate alpha and "Why such large inlets?" They are definitely interesting, to say the least. Thanks for sharing.

Or, given its current state, “bring your AI to work” day and let it go nuts on the CAD and 3D printer.

 

[overscan (PaulMM)]

They could be joke items.

 

[martinbayer]

I meant with smaller serrations, more like this . . .
(rough sketch only . . .)View attachment 718067

Which, as a retired aerospace engineer coming decidedly from the space side of things, for the simple reason of symmetry, makes me wonder whether a serrated leading edge might have had any potential stealth advantages as well? Please feel free to educate/excoriate me.

 

[overscan (PaulMM)]

Which, as a retired aerospace engineer coming decidedly from the space side of things, for the simple reason of symmetry, makes me wonder whether a serrated leading edge might have had any potential stealth advantages as well? Please feel free to educate/excoriate me.

For VLO, no. You want the edges to be as long as possible with no discontinuities. The B-21 shape is pretty optimal in the regard. I also think a serrated leading edge would be very "interesting" aerodynamically and structurally.

 

[overscan (PaulMM)]

I haven't found anything useful on these, @allysonca. Really mysterious. Could you share the executive's name?

 

[flateric]

Found in a local estate sale from a General Dynamics exec, these models are head scratches to be sure. Anyone have design numbers to assign to these oddities. I am fixing them up and these are in the primer and sand stage as you can see and trying to decide how to paint them......if I should. Maybe grey and just a canopy methinks.

Eventually this comes into mind at once...