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Author Topic: Northrop/McDonnell Douglas YF-23 and EMD F-23  (Read 478121 times)

Offline Sundog

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #1050 on: November 06, 2016, 09:42:05 am »
The USAF's MOA to acquire the A-12 speaks more for the soundness of the design and the validity of its CONOPS than stray remarks
from corporate competitors.  Listening to Rich, every competition that Lockheed won was on the merits and every competition they lost was
due to politics.

The A-12 was a political choice by the USAF to get the ATF built, just as the USN agreeing to get a variant of the ATF was so they could get the A-12.

Much like accepting the F-4 and A-7 was a political choice the Air Force made to get F-X.
Both happened to be superior to anything the Air Force had in the inventory for more than decade.
That's the point you seem unable to grasp. Whatever the shortfalls with the A-12 it would have been
superior to the A-6, the F-14, the F-111 and the "interim" F-15E. And there's still that gap in the US inventory.

Quote
GD had trouble with the heat build up

Gasp! An LO design that was thermally challenged? You meet like the B-2, the F-35 and the F-22 which I'm sure you'll
claim Rich engineered. Obviously, Rich is severely overrated as a thermodynamicist. 

Or it's just a recurring challenge that these programs have to confront and overcome. 

In reality, Rich hadn't engineered anything in 15 years by the time A-12 came around.
Do some research on how quickly your technical skills atrophy as a manager and VP.
 
Rich ended up as an engineering consultant. And like all consultants there's one overriding motivation: billable hours.
And the inevitable: "if only they had listened to me" when a project doesn't work. 

As for Northrop not bidding, they had no engineering resources to spare with B-2, YF-23 and TSSAM.
There was intensive competition for engineering talent in the late 80's which means skyrocketing
wages which is kryptonite to a fixed-price EMD contract.

As an aero-engineer, I know about the skills and what has atrophied over time, but it isn't difficult to get back in the groove if you know what you're doing. The simple fact, that you refuse to acknowledge, which is actually based on physics, not opinion, is the A-12 was a poor LO design. Could engineering have fixed it? Yes, it's called a new design.

Offline sferrin

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #1051 on: November 06, 2016, 09:59:27 am »
I wonder how things might have played out if they'd chosen Northrop's ATA design.
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Offline PaulMM (Overscan)

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #1052 on: November 06, 2016, 11:52:53 am »
I wonder how things might have played out if they'd chosen Northrop's ATA design.

Northrop declined to bid, so its not like they "lost" this, they walked away. I think Northrop had hands full on B-2 at the time.
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Offline DrRansom

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #1053 on: November 06, 2016, 12:52:07 pm »
Wait, the A-12 did not have aligned trailing edges, that would give it a much worse radar signature for basically no reason.

Unlike the Pak-FA, you'd get low signature with a performance impact.

Offline Steven

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #1054 on: November 06, 2016, 04:47:33 pm »
I think I've read that the A-12's straight trailing edge gave a substantial RCS spike directly front due to surface diffraction and creeping wave returns. It's one of those lower order phenomena that was not carefully considered. Honestly I don't think the problem could've been adequately addressed without a complete redo of the basic wing configuration.
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Offline PaulMM (Overscan)

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #1055 on: November 06, 2016, 05:54:59 pm »
I believe General Dynamics thought the spike to the rear was acceptable within the mission requirements, without realising the corresponding spike forward would exist. Dan Raymer at Rockwell hit the same issue with his Delta Spanloader design, and was told "yeah, that always happens, we don't know why" by the RCS experts there.
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Offline marauder2048

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #1056 on: November 07, 2016, 12:41:37 pm »
As an aero-engineer, I know about the skills and what has atrophied over time, but it isn't difficult to get back in the groove if you know what you're doing. The simple fact, that you refuse to acknowledge, which is actually based on physics, not opinion, is the A-12 was a poor LO design. Could engineering have fixed it? Yes, it's called a new design.

Fortunately, we don't have consider your background or weigh your opinion because:

The A-12 is one of the best documented cancelled SAPs of all time thanks to its long litigation history which has resulted in a huge ream of program documents in the public domain.

And nowhere in those documents which are contemporaneous, official records that were formally admitted into evidence and whose veracity was established
by the sworn testimony of those who prepared them do we find any proof for:

1. Thermal management deficiencies
2. Signature deficiencies
3. Survivability deficiencies

On the contrary, we have the Navy's chief engineers, DAB, JROC and independent consultants all attesting to the soundness of the design, the CONOPS and the requirements.
The Navy had in fact relaxed the weight requirements which it had acknowledged were too aggressive.  Even with GD/MD's weight growth the documents imply it was still lighter than NG's design. 

And nowhere in the court documents (unless I've missed it) do we have Rich's claims implied, statrf or corroborated despite the fact it would have been an explosive bit of evidence.
So the conclusion has to be that even if Rich is totally correct his assessment was not regarded as materially relevant since neither side entered it as evidence.

There's also no hint anywhere of a re-design being desirable or necessary to meet the reqs. 

« Last Edit: November 07, 2016, 12:51:28 pm by marauder2048 »

Offline Steven

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #1057 on: November 07, 2016, 01:43:37 pm »
The Navy's signature requirement for the ATA may not have been that aggressive in the first place. Not only that, the Northrop/Grumman/Vought team didn't actually submit a bid, so MDD/GD team speculating on the merits of their design compared to their competitors is about as valid as Boeing's protest of Northrop Grumman's win in the LRS-B.
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Offline sublight is back

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #1058 on: November 07, 2016, 02:45:34 pm »

And nowhere in those documents which are contemporaneous, official records that were formally admitted into evidence and whose veracity was established by the sworn testimony of those who prepared them do we find any proof for:

1. Thermal management deficiencies
2. Signature deficiencies
3. Survivability deficiencies

Well of course they didn't testify to that. You think they wanted to pay the Navy back for the gross mismanagement that drove the program into the ground?

Offline flateric

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #1059 on: November 07, 2016, 04:16:57 pm »
"There are many disbelievers in
stealth, more than a few of them truly technically ignorant and proud of it." Sherm Mullin, Skunk Works

Offline Sundog

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #1060 on: November 07, 2016, 04:27:09 pm »
Fortunately, we don't have consider your background or weigh your opinion because:

Well of course, you wouldn't because I'm speaking from direct experience which counters your beliefs. In that regard, you're just like the people who screwed up the program in the first place, by relying on beliefs instead of facts then spending the rest of the time trying to cover their asses, rather than admit their mistake. Thank you for making my argument for me, as noted below.

On the contrary, we have the Navy's chief engineers, DAB, JROC and independent consultants all attesting to the soundness of the design, the CONOPS and the requirements.
The Navy had in fact relaxed the weight requirements which it had acknowledged were too aggressive.  Even with GD/MD's weight growth the documents imply it was still lighter than NG's design. 

Yes, because the guys who screwed up in the first place by thinking they could get a stealth attack plane on the cheap would never lie to cover their asses, right?

Also, the USAF version was different from the USN version, as they insisted on having the nozzles exhaust on the top and flying the mission at altitude, since their studies (And experience, but they weren't talking about that at the time) had shown that flying a stealth aircraft on the deck wasn't a great idea. So, just for the record, the USAF wasn't completely on board with the A-12's mission profile.
« Last Edit: November 07, 2016, 04:36:12 pm by Sundog »

Offline NeilChapman

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #1061 on: November 07, 2016, 08:14:25 pm »
Thanks for sharing!

Offline kilokb

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #1062 on: November 07, 2016, 08:16:27 pm »
Roughly 25 years after  the rollout and there is still very little informatiom/images about the manufacturing of the YF-23.  I have seen quite a few images of both YF-22  prototypes during construction, but I don't think I've ever seen publicly released images of either  of the -23 PAVS
 :-\

Offline r3mu511

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #1063 on: November 08, 2016, 01:16:19 am »
I think I've read that the A-12's straight trailing edge gave a substantial RCS spike directly front due to surface diffraction and creeping wave returns.

trailing edge returns are actually dominated by edge diffraction contributions in the specular direction if edge alignment is the major concern (ie. concern over straight trailing edges)... the magnitude of the rcs contribution of the edge diffraction can be approximated by the length of the edge squared divided by pi (see equation 7.54 in ch.7 in "Introduction to the Uniform Theory of Diffraction", McNamara/Pistotius)...

with regards to edge location with respect to the incidence direction, trailing edges contribute an edge diffraction return when the electric field is polarized perpendicular to the edge (which can occur for linearly polarized waves where the E field is perpendicular to the trailing edge, or for circularly polarized waves where a component of the E field is perpendicular to the edge, figs. 7.6 and 7.8 in "Radar Cross Section", Knott/Shaeffer/Tuley)...

trailing edge diffraction actually drops considerably when viewed directly head on but rises quickly to the approximate value length^2/pi when the view angle rises slightly (see fig. 14.7 and accompanying discussion in "Radar Cross Section", Knott/Shaeffer/Tuley)...

---

in contrast traveling waves (ie. surface waves if on surfaces exposed to the incident radiation, or creeping waves if on surfaces shadowed from the incident radiation) would reflect back at a surface discontinuity (ie. current discontinuity) regardless of edge alignment but their contributions are typically on the order of the square of the incident wavelength and thus are much smaller compared to the edge diffraction return in the specular direction (ie. direction normal to the edge), traveling wave contributions are thus normally mitigated via surface RAM and/or materials to taper the currents as it nears the surface discontinuity (since it is the discontinuity of the currents at the edge of a surface which causes the reflection of the traveling wave to occur)...

---

given the difference in relative magnitudes of the two contributions (ie. "length^2/pi" for edge diffraction vs. "wavelength^2" for traveling waves), if edge alignment was the major concern (ie. straight edges were used) then it's likely the major concern of contribution was the edge diffraction return (under the assumption that short wavelengths were under consideration, and also under the assumption that the trailing edge was actually a metal structure, and not a dielectric covering a saw-tooth metal edge underneath)...

Offline Airplane

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Re: Northrop/McDonnell Douglas YF-23 and EMD F-23
« Reply #1064 on: November 08, 2016, 04:50:24 pm »
Roughly 25 years after  the rollout and there is still very little informatiom/images about the manufacturing of the YF-23.  I have seen quite a few images of both YF-22  prototypes during construction, but I don't think I've ever seen publicly released images of either  of the -23 PAVS
 :-\

Really? I remember over 26 years ago a written work about the manufacturing difficulties..... er, I mean challenges with the YF-23. What I read explained the construction of the double hump engine covering and how for the YF's it was metal with lots of fasteners and other things. In the production F-23 it would have been replaced by a lighter simpler composite blend which was would have also been easier to build than the metal prototype part.

I guess you need to go back in time when the ATF program was alive and kicking to find such info. There really isn't any need by anyone today to write papers or publish info on these "old" obsolete aircraft.
"The test of success is not what you do when your on top. Success is how high you bounce when you hit bottom.
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