Originally Posted By: Patarames
I agree its just a civilized discussion.

@ricnunes

I'm aware of quite some of the history of US stealth technology. You are right that the trade-off of stealth vs aerodynamic ratio is in favor of maneuverability for at least the same stealth characteristics. Point is that geometric stealth (behavior of waves reflecting the surface area) in the XST program was still some kind of black magic, Lockheed did it via computers, Northrop via experience and testing. But by the time of Tacit blue Northrop gained enough knowledge to get almost everything that was physically possible out of geometric stealth, the stealth method that is effective against VHF-band radars.
Even the F-117 should have made the very most of whats possible out of geometric stealth and the later tacit blue even had lower aerodynamic requirements, so that more emphasis on stealth design could be made.
This is why I think the VHF-band stealth performance of the tacit blue was good and still could be called state of the art and the F-117 also not much worse than F-22/35. Some people with wave physics knowledge claim that the B-2 is superior to everything due to its topological feature size which greatly degrades the benefits of VHF-band and its wave reflection behavior.

My 320km range value of F-35 vs Nebo-M is for the case that it performs 20 DBSM worse than in x-band for which it was optimized and in which its RAM and RAS come into the game. The value sounds huge I know but its the result of numbers and a sound looking chart interpretation of Hpasp, its weakpoint is that I proportionally also decreased the F-35 performance by 20 DBSM.



Please don't get me wrong but it seems that you're considering Tacit Blue as a sort of a pinnacle of Stealth aircraft development and technology (please, correct me if I'm wrong) while in fact it isn't. Actually it's very far from it.
In fact Tacit Blue was among the first US Stealth experiments which actually lead to a dead end.
One of the reasons was that as you correctly said, Lockheed developed Stealth aircraft using computer models which resulted in aircraft that were not only more agile and better performing but also and especially more stealthy.

Besides, Tacit Blue design seemed to be intended as a battlefield surveillance aircraft which would fly just behind the front lines (but still over friendly territory) or resuming, basically a similar role as JSTARS which means that Tacit Blue was never meant as an interdiction aircraft which would need to penetrate well inside enemy territory like the F-117 and thus it didn't have the same stealth requirements (like for example to defeat Early Warning and/or VHF radars) like the F-117, B-2, F-22 and F-35 have.

If there's any need for evidence on this, I can give you just one: The F-22 Raptor.

The F-22 Raptor is not only much more stealthier than Tacit Blue in every possible radar band but it's also extremely agile and much better performing and it looks much more like an actual fighter aircraft instead of some weird stuff taken from a 1950's Sci-Fi movie/TV-show (like Tacit Blue is).

And the F-35 follows this exact same trend as the F-22.

If you want to design a Stealth aircraft, a computer model is the only way to go since a computer model allows the design of stealth aircraft that are both more stealthy and much better performing - With a computer model you can experiment with much more variables while at the same time being exponentially much faster compared with any other kind of experiment like Tacit Blue.
For example, lets look at all US (and only) Stealth aircraft that ever entered in service: F-117, B-2, F-22 and F-35. All except one (B-2) were designed by Lockheed with the help of computer models.
The only exception, the B-2 which was designed by Northrop - which was also the designer of Tacit Blue - which used a design that had absolutely nothing to do with Tacit Blue. It used a flying wing design, a design that once again was found to be stealthy rather by accident.
And I'm willing to bet that even the B-2 design had some help by using computer models.

In the end, I believe that Tacit Blue can be considered to be somehow a "failed experiment".


So yes, I'm pretty sure that the F-35 is much more stealthier than the Tacit Blue against VHF radars.
Like Hpasp said, the B-2 was already stealthier in this regard against VHF radars compared to Tacit Blue and the US knows how instrumental was a VHF radar (P-18) in downing the F-117 over Serbia so I'm pretty sure that the US military and Lockheed Martin objectives include making the F-35 stealthy against VHF radars as well.


Therefore I agree with Hpasp, the dBsm gain of the F-35 RCS against VHF radars should be around or next to none/zero (0).


Originally Posted By: Patarames

As for jamming.
A Prowler 800km away brute force noise jamming all frequencies of an old, large sidelobe, non frequency hopping, low bandwidth P-18 radar still could degrade its performance to a level where its reduced by lets say 30%. Do we know that there was no degrading noise interference at the Serbian P-18? For 1999 NATO principles I would expect at least a general jamming even if not dedicated to that P-18.

As for the 0,005m² vs 0,16m² RCS values. They are based on different assumptions and simplifications, yes but I have shown how these numbers came into being. I would take that 20 DBSM delta value out of the Tacit blue documents with Hpasp scale interpretation as a logic number. The extrapolation of the Serbian F-117 encounter is also useful but just like there are uncertainties with the tacit blue chart scale, I suspect that jamming could have degraded the P-18 performance in that night.

They say engineering without numbers is not engineering. What I try to do here is extrapolating numbers via known facts and logic interpretations. I read Hpasp's post and found his formula for range and RCS, I used this new skill here in my calculations which created that 320km of Nebo-M against 20 DBSM degraded F-35.



There were no Prowlers available to support the downed F-117 over Serbia.
In the link below:

https://www.amazon.com/Stealth-Down-Fighter-Combat-Dramatic/dp/1886391491

Which is from a book on sale about the F-117 shot down over Serbia, you can read the following in the preview:

"For the first and only time during the air campaign, the Stealth fighters were sent into Serbia without EA-6B Prowlers that can jam enemy radars and also collect vital information about their location and operating parameters for pilots who are trying to avoid being shot down by surface-to-air missiles. Other aircraft like F-16CJs that carry high-speed anti-radiation missiles (HARMs), to knock out SAM sites, were also held outside the target area in central Serbia on the fourth night of the air campaign."

and this:

"Colonel Daniel "Doc" Zoerb, the Air Force officer who headed up the "Red Team," the official U.S. Air Force investigation of the shootdown for the Air Combat Command, says the HARM shooters and EA-6B electronic jammers were diverted to counter another threat that developed while the F-117s were en route to the target from Aviano Air Base in Italy."


Finally you can play this same scenario here in SAM Simulator - Hpasp has meticulously research hisorically all current scenarios in SAM Simulator - and you won't find any jammers and/or SEAD flights in there (like happened in real life - see link and description above).


Regarding the EA-6 Prowler jamming range, that's definitely not 800km as you say. I found the following page on F-16.net (an interesting site with lots of very interesting information) where a guy there quoted an article from Aviation Week (Jan. 2010) - which unfortunately I could not find - where it says that the standoff jamming range of the EA-6 Prowler was around 80 (eighty) nautical miles (mi) or resuming around 148Km.
Here's the page:
http://www.f-16.net/forum/viewtopic.php?t=13493