Does stratosphere act like stealth technology?

The SR-71 performed some amazing feats, including being shot at by no fewer than 1,000 GBAD (ground based air defense) systems. I suspected for some time that this feat didn't make sense from a purely speed and altitude story. Due to some secondary research on the MiG-31, another very capable aircraft that has stratospheric capability, and some background knowledge on the STS Orbiter and its radar signature problems, I think I've pieced together that there's something particularly problematic with the stratosphere.

Looking for evidence is difficult - so I open it to this community to discuss it.

The base-evidence I have that the stratosphere acts stealth-like for planes comes from attenuation from atmospheric gasses, a paper for satellite communications:
Attenuation by Atmospheric Gasses

This demonstrates that in the military frequencies usually 8GHz to 15GHz there in fact is an attenuation by H2O. Strangely O3 remains ELUSIVE. Which frustrates me but also leads me to think that in the US there is a general scrubbing of data on O3 attenuation. Considering the Wikipedia history of Taiwan basically begins at its discovery by the Dutch, in english speaking Wikipedia, I don't put it past the CIA/NSA etc to put some restrictions on information that is conspicuously absent.

Needless to say, the H2O contributes about 12 - 15 decibels of attenuation for 8GHz to 15GHz.

Based on this source, US goes for a stealth attenuation of about 15 to 25 decibels.
basicsaboutaerodynamicsandavionics.wordpress.com...

So arguably just from the H2O alone, being at that much higher altitude you get the full effects of water attenuation.

But again the O3 has been conspicuously absent in a lot of research, not because it doesn't contribute, but I'm interested in how it may contribute especially in super heated ionized state such as at the surface of a 426C surface temperature of a supersonic aircraft. Someday I may find that.

But you see where I'm going with this. Basically there's 2 avenues of stealth that may be derived from the stratosphere. I discussed the one above, but there's also atmospheric tunneling.

The phenomenon is well discussed at civilian levels due to its hindrance of air traffic controls at altitudes below 3,000 feet.

But, the phenomenon is actually a derivative of humid air overlaid by drier air. What stands out to me in the stratosphere isn't that it is "bone dry", because the atmospheric tunnel would be a relative physical property between the two layers, not an absolute physical property.

It's that the conditions for humid and then drier air exists in the stratosphere, right about the Ozone layer or the cruising altitude of the SR-71 and the MiG-31's combat ceiling which it goes to in war time.

This layer is where the temperature begins to reverse from ultra cold back to nearly standard temperature (20C) in the stratopause which is much higher than these aircraft ceilings.

But that layer where the temperature gradient inflects back to warmer is probably an atmospheric tunnel. It's another layer I cannot discover any discussion about in terms of Electromagnetic Atmospheric Tunneling.

Presumably it doesn't exist, so not much literature on it, but if it does exist, which I think it is physically possible, then it's simply suppressed information hard to find.

So if anyone wants to dive deep on either of these two ideas please feel free:

• Radar Attenuation by H2O or O3
  
• Atmospheric Tunnels causing Radar Blindness near the Ozone Layer
  

I'm far from done reading either your post or your first link, but... I thought sound was transmitted better in water than in the air. I guess water being droplets at that altitude helps in creating a sound barrier...

Also, I notice in your first link they say that nitrogen helps in the attenuation. What makes me raise my eyebrow here is the fact that there is a stupid movement that wants to remove nitrogen from farming for being bad.

hmm... haha Back to reading and thanks for this interesting information!

originally posted by: coamanach
I'm far from done reading either your post or your first link, but... I thought sound was transmitted better in water than in the air. I guess water being droplets at that altitude helps in creating a sound barrier...

Also, I notice in your first link they say that nitrogen helps in the attenuation. What makes me raise my eyebrow here is the fact that there is a stupid movement that wants to remove nitrogen from farming for being bad.

hmm... haha Back to reading and thanks for this interesting information!

It's not a sound attenuation it's an electromagnetic attenuation, I could have made that more clear. So in the ocean submarines take advantage of acoustic tunnels where sound only propagates within them etc. And these tunnels are also thermocline-dependent similar to the radar tunnels in the atmosphere.

The attenuation is a more direct evidence of stealthyness of the atmosphere, or we could say, opaqueness.

In the 8GHz-15GHz there's a certain opaqueness that altitude enhances due to added distance.

Seeing 200km might give you a visibility of 20 decibels at 10,000 feet. Which means at 80,000 feet you'd have approximately only 5 decibels of visibility. Not much at all.

Thank you for the clarification.. Haha, my mind was going into every directions...

You brought an interesting subject to table, and I know I'm going to learn a lot of stuff now.

a reply to: DarthTrader

It wasn't the stratosphere, it was speed and radar range. Non OTH radar has a pretty finite range around 250 miles, due to the curvature of the horizon. It increases with altitude, but you aren't going to see a lot more than that unless you're up pretty high. At 250ish miles, a Mach 3 target is going to be passing by pretty quickly. It also helps that, outside Vietnam and North Korea, the SR-71 wasn't overflying SAM systems a lot, so they were out on the fringes of detection range. They were more for side scan work that direct overflight, especially after Powers was shot down.

You may see some degradation of radar at high altitude, but the biggest thing with the Blackbird was speed vs range. It would take about 12 minutes to cross from horizon to horizon of the radar's range at 250 miles. That's not a long time to identify, lock on, launch, and the missiles to get to altitude.
And by the time they did, it was a tail chase, which means they'll lose.

originally posted by: Zaphod58
a reply to: DarthTrader

It wasn't the stratosphere, it was speed and radar range. Non OTH radar has a pretty finite range around 250 miles, due to the curvature of the horizon. It increases with altitude, but you aren't going to see a lot more than that unless you're up pretty high. At 250ish miles, a Mach 3 target is going to be passing by pretty quickly. It also helps that, outside Vietnam and North Korea, the SR-71 wasn't overflying SAM systems a lot, so they were out on the fringes of detection range. They were more for side scan work that direct overflight, especially after Powers was shot down.

You may see some degradation of radar at high altitude, but the biggest thing with the Blackbird was speed vs range. It would take about 12 minutes to cross from horizon to horizon of the radar's range at 250 miles. That's not a long time to identify, lock on, launch, and the missiles to get to altitude.
And by the time they did, it was a tail chase, which means they'll lose.

Radar guided missiles don't tail chase, they lead the target by computation, though I've seen simulations where an SR-71 could increase its vertical climb speed such that a missile would think it would reach its ceiling before intercept and terminate itself. That's theoretically one way to lose a radar guided missile.

An infrared was almost certainly incapable of hitting an SR-71, they are tail chasers.

If a GBAD battery takes 30 minutes to power-up and respond, there's also that, as you said, 12minutes horizon to horizon. You'd need quite a lot of layers of defense to respond effectively but if you did it probably could if the trickery described above could be worked out.

But tracking is not the same as searching, a large array on the ground may know you're there, but getting close enough for enough radar resolution to hit something is the other part of the equation. If losing 12 decibels is true then that could have been the "edge".

It may still apply to the Mig-31 today. Which is interesting to me since they are running combat sorties.

a reply to: DarthTrader

The SR-71 also had a bleeding edge EW suite that is still not talked about today. What little has been said was that it more or less guaranteed a miss once activated.

originally posted by: Zaphod58
a reply to: DarthTrader

The SR-71 also had a bleeding edge EW suite that is still not talked about today. What little has been said was that it more or less guaranteed a miss once activated.

For others, this guy has a great introduction to EW:
www.youtube.com...

I can't imagine any EW system would guarantee a miss. I'm very curious what the heck went wrong with B-52 New Years bombing in Vietnam where what, 8 were shot down and 4 more damaged? Something like that.

The tech is comparable ~ 1973 to 1980. I am curious if today's DIRCM and tube radar and other techniques could guarantee a miss today, greatly improving the B-52 (and arguably an SR-71).

The guy I cited above talks about his experience chasing a supersonic plane and how its use of that tubular radar became a constant cat-and-mouse game where he'd constantly lose tracking and have to reacquire.

Modern computers may make that more difficult now though especially with AESA which rapidly goes through many frequencies.....but for the purposes of this discussion a supersonic cruise with that radar jamming technique proved very capable even at just 1.5mach.

Edit- when I say tubular radar what I'm referring to is a "travelling wave tube".

a reply to: DarthTrader

The B-52s were using the same callsign, launch time, route, and turn points on multiple nights. Once they were allowed to change tactics their losses dropped off significantly.

a reply to: DarthTrader

The ozone layer is a lot closer to space higher than i would hazard a guess no air breathing jet can reach.

You might be able to use something like HARP or a really strong radar to make false points in the sky or maybe even just fuzz out an entire radar screen, i feel like that would be impossible today barring unlimited signal processing and power.

Anything moving in a charged medium would be detected, likely not firing resolution but enough to tell something is there.

I think the tried and true method of sneaking in as high and as fast as you can, at least for the foreseeable future is going to be the best way to get some sneaky intel.

a reply to: Zaphod58

Remember reading was a near mutiny by B 52 crews against the weenies at SAC assigning them the same ingress/egress routes, call signs, altitude for the bombing runs

Once crews were able to plot their own mission profiles the losses decreased

Also several B 52 tail gunners were credited with downing NVA Mig 21 attempting to intercept B52, probably last ones ever see ......

a reply to: Zaphod58