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The SR-71's predecessor used cesium-laced fuel to create radar-absorbing exhaust

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Re: The SR-71's predecessor used cesium-laced fuel to create radar-absorbing exhaust

#131

Post by AWildC182 »

jpmattia wrote: post #125

I would love to know the thinking behind this method. Off the top of my head: They are adding Cesium ("screw the environment, I have to escape my pursuer") to the engine in order to leave a plasmonic plume. The plasma, which occurs because the electrons in Cesium are stripped off in the heat of the engine, absorbs microwaves (ie, radar) because of the expected cyclotron physics of a free-electron gas. However as an e…

For these kinds of radars, there won't really be any signal against the sky and, lets be honest here, nothing is going to be looking at the SR-71 from a top down aspect. In a tail chase situation though, a missile would have to fly straight at the exhaust which would give the aircraft some cover.

There's a bit of reading between the lines that needs to be done here though. The aircraft is already shaped to deflect radar waves from a tail or nose on aspect but the part that's very hard to 'stealth' is the insides of the engines, especially from the rear aspect. Turbine blades and all the other geometry inside tends to act like a radar disco-ball and leaves even many modern aircraft vulnerable. By making the exhaust radar absorbent you fix this issue.

Re: The SR-71's predecessor used cesium-laced fuel to create radar-absorbing exhaust

#132

Post by dkersten »

jbattle wrote: post #117
wbl wrote: post #95

Earlier quoted context omitted.

Astronomy includes knowing when you aren't doing it and instead seeing an artifact of your instruments or weather.

> Astronomy includes knowing when you aren't doing it and instead seeing an artifact of your instruments or weather One would hope fighter pilots have some faculty in said skills!

Sure, but the universe has a lot of very strange natural phenomena and astrophysicist spend a lot of time studying these and therefore can recognise when something is likely natural (or at least have the background knowledge to check before assuming its aliens -- as they say, its never aliens, until it is) where a fighter pilot might be more attuned to seeing things in the sky than the average person, they still don't have the same exposure and experience seeing, studying and working with strange sky and space phenomena. I'd rather an astrophysicist's opinion on aliens than a fighter pilot's, but I'd rather a fighter pilot's opinion than my local plumber.

Re: The SR-71's predecessor used cesium-laced fuel to create radar-absorbing exhaust

#133

Post by mannykannot »

ohiovr wrote: post #103

Isn't caesium kind of hugely expensive?

The original source of this additive (or the raw materials for it) was a waste product from detergent manufacture. When that method of detergent production was discontinued, they needed to set up an alternative source, which no doubt raised the cost, but everything about the A12 / SR71 was hugely expensive.

Re: The SR-71's predecessor used cesium-laced fuel to create radar-absorbing exhaust

#134

Post by aaronblohowiak »

_jal wrote: post #106
faizshah wrote: post #50

Earlier quoted context omitted.

Some cool ones here: https://www.computerhistory.org/collections/fairchild/ Would be cool to see some old notebooks from Bell Labs tho like Ritchie or Thompson. I just found some old AT&T training manuals on Perl, TCP/IP, Bash, C and Unix internals, they are really cool.

Along the same lines, my bedside-book for the last few months has been Engineering and Operations in the Bell System[1]. It is... from another time. Both the quality of the engineering and the quality of the documentation simply don't happen anymore outside of very narrow niches. And then you look at the Death Star now, and their core competency is lobbying. Priorities certainly have changed. [1] https://www.worldcat…

>the quality of the engineering and the quality of the documentation simply don't happen anymore outside of very narrow niches

Wasn't Bell Labs a narrow niche at the time?

Re: The SR-71's predecessor used cesium-laced fuel to create radar-absorbing exhaust

#135

Post by blakes »

jpmattia wrote: post #125

I would love to know the thinking behind this method. Off the top of my head: They are adding Cesium ("screw the environment, I have to escape my pursuer") to the engine in order to leave a plasmonic plume. The plasma, which occurs because the electrons in Cesium are stripped off in the heat of the engine, absorbs microwaves (ie, radar) because of the expected cyclotron physics of a free-electron gas. However as an e…

Apparently in some aircraft, the radar cross section of the exhaust is easier to spot than the aircraft itself.

Re: The SR-71's predecessor used cesium-laced fuel to create radar-absorbing exhaust

#136

Post by tempguy9999 »

jacobush wrote: post #119
tempguy9999 wrote: post #78

Earlier quoted context omitted.

> I know it's toxic but from a technical aspect, that is really cool. People who think like this make want to cry. Those who can see the consequences and choose to overlook them.

You comment is toxic but from a technical aspect, really cool. I choose to overlook it.

Your comment went so far over my head I knew none of it, only the faintest settling of toxic caesium particulates in my lungs gave me any clue it was ever there.

Re: The SR-71's predecessor used cesium-laced fuel to create radar-absorbing exhaust

#137

Post by partialrecall »

dkersten wrote: post #91
austinheap wrote: post #69

Earlier quoted context omitted.

NY Times: ‘Wow, What Is That?’ Navy Pilots Report Unexplained Flying Objects https://www.nytimes.com/2019/05/26/us/politics/ufo-sightings...

As Neil Degrasse Tyson once said, even pilots aren't astronomers or astrophysicists and often don't know what they're seeing when they look at the sky.

As I understand it, in at least some of these instances the pilots were looking down at the ground when they claim to have seen objects beneath them. /nitpick

Re: The SR-71's predecessor used cesium-laced fuel to create radar-absorbing exhaust

#138

Post by bigfudge »

manigandham wrote: post #56
throwawaynihil wrote: post #49

The science and technology is awe-inspiring .. as in awwww-mother fucker, we could have had universal healthcare and a peaceful world if we didn't spend trillions of dollars on this bullshit.

These recon and offensive capabilities have in fact led to a more peaceful world. It’s the harsh reality that we live in.

Citation needed. From a non US perspective the world looks a little different.

Re: The SR-71's predecessor used cesium-laced fuel to create radar-absorbing exhaust

#139

Post by avar »

willvarfar wrote: post #74
avar wrote: post #62

Earlier quoted context omitted.

Turkey already bought F-35s[1], but are being told both that they can't buy anymore, and the servicing of the engines will be moved out of Turkey by 2020 if they insist on buying the S-400 from Russia[2][3]. Also, even if they didn't sell the F-35 to Turkey but still serviced the engines there that would make logical sense. The reason the US is paranoid about the S-400 is because they think radar data about the F-35…

From my reading, I don't think any of the F35s had been delivered, but some Turkish pilots had started training in the US in '18. That is now stopped. Over 900 parts in the F35 were made by Turkish companies, and they have to now be re-sourced. Now, I don't think the F35 operators want F35 engines sitting around in a country now receiving Russian military advisers. The idea that the engine isn't classified is crazy.

I believe Turkey owns those F-35s operating in the US, they're used for training. On that Wikipedia page you can see there's dozens of F-35s in the US owned by foreign air forces.

Can they just fly them out of the US at this point? No idea, but it's interesting to see what'll happen with that.

Just because Russia has S-400 advisors in Turkey doesn't mean they get to walk around wherever they want, including wherever the F-35's engines are serviced.

The concern was specifically that they'd have access to detailed radar data on the F-35, which they'd have access to in their roles as advisors for the S-400 missile system.

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