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The SR-71's predecessor used cesium-laced fuel to create radar-absorbing exhaust
- liability 7y agoThat's one hell of a "chemtrail"!
- netfl0 7y agoProbably not good.
- robohoe 7y agoIf you're curious about the development of Oxcart as well as Area-51, check out Amy Jacobson's Area 51 book[1]. Appears like a solid detail of Skunkworks and spy plane history. [1] https://www.amazon.com/Area-51-Uncensored-Americas-Military/dp/0316202304/ref=sr_1_fkmr1_1?keywords=Area+51+Amy+jacobson&qid=1568341816&s=gateway&sr=8-1-fkmr1 https://www.amazon.com/Area-51-Uncensored-Americas-Military/...
- syntaxing 7y agoI know it's toxic but from a technical aspect, that is really cool. I remember reading that the Apache Helicopter (I think?) can redirect it's exhaust internally temporarily to become invisible to heat seekers. Some of these technologies are super fun to read about.
- vvanders 7y agoSome of the stuff to restart the afterburners was pretty nasty too. I think it was one of the hypergolic families if I remember correctly.
- IcePenguin 7y agoYep! It's called TEB (Triethylborane). More info here: https://en.wikipedia.org/wiki/Triethylborane https://en.wikipedia.org/wiki/Triethylborane JP-7 has a very high ignition temperature (it was actually used as a coolant/heat sink for the rest of the aircraft), so TEB combusting once it hit the air is used to light the engines. SR-71s only had a limited amount of TEB to use each flight. I believe it was 13 shots per engine. TEB was used each time the engines were lit and also when afterburners were lit. While the SR-71's routes were built around refueling, the number of TEB shots remaining were the true limiting factor of the SR-71's flight time.
- jazzyjackson 7y agoI don’t know anything about afterburners, if it’s the same fuel as the usual engine, what about it needs to be lit with a lower temperature fuel? I always assumed afterburners just meant opening the throttle up but there must be more to it
- jabl 7y ago> I always assumed afterburners just meant opening the throttle up but there must be more to it No, as the name implies it's literally pouring in fuel after the turbine, in the exhaust. The exhaust is hot, yes, but cooler than the combustion chambers (which reside in between the turbine and compressor). So if you have some special fuel that's very hard to ignite then maybe you need some help to get the afterburning started.
- coolspot 7y agoMost military helicopters having some ways of masking IR signature: https://www.sciencedirect.com/science/article/pii/S1000936114000168 https://www.sciencedirect.com/science/article/pii/S100093611...
- austinheap 7y ago1960s designs cannot be masked against modern FLIR arrays so old rotorcraft still in service are just retrofitted to discourage detection.
- decoyworker 7y agohttps://en.wikipedia.org/wiki/Common_Infrared_Countermeasures_program https://en.wikipedia.org/wiki/Common_Infrared_Countermeasure... >Infrared guidance systems in heat-seeking missiles are designed to track strong sources of infrared radiation >Directional IRCM, or DIRCM, allows for a countermeasures laser to be targeted directly at an incoming IR threat.
- blackflame7000 7y agoIt depends. If its regular Cesium 133 then it's harmless compared to Cesium 137.
- taneq 7y agoThe Comanche vented its turbine exhaust into the wash from the tail rotor, iirc, to make it harder to spot. It also used a 5-blade rotor instead of the traditional 2-blade rotor in order to make it quieter. There's a bunch of cool things we could do to make helicopters more stealthy if we cared enough.
- DuskStar 7y agoAnd if you look at the US Army's Future Vertical Lift competition, [0] you can see some indications that those techs might make it into our future helicopters. 0: https://en.wikipedia.org/wiki/Future_Vertical_Lift https://en.wikipedia.org/wiki/Future_Vertical_Lift
- Daniel_sk 7y agoThere is some stealth helicopter model that is secret and was used in the operation to kill Osama, it may be a heavily modified UH-60.
- snowwrestler 7y agoMy recollection is that the contemporary reporting was pretty specific about what it was: an existing chopper with stealth tech grafted on. Something about that (the weight or shape) reduced lift and led to a crash landing during the mission. Some Google around NYTimes would probably turn up the details.
- showerst 7y agoThe story I heard at the time was that it was a combination of the stealth helicopters having lousy low-hover performance, and that during training they'd mocked a nearby solid wall up with a chain-link fence, which led to picking a poor landing zone.
- tempguy9999 7y ago> 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.
- pineconeInMyAss 7y ago>engineer: hey wouldn't it be cool if ... >tempguy9999: https://www.youtube.com/watch?v=WWaLxFIVX1s https://www.youtube.com/watch?v=WWaLxFIVX1s thank you for your service, noble internet warrior!
- jacobush 7y agoYou comment is toxic but from a technical aspect, really cool. I choose to overlook it.
- tempguy9999 7y agoYour 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.
- cafebabbe 7y ago"I know it's toxic but from a technical aspect, that is really cool" is a great alternative HN tagline
- skunkworker 7y agoIf you haven't read it, Skunk Works: A Personal Memoir of My Years at Lockheed by Ben Rich is a pretty fun read into the U2, A-12 Oxcart, SR-71, Sea Shadow and other craft. And has a lot of good stories from pilots. But the ultimate SR-71 book would be Sled Driver: Flying the World's Fastest Jet.
- galangalalgol 7y agoThe sr-71 gets all the glory but go look at some of the aircraft that lost competitions. The convair kingfish that lost to the 71 was decades ahead. It lost for a number of reasons, some valid, some not. The f-22 competitor was super interesting as well.
- aidenn0 7y agoYeah, the YF-23 wins a lot of cool points on looks alone[1], and it was faster and stealthier than the F-22. Taking the -22 was probably the right choice given that it was lower risk and absurdly better than anything it's likely to encounter in its operational life. 1: https://en.wikipedia.org/wiki/Northrop_YF-23#/media/File:YF-23_top_view.jpg https://en.wikipedia.org/wiki/Northrop_YF-23#/media/File:YF-...
- blackflame7000 7y agoIt seems the Airforce likes their bombers from Northrop, their fighters from Lockheed, and unmanned vehicles from Boeing.
- farseer 7y agoThere are a lot of political and national security concerns involved in that. The Air Force wants to maintain three aviation vendors in the industry as a matter of policy, otherwise Boeing and Lockheed are equally capable of making bombers. Awarding the JSF to Lockheed two decades earlier had similar connotations. Boeing could maintain its aviation capabilities and expertise on the back of its commercial business. For Lockheed, losing the JSF would have meant the end of its aviation unit which the USAF deemed critical for national security.
- tlb 7y ago> It’s also not clear from the available records how much [cesium] was necessary per gallon of [jet fuel] Come on, you lazy reporter! Go find a jet engine and some cesium and a radar reflectometer and make a graph of reflectance vs. cesium content. Presumably, some engineer at Lockheed in the late 50s got exactly that assignment, with a budget. There would be a notebook with a table of numbers and a hand-drawn graph. Those would be amazing to see.
- pg_is_a_butt 7y agoMight want to cross reference the Nazi studies about what that concentration of spent cesium would do to a human population living below over time.
- VonGuard 7y agoI have visions of exploding journalists.... For Reference: https://www.youtube.com/watch?v=m55kgyApYrY https://www.youtube.com/watch?v=m55kgyApYrY
- taneq 7y agoDo you have visions in higher than 240p? :S
- taneq 7y agoI would love to see some kind of web database of old engineering notebooks like this, surely there are enough now kicking around in boxes of "grandad's junk".
- CamperBob2 7y agoA nice one from Tektronix, c. 1979, just surfaced: http://w140.com/tekwiki/images/b/bd/Tek_7854_design_team.pdf http://w140.com/tekwiki/images/b/bd/Tek_7854_design_team.pdf
- faizshah 7y agoSome cool ones here: https://www.computerhistory.org/collections/fairchild/ 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.
- treggle 7y agoOf course, because nothing matters more than getting the advantage. Same line of thinking that results in depleted uranium tank shells.
- amluto 7y agoCesium (in the +1 state) appears to be barely toxic at all. Wikipedia puts its LD50 around that of sodium. Cesium metal is extraordinarily dangerous, but it’s so reactive that none of it will survive long enough to get anywhere near the ground.
- blackflame7000 7y agoYea it's Cesium 137 that everyone worries about and it comes from splitting uranium.
- jhayward 7y agoI have some bad news. We used to put tetraethyl lead in automobile fuel and then burn it in cities next to homes and schools.
- saagarjha 7y agoMore bad news: we still put it in avgas.
- tjohns 7y agoThey're working on a replacement for 100LL avgas, thankfully. There's some flight safety concerns that have delayed it, but it's still a work in progress.
- jabl 7y agoLast I heard the project has stalled. And with the current administration there's unlikely to be political pressure to get it rolling.
- leeoniya 7y agomy favorite A-12 read: https://www.otherhand.org/home-page/area-51-and-other-strange-places/bluefire-main/bluefire/the-hunt-for-928/ https://www.otherhand.org/home-page/area-51-and-other-strang... that whole site is full of awesome accounts of his adventures out west.
- willvarfar 7y agoMy favorite A12 talk: https://www.youtube.com/watch?v=MGdxpqqsHl8 https://www.youtube.com/watch?v=MGdxpqqsHl8 Frank Murray's talk is full of great facts, insight, yarns and stuff. Still as sharp as a tack. There are lots of other interviews with A12 and SR71 and other interesting planes on youtube. Be warned: an HNer could lose days browsing there ;)
- exabrial 7y ago> Though there is no indication that A-50 used a radioactive cesium isotope, the compound is toxic and it's unclear how hazardous the complete mixture may have been
- dschuetz 7y agoI think, adding anything radioactive to jetfuel even with decay halflifes of some days would leave a detectable trail.
- purnama777 7y agoit's good I hope to use it
- nullc 7y agoMy experience with cesium is that everyone thinks its radioactive. It isn't-- like many common elements there is a radioactive isotope, but that is not what would have been used here. I speculate this worked by the highly reactive cesium ionizing the air. Similar things have been done with doping rocket fuels with metals to stimulate lightning strikes. Presumably most of the cesium would end up reacted very quickly, I don't know what the products would be but plenty of obvious candidates like cesium carbonate appear to be non-toxic.
- dschuetz 7y agoWell, you are correct in just some cases. Caesium has only one stable isotope, so beside the actual Caesium and Caesium-133 everything else has ß-decay. Unless you are burning 100% refined Caesium, there is always a chance that you are also burning its radioactive isotopes.
- nullc 7y agoAll the isotopes of Cs other than 133 exist only in negligible amounts in nature. So sure, perhaps there would be a trace amount of something else-- but that is true of anything.
- ohiovr 7y agoCaesium is the easiest metal to ionize. It also has a fairly low work function. So it is easy to turn the metal into a plasma.
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- AleksReed 7y ago)
- throwawaynihil 7y agoThe 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.
- manigandham 7y agoThese recon and offensive capabilities have in fact led to a more peaceful world. It’s the harsh reality that we live in.
- acqq 7y agoThe capabilities actually used were and are a real overkill, for many orders of magnitude. The whole think tanks and whole branches of military from the start worked on many order of magnitudes multiplied assumptions of the military capability of the opponents. Only now you can read their acknowledgment that the estimates were hugely overblown (1). So they did produce overkill from the start as they produced "enough" rockets and planes. Then they replaced the plain nuclear warheads with the thermonuclear warheads, again many orders of magnitude overkill. And the "victory" is defined as destroying more than the opponent, no matter if anybody would be able to live in the world afterwards. Against the fact that the world was never so interdependent as it is now -- if you would remove all the stuff from your possession where at least some parts were produced in e.g. Asia, you would not have almost anything useful. We're still in the world that can lose the form as we know it in just one erroneous decision, even if some humans in some caves/shelters manage to survive, what's left will be worse than the most pessimistic movies. And in that world, just the cost of a single type of the plane (F-35) is projected (that means lower than what will be) to 1.508 trillion dollars. And the US just exited one nuclear arm control treaty. 1) E.g. in my favorite book: "The Doomsday Machine -- Confessions of a Nuclear War Planner" written by a former strategic analyst at the RAND Corporation.
- manigandham 7y agoYes, it's rather cynical. And yet it's this very tension that keeps the peace. The world is now in the longest stretch of world-wide peacetime ever in history.
- manigandham 7y agoThere’s a fantastic recent special on the history channel about the Skunk Works, Kelly Johnson, and the development of the SR-71 Secrets in the Sky: The Untold Story of Skunk Works: https://www.history.com/specials/secrets-in-the-sky-the-untold-story-of-skunk-works https://www.history.com/specials/secrets-in-the-sky-the-unto...
- kyoledemon17 7y agoGreat
- ngotienvinh 7y agoI need to buy multiple hacker news or github accounts, it needs to be created before September. My Contact: ngovinh2026@gmail.com
- ohiovr 7y agoIsn't caesium kind of hugely expensive?
- mannykannot 7y agoThe 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.
- iflypropplanes 7y agoFor those in NYC, there is an A-12 on display on the deck of the Intrepid. 100% worth the visit
- hsnewman 7y agoI've heard chem trail conspiracy theories, it seems that there is a hint of truth in them, but still ridiculous. https://en.wikipedia.org/wiki/Chemtrail_conspiracy_theory https://en.wikipedia.org/wiki/Chemtrail_conspiracy_theory
- myth_drannon 7y agoWe need to give a proper credit to the Soviet physicist Petr Ufimtsev (https://en.wikipedia.org/wiki/Petr_Ufimtsev https://en.wikipedia.org/wiki/Petr_Ufimtsev) who's published papers in 60's on reflection of electromagnetic waves were read by Lockheed Martin engineers and that started the stealth program.
- dev_dull 7y ago> He gained permission to publish his research results internationally because they were considered to be of no significant military or economic value. A decision I'm sure the Soviet Union would quickly come to regret.
- jpmattia 7y agoI 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 electronic countermeasure, I do not see the point. The plasmonic plume will absorb the microwaves where the rest of the plane will continue to reflect it. To my thinking, the is exactly what you do not want to do: You've reduced the microwave signal where the plane is not present, and done nothing to the signal where the plane is present. So you've improved the signal-to-noise for the enemy, which are providing guidance for anti-aircraft missiles. Considering how many years this program went on for, my thinking must be wrong. Maybe anti-aircraft missiles of the era did not intercept from oblique angles (which takes serious computation and sensors) but could only hit from behind (where the plume would attenuate a signal)?
- AWildC182 7y agoFor 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.
- blakes 7y agoApparently in some aircraft, the radar cross section of the exhaust is easier to spot than the aircraft itself.
- efrafa 7y agoNot really related to the article, but this short speed story with SR-71 Pilot is so fun! https://www.youtube.com/watch?v=ILop3Kn3JO8 https://www.youtube.com/watch?v=ILop3Kn3JO8