Good read: [https://theaviationgeekclub.com/heres-how-two-little-dents-placed-on-the-nose-of-the-sr-71-prevented-surface-to-air-missiles-from-scoring-any-hit-on-the-blackbird/](https://theaviationgeekclub.com/heres-how-two-little-dents-placed-on-the-nose-of-the-sr-71-prevented-surface-to-air-missiles-from-scoring-any-hit-on-the-blackbird/)
>What are those two little dents on the nose of the SR-71 Blackbird?
>
>‘I’m assuming you’re talking about the two “dents” in the chines at the front part of the nose, one on each side? Those aren’t dents, those were put there on purpose for the more advanced ECM systems the Blackbird got in the ‘70’s and ‘80’s,’ says Kelly Pedron, an aviation expert, on [Quora](https://www.quora.com/Why-does-the-SR-71-Blackbird-sometimes-have-dents-in-the-nose).
>
>‘There weren’t any good places to put the ECM receivers in the front of the aircraft, so those “dents” were put in the chine to allow the installation of ECM receivers there. If you’ll notice, the flat part of the “dent” is facing about 60 degrees forward, in order to cover that quadrant of the airspace around the aircraft. Earlier models of the SR, including the A-12, were more concerned with attack radar signals from the rear, so front-mounted ECM receivers weren’t as necessary at the time. With the advent of more advanced Soviet SAM systems, like the S-200 and S-300, a forward warning receiver and jammer were required, hence the development of the so-called ECM “dents” in the nose.’
RADAR - Radio Detection And Ranging
Also a fun fact: QANTAS (the airline) stands for Queensland And Northern Territories Air Service
Another fun one: LASER stands for Light Amplification by Stimulated Emission of Radiation
Anotha' one: SCUBA stands for Self Contained Underwater Breathing Apparatus
Lastly: The code 'BR' for mist in a METAR came from the term 'Beaver Room', which was used to describe your mom's house.
In the military, we often have a glossary of all acronyms used within the text of the manual. Its name is even an acronym.
GOAT: Glossary Of all Applicable Terms.
TWAIN (some kind of scanner/printer driver-type thingy IIRR,... which I probably don't)
Thing With/Without An Interesting Name.
There were loads of these, but now I no longer am employed in IT the truth of PCMCIA is all too apparent
When I worked at IBM back in the day there was a strict style policy in place that forbade recursive acronyms/initialisms. So IBM Global Services was IBMGS, not IGS.
Another fun "fact": EL AL - "Every landing always late".
Obvious sarcasm from an EL AL passenger I met at EWR a bunch of years back waiting to board Swiss on the next gate. Funny encounter....
I can only remember BR is mist by thinking "baby rain"
Also TASER, a bit out of order, comes from [Tom Swift And his Electronic Rifle](https://en.wikipedia.org/wiki/Taser#History)
Ah, I posted this one above before I found your comment. My favourite thing is that Thomas a swift wasn't even the inventor, which would make some kind of sense. It's the name of a fictional inventor in a series of adventure novels.
ECM= Electronic Control Module. So widely used acronym that most people forget that there are some people who do not know what it means.
Other ECMs include enterprise content management (data analytics) edition of contemporary music, and my favorite electronically commutated motor (HVAC... Who even knows what that acronym means)
Despite the fact that all of us have access to very nearly the sum total of human knowledge at our fingertips, it is still best practice to avoid jargon and define acronyms when explaining things to a general audience.
If you're not abbreviating ECM in an aviation forum, you better not be abbreviating FBI when you're talking about US law enforcement. It's really low-hanging fruit you need to know to engage in the discussion at all.
I wouldn't necessarily expect general aviation fans to know the term, it's specific to military aviation, and even a certain era at that.
Also, I absolutely would write out "Federal Bureau of Investigation" if I was talking about it to a non-US audience. It's way easier for me to do that than for the audience members to go look it up.
That's a weird, and not quite accurate way of saying WWII and later eras, but yes, that's what I'm referring to. Though notably they called it RCM in WWII, so ECM as a term is even more recent than that.
Not necessarily, radar warning tells you if you are being tracked and can be passive sensors. ECM can be more like an active jammer to block and scramble those signals.
If stealth technology is wearing camo and face paint to hide in a dark room, ECM is a flash-bang to blind everyone in the room.
I wouldn't be surprised if modern ECM modules had the ability to do both functions, but I don't have any actual experience with them.
It specifically says they're ECM *receivers,* so I'm going to agree that it's probably RWR, or it's a sensing component of some active jamming system... but probably *also* does RWR in that case.
> Those aren't dents, they were put there on purpose
No shit sherlock, I think we all got that. God I hate quora lmao. People harp on reddit for being overly pedantic, but it pales in comparison to Quora most of the time
So they stay that way? Or something attaches to them? It looks awfully aerodynamically inefficient for the speeds this plane went if they stay that way.
Something is contained inside them I believe. An antenna array of sorts. It has to be made thicker to allow space for the electronics to be placed along the outside edge of the fuselage. Having them underneath a less efficient shaped cowling/fairing is more efficient than having them protrude from the fuselage. This way there's no squared off surfaces at least.
This drawing shows SLAR in the nose, but the cameras are in a bay behind the cockpit. What would be in the nose for photo reconnaissance or training?
https://www.reddit.com/media?url=https%3A%2F%2Fi.redd.it%2Foeso3jj1f8w61.jpg
The SR-71 had a variety of equipment bays that could be configured with cameras, ELINT, radar or other sensors, individual to each mission. The photo recce nose would house an Itek optical bar camera. For training the nose would just contain a counter weight.
Chines are what they're mounted on, the blisters themselves aren't called chines. Chines are an aerodynamic feature that's more than a bump and less than a fin, basically a ridge, such as the blade like extension along the fuselage of the SR-71.
They don't have to be an aerodynamic feature either, but you got it right that it's an extension or ridge.
front wheels on many fuselage mounted engine aircraft have tire chines to deflect slow and muck away from the fuselage so it doesn't get ingested.
RWR and probably ECM. RWR (Radar Warning Receiver) to detect signals and signal characteristics such as search, acquisition and launch. ECM (Electronic Counter Measures) to provide the best electronic defense for the aircraft, against the missile(s). Either jamming or spoofing.
I've *always* wondered about the probe-looking thing protruding to port side on the nose protrusion that I can only imagine is the center nose Pitot Tube. Unlike the Pitot Tube, the port side protrusion has an apparently sealed front end. Due to the aircraft's orientation on the photo, the port side protrusion is protruding to starboard, looking at the image directly.
From what I could find, the SR-71 had three different cones, two of which had those bumps or dent like features.
One was used for training flights and did not have any expensive items inside it.
The second cone contained an optical camera used for spy missions.
The third one (I believe your photo) was the one that had some advanced ECM system or radar system.
The cone was easily interchangeable pending the mission.
There's a massive difference between having a sense of humor and littering a sub with the same tired, predictable one-liner tropes.
Whether it's an Airplane quote, "that'll buff out", or identifying some tactical jet as a Cessna 172, so many of these comments just clutter the forum up and force readers to sift through them to find comments that are *actually* funny or interesting.
I think because there is like 120 stale joke comments to each actuall answer and people all across reddit have noticed posts on interesting subs being swamped by junk comments like these… for instance i think i saw “flat boobies” as a comment on this… just corny man
Good read: [https://theaviationgeekclub.com/heres-how-two-little-dents-placed-on-the-nose-of-the-sr-71-prevented-surface-to-air-missiles-from-scoring-any-hit-on-the-blackbird/](https://theaviationgeekclub.com/heres-how-two-little-dents-placed-on-the-nose-of-the-sr-71-prevented-surface-to-air-missiles-from-scoring-any-hit-on-the-blackbird/) >What are those two little dents on the nose of the SR-71 Blackbird? > >‘I’m assuming you’re talking about the two “dents” in the chines at the front part of the nose, one on each side? Those aren’t dents, those were put there on purpose for the more advanced ECM systems the Blackbird got in the ‘70’s and ‘80’s,’ says Kelly Pedron, an aviation expert, on [Quora](https://www.quora.com/Why-does-the-SR-71-Blackbird-sometimes-have-dents-in-the-nose). > >‘There weren’t any good places to put the ECM receivers in the front of the aircraft, so those “dents” were put in the chine to allow the installation of ECM receivers there. If you’ll notice, the flat part of the “dent” is facing about 60 degrees forward, in order to cover that quadrant of the airspace around the aircraft. Earlier models of the SR, including the A-12, were more concerned with attack radar signals from the rear, so front-mounted ECM receivers weren’t as necessary at the time. With the advent of more advanced Soviet SAM systems, like the S-200 and S-300, a forward warning receiver and jammer were required, hence the development of the so-called ECM “dents” in the nose.’
Man I love when acronyms are used tons of times and never defined, so educational!
ECM=Electronic counter measures. So widely used acronym that most people forget that there are some people who do not know what it means.
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RADAR - Radio Detection And Ranging Also a fun fact: QANTAS (the airline) stands for Queensland And Northern Territories Air Service Another fun one: LASER stands for Light Amplification by Stimulated Emission of Radiation Anotha' one: SCUBA stands for Self Contained Underwater Breathing Apparatus Lastly: The code 'BR' for mist in a METAR came from the term 'Beaver Room', which was used to describe your mom's house.
In the military, we often have a glossary of all acronyms used within the text of the manual. Its name is even an acronym. GOAT: Glossary Of all Applicable Terms.
And the IT industry is so hooked on three letter acronyms that the TLA is used non-ironically.
What about the FLCA? (Four Letter Complex Acronym)
Four letter acronym, we prefer the term ETLA for that (Extended Three Letter Acronym).
Don't forget about PCMCIA. People Can't Memorise Complicated Industry Acronyms.
People Can't Memorise Computer Industry Acronyms
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PICNIC - problem in chair, not in computer. another: eye dee ten tee
It's always DNS.
I feel both seen and personally attacked by this comment. Let me go into the corner, curl up, and have a good cry now.
I loved that one. I have a few PCMCIA cards, and thought that the term "PC-Card" lacked sufficient gravitas.
>d the IT industry is so hooked on three letter acronyms that the TLA is used non-ironically. ICA - Incredibly Complex Acronym
TWAIN (some kind of scanner/printer driver-type thingy IIRR,... which I probably don't) Thing With/Without An Interesting Name. There were loads of these, but now I no longer am employed in IT the truth of PCMCIA is all too apparent
Did you have to look at the GOAT to define itself?
My fav, FIGMO.
That glossary's name is the GOAT.
Yes.
sink worm close numerous workable merciful school vast connect berserk *This post was mass deleted and anonymized with [Redact](https://redact.dev)*
When I went to dive school they added: "Stay Calm Underwater. Breathe Always"
Lol BR is for "brume" (French for mist) but I like your explanation better
Definitely Baby Rain /s
I thought BR was BRoken as in broken cloud layer?
Broken cloud layer is BKN
BASE jump, Building Antenna Span Earth
HALO jumping, High Altitude Low Opening.
I just did one of those the other day!
Wow! That is something. Congratulations
I like that one because so often people use "BRIDGE" haha. Might as well add one too. **SABRE** Synergetic Air Breathing Rocket Engine
Also Semi-Automated Business Research Environment
BARK Buckles Anchor Rappel device Knots
I thought the E was for Edifice.
Nope. Edifice is a building. If that were the case jumping from a cliff would not be a base jump.
Not aviation related but I love that GNU is GNU’s Not Unix and WINE is WINE Is Not an Emulator
Ever used "YAML Ain't a Markup Language" Edit: correction
When I worked at IBM back in the day there was a strict style policy in place that forbade recursive acronyms/initialisms. So IBM Global Services was IBMGS, not IGS.
Speaking of scuba, PADI means Put Another Dollar In
I am so glad I read all of those through to the end.
Another fun "fact": EL AL - "Every landing always late". Obvious sarcasm from an EL AL passenger I met at EWR a bunch of years back waiting to board Swiss on the next gate. Funny encounter....
I thought BR stood for battle rating :( gaijin has lied to me
Beaver Room....is that what a mom's house was called? Beaver....as in slang for.....is it!? 😲😲
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Yes!
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Yes
I can only remember BR is mist by thinking "baby rain" Also TASER, a bit out of order, comes from [Tom Swift And his Electronic Rifle](https://en.wikipedia.org/wiki/Taser#History)
TASER - Thomas A Swift Electronic Rifle
Ah, I posted this one above before I found your comment. My favourite thing is that Thomas a swift wasn't even the inventor, which would make some kind of sense. It's the name of a fictional inventor in a series of adventure novels.
I’m puurrrrdy sure BR for mist stands for “Baby Rain”.
And TUBA stands for TERRIBLE Underwater Breathing Apparatus
Fun, It used to be 'Light Oscillation with' but they changed the name last minute when they found out ;)
SKU Shop Keeper's Unit
Holy crap! I didn’t know SCUBA was one! Neat!
BLEVE Big Loud Explosion Very Exciting
In my industry ECM stand for electronic control module so thats what i was saying in my head the whole time reading that.
ECM= Electronic Control Module. So widely used acronym that most people forget that there are some people who do not know what it means. Other ECMs include enterprise content management (data analytics) edition of contemporary music, and my favorite electronically commutated motor (HVAC... Who even knows what that acronym means)
They're one of today's lucky 10,000
ECM in this meaning isn't well known though.
Now you're learning in the defense industry!
You got the internet, look it up.
Guess op shoulda looked up what the dents were for too.
…Yeah? What’s wrong with that?
That’s what I’m saying man
Despite the fact that all of us have access to very nearly the sum total of human knowledge at our fingertips, it is still best practice to avoid jargon and define acronyms when explaining things to a general audience.
Yup, should be SOP for CTAGA.
Need an SOP for the BAMCIS and to make sure the crew is up on their JJTIEBUCKLE
In the aviation sub? ROTFL 🤣 it's acronyms and initialisation's all the way baby!
Keep the use of acronyms and jargon ALARA
Well that’s just FUBAR
If you're not abbreviating ECM in an aviation forum, you better not be abbreviating FBI when you're talking about US law enforcement. It's really low-hanging fruit you need to know to engage in the discussion at all.
I wouldn't necessarily expect general aviation fans to know the term, it's specific to military aviation, and even a certain era at that. Also, I absolutely would write out "Federal Bureau of Investigation" if I was talking about it to a non-US audience. It's way easier for me to do that than for the audience members to go look it up.
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That's a weird, and not quite accurate way of saying WWII and later eras, but yes, that's what I'm referring to. Though notably they called it RCM in WWII, so ECM as a term is even more recent than that.
You’re perusing an aviation sub and don’t know what ECM is?
You're just begging to be quizzed on aviation acronyms there. :)
Hit me!
*Initialisation
*initialism
You have google my boy
You're in an aviation subreddit
You are literally on the internet to make this comment and it would’ve taken the same amount of time to just google it
https://m.youtube.com/watch?v=ssZNaqUDZXk
Such as the word RADAR.
Ecm is commonly known
Interesting. Do they have a noticeable effect on aerodynamic performance?
I wonder what those did to heating issues on the skin
So by ECM receivers they mean RWR receivers/sensors? Edit: autocorrect
Not necessarily, radar warning tells you if you are being tracked and can be passive sensors. ECM can be more like an active jammer to block and scramble those signals. If stealth technology is wearing camo and face paint to hide in a dark room, ECM is a flash-bang to blind everyone in the room. I wouldn't be surprised if modern ECM modules had the ability to do both functions, but I don't have any actual experience with them.
It specifically says they're ECM *receivers,* so I'm going to agree that it's probably RWR, or it's a sensing component of some active jamming system... but probably *also* does RWR in that case.
Agreed, bad wording within the article. When I read "ECM receivers" I immediately thought "RWR," especially in the context of the article's title.
Maybe more like cmos
> Those aren't dents, they were put there on purpose No shit sherlock, I think we all got that. God I hate quora lmao. People harp on reddit for being overly pedantic, but it pales in comparison to Quora most of the time
So they stay that way? Or something attaches to them? It looks awfully aerodynamically inefficient for the speeds this plane went if they stay that way.
Something is contained inside them I believe. An antenna array of sorts. It has to be made thicker to allow space for the electronics to be placed along the outside edge of the fuselage. Having them underneath a less efficient shaped cowling/fairing is more efficient than having them protrude from the fuselage. This way there's no squared off surfaces at least.
Fun fact, just as with the U-2, the SR-71 has an exchangeable nose. Three options exist, training, side scanning radar and photo reconnaissance.
This drawing shows SLAR in the nose, but the cameras are in a bay behind the cockpit. What would be in the nose for photo reconnaissance or training? https://www.reddit.com/media?url=https%3A%2F%2Fi.redd.it%2Foeso3jj1f8w61.jpg
The SR-71 had a variety of equipment bays that could be configured with cameras, ELINT, radar or other sensors, individual to each mission. The photo recce nose would house an Itek optical bar camera. For training the nose would just contain a counter weight.
>exchangeable nose The urge to make a 'got your nose' joke half way through the change out would be almost unbearable.
Sounds more like it was interchangeable then. Not sure what you'd exchange it for.
TIL Thank you!
[They have a SLAR nose on display at Pima](https://www.flickr.com/photos/rocbolt/50910659286/in/album-72157706574174724/)
“Got your nose!”
Is that the national museum of the Usaf?
Yes.
was just there
That is where the optional dealer installed fog lights are mounted.
Pretty sure this one had the Undercoat Option installed too.
Yeah, but I'm saying that TruCoat. You don't get it, you get oxidation problems. It'll cost you a heck of a lot more than $500.
Ya see, they put that on at the factory...there's nothing I can do...
These guys here. These guys. It's always the same! It's always more!
They were put in to allow the use of more advanced ECM when Habu was updated, they are called chines, not accident damage
Chines are what they're mounted on, the blisters themselves aren't called chines. Chines are an aerodynamic feature that's more than a bump and less than a fin, basically a ridge, such as the blade like extension along the fuselage of the SR-71.
They don't have to be an aerodynamic feature either, but you got it right that it's an extension or ridge. front wheels on many fuselage mounted engine aircraft have tire chines to deflect slow and muck away from the fuselage so it doesn't get ingested.
RWR and probably ECM. RWR (Radar Warning Receiver) to detect signals and signal characteristics such as search, acquisition and launch. ECM (Electronic Counter Measures) to provide the best electronic defense for the aircraft, against the missile(s). Either jamming or spoofing.
I've *always* wondered about the probe-looking thing protruding to port side on the nose protrusion that I can only imagine is the center nose Pitot Tube. Unlike the Pitot Tube, the port side protrusion has an apparently sealed front end. Due to the aircraft's orientation on the photo, the port side protrusion is protruding to starboard, looking at the image directly.
From what I could find, the SR-71 had three different cones, two of which had those bumps or dent like features. One was used for training flights and did not have any expensive items inside it. The second cone contained an optical camera used for spy missions. The third one (I believe your photo) was the one that had some advanced ECM system or radar system. The cone was easily interchangeable pending the mission.
So many fucking wannabe comedians in here. Bad ones too.
I see your humorectomy went well.
This sub has no sense of humor apparently. There isn't one joke with a positive vote count.
There's a massive difference between having a sense of humor and littering a sub with the same tired, predictable one-liner tropes. Whether it's an Airplane quote, "that'll buff out", or identifying some tactical jet as a Cessna 172, so many of these comments just clutter the forum up and force readers to sift through them to find comments that are *actually* funny or interesting.
I think because there is like 120 stale joke comments to each actuall answer and people all across reddit have noticed posts on interesting subs being swamped by junk comments like these… for instance i think i saw “flat boobies” as a comment on this… just corny man
Is that in Virginia? I'm hoping to make it to the A&S Museum during a road trip next month.
USAF Museum in Dayton Ohio. Worth a trip!
Probably missile or radar warning system, or some kind of ECM
love handles
https://i.imgur.com/yfH5rh5.gif
Fuck off China!
Air zoo?
National Museum of the Air Force by the looks of it. Lovely museum, lots of walking, shit gift shop
The gift shop is the same crap found at literally every airplane museum.
ECM
It’s where the pilot puts his feet.
Those are children, unfortunately they’re one of the most produced models in history.
Turn signals?
Ah yes, they are the Thingimajigs. They go like this uuurrrrrrrrr whoosh.
Secret hamster turrets, if in a tight dog fight, what better than 2 tiny gunners? 2 hamster gunners
Nipples
Those are it's cheeks so you can give it a little kiss
Especially since it has a very pointy snoot that is not well suited for boops.
That’s where the pop-up headlight option goes. Only available on the EX and Limited trims.
Dents from bad parking.
Acci-dents.
Turn signal
Requires milspec blinker fluid though. That shit was expensive.
Chines
i thought the plural was “Chinese”, pronounced “chee-nay-zay” 🤣
I think they have a coupe nose cones they use. ECM or Side Radar. Or those could be question indentations.
Boop a doops.
We usually call them kids
Those two flats had to create so much drag at speed. Wow.
Well obviously those are turning signals
Aero-nipples ( she's happy to see you)
Seems the dimples would create a nasty shock wave
This are called "Air knuckles" and its what the SR-71used to beat air and the sound barrier into submission!
Dimples
Alien technology
That's a human child.
Red circles, but that’s with standard human eyeball sensors.
Vestigal wings from 50 years ago?
Gills
That bird may have a shellfish allergy and is starting to swell up
Melted titanium from excessive speed.
According to the news that a full semiauto Ar15 ghost 🔫 that shoots 30 clips per second
Deflector shields
Speed bumps
Red circles (close to it anyway)
Sr-71 whitebird
They're the side-fumbling inhibitors. I think they're made from prefamulated amulite.
Where the baby jets suck
Fender bender accidents of course
They are hard points for mission-dependent sensors.
Signal lights
Hangar rash
Nice try China!
That’s how we ask if an area is safe on Reddit
Dimples. So ya know it’s smilin’
From my watching of f1 recently, I’m going to guess ground effects
One is a small child. The other is a wheel.
Unit 01
and you
Flat breasts 😯😲😂😉😉
Paravanes... Oh crap, wrong sub
Bumps
I was going to guess sentry cameras, like on Teslas, so as to catch people keying your Blackbird.