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Comment by cushychicken | Hacker News Reader

You can see one of these up close - both the device, and the airplane! - at the Evergreen Aerospace Museum in McMinnville, OR.

They also have on display another Blackbird payload labeled DEF-H. It’s a nondescript white box which you are allowed to look at, but not allowed to know what it does. XD

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I got to see an SR-71 on display in New York several years ago. What really struck me was how BIG it was, seeing pictures of it doesn't really give you sense of scale, it was a massive plane.

Even more impressive seeing it sweat fuel onto the apron in the afternoon sun for a few hours then engine ignition with Chevy V8 start cart, takeoff followed by low level transonic flyby.

Fairford IAT 1989.

Weren’t those big blocks on the starter cart Buicks?

They were initially Buicks, then Chevy later on [1]

[1] https://www.thesr71blackbird.com/Aircraft/Engines/starting-t...

That was a great read, thank you. TIL about TEB, and how at one point they were investigating coal slurry as a fuel? (Although tbh that sounds like someone having fun on Wikipedia).

You can hear the starter cart in some of the YouTube videos, like this one: https://www.youtube.com/watch?v=nFO--wzFfUs - it really gets going around the two minute mark.

What kinda specialised monster engines is that plane running, holy hell.

The fuel doesn't ignite at "low" temperatures, one reason is because the whole airplane leaks fuel until it's at an high enough speed. At that point, maybe because of the surface temperature, or the forces it tackles at Mach 3+, the whole thing becomes airtight.

At least, that's what I remember.

Yup, at Mach 3+ the fuselage expands so significantly that gaps need to exist when it’s stationary, otherwise it’d buckle. So the gaps mean it leaks fuel when stationary.

It's not supposed to leak. It just that the sealant to bridge the gaps wasn't perfect, so it'd get some leaks through the sealant.

What’s more, at its highest speeds, the engine transitioned from conventional turbojet to mostly ramjet compression by extending/retracting a nose cone within each engine intake. Doing so moved the bow shockwave of the cone so that it reflected inside the engine intake, which had the effect of slowing the Mach 3 air down to subsonic speeds so it could be used for engine combustion. But even still, energies were so high that almost all the thrust came from afterburning - the engine combustion stages were basically just spinning as air went through them.

The whole plane is an engineering tour-de-force, especially considering it was designed with slide rules

As I read it, not just one v8 but two, with straight pipes:

https://www.thesr71blackbird.com/Aircraft/Engines/starting-t...

The DEF-H module contains the Diesel Exhaust Fluid for the truck.

Not sure you are were trying to be serious or not, but the DEF-H was one of the defensive systems used to jam surface to air threats. The system had two "modules" with one in the left and one in the right chine.

You can get close enough to touch (but you mustn’t touch) the SR71 at the Udvar-Hazy center of the Smithsonian!

You can also get close to an SR-71 at the Robins Air Force Base museum in Georgia, and if you touched it probably nobody would notice

There's also one at the March air field museum (attached to March ARB, née March AFB) in Riverside, California.

Theres one at Strategic Air Command Museum in Nebraska.

https://www.sacmuseum.org/what-to-see/aircraft/sr-71a-blackb...

I've visited that one. As a someone who grew up during the Cold War, the idea that we've got these once super-secret military aircraft just sitting where any old tourist can walk up and take picture from a few feet away always generates some cognitive dissonance.

In Palmdale California, at the corner of 25th St E & E Palmdale Ave [1], there's what is essentially a parking lot with a chain link fence around it. Sitting there are a SR-71, a A-12, a D-21 (supersonic recon drone originally launched from A-12 variant), and a U-2. You can just sit there and take all the pictures you want.

[1] https://www.google.com/maps/@34.6026576,-118.0860601,117m/da...

When I was in Boy Scouts we had a camping trip to SAC. A snow storm forced us to relocate inside and the Air Force came up with the museum as our temporary sleeping area. I got to sleep about 20 feet away from that SR-71. I will never forget how cool that was.

The important fact is missing - can you touch it?

I have definitely touched the SR-71 at the Evergreen museum in Oregon.

I'd feel more ok with touching an SR-71 at an AFB or the Evergreen museum, but the SMITHSONIAN? Never! :)

Was it rough or smooth? It looked smooth but I wonder if it felt rough!

There's an A-12, the CIA version of the Blackbird, on the deck of the USS Intrepid, in New York. It is indeed a very large aircraft!

(I was also impressed by how many aircraft could fit on an aircraft carrier. There was also a Concorde!)

I was in NYC for the first time a few months ago in Hell's Kitchen. Looked out of the window from the top floor of a loft we were in and could see the USS Intrepid out the window. I wish I would have realized this sooner.

Don't forget the Space Shuttle Enterprise complete with its own separate pavilion; aircraft carriers are indeed ginormous, and that's just an ancient WWII model: https://www.intrepidmuseum.org/Space_Shuttle_Pavilion.aspx

I forgot about it, and yeah, the Space Shuttle itself is pretty big and impressive. So this makes the size of the aircraft carrier even more amazing.

For anyone thinking about going (highly recommended, it's a great museum) the Concorde is currently elsewhere for maintenance. It's supposed to be back early next year.

There's an A-12 Blackbird at the San Diego Air & Space Museum in Balboa Park. Not an expert, but my understanding is the A-12 was basically the beta version that eventually lead to the SR-71.

https://sandiegoairandspace.org/collection/item/lockheed-a-1...

That looks a bit smaller than I expected, from my uninformed opinion. Maybe it's just the angle of the photos.

How did it fly for 10hrs (based on the parent article) at high speeds without a ton of space for fuel?

Lots of aerial refueling. 10 hours in the air, yes, but not on a single tank of fuel.

"The SR-71 needed to be able to fix its position within 1,885 feet (575 m) and within 300 ft (91 m) of the center of its flight path while traveling at high speeds for up to ten hours in the air."

They refueled in-flight, and the high speeds they are referring to probably weren't sustained for 10 hours... I think it is more like "while traveling at high speeds and for up to ten hours"...

The SR-71 is smaller than you'd think ([edit] to my eyeballs, at least).

As far as fuel goes (a) in a three-dimensional object, "volume adds up fast," and (b) aerial refueling.

(p.s. My dad was a US Navy pilot in the early 60s when celestial navigation was still core curricula.)

The A-12 was the original single seat version developed for the CIA. But eventually the Air-Force was given all responsibility over the planes and they re-designated the plane and added a second seat to fit their pilot philosophy.

There were supposed to be more variants, even tactical bombers but military politics and budget constraints and yadda yadda yadda.

The Air Force museum in Dayton has a YF-12, which was the prototype of the interceptor variant. It's readily distinguishable from the A-12 and SR-71 because the chines don't extend to the front of the nose. This so that the nose cone could be made of material that is transparent to radar.

It's a fantastic museum, because they not only have this, but the Spruce Goose, the largest wooden airplane ever built (and it is massive)! https://www.evergreenmuseum.org/exhibit/the-spruce-goose/

Per this[0] it seems like a radar jammer, however details, like you mention, are classified.

[0] http://www.sr71.us/sr_sensors_pg3.htm

You can - and this is almost as interesting - go down a waterslide from a 747 hanging from the ceiling!

There are a lot of these on display it seems. The one we saw was on display was at the SAC museum outside of Omaha.

The SAC Museum Wikipedia page links to the website page on this craft: https://en.wikipedia.org/wiki/Strategic_Air_Command_%26_Aero... https://www.sacmuseum.org/what-to-see/aircraft/sr-71a-blackb...

Quantum navigation systems could also determines position from quasi-stable astral signal sources FWIU. https://news.ycombinator.com/item?id=36222625

Sunstone: https://en.wikipedia.org/wiki/Sunstone_(medieval)

Amplituhedra and cost of calculation: https://en.wikipedia.org/wiki/Amplituhedron

There's another one in the Museum of Flight in Seattle.

The Museum of Flight has an M-21 - in the Blackbird family but a few feet shorter than the SR-71. It's a truly wonderful plane and I love that you can walk underneath it and get right up close. As I recall they also have one of the engines pulled out to look at as well.

The Museum of Flight also has an entire SR-71 cockpit (salvaged from a crash) that visitors can sit in. It's the only place I know of in the world where regular people are encouraged to touch one.

I'm guessing the DEF-H was some kind of electronic countermeasure jamming device, a newer version of this "Def B": https://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird#/medi...

Come on, everyone knows what the DEF-H was. It was the replacement for the DEF-F.

(The real question being, of course, what is the DEF-G?)

You’re joking, but it’s predecessor was actually DEF-F.

There aren’t many details but it’s some kind of electronic countermeasures/data collection system.

See the museum exhibit here:

http://www.sr71.us/sr_sensors_pg3.htm

I'm not much into planes, in particular, but that museum is really cool.

Not even, say, if you showed up with x-ray goggles? (Or whatever the modern feasible equivalent it?)

Had the plane as a wall to wall poster as a kid. And now finding out its next door! Super excited.

Really? Thanks! I did not know this and I've wanted to see the Blackbird up close!

DEF-H is actually SCP-8737-Pi.

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