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The SR-71 Blackbird Astro-Nav System worked by tracking the stars

theaviationgeekclub.com

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Re: The SR-71 Blackbird Astro-Nav System worked by tracking the stars

#151

Post by dmix »

jimt1234 wrote: post #103
cushychicken wrote: post #4

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

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?

Re: The SR-71 Blackbird Astro-Nav System worked by tracking the stars

#152

Post by dekhn »

cushychicken wrote: post #4

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

DEF-H is actually SCP-8737-Pi.

Re: The SR-71 Blackbird Astro-Nav System worked by tracking the stars

#153

Post by dmix »

jacquesm wrote: post #149
defrost wrote: post #116

Earlier quoted context omitted.

It astounds me that this is still a problem in 2023. I company I coded for surveyed the entire Fiji region in 1997, drafting aircraft at 80m ground clearance in long lines across both sides of the 180 longitude line. Every single bit of commercial US GIS software available at the time was garbage and failed to correctly compute line lengths that straddled the 180 longitude line, areas of rectangles that did the same,…

I'll bet if SV wasn't such a hotspot that such things would be handled better. You can't dogfood this if you're in Mountain View and chances are that the intersection of 'people working on Google Maps' and 'people that use Google Maps in Fiji' is empty.

That would make sense if Google Maps wasn't 18yrs old, but I don't really have opinions on that sort of thing as I've never worked for a large tech company on a mature product. Maybe there's not much motivation to try that hard after a certain time.

Re: The SR-71 Blackbird Astro-Nav System worked by tracking the stars

#154

Post by dmix »

ecommerceguy wrote: post #146

The B-58 Hustler was the first aircraft with stellar-inertial navigation.

That's a cool name and it looks like a pretty airplane as well (from the top at least)

https://en.wikipedia.org/wiki/Convair_B-58_Hustler?oldformat...

Re: The SR-71 Blackbird Astro-Nav System worked by tracking the stars

#155

Post by jacquesm »

junofan wrote: post #126
elzbardico wrote: post #61

Earlier quoted context omitted.

America was not critical defeating Germany. The soviets did this one.

Strange considering Jodl surrendered to Eisenhower.

But he did so in Reims (which is in France), and they later did it all over again.

Re: The SR-71 Blackbird Astro-Nav System worked by tracking the stars

#156

Post by jacquesm »

dmix wrote: post #153
jacquesm wrote: post #149

Earlier quoted context omitted.

I'll bet if SV wasn't such a hotspot that such things would be handled better. You can't dogfood this if you're in Mountain View and chances are that the intersection of 'people working on Google Maps' and 'people that use Google Maps in Fiji' is empty.

That would make sense if Google Maps wasn't 18yrs old, but I don't really have opinions on that sort of thing as I've never worked for a large tech company on a mature product. Maybe there's not much motivation to try that hard after a certain time.

Yes, I think I should have made my point better: if you can't dogfood it and the population affected is small people just don't care, especially if there is zero economic incentive. It sucks that it is like that.

Re: The SR-71 Blackbird Astro-Nav System worked by tracking the stars

#157

Post by dekhn »

blackhaz wrote: post #20
malfist wrote: post #15

When I first heard of astro-nav (for missiles) I thought it was so future sounding, like star trek. But now that I do astrophotography regularly it's just another tool that I use. It's super simple to do, I can take a photo of the night sky, and if I know the focal length and pixel size of my camera I can figure out exactly where my telescope is pointed in seconds, with an accuracy 2.5 arcseconds. You can even do it…

OK. Now please do the same with a Z-80 class CPU.

In my experience, if there was a well-defined problem in the 70s or 80s, some clever person came up with a workable solution using a tiny microprocessor with limited RAM.

The way I think about it is... when I was a kid I hated waiting at lights and imagined you could build a computer vision/ML system (this was in the '80s) that coudl recognize traffic and change the light to green when it was safe, rather than timing out. I mentioned this to some traffic engineer and he pointed out the simpler solution was to put magnetic detectors under the road and then just look for blips which are cars driving over.

Re: The SR-71 Blackbird Astro-Nav System worked by tracking the stars

#158

Post by EdwardCoffin »

EdwardDiego wrote: post #112
EdwardCoffin wrote: post #92

Earlier quoted context omitted.

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.

Re: The SR-71 Blackbird Astro-Nav System worked by tracking the stars

#159

Post by ReactiveJelly »

freyfogle wrote: post #53
_moof wrote: post #35

Earlier quoted context omitted.

The International Date Line and the 180-degree line of longitude have bitten a _lot_ of folks who don't think to test at the boundaries.

We had a great example of this in a recent Geomob London talk: ask Google Maps to route from Wairiki, Fiji (-16.8048, 179.9893) to Welagi, Fiji (-16.7349, -179.9439), two villages on the coastal road of the same island and about 10km apart, but as you can see from the coordinates on opposite sides of the anti-meridian. You get "Sorry, we could not calculate driving directions from "Wairiki, Fiji" to "Welagi, Fiji" ht…

Weird considering that Google maintains the S2 geometry lib which is supposed to handle things better than naive lat/long

Re: The SR-71 Blackbird Astro-Nav System worked by tracking the stars

#160

Post by Tommstein »

someplaceguy wrote: post #138
TheRealPomax wrote: post #119

[it] was so powerful that it could see the stars even in daylight That's a very odd thing to say: when you're at 85,000 feet (as noted, the SR-71's cruising altitude), the concept of a blue "daylight" that blocks the view of space only exists below you, not above you [1]. There is not enough Rayleigh scattering at that height to get in the way of a camera looking for stars to map to a star chart. It's pretty much why…

> when you're at 85,000 feet (as noted, the SR-71's cruising altitude), the concept of a blue "daylight" that blocks the view of space only exists below you, not above you The Astro-Nav System didn't work only at cruising altitude, it tracked stars even when the SR-71 was on the ground. [1] [1] https://airandspace.si.edu/webimages/collections/full/NAS-14...

> The Astro-Nav System didn't work only at cruising altitude, it tracked stars even when the SR-71 was on the ground. [1]

>

> [1] https://airandspace.si.edu/webimages/collections/full/NAS-14...

I don't necessarily doubt you, but linking to a 76-page PDF without any indication of where the reader is supposed to find support for your claims is not nearly as convincing as you think it is.

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