I'm going to replay this from memory without googling it, just to keep the late 20th century air of some people swapping unverifiable facts in a pub: There was an old friend of my mother's, now deceased, who was a retired engineer. He claimed to be the guy who invented the 2-part tuna can, and was known for handing out end chunks of titanium castings left over from some business he ran. At any rate, he had a couple of probably 8x4 inch (wide by high) cylinders of ground quartz crystal, so flat that you could put a drop of alcohol between them and they would be inseparable if you tried to pull them apart vertically. He claimed these were from the navigation system of Polaris nuclear missiles and their navigation worked by what you'd expect: Looking at the stars and comparing them to a super accurate timestamp, plus some core memory logarithmic tables or whatever. I apologize of I've gotten any of this wrong, but he seemed legit, and again I have switched off Google for this one.
The SR-71 Blackbird Astro-Nav System worked by tracking the stars
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Re: The SR-71 Blackbird Astro-Nav System worked by tracking the stars
#102Earlier quoted context omitted.
I was working on a program that sales managers would use to divide sales territories up between salespeople and one feature was the ability to select all territories a certain distance from a point and using the most simplistic algorithm the code would crash if the circle crosses the 180 line so we had to use a somewhat more complicated algorithm than we first thought for this, even though all of the U.S. is one one…
> even though all of the U.S. is one one side of it Guam would beg to differ. :)
We didn't have Guam in our list of territories as I don't think our customers had sales offices there or if they did they already knew who was going to serve it.
Re: The SR-71 Blackbird Astro-Nav System worked by tracking the stars
#103You 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...
Re: The SR-71 Blackbird Astro-Nav System worked by tracking the stars
#104Re: The SR-71 Blackbird Astro-Nav System worked by tracking the stars
#105Earlier quoted context omitted.
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.
What kinda specialised monster engines is that plane running, holy hell.
Re: The SR-71 Blackbird Astro-Nav System worked by tracking the stars
#106Imagine what the classified systems do… ufo sighting explained I bet
Re: The SR-71 Blackbird Astro-Nav System worked by tracking the stars
#107I'm going to replay this from memory without googling it, just to keep the late 20th century air of some people swapping unverifiable facts in a pub: There was an old friend of my mother's, now deceased, who was a retired engineer. He claimed to be the guy who invented the 2-part tuna can, and was known for handing out end chunks of titanium castings left over from some business he ran. At any rate, he had a couple o…
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Re: The SR-71 Blackbird Astro-Nav System worked by tracking the stars
#108How does it see the stars? Even modern CMOS image sensors cannot see the stars during the day.
Modern, and even old, sensors absolutely can see stars during the day. It's really a question of magnification. When you magnify the image, the pixels a star falls on don't change much, but the background gets darker because the background is spread over more pixels.
I was talking to a grad student who was having an issue getting descent flat frames (images of a uniform field, used to account for dust and optical train effects). I asked why she didn't just take a picture of the sky in the daytime like most amateurs do, and she said she always ends up with stars in the image doing it that way. They tried finding the least populated part of the sky, but still always picked up stars.
Re: The SR-71 Blackbird Astro-Nav System worked by tracking the stars
#109I'm going to replay this from memory without googling it, just to keep the late 20th century air of some people swapping unverifiable facts in a pub: There was an old friend of my mother's, now deceased, who was a retired engineer. He claimed to be the guy who invented the 2-part tuna can, and was known for handing out end chunks of titanium castings left over from some business he ran. At any rate, he had a couple o…
My father worked on the guidance system for the Trident nuclear missile at Singer-Kearfott for many years and this is mostly accurate. There was a lot of geometry involved.
They used to test launch the missiles back during the cold war from submarines off of California. The missile would cross the continental US and land in the water off Florida. The Soviets would invariably send "fishing" boats to measure the tests but the coast guard would never shoo them away -- they wanted the Soviets to know just how accurate these missiles were. And they were accurate.
It blows my mind what was possible with analog tech.
Re: The SR-71 Blackbird Astro-Nav System worked by tracking the stars
#110Earlier quoted context omitted.
Former military aerospace engineer here. In my opinion it would only be worth it on long range strategic bombers such as the B-52. Fighters don't have the legs to fly far enough that celestial navigation becomes worth the added complexity. For other air mobility platforms like the C-130 or C-17 in my experience they do not include these features, as GPS, INS, and regular old "ask ATC for a vector" are usually good en…
Is one of them dead reckoning using polarized light the way bees do?
Dead reckoning using the pilot's ego as a guide.