US Navy makes an amazing discovery in the field of navigation ..

[ricardian]

Who needs GPS anyway?

[G-CPTN]

How do you read a sextant in thick fog?

[ExSp33db1rd]

How do you read a sextant in thick fog?

Obviously you can't, climb above it or use LORAN.

Describing my navigation experience not so long ago, a young aero club student said " What's a sextant ? " One could weep, but it led me to giving a talk about "Navigation before GPS " Radio Range, NDB, VOR, Consol, Loran, Astro, Grid Nav. over the Pole etc. They seemed to be interested, but I had to resort to Google to remind myself about Astro calculations ! 707 had a periscopic sextant, pushed up through the roof via a pressure retaining housing. Stewardesses would often ask what one could see, so were invited to come back later, by which time we had applied the residue from a burnt cork around the rubber eyepiece. Saying they couldn't see anything they were told to press harder, then try the other eye. Then they walked back through the cabin ! Such fun.

The early 747's had the sextant housing, but by then INS had taken over, sp a navigator was no longer carried, but the housing was retained and designated as a smoke removal port, should it be necessary.

[TheGreenGoblin]

Who needs GPS anyway?

Interesting article. As it implies, the most secure navigational systems will rely on a multiple navigational methods, each cross checking the other with error correction/dropping algorithms to correct or exclude jammed, compromised or unavailable position data. Methinks low cost INS systems will become generally available, even to the general public, in the near future.

The GPS system is very open to spoofing but it is also reasonably simple to locate and eradicate spoofers as well (in a battle environment/space anyway).

[TheGreenGoblin]

Low cost navigation systems

[unifoxos]

So the article says that this system is to be certain of getting a fix if the GPS satellites are knocked out - then it relies on satellites???

QUOTE "this new approach takes readings from human-made satellites rather than stars,"

[TheGreenGoblin]

So the article says that this system is to be certain of getting a fix if the GPS satellites are knocked out - then it relies on satellites???

QUOTE "this new approach takes readings from human-made satellites rather than stars,"

They are talking about using the whole constellation of satellites, not just GPS satellites and to take fixes on the positions of X+3 of these satellites in LEO to determine a position without needing to use a GPS signal. Such a scheme would require a very accurate clock, a database of known satellite orbits and ability to the determine the distance and angle of the satellite above the azimuth (probably using very sensitive light sensors/and or lasers).

[Pontius Navigator]

Who needs GPS anyway?

And the classic silhouette on the first image is wrong. You need to scroll down to see the proper trig setup.

[1DC]

My sextant is on standby under my desk as I write. My grandson has already asked me if I will leave it to him in my will..

[Ex-Ascot]

We used the sextant mounting on the Andover and the VC10 to fly standards. Had to fly personal standard of principle pax and the host country standard. You shoved them up together on a twin pole then twisted the base and the poles split into a 'V'. Only ever once experienced a take off with flags flying. They don't much like it after V2. Flags go flying off and the poles bend. I used to add them into my personal pre-take off and after landing checks.