Astro Navigation
I don't own this space under my name. I should have leased it while I still could
Jimgriff, no. AP1602 the Air Almanac stopped publishing the Dec and GHA data many years ago. The UK Air Almanac. It is now reduced to tables for risings and settings and for night luminance. It is possible using ephemeris to calculate the astro data for doing a heading check etc but even 20 years ago astro was not taught at the basic nav training. Only those destined for the heavy, traditional, navigation roles - VC10, C130, Nimrod were taught astro.
FJ guys were simply taught that the sun rose in the east, set in the west, and at noon was due south. If they lost heading reference, look at the time, if it was 1100 then assume the sun bore 165 and go from there.
In the 70s, before the additional vertical stabilisers were fitted to the Nimrod it was impossible to get an astro fix with any reliability as the aircraft could experience heading changes in the order of 2 degrees during a shot and the Kolsman sextant was a pig compared with the peri-sextant.
The AP3270s series was declared obsolete in the 90s after the AP1602 ceased in 1997.
PS, AP1602 used to be an identical copy of the USN version except the latter, IIRC, had yellow pages and a plastic spiral binder. It appears the USN still produce the traditional astro tables:
The Air Almanac — Naval Oceanography Portal
FJ guys were simply taught that the sun rose in the east, set in the west, and at noon was due south. If they lost heading reference, look at the time, if it was 1100 then assume the sun bore 165 and go from there.
In the 70s, before the additional vertical stabilisers were fitted to the Nimrod it was impossible to get an astro fix with any reliability as the aircraft could experience heading changes in the order of 2 degrees during a shot and the Kolsman sextant was a pig compared with the peri-sextant.
The AP3270s series was declared obsolete in the 90s after the AP1602 ceased in 1997.
PS, AP1602 used to be an identical copy of the USN version except the latter, IIRC, had yellow pages and a plastic spiral binder. It appears the USN still produce the traditional astro tables:
The Air Almanac — Naval Oceanography Portal
Only those destined for the heavy, traditional, navigation roles - VC10, C130, Nimrod were taught astro.
After attempting to fix the aircraft's position whilst stationary on the ground at Akrotiri one autumn evening, one such astrologer eventually plotted the aircraft's position as being 500 nm due east of Moscow.....
A few brandy sours and some calculations on a bar mat a little later soon sorted that out though...
The joys of being told where you might have been some 15 minutes ago....yes, we pilots had such faith in the star-gazing antics of our directional consultants. Whereas only 5 years or so earlier, most V-bomber nav teams were pretty $hit-hot at the dark art. 'Twas said of one plotter, let's call him 'Animal' to preserve his anonymity, "He'd shoot astro taxying, if we'd let him!".
Death of Astro
Beags
Forget "Animal" - a mere plotter. I flew with an AEO who wanted to shoot the port side astro himself if it meant we'd go on GV.
PN
Got you years ago!
Forget "Animal" - a mere plotter. I flew with an AEO who wanted to shoot the port side astro himself if it meant we'd go on GV.
PN
Got you years ago!
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Is Astro Navigation taught to anyone in the armed forces any more in any way shape or form?
Thoroughly and comprehensively I expect.
Can you really imagine Naval navigators not knowing Astro? Even half decent offshore yachties do that...
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Back in the early 90's a chum and I took a yacht from Mallaig to Oban via Barra on the west coast of Scotland. Hebridean Sea was, unnaturally, as calm as a mill-pond and we had to use the iron-jib. Halfway across I noticed that the sun and moon were at right angles to each other and so the Skipper and I got the hand-held sextant out, took a couple of sightings for a sun/moon fix, bunged the results into his TI hand-held calculator, as well as the tables, and came up with a fix that put us 500 yards off track! Not bad, we thought, considering the source was 92 million miles away . . . . . . .
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Bought myself a SureShotGPS Micro today which tells me how far it is to the greens on my local golf course. People used to get awfully snaky when I pulled out the sextant and star charts to calculate how far it was before.
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Morning all!
Is Astro Navigation taught to anyone in the armed forces any more in any way shape or form?
Is Astro Navigation taught to anyone in the armed forces any more in any way shape or form?
Joint Services Sailing Centre at Gosport teach astro as an RYA sailing course.
Y_G
I don't own this space under my name. I should have leased it while I still could
AB, as a matter of interest, what tables did you use or are used. My father used Norries and haversines etc whereas we used precomputer data.
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I once took a sextant shot of Halley's Comet courtesy of some ephemeric data from the Melbourne Astronomy Centre. The Position was relatively accurate, and was confirmed by the Dual Litton - 72's that I had as a back-up.
Right hand end of the Plough/Big Dipper, four spans along and there's the North Star. What more do you need to know?!
BV
BV
TTN
Thanks BV, I'll remember that. Will be really handy if I'm ever lost in the Australian outback
Of course, if you are stuck in the outback and assuming you have a watch and can find a couple of bits of wood and nails and a protractor, you can make a quadrant and calculate your latitude using the angle of sun which works for both the northern and southern hemispheres. You basically make a quadrant with a nail at either end of the horizontal sighting arm. Point the sighting arm at the sun, looking at the shadows on the ground cast by the nails at either end. When the 2 shadows align, the sighting arm is pointing directly at the sun. Using the plumb line, read off the smaller angle of the 2 angles between the plumb line and the sighting arm and assuming the sun is directly over the equator that will be your latitude.
Of course, that is only accurate twice a year on the equinoxes so you have to compensate for the earth's tilt of 23 degrees. So depending on where you are between the equinoxes, you can calculate what proportion of the 23 degrees you need to add to your original number which should then give you a n latitude compensating for the earth's tilt.
Now if you also need to work out your longitude, assuming you have access to your radio and can pick up a World Service frequency (or any one that broadcasts the GMT pips) you can use the time difference between local noon and when you hear the pips to work out longitude. If the pips come before local noon then you are west of GMT and if they come after local noon you are east of GMT. For every 4 minutes of difference between the pips and local noon, that equates to one degree of longitude either east or west of GMT.
So there you go TTN, if you do happen to find yourself wandering round the outback, tis easy enough to work out where you are using only a McGyver-eque bit of wood and nails, protractor a radio and a watch.
The useless triv you remember from your days doing Geography!
I don't own this space under my name. I should have leased it while I still could