Astro Navigation

[jimgriff]

Morning all!
Is Astro Navigation taught to anyone in the armed forces any more in any way shape or form?

[Pontius Navigator]

Jimgriff, no. AP1602 the Air Almanac stopped publishing the Dec and GHA data many years ago. The UK Air Almanac (http://www.hmnao.com/nao/publicat/ukaa.html). 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 (http://www.usno.navy.mil/USNO/astronomical-applications/publications/air-almanac)

[Barksdale Boy]

O tempora. O mores.

[Pontius Navigator]

BB, gotcha.

[Bob Viking]

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:ok:

[BEagle]

Only those destined for the heavy, traditional, navigation roles - VC10, C130, Nimrod were taught astro.

Well, whoever taught astrology to baby VC10K navs back in around 1982 didn't always do a very good job.....

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.....:uhoh:

A few brandy sours and some calculations on a bar mat a little later soon sorted that out though...:ok:

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!".

[Pontius Navigator]

BV, you flew at night?

[Bob Viking]

Yes, but without goggles it scares the cr@p out of me!
BV:ooh:

[Barksdale Boy]

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!

[Pontius Navigator]

IK, but then you have a low post count. Newark?

[Agaricus bisporus]

Is Astro Navigation taught to anyone in the armed forces any more in any way shape or form?

Of course it is.
Thoroughly and comprehensively I expect.
Can you really imagine Naval navigators not knowing Astro? Even half decent offshore yachties do that...

[johnfairr]

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 . . . . . . .:D:D

[alisoncc]

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.

[Yeller_Gait]

Morning all!
Is Astro Navigation taught to anyone in the armed forces any more in any way shape or form?

To answer your question:

Joint Services Sailing Centre at Gosport teach astro as an RYA sailing course.

Y_G

[Pontius Navigator]

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.

[L J R]

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.:8

[Tankertrashnav]

Right hand end of the Plough/Big Dipper, four spans along and there's the North Star. What more do you need to know?!
BVhttp://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/thumbs.gif


Thanks BV, I'll remember that. Will be really handy if I'm ever lost in the Australian outback ;)

TTN

[Bob Viking]

There is some sort of cross configuration that the colonials use as an alternative but you'll have to read their flag to decifer it!
BV;)

[Melchett01]

Thanks BV, I'll remember that. Will be really handy if I'm ever lost in the Australian outback

Then you can use the Southern Cross constellation as a rough approximation of the South Pole. I think there is a star closer to the South Pole than the Southern Cross - Octantis rings bells - but it's hard to see with the naked eye so is about as much use as a chocolate fireguard for finding your way by.

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.:ok:

The useless triv you remember from your days doing Geography!

[Pontius Navigator]

a McGyver-eque bit of wood and nails, protractor a radio and a watch.:ok:

Travelling light, it would be easier carrying spare batteries for your GPS.

LOL

[Melchett01]

Travelling light, it would be easier carrying spare batteries for your GPS.

Indeed it would, but where's the fun in that? And if I were doing an impression of my old IOT instructors, GPSs would be left behind and any spare batteries you found would be the wrong size for the kit.

[BANANASBANANAS]

I remember a conversation between a certain ASCOT (VC10 C Mk 1) callsign and Jax centre when we were operating MZBZ - KIAD in the early 80's and it seemed that we were the only aircraft in the night sky.

Jax centre: "Ascot 2276 are you area nav equipped?'

Ascot 2276: "Well, we have LORAN, OMEGA and a Navigator with a sun gun."

Jax centre. "Good enough. Cleared direct ARMEL TACAN (800+ nm). Be advised RUMOURS bar is staying open pending your arrival."

Happy days.

[India Four Two]

For anyone who has more than a passing interest in astro navigation, I can thoroughly recommend Emergency Navigation by David Burch, International Marine Publishing Company, ISBN 0-87742-204-4

How to find out where you are and get where you want to go without compass, sextant or electronic instruments. This is the book you need when all else fails

[charliegolf]

Would someone remind me of the rule of thumb for using an analogue watch to locate south by the sun. (Sun, tenuous astro link!)

Something like: Point the little hand at the sun, bisect the angle between the big and little hand- voila. Is it true? Do you bisect the obtuse angle, or the reflex when more than 90? And did you need local time? Ta.

CG

[E-Spy]

Nearly right, bisect the angle between the hour hand and 12 o'clock on the watch, and you have the North-South line; depending on your hemisphere, and whether it is am or pm, you then have 50% chance of guessing correctly!

But if you have a digital watch....:{

[alfred_the_great]

Every single Officer in the RN and RFA who hold a Navigational Watch Certificate can conduct astro-nav, including sun, moon and planets in every combination required. I navigated across the Atlantic on a Warship using astro only 30 months ago. And I found the place I was going!

[Melchett01]

I navigated across the Atlantic on a Warship using astro only 30 months ago. And I found the place I was going!

But when all you have to do is turn right out of Plymouth and keep going for 3000 miles, it isn't that difficult! :E

[vecvechookattack]

Alf the Great is correct. Astro is still taught in the RN and still used to navigate with.

[Tankertrashnav]

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.http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/thumbs.gif


Knowing my luck I'd have been bitten by a Taipan or a Redback before I'd got my rig fixed up, so I think I'll continue avoiding the Lucky Country and stick to latitudes where Polaris is still visible!

Used to quite enjoy astro, but was never much good at it.

[Pontius Navigator]

But if you have a digital watch....:{

Ah but therein lies a trick. A good navigator knows where the hour hand on an analogue watch would be given the time on his digital watch so he can align a virtual hour hand and bemuse mere mortals.

And before anyone says that real navigators don't use digital watches, that may be true today with accurate quartz or radio controlled analogue models but in the 80s only a digital watch was really accurate as analogue quartz were rare.

[ExAscoteer]

IIRC Astro training was binned for Gp2 Nav studes around the time that Finningley closed and the school moved to Cranwell.

Looking at my logbook, my last Dominie flight doing Astro was 30 October 1995 (a DM19 with 434 Cse).

Shortly after this, with the introduction of the new Dominie nav/radar fit, the Gp2 (ANTS) course was re-written to include an introduction to low level maritime work and most of the high level trog-exs also disappeared.

[oxenos]

Does all this mean that the goat in the Caption Competition before last was in fact an ex R.A.F navigational G.O.A.T.?

[proudfishead]

Celestial navigation is still taught (at a very basic level) to all Royal Navy Warfare Officers. Depending upon the Navigating Officer of the vessel in which they watchkeep, they will be given further on-job training.

I certainly ensured that all Young Officers and Junior Officers' of the Watch did regular sights: morning and evening sights, sun-run-sun, moonsights etc. With practice it was more than achievable to take 5 or 6 star sights and get a position accurate to within less than a cable.

It always amused me when a student would come out with a position 4,500 nm out. It took a bit of explaining that any celestial fix will produce two possible positions. One at (or near) your actual position, and one on the corresponding opposite side of the earth.

Good times.

(Never used it in an aircraft)

[ExAscoteer]

I often think that binning Astro was a retrograde step since it gave a layer of 'belts 'n' braces'.

I remember being about 1000 miles out over the ogsplash in the early hours of a Sunday morning in the late '80's hunting a Victor 2.

Weather was punk and you could see the St Elmo's fire building on the windscreen wipers (let alone hear the increased static in the headset).

Very soon after there was an almighty bang from a lightning strike. Compasses went down, E2B was spinning like a mad thing and the CTS went down (and wouldn't reboot).

We got home based upon the Nav's ability to give us steers via the sun gun.

[Dengue_Dude]

Anyone remember Rog Howe?

The only Nav I ever saw on the Herc that didn't need the Astro stool!

He used to say he was 5ft 20.

We used to laugh on the trimotor that we had 3 navs who told us where we were rather than where we'd just been ;)

[Pontius Navigator]

ExA, there will always be times when 'obsolete' techniques are the only ones that work. One very early nav stude trip, about Ex 2 or 3, the Dominie kit went TU. We had DME and compasses and radio. Anything that needed 400Hz was unuseable.

Now the modern get-out-of-jail card is the simple "Pan Pan Pan". Instead I hoiked the stude out of the seat, quick double DME fix and set up with a manual airplot. 20 minutes, quick wind, DR ahead, heading for the entry point etc etc.

Bliss :)

[ExAscoteer]

INDEED PN!

Aaaah Manual Air Plot - the bane of Nav Studes, and terrifying to us Dominie Pilots with F all nav kit up front!

I became VERY good at rapid triple VOR fixes! ;)

[Tankertrashnav]

I remember a bunch of guys at Seletar oohing and aaahing around something one of them had spread out on a plotting table. Assuming it was the latest Playboy I went across for a look. It was the bloke's manual airplot done on a recent trip from Seletar to Gan in a Beverley.

Work of art it was !

[alisoncc]

TTN, reminds me of a trip I did in a Bubbly early '67 as SLF. It was a nav exercise from Seletar to Cocos Isles, thence to Port Hedland, Oz, and on to Alice Springs and Laverton, Melbourne. I very much doubt that they had a single external nav aid to assist, but they got there. Mind you we did spend more than a few days in the Cocos waiting parts to fix the Bubbly after she broke.

[Dan Winterland]

The calcualtions are easy now. All you need is a Texas TI86 programmable calculator and this software StarPilot-86 Calculator (http://www.starpath.com/catalog/accessories/1863.htm) Not for the purists, but it works.

[Jetex_Jim]

Celestial navigation, even robots do it,
Celestial guidance was first used (automatically) in the American Snark missile (Nortronics stellar-inertial guidance) first flown on 06/08/1953. It uses star positioning to fine-tune the accuracy of the inertial guidance system after launch.

Regarding Snark.By 1958 the celestial navigation system used by the Snark allowed its most accurate test, which appeared to fall 4 nautical miles (7.4 km) short of the target. However, this apparent failure was at least partially because the British Navigation Charts used to determine the position of Ascension Island were based on position-determination techniques less accurate than those used by the Snark. The missile landed where Ascension Island would be found if more accurate navigation methods had been used when developing the chart

Greatly disapointed to read that the charts had Ascension wrong, next thing we'll be hearing that the RAF got Australia in the wrong spot...

[Pontius Navigator]

But charting was the province of the Navy. The Navy would say where Ascension was and then the RAF would photograph it and the RE would map it.

[alfred_the_great]

Madeira to Bermuda is a little more difficult than Guzz to the East Coast! Not much I'll grant you, but get the DR wrong by more than 30 miles and you're in the poo!

[Canadian Break]

Can any of you brilliant chaps out there tell me how to calculate by how many minutes sunset is delayed for every degree west you go ( in the northern hemisphere)?

[Fareastdriver]

Depends on how far North (or South) you are. In summer when near the poles the sunset is delayed for weeks.

[Melchett01]

Canadian Break,

Have a look here Variation in Time of Sunrise (http://www.physics.rutgers.edu/~twatts/sunrise/sunrise.html)

It covers both sunrise and sunset, but you might want to get a strong coffee before you start reading though :ok:

[Tankertrashnav]

Have a look here Variation in Time of Sunrise (http://www.physics.rutgers.edu/~twatts/sunrise/sunrise.html)



Yeah, exactly, that's just how I'd have put it!

:confused: :confused: :confused:

[Smoketoomuch]

"how many minutes sunset is delayed for every degree west you go "

Err, isn't it simply derived from minutes in a day divided by 360
ie; 11540/360
=4

ie sunset is delayed 4 mins/degree west.

Latitude is irrelevant to the affect of purely westerly travel. OK you might not get a sunset in some places, but the sun will still appear to travel at 1 degree every 4 mins.

Or have a made some stupid gaff and should I delete this post to avoid deep personal shame?

[Pontius Navigator]

Smoke, I'm with you.

The best examples, or should I say experiences, come on crise ships. Leaving Southampton and arriving Dublin 2 days later one enjoys a few extra minutes of daylight.

Sunset is always 4 minutes later for every degree of longitude that one travels west at the same latitude. If you moved west and also changed your latitude then sunset time would change by both longitude transport and also by sun altitude for latitude change.

[Shackman]

But charting was the province of the Navy. The Navy would say where Ascension was and then the RAF would photograph it and the RE would map it.

PN - you forgot the last bit - 'Then the navy would run into it!'

It was astro nav - or rather using the astro compass one evening - that allowed Frank E.... to prove that Gan was actually 1 mile South of the Equator rather than 1 mile North (or maybe the other way round). The position had remained 'as was' since the Navy had first plotted it and then used it as their secret 'Port T'.

Certainly remember having to learn to do Manual Air Plot during MOTU as a pilot (we were supposed to know how to do every other role in the ac), and still find I use some of the elements of that instruction whilst discussing nav at DHFS.

At least I'll never again hear those dreaded words 'Steady for Astro' whilst flying at low level in gale force winds!

[Herod]

Don't forget that when using a watch, it must be on local time, not daylight saving. Always a fun few minutes when visiting a stately home in summer. Stand near the sundial and listen to people explaining to one another why the time is an hour out. :ok:

[Canadian Break]

Thank you gentlemen, one and all!

[dagama]

...and then there was the late Geoff Bashford, who was 5 ft nothing. Not only did he need the Astro stool at its max height but he tip-toed to reach the eye-piece. AND the eye-piece was at the lowest point! Can't imagine Geoff doing a 2-minute shot while maintaining the 'tip-toe' posture. A fine nav instructor and a true gentleman.

[teeteringhead]

Stand near the sundial and listen to people explaining to one another why the time is an hour out. .... rarely and only coincidentally would it be exactly an hour out.

You must also consider arc to time for the real local time and also the Equation of Time, as "Mean Time" is only a convenient average. (There's a clue in the name!)

[Fareastdriver]

"Mean Time"

At the beginning of the 19th century the village vicar was responsible for the time. He would track the sun and keep the church clock set to the local time which would vary across the UK. When the railways came along then a common (Mean Time) was set so that the trains arrived and departed to a common clock. They could then keep track on how late they were.