BlueSkyNick
Active member
Bilbo, with reference to your post timed 1950 please complete the following sentence in no more than 15 words:
"What I am really trying to say is ...
"What I am really trying to say is ...
Use of a Sextant
- Thread starter BlueSkyNick
- Start date
bilbobaggins
N/A
My dear Auld Nick, thank you for your expressed concern.
Kindly let me reiterate....
[ QUOTE ]
I'd really like some well-informed opinion on a wee technical matter.....
[/ QUOTE ]
As to your specific request regarding "What I am really trying to say is ....", were I rather less of a gentleman I might be tempted to suggest "....away an' bile yer heid, ye glaikit great tumshie!"
/forums/images/graemlins/laugh.gif
Kindly let me reiterate....
[ QUOTE ]
I'd really like some well-informed opinion on a wee technical matter.....
[/ QUOTE ]
As to your specific request regarding "What I am really trying to say is ....", were I rather less of a gentleman I might be tempted to suggest "....away an' bile yer heid, ye glaikit great tumshie!"
/forums/images/graemlins/laugh.gif
Sixpence
Active member
There was me hoping for some helpful comments and the best so far has been chuck it in a cupboard /forums/images/graemlins/frown.gif ah well , BigNick , better luck next time
iangrant
New member
You need the Tome quick noon sight system.
Worked for me - no sextant now but had great fun doing the sights on passage.
Worked for me - no sextant now but had great fun doing the sights on passage.
BlueSkyNick
Active member
well at least its proved I don't need to rush out and spend a load of money - well, on a sextant anyway !!
Sixpence
Active member
I suppose that's one saving anyway , I wonder if the same applies to all the other bits and pieces we thought about buying but hadn't got round to yet
G
Guest
Guest
MN answer to Bilbo ... (well what I was used to !!)
Rn as you describe ????? Blimey !!
MN - morning / noon sights usually done by 3rd and 2nd Mates with cadets if on board. Averaged pos. lines of each person plotted for each set of sights. Noon mer-pass was agreed by all after reading vernier / micrometer. Then corrected and plotted.
2nd mate usually did the run up of morning lines to noon.
Stars - usually Chief Mate or whoever was detaile for 4-8 watch ... and usually done alone or maybe with 1 or 2 cadets - but separate.
Most used Air Nav tables and the 6 selected stars ... actually often selecting 3 spread round horizon and 2 shots of each taken ... It was usual to work round horizon as twilight deepened .... starting in east and finishing up in west.
The days of pure sextant work without Air tables for years had died off really ... why work so hard at it when Air tables helped so well.
THis bringing back memories of : 1 banana ... 2 banana .... 3 banana .... etc !!
Of course those in the air had the Bubble Sextant ... so horizon was not the issue as was on a ship !! My father had a Bubble job at home for years ... I think my Brother also has that in his collection !!
My Father bringing a B-17 across from canada to UK ...
The B-17 ...
Rn as you describe ????? Blimey !!
MN - morning / noon sights usually done by 3rd and 2nd Mates with cadets if on board. Averaged pos. lines of each person plotted for each set of sights. Noon mer-pass was agreed by all after reading vernier / micrometer. Then corrected and plotted.
2nd mate usually did the run up of morning lines to noon.
Stars - usually Chief Mate or whoever was detaile for 4-8 watch ... and usually done alone or maybe with 1 or 2 cadets - but separate.
Most used Air Nav tables and the 6 selected stars ... actually often selecting 3 spread round horizon and 2 shots of each taken ... It was usual to work round horizon as twilight deepened .... starting in east and finishing up in west.
The days of pure sextant work without Air tables for years had died off really ... why work so hard at it when Air tables helped so well.
THis bringing back memories of : 1 banana ... 2 banana .... 3 banana .... etc !!
Of course those in the air had the Bubble Sextant ... so horizon was not the issue as was on a ship !! My father had a Bubble job at home for years ... I think my Brother also has that in his collection !!
My Father bringing a B-17 across from canada to UK ...
The B-17 ...
bilbobaggins
N/A
Re: MN answer to Bilbo ... (well what I was used to !!)
Those recollections and photos are fascinating, Nigel. Of course, the Air Tables made the job so much easier and quicker - I cannot understand the RYA insistence on still using the Nautical Almanac, in the Shorebased Ocean course, when the Air Almanac is faster, cheaper and less prone to error. It must be a hangover from Cdr Bill Anderson.....
The development of trans-ocean air navigation - Imperial Airways and the Empire class flying boats.....
...required astro-navigation, which developed considerably from the sound base of maritime practice. Different companies and RAF Commands had differing required fixing techniques and work-cycles. Many required the '3-star fix' about every half-an-hour; others preferred the '2-star sandwich fix' every 20 minutes.....
The V-Force had several special techniques all of their own. The heart of a Vulcan's nav fit was, for many years, an automatic DR machine fed from a Master Reference Gyro Unit and a Heading Reference Unit ( the main steering compass ). The aircraft flew pre-planned tracks at high level, and the kit was typically set up oriented Along and Across Track, rather than around Lat and Long. Output was fed to the autopilot, giving 'fly left' and 'fly right' signals, as well as Distance To Go to the next waypoint/turnpoint.
All gyros drift, and a principal job was providing correction inputs to the system, based on the astro intercepts, as error signals resolved into Along and Across Track Errors. So one would choose stars that were, respectively, 'ahead or astern' and 'out on the beam'. The nav procedure would be to shoot a 'beam star' with the periscopic pendulous reference sextant ( a 2-minute averaging device gave the equivalent of 60 sights on the body ), then work out the Across Track Error as a gyro drift rate, input that, and monitor the autopilot commanding a heading change to converge onto Track.
Then one would do much the same on an 'ahead or astern' star, inputting the Along Track Error, and adjusting the Time To Go from that.
This procedure is called 'Fix Monitored Azimuth', and in the hands of a practiced crew, was very highly accurate. The US Air Force did much the same in their B-52s, but they developed an automated 'star tracker' which permitted astro-fixing to continue even in daylight. The system survived into the B-1 'Lancer'.
In NATO competitions, the V-Force entrants regularly beat the Yanks into second or third place - something that was a bone of contention for many years - due to their repeated precision navigation, reflected in their bombing results.
Today, we are dependent on GPS.
/forums/images/graemlins/wink.gif
Those recollections and photos are fascinating, Nigel. Of course, the Air Tables made the job so much easier and quicker - I cannot understand the RYA insistence on still using the Nautical Almanac, in the Shorebased Ocean course, when the Air Almanac is faster, cheaper and less prone to error. It must be a hangover from Cdr Bill Anderson.....
The development of trans-ocean air navigation - Imperial Airways and the Empire class flying boats.....
...required astro-navigation, which developed considerably from the sound base of maritime practice. Different companies and RAF Commands had differing required fixing techniques and work-cycles. Many required the '3-star fix' about every half-an-hour; others preferred the '2-star sandwich fix' every 20 minutes.....
The V-Force had several special techniques all of their own. The heart of a Vulcan's nav fit was, for many years, an automatic DR machine fed from a Master Reference Gyro Unit and a Heading Reference Unit ( the main steering compass ). The aircraft flew pre-planned tracks at high level, and the kit was typically set up oriented Along and Across Track, rather than around Lat and Long. Output was fed to the autopilot, giving 'fly left' and 'fly right' signals, as well as Distance To Go to the next waypoint/turnpoint.
All gyros drift, and a principal job was providing correction inputs to the system, based on the astro intercepts, as error signals resolved into Along and Across Track Errors. So one would choose stars that were, respectively, 'ahead or astern' and 'out on the beam'. The nav procedure would be to shoot a 'beam star' with the periscopic pendulous reference sextant ( a 2-minute averaging device gave the equivalent of 60 sights on the body ), then work out the Across Track Error as a gyro drift rate, input that, and monitor the autopilot commanding a heading change to converge onto Track.
Then one would do much the same on an 'ahead or astern' star, inputting the Along Track Error, and adjusting the Time To Go from that.
This procedure is called 'Fix Monitored Azimuth', and in the hands of a practiced crew, was very highly accurate. The US Air Force did much the same in their B-52s, but they developed an automated 'star tracker' which permitted astro-fixing to continue even in daylight. The system survived into the B-1 'Lancer'.
In NATO competitions, the V-Force entrants regularly beat the Yanks into second or third place - something that was a bone of contention for many years - due to their repeated precision navigation, reflected in their bombing results.
Today, we are dependent on GPS.
/forums/images/graemlins/wink.gif
Koeketiene
Well-known member
Re: MN answer to Bilbo ... (well what I was used to !!)
[ QUOTE ]
In NATO competitions, the V-Force entrants regularly beat the Yanks into second or third place - something that was a bone of contention for many years - due to their repeated precision navigation, reflected in their bombing results.
Today, we are dependent on GPS.
[/ QUOTE ]
And the Yanks still get it wrong - friendly /forums/images/graemlins/confused.gif fire anyone?
[ QUOTE ]
In NATO competitions, the V-Force entrants regularly beat the Yanks into second or third place - something that was a bone of contention for many years - due to their repeated precision navigation, reflected in their bombing results.
Today, we are dependent on GPS.
[/ QUOTE ]
And the Yanks still get it wrong - friendly /forums/images/graemlins/confused.gif fire anyone?
