Celestial navigation and Machado's five questions

[beasly]

Beasly, your questions are very fundemental, reminiscent of introducing a new student to an E6B for the first time.

...

Fundamental's are where it is at.

Beasly, with his CFI, CFII, MEI , etc is a student. No egos in my aircraft.

The E6B is the a wonderful example human thought wrought in metal. I love that tool.

Thanks for replying.

 

[beasly]

As you predict, not all stars are visible to every location on the Earth. Example, the "Southern Cross" is not visible in the N hemisphere. Sometimes when transiting the equator but not in the higher latitudes.

One sure fire way to locate Polaris is by way of Ursa Major (Big Dipper). Most everyone can recognize the Big Dipper and because it's so prominent in the sky, it is easy to find. The outside two stars which form the 'cup' form a pointer to Polaris. Not precisely throughout the year but close enough.

This time of year, overhead and a bit east at approx. 30* North latitude, is Pegasus constellation. Find that to locate other stars and constellations. Constellations are also used as reference for locating planets in transit.

So, it looks like "time" and "place" are linked.

I (on Earth) cannot know where I am unless (in rough terms--season) what time it is.


Just from this conversation, it seems evident that as time becomes more exact--from seasons to days to hours to minutes to seconds--so knowing ones position becomes more exact.

If that is a correct statement, then that is a very important fundamental.


FWIW, the impetus of my original post was the navy midshipman who won the Nobel prize for determining the speed of light--back in the 1920's

Those guys could flat out THINK!

 

[RICHARD5]

I too love the metal E6B. It's one of my most cherished possessions. I like discovering the relationships of different values on the scales. And I haven't lost yet, I can solve on my whiz wheel faster than someone using the electronic version. If I lose my place I just go back to the last step. And it's one handed, cordless, never needs batteries. I toss it in the back seat and pick it up where I left off. I take it with me on road trips to plan my ETA, elapsed time, fuel burn, etc.

The electron burning E6B doesn't show the relationships as well.


Many moons ago a Navy man gave me many sheets of the plotters he used. So frigging cool, and as much as I love charts, it was a hell of a lot better than plotting LOPs on the chart, course made good, etc. I was hooked.

Basically a star chart is a road map of the night sky. It's very useful even in amatuer astronomy. There are pocket sized laminated charts and there are the sky charts 2x the size of dinner place maps or larger. Some have the major navigation stars which glow in the dark. Some have lines connecting the stars to help the user navigate the constellations. All are basically a primer to familiarize you with the celestial bodies. Barnes & Noble or any bookstore larger than the mom & pop would have one. Or just go online and survey the results before purchasing. I imagine a 18" square laminated in color would be $20 or less.

My F-I-L flew B-25s in WWII. I have his nav tools. I also have some earlier models of the circular slide rule from a friend who flew before WWII. I don't pull them out often so I forget the mil spec on them but they are danged cool.

 

[RICHARD5]

So, it looks like "time" and "place" are linked.

I (on Earth) cannot know where I am unless (in rough terms--season) what time it is.


Just from this conversation, it seems evident that as time becomes more exact--from seasons to days to hours to minutes to seconds--so knowing ones position becomes more exact.

If that is a correct statement, then that is a very important fundamental.


FWIW, the impetus of my original post was the navy midshipman who won the Nobel prize for determining the speed of light--back in the 1920's

Those guys could flat out THINK!

Every navigation system works on this principal. From OMEGA, LORAN-A, to GPS. It's got to be. It IS a very fundamental principle.

We ride on the shoulders of giants.

 

[fish314]

Hey Richard,

What kind of accuracy could you get off of cel nav? I was a copilot in the KC-135 before all of the avionics modifications made cel nav obsolete, and I think "passing" for the new navigators on their check rides was something like +/- 30 miles of the actual position IIRC. I got the sense that the instructors could do quite a bit better than that... but then it went away very shortly after I got to the squadron... replaced by GPS.

Oh, this was Feb. 2000 or so, btw.

 

[granlistillo]

If you use altitude-intercept, which as I understand it is the most accurate version, you need a good clock, too.

Intercept method has more to do with type of sextant than accuracy. Using a periscopic sextant you have to have an assumed position to compare to an observed position or "shot". In other words if you don't calculate the azimuth of star and the height you would never find it with a periscopic sextant. You compared the height observed with the height calculated and determine whether you move your LOP towards your DR position or away along the azimuth of the body.

Hey Richard,

What kind of accuracy could you get off of cel nav? I was a copilot in the KC-135 before all of the avionics modifications made cel nav obsolete, and I think "passing" for the new navigators on their check rides was something like +/- 30 miles of the actual position IIRC. I got the sense that the instructors could do quite a bit better than that... but then it went away very shortly after I got to the squadron... replaced by GPS.

Oh, this was Feb. 2000 or so, btw.

UNT in 1993 10 miles +- from INS position and that was generous. A three star fix done properly were often with three miles or dead on.

You maybe thinking about the clearance. There was something called celnav clearance given by ATC where the aircraft would have a 30 mile corridor. It would take a minimum of 30 minutes to fix and the aircraft would be flying in a heading until the fix could be resolved and winds calculated from the no "wind plot". Each observation takes two minutes each side of the fix time. A sunline was shot or observed a minute before to a minute after, and as a single LOP would only give you an EP estimated position. It would take less time than fix where you would have to spend at least 6 minutes on 3 stars (or planets/moon).

In shorter words Celnav fixes can be fairly accurate if the autopilot is on, or you have a very steady hand flying in low turbulence. However the length of time to precalculate, shoot, resolve fixes, calculate new headings would need a wider corridor.

 

[Orange Anchor]

Hey Richard,

What kind of accuracy could you get off of cel nav? I was a copilot in the KC-135 before all of the avionics modifications made cel nav obsolete, and I think "passing" for the new navigators on their check rides was something like +/- 30 miles of the actual position IIRC.

The average navs would be close. And a good nav with a good boom taking shots would have you right on course. And too, you had to be able to see the stars.

Also, the navs had to be able to direct an ARDA or airborne radar directed approach. The good ones would have you lined up precisely with the runway.
http://www.avweb.com/news/system/183199-1.html The ARDAs were like ASRs and some where better at it than others.

Looking back, it is a wonder we found our way anywhere. Many times the Boom was the oldest guy on the crew and he was in his 30s. I was fortunate to have one OLD boom who started out as a waist gunner on a B-17.

 

[fish314]

The average navs would be close. And a good nav with a good boom taking shots would have you right on course. And too, you had to be able to see the stars.

Also, the navs had to be able to direct an ARDA or airborne radar directed approach. The good ones would have you lined up precisely with the runway.
http://www.avweb.com/news/system/183199-1.html The ARDAs were like ASRs and some where better at it than others.

Looking back, it is a wonder we found our way anywhere. Many times the Boom was the oldest guy on the crew and he was in his 30s. I was fortunate to have one OLD boom who started out as a waist gunner on a B-17.

I've actually done 1 ARDA also, but it was at Altus... not much to shoot at out there, though, and it was a student nav doing the ARDA. We basically just followed the VOR course.

 

[Autothrust Blue]

Looking back, it is a wonder we found our way anywhere.

I sit in the 182T, with dual WAAS-equipped GPS receivers, dual this, dual that, and a rather precise heading reference system, and am amazed that those who came before me crossed oceans with whiskey compasses and stopwatches.

While those methods are now obsolete, they still work - and I too want to know how to do it, for novelty's sake. My comment about the A346 having an astrodome was massive as one never knows when l'computer will start having a bad day...

 

[Jwscud]

Celestial Nav is good fun - I do it for a living when deep sea.

On a point of order, it is possible to find your latitude and longitude without an accurate chronometer, but it requires lunar observations and reduction tables that aren't published commercially any more. Lunar distance observations use the principle that the position of the moon relative to the sun and stars is the same anywhere in the world at any given time; measure the angle and compare it to tabulated values and you know the UTC. Compare that to your local time (which can be obtained from a 'time sight' around local noon) and you have your longitude. Accurate enough for deep sea navigation on a ship, obviously not relevant to aircraft.

Celestial navigation is a big part of the syllabus for seafaring qualifications still; my day job involves navigating large tankers around the world and when deep sea we still take several sights daily. Superintendents and Surveyors (think the seagoing version of the FAA Inspector) will want to see your workings from sights you took on passage.

I find different navigational methods absolutely fascinating and am a bit of a geek for this sort of thing.

 

[Orange Anchor]

I sit in the 182T, with dual WAAS-equipped GPS receivers, dual this, dual that, and a rather precise heading reference system,

A while back I did some work for an SR22 outfit and I am amazed at how much they have put in that machine. But one thing I frequently saw was a huge reliance on the boxes for EVERYTHING. We were north of our field on a blue sky day and after maneuvers I said let's RTB. The guy began programming the GarminS. I knew what he was doing but asked if he ever used the big situation indication... called a WINDOW. He looked at me blankly.

The other issue was the information was presented in such a colorful way that it was easy to understand how someone who grew up on a MAC or with Windows just saw it as a moving video game. Again, not good as once stuff started going down, some guys were completely lost.

I have a small handheld Garmin I use in my Swift and I confess it is very easy to sit back and let the Garmin do the work. BUT some days, it is very enjoyable to get out the charts and just move your finger along the chart verifying where you are and what time your next point will arrive.

 

[Orange Anchor]

Celestial navigation is a big part of the syllabus for seafaring qualifications still; my day job involves navigating large tankers around the world and when deep sea we still take several sights daily. Superintendents and Surveyors (think the seagoing version of the FAA Inspector) will want to see your workings from sights you took on passage.

I find different navigational methods absolutely fascinating and am a bit of a geek for this sort of thing.

I was not aware that there are differences between chronographs and chronometers until I took my Omega in for calibration. It got me to reading and I also found that the GPS time is :15 seconds ahead of GMT. And that people who maintain watches, time pieces etc are horologists, or people concerned with horology, the measure of time.

And the Omega? It is a chronograph and the accuracy standard is +/- about 2 minutes a day. And this is the watch they went to the moon with.

 

[MikeD]

I briefly taught the JAA residence Radio NAV and Navigation units and they do not have to know cel nav. They had some local apparent noon questions, and some time conversion probs but nothing even close to cel nav.


I think they taught cel in UNT until around 2000. I went through IUNT in 93 and it was mostly radar and cel stuff. I had to shoot a sun line or a star fix on every mission when I was on the Nav table. When I got to the squadron there some of the planes had non integrated GPS installations others not. On one bird with a faulty Air Data computer input that made the OMEGA worthless I had to update the INS on a three star fix... Other than that, I just did it to keep current as per squadron policy, and not much for updating the INS.


For the OP: At night you could ignoring corrections determine your latitude with a standard sextant on the ground. In the air, since the horizon is problematic you would need a bubble sextant to be anywhere close. This latitude line (line of position with an azimuth of 360) would give you an excellent course line for east west hdgs and an excellent speed line for north south courses. In between well... just one LOP.

As far as heading goes, the azimuth of polaris is not exactly 360 all the time, but with astronomical tables and a corrections, you can get an excellent true heading check with polaris. Even without correction it would not be off more than 1 or 2 degrees.

Without a sextant and training??? fugetaboutit

Did you go to Mather? They had a cool IMAX-style planetarium there for teaching the solar system.

 

[beasly]

.....


UNT in 1993 10 miles +- from INS position and that was generous. A three star fix done properly were often with three miles or dead on......

........

I have the biggest smile on my face reading that.





Alright, gotta buy star charts and a sextant and a chrono-something...


this is gonna be a blast!

 

[granlistillo]

Did you go to Mather? They had a cool IMAX-style planetarium there for teaching the solar system.

Just missed Mather, was the 2nd class at Randolph. We missed the planetarium They had a monkey bar setup outside with sextant ports where we practiced shots at zero knots and no turbulence.

 

[beasly]

Barnes and Noble store in O-town has 1 book--Chapman' s or something and browsing through it, it reads like a Jepp Private Syllabus.


So, go to Amazon and

I am very pleased that my first Celestial Navigation book will be by my favorite conservative.

Please no snark. I make no pretense about my conservative views and get along quite well with my fellow navigators from the other side of the aisle.


Payday is Friday, so I will keep you updated. This looks like a pretty good first-step.




edit: ok, it is JC---bring on the snark!

 

[beasly]

I have Bowditch's "American Pratical Navigator" in the Amazon Cart as well.

Check out this first comment from Amazon. The paragraph in bold is mine:

If you intend to navigate upon the ocean, out of sight of land, using only celestial bodies as your "lighthouses," there are three absolute necessities: a sextant (or other means of getting the exact altitude of the sighted body); a nautical almanac or ephemeris, preferably the current issue (or a considerable ability with spherical trigonometry and an encyclopedic knowledge of the movement of celestial bodies--particularly the one you are using); and an accurate timepiece set to, or correctible to, Greenwich meridian time (Coordinated Universal Time).
Given those things, and some paper and a pencil--and ideally, a chart and a few simple instruments, like a pair of dividers or compasses, a straightedge and perhaps a set of parallel rules or a pair of triangles, you should do very well--provided that you also know how to use all of the above.
With American Practical Navigator, you can find the knowledge you need to use the above tools. It's all in there.
It is one of the textbooks used by the United States Naval Academy to teach celestial navigation, as well as the United States Power Squadrons. I am a full certificate member of the latter.
American Practical Navigator is not an essential book. There are other texts that are useful in learning celestial navigation; but, it is by far the best.



Nathaniel Bowditch, the original author of the American Practical Navigator, was born in 1773, in Salem, Mass. He sailed as a ship's master, and worked as a cooper and ship's chandler, but his all-consuming interest was in mathematics. He learned French, Spanish, German, Latin and Greek in order to absorb the discoveries of others, and at the age of 16 was reading Newton's 'Principia,' translating it from Latin--and he found errors. He later published his own findings, and they were accepted. He wrote his first almanac at the age of 15. He developed an new, simplified method of determining lunar distance, and on his voyages began to find errors in John Moore's 'The Practical Navigator,' the leading navigational text. The rest, as they say, is history.





The current American Practical Navigator, Nav Pub. No. 9, published by the Defense Mapping Agency Hydrographic Center, is in two volumes.
Any serious student of celestial navigation will want a copy.
Another volume, similarly useful, and a good adjunct to your library, will be 'Dutton's Navigation & Piloting.'
With these two volumes, and the current Nautical Almanac and your instruments, the world's seas become your thoroughfare.
Joseph Pierre, N

 

[granlistillo]

Beasly,
Think it is great you are getting into cel nav. Doing it on a boat with a simple correction for height above the water for the horizon and the ability to take quick nearly instantaneous shots while making steerage or anchored is way different than doing it in a plane. I could get into the nerdy nav speak but it puts me to sleep even thinking about it. And I think it bores everyone here at JC. I will say it is one of the most challenging things I ve done in aviation.

There was a guy trying to do a nav part 141 school with beech 18s to get the nav certificate which is still on the books. The PTS for the certificate were about what it took to get through military Nav school, and that was a 6 month syllabus, after primary nav training. Not easy task. I wish they had a military competency test for it, but it really is obsolete. Only thing it helps is on a resume and can be logged as FAR 1.1 Flightcrew member time.

My point is, that cel is cool as heck but without proper equipment for the aviation application, it wont be something you could apply in the air. Good luck though. Someday when I can buy a boat, I will take cel nav up again, but will have to do it the way it is on a boat.

 

[Autothrust Blue]

A while back I did some work for an SR22 outfit and I am amazed at how much they have put in that machine. But one thing I frequently saw was a huge reliance on the boxes for EVERYTHING. We were north of our field on a blue sky day and after maneuvers I said let's RTB. The guy began programming the GarminS. I knew what he was doing but asked if he ever used the big situation indication... called a WINDOW. He looked at me blankly.

The 'V' in "VFR" stands for virtual, right? :insane:

I see this a lot in friends who have only flown glass airplanes. I enjoy turning stuff off or ignoring the screen and just flying - some, however, become s and elbows without aforementioned big video game. I worry, because the magic is only as good as the operator.

 

[LoadMasterC141]

I did a few Space-A travels in a KC-135 when I was kid in the 80s and remember seeing the Nav using the Sextant at night. One even explained some of it to me. Pretty complex for a 10 year old unfortunately.