Celestial navigation and Machado's five questions

[beasly]

Rod Machado has a fantastic "self talk" thing for IFR:

• Where am I?
• Where am I going?
• How do I get there?
• What comes next?
• What comes after that?

Now, Rod, is in an aircraft, with navigation equipment so the answers to the question are .....drumroll....in the aircraft.

But, what if you are alone, at night , somewhere on the Earth with no compass, no charts.

Looking at the stars, can we answer Machado's quintent?

What can we determine?

• Cardinale points?
• Position?
• ???

The impetus for this discussion is the VOR.

With my IFR students I put them through exercises using a VOR/VOR receiver , a compass and a chart. With those 3 tools, you can determine position and heading. Meaning that, in the plane, under the hood in seconds they could point to me on the chart where their a.c was and which way it was flying. (yes, distance via dme or cross radials.is available,...bear with me)

Subtract the compass, and you can still do quite a bit of navigation using just a VOR/VOR receiver pair. Specifically: what hemisphere of the VOR "circle" am I on and what radial am I on (and direction with the "arrows in flux" but that is deep voodoo).

Its an amazing tool once you know how to use it.

So, drop your butt somewhere on God's good Earth and you need to navigate to the local watering hole, look up and given your eyes, a clear night and the stars, how many of Machado's 5 can we answer?

• Where are you?
• Where are you going?
• How do you get there?
• What comes next?
• What comes After that?

Fwiw, I am 48 years old, and I cannot point out the North Star.


Let's take it from there.

 

[Boris Badenov]

I'm confused. Are you asking whether we know that you can triangulate your position from two VORs? That can't be what you're asking. So we're flying along with a chart, two VOR receivers, and no compass. Do we know what VOR we're tuned to? Is there just one? Do we know where it is/they are? As far as celestial navigation goes, I forgot my sextant.

 

[beasly]

I'm confused. Are you asking whether we know that you can triangulate your position from two VORs? That can't be what you're asking. So we're flying along with a chart, two VOR receivers, and no compass. Do we know what VOR we're tuned to? Is there just one? Do we know where it is/they are? As far as celestial navigation goes, I forgot my sextant.

Sorry for the confusion.


The VOR example is a great way to simplify the principles.

The purpose of the post, is to simplify it further: No VOR's no Compasses (no airplane either)

The only equipment is the stars.

What of Machado's five can we answer?


Can we answer even the first two: Where am I? Where am I going?


I don't know.


hence this post.

Cheers.

 

[drunkenbeagle]

You can answer all of those questions with the stars, but you need a sextant, and as important, an accurate clock. This is actually what the USAF did up until the late 50's. (can't assume naiads will work over Russia)

You can even deduce your heading and ground speed with accurate charts, old school sailors are familiar with this.

 

[beasly]

You can answer all of those questions with the stars, but you need a sextant, and as important, an accurate clock. This is actually what the USAF did up until the late 50's. (can't assume naiads will work over Russia)

You can even deduce your heading and ground speed with accurate charts, old school sailors are familiar with this.

S


Awesome.

How?

How does it break down?


To use a VOR anology (no charts) ...first you tune the VOR , then you center the dial. With that, you can say, where am I in relation to that VOR.


Can you do Celestial navigation using ONLY the stars? If not, what are the minimums.


It really helps to reduce things to the simplest case.

Maybe Machodo's questions are not the correct ones to ask; if not, sitting on a random place on the Earth's surface, looking up at the sky, what navigational questions can I answer?

• What are the Cardinal points?

If I am dropped anywhere on Earth and I can see the night sky, can I answer that question?

 

[Boris Badenov]

You would need tables of the declination of the various celestial bodies, a sextant, a chart, and a working knowledge of trigonometry, but yes, you could determine your position.

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

Things obviously get a bit trickier if you're in motion when making the various observations necessary. I hasten to add that I know nothing more than the very general theory behind how it's done, but in essence, it's a three dimensional version of triangulation.

http://en.wikipedia.org/wiki/Celestial_navigation

 

[beasly]

You would need tables of the declination of the various celestial bodies, a sextant, a chart, and a working knowledge of trigonometry, but yes, you could determine your position.

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

Things obviously get a bit trickier if you're in motion when making the various observations necessary. I hasten to add that I know nothing more than the very general theory behind how it's done, but in essence, it's a three dimensional version of triangulation.

http://en.wikipedia.org/wiki/Celestial_navigation

Thanks, that looks like fun.

 

[Orange Anchor]

You can answer all of those questions with the stars, but you need a sextant, and as important, an accurate clock. This is actually what the USAF did up until the late 50's. (can't assume naiads will work over Russia)

You can even deduce your heading and ground speed with accurate charts, old school sailors are familiar with this.

Actually much later than that. We routinely flew long celestial legs with the boom taking shots and the nav plotting as late as my departure from the USAF in the 70s.

 

[CoffeeIcePapers]

Sailors have done this for 100's, if not 1000's of years. For the JAA ATPL, you need to take a class and exam on celestial navigation. I can't think of any scenario where I wouldn't have a working compass, however.

 

[drunkenbeagle]

Sailors have done this for 100's, if not 1000's of years.

Well, actually just the last 150 years or so. Before that, we did not have accurate enough clocks. The ship's chronograph made it possible to determine longitude.

Before that, ships would often just stay on the same line of latitude, even if it made the trip longer.

 

[Autothrust Blue]

Grandpa Blue did exactly what has been described here on the Pan American flying boats, crossing oceans, and consistently finding land (and the right bits of land) every time.

I'd like to learn how to do all this, out of curiosity. The airplanes I fly would have to get pretty far down, though, before it becomes "all you've got". A basic knowledge would be nice to have (yet another) method to do gross checks for accuracy, though.

For the JAA ATPL, you need to take a class and exam on celestial navigation. I can't think of any scenario where I wouldn't have a working compass, however.

Really really handy and applicable today, huh...the A340-600 definitely has an astrodome where you can stand with a sextant.

 

[ppragman]

Well, actually just the last 150 years or so. Before that, we did not have accurate enough clocks. The ship's chronograph made it possible to determine longitude.

Before that, ships would often just stay on the same line of latitude, even if it made the trip longer.

Check out the Astrolabe, or Polynesian Way Finding, I think there might be a longer history than just that.

 

[granlistillo]

For the JAA ATPL, you need to take a class and exam on celestial navigation. I can't think of any scenario where I wouldn't have a working compass, however.

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.

Actually much later than that. We routinely flew long celestial legs with the boom taking shots and the nav plotting as late as my departure from the USAF in the 70s.

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

 

[granlistillo]

Really really handy and applicable today, huh...the A340-600 definitely has an astrodome where you can stand with a sextant.

I met a flight engineer that told me they had a sextant on a 707 FWIW. Of course the astrodome of the 30s and 40s was replaced by periscopic sextants by the 50s. Even had star tracker for space flight and I think the B-52??. INS was the first nail in the coffin for celnav and GPS hammered it shut. The one great thing about cel nav is it can't be jammed (apart from clouds) or meaconed.

 

[RICHARD5]

Sailors have done this for 100's, if not 1000's of years. For the JAA ATPL, you need to take a class and exam on celestial navigation. I can't think of any scenario where I wouldn't have a working compass, however.

Without an accurate chronometer you could find your lat but not your long. Accuracy of a time piece had long been the fly in the works for navigators. It was only relatively recently the problem was resolved.

However, Polynesians had been able to accurately sail from island to island. (Island groups yes, but also specific islands.) They did this with knowledge of only a few stars but mostly by knowing the seasonal weather patterns and subsequent wave patterns.

Hawaii is thought to have been settled around 800 AD. Arcturus was the star of choice leading to the latitude of Hawaii.

BTW: Find Polaris (North star) and one can find just about every constellation and star for navigation purposes. And the handle of Ursa Major points to Arcturus and Spica, two stars heavily used in navigation. The saying is, "Arc to Arcturus, speed on to Spica."

Navigation, including celestial, is very interesting and useful. But I've been sailing all my life so I guess it's natural. Don't be afraid to learn celestial nav.

 

[beasly]

Wow!

JC is great.

There are actually other human beings on this planet who wonder about this stuff.

Freaking awesome.

:clap:


Anybody have any elementary scenarios that we can understand and learn from?

Things like, "if feels like summer and the sun is way "x", therefore I am in the Northern Hemisphere"

or: "I am on the North Pole because..."

or. "I am on the South Pole because..."


or: "that way is East because it is night and..."
or: "That way is East because it is day and..."



things like that.

An analogy with the VOR indicator, is I can tell what "hemisphere" in relation to the VOR I am just by looking at the To/From indicator.

For example, if the indicator looks like this:

I immediately know that there is no way in hell I am North of the station. I am somewhere in the "vor hemisphere" between W and E.

Can we do even that by looking at the sky?

 

[beasly]

Without an accurate chronometer you could find your lat but not your long. Accuracy of a time piece had long been the fly in the works for navigators. It was only relatively recently the problem was resolved.

However, Polynesians had been able to accurately sail from island to island. (Island groups yes, but also specific islands.) They did this with knowledge of only a few stars but mostly by knowing the seasonal weather patterns and subsequent wave patterns.

Hawaii is thought to have been settled around 800 AD. Arcturus was the star of choice leading to the latitude of Hawaii.

BTW: Find Polaris (North star) and one can find just about every constellation and star for navigation purposes. And the handle of Ursa Major points to Arcturus and Spica, two stars heavily used in navigation. The saying is, "Arc to Arcturus, speed on to Spica."

Navigation, including celestial, is very interesting and useful. But I've been sailing all my life so I guess it's natural. Don't be afraid to learn celestial nav.

Awesome post, thx.

BTW: Find Polaris (North star) and one can find just about every constellation and star for navigation purposes. And the handle of Ursa Major points to Arcturus and Spica, two stars heavily used in navigation. The saying is, "Arc to Arcturus, speed on to Spica."

​

That is how a pilot thinks. "where the heck is Polaris? there it is! ok, that means the handle of Ursa Major is there! yep, I see it. ..."
agian, thx.


Rambling thoughts below....



Are all those stars available anywhere on Earth? I have a nagging thought that the Northern Hemisphere folks use "their stars" and the Southern hemisphere folks "their stars"

If every star in the sky is available to anybody sometime, that is an important concept. so is the converse.

The converse is very interesting too. lets take the extremes to set some boundary conditions.

If I am on the North Pole, then I assume I see stars that somebody on the South Pole will never see;

If this is true, then we have taken a first step in understanding celestial navigation. Theoretically, just before I freeze to death, I will have the satisfaction of knowing what pole I am dying on!

Ok, what are those stars?


Lets take another point about this situation: the climate cues. On this boundary condition it is cold, so the climate cannot influence our inference. Another thing I have read but not experienced is that you only get "so much daylight" on the poles during different seasons.

This raises some questions. Is the duration of light and dark different depending on the pole you are on?


fun stuff.



.

 

[RICHARD5]

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

I suggest familiarizing yourself with a sky chart. Don't download it from the 'net, go to a bookstore and get the real thing. Find the major and minor stars, see how the various planets pass through the sky, find local SR and SS. Begin to see relationships of various stars and constellations and how they change through the night and through the seasons. Pretty soon your eyes will be zooming across the night sky as you make your way from star to star. Naturally, you'll begin to see how specific stars can be used to reference your position. It's a practical and worthwhile pursuit.

I still think a copy of Bowditch's Practical Navigator is a useful reference for the aviator as well as the mariner.

 

[RICHARD5]

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.

 

[beasly]

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

I suggest familiarizing yourself with a sky chart. Don't download it from the 'net, go to a bookstore and get the real thing. Find the major and minor stars, see how the various planets pass through the sky, find local SR and SS. Begin to see relationships of various stars and constellations and how they change through the night and through the seasons. Pretty soon your eyes will be zooming across the night sky as you make your way from star to star. Naturally, you'll begin to see how specific stars can be used to reference your position. It's a practical and worthwhile pursuit.

I still think a copy of Bowditch's Practical Navigator is a useful reference for the aviator as well as the mariner.

Richard5

Thank you.

I Googled Celestial Nav at work today and Bowditch's work was obviously treated with reverence. I forget the specifics, but one of the pages in his work was specifically designed as a "tear sheet" that you would use as a bookmark as you progressed on your navigation. (I will have to re-read that--anyway it was/is a working tool)

What is a good sky chart?

How big? how much? for what place?


thx in advance.

b