Celestial navigation

[Guest DC3 Pilot]

Is it possible to use celestial navigation (day and night) with FS9 and the M.A.A.M. DC-3 cargo plane (which has no navigation bubble)? I'd be willing to go outside (spot plane) to shoot the sun or key stars, giving up a tad of realism :-). I guess the question is really whether the location of the sun and the major stars normally used for celestial navigation are properly modeled in FS9, and, if so, whether you can do this with real instruments or would be required to have virtual capability. Also, any pointers (web sites, forum posts, etc.) that would provide useful information for celestial navigation in FS9 would be appreciated. A couple of my "round the world" trips involve extensive over-the-water segments :-). Thanks.

[Dark Moment 0]

Here you go. And what's more, if you'd like radio range equipment and a driftmeter, I can tell you where to get that too! At Avsim.com .....FS2004 Simulated Aircraft Bubble Sextant As travel by air developed and matured, navigation over long distances also developed and improved. In the early days, however, air navigation essentially used ship navigation techniques adapted for aircraft. Without "landmarks", the navigators used Ded Reckoning (DR) and the stars. Celestial or Astronomical Navigation provides a means of obtaining Lines of Position (LOPs) from the stars. Crossing LOPs will fix a position. It requires a chart, and a planned course on that chart, with waypoints specified by Latitude and Longitude, an assumed time of arrival at each waypoint, and stars (including the Sun, Moon, or planets) in view. In the 1940s, extensive tables of star positions were made available to air navigators to be used with sextants to obtain these LOPs. In the tables, all times involved are GMT. This data is available from the Internet in "ready to use" form. This gauge simulates the sextant, and the process by which one obtains a LOP, or crossing LOPs to obtain a position, or fix. Can be used with any FS2004 aircraft. Includes comprehensive browser-based manual and references. Filename: dc3_bbsx.zip License: Freeware Added: 6th December 2004 Author: Dave Bitzer, Mark Beaumont Size: 991kb Mark "Dark Moment" BeaumontVP Fleet, DC-3 AirwaysTeam Member, MAAM-SIM[a href=http://www.swiremariners.com/cathayhk.html" target="_blank]http://www.paxship.com/maamlogo2.jpg[/a]

[Guest DC3 Pilot]

Great, thanks Mark! The perfect answer :-)

[Guest DC3 Pilot]

Hi,Anyone know where I can pick up an inexpensive, plastic bubble sextant to practice "backyard" celestial navigation? My object is to gain a bit of experience identifying navagiational stars and using the sextant in order to add realism to my use of the Bitzer-Beaumont bubble sextant program in my M.A.A.M.-SIM DC-3. Many thanks,Gary

[Dark Moment 0]

No, but if you keep your eyes open you may find a real Mk. IX on Ebay in due course! They come up now and again and are not necessarily expensive. That may depend on whether they still work or not, of course!MarkMark "Dark Moment" BeaumontVP Fleet, DC-3 AirwaysTeam Member, MAAM-SIM[a href=http://www.swiremariners.com/cathayhk.html" target="_blank]http://www.paxship.com/maamlogo2.jpg[/a]

[Guest SPOFF]

HI GARY: I think the term used with reference to Marks Bubble Sextant is "Simulated". I havn't tried this simulated sextant yet but I have difficulty visualizing how this can be like the real thing as to application. (No offense intended Mark) I am familiar with (and have practiced) Marine Celestial Navigation and it is not quite as simple as one might hope. You have to "identify" the star you are going to use for your shot...Generating the first LOP. You need at least TWO shots (LOPs) to get a FIX...ie.. a second star.. There are calculations to perform, using two different published "Tables". For Air Navigation, I believe one is HO-249. The other is the "Air Almanac". How you can do this in the simulator I would be willing to consider but can't at present visualise how it would work. I tried to download the simulated sextant yesterday and: "Page Not Available".The only essential difference between a Marine Sextant and an Avaition Bubble Sextant is the "Bubble" ..which gives you an artificial "HORIZON", which makes it possable to measure the angle between the star and the "Horizon"..at an instant in time... which you must record at the time of the shot. An airplane is at some altitude ABOVE sea level and therfore one would be looking DOWN at the horizon making the measurement of the angle betweent star and the horizon incorrect.There ARE "Plastic" Marine Sextants available for "Back Yard Practice" but I know of no "Bubble" Sextants available. If you are REALLY interested, pick up the marine version and give it a try. The principle is identical. In fact you can get "Bubble" attachment for a marime sextant to use when the horizon is not available.Can't imagine this explanation will make things any clearer, but I can only hope...SPOFF

[Guest DC3 Pilot]

Hi SPOFF,I've been using the Beaumont-Bitzer simulated bubble sextant in my M.A.A.M.-SIM DC-3 and find that it is a very good approximation of the real deal (I, too, used to do a tad of marine celestial navigation, though was never an expert by any means). There are certain constraints you have to place on yourself, of course -- mainly not to select and shoot any celestial body that you can't see :-) Using the navigation dome (or simulating it by going to Spot View) allows you to check out what's available and not either below the horizon or obscured by clouds. Then, by using the U.S. Naval Observatory "Celestial Navigation Data for Assumed Position and Time" data (http://aa.usno.navy.mil/data/docs/celnavtable.html) you can simulate the "page a day" almanac used in the 30s and 40s. Plotting LOPS is all per standard celestial navigation practice.The reason I was seeking a plastic bubble sextant for "backyard" practice is the same reason they use them in airplanes -- either I can't see the horizon at all, or it is distorted by surrounding hills, foliage, etc. The bubble approach would allow me to get some real world practice to go along with my use of the simulated bubble sextant in my DC-3. Your point about a bubble attachment for a marine sextant is well taken, and thanks for that very good idea. I did see a Mark IX for sale on E-Bay, per Mark's suggestion, but it was from the U.K. and shipping was prohibitive. However, I'm going to keep looking there as well.Thanks,Gary

[Dark Moment 0]

>HI GARY: I think the term used with reference to Marks>Bubble Sextant is "Simulated". I havn't tried this simulated>sextant yet but I have difficulty visualizing how this can be>like the real thing as to application. (No offense intended>Mark) I am familiar with (and have practiced) Marine Celestial>Navigation and it is not quite as simple as one might hope.SPOFF, if you haven't tried it ....... ;)No offence taken, naturally; but I would only highlight that it is easier to write authoritavely about things when you've actually tried them, perhaps!Of course there are compromises - we're talking staring at computer screens, thus the term 'simulated' - but I think you'll be pleasantly surprised, nonetheless.MarkMark "Dark Moment" BeaumontVP Fleet, DC-3 AirwaysTeam Member, MAAM-SIM[a href=http://www.swiremariners.com/cathayhk.html" target="_blank]http://www.paxship.com/maamlogo2.jpg[/a]

[Guest SPOFF]

MARK,GARY: I'm Flabergasted! I had NO IDEA that Flight Simulator modeled the stars and planets in their correct positions and brightness, let alone for any date you can think of in the Simulated sky. I thought the stars in FS9 were just random specs put there for effect. It's been 25 years since I worked a sight reduction and then only using the sun. Truth be known, I never bothered to learn star identification. On a boat sailing at 5 or 6 knots, one only had to take three or four shots..average them, and then wait a couple of hours and do it again. After the second round, "advance" the first LOP on the plotting sheet by that amount..course and speed, etc. Waiting gave the sun a chance to move to a new position for the next LOP. In an airplane at 200 knots this might not be as acceptable.Obviously, if using the stars, you don't have to wait two hours to find out your position because you use more than one star, one after the other. MUCH food for thought. I think I need to go back and drag out all my celestial work sheets and do some REVIEW. I still have my old Cassens and Plath Sextant. SPOFF

[Guest kennethg]

Try West Marine on-line or any boat supplier, there are plastic sextants made by Davis Instruments that work pretty well for about $45. I wouldn't bother with anything on Ebay that's advertised as a "brass sextant" since those are usually cheap trinkets designed to look like a sextant, but not operate like one. I just finished a celestrial nav course through the US Power Squadron and found it a facinating course. The only problem with a regular sextant is you need a "real" horizon for them to work, which is the surface of the ocean. In fact, one of the steps you need to do to use it, is to figure out how far above sea level you are, even 6 feet makes a significant differnce. That's why they made bubble sextants: the bubble supplies the horizon that a plane is too high to see correctly.

[Guest DC3 Pilot]

Mark,What is the source of the data for the magnetic variation readout on the bubble sextant?Thanks,Gary

[Guest SPOFF]

HI MARK: Sorry to belabor this point but I'm STILL a little confused. My exclamation/question.. ??? in a previous post that Celestial Navigation WAS possable in FS9 seems to have gone unanswered. QUESTION RESTATED: ARE the stars "modeled correctly" in FS9 suitable for REAL Celestial Navigation??? Best regards; SPOFF

[Dark Moment 0]

Unanswered? Sorry if I was unclear. I posted the spec of the simulated sextant in the second post in this thread, before you joined .. maybe you missed that, SPOFF? And have you still not tried the FS9 sextant to find out for yourself?Yes, the stars are modelled correctly in FS9 for real celestial navigation. There are add-on enhancements that add some stars and constellations that are missing in the default, but even the default is pretty impressive. Our multiplayer group at DCA were admiring the Southern Cross in Uruguay only last night.MarkMark "Dark Moment" BeaumontVP Fleet, DC-3 AirwaysTeam Member, MAAM-SIM[a href=http://www.swiremariners.com/cathayhk.html" target="_blank]http://www.paxship.com/maamlogo2.jpg[/a]

[Guest SPOFF]

MARK: I was hoping you would say that Celestial in FS9 "wasn't really" REAL. Now I'm going to have to drag out a bunch of 25 year old celestial worksheets and remember it all over again. I don't really have a reason for using the sextant while flying but I DO HAVE a Big curiosity about how things work. ("Curiosity killed the cat")I downloaded the Sextant but there may be a problem for ME. You already know how "Expert" I am when it comes to computers..altering files..renaming files..yada yada. Remember my Reading scenery? I've got the sextant install instructions on my desk. MAYBE, If I really feel Lucky.... :-cool Regards: SPOFFEdit: Sp

[Dark Moment 0]

>Now I'm going to have to drag out a>bunch of 25 year old celestial worksheets and remember it all>over again. Naahhh ... just follow our README. Otherwise you WILL get confused :)MarkMark "Dark Moment" BeaumontVP Fleet, DC-3 AirwaysTeam Member, MAAM-SIM[a href=http://www.swiremariners.com/cathayhk.html" target="_blank]http://www.paxship.com/maamlogo2.jpg[/a]