Home › Forums › General Discussion › Air Navigation
August 5, 2021 at 6:59 pm #10454
I was wondering if anyone else here was attempting to do celestial navigation for air navigation? I’d love to have someone to bounce ideas off of.August 7, 2021 at 5:07 pm #10456
I understand the basic procedures while using celestial navigation at sea with a sextant. But, I have no idea about the basic practices and procedures of celestial navigation when using a bubble-octant while airborne over an ocean in the 1930s & ’40s. For example: On a ship the sextant is used at dawn and dusk to obtain a site while the natural horizon and celestial object are visible a the same time… does this mean that a bubble-octant site can be made all night long??? Also, I’ve read that the bubble-octant was the worst option for attempting celestial sites while navigating on the land before GPS was invented. If this in true… why? I know that the bubble-octant was limited in usefulness… but how limited was it really??? How was it done on a daily basis? The vintage user manuals aren’t clear about the very basic principles and practices of aeronautical bubble-octant navigating.August 9, 2021 at 5:08 pm #10468
I think the biggest problem with a bubble octant on land is going to be two main effects. I don’t know how severe they are. First, It isn’t as good as an artificial horizon device, which is much more precise because it’s just reflections. Second, any massive objects that are near you will actually shift gravitational down away from the center of the earth, resulting in inaccuracies near mountains, etc. The second may seem like a minor thing, but I have read that it was enough that careful surveys of mountains and the gravitational force were required for accurate land artillery use.
However, if I can get good enough at taking shots to get accurate enough to get within about ten miles while on the ground, I figure I’ll be ready to start trying in the air and seeing how it goes.August 10, 2021 at 3:20 pm #10470
Sorry, I don’t understand your comments. We’re talking about the bubble-octant of the 1930s ’40s… are you saying this is NOT an artificial horizon device???? I certainly thought it was! Also, your discussion about the effects of gravity seem to apply to a magnetic compass and not any form of a sextant–unless I am very mistaken.August 12, 2021 at 8:17 pm #10471
It isn’t an artificial horizon the way a reflective, liquid surface is. Those are quite accurate. As for gravity, it can have a small effect on any tool or device that tries to measure ‘down’, it isn’t much, but when you’re talking about extremely precise things, the effect is there. That said, I got an A-12 a few days ago and have found what I think is the culprit behind “… the bubble-octant was the worst option for attempting celestial sites while navigating on the land before GPS was invented.”
The bubble is dancing about like mad and it isn’t small, making extreme accuracy difficult. I’m going to need a lot of practice on the ground before getting in a plane with this thing!
As far as being innacurate though, it looks like most of the inaccuracies come down to using the thing correctly. I did find this: https://journals.lib.unb.ca/index.php/ihr/article/download/27852/1882520608/1882520854
Sights can be taken at any time, and even through a hazy or cloudy sky without a horizon, which is a nice advantage! All you need to be able to see is the object you’re shooting.August 13, 2021 at 12:46 am #10472
I find this subject interesting… likewise to your Email reply to my previous questions. I am going to research your Email (below) and follow the links you’ve provided one-by-one.
I became interested in celestial navigation because of the many Amelia Earhart books that I was reading awhile back. I was going to attempt using one of the surplus bubble-octants that are for sale on the Internet. Ultimately, I didn’t go for it; and so, I am pulling for you in your practicing on the A-12. Maybe I can help you in your research? For example, have you ever seen the Web-pages of Gary LaPook? Mr. LaPook seems to be very knowledgeable about aerial celestial navigation and has done actual celnav while in flight a number of times. What made me think of Gary LaPook was when you wrote about the “dancing bubble” using a bubble-octant. In one of LaPooks many posts he describes the difficulty of getting a accurate sight with the ‘bubble’ constantly in motion from the engine vibration. His answer is to take ten sights on each celestial body, using a bubble-Octant with an “averager” attachment. He uses the number ten because of the simplicity of completing the math. I think he wrote that he can perform ten sights and do the chart work in two minutes with the averager and in three minutes without the averager attachment. 4 times 2 = equals 8 minutes [plus change] for getting readings on 4 celestial bodies? or 4 times 3 = 12 minutes without the averager?
LaPook is also the resident celnav expert for the Stratus Project:
I’ll send a reply to your Email in a few days. Have a Nice Day & Good Luck,
–JosephAugust 13, 2021 at 9:06 pm #10473
Thank you for this information about Mr. LaPook, he seams to have quite a bit of information I can hopefully learn from!
I finally pulled the trigger on the A-12 at Celestaire because of the “averaging” tool it includes (you can take an odd number of sights, measured on a bakelite drum with graphite, and from the centerpoint of those sights you can determine the median of the sights with relative ease). A more advanced averager might be nice, but this one has a nice level of simplicity to it. It remains imperfect, but with this type of navigation, the same accuracy of GPS is of course not the goal.
Thank you for the encouragement!August 13, 2021 at 11:50 pm #10474
That ‘Fredienonoon Web-page’ I sent will keep you busy for a long time to come. There is a ton and a half of information on it (I’ve been through all of it). In what year was your A-12 manufactured? Is it a ‘Link’ model? If you have the time would you look up the “Navigation to Dakar” link on the Fredienoonan site. Gary LaPook seems extremely critical of Noonan’s navigation in this article. True, they missed Dakar by quite a lot, however, Lapook proves that they changed their distination in mid-flight from Dakar to Port St Louis (I assume because of poor weather over Dakar) I couldn’t understand what Gary LaPook was trying to get at in this article.It seems like there was something more that just bad weather at play in his criticisms. If you get a chance to look the article, let me know what you think. I’ve included another web-site you might find useful below (if you haven’t seen it already:
.landfallnavigation.comAugust 14, 2021 at 12:27 am #10475
Oh, by-the-way, before I forget again: I did read and save the article you sent, “SURFACE NAVIGATION WITH THE BUBBLE OCTANT”. Great article! I loved it. I’ve saved a copy to my navigation files.
Thanks Again and See earlier post,
JosephAugust 14, 2021 at 7:46 pm #10476
Yes, it’s a link model, manufactured in 1943, per the serial. I need to adjust the index mirror (it was set up with the vernier wrong, but that should be fixable with some careful adjustment at home) but it’s worked well for a solar fix once I was accounting for the setup error.
I’ll have to read about LaPook’s opinion of Noonan. I confess that I’m younger (only 34), so the Earhart disappearance doesn’t hold quite the same “appeal” to me as a mystery, though it was a tragedy of course!August 15, 2021 at 5:12 pm #10477
The disappearance of Amelia Earhart & her navigator over the Central Pacific in 1937 is the greatest mystery and biggest conundrum of the century, which is most ironic… because it was neither a ‘mystery’ or a ‘conundrum’ as you wrote in your Email. The World Flight of 1937, which Amelia Earhart herself referred to as a “Stunt-flight’, was a screwed up, strictly amateur operation. With the exception of Fred Noonan, the navigator, who was a top professional (so he has no excuse–he should’ve known better). Even the Navy and Coastguard personal involved acted very unprofessionally–even shamefully. Her last ‘Stunt-Flight’ was poorly planned and poorly executed–it was a dangerous flight made foolhardy by unpreparedness and it was no surprise that it ended in a disaster at sea, thousands of miles from civilization. Amelia Earhart had limited skills, and way too much courage. The moral of her story? We shouldn’t start believing in are own press-clippings.
It’s good you can do your own work on a vintage bubble-octant. You can have it done by specialized service providers, but I am sure the cost would be pretty high… and the quality of their work? Who knows. Gary LaPook has some short videos of him using a bubble-octant in flight to get sun L.O.P’s… while piloting the plane!
I’ve included a hyper-link to a navigational airplane rescue article from the Web-site of Sierra Aeronautics:
https://sierrahotel.net/blogs/news/cessna-188-pacific-rescueAugust 15, 2021 at 9:46 pm #10478
> it was a dangerous flight made foolhardy by unpreparedness and it was no surprise that it ended in a disaster at sea, thousands of miles from civilization
As the saying goes “There are old pilots and bold pilots, but no old, bold pilots.”
> It’s good you can do your own work on a vintage bubble-octant.
Unfortunately, as I cracked into the manual and tried to figure it out, I rapidly realized I was totally in over my head. We’ll see how that goes.
Have a good one.August 17, 2021 at 3:44 pm #10479
The ‘Bold vs. Old’ pilots saying is cool.
I was hoping that you were the very handy type that could work on these sorts of vintage devices.
I happen to have 12 pages of a Pioneer Brand owner’s manual, January 10 1943, that I got off the Internet some time back. You’ve inspired me to read through it again. I can see why you would have trouble working on one of these! It was amusing to see the the Pioneer manual is officially marked “RESTRICTED” ha,ha,LOL,LOL– yeah the enemy might learn how to use various sextants in 1943!
This time I’ve attached a link to a nifty historic Morse Code decoder and instruction site for you below:
https://morsedecoder.com/August 17, 2021 at 10:23 pm #10480
I’m somewhat handy, but not like this kind of precision. As an avionics technician I met once said “Using a thing and maintaining it are totally different sports.”
As far as Morse goes, I’ve had some practice in it as a radio ham, but I’ve never had the speed that some of the older Elmer’s have. Just enough to be able to listen to the VOR and ILS beacons while flying and be able to tell if the letters are the correct identification without having to lookup the codes by hand.
I’ve been working on learning it quicker and more reliably using the Koch method, but that’s been taking a backseat to other things lately. You’ve reminded me I need to work on that too!August 19, 2021 at 4:07 pm #10482
Well, if either Earhart or Noonan would’ve had your workman’s attitude when it comes to learning wireless telegraphy and radio skills in general (in their case, throw in radio direction-finding as well) they may have been able to overshot or undershot the lousy airstrip on Howland Island and possibly die in full view of the Naval crew stationed there. Or, they could’ve fell victim to the wind-shear caused by the trade winds that crossed over Howland and crashed on or off the Island (the long-axis of the island was facing in the wrong direction for an airfield). Or, they could’ve survived the landing, and then on the following day, when they attempted to take-off at the same time as the thousands of alarmed sea-birds roosting on the island attempted their take-off too. Or if they made it into the air, despite their heavily overloaded Lockheed Electra from a short runway, they could possibly have flown into a dangerous storm moving in from the East (crashing the plane… or getting them lost all over again for a second time) Had they made it all the way back to the states, I have no doubt that A.E. would’ve retired permanently from her “stunt flying” endurance runs, made action movies in Hollywood instead and lived happily ever after. Fred Noonan would’ve likely have left as big a legacy as Captain JVH Ween’s doses in the history of early aerial celestial navigation
I understand the Kock method as being similar to the standardized technique employed in the training of typists. i.e. repeatedly typing letters to instill the ‘feel’ of the letters to the student. Then introducing words made up with those letters and so on, until the student is ‘touch typing’ with increasing speed and accuracy. I’ve heard it said that a good telegraph operator immediately hears sentences, rather than letters or individual words. Telegraphy has the reputation of being extremely difficult to learn. Computer programs make it easier but it’s still difficult. Charles Lindbergh’s wife, Ann Morrow Lindbergh, obtained her license in telegraphy in order to accompany her world-famous husband on his flights. She complained about how difficult it was to become proficient in it. Ann was also proficient in applied radio communicating; and so, she was the perfect role-model that Earhart should have made the serious effort to emulate.
The VOR/ILS beacons you referred to are updated versions of earlier LORAN beacons?
Astronomical coordinate Systems
You must be logged in to reply to this topic.