US Navy’s new unhackable GPS alternative.

[NutLoose]

https://www.popularmechanics.com/military/research/a36078957/celestial-navigation/


The Navy’s Automated Celestial Navigation System would replace manual shipboard measurements with something more accurate, while Special Operations Command experts are developing a handheld device for commandos. Both pieces of tech are aiming for GPS-level precision.

“The best accuracy for celestial navigation with certainty is within a couple of meters,” says Benjamin Lane of the Advanced Position, Navigation & Timing Instrumentation unit at Draper Laboratory in Cambridge, Massachusetts. “In practice, we are within a factor of a few of that.”
SPOOFING, HACKING, OR DESTROYING THE STARS? NOT HAPPENING.
The new systems use infrared rather than visible light for locating stars, allowing daytime navigation. The stars shine just as brightly in the day sky as they do at night, but their light is masked by sunlight scattered by the atmosphere. The scattering is strongest at short wavelengths. If you’ve ever glimpsed the sky, you know that blue light is scattered the most. But glimpse that same sky with a filter that allows only infrared light, and the sky suddenly becomes dark—and filled with stars.

“Twenty years ago, these infrared sensors were quite expensive,” says George Kaplan, a consultant for the U.S. Naval Observatory. “Since then, costs have been going down and the pixel count is getting higher.”

The rise of celestial navigation is also helped along with another piece of tech called a “phased optical array,” which does not need to be pointed at a section of the sky like a telescope does. This type of sensor does not have a lens to focus, but instead has an array of tiny meta-material antennas to capture light. A processing unit can phase-shift the signal from each antenna to achieve the same effect as a movable, focusing lens.

[megan]

Every thing old is new again, SR-71 used a star tracker as its prime means of navigation.

[flighthappens]

Every thing old is new again, SR-71 used a star tracker as its prime means of navigation.

Depending on who you believe, 3 blokes did that a little over 2000 years ago!

[Petit-Lion]

And with several civil alternatives, the Pentagon's GPS decommissioning is in the future

[GlobalNav]

Depending on who you believe, 3 blokes did that a little over 2000 years ago!

Not with accuracy on the order of a few meters. Not even the SR-71 star-tracker.

[Asturias56]

How BIG is the device?

[Less Hair]

This is what the SR-71 had.
https://timeandnavigation.si.edu/multimedia-asset/nortronics-nas-14v2-astroinertial-navigation-system
90 Meters precision at Mach 3+ is not that bad. This device is said to have inspired the "character" R2D2 from Star Wars.

[hoss183]

Defeated by cloud though, que the enemy developing weather control.

[Less Hair]

Clouds at FL850?

[hoss183]

Clouds at FL850?
They are sailing ships at FL850 now?

[megan]

Clouds at FL850?The -71 crews have noted clouds to 70,000, U-2 pilots icing at 60,000.

[Asturias56]

This is what the SR-71 had.
https://timeandnavigation.si.edu/multimedia-asset/nortronics-nas-14v2-astroinertial-navigation-system
90 Meters precision at Mach 3+ is not that bad. This device is said to have inspired the "character" R2D2 from Star Wars.


Thanks - needs a bit of work to fit on my wrist I think........... but then the original GPS units wouldn't fit on my kitchen table

[Less Hair]

It is using stars. Celestial navigation. Data fed into the aircraft nav system. The SR-71 was meant to be used for Post-SIOP reconnaissance when no working satellite or nav-emitter would exist anymore.

[flash8]

US Army I think still use the DAGR which has anti-spoofing technology, they did a while back anyhow when I worked for them, although have not ever heard of a case of spoofing a GPS in theatre - nobody I spoke to about it seemed too worried, and many folk carried/wore a consumer Foretrex 401, which seemed to do the job at least as well (using MGRS setting, civilian satellites, and for 1/10th of the price).

[air pig]

Royal Navy still teaches the use of a sextant. The US Navy has only in recent years re-introduced teaching it.

https://www.youtube.com/watch?v=9IIMrk0QrIY

[MountainMetman]

Be nice to get a system that alos doesn't lose accuracy in the event of a major solar storm heating the ionosphere and changing the signal path for the GPS signals.

[NutLoose]

US Army I think still use the DAGR which has anti-spoofing technology, they did a while back anyhow when I worked for them, although have not ever heard of a case of spoofing a GPS in theatre - nobody I spoke to about it seemed too worried, and many folk carried/wore a consumer Foretrex 401, which seemed to do the job at least as well (using MGRS setting, civilian satellites, and for 1/10th of the price).

what about

https://www.voanews.com/silicon-valley-technology/ben-gurion-incident-exposes-wests-vulnerability-gps-disruption

https://www.defensenews.com/global/europe/2018/11/16/finland-norway-press-russia-on-suspected-gps-jamming-during-nato-drill/

[gums]

Salute!

Do not diss those folks at Draper and other places that developed and fielded nav gear that used the stars to help their inertial systems.

I worked with the Draper folks and the USN to develop ways to check on the guidance systems of the Trident missiles. Parts were hard to get because many vendors had gone outta business. Meanwhile, the subs were cruising about with all those missiles and the USN wanted to make sure their guidance systems still worked as advertised. Our company was hired to help with a test program that verified the specified accuracy of the missile's guidance system.
.
During the Reagan years, many documents about the Trident missile were put on the street. Was like us "catch us if you can" challenge. The basics were well known, but nobody else could come close to making such a system work. Lemme put this into perspective...... the sub could launch a missile from 3,000 or 4,000 miles away and it would hit inside a futbol field.

The thing that amazed me was the guidance unit had an optical component that was programmed to look for a star during mid-flight and correct the inertial system. A series of holes in the gimbal housings would line up and find the star and then correct the inertial and then.... Remember, these folks were the ones that developed and fielded the Apollo guidance units, and we know what they did.

I like the idea of using stars versus satellites. A bad guy could seriously wreck havok on the sats, but how could they move the stars? I have always wondered about depending too much on the sats. And I helped with the original JDAM mission planning efforts.

Gums sends...

[ORAC]

The U.K. has been working on a “quantum compass” (far more accurate INAS) for years.

First example is large and only suitable for boats (new Trident subs?). But compare the size of the very first INAS unit (USS Nautilus) and recent commercial INAS units.....

https://www.imperial.ac.uk/news/188973/quantum-compass-could-allow-navigation-without/

https://www.zdnet.com/article/gps-killer-quantum-compass-promises-satellite-free-navigation/



https://cimg8.ibsrv.net/gimg/pprune.org-vbulletin/440x295/image_aeb2fb803452e18939f3844507bb25f795a05282.jpeg

https://insideunmannedsystems.com/worlds-smallest-better-gps-inertial-navigation-system-now-available/


https://cimg2.ibsrv.net/gimg/pprune.org-vbulletin/800x506/image_96a2ce17c474c9a30c4593c0579e0fecc2bfc02c.jpeg

[B2N2]

Clouds at FL850?

Noctilucent clouds, I’ve seen them only once

https://weather.com/science/weather-explainers/news/2019-06-10-noctilucent-clouds-united-states-june-2019

[Asturias56]

Seen them a few times - always worth looking after dusk or before dawn if it's really clear - quite ethereal

[Audax]

IIRC, an F84 with some sort of Astro/sun/star tracker under a glass dome in the nose crossed the Atlantic decades ago.

[LowObservable]

First electro-optical astro-inertial system was developed for the Northrop SM-62 Snark, starting in the late 1940s. Airborne star acquisition and tracking was demonstrated around 1952. Snark of course was cancelled but Northrop built the Blackbird's system and that for the B-2. Kollsman developed an astro-tracker integrated into the B-58's NAS, and the Skybolt missile had one built into the pylon to update the INS immediately before launch. There is a Snark system in the Udvar-Hazy.

https://cimg9.ibsrv.net/gimg/pprune.org-vbulletin/727x900/snark_nav_b826e2bd04578f5ed7614ed5beb65a6dff23c2f6.jpg

[GlobalNav]

First electro-optical astro-inertial system was developed for the Northrop SM-62 Snark, starting in the late 1940s. Airborne star acquisition and tracking was demonstrated around 1952. Snark of course was cancelled but Northrop built the Blackbird's system and that for the B-2. Kollsman developed an astro-tracker integrated into the B-58's NAS, and the Skybolt missile had one built into the pylon to update the INS immediately before launch. There is a Snark system in the Udvar-Hazy.

https://cimg9.ibsrv.net/gimg/pprune.org-vbulletin/727x900/snark_nav_b826e2bd04578f5ed7614ed5beb65a6dff23c2f6.jpg

No doubt astrotrackers have worked successfully in different applications, but do doubt they could achieve mil GPS accuracy. A highly precise system that would require a large maintenance cost. Worthwhile for SR-71 and U-2, but I’d suppose too expensive for wider use. The C-141A Starlifter had provisions for an astrotracker, but was not installed for operational use.

Perhaps advances in inertial platforms and solid state electronics has enabled improved accuracy, reliability and maintenance costs.

[gums]

Salute!

Where have you flown recently, Global?

The inertial platforms since the late 70's have demonstrated a mile per hour drift on high performance fighters that introduce many more gees and turn rates and... than your basic 747 cruising level for 10 hours. So a good position update can really help things.

The Trident system had super inertial sensors, but the big thing was the mid course position update using a star. The clever Draper folks used that for basic position, but also to calibrate the inertial. The system did not need constant updates or signals from a GPS sat.

If the Navy or Draper says a system can find a star in broad daylight, I tend to believe them. I agree that heavy clouds and such are a biggie, so a system they are talking about should not be the most inportant nav system for ultimate mission success. One thing you can do nowadays that was not possible 50 years ago is reset your strapdown or RLG inertial at last known position, then apply corrections to the inertial sensors.

I like the idea of a system that is independent of the sats. I might also add that one platform I flew long ago used a doppler system to "help" the inertial. There may be fairly simple sensors to help a good inertial provide very accurate positional and body rates.

Gums sends...

[megan]

If the Navy or Draper says a system can find a star in broad daylight, I tend to believe themThe SR-71 proved that beyond question, though to ease alignment they used a light source in the hangar ceiling for initial alignment, helpful no doubt in the typical UK weather. :p A hot alignment took 18 minutes, cold 36 minutes, exclusive of warm up time. A scramble would of course require an inflight alignment. Catalogue had data for 61 stars, sun, moon and planets were excluded. Until the star tracker had a lock nav was by inertial.

[gums]

Salute!

Thank you, Megan.

I only know two Blackbird pilots, so I cannot confirm their astrotracking doofer.

The "newer" systems I worked with a bit over twenty years ago watered my eyes. The strapdown inertial for AMRAAM aligned in seconds and could get you within a hundred yards in one minute of manuevering flight.

I really like the idea of using something beside the GPS stuff.

Gums sends...

[JimNtexas]

The FB-111 had an astrotracker.

[Asturias56]

"The strapdown inertial for AMRAAM aligned in seconds and could get you within a hundred yards in one minute of manuevering flight."

What was the drift over a few hours GUMS?

In my experience the advantage of GPS is no drift, nor worry about being able to see the stars, constant updates

[BEagle]

Talking to a Habu who was giving a talk on the jet, I asked how good the astrotracker was at aligning at Mildenhall under cloudy skies with East Anglian low stratus off the North Sea....

"Not very!" was his answer! But once R2D2 could sniff out the stars up at FL nosebleed even at Mach lots, it was VERY good!

[gums]

Salute!

Yeah, Astur, prolly a nm per hour or less. Of course, it only had to get the missile within x yards after 30 seconds, and it was being used for a cluster bomb guidance system on a new system.

The reason I mentioned it was the technology advancements since the first large scale use of inertials and then the development of strapdown systems. The alignment times decreased by an order of magnitude. So way I see it is tonight I could lay my iPhone down next to me at the campsite and it would look at the stars and compare with my Starmap program and then compute.

I just have bad waves about a major conflict where the other side could disable or degrade the existing GPS system enough to cause big problems.

Gums sends...

[beardy]

it would look at the stars and compare with my Starmap program and then compute.
Only if it could see the stars and there are a lot of places and times where it couldn't, the sky is often Obscured By Clouds.
I agree that reliance on an active transmission is inherently a bad idea.

[ORAC]

Not sure if this all ties just into OneWeb or also the US PNT systems*……

http://bidstats.uk/tenders/2021/W13/747897237

https://www.gov.uk/guidance/space-based-pnt-programme

https://www.cityam.com/oneweb-in-talks-to-play-role-in-new-navigation-system-to-rival-gps/

* https://www.c4isrnet.com/battlefield-tech/space/2020/09/14/army-to-award-contract-for-gps-alternative-by-end-of-september/

* https://www.militaryaerospace.com/sensors/article/14183941/pnt-opensystems-architecture-alternatives-to-gps

[Asturias56]

"the alignment times decreased by an order of magnitude. ""

I remember it well - and the nagging fear that the drift on YOUR unit was one of the outliers on the curve............

Of course the old methods were'nt foolproof. I know of someone who set off to cut a 50 km path through a rain forest and dialed in the magnetic deviation on their survey gear on the "wrong" side". Only found out when they arrived, several weeks later, on a river 50+ kms away - several kms off plan...........

[Hydromet]

Of course the old methods were'nt foolproof. I know of someone who set off to cut a 50 km path through a rain forest and dialed in the magnetic deviation on their survey gear on the "wrong" side". Only found out when they arrived, several weeks later, on a river 50+ kms away - several kms off plan...........
Asturias56, this reminds me of an almost similar when I was working in PNG. We had to mark out the alignment for a straight road through thick jungle with completely opaque canopy, though not as far as yours. I was all prepared to do a proper survey, but one of the locals was insistent that we didn't need to. I decided to give him his chance, and he walked and marked a straight line, and popped out on the river exactly where we were meant to.

[Asturias56]

I've worked in West Irian and Kalimantan and that story doesn't surprise me at all - if you live in those god-forsaken forests you must develop skills us incomers have no idea of..................

[SASless]

In this month's US Naval Institute monthly magazine is an article about the need for a ground based replacement for Space based GPS navigation and Time Signalling in the event of War breaking out.

The Russian doctrine assumes all Space based systems shall be made Combat In-effective and are taking measures to provide backup systems.

Traditionally, the US Coast Guard provides navigational systems for the US DOD and ran the legacy LORAN-C system for Fifty Two Years before ending that program in 2010.

There is a proposal for the creation of a new eLORAN system to be operated by the USCG among requirements that it be deployable to combat areas when needed to replace losses of GPS coverage.

The article reports the Russians have used GPS disruption tactics in Syria and the US Military has also done similar actions at various times.

If Western Militairs, including the RAF and RN along with the US Forces were to lose all use of GPS Navigation services and its knock on uses.....are we prepared for that contingency?

Is eLORAN needed?

Are the Russians and Chinese ahead of the West as stated in the Proceedings Article?

[etudiant]

In this month's US Naval Institute monthly magazine is an article about the need for a ground based replacement for Space based GPS navigation and Time Signalling in the event of War breaking out.

The Russian doctrine assumes all Space based systems shall be made Combat In-effective and are taking measures to provide backup systems.

Traditionally, the US Coast Guard provides navigational systems for the US DOD and ran the legacy LORAN-C system for Fifty Two Years before ending that program in 2010.

There is a proposal for the creation of a new eLORAN system to be operated by the USCG among requirements that it be deployable to combat areas when needed to replace losses of GPS coverage.

The article reports the Russians have used GPS disruption tactics in Syria and the US Military has also done similar actions at various times.

If Western Militairs, including the RAF and RN along with the US Forces were to lose all use of GPS Navigation services and its knock on uses.....are we prepared for that contingency?

Is eLORAN needed?

Are the Russians and Chinese ahead of the West as stated in the Proceedings Article?
Is eLORAN any less jammable than GPS? I'd wonder about that. Plus the emitters will be stationary targets.
Where is the advantage?

[SASless]

Along with eLORAN.....might we see a return of something called eDECCA?

or....CONSOL Radio Systems?

[Saintsman]

Youngsters these days have no map reading skills. They rely on GPS to get where they are going, whether it is a satnav or more likely, their phone.

Admittedly they are very good at finding places using them, but going back to basics might prove a challenge for most of them.

[vascodegama]

I am happy to lend out my sight reduction tables-very good rates. Also ECM resistant.

[PPRuNeUser0211]

Youngsters these days have no map reading skills. They rely on GPS to get where they are going, whether it is a satnav or more likely, their phone.

Admittedly they are very good at finding places using them, but going back to basics might prove a challenge for most of them.

I agree, but I don't see a problem with this, so long as you engineer resilience into your system (in a military context). Flying hours are finite (borderline non-existant in some fleets) and priorities have to be decided. There are a shed load of other skills that compete for attention and the answer is to ignore clock>map>ground or other traditional methods, and I don't see that as a bad thing given the limitations.

[Less Hair]

Today you can have databases for terrain and coastlines that don't change even after SIOP. Plus you have got the stars to navigate. Somewhere I read the USN is polishing the sextant skills of their young sailors again.

[gums]

Salute!

What a change in just 50 years. Number one was incredible accuracy of our clocks.

The "longitude problem" was a bear. The lattitude easy peasy. So the navigators from the middle ages to nearly the 20th century had trouble knowing how far east or west they were. With the watch I wear now, those folks in 1500, 1600, 1700 would have no problem. And the reason our GPS we have in our cellphone is so great is we can deal with nanoseconds versus minutes!

I do not trust the satellite systems in war. But with the great INS systems we now have and super accurate clocks, I have a good feeling. Of course there are still doppler systems that are independent of radio and satellite systems.

Gums sends...

[SASless]

According to the USNI article, the writer states the Russians accept as a given space based Satellite systems shall be rendered inoperative and have plans to use alternative means to replace the space based systems.

One such system was identified as being the "Sprut-N1".

They also have their own version of LORAN called "Chayka" that has three coverage zones in operation with a focus on the far North to facilitate their High Arctic Operations.


https://rntfnd.org/2019/03/01/report-russian-navy-gets-new-precision-terrestrial-system-to-backup-gps-glonass-inside-gnss/

[gums]

Salute!

I happen to agree with the folks that rule out satellite systems after one hour of a big conflict. I can also imagine a few scenarios where both contestants might want to retain the sats, maybe in degraded modes to deny the accuracy of JDAM bombs, but good enuf for navigation within a half mile or so.

I do not like depending upon the powerful LORAN systems, as their base stations could be easily targeted and destroyed.

I flew with a cosmic nav system in one of my previous lives, and as good as the doppler component was, it had some problems when over water due to ocean currents. For short flights, no problem for nav, but nothing like the current GPS bombs for putting one down in the warlord's tent. I did work with the fellows developing the original JDAM here at Eglin back in early 90's. The test bombs averaged about 4 and half meters using garage breadboard ciruits and such!

Doppler systems are great, but also radiate. So kiss off LO tactics withjout super planning and such, and zero bomb guidance like JDAM.

As an experieced war planner that has flown two extremely advanced avionics systems ( one in combat), a future air force must continue to develop and employ self-contained systems for nav. The super precision sat bombs and missiles will likely not be there for the "big" show, IMHO.
.
So practice DR nav and manual bombing. However, and a big one.... the inertial bombing computers are great for the very short time frames they are used to generate velocities and attitudes. A few knots of drift are not a problem during a weapon time of flight. Further, the new algorithms and filters can greatly improve the performance of navigation inertial systems that are not like the ones we had 50 years ago with the "stable table" and complicated gyro platform with its accelerometers.

Good discussion here, but I still think the hackers will be a problem for the satellite folks, and then there's the actual physical and electronic attacks.

Gums sends...

[condor17]

Gums et al , may I commend to you ' Longtitude ' by Dava Sobel . ISBN 1-85702-502-4 . USA publisher Walker Pub. Co. UK one is Fourth Est. Ltd.
Dedicated to her mum .. ' A four star navigator who can sail by the heavens , but always drives by way of Canarsie ' .
Before 'pooters , I always meant to write her ; to let her know we navigated over the pond using INS ' Triple Mix ' . [ which relied on a microchip clock , I think ] but also ' drove by way of Canarsie ' to get onto Rwy 13 L/R at JFK .

Fascinating thread , please keep tales coming .

rgds condor .

[BEagle]

I see that the mini-helicopter on Mars uses a blend of gyro inertial reference, corrected by terrain scanning to allow for gyro drift rates...

Unfortunately there was a software glitch which caused the terrain scans to be processed out of synch with the inertial system, causing violent oscillation until the terrain scan was disabled. The helicopter landed OK, but had used a lot of uneccessary power due to the nav errors.

TERCOM has moved on a long way since it first came into existence, as have optical sensors and system memory. With occasional rad alt updates, TERCOM aided INS looks like a good potential on board system?

[NutLoose]

I was reading an article the other night on the downing of Yamamoto re accurate navigation..It was Palm Sunday, April 18, 1943. But since there were no religious holidays on Guadalcanal, we took off at 7:15 am, joined in formation, and left the island at 7:30 am, just two hours and five minutes before the planned interception. It was an uneventful flight but a hot one, at from 10 to 50 feet above the water all the way. Some of the pilots counted sharks. One counted pieces of driftwood. I don’t remember doing anything but sweating. Mitchell said he may have dozed off on a couple of occasions but received a light tap from “The Man Upstairs” to keep him awake.

Mitchell kept us on course flying the five legs by compass, time, and airspeed only. As we turned into the coast of Bougainville and started to gain altitude, after more than two hours of complete radio silence, 1st Lt. Douglas S. Canning––Old Eagle Eyes–– uttered a subdued “Bogeys! Eleven o’clock, high!” It was 9:35 am. The admiral was precisely on schedule, and so were we. It was almost as if the affair had been prearranged with the mutual consent of friend and foe. Two Betty bombers were at 4,000 feet with six Zeros at about 1,500 feet higher, above and just behind the bombers in a “V” formation of three planes on each side of the bombers.

[SASless]

As the Mod's have to read all linked material....I shall only describe an Article I found very interesting about the early days of aerial navigation over long distances or over water by Lindberg, Weems, and others.

I recall reading with great. interest about the proving of Air Mail Routes and other aviation ventures like Immperial Airways and Pan Am Airways.

Lindberg used a very simple Dead Reckoning System to navigate and made landfall within a few miles of his intended point of arrival....after about 30 hours of flight with no sleep and no auto-pilot of any kind.

His accuracy was amazing...but what helped was a unique situation over the North Atlantic where the Winds worked to create a near zero drift situation.

Lindberg later got lost on a night flight over th waters south of Florida and nearly became a statistic common to early aviators....running out of fuel and landing in the water.

The first attempt to fly to Hawaii from California by the US Navy ended that way and the Sea Plane crew finished the. trip by sailing the airplane several hundred miles to the islands....which took them ten days.

The article can be found in the February 2013 Edition of the Air and Space Magazine under the title "In the 1920's Only One Man Held The Key to Aerial Navigation" and is an interesting account of how US Naval Aviation was instrrumental in improving Aeronautical Navigation and the role that a Naval Officer named Weems played in that.

[gums]

Salute!

Great stuff so far.

I thot TERCOM was a winner, and it, or its brother, seemed to do well certain applications like cruise missiles. I was flying the SLUF at the time and on one flight from Hicham to Guam I did not fully align the INS and flew for about 11 or 12 hours in the "doppler air mass mode" using predicted wind, the doppler and the air data computer for TAS. After all that time I was between 5 and 10 miles off, as the doppler was detecting ocean currents. Wasn't worried about getting lost as was with 5 other SLUF's and a KC-135 tanker, heh heh. Trust me, Amelia would have loved that!

Problem with TERCOM is it emits. True, the enema has to have a reciever underneath the missile flight path to detect it, but the less you emit the better.

If you can "see" a star in daylight, as this new system claims, we have a great solution to the "longitude" problem due to our cosmic, new clocks. Still have clouds and storms, but those stars can't be jammed and won't be put out of action at the initial strikes. BTW, my last job with Draper Lab was verifying performance of the Trident missile guidance system by flying it in an F-18 - yank the thing from a missile aboard the sub, fly it in a pod on the Hornet and gather/analyze data. It had a cosmic inertial, but just before launch they inserted the position of a star ( or two). After the stage quit and the "bus" floated free, the inertial shells about the gimballed sections rotated until a telescope could acquire the star. It then corrected the trajectory and the result was that a sub-launched missile from 4,000 n.m. away could put a nuke inside a soccer field. Gotta tellya, those guys at Draper were and still are very good.

Gums sends...

[condor17]

Gums , if you don't mind thread drift , not INS gyro drift ...
My ancesters were beach launching fisher folk on the North Norfolk coast . They reckoned that a compass worked really well whilst you were in sight of land ...Out of sight , it was useless.
By observation on a few years of Pond crossing . Westbound if setting initial course correctly from a VOR or waypoint ..to keep nearish to nav. flt plan ..just turn Left about 5 degrees every hour . Landfall won't be a million nm out .
Eastbound , no idea .. it was normally dark .

Please keep the tales coming , I'm learning a lot . But some is going straight overhead .

rgds condor .

[gums]

Salute!

Problem with the thousand year old compasses was they were not stabilized like we started to get in the 1920 and thirties. I do not unnerstan the offshore war stories, as the ones in my boats and others worked great, but unless stabilized, the ring floated about left and right and such... basic whiskey compass.

I only had one gyro compass failure in 4,000 hours, and had to use the whiskey compass. After violating some sensitive areas north of Nellis I caved in and asked for a gyro out procedure to reach my destination in California... maybe 30 minutes away. You know, "turn left, stop turn". "turn right, stop turn".

The biggie today is we have plenty of nav programs already in our watches and iPhones. With good algorithms and Kalman filters plus newer ones, you can calibrate your watch with position updates, so can correct for drift.

I would not bet my future on GPS or LORAN. I like the new sensors and nav programs that will still work when many navaids are toast.

Gums sends...