Navigation?

[Adam106]

This may seem like a silly question but how did / do modern MBTs and IFVs handle navigation?

Coming from a flight simulation and real life commercial pilot perspective I'm very familiar with the various forms of aircraft navigation. Radio aids - VOR/DME, ADF, ILS etc, internal aids like INS's and IRS's and of course GPS are used by aircraft, not forgetting map, compass and stopwatch.

I'm guessing basic map reading is the the main form of navigation used. Most modern AFV's must have access to GPS though - which ones? - only those with 'electronic map displays'? How many AFV's have datalink these days? Do modern tanks have compasses integrated to the vehicle or do the crews rely on a handheld compass?

Anyone know the first MBT to have an integrated GPS - I'm guessing M1A2?

[12Alfa]

Most armies have hand held GPS's, so if the AFV does not have it built in, or a interface to accept hand held the crew will use the map .

[Retro]

Do modern tanks have compasses integrated to the vehicle or do the crews rely on a handheld compass?

You don't want to use a hand-held compass if you're sitting in a 30+ ton piece of metal

[Adam106]

You don't want to use a hand-held compass if you're sitting in a 30+ ton piece of metal

Yes, exactly. Although if the compass is fixed to the vehicle - surely could you 'swing' the compass and then apply a deviation?

[Rotareneg]

I'd assume it'd be pretty tricky to systematically correct for any deviations as the vehicles magnetic field would surely change with different turret/hull angles.

[Ssnake]

Operation Desert Storm was the first time that ground forces were equipped on a somewhat larger scale with GPS receivers and navigation devices. Needless to say, land navigation before and after were never the same again (as long as the GPS receiver works).

It then also depends on what kind of a landscape you have. It's a major difference if you have a featureless desert that stretches for a hundred miles or more, or if you are in highly restrictive mountain terrain, or in a jungle where you neither receive a clear satnav signal nor can see much farther than maybe one or two dozen meters ... or if you are in a highly urbanized, domesticated landscape with a dense road network like what you'd find in Germany and its neighboring countries. The more details the landscape offers, the better your average visibility, and if you have a high quality map of your area of operations, the less dependent you are on a functioning GPS. Obviously.

[Adam106]

hmmmm...good point, Rotareneg. I didn't think of that. The proximity of other vehicles may also effect it. Aircraft tend to be pretty isolated in flight.

[pii]

So how do you know which way is which in SB? I'm just learning and I'm totally lost as to where north, south, east or west is when I'm in the tank. Am I missing something? I hear the tc say tank north but I have no idea where north is.

[12Alfa]

I do and it works well, I just insert the GPS into the cradle and turn it on, the veh ant does the rest.

[12Alfa]

So how do you know which way is which in SB? I'm just learning and I'm totally lost as to where north, south, east or west is when I'm in the tank. Am I missing something? I hear the tc say tank north but I have no idea where north is.

Red turret, bottom right of screen point in a compass direction:eek2:

[12Alfa]

Yes, exactly. Although if the compass is fixed to the vehicle - surely could you 'swing' the compass and then apply a deviation?

A GPS is NOT a compass, its a receiver from the signal being sent in orbit, metal does not effect it like a compass:sonic:.

[pii]

Red turret, bottom right of screen point in a compass direction:eek2:

Not sure what you mean but I'll look for it when I fire it up later. Do you see it when you are viewing through a sight?

[Rangoon]

Not sure what you mean but I'll look for it when I fire it up later. Do you see it when you are viewing through a sight?

It's a red outline of a tank when viewed from above. You see the hull facing one direction, the turret potentially another, and a yellow dot showing your current view direction (whether TC, external, whatever). North is up, so if the hull is facing left, the turret is facing up, and the yellow dot right, your Tank is facing West, your Turret is facing North, and you are looking East.

HTH!

[pii]

It's a red outline of a tank when viewed from above. You see the hull facing one direction, the turret potentially another, and a yellow dot showing your current view direction (whether TC, external, whatever). North is up, so if the hull is facing left, the turret is facing up, and the yellow dot right, your Tank is facing West, your Turret is facing North, and you are looking East.

HTH!

Oh. Lol that little tank needs to be bigger. But thanks that will certainly help.

Now what does HTH mean?

[Rangoon]

HTH = Hope That Helps.

Also, I think the view dot is white, not yellow...hard to tell; it is small.

[12Alfa]

Not sure what you mean but I'll look for it when I fire it up later. Do you see it when you are viewing through a sight?

Yes

[Adam106]

A GPS is NOT a compass, its a receiver from the signal being sent in orbit, metal does not effect it like a compass:sonic:.

Err yes, I'm aware of the difference between a wet compass and a GPS. :lol: The point was about the idea of a standard whiskey compass being affected by the magnetic field of the vehicle and a correction (compass deviation) being needed.

Can anyone with first hand knowledge comment on the use of compasses with large AFVs and procedures to apply correction?

[Andrimner]

Well. I have 10 years of first-hand knowledge of navigating on armoured vehicles, but we never used compasses - never brought a compass near my tank. Specifically for the reasons mentioned above. I never tried using a compass, I just accepted the idea that that was unfeasible. In the first few years we got by on maps alone (not so hard when you're used to it), and eventually we received vehicle-mounted GPS which gave us the grid. And then BMS came along.

[Ssnake]

Well, from what I read in the book "The Eyes of Orion", you take the bearing to a distant target, e.g. you park another tank 3km away from your position. Then you take the bearing with the compass from your commander's hatch. Then you dismount, walk 50...100m towards your reference point (that tank in the distance), and take another bearing. The difference between the two is your magnetic deviation; the opposite of it is your correction factor. Apparently this worked well for months during Desert Shield until they received a few GPS receivers more or less at the last minute before the beginning of the ground offensive. The shifting of the VIIth Corps was apparently managed by the troops without GPS devices, and still they managed find their way in the desert. It required quite some precision in measuring bearings and distances - clearly impractical in combat situations - but it could be made to work.

In principle, if you have a precise watch at your disposal, which is less of an issue today than it used to be centuries ago, in principle you could still work with a sextant when in the desert (provided that you know how to work with it and if you have tabulated ephemerides at hand).

[MAJ_Fubar]

It is possible to use a standard compass from the top of a tank, but your experience may vary. Although we had an early GPS unit on my track during the first Gulf War, it was often inaccurate due to a poor built-in antenna. At one point we were forced to dead reckon at night with just a compass and some NODs after becoming separated from the rest of the troop - not fun at all, but it did work...as long as you keep the compass well above the turret top. Still, basic tank navigation is all about terrain association, knowing where you are before you start, and having at least general idea of were you're going.

[Adam106]

Well. I have 10 years of first-hand knowledge of navigating on armoured vehicles, but we never used compasses - never brought a compass near my tank. Specifically for the reasons mentioned above. I never tried using a compass, I just accepted the idea that that was unfeasible. In the first few years we got by on maps alone (not so hard when you're used to it), and eventually we received vehicle-mounted GPS which gave us the grid. And then BMS came along.

Well, from what I read in the book "The Eyes of Orion", you take the bearing to a distant target, e.g. you park another tank 3km away from your position. Then you take the bearing with the compass from your commander's hatch. Then you dismount, walk 50...100m towards your reference point (that tank in the distance), and take another bearing. The difference between the two is your magnetic deviation; the opposite of it is your correction factor. Apparently this worked well for months during Desert Shield until they received a few GPS receivers more or less at the last minute before the beginning of the ground offensive. The shifting of the VIIth Corps was apparently managed by the troops without GPS devices, and still they managed find their way in the desert. It required quite some precision in measuring bearings and distances - clearly impractical in combat situations - but it could be made to work.

In principle, if you have a precise watch at your disposal, which is less of an issue today than it used to be centuries ago, in principle you could still work with a sextant when in the desert (provided that you know how to work with it and if you have tabulated ephemerides at hand).

It is possible to use a standard compass from the top of a tank, but your experience may vary. Although we had an early GPS unit on my track during the first Gulf War, it was often inaccurate due to a poor built-in antenna. At one point we were forced to dead reckon at night with just a compass and some NODs after becoming separated from the rest of the troop - not fun at all, but it did work...as long as you keep the compass well above the turret top. Still, basic tank navigation is all about terrain association, knowing where you are before you start, and having at least general idea of were you're going.

Thanks guys. Really useful stuff:). Out of interest what kind of magnitude deviation might be experienced with say a Abrams / challenger type tank? More than 10 degrees?

[Tacbat]

Navigated by features. Easier to tell the driver where to go.

[Ssnake]

Thanks guys. Really useful stuff:). Out of interest what kind of magnitude deviation might be experienced with say a Abrams / challenger type tank? More than 10 degrees?

No, nonono. You can at least navigate to about 5° precision; if you're careful and precise, less than 3°. Of course, even 3° can add up if you're forced to use dead reckoning for an extended time, and the odometer - while being much better than counting steps, isn't exactly a high precision instrument either.

[Adam106]

No, nonono. You can at least navigate to about 5° precision; if you're careful and precise, less than 3°. Of course, even 3° can add up if you're forced to use dead reckoning for an extended time, and the odometer - while being much better than counting steps, isn't exactly a high precision instrument either.

OK that doesn't sound too bad. I'm used to seeing about 3-5 degrees in various aircraft. Because I hadn't experienced it, I figured that a 70 ton lump of steel would have a greater effect.

[Ssnake]

Well, those figures above are based on compass accuracy (after correction).