Vehicular Land Navigation System C1

[David Dunlop]

That's the direction I was leaning in as well, Terry.

Possibly an entirely new concept, or an evolution of the wartime two dimensional plotting system developed by the US Army that I have seen installed in the MB/GPW.

Maybe the postwar Canadian system was planned for the Ferret?

Interesting, Richard. The US wartime equipment took up quite a bit of space in a jeep. Might have been a challenging install for a Ferret, but heavier armour may not have been such an issue.


David

[Richard Farrant]

Originally Posted by David Dunlop

That's the direction I was leaning in as well, Terry.

Possibly an entirely new concept, or an evolution of the wartime two dimensional plotting system developed by the US Army that I have seen installed in the MB/GPW.

Maybe the postwar Canadian system was planned for the Ferret?

Interesting, Richard. The US wartime equipment took up quite a bit of space in a jeep. Might have been a challenging install for a Ferret, but heavier armour may not have been such an issue.


David

David,
If you have seen a mine flail working, there is no way you can visually see where you are going, to this gyro system would have been the cutting edge at the time.

[BCA]

David: the WW2 jeep navigation system was the Land Odograph. It integrated compass direction with distance determined by the speedo cable. I have most of what I believe is the system that you refer to as used in the Centurion. There is a mechanical plotting board to plot the course on a map. A couple of years ago there was further discussion of the Canadian system here on the forum...Brian

[Ed Storey]

Continuous display of the position of the vehicle was obtained by automatic dead-wreckoning. Distance travelled was measured by the speedometer and direction was measured by a compass. A computer automatically calculated the positon of the vehicle which was displayed on a map or by a digital readout. The complete unit could be mounted in a Ferret, M113A1 or Centurion.

Navigation Set Land Vehicular C1.jpg

[David Dunlop]

You continue to amaze, Ed! Thanks for posting that!

Who built them and when, and how long was the system in service?


David

[Lang]

The direction indication would only have been reasonably accurate for an hour or so before resetting due to gyroscopic precession (caused by drag on the gyro bearings among other things) but this would normally be enough for most purposes. In a steel vehicle it would be almost impossible to fit a remote magnetic compass (as in aircraft) to feed continuous updates to the gyro to correct the drift.

Where they got their correction from I can only guess - the most obvious is for someone to stand well back from the metal mass of the vehicle with a prismatic compass and call out the centreline direction to be wound on to the indicator. If you were really stuck inside for long periods an educated guess could be taken from experience with that particular instrument to wind on 10 degrees, or whatever, East or West every hour.

The beauty of a gyro system is you can put anything you want on the dial so you can have true bearings to read straight off the map without worrying about magnetic variation calculations.

I think they were probably meant for circumstances such as an assault on a pitch black night or if you needed to be closed up (Churchill?) for comparatively short periods.

Lang

[Grant Bowker]

The EME instruction to install the "NAVIGATIONAL SET, Land Vehicular, C1" in the M38 is dated July 1963. My copy came with several other EME instructions M38 and M38A1. There wasn't a similar instruction for the M38A1 in the bundle. I don't know whether that was because it was never done (obsolete???) or if the same instructions were used (seems unlikely as there were other mods where separate sheets existed).
The NSN for the Nav set was 6605-21-111-1843.

[Ed Storey]

The Navigational Set, Land Vehicular, C-l, (NAVAID) was developed to provide a self-contained navigational aid, independent of radio assistance, which would give positional and navigational information to commanders of vehicles in armoured and other units under the following conditions:
(1) Closed-down, during mobile operations by day or night, and under nuclear threat conditions.
(2) During conditions of darkness and poor visibility, e.g., fog and smoke.
(3) On featureless or poorly mapped terrain, including the Arctic.

Despite the ease of operation and advantages that were provided by the NAV AID, the art of map reading was still of primary importance and was not to be neglected.

The equipment did not require radio assistance for its operation and by using a gyro-compass it is was affected by variations in the earth's magnetic field or in the magnetic characteristics of the vehicle.

This device was designed to indicate the location of vehicles to within an average accuracy of 1 % of the distance travelled and the heading to within .75 degrees.

This device could be used in unmapped terrain. Under these conditions the· counters on the Indicator Heading and Position were set to an arbitrary reading and an X (representing the present position of the vehicle) marked on the plastic map holder of the Plotter with a china pencil. The vehicle could return to the original start point, after completing a mission, by the commander directing the arrow of light, which corresponds to the movement of the vehicle) toward the X until the arrow returns to the X. The counters were then checked to see that they reflect the arbitrary reading set at the beginning of the mission.

The NAVAID could only be used maps with scales of 1/25,000; 1/50,000; 1/100,000 and 1/250,000. Prior to the first run of the day, the Compass required an initial 30 to 60 minutes warm-up and settling period. The compass had some difficulty maintaining its design accuracy at the higher speeds encountered in road travel. When moving over hilly terrain, the actual distance travelled on the ground is greater than the distance travelled
on the map. Therefore, periodically, the actual heading and position on the ground had to be checked against the heading and position displayed by the NAVAID. If there was a variation appropriate adjustments had to be made.