Combat Weather Forecasting

Submitted by Eric Daniel

“All stations this net, this is Charlie Niner-Two, stand by for air temp and pressure update, over.”

In Armor, weather updates are a critical element to the tank’s fire control system.  While the FCS can automatically sample some data, such as wind speed, inclination, and turret traverse rate, it can’t tell what the ammunition temperature, air temperature, and barometric pressure are.  In these cases it’s up to the crew to manually enter this data.  In the case of ammunition temp, this is simply a matter of reading the temp off the ammunition temp gauge, but getting air temp and baro pressure require outside assistance.  In peacetime, this data can be had from the tower (C92) or the TOC, both of whom get the information from Range Control.

What do you do, though, if you’re in combat, on the attack, and there is no tower, and there is no range control?  In 1991 we learned that you “just run with it.”  The Army has published “fleet” values published in the back of the tank’s TM (Technical Manual) for baro pressure and temperature for given months of the year and regions of the globe.  Unfortunately, these values can be wildly off base.

Our solution was to invest $50 in a wall mounted “weather station” from the PX.  The three instrument “station” had a clock, a thermometer, and a barometer, all bolted to a wood plaque which, conveniently, fit right behind the GPS “doghouse” and was visible through the TC’s (tank commander) FUP (Forward Unity Periscope, the big vision block in the front of the TC’s cupola.)  With our handy dandy weather station we were able to enter in relatively accurate (the barometer was analogue while the FCC accepts inputs to the hundredths so some guesstimation was required) values for the air temp and pressure.

Well, times have changed, but the need for weather data has not.  Fortunately, advances in technology have made portable weather stations cheaper, more accurate, more durable, and with a number of features ours didn’t have.

The Coghlan’s wireless weather station, for example is completely weather resistant, driven by a lithium battery, and is capable of sampling air temp, air pressure, humidity, heat index, and it can make local weather forecasts based on the previous 8 hours of sampling data. If you put the base unit in the ammunition compartment (hang the remote sensor outside) you can use it as a back up ammunition temp sensor as well.

Another option is the La Crosse Intelligent Forecast Station.  This unit, in addition to the features offered by the Coghlan unit, is also capable of predicting frost, fog, and snow, as well as “real-time” weather forecasts based on a 12-hour data sample.  The La Crosse unit also keeps time through an Atomic clock signal receiver, which makes it’s time keeping extremely accurate.

Comments

[czecho]

Nice concept, I like it!
But: Have you been able to verify the RESULTS? Would it be profitable to test it against the weather reports at the range and again against the more generalized weather reports in the real world? Just curious.

[Eric Daniel]

Czecho,

In reality, from an armor perspective, all I'm really interested in is the air temp and the barometric pressure. The rest of the "forecasting" features offered by these instruments are nice, but not really mission critical. As for measuring how well one of these remote devices stacks up against the information provided by range control, I've never noticed any real deviation (+/- a degree or two or a few hundredths of a mm Hg.) Something to keep in mind too is the fact that the actual location of the sampling station can be miles from your location (some tank ranges have the sampling gear there in the tower, while others have the data station at range control, which can be miles away.)