So in the suppliment Battlefleet Koronus it gives us a fairy interesting take on running large scale ground combat. My group just showed interest in starting up an army and taking more militiristic goals so I thought finally implementing these rules would be good. However I seem to have one issue. Now in ground combat all of the units speeds are measured in Kilometers and range from 20 to over 2,500 which… poses a bit of an issue with placing any sort of game mat down and tracking positions. At first I thought I'd just divide all the figures by a certain amount and convert the movements into units (much like voidship based combat is run) however units engae at a 1km range so the LCD would be 1KM, certainly not feesible for any sort of playmat. My question is has anyone found a solution to this?

I haven't run into this problem as of yet however I think there's a pretty easy solution for that.

Before deciding on a map scale look at all the units that will participate in this war. You'll probably have some infantry, some vehicles and some aircraft.
Probably the vehicles and infanty will move at roughly the same speed (with maybe the vehicles moving up to 2-5 times the speed of infantry) while aircraft are very very fast to say the least.

I'd then just use a scale so that vehicles and infantry movement can easily be represented on a map. Then decide where the aircraft are stationed (for example X kilometers off of that border of the map). Then you can use the aircrafts movement speed to determine their operational range / how long it takes for them to arrive from.

Also consider that most armies dont just have tank groups running off by themselves.So if you want your units to advance at roughly the same speed i dont think your stretching much there. This way you have everyone arrive at roughly the same time. Keeps things simple. As far as the aircrafts go i would just have them arrive on scene and do their thing and leave. If you needed your air battle to happen over your ground battle then simply designate different pieces for the air units and have the squares on your mat count for something different for them. That way if you need them to get involved with the ground battle at the same time you have a rough idea of how close they are and how long it will take for them to get there.