Basics:

The knee mortar can be used either in a direct or in an indirect way. You switch the firemode by scrolling your mousewheel.
While the direct fire method is very usefull to bombard buildings it of course leaves you in a dangerous situation since you need line of sight.

The indirect fire method lets you bombard areas from a completely safe distance. However it is very hard to hit anything without the knowledge of certain game errors.


Direct fire method:

Theres not much to say about this. Its basically a noobtube as you know it from games like BF3 or COD. However it is way more deadly.
It is best used to bombard buildings or areas with some kind of height behind it for the obvious reason that its way easier to hit.


Indirect fire methog:

Now this is the reason why I wanted to make this guide. It seems no one at all knows how to use the mortars indirect fire mode correctly.

There are two important things to know about the mortar to use it effectively:

1. The range you set in the mortar is not the range that is displayed ingame. Theres a factor involved that alters the distance. This is in my opinion the number one reason for the many teamkills and obviously a bug. (It seems the developers where not good enough at using the mortars themselves or they would have found this bug)

The range you set in the mortar is altered as followed: A range ingame of 166 meters is the equivalent range of the mortars 190 meters. This means:
190 mortar meters = 166 ingame meters
180 mortar meters = 157,25 ingame meters
170 mortar meters = 148,53 ingame meters
and so on.

2. The grids on each map have different sizes. One would think the grid size would be standardized by 100 meters but they are not...

Heres a list of the grid sizes for each map:

Kwajalein:
Grid size of 70 ingame meters = 80,1 Mortar meters

Hanto:
Grid size of 60 ingame meters = 68,7 Mortar meters

Pelieu:
Grid size of 50 ingame meters = 57,23 Mortar meters

Iwo Jima:
Grid size of 40 ingame meters = 45,8 Mortar meters

Saipan:
Grid size of 45 ingame meters = 51,5 Mortar meters

Guadacanal:
Grid size of 85 ingame meters = 97,3 Mortar meters

Betio:
Grid size of 78 ingame meters = 90 Mortar meters (approximately - I just tested it alone so its not really accurate for this map)


3. It is also interesting to note that the mortars indirect fire mode is EXTREMELY ACCURATELY. If you know where an enemy is located and you got its accurate distance and angle towards you then its a sure kill. However how you all know it is hard to know the exact positions of enemys. A good understand of the map and surveillance is important to use the mortar effectively.

Also I suggest you use a ruler + a simple calculator to arrange your aim and calculate the exact distance on the fly. I got 20+ kills in one round on Hanto only with the proper use of the map and by bombarding certani favorited defending positions.

4. AOE damage. The mortar seems to have a rather small blast radius. You may hit several enemys but for a one hit kill they need to be relatively close to the impact it seems.

5. You want to aim in the middle of the screens while using the mortars indirect fire mode because you can alter the range to a certain degree by shifting your aim up and down. Funnily it seems you can only decrease the range by this and not increase it.



So now go bring havoc over your enemy! And dont forget where you got your information from!

Greetz!;)