Why on the MARS-One....
 

... are there two fixed, forward firing .50 cal machine guns? Are we to believe that for covering fire the driver is going to continually yaw the nose? Am I missing something?

Sigh, I blame James Bond movies and the movie "Damnation Alley".

I don't use the MARS one at all. It could not work since the blue prints make no allowance for the internal space all those systems and weapons would take up.

Interesting note the "Damnation Alley" vehicle did drive and float. I think there is even some Youtube videos of it in motion.

Yeah, right here.

I have some blueprints for the MARS-One, but I don't remember there being the fixed .50cal's only the fixed 81mm mortars.

However, I agree, the mortars are not a good idea for there, I do have my own plans for it, but at a push you can fit quite a bit into the turrets on that vehicle.

The forward and rear firing mortars are not listed as fixed. Here is a simplified listing of weapon direct from the 3rd edition description:

Weapon systems are mounted as follows from bow to stern:
1x forward firing claymore mine
2x forward firing fixed M85C machinegun
2x forward firing 81mm mortar*
1x turret mounted 81 mm mortar*
2x turret mounting M85C machinegun and M10-8 flame gun
2x turret mounting Rh 202 20mm autocannon
1x heavy weapons pod A or B (choose one)
2x rear firing 81mm mortar*
2x rear firing M85C machinegun
1x rear firing claymore mine

4x left firing claymore mine
4x right firing claymore mine

* all mortars are breach loaded

I have always thought it was a typo, since the rear firing M85Cs are NOT fixed and the all the M85Cs were in some kind of limited arc, servo actuated pintle mount with an overlapping cone in the center. It is also possible they were trying to make something like this: http://pcf45.com/misfire/81-50.html

My question was just to see if there were any real justification for a fixed mount on a ground vehicle.

The Stridsvagn 103 uses a fixed mount. Of course if has a very flexible suspension controlled by the gunner, but they are possible.

M85's SUCK, but they have a short receiver. a pop out remote mount would be good, if there was room.

My favourite oddity is the MARS command centre with all the radios etc has an 81mm mortar firing in the middle of it. Must make radio communications a chore.

The current version is ridiculous, but perhaps something closer to a land based version of an armoured train. The Russian's and Croats were using these until the 1990s. Much bigger with dedicated artillery and only a few defensive guns to prevent it getting over run. Combined with rail cars carrying parasite armoured vehicles to be driven under cover right upto the enemy and then released. Combine this with some drones or gyrocopters and it becomes quite a serious weapon. Being able to fire and aim artillery for kilometers around spot enemy and move it's self out of range of attack.

If was doing all this off of a rail road track it would also be insanely expensive.

A couple of HumVee's with S250's or M35 van bodies with escort vehicles makes more sense. Or even a tractor trailer like the fleet Reagan created. This would definitely make them wanted by every Gypsy Trucker group!