I'd use the "side" of the vehicle as its fire-arc. I just assume that whatever I shoot can shoot back and hit my flank armor. And another way around.

 

It isn't a sponson or turreted weapon so it has a fire arc of 45 degrees from each end of the array (since the array as a whole is a weapon). Though it could be argued that each gun in each array is separate because of the text "...all guns in the same array..." Regardless, they are all fixed guns so 45 degree arc.

 

According to BRB hull mounted weapons have strict 45 degree arc. Hull mounted weapons are basically those that are bolted to the hull and don't look like they have any room to traverse. The gauss flayer array doesn't LOOK like hull mounted, but rather each of them is mounted on their own pintle-mount.

 

It may not look hull mounted but there isn't any mention that it's pintle either. Guess we'll have to wait for the FAQ.

 

Man, never though of it this way. I agree with the above that if you look at the model they are modelled to look like the 'move' the rounded edges and such. But thanks for pointing this one out. Since the flayer is along the whole thing the 45' thing is kinda a small point as it starts 45' from front, and then 45' from rear flayer which is a huge spread. But yeah, shooting forward would be sweet.

 

the text also says that the arrays MAY fire at a different targets than the main cannon on the doomsday ark, would that suggest that they can fire in its front facing arc?

 

I dont think so, if anything that would tell me the arrays are less likely to shoot from the front arc. If they could do that, then they might not have gotten the rule to shoot separate targets.

Buddies and I have been doing it 45* fire arc, but thats just because we have no idea what else it would be.lol

 

Even if you give them 180 degree arc of fire the arrays still could never shoot the same target unless the target was very wide and right in front of it. The 180 degree is measured from the weapon not the centerline of vehicle.