Inspired partly by bluechan's work in progress Goliath gun and partly by the Fat Gustav artillery piece from world war 2, I decided to try my hand at a build based around a massive cannon. Here is the result. It is a 10-wheel, mobile gun platform with the biggest gun I could make strapped in the centre, which can lob shells over to most other islands with relative ease.

Due to the weight of the gun, sticking it onto a hinge or two as an aiming system wasn't cutting it as the cannon would wobble for ages after aiming and after each shot, sometimes even breaking if the power was too high. I therefore used the front supports of the gun, with some strange hinge placement and some pistons, as the aim system. As such, the controls are a little odd - trim lifts the left support, VTOL lifts the right support, but steering should be used for the majority of the side-to-side aiming because pushing the gun over the limits of one support breaks it. Pitch is forward and backward and yaw is wheel turning. There is a stabilisation option if you want all your shots to go in 1 place - this is done by using throttle to activate the pistons on the underbelly of the vehicle, which when at maximum extension just barely lift the wheels off the ground. The downside of this is that there is much more recoil, and you will have to wait a few seconds for the gun to stabilise before firing again. For more rapid firing, you can let the gun slide back on its wheels, however if this is done too much you will fall off the runway. Due to its weight, there is no getting back on unless you add more engines.

As a side note, if you are planning on making any changes (which I am sure you are, and I encourage you to do so) don't forget to reset the trim/VTOL settings on the pistons, else you will have a gun that can only move up and down making aiming nearly impossible.

Unfortunately I am unable to work around the elasticity of the pistons which has been built into the game code - this causes a LOT of wobble when the gun fires, decreasing accuracy by quite a lot. Nevertheless, I was still able to knock out the bridge by Yeager airport from Wright airport, as well as sink the USS Beast and send a shell zipping between the mast and the main superstructure of one of the small destroyers, so maybe it’s practice. Edit: if you are in a rush or don’t want to bother with the difficult calibration and wobbly aim, reduce recoil to zero, barrel recoil to zero and take off the muzzle brake. It will still appear to wobble, but it will land in almost the exact same spot it predicts (out by a small enough factor to not matter) and by doing this I sunk the carrier from a Yeager Airport.

Have fun!