OK, I'm putting together a bunch of concepts for a interstellar military, one that sits between the Colonial Marines(Aliens) and the UNSC(Halo) in terms of technology and equipment. Lasers exist, but are used less by the interstellar forces due to the added complexity, weight, and reduced effectiveness on the planet they are fighting on which has a denser atmosphere with a large amount of particulates. Also because of this most fighting is a relatively short range. Most kinetic weapons are 'normal' by todays standards, and missiles and micro-guidance packages are considerably cheaper than today. Given that they have to lug everything across interstellar space a lot of the equipment and vehicles will be intended to fill multiple roles.
How effective, then, would a tank armed with a Vulcan(or similar) rotary cannon be?
I envision it as similar to the Merkava crossed with the Colonial Marine's APC. It would have decent armour, although maybe not as much as a MBT. Good mobility and speed, perhaps through wheels rather than tracks. And it would be able to carry a few soldiers(4 to 6) as well as its crew.
The idea behind using the Vulcan is that it can scale its firepower. Against a tank it fires on full auto, against lightly armoured targets it can fire burst mode. Also, if the turret is correctly designed it can also engage aerial targets. this should give it greater flexibility than a conventional MBT, although at the cost of making it less effective at being a tank.
The problems I see are the vulcan not being able to damage a MBT without the high angle attack it gets when used in a A-10 attack aircraft, and the turret being to heavy for effective anti-air work. The latter can be fixed with 'its the future! engineering!' but the former is more of a problem. Would it be more effective to have a dual or quad mounting of small bore HV cannons instead, perhaps light gas guns?
1) Would a armoured vehicle with a rotary cannon, and the ability to engage aircraft, be a more flexible option for a interstellar military than a conventional tank?
2) Would multiple HV cannon mount be better than a rotary design?