Tailored IFV/MBT for enviroments

[Master of Cards]

I had a thought while reading the Tailored IFV thread. Would there be a general use IFV/MBT for space armies? Assuming you actually had to land on a planet, why would there be a general use vehicle? The various planet environment would force too many comprises into the design I think to make a general use platform.

But how would rapid response forces work for inter system reenforcement? Would a group with a water world, a Venus World and a large plains world have three types or what?

[Purple]

Well presumably it would have to be fully amphibious like the BMP-3.
It would also have to be light enough to be delivered by air easily.

The best option might be to have a general platform used for something like the chassis and have everything but the chassis and the engine be modular.

That way you could have a vehicle that you can use in a multitude of situations without having to produce many different types of vehicles. From an economic standpoint it sounds rather appealing.

[Cykeisme]

Not to derail, as it's somewhat related, but this is something I've always wondered.

How much oxygen does a modern internal combustion engine need? I realise there will be other issues, such as not getting adequate cooling in the absence of from atmospheric convection and likely other issues too, but disregard that for a moment. How much liquid oxygen (ratio-wise to petrol fuel) would you need to carry on a vehicle with a design similar to a present-day terrestial vehicle to get it to run in an oxygen-free environment?


I would expect that an interplanetary army would, as a requirement, need their vehicles to be able to operate regardless of local atmospheric composition. Logically, if their tech level had achieved convenient interstellar travel, they'd probably have electrical cells with really high energy density, or miniature fusion reactors or something high tech and cool. But if we had to go ICE, is it practical for a land vehicle to carry its own oxygen?

[Sea Skimmer]

A lot of specialist armor is likely to exist, if any compelling reason exists to fight on the surface of strange alien worlds. After all the earth today supports hundreds of different AFV designs in service at the same time, and a united planet could could away all the clearly redundant types, field more specialist designs, and still come out with a simpler more economical ground military then all the earth's nations thrown together today. I'm just not very convinced that sending tanks onto an alien world would ever happen, at least past the scale of handfuls of them. I tend to think of far future AFVs of being more like an armored network hub, that happens to have some kind of indirect fire weapon to kill targets it drone swarms find 50 miles away.

Not to derail, as it's somewhat related, but this is something I've always wondered.

How much oxygen does a modern internal combustion engine need? I realise there will be other issues, such as not getting adequate cooling in the absence of from atmospheric convection and likely other issues too, but disregard that for a moment. How much liquid oxygen (ratio-wise to petrol fuel) would you need to carry on a vehicle with a design similar to a present-day terrestial vehicle to get it to run in an oxygen-free environment?

Gasoline burns optimally at a 14.7:1 air fuel ratio. Air is about 20.9% oxygen, so you would need a roughly 3:1 ratio of LOX to gasoline. The ratio for a complete burn of diesel fuel is similar, though a diesel can operate over a wider range of conditions and lower idle ratios then a spark ignition engine. Anyway ignoring storage and cooling issues, the resulting vehicle would only travel about 25% as far as it did before it needed refueling. Of course other factors like how much gravity the planet has could also have a huge effect on fuel economy.

Another option would be some kind of liquid monofuel with its own oxidizer already mixed in, like nitromethane. This would make for a much simpler engine that is quite high performance, torpedoes are commonly powered by monofuel combustion engines, but such fuels do have drawbacks in cost and how easily they explode.

Nuclear power, fuel cells, and batteries would also all have applications in the future. LOX and Hydrogen would likely be the ideal fuel though, for the simple reason that you can then turn any source of water into fuel using a mobile nuclear powered cracking plant landed from orbit. This beats hauling petroleum products between the stars... unless you fight on a desert planet that doesn't even have icecaps.

I would expect that an interplanetary army would, as a requirement, need their vehicles to be able to operate regardless of local atmospheric composition. Logically, if their tech level had achieved convenient interstellar travel, they'd probably have electrical cells with really high energy density, or miniature fusion reactors or something high tech and cool. But if we had to go ICE, is it practical for a land vehicle to carry its own oxygen?

Maybe, maybe not. Why bother fighting on the ground over worlds with air you can't breath when you can just go to another planet or even a different solar system? If the world has no air at all meanwhile, then you would have an utter shooting gallery from space and could attack from orbits as low as you want. its certainly practical on paper though, for a land vehicle to haul around O2. Even 1/4th the range of current tanks would give you maybe 100 miles of cruising radius which is enough to accomplish a mission. A hybrid setup with batteries would also ensure that less energy is wasted at idle, though once more at the cost of a yet more complex engine setup.