A question on Fission powered fixed wing support craft.

[Primus203]

The question is can these go into space like aerospace fighters.

[AlphaMirage]

No, support/conventional aircraft can only reach the lowest High Altitude level if jet powered. Likely it requires the air to generate thrust (via a ramjet or similar) rather than carrying sufficient remass to generate it like Aerospace fighters do

[cray]

If fission units could operate in space, they'd get a lot less fuel points per ton than fusion spacecraft. I think that might show up in the satellite rules.

[glitterboy2098]

Yep, basically why we also don't see ICE spacecraft to reflect chemical rocketry. Instead of thrust points per ton, you'd be looking at tons per thrustpoint.

[idea weenie]

Yep, basically why we also don't see ICE spacecraft to reflect chemical rocketry. Instead of thrust points per ton, you'd be looking at tons per thrustpoint.

And you'd likely have to recalculate the thrust rating after you burn every thrust point due to the sheer tonnage of fuel being used?  I.e. a 3/5 vessel has burned 25 tons of fuel, so that means it is now 4/6.

[cray]

And you'd likely have to recalculate the thrust rating after you burn every thrust point due to the sheer tonnage of fuel being used?  I.e. a 3/5 vessel has burned 25 tons of fuel, so that means it is now 4/6.

That's how I made my home rule chemical and fission fighter rules.

[RifleMech]

Does that happen for any other unit in BT?

[CloaknDagger]

The question is can these go into space like aerospace fighters.

Yes, actually.

If you look at Tac Ops rules for vacuum, conventional vehicles and support vehicles can operate in vacuum when they have environmental sealing and nuclear engines or batteries, and in the case of fliers, VSTOL equipment that they use to hover around.

It's an obscure rule, but a way to get around the regular restrictions. The trick is that non-ASF aren't really made to do re-entry, so you're effectively reliant on dropships and small craft to move your units back to a habitable planet afterward.

As for unlimited range in-atmosphere fighters, the rules allow propellers on fixed-wing support vehicles. Though I agree there should be something like a Project Pluto where a reactor itself uses the air as propellant.

[cray]

The altitude limit on conventional fighters and support vehicles generally hinders their ability to get into space regardless of propulsion.

[CloaknDagger]

The altitude limit on conventional fighters and support vehicles generally hinders their ability to get into space regardless of propulsion.

They work in vacuum, so you'd have to pretend there's a magical forcefield preventing them from flying away in that case. VSTOL equipment and environmental sealing already gives them the maneuverability they need to move without air.

[Daryk]

You have to be at least 3/5 to get out of the atmosphere.

[RifleMech]

Yes, actually.

If you look at Tac Ops rules for vacuum, conventional vehicles and support vehicles can operate in vacuum when they have environmental sealing and nuclear engines or batteries, and in the case of fliers, VSTOL equipment that they use to hover around.

It's an obscure rule, but a way to get around the regular restrictions. The trick is that non-ASF aren't really made to do re-entry, so you're effectively reliant on dropships and small craft to move your units back to a habitable planet afterward.

As for unlimited range in-atmosphere fighters, the rules allow propellers on fixed-wing support vehicles. Though I agree there should be something like a Project Pluto where a reactor itself uses the air as propellant.

Nice catch on the rule.
Going into space isn't clear but they can operate in a vacuum. If they can't fly into space themselves. they could hitch a ride and deploy from something that does.

[cray]

They work in vacuum, so you'd have to pretend there's a magical forcefield preventing them from flying away in that case. VSTOL equipment and environmental sealing already gives them the maneuverability they need to move without air.

The force field is a problem, but pretending there's a helicopter rotor that works in a vacuum isn't a problem? 

[CloaknDagger]

The force field is a problem, but pretending there's a helicopter rotor that works in a vacuum isn't a problem? 

VTOLs are interesting here because we know in universe there are non-bladed VTOLs, but we only have rules for bladed ones.

But we know jump jets work just fine in space when prepared for it, and VSTOL equipment is similarly just raw thrust, so I don't see any reason non-blade VTOLs couldn't be given the same treatment for vacuum operations.

[idea weenie]

VTOLs are interesting here because we know in universe there are non-bladed VTOLs, but we only have rules for bladed ones.

But we know jump jets work just fine in space when prepared for it, and VSTOL equipment is similarly just raw thrust, so I don't see any reason non-blade VTOLs couldn't be given the same treatment for vacuum operations.

Non-bladed VTOLS might work by basically pointing the exhaust or even the full jet engine down, similar to a Harrier or the GI Joe Sky Hawk.

So in order to use them in space you'd need to bring along plenty of oxygen, but at that point you are effectively making a chemical-propelled rocket that is trying to dogfight nuclear-powered 'rockets'.

[CloaknDagger]

Non-bladed VTOLS might work by basically pointing the exhaust or even the full jet engine down, similar to a Harrier or the GI Joe Sky Hawk.

So in order to use them in space you'd need to bring along plenty of oxygen, but at that point you are effectively making a chemical-propelled rocket that is trying to dogfight nuclear-powered 'rockets'.

It's weirder than that.

You can't use ICE in space, obviously, so that only leaves nuclear engines and fuel cells/batteries as options.

So it's nuclear rockets vs nuclear rockets.

Except... what are the pure electric units doing? Does Battletech have hilariously powerful ion engines or something?

There's also the issue of how Conventional Fighters are often using air-breathing fusion engines, which is why they get a fuel boost per ton, but since environmental sealing is required and that's a specifically optional rule, we can just assume that the sealing includes a switch to a normal ASF rocket engine.

[idea weenie]

It's weirder than that.

You can't use ICE in space, obviously, so that only leaves nuclear engines and fuel cells/batteries as options.

So it's nuclear rockets vs nuclear rockets.

Except... what are the pure electric units doing? Does Battletech have hilariously powerful ion engines or something?

Fuel Cells and Batteries are still dealing with an engine that is designed to push local air.  Space is a bit lacking in that category.  You could bring along compressed air, but at that point you are using a cold-gas thruster system that is a bit faster than merely opening the nozzle of the tank of air.

Nuclear engines would be turning the compressed into either a faster output than FC/B powered, or a modified Ion engine.

There's also the issue of how Conventional Fighters are often using air-breathing fusion engines, which is why they get a fuel boost per ton, but since environmental sealing is required and that's a specifically optional rule, we can just assume that the sealing includes a switch to a normal ASF rocket engine.

Sealing just keeps the internals of the CF intact, one of which is the pilot.  The ASF version of the engine might require the rest of the CF to be designed to handle the dedicated H2 fuel for fusing.  You'd also have to include the reaction nozzles to handle maneuvering in space, instead of using elevators, ailerons, rudder, flaps, slats, spoilers, trim tabs, canards, elevons, and any ruddervators to maneuver in an atmosphere.

By this point you effectively have an ASF.

[Daryk]

For the record, Battletech DOES have hilariously powerful ion engines.  That's what "station keeping" drives basically are.

[CloaknDagger]

For the record, Battletech DOES have hilariously powerful ion engines.  That's what "station keeping" drives basically are.

Since when?

I'm not aware of anything making station keeping drives ion engines, and their output is on par per ton and per ton of fuel with fusion engines.

Fuel Cells and Batteries are still dealing with an engine that is designed to push local air.  Space is a bit lacking in that category.  You could bring along compressed air, but at that point you are using a cold-gas thruster system that is a bit faster than merely opening the nozzle of the tank of air.

Nuclear engines would be turning the compressed into either a faster output than FC/B powered, or a modified Ion engine.

Sealing just keeps the internals of the CF intact, one of which is the pilot.  The ASF version of the engine might require the rest of the CF to be designed to handle the dedicated H2 fuel for fusing.  You'd also have to include the reaction nozzles to handle maneuvering in space, instead of using elevators, ailerons, rudder, flaps, slats, spoilers, trim tabs, canards, elevons, and any ruddervators to maneuver in an atmosphere.

By this point you effectively have an ASF.

Issue is that the vacuum rules don't account for fuel efficiency differences, so the electric engines have the same or better fuel efficiency as nuclear, which is silly.

An environmentally sealed CF with VSTOL isn't an ASF. They're different frames, comparable to CVs vs Battlemechs. ASF very specifically are full of myomer similar to Battlemechs. Vacuum rated CFs are still much more lightly built than ASF and simpler in construction.

[Daryk]

It's all fluff... believe what you like on that score.

[CloaknDagger]

It's all fluff... believe what you like on that score.

Yes, where is the ion engine fluff from?

[Daryk]

Just me... the thrust is very low and super-efficient compared to "regular" Battletech rockets... sounds like an "ion engine" to me.