Radical Jump Jets

Jump jets are crazy. I get that they throw 100 tons of battlemech 30 meters by plugging 2 tons of pressure chamber and controls into a fusion engine. 2 tons is a lot. Fusion engines are stronk. 

I also resent the slightly uneven specs of them. I don't expect a thrust:weight formula. But I feel like there's room for a 1.5 ton jump jet.

Anyway, here's the pitch:

Radical Jump Jets

An integrated system which uses turbines in addition to superheated air to thrust battlemechs efficiently across a battlefield.

Construction

RJJ's provide approximately 900 jump-meters of thrust per half ton. That's about 1 hex of Jump MP for a 30-ton 'mech per half ton. 

To calculate the jumping MP of a 'mech with RJJ, multiply the tonnage of its RJJ system by 60, then divide by the 'mech's tonnage and round down.

RJJ system takes up one crit per ton or fraction of a ton that it weighs. RJJ crits can be distributed across any of a 'mech's torso locations, but may not be mounted in the legs, arms, or head. 

RJJ require the 'mech mounting them carry a fusion engine. 

RJJ cost twice as much as a comparable set of conventional jump jets.

Calculating JMP

As with conventional jump jets, a 'mech's JMP from RJJ may not exceed its WMP.

A 'mech with a supercharger may use their supercharger to raise their JMP to their RMP (provided they have the tonnage of RJJ to allow that). This counts as a usage of the supercharger.

Restrictions

RJJ do not work in vacuum or thin atmospheres and they cannot be modified to work in the same.

When a 'mech uses RJJ in environments with precipitation or sandstorms, the user makes a determining critical hits roll with a -2 modifier. Any critical hits rolled are randomly applied to a RJJ or engine crit.

Optional Rules

Fractional Accounting: Under fractional accounting, take the 'mech's desired JMP, multiply by the 'mech's tonnage, and then divide by 60 to determine the tonnage of its RJJ system.

Margin of Success: Under margin of success rules, any attacks which exceed the target number to-hit and hit a location with RJJ can make a determining critical hits roll with a -2 modifier. Any critical hits are randomly applied to a RJJ or engine critical space in that location.

Discussion

30- and 60-ton 'mechs will probably find conventional JJ to be safer and more efficient than RJJ. The tonnage is the same. The 30-tonners might save some crits, but crits aren't usually that tight on lights anyway.

Weight efficiency peaks from 20-25 tons. It's crap for 35-55 tons. Worse from 65-85 tons. Then it's very gravy for everything at 90+ tons.

That said, the crits system are going to be tight on a typical assault. An Atlas that wants to fly with screaming turbines on its back will pay some 5 tons for the privilege and pay 5 crits. That's opposed to the 6 tons and 3 crits it would usually sink. Plus the weather and versatility restrictions.

I could tweak that 60 divisor up to increase efficiency a bit. That also dials down crits though. I like the idea of this as a crit-intensive system. I don't want to make XL jump jets, but until C-Bill cost becomes relevant, we've only go so many knobs to turn on this. 

I could leave the tonnage/crits as-is and give another gameplay advantage. Additional jump stability? Ability to jump out of water? 'Turbine mode' to act as weak UMUs? What if they could gather water and superheat that? That's so much more dangerous, but a steam-powered 'mecha-rocket is a fun concept. Water purity would be an issue.

I noticed few things hover in Battletech. The ability to hover for one turn would be interesting but I feel...that's a bit much. 

I don't know. I like the turbine mode. Letting it act as a very weak UMU. Half JMP as underwater movement MP (rounded down, minimum 1).