Some rules I have been coming up with myself for AirMech-only mode, modifying the rules in Interstellar Operations. I call them StrikeMechs because they are more about speed and hitting hard and are essentially unstable flying cannons:
Weighing up to 75 tons
Limited to bipedal Mechs
Minimum Jumping MP = 3
No Conversion Equipment necessary
No Landing Gear Critical Slots
Avionics Critical Slots in Head, LT, RT
A critical hit on any Avionics section reduces Cruise MP by half.
A second critical hit on Avionics, or the loss of either side torso, causes the loss of ALL Cruise MP.
Prohibited Technologies: same as LAM except those relating to additional critical slots (the lack of conversion equipment means that criticals can be spread around), or restrictions on engine types. Also, StrikeMechs may NOT mount Bomb Bays (but may carry bombs in their hands).
Treated as a LAM in Airmech mode for most rules.
Uses all AirMech Mode movement rules (including dual-Piloting skill requirements depending on whether or not it is in the air or the ground).
StrikeMech Cruise MP = lesser of Walking MP x 3 (x 2 if over 55 tons) or Jumping MP x 3 (x 2 if over 55 tons)
StrikeMech Flank MP = Cruise MP x 1.5 (round up)
StrikeMech Walk MP = Walking MP / 3 (round up)
StrikeMech Run MP = Walking MP x 1.5
Heat: Walk or Run MP = 1 / MP used
Heat: Cruise or Flank MP = 1 / 3 MP used - 3 Heat (to a minimum of 0) to account for the additional heat venting allowed by the design.
(Example: An StrikeMech which cruises for 19 MP generates (19/3 - 3) = 3 Heat)
Side-slipping, Skidding, Collisions, Unintentional Charging and Crashing are all the same rules as LAM Air-Mechs.
Transporting StrikeMechs requires a standard Mech bay. Unlike LAMs, they cannot be loaded into Aerospace Fighter bays.
The manufacturing cost premium for a StrikeMech are at 10% of chassis costs (i.e. excluding weapons, ammo, and equipment) due to the specialized nature of the design.
If this seems a bit much, I should point out their GREATEST ENEMY is THEMSELVES. These things are one failed piloting check from serious damage or destruction.
If a 20 ton Stinger-S, moving at 15 hexes per turn, would take 30 points of damage from running into something. (Which would pretty much destroy it.)
A 55 ton Shadow Hawk-S, falling 3 elevation levels, would take 24 points of damage, enough to blow through most of its armor in any location.
The 75 ton Thanatos-S, performing an 'AirMech Ram' attack at Cruise speed would deal 120 damage to whatever it hit, but would suffer 60 to its own center torso (almost destroying it). This assumes the pilot made the willpower check (11+) to attempt the maneuver.
