Heh First off Battletech dose have an energy shield of sorts, it's called
Blue shield It's current iteration only works effectively for 60 seconds at a time (six B-tech turns, the turns do not have to be consecutive) and only works on particle cannon hits (50% less damage), the systems capacitors can go boom if hit while it's active. It's also expensive and a maintenance nightmare. Not surprisingly it's not very common.
Battletech also has physical shields, These absorb a specific amount of damage from an attack but slowly take damage as well, which eventually renders them useless, larger shields last longer and can absorb more damage but they also reduce the mechs movement profile (not to mention they block weapons fire from the torsos while in use).
So their not very popular out side of Solaris, the only real production models that have them is the House Davion Valiant light battlemech (but the base model dose not have it).
In any case none of these items are available until after the clan invasion.
A few things to note about battletech
Battletech vehicles are much faster than they first seem.
A 3/5 battlemech can move at 54 kph (33.55 mph), this in battletech is a slow mech (many assault mechs are this fast) however looking at real life vehicles a M1 Abrams has a stated off road ability of just 48 kph (30 mph) and yes it dose have the trick of able to disable it's engine governor... (at which it has a top speed of around 70 mph (112 kph) on
smooth roads, but it's not recommended to do this for the tank or it's crew). So in short a 100 ton Atlas mech has the same off road ability as a 65 ton M1 Abrams tank of today (most current MBTs have smiler off road ability's).
Also note all Tracked, wheeled and hover based ground vehicles gain a +1 movement to their over all movement capability when on roads, so a 3/5 tank can move 6 hexes a turn when on roads (or 64.8 kph or 40.27 mph, which is not to far off from an Abrams governed road speed of 42 MPH (67.2 kph)).
Further more theirs a number of options that increase the speed of the unit that do not involve out fitting the unit with extra gear, these navigation Satellite up-links (+1 movement, due to better maps), a rule that allows a unit to "sprint (or overdrive for vehicles, this has the effect of MASC or 2x walking speed, it also stacks with MASC and the experimental supercharger (which is oddly partly fluffed as a disabled governor))" and a pilot ability (from the RPG) that allows for a +2 movement while "sprinting".
Using all three of these ability's a 3/5 mech can reach a top speed of 97.2 kph (60.4 mph). Though the down side of using these ability's is the unit is concentrating on moving at this speed, as such it's not taking evasive action, and thus easier to hit and is not able to fire back as well.
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Battletech armor is strong but the rules have it a bit contradictory about it, for example a Gauss Rifle fires a 125 kilogram slug (275 pound, about the size of a eight inch naval shell) at hypersonic velocity's (tech manual and a few others mention incredible velocity's, TRO 2750 and the older BMR said twice the velocity of conventional shells, and the majority of novel quotes indicate hypersonic (1,700m/s or faster) velocity's). At say 1,920m/s the Gauss slug has a kinetic energy of 230 megajoules To put that into perspective the 120mm gun on the M1A2 Abrams tank fires a Ke projectile that only deals 8.5 megajoules. And the 16 inch AP shells from an Iowa class battleship at 25,000 yards only deals ~150 megajoules (even at 1,700m/s the Gauss slug is still doing 180 megajoules). And battlemechs can take a number of these hits and survive.
Why 1,920m/s, well the Heavy Gauss Rifle slugs are also stated to be hypersonic (see the novel End Game for that), if the Heavy has a velocity of 1,750m/s and we scale the resulting KE with the damage of the regular Gauss it has to have a velocity of ~1,920m/s.
Though the interesting thing on battletech armor is that it seems to fail quite easily when we have a high mass and low velocity impact, like melee attacks, ramming or falling down... A battlemech that gets rammed by another battlemech can easily have it's armor damaged by one or two megajoules, strangely the charging mech only takes a tenth the damage... Though oddly Aerospace fighters can survive impacts at 3km/s velocity's with some armor intact.
In sort battletech armor seems to do well on low mass high velocity impacts but less on high mass low velocity impacts, it also seems to do less well on mass impacts, like a burst of autocannon fire.
Edited by nebfer, 03 November 2011 - 10:44 AM.