I'm not satisfied with the way bionic arms and legs work. It seems extremely odd that someone with a bionic arm (or two bionic arms) can increase their strength value. A robotic arm can't get stronger unless you increase the power it uses and/or replace its contractive components.

Now a rationalisation of that was given to me along the lines of 'well it reflects their ability to control the arm better and punch harder'. Ignoring the fact that modern bionic arms are actually the reverse, being easier to over use them than under use them, it also creates a bizarre situation where someone at S60 automatically knows how to use a bionic arm perfectly, but someone at S50 with 2 more advances does not.

In my mind a bionic limb should have its own S value independent of the character. The character can still use their other arm with their normal strength unless they've lost both.

A small change is also that the limb in question adds +2 Armour to the location rather than TB (effectively subdermal armour implants from RT so can be stacked).

Bionic Arms also have two different 'qualities', strength and motor control. A guardsman may have a good quality strength and a poor quality dexterity, which reflects powerful pneumatic pistons to cause tremendous damage without the fine motor devices to manipulate objects.

So I'm replacing the bionic arm and leg with the following:

Bionic Arm

Gains +2 armour to limb. Counts as a natural weapon.

Poor Strength: S30+1D10

Poor Motor Control: 1/2 Ag for all fine motor skill tests as the arm only has a closed and open function. -10 to WS/BS tests using the arm.

Common Strength: 45+1D10

Common Motor Control: Suffer -10 to fine motor skill tests.

Good Strength: 60+1D10

Good Motor Control: Gain +10 to fine motor skill tests (including sleight of hand).

If the character possesses two bionic limbs they can no longer use their own SB for damage in melee (although they still use it to determine carrying capacity as the arms themselves don't really help). A character can wield two handed weapons with no problem as the arm can scale back its power output to match the organic one.

Bionic Leg

Gain +2 armour to limb. Counts as a natural weapon. Tests made to resist fatigue from Narrative Travelling will only accumulate a maximum of -10.

Use the same Strength quality as the arms above (you can kick opponents if you don't want to punch them).

Poor Motor Control: Halve Ag for movement and any fine balancing skill tests. Roll an Ag test after running to avoid falling over.

Common Motor Control: Suffer -10 to fine balancing skill tests.

Good Motor Control: Gain +10 to fine balancing skill tests and +20 to any jump tests attempted.

If a character possesses two bionic legs they add the legs' SB together to determine carrying capacity and don't suffer negatives to Toughness tests resist Fatigue for Narrative Travel.

For me anyway bionics can be just as individual and important as weapon types and should receive a little more attention, hence the above.

Hellebore

Most of the strength of a good blow actually comes from the core of your body. Try punching someone with just your arm, and you'll cause a bruise, only seriously injuring the target if you hit a weak point. Punch someone using your hips to put the full weight of your body behind it, and you're looking at a much more serious injury.

Ever split wood with an axe, or pound rice into mochi? Arm strength's contribution is puny compared to the force the rest of your body exerts. Given that, a slight increase in damage due to exceptional arm strength granted by a bionic arm isn't unreasonable, given the potential for a more reinforced extension of the body's weight as momentum.

If I wanted to complicate the rules further, I think I'd rather have poor bionics limit the strength modifier of the weapon - it doesn't matter how much of your body's momentum you can put behind a swing if the arm can't translate that force properly. A Good or Best quality bionic would probably function as-is, providing a slight bonus to damage as the 41st century technology puts the admittedly incredibly advanced capabilities of a biological arm to shame.

I think we can agree, however, that strength tests utilizing the arm only should be reflected by the quality of the bionic arm, not the size of the biceps on the owner's real arm. For something like handshakes or (possibly) intimidation tests, the arm's mechanical strength is really the only variable at work. Poor quality bionics, even on a 65 strength feral worlder, should reflect that quality by having a set strength, as per your house rules. Best quality bionics, even on a 20 strength Psyker, should reflect that technological and mechanical wonder with a handshake to end all handshakes.

Worth noticing is the fact that in most cases the bionic arm or leg is attached to real body of flesh, blood, tendons, cartilage and bone. Unless the body the limb is attached to is ready to bear the stress of the mechanically generated force of the bionic limb, the limb is useless.

Imagine a mechanic arm which could, when attached to fixed wall or crane, lift 2000 pounds. Now, if you take a normal human who previously could lift 100 pounds with one arm, attach the bionic limb to him and he tries to use it:

If he tries to lift 250 pounds and he'll sprain his chest muscles and dislocates his shoulder as the bionic arm bends. If he tries to lift 1000 pounds he'll rip the bionic arm right out of his body along with parts of his shoulder, chest and back...

So basically the strenght of your body should set a "cap" on the strenght of your bionic limb. The only way you can start to throw cars with bionics is to have a bionic exoskeleton or a whole-body job.

I always assumed that bionic limbs were attached and housed more or less to the frame of the person. Like attached and reinforced to the spine. I also figured that since these limbs pretty much simulate (at common quality at least ) a natural arm. IE there are pain receptors and various other things so you can feel someone brush up against you or know if a bullet grazed and possibly damaged your appendage. Further your hands would most likely have these things in abundance.

My question is... where does this thing get its power from? My best guess: From some sort of ATP bio-electricity exchange device in the limb itself. So basically the user of the limb can't be crushing diamonds, punching through walls or running tirelessly for miles because the electro-sensors in the arms and/or legs relay info to the brain that A: It'd damage the servos and structure of the limb thus causing simulated pain responses sent to the brain. B: The body can't supply the necessary energy requirements for sustained and extreme uses. So if you arm wrestle someone with a common bionic arm you'll 'feel' the tightness of his grip and pain if he grips really hard or you grip really hard. Also you will 'feel' tired in the parts of the arm that is under the most stress that requires more energy than your body can safely meet.

Now with Good or better quality the mechanism for ATP bio-electricity exchange might be better and the feeling receptor devices actually work faster than the original nerves in your arm which translates to higher strength and increased agility. But you can still 'feel' the pain and fatigue when the arm is under stress and risks using more energy than your body can safely produce.

But.... I figure the whole problem evaporates if the limb(s) has(have) an independent power supply (say a plasma pistol flask or basic las battery or something). Then as long as that power supply holds out, your limb (depending on its quality) would truly work independent of the miniscule amounts of energy your body could come up with and not need so many redundant pain receptors and stuff. So you could punch through walls, crush concrete in your hands or jump two stories high (*cue the 6 million dollar man sound effects*).

So... Skipping the TL;DR I say its a good idea but I'd require it to take a power supply of some sort.

Edit: Because I don't want to seem like I'm poo pooing. With the power supply idea you could work all sorts of different and unique things your bionic limbs could do. And to do them all you'd need to do is expend a certain amount of charges per use or something like that. Imagine how cool it'd be to see someone pop some sort of energy clip into their arm and have it light up like a Christmas tree right before they punch through a wall.

Yui 56 said:

It doesn't work like that. The spine of a person is far too flexible and soft to handle the stress. Actually, the spine is far too flexible and soft to handle the stress of normal human weight standing up if the back and abdominal muscles were not supporting it. In real life tens of millions of people have back pains because their abdominal and/or back muscles are out of shape and their body weight is slowly damaging their spine. Plug a forklifter-strenght bionics into spine and all you get is permanent spinal injury along with two or four limb paralysis.

Actually the *only* thing keeping human body together at all is muscles and cartilage. Remove them and human is just a badly organized mess of bones and internal organs in a huge sack of skin. There is nothing solid to plug steel on except the muscles and they are just as solid as you work them out to be.

The only way to make a bionic limb considerably stronger than is natural for the persons own muscles is to plug it all into exoskeleton (like Space Marines do) or do a full-body conversion (Necron-style).

It depends how the arm is motivated. A bicep replaced with a piston attached to the humerus equivalent and radius equivalent doesn't require any other attachments and could thus push the forearm forward at a higher speed than the normal muscle. Synthetic muscles used contractial plastics could perform even better.

I agree that a synthetic muscle attached to the bionic arm AND natural body would cause problems if it's too strong, but it doesn't have to be. The grip of the hand is not governed by shoulder attachments and so you could easily produce an extremely strong hand that could crush a person's skull by gripping.

Hellebore

I'm not saying a bionic arm can't be a powerfull weapon. I'm saying there is a limit to it and the limit is more human physical one than technical one. Equip a normal human with a simple punch-dagger with good, solid-steel hand-guard and ask him to punch things. In few tries he will put the dagger through 3 inches of concrete. Ask a normal human to punch his hand into concrete and he simply won't do it.

Having a metal hand which doesn't break up and hurt you like a ***** will make pretty much anyone dangerous opponent in melee. If the hand can crush metal just by closing around it is a nice bonus, but not even needed.