Calculated and Predictable Part Degradation, Wear, and Failure (NO Randoms included)

[Blaster]

I've seen endless threads about part degradation, but they all fail on one rule: No Randoms. Well, this one is designed with no randoms. Do not play lawyers with words here, this is designed as a predictable system that does not have a single random. If implemented, identical launches should fly and fail in the same way.

Here's an example of how you can make part degradation predictable...

1: Active Parts

Active Parts are parts that move, thrust, spin, or do things other than sit and dispense resources.

Active Parts are the prime candidate for lifespan. The idea is simple. Lifespan is calculated by the time the part is in each environment biome, dependent on the biome (so, metal parts in a corrosive biome will degrade faster than in space, for example). Then, add more wear for using the part (like thrusting with an engine, reaction wheels spinning all the time, etc), and increase the wear when the part is overheated, by the amount of overheat it receives. Wear can also be increased by the amount of G-force received beyond its rated G-load.

Lifespan should be long, like 10-50 years, depending on part. Some parts won't last that long, but part failure due to age should only be a problem for ships that are constantly reused or are constantly overworked due to poor design. Single mission ships should not come across degradation problems unless the design is poor or the piloting is poor.

At 80 or 90 percent wear (whichever works best, just choose one threshold percent for the part), the part should experience degraded performance. A very worn engine can have its thrust halved, but still consume the same amount of fuel, reaction wheels could have their torque halved (halving performance when the wear crosses the near failure boundary is a relatively simple way to do it), antennas could take twice the power to transmit, solar panels could have half the power output and take twice as long to align, and so on.

At 100 percent wear, the part goes dead, and fails to operate at all. They can be repaired, though. A Kerbal can go EVA and kick the antenna to make it work again, or repair the part, which resets it back to 70 percent wear, or a wear percentage appropriate for the part. This encourages proper ship maintenance when doing reusable crafts far beyond their service life, and gives us another thing Kerbals are useful for in space.

2: Passive Parts

Passive Parts are structural parts or resource parts. They do nothing beyond dispense stored resources or provide structure. Wear works similar, but for different reasons.

A resource part could start leaking when it crosses the threshold of near-failure, at a rate porportional to the wear or at a fixed rate. A Kerbal should be sent out to fix it, partly to prevent losing all the fuel, and partly because at complete failure, the part will no longer crossfeed. Docking ports don't dock if completely broken, and structure only parts in completely broken state can fail their joints, either at a significantly lower than normal tolerance, or as a consequence of becoming completely broken. Either one would be a problem, though the second one might be too severe for most parts.

3: Extra thoughts

This example of predictable part wear and failure would be an interesting addition to KSP, and a challenge to players that reuse ships without recover/relaunch.

When economy is implemented, reusing ships will be a valuable strategy, so a system that allows recover/rebuild/relaunch without spending extra money essentially building a new ship every launch would be a great accompaniment to it, and would give the player a good choice dillema: Service and reuse an older ship to save on cost at the risk of failure, or build a new one for a lot more money?

[Sirrobert]

I have some questions on this:

Say you are on a 6 year mission to whatever planet, and your station back home has degraded to 0 (or atleast some parts). Would this result in the station falling apart, or just the parts becoming inert?

Could you send a rocket with spare parts up to your station, and replace whatever is old, or would you need a new station when the old one reaches its old age? Both would provide an interesting step. Plus it's always fun to deorbit a big station

Overall I think it's a very interesting idea

[Blaster]

Well, your station should last longer than 6 years, unless you had a problem putting it in orbit, then failed to maintain it. And note that part breakage does not mean explosive failure - that is part of the game already. The station will simply "go dead" and be adrift with no power or anything if you don't maintain it periodically and you time-warp for like 20 years or so.

As for joint breakage, it's probably best that the joint is easily broken if the structure part has degraded to 100 percent wear, with a damaged texture, and you just have to be careful docking, or for safety, send a Kerbal out to fix it before docking, instead of just gibbing.

And yes, another part of economy could be to have a spare parts bin that you need to restore parts to mostly repaired order, like say 90% of the initial wear, with the durability reduced so that the 10% wear is now 0% wear, but the part will wear down 10% faster. This is to prevent exploiting repair repair repairs to get true 0 percent, but still put an age limit (though greatly extended) on the parts. The key here is the time it takes for parts to wear down, which can be more rapid for certain parts, but others (such as structure supports) should have a very long life so long as they aren't abused (like centuries or millenia if its a lone fuselage floating in space).

It also would be very useful to have the Kerbal Alarm Clock Mod implemented in the game, so you can set maintenance reminders for these things.

Edited October 20, 2013 by Blaster

[Nuke]

i would have nothing against part wear and eventual failure if it was possible to repair them with an eva. however i would limit what kind of parts can degrade. id say engines (especially ion engines) anything with electronics (sas, gyros, sensors, antennas, etc), and tankage. and this would not be a catastrophic failure, it would be something you can go out and fix. if anything just to give evas more of a purpose. i see you getting paid to service/upgrade communication satellites and space telescopes, which would have wearable parts that need to be fixed.