Air intakes shouldn't provide air when submerged

[Snark]

Just had some fun building my first seaplane in 1.0.5, I love what they've done with the water, for the most part. The ocean is actually an interesting place now.

However, I noticed that air intakes for jet engines work just fine regardless of whether they're in or out of the water. That's physically counterintuitive enough (for me, anyway) that it's pretty immersion-breaking (no pun intended). I like that we can build seaplanes, I like that there are some challenges in designing a craft that can take off again once it has landed in the water. But I would really like part of that design challenge to be: "...and you need to keep your intakes out of the water so you don't drown your engine."

I assume that this was just a simple outcome of the basic modeling in KSP (i.e. "intakes provide air if you're at an altitude where air happens"), rather than a deliberate design choice. I have no idea how complicated it would be to code things to include a position check on intakes so that they stop providing air when immersed. But if they've added enough hydrodynamics to apply drag cubes to individual parts when they're in the water, it seems to me that that gives them most of what they'd need to add such a feature.

So I'd really like to see something like that. Thoughts?

[sal_vager]

This is intended as there's no water engines, though if any are added later this behavior can be changed.

[Capt Snuggler]

Just had some fun building my first seaplane in 1.0.5, I love what they've done with the water, for the most part. The ocean is actually an interesting place now.

However, I noticed that air intakes for jet engines work just fine regardless of whether they're in or out of the water. That's physically counterintuitive enough (for me, anyway) that it's pretty immersion-breaking (no pun intended). I like that we can build seaplanes, I like that there are some challenges in designing a craft that can take off again once it has landed in the water. But I would really like part of that design challenge to be: "...and you need to keep your intakes out of the water so you don't drown your engine."

I assume that this was just a simple outcome of the basic modeling in KSP (i.e. "intakes provide air if you're at an altitude where air happens"), rather than a deliberate design choice. I have no idea how complicated it would be to code things to include a position check on intakes so that they stop providing air when immersed. But if they've added enough hydrodynamics to apply drag cubes to individual parts when they're in the water, it seems to me that that gives them most of what they'd need to add such a feature.

So I'd really like to see something like that. Thoughts?

I agree. air breathing engines should not work underwater, obviously!

An electric propeller should be provided to allow underwater propulsion. the electric propeller should primarily be for atmospheric flight, but still work reasonably well under water. kill two birds with one part so to speak.

[Claw]

There's actually already a flag in the .cfg to disable them underwater. So the game is set up, but as indicated, there aren't any replacement engines in game yet.

Cheers,

~Claw

[pandaman]

Initially I thought it wrong that jets work normally underwater (which it is, obviously). But, as Sal said, it makes sense for now from a game play perspective given that no alternative exists. Not perfect, but a good call IMO.

One day we will have appropriate underwater propulsion, then everyone will complain that the game is broken because jets don't work anymore

[Snark]

Except that the "S" in KSP doesn't stand for "submarine."

They just made a physics change to water that is a Good Thing. It happens to enable submarines, as far as the physics is concerned. It also happens to make water a much more interesting place, that you can interact with in expected ways when you're flying yourrockets and planes.

To me, KSP is all about providing interesting design challenges for flying stuff. That should take the front seat. Heck, they can always add a water engine in a future update, and I'll happily hold their hat and cheer them on.

I just want planes and rockets to work right. Do that first, worry about submarines later.

If I understand Claw's comment correctly: does that mean I can just write a snippet of ModuleManager config and get the intakes to work the way they're supposed to? Great, problem solved for me. I'll go look into it.

[NathanKell]

You understood correctly. Add disableUnderwater = True to all intake and jet MODULEs

[Capt Snuggler]

Heck, they can always add a water engine in a future update, and I'll happily hold their hat and cheer them on.

But then all my jet powered submarine craft that I have laboured over will be broken by that update! /sarcasm

[T-Bouw]

Props to you then!

[Snark]

You understood correctly. Add disableUnderwater = True to all intake and jet MODULEs

Excellent, that's exactly what I'll need, thank you! I'll go try it out as soon as I have a chance. I expect I'll leave jet engines enabled underwater and only disable the intakes. I don't have so much of a problem with underwater jets, as long as they get their air from somewhere-- an "air intake" sucking water was just too much for me. I'm fine with an underwater jet-powered craft that has a snorkel.

On another note: is there some way to find out (either directly from the game, or documented somewhere) a comprehensive, authoritative list of every flag that can be used in the .cfg files? I never would have discovered the "disableUnderwater" flag on my own, if you hadn't posted it here (because it's not present as "= false" in the current .cfg files, it's simply not there).

Normally I turn to the KSP wiki .cfg documentation (and module documentation) for help on this, but it's not comprehensive and always lags behind (often for many weeks) when there's an update. (For example, the ModuleResourceIntake wiki mentions nothing of "disableUnderwater").

Edited November 11, 2015 by Snark

[Claw]

They just made a physics change to water that is a Good Thing. It happens to enable submarines, as far as the physics is concerned. It also happens to make water a much more interesting place, that you can interact with in expected ways when you're flying yourrockets and planes.

Yep, that's exactly it. Buoyancy was updated, and that happen to allow this sort of activity. Since everyone knows that KSP players tend to be fairly industrious with what's available, the underwater environment was updated a little. However, as you said, it's not a boating/submarine game. I'd be surprised if there was ever a "water only" engine, but I can imagine them possibly adding an electric engine (prop?) that would also double as an aircraft propeller for solar type planes. Though I suppose that's getting off your topic.

Cheers,

~Claw

[Snark]

Just to provide some closure on the thread, for anyone interested in disabling intakes underwater: I followed NathanKell's excellent advice, and came up with the following ModuleManager snippet that disables all jet intakes when they're underwater:

// Disable all jet intakes if they're underwater.
// (It's possible to disable jet engines the same way, but I figure that's
// OK as long as they have intakes that are out of the water.)
@PART
[*]:HAS[@MODULE[ModuleResourceIntake]]
{
    @description ^= :^(.+)$:$0 Does not work underwater.:
    @MODULE[ModuleResourceIntake]
    {
        %disableUnderwater = true
    }
}

To use, just add a .cfg file anywhere in your GameData folder, and paste the above into it. (And you need ModuleManager installed, but if you have any mods at all you almost certainly have it already.)

I tested it with a simple airplane that has a bottom-mounted jet engine and a top-mounted intake, and it works exactly as I hoped: it's just fine as long as the intake is out of the water, but as soon as I roll the aircraft over to submerge the intake, the engine flames out. Perfect!

[NathanKell]

In particular, it checks the intake transform for intakes, and it checks that all engine transforms are above water, for engines.

[Captain Vlad]

Initially I thought it wrong that jets work normally underwater (which it is, obviously). But, as Sal said, it makes sense for now from a game play perspective given that no alternative exists. Not perfect, but a good call IMO.

Agreed that this was a very good call, and I haven't even built a sub yet. In my head the air intakes are water intakes for MHD-style engines anyway...I don't need no steenking water engine when my brain can come up with a way to explain it.

That said, if they did add an electric propeller (or multiple sizes thereof...), I'd be tickled pink, as that would be great for little planes on planets with an atmosphere but no oxygen for jets.