Proper water boyancy

[Xd the great]

How on the earth does a fully fueled plane not sink into the water?

[AVaughan]

Jet fuel has a density of around 840 kg/m³.  (Water is 1000 kg/m³).  Provided the plane's structure is fairly light-weight, and/or there are some water tight compartments that are full of air, a fully fuelled plane can float.  (That said, most things float way too high in KSP).

[The Aziz]

Yeah I have no idea how could they float

[klgraham1013]

Some parts float which definitely shouldn't, but, as said above, a plane or rocket can float.

[Rocket In My Pocket]

8 hours ago, Xd the great said:

How on the earth does a fully fueled plane not sink into the water?

The same way a fully fueled metal boat doesn't sink into the water, by displacing it.

Edited December 22, 2018 by Rocket In My Pocket

[ZooNamedGames]

Landing on water. Unheard of! Especially never heard of any ‘Sully’. 

In all seriousness, passenger aircraft are designed and built to be able to float so that those onboard can evacuate, so kerbal planes being able to float is actually more realistic than not.

[JadeOfMaar]

11 hours ago, Xd the great said:

How on the earth does a fully fueled plane not sink into the water?

All parts in KSP have maximum buoyancy because there is no line in their configs to tell KSP otherwise. Just like everything can survive up to 400m below if you turn on part pressure limits.

The setting exists that you can give it to parts, but nobody has used either of these, not even in a mod afaik (except maybe RSS). This is very likely due to the oceans not being very important to Squad. It just works/is simply there and ready for use, but that's it.

[Rocket In My Pocket]

8 hours ago, JadeOfMaar said:

All parts in KSP have maximum buoyancy because there is no line in their configs to tell KSP otherwise. Just like everything can survive up to 400m below if you turn on part pressure limits.

The setting exists that you can give it to parts, but nobody has used either of these, not even in a mod afaik (except maybe RSS). This is very likely due to the oceans not being very important to Squad. It just works/is simply there and ready for use, but that's it.

I looked in to modding custom pressure values, but couldn't find a single thing in the .cfg files about it that would change anything in game.

Any idea how to do it? Ie. What would the line be to add in the .cfg file to change the default 400m setting?

I could definitely see a user-base for a community "part depth balance pass." Even if we just did a quick and easy rough derivative of some other stat like cost, or mass. As it is, the setting is completely useless and only serves to bar you from ever going deeper than 400m. Heck, I'd do it just so I could use it myself.

Edited December 23, 2018 by Rocket In My Pocket

[FleshJeb]

15 hours ago, AVaughan said:

Jet fuel has a density of around 840 kg/m³.  (Water is 1000 kg/m³).

Both of those numbers are MUCH higher in KSP. Also, the ocean density varies substantially per planet.

[JadeOfMaar]

2 hours ago, Rocket In My Pocket said:

I looked in to modding custom pressure values, but couldn't find a single thing in the .cfg files about it that would change anything in game.

Any idea how to do it? Ie. What would the line be to add in the .cfg file to change the default 400m setting?

I could definitely see a user-base for a community "part depth balance pass." Even if we just did a quick and easy rough derivative of some other stat like cost, or mass. As it is, the setting is completely useless and only serves to bar you from ever going deeper than 400m. Heck, I'd do it just so I could use it myself.

I'd like to see a community "part depth balance pass." This will make splashdowns so much more interesting, eh? And easier to use Ore tanks for ballast. And would make things such as Angel-125's submarine parts more useful. They feature upgrade-able pressure limits.

I'd rather it not be derived from cost and mass. Cost should be irrelevant. This seems like the kind of thing you have to look at from all angles and judge whether it could float. So pressurized things like tanks and cabins; whether it's a wing piece or otherwise have a very great blunt surface area; whether it's hollow and open-ended like a girder or the Mk1 hollow fuselage; whether it should be particularly dense for its size like a landing strut or engine.

So this is where you start. These are the undeclared keys and their default settings.

PART
{
	name = abc
	buoyancy = 1 // You'll see a great difference by dropping this to just 0.8 so be cautious.
	maxPressure = 4000 // in kPa. This means 40 atmospheres where Kerbin is 101.325 kPa
}

The pressure scale in Kerbin's sea is 1 atm per 10m I think. To find out how deep you can go in a given planet's ocean with a certain pressure limit, this is the formula (from OhioBob): [depth limit = maxPressure / (ocean density * surface gee * 9.81)]. The depth limit on Eve should hence be 239.9m assuming that all oceans have a liquid density of 1. (In GPP, this is not so. The oceans of its moons have lower densities.)

[AVaughan]

 

2 hours ago, JadeOfMaar said:

I'd like to see a community "part depth balance pass."

Some parts should float, some should sink.  (And my Earth raised intuition says that many that do float should float much lower in the water than they currently do).  

There is also the pressure crush limits.  Lots of solid structural type parts (no cavities or air pockets) should be immune to crush damage.