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I cant sink my submarine.


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Hello, I am trying to make a submarine to put on Laythe to get a thorough examination of its liquid, (i don't know what it is don't spoil it) but I can't get the submarine to sink for the life of me, I have 8 closed cargo bays, 16 ore tanks full of ore and 6 vector engines and it floats better than a life vest. 

RD9kJV5.png

Edited by Vanadiumn
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Posted (edited)

KSP parts are really buoyant. You need to reduce the volume and/or add even more ballast.

To give you an idea of the ballast/volume ratios, here’s a neutrally buoyant sub that doesn’t make use of cargo bays or similar tricks. It has 4 radial ore tanks as ballast, and it is really tiny compared to yours:

gM66Cj7.jpg

Personally I don’t feel bad about working around the lack of dedicated ballast parts and the general buoyancy problem when designing subs by exploiting some of KSP’s physics quirks. For example, you can clip 6 radial ore tanks inside a Mk1 cargo bay, to make one really dense ballast element. When you open the doors, it’ll become more buoyant because the volume of the ore tanks will be added to the craft’s volume.

Whichever way you do it, for a sub that size you need way, way more ballast than you’re using. This of course makes subs very heavy, so if you want to get it to Laythe without cheating, you’ll need a huge rocket — or a way to fill those ballast tanks in-situ by drilling, which is an interesting design challenge in its own right.

 

Edited by Brikoleur
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7 hours ago, Brikoleur said:

KSP parts are really buoyant. You need to reduce the volume and/or add even more ballast.

To give you an idea of the ballast/volume ratios, here’s a neutrally buoyant sub that doesn’t make use of cargo bays or similar tricks. It has 4 radial ore tanks as ballast, and it is really tiny compared to yours:

gM66Cj7.jpg

Personally I don’t feel bad about working around the lack of dedicated ballast parts and the general buoyancy problem when designing subs by exploiting some of KSP’s physics quirks. For example, you can clip 6 radial ore tanks inside a Mk1 cargo bay, to make one really dense ballast element. When you open the doors, it’ll become more buoyant because the volume of the ore tanks will be added to the craft’s volume.

Whichever way you do it, for a sub that size you need way, way more ballast than you’re using. This of course makes subs very heavy, so if you want to get it to Laythe without cheating, you’ll need a huge rocket — or a way to fill those ballast tanks in-situ by drilling, which is an interesting design challenge in its own right.

 

Are there certain parts that have more ballast than others? and which parts have buoyancy and which parts don't? 

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Nevermind, my booty just slammed into the ocean floor going 20 m/s .

R2EICUS.png

 


All i had to do was triple the amount of service bays and put mk1 fuel fuselages in all of those service bays and close them. but now I don't know how propellers work.. or steering..

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You’ll figure it out. Rudder in the back, elevators in the front, ballast positioned so  that it floats level. Go with ever so slightly buoyant, then use the elevators and your forward motion to dive.

Use jets for propulsion to start with. Marine propellers are possible but the stock propeller blades don’t work underwater so it’s a lot of work to find a solution that does.

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2 hours ago, Brikoleur said:

You’ll figure it out. Rudder in the back, elevators in the front, ballast positioned so  that it floats level. Go with ever so slightly buoyant, then use the elevators and your forward motion to dive.

Use jets for propulsion to start with. Marine propellers are possible but the stock propeller blades don’t work underwater so it’s a lot of work to find a solution that does.

Alright, thank you

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@Vanadiumn I can give you a config file and resources config file to make a new part ballast tank out of stock  KSP foil Baguette fuel tank if you like.

It works in 1.9.1 and 1.10.1 Unless there is a major change in the folder structure or mesh names in 1.11.1 it should work in it as well.

I am creating parts and posting my progress in.

https://forum.kerbalspaceprogram.com/index.php?/topic/201673-working-underwater/

 

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11 hours ago, ColdJ said:

@Vanadiumn I can give you a config file and resources config file to make a new part ballast tank out of stock  KSP foil Baguette fuel tank if you like.

It works in 1.9.1 and 1.10.1 Unless there is a major change in the folder structure or mesh names in 1.11.1 it should work in it as well.

I am creating parts and posting my progress in.

https://forum.kerbalspaceprogram.com/index.php?/topic/201673-working-underwater/

 

I'd like that, thank you.

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On 5/3/2021 at 10:47 AM, Brikoleur said:

You’ll figure it out. Rudder in the back, elevators in the front, ballast positioned so  that it floats level. Go with ever so slightly buoyant, then use the elevators and your forward motion to dive.

Use jets for propulsion to start with. Marine propellers are possible but the stock propeller blades don’t work underwater so it’s a lot of work to find a solution that does.

I cant steer the submarine even with the rudder and the elevators, I can move in one direction, and it's forward.

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4 hours ago, Vanadiumn said:

I cant steer the submarine even with the rudder and the elevators, I can move in one direction, and it's forward.

Can you post a picture, or even better, the craft file e.g. at kerbalx.com?

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fI6Qimp.jpgThere are not any control surfaces acting as elevators.  The ones on the top can only turn on their horizontal hinges, so they don't deflect the water flow to make any steering.  You need elevators placed like the fins on a whale's tail, or the like the front fins of a fish.

The 'remote guidance unit' on the back is rear-facing, so rudder-steering will be backwards.  The rudders might be fighting the reaction wheels, causing no steering overall.   You can turn the 'remote guidance unit' forwards, or use its 'ControlPoint: Reversed' option to make the rudders steer properly.  

The propeller blades from the Breaking Ground mod do not work under water, unfortunately.  They do not push against water, only air.  The stock aerodynamic surfaces do work, although a propeller built using the smallest elevons will be larger than what you have.

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Posted (edited)
56 minutes ago, Vanadiumn said:

Here!

Your steering problem has two causes:

  1. Your control point faces backwards. This means all of your control inputs will be reversed.
  2. You have neither a rudder nor elevators. 

You have two control surfaces at the bow, but the rudder needs to be at the stern. You have a vertical wing element in the right spot. Stick an elevon on it and it will work as a rudder.

Your elevators need to be near the nose, and they need to be horizontal. The control surfaces you have along the back won't do anything (much).

There are a bunch of other problems with it too, however.

  1. It's still much too buoyant. You need much, much, MUCH more ballast to make that beast sink. The small radial tanks you're using barely even register. I added 282 tons of ore (without abusing cargo bays), for a launch weight of 444 tons, which was sufficient for it to sink... just. Remember also that it'll become more buoyant as you burn off fuel. (You can cut down the ballast requirement massively if you put the tanks inside cargo bays. You said earlier you were able to get it to sink with the Mk1 fuselages inside the 2.5 m bays, but it doesn't do it for me, thing floats great.)
  2. The propeller on the rudder does nothing apart from introducing some drag. Stock propellers don't work underwater. If you want a prop-driven sub, you need to make your own from elevons.
Edited by Brikoleur
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I switched out the back propellers for elevons and added some fish-like fins made of elevons on the front of the submarine, I can turn but it really wants to drift right and i need to go flat on my side to turn it, besides that, I can turn now. I'm gonna start working on the ballast.

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11 hours ago, Vanadiumn said:

I switched out the back propellers for elevons and added some fish-like fins made of elevons on the front of the submarine, I can turn but it really wants to drift right and i need to go flat on my side to turn it, besides that, I can turn now. I'm gonna start working on the ballast.

You might want to try a rebuild. I think some of the parts that are supposed to be symmetrical, aren't. That would explain the drift.

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Okay, I added a good ballast and more elevons, it sinks and i have good control of pitch, yaw, and roll.  I have a good submarine! Thank you for the help. 

One last question, is there any scientific equipment that tells you anything about Liquid? 

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