XLjedi

Ducted Fans Underwater

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Took me longer than expected to test this... 

Unfortunately, I was disappointed to learn they don't work at all underwater as a proxy for a submarine propeller.

Ah well, guess I'm stuck with underwater jet engines for those career deepest dive achievements.

 

 

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2 minutes ago, XLjedi said:

Took me longer than expected to test this... 

Unfortunately, I was disappointed to learn they don't work at all underwater as a proxy for a submarine propeller.

Ah well, guess I'm stuck with underwater jet engines for those career deepest dive achievements.

 

 

Oh wait what? (Sounds of all my dreams of fan driven boats shattering)

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Just now, έķ νίĻĻάίή said:

Oh wait what? (Sounds of all my dreams of fan driven boats shattering)

I know right? 

Technically, you can do fan driven boats, they just have to be like airboats.  (insert sad face)

Edited by XLjedi

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1 minute ago, XLjedi said:

I know right?

It sucks! No wonder when I first tried it didn’t even move! I thought it was a power-weight ratio thing, but no.

Edited by έķ νίĻĻάίή

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It became obvious when I had a craft that could easily VTOL in the air direction, but once the fans submerged, all lift/pull force ceased.

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Are you sure? I tried this when rotors first came out, but before props (and thus before ducted fan blades) came out, and that worked. Did you try long enough?

I should really get around to testing if the prop/helo/fan blades work, but I know rotors and small normal aero surfaces work

 

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@KerikBalm  I would of course love for someone to prove me wrong... 

However, in my case, I created a very simple positive buoyancy sub with what I call a "dive engine" using 4 ducted fans.  I had tested the craft on the runway and when the lift vectors pointed to the sky, there was enough power for VTOL flight from a standstill.  My assumption at this point was:

Since my lift-to-weight ratio is greater than 1.0, I should be able to invert the blade lift vector to pull the craft down... and maybe have enough power to (at least somewhat) offset the positive buoyancy and pull the craft underwater.  What I found was, as I increased the downforce, the fans did in fact pull the craft down... but as soon as the ducted fan blades sank beneath the water, the craft popped-back up as if it suddenly lost all downforce. 

When I turned on the aerodynamics overlay, I noticed the thrust vectors for the ducted fans disappeared at the same time the craft popped back up.  If I kept the downforce power on, the craft just bobs up-n-down as the pulling force of the ducted fans just disappears once they are a meter below the water.

I am not able to see your screenshots on the link you posted, but will look with interest when I get home later tonight.  Do you actually have a functional submarine using ducted fan blades as propellers?

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The Breaking Ground props work in air only

https://bugs.kerbalspaceprogram.com/issues/23271

 

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Breaking Ground subject matter moved to the Breaking Ground subforum. 

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On 1/22/2020 at 7:07 PM, XLjedi said:

Ah well, guess I'm stuck with underwater jet engines for those career deepest dive achievements.

 

2 hours ago, XLjedi said:

@KerikBalm  I would of course love for someone to prove me wrong... 

However, in my case, I created a very simple positive buoyancy sub with what I call a "dive engine" using 4 ducted fans. 

I just tested. The ducted fan blades do not work in water.

However, the conventional aero surfaces do, thus you don't need jets, and can operate submarines on Eve.

You aren't stuck with underwater jet engines

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12 minutes ago, KerikBalm said:

 

I just tested. The ducted fan blades do not work in water.

However, the conventional aero surfaces do, thus you don't need jets, and can operate submarines on Eve.

You aren't stuck with underwater jet engines

I might tinker with it again... but hey, we just got a new 1.9 update with cyclic rotor control and I figured that would never happen, so maybe they will work underwater now?

 

 

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On 1/22/2020 at 7:13 PM, XLjedi said:

I know right? 

Technically, you can do fan driven boats, they just have to be like airboats.  (insert sad face)

You can indeed.

z2fK7Wu.png

 

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2 hours ago, purpleivan said:

You can indeed.

Nice, mine is a hovercraft...   well...  pseudo-hovercraft anyway.  Didn't need a rudder and overall behaves pretty much as intend

LCAC-18_Pufferfish.jpg

I may have to defer to you on plans to transport this one to Eve though.  LOL

Edited by XLjedi

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