Moving Craft Through Structural Tubes

[JEF_300]

So I had an idea awhile ago to create mini-hangers on my station for Gemini capsules. The idea is that you basically have a tube the width of the back of the Gemini service module. When the Gemini docks, back of the tube is "sealed" by the back of the spacecraft itself. 

Images of Test

I tried this once before we had structural tubes using a decoupler to make the mouth of the hangar, but the capsule kept bouncing off an invisible wall in the middle of the decoupler. That's why I tested this version, which uses a 2.5 m structural tube, in hacked gravity on the runway. As you can see, it worked, perfectly in fact. 

However, once I put the hangar into orbit, the Gemini capsule just bounced off, refusing to go inside. Why did it work in hacked grav on the runway, but not in orbit?

I'm including a save file. In the save, there is a hangar and Gemini rendezvoused in orbit, and the testing stand on the runway, so you can try it out yourself.

The Save File

[Chel]

I'll test the save and try to find out why it's happening

[Mr. Peabody]

@Raptor9 posted about this a while ago. Hopefully this will be of help.

 

[JEF_300]

Thanks @The Dunatian, that thread does seem to be about the same issue. The conclusion that thread came to was that it was impossible, due to the natural limitations of the stock fairing system, which I would agree with... if I hadn't already successfully tested it. 

Actually, I've successfully tested it several times over the past day, and with some variations. I've launched a Gemini on the pad and docked it to the test hangar, so being launched as separate craft isn't an issue. I decoupled a nosecone off the front of the hangar, as I did on the version I launched, and I was still able to dock. I was about to test launching the hangar inside another fairing.

[OHara]

2 hours ago, JEF_300 said:

I've successfully tested it several times over the past day, and with some variations

If I understand you correctly, the fairing stays hollow in many situations, but not yet in the situation where you really want to use it.

I would also expect your idea to work fine.  I looked at your craft and see the problem-- the fairing in flight acts like it has a wall over its opening --but don't see any solution.  

You  could speed up the testing, maybe, with a useful mod linked below, that draws the colliders. You might have to rotate your view and practice to visualize the colliders, because the mesh is drawn with no hidden-line removal, but it shows the wall at the end of your fairing in orbit, so could be useful to show you just when that wall appears.  
(and if you find the solution, you can post on the thread where  @Raptor9 had a similar question, because you both will make good use of it.)

 

[JEF_300]

Thanks @OHara, the collider mod was really helpful. It appears that the fairing collider invisibly extends over the opening when the craft is re-loaded. It's perfectly fine for the whole launch, but when I rendezvous with it, it has to be re-loaded, and so when I try to dock I end up bouncing against the collider. 

Edit: I have found a solution that seems to be working. On my original design, I attached the fairing as close to the end of the structural tube as I could, for aesthetic reasons. When I edited the hanger to have the fairing attach in the middle of the tube, the fairing stopped closing over the opening on reloads. It seems that when the game redrew the collision vectors, it missed the tube. 

So I guess this is just a quirk of the game that you have to be aware of if you're building in this specific manner.

Edited October 25, 2018 by JEF_300

[OHara]

The bug-tracker has a self-registration system and is at 
https://bugs.kerbalspaceprogram.com/projects/ksp

The KSP-specific advice on making a helpful bug report (which is you is followed to various levels of incompleteness on the tracker) is at
https://forum.kerbalspaceprogram.com/index.php?/topic/83213-stock-support-bug-reporting-guide/

 

Edit: Congratulations on finding a way to make it work.

Edited October 25, 2018 by OHara

[Pecan]

On 10/25/2018 at 2:27 AM, JEF_300 said:

Thanks @The Dunatian, that thread does seem to be about the same issue. The conclusion that thread came to was that it was impossible, due to the natural limitations of the stock fairing system, which I would agree with... if I hadn't already successfully tested it. 

Actually, I've successfully tested it several times over the past day, and with some variations. I've launched a Gemini on the pad and docked it to the test hangar, so being launched as separate craft isn't an issue. I decoupled a nosecone off the front of the hangar, as I did on the version I launched, and I was still able to dock. I was about to test launching the hangar inside another fairing.

I'm new to this topic so  might be missing something.

"Open the bay doors HAL"
"I'm sorry Dave, I'm afraid I can't do that"

= Put a door in that you can normally keep closed (as Raptor9's "plug").  When a ship approaches the hanger you remove the plug and immediately park the approaching ship.  As long as you never go beyond the physics bubble the collider mesh shouldn't be recalculated, I'd have thought, or does it happen as soon as you change vessel?