Question about docking port strength

[Cashen]

Hey guys. Question for you. I want to do an interplanetary mission that delivers multiple probes to the Jool system. The idea is to have a core interplanetary stage and then docking ports attached radially and each probe docks to the core to hitch a ride. My concern however is, how strong are the docking ports? Would they snap off/undock under the stress of the interplanetary burn? Would is be better to align them up/down with relation to the direction of thrust?

Edited July 10, 2014 by Cashen

[ThePsuedoMonkey]

They'll be more stable if you line them up parallel to your engines, but that shouldn't be necessary if the probes are short and under a ton.

[annallia]

Depends on how heavy your probes are. Otherwise what you could do is use a bi/tri coupler with ports on each one and attach them to the ship that way.

You can also mitigate the stress put on the ports by throttling up slowly rather than jumping strait to full throttle. There is really little difference between full throttle and say half throttle on stress once you are up to speed but kicking it in to full throttle right off the bat tends to jerk the ships connected by the ports.

[Kyne]

Well, considering that you're going to be using the docking ports to carry probes and not to join pieces of a bigger ship together, you should be fine (as long as your probes are relatively small, and not entire multi-stage rockets in themselves ). Make sure your ship is balanced first, and if the probes start to wobble try the quantum struts mod to sort that out. You could always ditch the docking ports all together and radially attach separators and reinforce the probes to the hull with struts.

That's about it, I think. Happy flying!

[Cashen]

They'll be more stable if you line them up parallel to your engines, but that shouldn't be necessary if the probes are short and under a ton.

I had a feeling that would be the case. The probes are rather heavy. I think I'll attach some 1.25m tanks radially and have the docking ports on the top to align them with the engines.

[ThePsuedoMonkey]

Sounds like a good plan! I just did a test of 100 sepratrons pulling 10T through a single junior docking port with no problem, so that should work out fairly well so long as you don't have any balance issues.

[Scarecrow88]

What I have found when adding probes radially is that once you have detached one, it unbalances the remaining carrier craft making it difficult to control. For multiple probe delivery vehicles I prefer to stack them inline.

[shand]

I go 1 inline, and then in pairs as need be. First drop off - inline, second drop off - one radial and move the other radial to the inline position. third - inline. repeat until you run out of probes.

[Vanamonde]

Docking ports can be a little fragile under crushing forces, but sideways, they are quite strong. Example: delivering 8 rovers to Duna/Ike: They will sway a bit under thrust, but as long as you keep the acceleration under a G or so, you'll be fine.

[Cashen]

Docking ports can be a little fragile under crushing forces, but sideways, they are quite strong. Example: delivering 8 rovers to Duna/Ike: -snip- They will sway a bit under thrust, but as long as you keep the acceleration under a G or so, you'll be fine.

Interesting. I might have to experiment, since that's the opposite of what I expected.

As far as balancing, the probes will be attached with their own self-contained propulsion/RCS, so as one comes off, I will shuffle them around the core stage to keep it balanced. This is why I'd use docking ports instead of decouplers. That and I can assemble the thing in orbit instead of trying to build it all at once in the VAB.