What's the difference between stack Separators and Decouplers?

[Tex]

So I'm not exactly new to KSP, but there's been something that's always befuddled me: the title question.

I'd be your bestest friend if you could clear it up for me!

Edited March 4, 2014 by Maximus97

[Vanamonde]

Say you've got a ship consisting of part A (root part or close to it), connector C, and then part B. If the connector is a decoupler, firing it will produce two sub-assemblies, A and CB. If the connector is a separator, the result of firing will be 3 separate pieces, A, C, and B. To be honest, I've never understood the need for the separators to have been added to the game, but that's the deal: decouplers stick to one side or the other, while separators stick to neither.

[Dave Kerbin]

The decouplers only detach one end. So for example you place a decoupler between a fuel tank and your command pod with the arrow pointing toward the pod. When you stage the decoupler the fuel tank (with the decoupler still attached) will break away from the command pod.

Seperators detach both ends with the seperator left as a seperate piece. This is useful if you need to do things with both pieces. Seperators do weigh more though since they have 2 sets of explosive bolts.

[magnemoe]

You can mostly use decouplers, separators has two benefits they don't stay connected to any parts, this is nice if dropping an lander from an mothership.

You can not mess up direction, if you mount an decopler the wrong way by accident and put an engine over it the engine will not work. An common problem is mounting probes on the bottom of ships.

[Rickenbacker]

I use separators on top of docking ports, which leaves me with a clear docking port after decoupling. The disadvantage is the extra debris (the coupler ring), but sometimes it's worth it to f ex be able to dock to an almost spent booster and use the last of its fuel.

[Red Iron Crown]

Separators are more massive than the equivalent decoupler, so unless you need the double separation it's generally better to use decouplers.

[Geschosskopf]

Separators also fire with less net force than decouplers, probably due to having the same force going in both directions. Thus, they impart less velocity change to the parts involved, which is useful in some situations.

But the coolest thing about separators is their entertainment value. Most people use them for more delicate operations but their highest and best use is between the main stages of your lifter. When you stage and the engines of the upper stage fire, they blow the free-floating blue ring back into the spent booster at extremely high velocity. This results in a very gratifying explosion safely behind your ship involving nothing but debris you don't want to have anyway. Seriously, launches are MUCH more fun if the stages are punctuated with explosions .

[Space_Meerkat]

Short And Simple : Decouplers when fired will stay attached to the part of the craft that is being detached. Stack Separators Detach From Everything and don't stay connected to the rest of your craft. I prefer normal decouplers, Mainly because it leaves less Debris In LKO for me to de-orbit ( I know i can use the tracking station but i feel like that is cheating)

[Pecan]

I have a satellite placement vehicle intended to position 3 satellites, one at a time. The best (simplest, most aerodynamic) way to stick the satellites on the vehicle was to stack them on top of each other. Decouplers would end-up either fouling an engine on and 'upper' satellite or the instruments on the one beneath it, so I used separators instead. Using a decoupler for the last/lowest was better, since that stayed with the, now redundant, placement vehicle, has less mass and doesn't become debris.

[Tex]

Wow, thanks for the awesome and quick responses, guys! I think I got this now.

[HUG]

My game always says I attached decoupler the wrong way. I have no idea why that is as it sticks to the part I want it to stick after fire it. But when I fire the Vessel off the final engine, my camera angle change wobbeling a lot and SAS becomes disengaged. So I guess it has something to do with this message, but no idea how I could attach it without this happens. I use Ferram Mod and some others but I have a feeling like it could happen since I use this Mod?! Any Ideas, suggestions?

EDIT: Answered! It was a root-part issue. Decouplers always want to keep sticking on the root-part or at least its direction. With that in mind it was pretty easy to figure out which part should be the route-part at the end and which decoupler need to be flipped then.

Edited August 31, 2015 by HUG

[Kerbal2023]

Separators explode really strong, so they kick your sattelites out of their finetuned orbits.

Edit: Actually this might be a bug I have due to mods, not a question of what part I use.

Edited November 20, 2023 by Kerbal2023

[Kerbart]

On 3/4/2014 at 9:31 AM, Geschosskopf said:

Separators also fire with less net force than decouplers, probably due to having the same force going in both directions. Thus, they impart less velocity change to the parts involved, which is useful in some situations.

With a decoupler you have the same force going in both directions too. Newton's 3rd law prevents anything else from happening. Separators might be applying more force though.