Decoupler and separator

Decouplers are parts that separate stages of craft either vertically or radially. They don't transfer of liquid fuel and oxidizer automatically, preventing that the upper stages are drained first. All commands in the same stage as the decoupling are executed too, even when they are on then detached stages without a command module or above the decouple command (but in the same stage!).

Types

Decouplers, like the Rockomax Brand Decoupler, remain attached to one side of the rocket. That direction can be determined by a small arrow facing away from the side it stays attached to. Separators, such as the TR-XL Stack Separator are a special type of vertical decouplers, which separate from both sides, leaving three crafts: Both sides of the separator and the separator itself. Separators mass slightly more than the similarly sized decouplers. Each one separator and one decoupler cost more than their same sized counterparts. The tiny sized decoupler and separator cost the same.

The symmetry modifier in the VAB

Radial decouplers, such as the TT-70 Radial Decoupler, attach to the sides of a rocket and eject stages horizontally. This can be useful for setting up asparagus staging, among other uses. As the ejection force may not be enough to avoid collision afterwards Sepratron I can be used to push detached stages away. Those decouplers also allow the usage of the symmetry modifier of the VAB combined with adding booster stages. Particular care must be taken to ensure that jettisoned engines have finished burning before, as there is the risk that they will collide with the rest of the rocket as they continue to accelerate.

The TT18-A Launch Stability Enhancer can also be classified as a decoupler, although one side is fixed to the ground. But the sound effects are similar and they share the same functionality, separating two parts. It was also be officially defined as a decoupler, but was changed into strut.

Decouplers

Image	Part	Radial size	Cost ()	Mass (t)	Max. Temp. (K)	Tolerance (m/s)	Tolerance (g)	Ejection impulse (kgF∙s)
	TT-38K Radial Decoupler	Radial mounted	600	0.025	2 000	8	50	250
	TT-70 Radial Decoupler	Radial mounted	700	0.05	2 000	8	50	260
	Hydraulic Detachment Manifold	Radial mounted	770	0.4	2 000	8	50	450
	TD-06 Decoupler	Tiny	150	0.01	2 000	6	150	50
	TD-12 Decoupler	Small	200	0.04	2 000	6	150	100
	TD-25 Decoupler	Large	300	0.16	2 000	6	150	150
	TD-37 Decoupler	Extra large	375	0.36	2 000	6	150	200
	TS-06 Stack Separator	Tiny	215	0.01	2 000	6	150	50
	TS-12 Stack Separator	Small	275	0.05	2 000	6	150	100
	TS-25 Stack Separator	Large	400	0.21	2 000	6	150	150
	TS-37 Stack Separator	Extra large	500	0.48	2 000	6	150	200