Difference between revisions of "Decoupler and separator"

Revision as of 05:34, 15 April 2014

Decouplers are parts that allow detachment of one vehicle section from another. A typical example is the Rockomax Brand Decoupler.

Mode of Operation

Decouplers remain attached to one section of the vehicle. On many models, the affinity can be determined by an arrow decal that faces away from the section on which the decoupler remains.

They do not provide liquid fuel crossfeed, and thus isolate fuel consumption within the respective sections.

Sequencing

All actions in the same stage as the decoupler are executed simultaneously, including those on the detached section, even if that section is isolated from all command modules by the decoupling event itself.

Application Notes

Care should be taken to ensure that jettisoned engines have finished burning before detachment, as there is the risk that they will collide with the rest of the rocket. Because the decoupler stays on the jettisoned stage it usually makes it imbalanced. As the decoupler is mounted on the side facing the rest of the rocket, this imbalanced stage then slowly rotates inward. Almost empty booster stages are also relatively light causing a higher acceleration and overtaking the rocket. Both effects cause jettisoned stages which are still running to crash into the rocket in most cases.

Types

The first unlocked type is the stackable decoupler. The first small decoupler is in the first research node and is mandatory for further developing of any part.

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.

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 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.

Explosive decoupling

A RT-10 Solid Fuel Booster

As decouplers and separators have to be developed first, it is not possible to have multiple stages at the first launches of Career Mode. However there is an art of staging by placing RT-10 Solid Fuel Boosters next to each other, either connected at the side or arranged vertically so the exhaust of the upper booster fires onto the lower (they don't have to be directly joined). The idea is to build up heat through contact and rocket exhaust to cause overheating resulting in an explosion, decoupling the segments below it approximately when desired, like normal staging.

KSP YouTuber Scott Manley exploited explosive decoupling for a technique he calls "rocket surgery" describing it as more an art form than a science. Using this he was able to go all the way to Minmus and return with only Start technology in his video "Kerbal Space Program - 0.22! Lets Do Science! Lots Of Science".

Although explosive decoupling is possible with other engines, the first decoupler is already in the first research node. The decouplers are the more flexible and reliable staging method and become available before other engines capable of explosive decoupling. So it is particularly useful in the start of the career mode in version 0.22 when there is no decoupler but the RT-10.

Decouplers

Image	Part	Radial size	Cost ()	Mass (t)	Max. Temp. (K)	Tolerance (m/s)	Tolerance (g)	Ejection impulse (kgF∙s)[Note 1]
	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