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TT-38K Radial Decoupler

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TT-38K Radial Decoupler
Part image
Decoupler by
O.M.B. Demolition Enterprises
Cost (total) 600.00 Fund
Mass (total) 0.03 t
Drag 0.2
Max. Temp. 2000 K
Impact Tolerance 8 m/s
Research Stability.png Stability
Unlock cost 1200 Fund
Since version 0.7.3
Part configuration decouplerRadialTT-38K
Ejection momentum 2500 Ns
Testing environments
On the surface ✓ Yes
In the ocean ✓ Yes
On the launchpad ✓ Yes
In the atmosphere ✓ Yes
Sub orbital × No
In an orbit × No
On an escape × No
Docked × No
Test by staging ✓ Yes
Manually testable × No

The TT-38K Radial Decoupler is a decoupler that allows for staging rockets horizontally and in parallel.


The TT-38K adds a stage to the rocket and when activated will jettison the Decoupler as well as anything attached to it, much like the TR-18A. Visually, the decoupler's legs are left behind, but they add no mass or drag to parent part.

In the past liquid fuel system modules could not be attached to a TT-38K, however you could attach TT-38K's to solid fuel system modules. An easy workaround used by many was simply attaching a RT-10 Solid Fuel Booster to the TT-38K and then stacking liquid fuel system modules below.

Since version 0.13 however the stock liquid fuel systems have been radially attachable and either fuel engines below them, or through use of the FTX-2 External Fuel Duct fuel line, also introduced in this version.

You will often find that if you have a long section of liquid fuel tanks or solid boosters that they can twist the joint and potentially break off or explode on your craft. For this reason it is wise to use the decoupler towards one end of the side pod and use EAS-4 Strut Connectors to keep the other end steady, preferable a pair to help reduce the twisting the side pod might have. You should also consider using the decoupler towards the top of the side pod, so that jettison force helps push that end away from the ship, effectively peeling the side pods away.

Product description

The TT-38K Radial Decoupler, like most other decouplers, is equipped with a (hopefully) small explosive charge, that will sever the structural linkage between itself and whatever it's connected to.

Radial Symmetry

In game Symmetry Modifier

Unlike a stack decoupler, a radial decoupler can be combined with symmetry to an interesting effect. Using the symmetry feature found in the VAB, one can attach 2-8 symmetrical pieces onto their main fuel engine, to allow for more balance in precision in placing your initial booster stages. See example. Pieces however, whose collision mesh collide with one another will not stay onto their respective decoupler; this means you'll have to use fewer decouplers per stage, and more stages if you want more pieces.


  • New model and texture
  • (undocumented) Ejection Force increased from 5 to 120
  • Decouplers now obey the second law of physics (Acceleration = Force/Mass)
  • (unimplemented) Increased the ejection force of Decouplers and Radial Decouplers (too underpowered after the physics fix)
  • Removed parent-wise fuel cross-feed from Radial Decouplers. Fuel Lines made that obsolete
  • (undocumented) Ejection Force decreased from 15 to 5
  • (undocumented) Radial decouplers can now cross-feed fuel
  • Radial decouplers now have their own module (they used to share modules with the stack decoupler)
  • Tweaked the Radial Decoupler separation. It can now eject lit SRBs safely away from the ship and not kill the crew every time
  • Initial Release