Adapter

An adapter is a part which allows to place multiple stacks of parts beside a single stack. Although some adapters have “coupler” in their name they don't work as decouplers and are statically attached. Beyond the common structural parts, many fuel tanks can be used as adapter too.

Attributes

All of these parts are Fuel Crossfeed Capable, meaning that when there is a fuel tank on the single side and an engine on the multiple side of the adapter, propellants, like liquid fuel and oxidizer, will flow through the adapter on the way to the engine. However, it should be noted that fuel will only flow from the single end to the multiple ends, and not vice versa; this prohibits use of an upside-down adapter to supply fuel to a single engine from multiple stacks.

The branches are unsupported and prone to bending or breaking if the weight and thrust are not properly distributed. Rockets incorporating an adapter are also likely to wobble, unless the stacks are opportunely bound together with struts.

Uses

The main uses of these adapters include connecting a small payload, such as a space probe, to a large launcher, or using several small engines on the bottom of a large fuel tank to increase efficiency. If a one-to-multiple adapter is on an upper stage which has engines underneath it, adding decouplers at the bottom of the engines and an upside-down one-to multiple adapter can allow for a large launcher underneath a powerful interplanetary vehicle. But only one of the decouplers are connected to the adapter below. This is very unstable and needs to be supported by struts.

Another, unconventional use of those parts is as a landing 'foot' when landing very large craft (such as bases). The stock landing legs aren't big or powerful, even though in version 0.22.0 they were re-modeled to include pistons for making a landed craft more stable. Using the strut parts as 'legs' and an adapter such as the Tri-Coupler as a 'foot', it can artificially make its own landing leg. Although, it will be mostly useless on sloped terrain, since it, unlike the landing legs, wouldn't have any pistons for keeping it from falling over on a slope.

Testing shows that the "tall" variety of adapters perform better aerodynamically than the "flat" variety, enough to offset the difference in weight. This means that when lifting off from a planet with an atmosphere, a larger delta-v is obtained when using the former (unless of course the part is protected from wind forces, for example using a fairing). The opposite is true when lifting off from a vacuum planet, due to the lower mass of the "flat" variety.

Types

Parts

Image	Part	Radial size	Cost ()	Mass (t)	Max. Temp. (K)	Tolerance (m/s)	Tolerance (g)
	FL-A10 Adapter	Tiny, Small	150	0.05	2 000	6	50
	Rockomax Brand Adapter	Small, Large	500	0.1	2 000	6	50
	FL-A5 Adapter	Tiny, Small	100	0.04	2 000	6	50
	Rockomax Brand Adapter 02	Large, Small	450	0.08	2 000	6	50
	BZ-52 Radial Attachment Point	Small, Radial mounted	250	0.04	2 000	10	50
	Rockomax HubMax Multi-Point Connector	Small	900	1.5	2 000	15	50
	Structural Fuselage	Small	380	0.1	2 000	10	50
	TVR-200 Stack Bi-Coupler	Small, Small x 2	400	0.1	2 000	9	50
	TVR-1180C Mk1 Stack Tri-Coupler	Small, Small x 3	680	0.15	2 000	12	50
	TVR-2160C Mk2 Stack Quad-Coupler	Small, Small x 4	2 000	0.175	2 000	12	50
	TVR-200L Stack Bi-Adapter	Large, Small x 2	400	0.1	2 000	12	50
	TVR-300L Stack Tri-Adapter	Large, Small x 3	600	0.15	2 000	12	50
	TVR-400L Stack Quad-Adapter	Large, Small x 4	800	0.2	2 000	12	50
	Mk3 Engine Mount	Mk3	2500	0.7	2 600	50	50

Fuel tanks acting as adapters

Liquid fuel and oxidizer density are both 5 kg/unit				Mass (t)					Liquid Fuel ()	Oxidizer ()
Image	Part	Radial size	Cost ()	Full	Empty	Max. Temp. (K)	Tolerance (m/s)	Tolerance (g)
	C7 Brand Adapter - 2.5m to 1.25m	Small, Large	800 (433.0)	4.57	0.57	2 300	20	50	360	440
	C7 Brand Adapter Slanted - 2.5m to 1.25m	Small, Large	800 (433.0)	4.57	0.57	2 300	20	50	360	440
	Mk2 to 1.25m Adapter	Small, Mk2	550 (366.4)	2.29	0.29	2 500	50	50	180	220
	Mk2 to 1.25m Adapter Long	Small, Mk2	1 050 (682.8)	4.57	0.57	2 500	50	50	360	440
	Mk2 Bicoupler	Small, Mk2 x 2	860 (676.4)	2.29	0.29	2 500	50	50	180	220
	2.5m to Mk2 Adapter	Large, Mk2	800 (432.8)	4.57	0.57	2 500	50	50	360	440
	Mk3 to Mk2 Adapter	Mk2, Mk3	2 200 (1 282.0)	11.43	1.43	2 600	50	50	900	1 100
	Mk3 to 2.5m Adapter	Large, Mk3	2 500 (1 353.0)	14.29	1.79	2 600	50	50	1 125	1 375
	Mk3 to 2.5m Adapter Slanted	Large, Mk3	2 500 (1 353.0)	14.29	1.79	2 600	50	50	1 125	1 375
	Mk3 to 3.75m Adapter	Extra large, Mk3	2 500 (1 353.0)	14.29	1.79	2 600	50	50	1 125	1 375
	Kerbodyne ADTP-2-3	Large, Extra large	1 623 (246.0)	16.88	1.88	2 000	6	50	1 350	1 650

Radial size	Tiny	Small	Large	Extra large
1× Small	FL-A5 Adapter FL-A10 Adapter NCS Adapter Modular Girder Adapter	—	Rockomax Brand Adapter 02 Rockomax Brand Adapter	Kerbodyne ADTP-2-3
2× Small	—	TVR-200 Stack Bi-Coupler	TVR-200L Stack Bi-Adapter	—
3× Small	—	TVR-1180C Mk1 Stack Tri-Coupler	TVR-300L Stack Tri-Adapter	—
4× Small	—	TVR-2160C Mk2 Stack Quad-Coupler	TVR-400L Stack Quad-Adapter	—