Control surface

adjusting the reaction to the different axes

A control surface is an aerodynamic part that provides reactive force when in motion relative to the surrounding atmosphere. Control surfaces provide greater control and stability to rockets and aircraft, though they are of no use outside of an atmosphere.

Each of the control surfaces has tweakables to enable or disable each control axis. Disabling undesired axes can prevent the craft from over-reacting to control inputs. These can be done in the SPH or VAB, and even after launch (except State).

To provide a good level of control in a given axis, they should be placed far away from the center of mass in the appropriate direction:

• Pitch (elevators): lifts and lowers the nose of the craft around the pitch axis, running from left to right through the center of mass. Typically placed on the horizontal tail fins.
• Yaw (rudders): turns the craft left and right around the yaw axis, running up and down through the center of mass. Typically placed on the vertical tail fin(s).
• Roll (ailerons): rolls the craft around the longitudinal axis, running from nose to tail through the center of mass. Typically placed at the end of the wings.

The Active/Inactive label by the axis indicates whether the control surface responds to input in the given axis.

• State: The default state of the control surface - Normal/Deployed
• Deploy: The direction of the extension - Normal/Inverted

The control surfaces can be also controlled by action groups:

• Toggle
• Extend
• Retract

This retraction represents extending flaps, which increases lift and drag, thus reducing stall speed. This is useful for reducing speed and altitude while maintaining a level attitude for a landing approach. It may be a good idea to start with flaps deployed and bind toggling them to the "gears" action group.

Table of Control Surfaces

Image	Part	Radial size	Cost ()	Mass (t)	Max. Temp. (K)	Tolerance (m/s)	Tolerance (g)	Lift	Deflection Range (°)	Deflection Surface Part (%)
	AV-R8 Winglet	Radial mounted	640	0.1	2 400	12	50	0.5	15	95
	Standard Canard	Radial mounted	720	0.1	2 400	12	50	0.5	15	100
	Advanced Canard	Radial mounted	800	0.08	2 400	12	50	0.4	10	100
	Delta-Deluxe Winglet	Radial mounted	600	0.078	2 400	12	50	0.65	25	20
	Tail Fin	Radial mounted	600	0.125	2 400	12	50	0.61	25	100
	FAT-455 Aeroplane Tail Fin	Radial mounted	1 000	0.36	1 200	15	50	2.69	15	37
	Big-S Spaceplane Tail Fin	Radial mounted	2 500	0.45	2 400	15	50	3.49	25	29
	Elevon 1	Radial mounted	400	0.05	2 400	15	50	0.25	20	100
	Elevon 2	Radial mounted	550	0.06	2 400	15	50	0.30	20	100
	Elevon 3	Radial mounted	650	0.08	2 400	15	50	0.42	20	100
	Elevon 4	Radial mounted	400	0.04	2 400	15	50	0.18	20	100
	Elevon 5	Radial mounted	800	0.08	2 400	15	50	0.4	20	100
	Big-S Elevon 1	Radial mounted	950	0.15	2 400	15	50	0.77	25	100
	Big-S Elevon 2	Radial mounted	1 300	0.23	2 400	15	50	1.16	25	100
	FAT-455 Aeroplane Control Surface	Radial mounted	800	0.17	1 200	15	50	0.86	15	100
	A.I.R.B.R.A.K.E.S	Radial mounted	1000	0.05	1 200 (2 400)	8	50	0.38	70	100

See also

• Reaction wheels
• RCS thrusters