If you end up controlling the "dead" end of the rocket after stage separation, simply press the "" keys to select the appropriate section. Right click the unit and select "Control From Here" to change the control point. This can be accomplished by placing a command module or docking port in the middle of the rocket. For this reason, "wobble" can be largely eliminated by controlling the vessel as close to the CG as possible. This means that large rockets that tend to wobble out of control during flight do so because the SAS sees the tip (where the command module usually is) rotating and assumes the entire vessel is spinning this fast. The PID control is applied to the vessel's rotational velocity at the command point. This is supposed to dampen the action of the S.A.S module and prevent overshoot, as well as dampening any accelerating turn or roll.
So the faster the ship is going "into" the spin, the harder the S.A.S. module takes the angular acceleration of the ship into account and tries to apply a force against it. Since the summed integral value is set to zero when SAS is turned on, the controller will attempt to lock the vessel's heading to whatever it was when SAS was turned on. Since the integral of speed is position, this corrects the vessel's heading (angle is the integral of angular velocity). module increases the corrective force the longer the ship is off-target. In other words, the faster the ship is spinning, the harder the module tries to correct the spin. module applies a turning-force that is proportional to the speed of rotation. The PID is applied to the vessel's angular velocity, not its heading. system, which stands for “Proportional, Integral, Derivative”. Please help Kerbal Space Program Wiki by fixing inaccurate or outdated information. This page or section is in need of being brought up to date. ↑ dedicated SAS units don't work without command modules.comment by C7, in his blog entry “ Updated Information on SAS in 0.21.1” You'll get offcenter rotation anywhere other then near the COM. That is what the reaction wheels will try to do. Imagine you are grabbing that point and rotating it. Generally speaking they can cause some problems if placed far from the center of mass. The placement does matter for reaction wheels. Though manned command modules will tend to be at the front of the craft for visibility in IVA, SAS modules in general are best placed close to the center of mass, especially those with more torque. Placement should be considered while building craft in the editor. Pilot kerbonauts have a levelled progression of directions they can point toward.īeware, having SAS activated while deploying a parachute may cause the parachute to rip off due to the SAS attempting to stabilize the craft's sudden rotation to orient in the wind. But the user can select other vectors depending on the capabilities of the probe core/pilot such as prograde, retrograde, normal, antinormal, radially in/out, and target prograde/retrograde. By default "stability assistance" is selected and stabilizes on the current heading. If only "stability assistance" is available, no selectors will appear. While SAS is turned on, if any capabilities are available beyond stability assist, a direction selector will appear to the left of the navball. The current state of the SAS system is shown by a blue light on the navball. The system can be toggled with (by default) the T key and temporarily switched by holding down the F key (for example, if SAS is on, holding F will turn it off, and releasing F will turn it back on). Control surfaces (only effective in atmosphere).It will utilize all active control systems to achieve this, like the user would by pressing the keys.
When active, the SAS itself doesn't drain electricity, though reaction wheels may continue fine-tuning even in space. Since it controls heading, it can be extremely useful for lander missions. The user can override the current rotation for any axis. When active, SAS will provide input to stability systems to dampen craft rotation and, depending on capabilities, lock onto a specific orientation. In Sandbox mode there is no restriction on SAS. At least one kerbonaut manning a command module must have the Pilot specialization to use SAS. All robotic command modules except the Stayputnik Mk. SAS is an automatic system toggled on or off during flight.įor SAS to be available at all in career mode, the craft must include an unmanned pod (probe core) with SAS capability or, since version 0.90.0, a pilot.