Hi!What is SAS and RCS?

[BadBoy'98]

Can you explain please?

[ScruffyBamboo]

SAS is a system that allows you to "lock in" a direction, and have the system TRY to keep the craft pointing that way. It's a series of computer controlled gyros that stabilise the rocket.

RCS is a system of small directional thusters (using monopropellant), usually used for fine maneuvering in space. Like SAS, RCS can help with rotation control, but UNLIKE SAS, it can also be used for movement (up, down, left, right, fowrard, back), much like a Kerbal's jetpack. In fact, RCS is very much a customizable "jetpack" for your rocket.

[Leigh]

SAS: Stability Control: Pilots and Probe Cores have the ability to help stable the craft. If you can activate it, hit the T key. A white SAS light appears on the navball. I pretty much keep it on all the time, so the Kerbals do not get space sick.

Use reaction wheels to add strength to SAS, 2-3 units should be enough for a whole rocket, and you will ditch one at a time witht he stages. Remember, your last stage will at least need the small wheel, as most Pods do not have the torque you need.



RCS: Reaction Control Systems. Little thrusters mostly used for docking, but can help stablize craft. Hit the R key to see the green RCS light appear on the navball. Please see tutorials and wikis on how to use them for docking (in docking mode, not standard mode) as the controls differ.

You will need a supply of Monopropellent for RCS thrusters and some engines use it too.

[The_Mell]

There are different methods to control your vessel:
- torque (generated by pods, probe cores and special parts, needs electricity to operate)
- aerodynamic control surfaces (only in atmosphere and while moving)
- gimbal of engine (pushing your vessel not straight, not all engines)
- RCS, little thrusters pushing your vessel (you need those thrusters and they need fuel, mostf of them monopropellant)


SAS stands for Stability Assist System
The basic feature is that it holds (or at least tries to hold) your vessels current orientation if activated permanently after pressing 'T' or temporary while pressing 'F'.
This way it is usually much easier to fly because this simple autopilot keeps you most of the time 'on track' while you can do adjustments to your wished course.
It's like driving a car down a straight road and only touch the steering wheel during the curves.
Advanced feature of trained pilots or better probe cores allow you to automatically change your vessels orientation by clicking asymbol next to the navball to easier do orbital maneuvers.

[BadBoy'98]

Thank you!

[Leigh]

Happy crashin... I mean,. happy flying! :)

[Langkard]

One warning about using SAS that I didn't see mentioned above. The reaction wheels require electric charge to operate. Many of the engines generate electric charge while thrusting, which is fine. But when the engines are not firing and you don't have a way of generating power, such as solar panels or stored power in batteries, you will quickly run out of electric charge using SAS. So, make sure you have batteries and that you include enough for the mission, until you have the tech for power generation options like solar panels or fuel cells.

It really sucks when you get into space and want to make a maneuver but you can't turn the rocket to the maneuver direction because you ran out of electric power.

[BadBoy'98]

Ok

[El Rushbo]

Proper placement of RCS thrusters is also vital for the system to work properly. Keep the crafts center of mass in mind when placing them, the same goes for reaction wheels. All the torque in the world won't do you any good if it's on one side of a large craft.

[MAD]

RCS is vital for docking, other than that you don't need it. Don't waste your Delta V by adding unecesary mass.
Place RCS as far from the axis of rotation as you can, but keep it symetrical.
20kN.m of torque = 20kN of thrust at 1m = 2kN of thrust at 10m's
http://steamcommunity.com/sharedfiles/filedetails/?id=460438430&fileuploadsuccess=1
Stability Assist is the primary way of rotating your craft in space but is most often used to prevent your ship from flipping while banking in an atmosphere. Fins only work if there is air to push against, SAS works everywhere but it can only provide so much torque.
When in doubt adda another SAS (or if your desperate some RCS)
Conservation of rotational momemtum - it doesnt matter where you place your SAS, centre of mass is just as good as one edge. If you have a power drill and a swivel chair you can test this.

One thing RCS can do that SAS cant do is act like a little rocket, you can even use it to land light stuff on the mun or reenter if your stranded in orbit.


Advanced inline stabilizer ............ 100kg 15kN.m torque
4x RV-105 RCS thrucster blocks ...200kg 4kN thrust
1x FL-R25 RCS fuel tank.............1150kg

If you don't believe me you can just test it for youself

[SievertChaser]

To say it more broadly, and more sciency, RCS allows you to translate (move) your ship. You will have a lot of problems docking without RCS, although some nutcases believe you should do it with main thrusters.