RCSBuildAid

= RCS Build Aid Plugin: Documentation Elián Hanisch lambdae2@gmail.com v1.0.4, December 2020: :imagesdir: doc

This is a plugin for https://www.kerbalspaceprogram.com[Kerbal Space Program] and is an aid tool for balancing RCS thrusters around the center of mass while building a rocket, and a bit more.

image::intro.jpg[width="600",align="center"]

== Requirements

• KSP version 1.11.x

=== Supported mods

• Alternate toolbar, https://forum.kerbalspaceprogram.com/index.php?/topic/161857-*[blizzy78's toolbar].
• Update notifications, https://forum.kerbalspaceprogram.com/index.php?/topic/173126-*[KSP-AVC plugin].

== Features

• Display thrust and torque forces caused by RCS or engines.
• Torque by engine gimbals.
• Dry center of mass marker (DCoM).
• Average center of mass marker (ACoM).
• Center of drag marker (CoD) for assisting in parachute placement.
• ΔV readout for MonoPropellant RCS.
• Ability to resize editor's overlay markers.
• Display total amount/mass of resources.

== Installation

• Download the latest version from https://www.curseforge.com/kerbal/ksp-mods/rcs-build-aid[CurseForge]
• Unzip and copy RCSBuildAid directory into your KSP's GameData directory.

=== Files

The files that you should have after installing RCS Build Aid in GameData/RCSBuildAid are:

• Plugins/ ** RCSBuildAid.dll The main plugin. ** RCSBuildAidToolbar.dll This plugin adds support for blizzy78's toolbar. Can be deleted if you don't use it. ** PluginData/ *** settings.cfg RCS Build Aid config. Can be deleted to reset all settings.
• Textures/ ** iconAppLauncher.dds ** iconToolbar_active.dds ** iconToolbar.dds
• CHANGELOG.adoc
• README.adoc Documentation.
• README.html Documentation in html format.
• LICENSE
• RCSBuildAid.version Used by some tools to check for updates, such as KSP-AVC plugin.

== User interface

This section explains all the readouts and overlays of the plugin, if you don't have time for that you can skip to <<Applications>> for some use cases.

=== Activating the plugin

This plugin can only be used while in VAB (Vehicular Assembly Building) or in SPH (Space Plane Hangar). RCS Build Aid is enabled by clicking in the application launcher button image:button.jpg[20,20] at the bottom of the screen. Once enabled, you should see its main window. You can also enable it by pressing the key 5, see <<Settings>> if you want to change the keyboard shortcut.

NOTE: If you have blizzy78's toolbar installed, then you can disable the application launcher button or blizzy78's toolbar from the <<Settings>> menu.

=== Editor overlays

image::overlays.jpg[width="300",role="right"]

The editor overlays are the markers and arrows over you vessel. With them you can see the effects of forces on your vessel and balance it at glance without needing to look at the numbers.

==== Forces

Forces are displayed as arrows, there are several types:

Part forces:: Forces or thrust exerted by parts, they are colored cyan for RCS and yellow for engines. They point towards the exhaust's direction so technically these arrows are the inverse of the actual force.

Thrust or translation force:: Colored in green, represents the translation motion of your vessel, essentially the total thrust applied to the vessel. A small green triangle near the tip of the arrow indicates where it should be pointing ideally.

Torque force:: Colored in red, represents the resulting torque the thrusters are exerting into the vessel. Like in the translation force, a small red triangle would be indicating the ideal direction.

Angular acceleration:: The angular acceleration is represented by a red circular arrow, its purpose is to indicate how fast a vessel will rotate under the effect of current torque. If there's torque but the circular arrow is small or not visible it means that the vessel is massive enough for not be significantly affected.

Drag force:: Colored in cyan, only seen in parachute mode. Shows the drag force of the vessel falling vertically at terminal velocity.

==== Markers

CoM:: The Center of Mass marker, colored yellow. This is the same as the stock CoM.

DCoM:: The Dry Center of Mass marker, colored red, indicates the center of mass for your vessel without resources. Which resources to remove when the vessel is "dry" can be configured from the <<Resource settings>>.

ACoM:: This is the Average Center of Mass marker, colored orange, shows the middle point between the CoM and DCoM. Is enabled from the <<Marker settings>>.

Both translation and torque forces are referenced to one of these markers, you select which one from the main window. Checking how forces change depending of where your CoM is will help you to understand how to balance best your vessel. For example, for a vessel that docks with almost no fuel it would be best to balance RCS around the DCoM and ignore the CoM marker. If you want your vessel to be balanced in most situations you need to build your vessel in a way that keeps both CoM and DCoM as close as possible, or if you can't achieve this, balancing around the ACoM marker would be the best compromise.

[[CoD]] CoD:: The Center of Drag, only enabled while in <<Parachutes>> mode. Don't confuse this marker with stock's Center of Pressure (CoP).

=== Main window

image::main_window.jpg[role="right"]

RCS Build Aid's window have several sections showing some information and options.

==== Mode section

The topmost part of the main window is the mode section. Allows switching modes and shows information relevant to the active mode, see <<Modes>>.

==== Vessel mass

Shows some information regarding the mass of the vessel.

Wet Mass:: Total mass of the fully fueled vessel.

Dry Mass/Fuel Mass:: Mass of the vessel without fuel or the mass of the fuel, click in label to toggle. They both depend of the resource settings, see below.

==== Resource settings

Shows a list of resources currently in your vessel, displaying the total mass or the total amount of each (click in the Mass label to change the reading).

The DCoM position and the vessel's dry mass is calculated based on the selected resources here, disabled resources will be seen as "dry" and enabled ones will be seen as full. For example, in the image above the DCoM marker will be at the center of mass of the vessel when the Oxidizer and LiquidFuel tanks are empty but MonoPropellant tanks are full.

NOTE: Fuel from tanks where the fuel flow is blocked won't be removed from the DCoM.

==== Marker settings

Options to show, hide or change the size of the CoM markers. See <<Markers>> for a description of each.

==== Collapsing the main window

If the main window is bothering but you need RCS Build Aid to be active you can collapse it by clicking the small button at the end of title bar, right of the s settings button.

Alternatively, any sections can be collapsed by clicking in their title button.

==== Settings

image::settings.jpg[role="right"]

You can open the settings menu from the small s button in the title bar of RCS Build Aid window.

Use application launcher:: Disable/Enable RCS Build Aid's button in the application launcher. If blizzy's toolbar isn't installed this option is not possible to disable and is greyed out.

Use blizzy's toolbar:: Disable/Enable RCS Build Aid's button in blizzy's toolbar. If blizzy's toolbar isn't installed this option is greyed out.

Show in Actions Screen:: Don't hide RCS Build Aid when switching to the action groups screen in the editor.

Show in Crew Screen:: Don't hide RCS Build Aid when switching to the crew screen in the editor. Mostly to see the effects of mass changes when adding kerbals to the vessel.

Show in Cargo Screen:: Don't hide RCS Build Aid when switching to the cargo screen in the editor. Mostly to see the effects of mass changes when adding cargo.

Marker autoscaling:: The CoM markers will change size depending of the camera distance (if you get the camera closer to your vessel the markers will shrink).

Massless resources:: If enabled show massless resources like ElectricCharge in the <<Resource settings>>. Has no use other than for seeing total amounts.

RCS TWR readout:: If enabled will show the TWR (Thrust to Weight Ratio) of RCS.

DCoM offset readout:: If enabled will show the distance between CoM and DCoM markers in the mass section.

GUI scale:: This setting is for increasing the size of the GUI, for high resolution monitors.

Shortcut:: Enable RCS Build Aid with a keyboard shortcut, key 5 by default. You might assign any key but no key combinations. Pressing ESC disables it.

=== Modes

The topmost button in the main window is for select the working mode, each having a different purpose. Currently the modes available are:

==== Translation

For balancing translation movement.

image::translation_mode.jpg[align="center"]

This mode will activate RCS and show how they will fire for a given direction of motion. The green arrow will show the resulting thrust, thus the actual motion and any imbalances will be reflected in the torque.

Reference:: Active center of mass of the vessel, clicking the button will cycle between the active markers.

Direction:: Current movement direction, click to change or use the <<Keyboard shortcuts>>.

Torque:: Total torque magnitude.

Thrust:: Total thrust magnitude.

ΔV:: Available delta velocity from RCS at current direction.

NOTE: The ΔV readout has some issues and will not show for all RCS, see <<Known issues>>.

Burn time:: Time RCS will last until running out of fuel at current direction.

NOTE: The burn time readout has the same issues of the ΔV readout, see <<Known issues>>.

Body:: If the TWR readout is enabled, this will show the selected celestial body for TWR calculations, click to change.

TWR:: Thrust to weight ratio, this depends of the selected celestial body and is always calculated for gravity at sea level. This readout needs to be enabled from the <<Settings>> menu.

NOTE: Because RCS thrust is al