Aid tool for balancing RCS thrusters around the center of mass while building a rocket, and a bit more.
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KSP version 0.24.2
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blizzy78’s toolbar http://forum.kerbalspaceprogram.com/threads/60863
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Display thrust and torque forces caused by RCS or engines.
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Delta V readout for RCS.
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Dry center of mass marker.
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Average center of mass marker.
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The CoM marker represents better the situation in flight.
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Ability to resize editor’s overlay markers.
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Display total amount/mass of resources.
This plugin can only be used while in VAB (Vehicular Assembly Building) or in SPH (Space Plane Hangar). RCSBuildAid is be enabled when you activate the Center of Mass (CoM) marker. Once enabled, you should see RCSBuildAid’s window.
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Note
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If you have blizzy78’s toolbar installed, then you enable it from the
toolbar. If you want to disable blizzy78’s toolbar for RCSBuildAid then you can
do it by deleting the file RCSBuildAidToolbar.dll or by changing the line
toolbar_plugin = True to False in the file settings.cfg.
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Having balanced RCS means that when you’re translating your vessel won’t rotate and when you are rotating it won’t translate, this is important for easy docking. This depends of the position of your CoM and the placement of your RCS thrusters.
The topmost button in the window is for select the working mode, each having a different purpose. Currently the modes available are:
For balancing translation. The installed RCS will be set to translate your vessel to the current direction, with the green arrow being the actual resulting motion. When balancing translation you want translation motion without any rotation, so you want to place your RCS around your CoM in a way that reduces the torque vector (red arrow) as much as possible.
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Note
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Is not necessary to completely cancel out the torque force, sometimes might be difficult. If you don’t see the circular arrow then it means that the current torque is acceptable and shouldn’t interfere during normal docking. |
For balancing attitude. Only with RCS, reaction wheels and engine’s gimbals not accounted. For balancing attitude you want to reduce the translation vector (green arrow) while keeping the torque vector aligned with the red marker. In most vessels you won’t need to do this since balanced translation implies balanced rotation, but this is not always true.
The forces displayed are of 3 types:
- Part forces
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Forces exerted by parts, they are colored cyan for RCS and yellow for engines.
- Translation force or thrust
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Colored in green, represents the translation motion of your vessel, essentially your vessel’s thrust. A small green triangle near the tip of the arrow indicates where it should be pointing ideally.
- Torque force
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Colored in red, represents the resulting torque the thrusters are exerting into your vessel. The effect of this torque is represented by a circular arrow, which is proportional to the expected angular acceleration. When you see a red arrow, it means that in the current configuration and with the given input your vessel will try to rotate, however, depending of your vessel’s mass and of its distribution this rotation might not be noticeable, you can gauge this with the circular arrow. Like in the translation force, a small red triangle would be indicating the ideal direction.
- CoM
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The Center of Mass marker, colored yellow. You should be familiar with this one, and if you’re a savvy KSP player you will know that some parts, while being listed as having mass in the editor, actually don’t have any during playtime, the most egregious offender being the small gear bay used for planes. This means that the CoM marker in the stock game isn’t accurate when using these parts, but RCS Build Aid fixes it.
- DCoM
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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
Resourcessettings. - ACoM
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This is the Average Center of Mass marker, colored orange, shows the middle point between the CoM and DCoM.
All forces are referenced to one of these markers, you select which one from the GUI. Checking how forces change depending of where your CoM is will help you to understand how to balance best your vessel, eg, 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 center of masses as close as possible, or if you can’t achieve this, balancing around the ACoM marker would be the best compromise.
RCS Build Aid’s window have several sections showing some information and options.
Shows some information regarding the current mode in use, usually the thrust and torque magnitudes, and buttons for change the current direction and center of mass (CoM, DCoM or ACoM).
- Torque
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Torque magnitude.
- Thrust
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Thrust magnitude.
- Reference
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Active center of mass of the vessel, click for change.
- Direction (Translation and attitude modes)
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Current movement direction, click for change or use the shortcuts.
- Delta V (Translation mode only)
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Available dV from RCS at current direction.
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Note
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Delta V readout has some issues, see Known issues section. |
- Burn time (Translation mode only)
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Time RCS will last until running out of fuel at current direction.
- TWR (Engine mode only)
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Thrust to weigth ratio at Kerbin sea level.
Shows some information regarding the mass of the vessel.
- Wet Mass
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Total mass of the fully fueled vessel.
- Dry Mass/Fuel Mass
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Mass of the vessel without fuel / Mass of the fuel, click in label to toggle.
- DCoM offset
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Distance between the CoM and the DCoM.
Shows a list of resources currently in your vessel, displaying the total mass or the total amount of each (click in the "Mass" label for change the reading).
You can select which resources should be used for calculating the DCoM position and the vessel’s dry mass, disabled resources will be removed and enabled ones will remain. For example, if you want to know your vessel’s mass and DCoM position when only the MonoPropellant is completely consumed, only disable the MonoPropellant.
You can change direction from the GUI, or alternatively with the same keys for translating your vessel. If default game settings the keys are:
| H |
Set direction forward. |
| N |
Set direction backwards. |
| L |
Set direction right. |
| J |
Set direction left. |
| I |
Set direction down. |
| K |
Set direction up. |
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Note
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Setting the same direction twice disables current mode. |
This plugin will work only with parts using stock modules, such as ModuleRCS
or ModuleEngine. Modded parts that use other modules will not be detected by
RCS Build Aid.
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Delta V readout for RCS isn’t very smart and only works for the stock RCS that use monopropellant, there will be no dV readout if the RCS uses other fuel or a different flow mode (like Vernor RCS).
This project picks its references for a local directory for avoid commiting the
absolute path of library files into the repository. So if you want this project
to find its references without changing any project files you have create a
local directory named Libraries and copy (or symlink) the directory Managed
from a KSP install and Toolbar.dll from blizzy78’s toolbar mod (if you wish to
compile RCSBuildAidToolbar.dll).
Libraries\
Managed -> ${KSP_DIR}/KSP_Data/Managed
Toolbar.dll -> ${KSP_DIR}/GameData/000_Toolbar/Toolbar.dll
You can report bugs or issues directly to GitHub: https://github.com/m4v/RCSBuildAid/issues
Curse site: http://curse.com/project/220602
Repository in GitHub: https://github.com/m4v/RCSBuildAid
Forum thread: http://forum.kerbalspaceprogram.com/showthread.php/35996
This plugin is distributed under the terms of the LGPLv3.
This program is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with this program. If not, see <http://www.gnu.org/licenses/>.