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→RCS DAP schemes
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=== RCS DAP schemes === | === RCS DAP schemes === | ||
The real Space Shuttle has a multitude of (partially mission-specific) DAP schemes, each with different gains and deadbands, which control the thruster firing pattern in response to the controllers. A fair selection of these is implemented in FG. In the real Shuttle cockpit, there is both a rotational hand controller (RHC) and a translational hand controller (THC) to initiate either rotations of the shuttle or translational accelerations (e.g. for approach and docking). In FG, {{ | The real Space Shuttle has a multitude of (partially mission-specific) DAP schemes, each with different gains and deadbands, which control the thruster firing pattern in response to the controllers. A fair selection of these is implemented in FG. In the real Shuttle cockpit, there is both a rotational hand controller (RHC) and a translational hand controller (THC) to initiate either rotations of the shuttle or translational accelerations (e.g. for approach and docking). In FG, {{Key press|m}} corresponds to switching from THC to RHC and back, {{Key press|Shift}} + {{Key press|m}} switches between the different DAPs and {{Key press|Control}} + {{Key press|m}} is the override switch to aerodynamical controls. The HUD will display the currently selected mode for clarity. | ||
Due to the geometry of the thruster arrangement, there is significant mode mixing. For instance, a lateral translation firing nose and right pod thruster with the same thrust would also induce a yaw motion (since the modules do not have the same distance to the CoG) and a roll (since they are not in the CoG plane and in fact not even in the same plane). In most implemented modes, the FCS logic takes care of most of these effects by firing additional thruster to cancel the unwanted motion, however in some modes this is not easily possible and mode mixing has to be anticipated and accounted for manually. This is in fact the same as in the real Shuttle. | |||
<b>RCS rotation:</b> This is a simple scheme in which the stick motion controls thrust, i.e. angular acceleration. Stick to neutral commands no thrust, i.e. the Shuttle will continue its current rotation. | |||
<b>RCS DAP-A:</b> A precision 'stick controlls rate' scheme in which stick to neutral commands an attitude hold. The mode has fairly strict deadbands and steep gains and hence uses comparatively much propellant to stabilize attitude. | |||
<b>RCS DAP-B:</b> As DAP-A, but more permissive in terms of deadbands, trades less strictly stabilized attitude against reduced propellant consumption. | |||
<b>RCS ROT TAIL ONLY:</b> A 'stick controls thrust' scheme in which the nose module is not used. This causes significant mode mixing. | |||
<b>RCS ROT NOSE ONLY:</b> A 'stick controls thrust' scheme in which the OMS pod modules are not used. This causes significant mode mixing and has no roll control available (it would have some very limited roll control in reality). | |||
<b>RS ROT ENTRY:</b> A 'stick controls rates' DAP designed for entering the atmosphere which enforces a 'no sideslip' attitude in which the nose module is not used. This has very strict deadbands and agressive gains to combat the yaw instability of the Shuttle upon entry, significant mode mixing and is very propellant-consuming. Do not use in orbit and only activate at the entry interface once the shuttle has the correct attitude! | |||
== Glossary of acronyms == | == Glossary of acronyms == | ||