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Space Shuttle: Difference between revisions
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→Payload handling with the RMS arm
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Apart from these, the Shuttle HUD contains a basic engine status display, speedbrake, body-flap and gear status indicators in the approach mode and yaw, pitch and roll rate indicators in orbit, as well as the normal pitch ladder and flightpath indicator of an airplane. | Apart from these, the Shuttle HUD contains a basic engine status display, speedbrake, body-flap and gear status indicators in the approach mode and yaw, pitch and roll rate indicators in orbit, as well as the normal pitch ladder and flightpath indicator of an airplane. | ||
== Payload handling | == Payload handling == | ||
The Space Shuttle is equipped with the capability to release payload from the bay into space, or to catch a payload from space and deposit and secure it in the bay. For this, the Remote Manipulator System (RMS) arm in combination with the payload latching system is used. | |||
[[File:Payload_ops03.jpg|600px|thumbnail|none|Handling a payload with the RMS arm]] | [[File:Payload_ops03.jpg|600px|thumbnail|none|Handling a payload with the RMS arm]] | ||
=== RMS arm operation === | |||
The RMS arm is a fairly complicated device with six different joints, each allowing rotation along one specific axis, which is formed after the human arm. The nomenclature is borrowed from this analogy, so there is a shoulder yaw, a shoulder pitch, an elbow pitch, a wrist pitch and wrist yaw and roll joints. Each of the joints can only be moved a certain angular range. At the end of the RMS arm is the end effector which is the device which can attach to a payload. | |||
The RMS arm can be driven in various modes. The simplest of these are the single joint or the direct mode in which each joint angle is controlled separately, i.e. the arm is extended by first selecting a joint, then commanding it to either increase or decrease angle, before the next joint is selected. | |||
Since this is cumbersome, the more natural control modes allow to use the stick (or whatever control device is attached) to directly move a reference point. In the ORB UL x/y/z mode (UL stands for 'unloaded') the reference point is the tip of the end effector, i.e. using the stick just moves the joint angles such that the end effector moves along the x, y, or z-axis and otherwise keeps its attitude. The ORB UL yaw/pitch/roll mode in contrast keeps the end effector's position and just changes its attitude. | |||
The real Shuttle has additional modes in which the reference point is in the center of the payload, or in which the reference coordinate system is changed from the Shuttle's coordinate system to a system co-moving with the end effector camera - these are as of August 2015 not implemented in FG. | |||
All modes except single and direct joint driving have software safety stops when the joints approach their limit extensions. Since in its stowed position, two of the joints are in the software stop region, it is necessary to directly drive shoulder pitch and elbow pitch out of their soft stop region to be able to use the more sophisticated control modes. | |||
Finally, the RMS arm is secured by a shoulder brace to make it cope with launch acceleration. This brace needs to be removed before the arm can be operated, and the arm itself needs to be powered, deployed and unlatched. | |||
=== Payload retention system === | |||
The payload retention system is a series of latches which hold a payload in the bay. Before a payload can be lifted out of the bay, these latches need to be released. Similarly, if a payload is returned into the bay, ready-to-latch indicators show when it has reached the correct stowing position and it can only be safely released from the RMS arm once the latches are closed. | |||
The real Shuttle has three different payload positions with corresponding latch controls, as of August 2015 only one payload position is supported in FG. Likewise, currently only a simple demo satellite with no proper folding/unfolding animation is available as visual payload (note that a payload mass affecting the FDM can also be chosen in the 'Fuel and Payload' dropdown menu). | |||
== Mission phases == | == Mission phases == | ||