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Download the GPDS HOWTO to include in any CVE-lite vessels you create!

How do I use GPDS?

is the Generic Payload Description System as orginally implemented in Ariane 5 v1. Fundementally there are three commands. PAYLOAD, STAGE and ENDSTAGE.


PAYLOAD is the most basic GPDS token. It describe a dumb rider on the present rocket or other vessel. The format is:

PAYLOAD  name  meshname  classname  xposition yposition zposition  mass  xrotation  fuellevel
  • name is the user-defined name for the payload upon deployment
  • meshname is the path and filename (without .msh) of the mesh that describes the payload whilst attached.
  • classname is the path and filename (without .cfg) of the config file that describes the payload at deployment.
  • x,y,z positions are the spatial co-ordinates that define where the payload will be represented on the vehicle and where it will be jettisonned from. You will need to set this with trial and error.
  • mass is the all-up mass of the payload, including any fuel or other mass.
  • xrotation is the rotation, in degrees, around the x-axis that the payload should undergo whilst mounted. Not supported in beta version.
  • fuellevel is the proportion (from 0 to 1) of default propellant resource that should be afforded the payload upon creation. It is the users' responsibility to ensure the figure here is consistent with the all-up mass specified earlier.


STAGE indicates a branching in the payload structure. PAYLOADs specified before a STAGE entry are parented to the previous stage and those after are parented to the vessel defined in the STAGE line, up until an ENDSTAGE token is received. STAGEs must always be CVE-lite compatible vessels, else the passed-through payloads will vanish. If this is not clear, see the examples at the bottom of the page.

STAGE  name  meshname  classname  xpos ypos zpos  mass  xrot  fuellevel
Where the entries are the same as for PAYLOAD, above.


ENDSTAGE defines the end of the previous, and corresponding STAGE line. All PAYLOADs or STAGEs defined beyond this are the parents of the previous STAGE's parent, not of that STAGE itself.



PAYLOAD ProbeA probe probe 0 0 0 660 0 1
PAYLOAD ProbeB probe probe 0 0 3 660 0 1
PAYLOAD ProbeC probe probe 0 0 6 660 0 1
Launches three Probes, separated by three metre intevals, on the vessel centreline. Each has 100% fuel at jettison and weighs 660kg, all up.

STAGE Fregat fregat fregat 0 0 0 7000 0 1
  PAYLOAD MarsExpress ME_stowed ME_deployed 0 0 2 500 0 1
Launches an upper stage consisting of a fregat with a probe called MarsExpress on board. The fregat weighs 7000kg and has 100% fuel on board, the MarsExpress 500kg, also with 100% fuel. The MarsExpress uses a stowed mesh en route and spawns a "deployed" vessel upon jettison.

PAYLOAD ModuleA module2 module2 0 0 0 5000 0 0
STAGE Fregat fregat fregat 0 0 5 7000 0 1
PAYLOAD Probe probe probe 0 0 7 660 0 1
PAYLOAD CommSat carina carina 0 0 10 5000 0 0
Launches a stack consisting of a module-2 with a fregat-probe combination above it and a Carina satellite above that. Upon deployment the sequence of release will be: CommSat, Fregat-Probe, ModuleA. The fregat may then continue to manoevre with the probe attached, until it may then jettison the probe separately to the other payloads.