Bug #20683
Updated by Anonymous almost 6 years ago
Many of the new engines in Making History expansion have variants models, often with and without tank butts.
1) The PartDatabase.cfg is populated with drag-cubes that correspond to the areas and shapes of these engines +with shrouds attached+. This produces drag in-game that can be surprising if you chose an engine that would fit the stack without its shroud. (Usually the drag-cube has 'Shielded' and 'Clean' entries but this is turned off with useMultipleDragCubes = false in the new engines, probably to let the drag-cube entries line up simply with the variants.)
2) The models with shrouds have holes passing thru so the drag areas do not fill the expected {1.5, 2.5, 3.75}-meter-diameter circles. This leaves an area mismatch in the joints of a stack, and KSP applies flat-plate drag that users would not expect, similarly to the behaviour of tubes in #19376.
The drag a player feels is very sensitive to mismatches in area where two parts join along the stack. Desired behavior is to have at least the ends with nodes have areas in the drag model matching the visible area of the model, with any holes filled in, which often results in an area very near (nominal diamter)² × pi/4
Something like the Kodiak, with three variants and shroud/no-shroud configurations, would seem to need 6 drag-cube entries for the 6 possible visible shapes.
1) The PartDatabase.cfg is populated with drag-cubes that correspond to the areas and shapes of these engines +with shrouds attached+. This produces drag in-game that can be surprising if you chose an engine that would fit the stack without its shroud. (Usually the drag-cube has 'Shielded' and 'Clean' entries but this is turned off with useMultipleDragCubes = false in the new engines, probably to let the drag-cube entries line up simply with the variants.)
2) The models with shrouds have holes passing thru so the drag areas do not fill the expected {1.5, 2.5, 3.75}-meter-diameter circles. This leaves an area mismatch in the joints of a stack, and KSP applies flat-plate drag that users would not expect, similarly to the behaviour of tubes in #19376.
The drag a player feels is very sensitive to mismatches in area where two parts join along the stack. Desired behavior is to have at least the ends with nodes have areas in the drag model matching the visible area of the model, with any holes filled in, which often results in an area very near (nominal diamter)² × pi/4
Something like the Kodiak, with three variants and shroud/no-shroud configurations, would seem to need 6 drag-cube entries for the 6 possible visible shapes.