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DBooots / KerbalWindTunnel

A mod for Kerbal Space Program to provide atmospheric performance data for spaceplanes and aircraft.
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The effects of KSP's janky fairings on Wind Tunnel #17

Open FastAndFishious opened 2 years ago

FastAndFishious commented 2 years ago

This is just the detailed explanation of the fairing issues, nothing new. There are two cases that I know of where a faring's drag cube in the SPH/VAB is inaccurate.

Let’s start with an arbitrary fairing. Capture d’écran (112)

After “reloading” the craft, the values are incorrect. Reloading is caused by a lot of actions: reverting flight, switching editor, reopening the craft, or just undoing. Capture d’écran (113)

If a solution for this isn’t found, then at least there is a simple solution: changing the number of sides will force the game to recalculate the drag cube. However, the new values will still be off if the fairing is “expanded” by the mouse cursor. Capture d’écran (114)

Disabling fairing expansion or putting the cursor far enough away fixes this issue, and the value are correct. Capture d’écran (115)

However, you have been tricked! None of these values were actually accurate, because the fairing was the root part, which is too hot for KSP to handle, so it use the base’s drag cube alone. Capture d’écran (116) Capture d’écran (111)

After changing the root part, the values in the editors, and therefore those currently used by Wind Tunnel, are finally right. Capture d’écran (117)

This problem is more significant, since completely eliminating the shell’s drag while keeping its occlusion properties is a powerful exploit, but because Wind Tunnel does not take this bug into account, it becomes much harder to perfectly balance the pitching torque.

DBooots commented 2 years ago

This is fascinating. Do I want to reproduce the intended in-game behavior or the actual in-game behavior? Do I want this aerodynamic analysis mod to enable aerodynamic exploits that weren't intended by the devs?

I don't even know if I have enough control over procedural drag cubes in the editor to fix even the first part of the behavior you documented.

Kerbinator-Fras commented 2 years ago

janky root fairing is always used to create extreme low-drag craft, for example heatshield winged craft. However in KWT1.3.1 my heatshield winged craft's L/D is already normal, so not a big problem?

Kerbinator-Fras commented 2 years ago

janky root fairing is always used to create extreme low-drag craft, for example heatshield winged craft. However in KWT1.3.1 my heatshield winged craft's L/D is already normal, so not a big problem?