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Bug #25751

RFP flags at an angle introduce body lift onto the vehicle.

Added by dok_377 25 days ago. Updated 17 days ago.

Status:
Confirmed
Severity:
Low
Assignee:
-
Category:
Aerodynamics
Target version:
-
Start date:
07/09/2020
% Done:

10%

Version:
Platform:
Windows
Expansion:
Core Game
Language:
English (US)
Mod Related:
No
Votes:
Arrow u r green
Arrow d r red

Description

If you take a flag and place it on your craft at an angle, it will introduce body lift onto the parent part.

This is not supposed to be a thing, since flags are essentially just some paint on your craft.

Steps to reproduce:

1. Make a simple rocket.
2. Put a single flag on its side.
3. Rotate this flag 45 degrees and offset it slightly.
4. Launch your rocket upwards, enable the aero overlay and just wait.

The flag starts to introduce insane amounts of body lift onto its parent part once craft is moving relatively fast, essentially making the craft uncontrollable if you have a bunch of flags at an angle.

I made a video showing how it's all happening: https://youtu.be/fp5IvtRtC-E

Flag Test.craft (16.3 KB) Flag Test.craft The craft from the video. dok_377, 07/09/2020 03:32 PM

History

#1 Updated by k-ohara5a5a@oco.net 17 days ago

  • Status changed from New to Confirmed
  • % Done changed from 0 to 10

We get an aerodynamic force when air approaches what is usually the outer face of the flag, but not the inner face. Strange physics, but consistent with the numbers in partDatabase.cfg that show the +Z face having some area, −Z face zero area.

If anyone wants to remove the effect right now, we can with a Module-Manager Patch

@PART[flag*] {
    %DRAG_CUBE {
     cube = default, 0,0,0, 0,0,0, 0,0,0, 0,0,0, 0,0,0, 0,0,0, 0,0,0, 0,0,0
}}

Or, maybe exploit it for this challenge https://forum.kerbalspaceprogram.com/index.php?/topic/195104-the-esa-exploit-challenge/

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