Small parts drag (massless parts ?)

[Warzouz]

I've noticed that the small RCS part doesn't seem to generate drag. I need RCS so I added them even though they could add drag. But I would like to add some lights to my plane.

I tested it and there is no drag out of those parts (lights, RCS...)

But maybe the drag is added to the parent part (as the mass seems to do now) ?

Do (previously-)massless parts generate drag ? How to evaluate it ? Is it significant ?

[n0xiety]

The tests for this has been done and yes they add a really visible ammount of drag. It doesn't show the drag if you use the f12 interface but its there allright. Even struts are adding quite alot of drag. I couldn't find the test thread but you can try it for yourself by creating a small rocket and adding a strut to the first rocket, while adding a small part that would weight the same as strut but still aerodynamically protected behind another part to the other rocket then launching them together.

Edit: Found the test for you here you go mate;

https://www.reddit.com/r/KerbalSpaceProgram/comments/370czg/psa_struts_create_insane_amounts_of_drag/

Edited May 31, 2015 by n0xiety

[Claw]

Yes, parts that are marked via the part.cfg file as "physicsless" have their drag added to the parent part. This was done (partially) to allow for smaller parts, such as ladders and science bits, to be added without messing up the aero balance of smaller craft.

There's also an option in the debug menu to apply the drag at the part itself, instead of at the parent part. Although I don't believe that this option stays persistent when restarting KSP.

Cheers,

~Claw

[Warzouz]

thx, i'll test it.

[KerbMav]

So if I have a payload built between both a bigger tank below and nose cone above, the nose cone will become more draggy if I put in struts starting from the cone down to the tank, even if I then encase payloads and struts in a fairing.