Does changing root part affect drag?

[A35K]

So basically I've sent a spaceplane to eve, which worked fine when i hyper edited it there to test. But after bringing it on an actual mission, it now suddenly has way more drag. I used Aero debug to obtain these numbers:

During test:

Drag at 130m/s at 400m above sea level is about 300kN.

In actual mission:

Drag at same conditions is 480kN.

The 2 vessels are exactly the same, with the exception being a different root part as a decoupler was used on the actual mission (the remainderof which appears to be the root part). Even after removing this decoupler, the drag is the same, and doesn't allow the plane to go fast enough to fly. So can havinga different root part cause this? Or is it some other bug?

[Lt_Duckweed]

The only time I have seen the root part effect drag is when the root part is either a fairing or a cargo/payload bay. As long as your root part isn't one of those it's likely the issue is coming from somewhere else.

[Spricigo]

3 hours ago, A35K said:

The 2 vessels are exactly the same, with the exception being a different root part

how about struts/autostruts? Did you used it at any moment?

[AHHans]

As already mentioned: which part is the root part should not affect the drag.

So these drag values are from the extra aero data window, not the aero values in the PAW? Is the attitude of the craft the same in both cases? In particular the AoA?

It would help to have screenshots of the two situations.

[jimmymcgoochie]

Press F12 to turn on the aero forces display and look for the biggest red spike trailing behind the plane, that’s the draggy part. It can be quite hard to find them sometimes, but when you do enabling the aero/drag debug panels in the cheats menu will show how much drag it’s producing. There isn’t much you can do to fix it though unless you’re really good at persistent file editing and can remove the part (assuming it isn’t important!).

[OHara]

Just confirming that there is one case were root part matters, as @Lt_Duckweed said.  It has been a bug since the beginning of the aerodynamics from 1.05 (tracker link, maybe related). If the root part is a fairing or cargo bay, after quickload or switching craft, the game treats that fairing or bay as open.

[A35K]

Sorry for the delay, thanks everyone for the replies. Basically I just hyperedited in a copy of the same vessel which worked perfectly in the end, as nothing else worked. To answer some question, no, there were no autostruts or anything. The only difference was somehow the root part being a decoupler (which I have no idea how it happened as when I go to VAB and try to make a decoupler the root part the game won't even let me).