Are RCS ports completely massless?

[Sinister Dexter]

I'm building a light probe with RCS. It's so light that the number of RCS ports has a noticeable effect on the mass listed in the vehicle assembly building. If I put lots of RCS ports on it, will it really have no impact on my delta V or my TWR? Is the mass listed in the vehicle assembly building unreliable for tiny craft with massless parts? Just to be clear, I'm using the stock "Place-Anywhere 7 Linear RCS Port".

To spice this up a bit I'm attaching pics of the unfinished probe. As you can see, it has the 4-way RCS thruster blocks on it now. I think it would look better with the linear ports but I'd need more of them.

Edited January 22, 2015 by Sinister Dexter

[Red Iron Crown]

Yes, RCS ports are massless and don't affect dV or TWR. You can see the full list of massless parts here: http://wiki.kerbalspaceprogram.com/wiki/Massless_Parts

Welcome aboard!

[Sinister Dexter]

Wow that was fast. Thanks!

[eddiew]

For in-VAB help with this sort of thing, you could check out Kerbal Engineer Redux. It'll show you the delta-v numbers as you build, so you can reliably know how much difference a part is going to make to your ship - if any

[Sinister Dexter]

Thanks guys!

[flashcactus]

Adding to the previous posts, figuring out if a part is massless is easy: look at the ship mass readout before and after it's attached (preferably in Kerbal engineer or MechJeb); if it doesn't change, the part is massless.

[Red Iron Crown]

Adding to the previous posts, figuring out if a part is massless is easy: look at the ship mass readout before and after it's attached (preferably in Kerbal engineer or MechJeb); if it doesn't change, the part is massless.

That works with MJ and KER, but don't use the stock mass readout for it. It adds the nominal mass of massless parts to the total.

[Pecan]

Construction point: it might just be the pictures but I don't see any monopropellant tanks on that probe. Tonnes of Xenon, but no monopropellant.

[flashcactus]

That works with MJ and KER, but don't use the stock mass readout for it. It adds the nominal mass of massless parts to the total.

I thought so too at first, but then I experimented with all the massless parts for my UL Challenge, and found out that actually the stock mass readout ignores massless parts as well.

[Rhomphaia]

I thought so too at first, but then I experimented with all the massless parts for my UL Challenge, and found out that actually the stock mass readout ignores massless parts as well.

The mass readout in flight from the info panel does ignore massless parts. The one the VAB/SPH however does not, and massless parts still count against the limit of the launchpad/runway

[flashcactus]

The mass readout in flight from the info panel does ignore massless parts. The one the VAB/SPH however does not, and massless parts still count against the limit of the launchpad/runway

Hmm, thanks for the correction!