just curious is there any dropships and rockets can be invisible?

Yes.
All you need is for them to not have a sprite. I'm not sure how, but it is possible to make something invisible that collides with other things... I suggest checking out the Yuurei Bushi in the Darkstorm(?) mod.

Well... not really, though. Every MOS (MovableObjectSprite) is technically required to have a sprite file. However, the Null.bmp in Base.rte is pretty commonly used since it's a blank 255-0-255 fuchsia magenta image, which translates to background/transparency in-game. IIRC, Darkstorm used a different method of achieving invisibility which included altering the Scale property of an actor's parts (Scale = 0 would make them aesthetically non-existent).

Sure, anything really can be made not-visible. It is pretty much impossible to maintain proper hitboxes, with either of the methods.

Ok soo.... it is possible to have an actor to be invisible along with HD anything they've held?
it is enough for me though