Engine/tank combo

[LawnDartLeo]

NOOB ALERT!!!

1) Is there any limitation that would prevent a combination fueltank/engine part?

2) Even is there is not, is this just a bad idea to begin with?... not like I have seen many like this before (ARM might be first).

3) If for the sake of design I want my part to have 8 sides, does my mesh model still need to conform with a 12 sided collider?

[PringleMan]

NOOB ALERT!!!

1) Is there any limitation that would prevent a combination fueltank/engine part?

2) Even is there is not, is this just a bad idea to begin with?... not like I have seen many like this before (ARM might be first).

3) If for the sake of design I want my part to have 8 sides, does my mesh model still need to conform with a 12 sided collider?

1) Not at all

2) It is not a bad idea, it is just difficult to balance it. As well, make sure that you have all of your proper transforms

3) Dunno on that one myself.

edit: The reason it is difficult to balance or relatively undesirable, is because with an LF engine you need a pretty good amount of tank in order to not just burn through it instantly. If you only have a sliver of tank, you might as well just have the engine by itself. If you have a big tank, it becomes unwieldy. And the reduction in part count probably wont really help THAT much, though I guess it depends.

But as for the basic idea of it, that is precisely what the SRBs are. They are a thrust transform with a solid fuel tank

Edited April 3, 2014 by PringleMan

[Daishi]

NOOB ALERT!!!

1) Is there any limitation that would prevent a combination fueltank/engine part?

2) Even is there is not, is this just a bad idea to begin with?... not like I have seen many like this before (ARM might be first).

3) If for the sake of design I want my part to have 8 sides, does my mesh model still need to conform with a 12 sided collider?

3) - Nah. The collider is only so you can...

Select the part in the VAB\SPH

Stop other parts from clipping with it during construction

Give other parts a surface to radially attach to

Give the physics engine dimensions to simulate around.

There is no limitation of how high poly your model can be, and how low poly your collider is. General rule of thumb though, make it as simple as possible (so KSP doesn't calculate more physics than it needs to) with enough external polys to make radial symmetry work properly. 12 sided cylinders are generally the status quo for small cylindrical tanks.

The mesh for the model is essentially a visual shell that sits on top of the invisible collider. The collider is what you interact with in game

Edited April 3, 2014 by Daishi

[NathanKell]

Many part mods include these, FYI.