Wrong centre of mass

[Angezerus]

This image explains everything:

I noticed this months ago, that every build I made looks just weid because I have to place the wings too much in the front to make it flyable and after some investigation, it turned out that I was right... The centre of mass is not calculated correctly. It should be somewhere around where I marked it. I use only stock parts and clearly the back should be heavier.
Parts: Turbojet, precooler /w 40 fuel, structural fuselage, mk1 inline cockpit

[Rocket In My Pocket]

Jet engine's center of mass is always further behind them than it should be, this is to account for the actual engine bits we aren't seeing which are presumably tucked away inside your craft.

Here's an example of what I'm talking about:

 Vs.

This would be what's pushing your center of mass back towards your command pod. This is a "feature" not a "bug."

However this effect can be used for fun and profit, like turning a jet engine upside down and placing it on a rover to push the center of mass below the ground making it extremely stable.

Edited July 2, 2016 by Rocket In My Pocket

[kcs123]

^^^^ This.

CoM for jet engines are out of visible engine model, for game purposes (minimize visual part representation to gain some FPS performance).
It would be inpractical to have large engine model like Rocket in my Pocket showed on picture in lego a like model pieces that we have in KSP.
Nice pictures for comparison, btw.

[FullMetalMachinist]

6 minutes ago, kcs123 said:

^^^^ This.

CoM for jet engines are out of visible engine model, for game purposes (minimize visual part representation to gain some FPS performance).
It would be inpractical to have large engine model like Rocket in my Pocket showed on picture in lego a like model pieces that we have in KSP.
Nice pictures for comparison, btw.

Well, not quite impractical to model the longer engine bits. In fact, Squad tried to do just that when 1.0.5 came out but there was a huge push back from some of the community who didn't like it, so it was taken out right before release. 

 

[kcs123]

Missed that debate. I'm in divided opinion should they use longer engine model or just nozle like it is. Both have pros/cons and like it was mentioned in that thread, VTOL crafts designs would be suffered with stock engine parts, but time will tell, will they include that or not in future releases.

[sal_vager]

VTOL's can work quite well actually, if you take advantage of the thrust reversers you can keep your CoM below the craft