Why is my shuttle replica losing control on reentry even with a CoL behind CoM?

[KarateF22]

I have a space shuttle replica which launches relatively fine, but during attempts at reentry it always tries to flip tail first, instead of nose first, despite a Center of Lift which is clearly behind the Center of Mass (and yes, i accounted for potential shifting mass). This makes accurate reentry to KSP virtually impossible due to the tumbling craft causing unpredictable amounts of drag. Does anyone know why this might be happening?

Craft file [URL="http://www./download/q17h0b7qh3nymx6/Space+Shuttle+Mk+3.craft"]here[/URL], if anyone wants it for examination. Edited November 25, 2015 by KarateF22

[Venusgate]

Upper atmosphere doesn't affect lift as much as your CoM is behind the "middle" of your craft.

[KarateF22]

[quote name='Venusgate']Upper atmosphere doesn't affect lift as much as your CoM is behind the "middle" of your craft.[/QUOTE]

That didn't seem to matter before this patch, did they make drag better translate to lift or something? And if so, its odd that they didn't make it take that into account when displaying CoL.

[Frozen_Heart]

I had a thread on the same topic and am having similar problems.

Its due to the shuttle body having huge amounts of drag side on that doesn't show in the VAB. As soon as its away from prograde it will drag and then tumble. But when facing prograde it will lawn dart as the body doesn't make much drag from that angle.

[KarateF22]

Your thread on the matter answers this for me, thanks Frozen.

[HafCoJoe]

Same. Thanks. So the problem is SOM compared to drag? This is a very annoying thing if so because the large cargo bay has an insane amount of drag, and the COM is usually behind it. I may have to do some crazy stunts to pull this off then.

[Frozen_Heart]

[quote name='Avera9eJoe']Same. Thanks. So the problem is SOM compared to drag? This is a very annoying thing if so because the large cargo bay has an insane amount of drag, and the COM is usually behind it. I may have to do some crazy stunts to pull this off then.[/QUOTE]

I still haven't found a way to solve this properly. Move CoL forward and it tumbles, backwards and it lawn darts. In the middle it does both. I had a barely controllable shuttle at one point but trying to make any changes made it unflyable again.

[Val]

[COLOR=#333333]The CoL indicator does not factor in drag/body lift for non-wing parts.[/COLOR]

[COLOR=#333333]The best way around this issue is to make sure your CoM and CoL is in front of or exactly in the center of the Cargo Bay(s) when you are in re-entry configuration.

But it will most likely not look like the real shuttle, with CoM and CoL that far forward.

Recreating real life crafts is generally hard in KSP, because the mass of the parts aren't to scale.[/COLOR]

[steuben]

I talked to the one of the crew that worked on the simulator for the shuttle once. The aerodynamics of the real thing are that bad.

[KarateF22]

[quote name='Frozen_Heart']I still haven't found a way to solve this properly. Move CoL forward and it tumbles, backwards and it lawn darts. In the middle it does both. I had a barely controllable shuttle at one point but trying to make any changes made it unflyable again.[/QUOTE]

I fixed it by moving the fuel tank to behind the cockpit instead of the cargo bay. Only issue is then its actually a little bit too stable, meaning it has some issues burning off speed during reentry, but it is able to pull it off eventually if I pull up for the entirety of reentry; only downside to that is pinpointing KSC is a bit harder. Today I'm experimenting to see if air brakes at the very tail of the craft right next to the Tail Fin might help with this a bit, I'm hoping that their additional pull upwards in tandem with their straight speed bleed will be enough for the job. Edited November 25, 2015 by KarateF22