Re-entry aerodynamics and ship design

[Invader Jim]

Is there a way to know ahead of time the natural ship orientation on re-entry assuming it has no power? For instance, I know the MK1 and 2 Commmand Pods will naturally fall bottom first and that is good because that is where they have the most heat protection. However, if you attach the SC-9001 Science Jr (or other structure) to the top or bottom or sides of the pod it changes things.

Given the re-entry challenges in 1.05 it seems really important to me to know ahead of time how my ship is going to behave when it hits atmosphere. What can I do to make sure the heat shield I slap on the bottom is actually going to serve its function and the ship is not going to turn sideways or flip 180 and go nose first? I know an engine makes a great heatshield but I want to know ahead of time that I am not going to flip and burn.

Edited November 12, 2015 by Invader Jim

[Muskrat]

Generally, you want the center of mass of the return vehicle to be as close to the heat shield as possible. The closer to center it is, the more "flip able" it will be, tending to tumble. If it is above center it will tend to want to go nose first.

Drag will also impact it, just like a rocket heading too space, but generally speaking you're not adding drag features for rentry purposes.

[Randazzo]

If you have a simple design which does not rely on fins or any control surfaces (like capsules), then it will fall heavy-end forward through the atmosphere. If your Center of Mass is too near the center of your craft, it may tumble unless you create sufficient drag on one end or another.

Of course if you hit the atmosphere while spinning wildly out of control you might die before any of this comes into play.