On Sun, Feb 14, 2016 at 09:45:04PM +0100, Knapp wrote:
> Are there any engineers here that can say one way or the other what
> would happen if you set a Tigress down lightly on the Earth, say
> even in a small lake or other structure that might support it a
> little bit?

The overall structure should be perfectly fine.  It is designed to
support internal stresses from its manuevering thrusters up to 6g, and
has decent enough agility that it must have a lot of lateral bracing
as well.

The mass of the armour is a decent fraction of the mass of the whole
ship, so it must be very strongly braced just to remain intact under
such maneuvers.  One should expect at least a factor of 3 in design
stress vs expected conditions, so it should be capable of supporting
its own mass under something like 18 gee accelerations.

However, the entire weight of the ship acting through a small portion
of the area would probably be enough to crumple that area.  The
question is whether the ground would squish first - and a quick BotE
check suggests that many surfaces would.  Certainly most types of
structures on the hull in the contact area would be crushed, and there
may be some localized deformation and damage in the bottom percent or
two of the ship's volume.

Landing in an alluvial plain or other area with a fairly thick layer
of relatively soft ground would probably result in the ship sinking a
few metres -- until the contact area was sufficient to reduce the
ground pressure.  The contact area at that time would be on the order
of 50 metres aross.  Over subsequent years the ship would slowly
subside further, probably up to about 20-30 metres unless prevented by
reaching more solid rock.

If the ship was in condition to do densitometry scans, it could
probably find a suitable site to reduce damage while preventing too
much subsidence.

Landing on a hard rock surface (or a place with hard rock just a metre
or two below the surface) would be a worse proposition.  Unless the
hull were *very* much stiffer than necessary for ordinary operation,
the lower few metres would definitely crumple making the lowest few
percent of the ship unusable, and with some deformations extending
higher.  Still, the vast majority of the ship would remain intact.

- Tim