"BradGuth" wrote in message
...
Just for a little extra topic argument sake, on behalf of rigid
composite airships:
http://www.deepoceanexpeditions.com/ships_3_2.html
“The Deep Rover 1002 submersibles have been pressure tested to 1.25
times their maximum diving depth (1,250 meters or 4,100 feet) with a
designed safety factor of four times and a theoretical crush depth of
over 4,000 metres (13,120 feet).”


A trivial design problem compared with Venusian conditions.
The pressure vessel on those submersibles would MELT
on the Venusian surface while the sulphuric acid droplets
suspended higher in the atmosphere make that a very unpleasant
environment for acryllic plastics.

At any altitude within a meaningful fraction of the Venusian
atmosphere the temperatures are high enough to fry electronics
without a powerful cooling system.. IRC the record for duration
of any package landed on the surface is around 2 hours

Keith