View Single Post
  #24  
Old December 26th 18, 06:45 AM posted to sci.space.policy
Fred J. McCall[_3_]
external usenet poster
 
Posts: 10,018
Default BFS drops composite construction

JF Mezei wrote on Tue, 25 Dec 2018
16:29:41 -0500:

On 2018-12-24 23:46, Fred J. McCall wrote:

Last heard, SpaceX was going to use a ceramic named TUFROC-X for TPS
on Starship. It's not possible to get that degree of thermal
protection with metal.


In that case, is there really an advantage to using stainless steel for
the skin instead of aluminium or titanium ?


Yes, there are several.


From a structural strength point of view:

BFS ~ 9m diameter.
A380 ~ 7m diameter.


Now run the load numbers. They're nowhere near the same.


Since a crewed BFS would need to support 14.7 PSI whereas an aircraft
generally supports about 8PSI, does stainless steel have more strength
ofor that diametre than would Aluminium or Titanium ?


Aluminum is too weak and melts at half the temperature of 330
stainless. Titanium has an advantage in melting point, but is
preposterously difficult to machine.


--
"Ignorance is preferable to error, and he is less remote from the
truth who believes nothing than he who believes what is wrong."
-- Thomas Jefferson