In 2018 SpaceX made the decision to use stainless steel instead of carbon fiber/epoxy materials for their Starship System with the aims of improving performance, while drastically decreasing costs.

 

Stainless steel properties:

• Very ductile, very tough. No fracture issues

• that at cryogenic temperatures, the strength is boosted by 50 percent.

• it’s obviously cheap, it’s obviously fast.

• It has a high melting point. 1600 degrees Fahrenheit.

 

Elon Musk also proposed a transpirational heat shield:

 

“You just need, essentially, [a stainless-steel sandwich]. You flow either fuel or water in between the sandwich layer, and then you have [very tiny] perforations on the outside and you essentially bleed water [or fuel] through them … to cool the windward side of the rocket.”

– SpaceX CEO Elon Musk.

 

All in all, this would appear to be a viable application for Hexaflex. 

Hexaflex can be fabricated from a continuous sheet of stainless steel that has been die cut with a repeating geometric design, creased and folded concertina style in upon itself to make a double sided core material that is flexible, able to vent, exhibits good bend and shear strength, and has a large surface bonding area rendering it suitable in the construction of lightweight sandwich panels.

 

A transpirational heat shield must be able:

• to efficiently join inner and outer shell surfaces with stringers

• to provide a clear interstitial space, allowing fluids to flow through its structure

• to be formed into compound curvatures

• to serve double duty as structure

 

Expanding on the concept of thermal protection systems,  Hexaflex panels can be arranged in multi-layers or plies in order to create storage for different gasses or  liquids.