Not far in the future, judging by what Elon said this week at the
launch. BFS is a reusable orbital stage.
On 2018-02-10 09:38, John Schilling wrote:
I believe it was achievable 20 years ago, just more trouble than it
was worth. It is probably more achievable now, but may still be more
trouble than it is worth.
One useful change has been improved materials and manufacturing
techniques to reduce structural mass, which is critical for SSTO.
Friction stir welding of Al-Li, for example. And maybe LOX-compatible
composites, depending on what happens with XCOR's "Nonburnite".
Another, I think underrated, change is increased skepticism through
hard experience of shiny technologies that we probably don't need,
like air-turboscramwarp drives and tankage shaped into elaborate
aerodynamic shapes.
Operational validation of VTVL reusables is a good thing to have,
given that given that expendable SSTO is an economic non-starter. The
best answer may still involve wings (attached to cylindrical tanks!),
but demanding wings because that's how Shuttle worked and we don't
trust anything else is a needless and possibly crippling constraint.
The biggest obstacle I see remaining, is the ability to safely and
reliably recover an orbital stage without excessive TPS mass.
Unfortunately, SpaceX seems to have pushed their work on that one
farther into the future, so maybe that's one for DARPA, Blue Origin,
or some newcomer to the field.
Propulsion is, I think, not a major constraint. We've got at least
marginally reusable rockets with adequate performance. There are some
nice-to-haves we could work for on that front, but no showstoppers for
a Mark 1 SSTO.
John Schilling
john.schilling@xxxxxxxxxxxxxx
(661) 718-0955
On 2/10/2018 9:01 AM, William Claybaugh wrote:
Dr. Schilling’s comments on SSTO got me thinking about Have Region, DC-X, and X-33.
Technology is now about 20 years further down the road; is chemical rocket reusable SSTO now achievable?
What is different?
Bill