[AR] Re: DC-X anniversary
- From: Henry Spencer <hspencer@xxxxxxxxxxxxx>
- To: arocket list <arocket@xxxxxxxxxxxxx>
- Date: Sun, 19 Aug 2018 14:55:44 -0400 (EDT)
On Sun, 19 Aug 2018, James Fackert wrote:
Is SpaceX falcon 9 block 5 not the very successful child of DC-X ?
Only in a small way. Being able to reuse the first stage (say) a dozen
times with modest refurbishment -- feasibility of which is not yet fully
established for Falcon 9 block 5 -- is still a far cry from reusing the
whole vehicle with a small-ground-crew turnaround time measured in hours.
The long-term goal of the effort that produced DC-X was vehicles that
could operate at a few times fuel cost. Falcon 9 currently costs $50-60M
and Elon has stated the fuel cost as being $0.2M, so he's got a long way
to go yet. The modest reusability of Falcon 9's first stage is a useful
saving and a step in the right direction, but *not* yet a fundamental
change in space launch.
It just took a few years for faster-than-real-time modeling and predictive
control proc and sensors to make the concept practical .
Uh, DC-X showed 25 years ago that the concept was practical then, if you
design the vehicle for it from the start. For example, you want fully
throttlable engines -- unlike Falcon 9's -- so the approach doesn't have
to be too precisely timed. For another, you want a vehicle that can do
incremental flight testing -- unlike Falcon 9 -- so that you can start
with relatively easy flights and gradually work up to doing the full
operational profile, making it possible to find problems without losing a
vehicle every time. Even F9 block 5 is an expendable vehicle with a bit
of reusability kludged in, not a vehicle designed from the start to be
fully reusable; it makes a difference. (Remember that vertical landing of
the first stage was SpaceX's second try at making it partly reusable, the
first try -- splash it down intact and salvage parts from it -- having
been a total failure.)
Pioneers, they were.
Is anyone from dcx project working at SpaceX?
Not that I'm aware of, although I haven't kept track. I believe some of
the DC-X folks *are* at Blue Origin.
Henry
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