Re: Ares


"Herb Schaltegger" <herb.schaltegger@xxxxxxxxxxxxxxxxx> wrote in message
news:0001HW.C26F64D200592FBEB019F94F@xxxxxxxxxxxxxxxxxxxx
On Tue, 15 May 2007 13:02:20 -0500, Derek Lyons wrote
(in article <464af3cf.189724281@xxxxxxxxxxxxxxxxxx>):
The conclusion does not follow from the premise Jeff. What you are
missing is _why_ the earlier system was scrapped. (I don't know
either.)

I do - mass and development cost (which trickles down to every single
subsystem). The gains in efficiency from high-frequency AC didn't
outweigh
the development costs of designing everything to run on it rather than
aerospace-standard 28V DC, or the hugh efficiency losses and mass-hits
which
would be incurred by providing a bunch of power-conditioning equipment to
step everything down to aerospace-standard specs.

Those are some of the gory details that I remember reading about. The early
research focus seemed to be on how much mass you'd save in cabling for the
power distribution system, but when the focus started to shift to early
design work for the entire system, all of the "boxes" needed to convert back
to 28V DC to actually *use* the power started to look problematic. In other
words, the overall *system* design wasn't a net win, so it was scrapped. I
was following this research program because, at the time, the EE department
at Purdue was doing some of the research and I was an Aerospace Engineering
student at Purdue at the time.

By no means was this the only area that money was wasted on the SSF program.
When that program started up, scientists proposed a lot of research that SSF
would "need" just to build the thing. I think it was a budgetary disaster
to account for all of this research as part of the SSF program since it
helped to make the program look a lot more bloated to the outside world than
it should have looked.

It's my opinion that when you're building something like ISS or the new
exploration program, you should use as much existing technology as possible.
Leave research to be done *on* ISS or *on* the moon. If you really think
you need to push crewed vehicle technology or launch vehicle technology,
then do that via X-vehicles and small test programs like Bigelow Aerospace
is doing with inflatable technology. Once that technology is proven, only
then should you incorporate it into larger programs.

Jeff
--
"They that can give up essential liberty to obtain a
little temporary safety deserve neither liberty nor
safety"
- B. Franklin, Bartlett's Familiar Quotations (1919)


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