Bearing in mind this post has now come to a different newsgroup, apologies
if I'm going over old ground here.

Is this a separate unpressurised module then. Seems a very inconvenient
way to use such a device to me.
The question is I guess, is this kind of artificial gravity perceived by the
body as real. I thought to be of any use, the human would need to be
standing and moving, and this of course would mean a gravity gradient from
head to toe. I don't see how lying down would prove anything, as bedrest is
used to simulate long duration missions after all.

Brian

--
Brian Gaff -
Note:- In order to reduce spam, any email without 'Brian Gaff'
in the display name may be lost.
Blind user, so no pictures please!
"David Spain" wrote in message
...
[From the thread "Nautilus-X" started on sci.space.policy. In the thread
replies Pat and I got into discussion of Mark Holderman's proposal for a
ring centrifuge to be installed on the ISS as a lab for artificial gravity
experiments.

A URL for the Nautilus-X proposal and the ISS Centrifuge Demo:

http://www.spaceref.com/news/viewsr.html?pid=36068

I was curious as to the 50in Inner Diameter cross-section choice, this is
Mark's reply]

Pat Flannery wrote:
David Spain wrote:
[From the thread Nautilus-X]
A 50in cross-section ID means you need an EVA suited astronaut that
that
can't
be taller than 4ft 2in tall to stand up straight in this. Maybe the
expectation is that with it being an inflatable, the walls will stretch
to accommodate?

It doesn't look like that from the drawings; it looks like you climb
down a tube from the centrifuge axis and lie down inside the ring, like
it's a sleeping area.
So why make it so small in diameter, and why does it need to be a
complete ring? Two counterbalanced crew modules would work as well and
you wouldn't be crawling over other sleeping astronauts as you went to
and from your bed.
In fact, the way to design it would be as two discs at the end of the
entry tubes that were set with their floors towards the outside of the
rotation axis; you would come down a ladder to the center of the disc,
and the beds would be arranged like pie slices around you.

I don't know, I'm confused by this spec, but tend to
agree with you Pat, this doesn't look big enough to stand up in, only
stretch out across. But this spec is also for the wheel proposed to be
attached to the ISS for artificial gravity study, not a part of a
permanent habitat, so maybe that's the reason for the small size?

If it can't be used for transporting people on a finished ship, there's
no reason to ever mount it on anything other than the ISS...yet here
it's shown on a ship that has a clearly noted command section at the
front end.


Today I received an elaboration from Mark which he graciously agreed to
share with us here on sci.space.policy; (misspellings I corrected in "[[
... ]]")

Mark, if you read this, thanks again for answering!

/quote

Hello David,

The purpose of the ISS Centrifuge DEMO was a pure [[engineering]]
pathfinder; this type of human-mechanism has never been deployed in space.
The old Hughes Aircraft Spinner satellites were the closest embodiment of
"centrifuge/gyro" type of engineering [Intelsat-VI was actually retrieved
by an Orbiter Mission]. But you asked about the cross-section dimension.
In space, 50in is actually quite a reasonably large dimension; check out
the dimension(s) of the internal ISS integration ports. The astronaut will
reside in a supine position that allows for viewing down the transition
tunnel, and the ability of seeing the other astronaut in the zero-g hub of
the centrifuge. The 50in allows just enough room for [[maneuvering]] while
in an EVA suit, which is what the first DEMO start-ups would require
[safety]. This will truly be an unknown outcome event, both from a
physiological response of the astronaut, and the effect on the GN&C/CMGs
of the ISS. A very s-l-o-w start-up of RPM will be part of the DTO. The
astronaut will not actually "feel" any sense of the partial artificial
gravity until towards the experiment timetable. The first aspect of the
DTO is primarily for characterization of effects of the Centrifuge on the
well characterized ISS GN&C system, and to assess the integrity of the
deployed Centrifuge hardware.

However, packaging and weight were the primary drivers for the
cross-section dimension. The goal was to fit the old Orbiter External
Airlock+Centrifuge Hub+External Dynamic Ring Flywheel+Transition
Tunnel+Drive Mechanism+Deployment Hardware+Centrifuge Material&Hoberman
Ring in a Delta II Launch Vehicle [although the current trend is to now
site a Falcon-9 LV]. The price for the centrifuge, with some reasonable
program margin was under $140M [plus cost of launch]. The costs were very
conservative and realistic, and did not utilize the Voodoo cost estimator
software that NASA "officially" uses to achieve 100%
over-runs.....(chuckle).
[see James Webb Telescope costs....].

I hope this helps some; just simple Systems Engineering, with a slight
dash of creativity.

Regards,
--- Mark L. Holderman

/endquote