Power situation in the ISS Russian Segment has degraded

(Hallerb) generated the following, unsubstantiated
drivel:


Nonsense. There are 4 large flywheels operating on the ISS
right now, the CMGs (control moment gyros).

Yeah but were talking of much bigger more powerful ones who speed
will vary a lot over time, putting and taking power as needed.

You can add so much stuff like this that research will be
impossible...

And your sources? References?


RK cited a reference for a system specifically designed for the
ISS. From the summary:

... a two-flywheel system can replace one of the nickel-hydrogen
battery strings in the ISS power system. The development unit,
sized at approximately one-eighth the size needed for ISS was run
at 60,000 rpm. The design point for the flight unit is a larger
composite flywheel, approximately 17 in. long and 13 in. in
diameter, running at 53,000 rpm when fully charged. A single
flywheel system stores 2.8 kW-hr of useable energy, enough to
light a 100-W light bulb for over 24 hr. When housed in an ISS
orbital replacement unit, the flywheel would provide energy
storage with approximately 3 times the service life of the
nickel-hydrogen battery currently in use.


Doing a bit of Googling turned up many references. Flywheel energy
storage for spacecraft has been considered at least for two or three
decades.

From NASA/TP-2003-212178 "Dynamics and Control of Attitude, Power,
and Momentum for a Spacecraft Using Flywheels and Control Moment
Gyroscopes":

Flywheels offer great promise for reducing the mass and extending
the life of spacecraft; they store more energy per unit of mass
and last significantly longer than chemical batteries. Moreover,
flywheels can simultaneously store energy and exert torque on a
spacecraft, making it possible for one system of flywheels to
replace two separate systems typically used for energy storage and
attitude control. When the mass of the two conventional systems is
taken into account, the specific energy of flywheel systems is
expected to be 5 to 10 times greater, according to Ref. [1]. The
attitude control system typically represents 11% of the mass of a
spacecraft, and batteries make up 6% of the mass; replacing 17% of
a spacecraft's mass with a flywheel system whose mass is 1.7%
would lead to a 15% reduction in total spacecraft mass. Secondary
benefits occur as well; since flywheels have higher system level
efficiencies than batteries, a reduction in solar array size and
mass becomes possible, and reboost propellant can be reduced
because the smaller arrays produce less drag. Flywheel systems are
expected to last 15 years (Ref. [1]) or more whereas typical
batteries last only 5 years. The greatest advantage of flywheels
over batteries accrues in low earth orbit where eclipse happens
more frequently and for larger fractions of an orbit than in
higher orbits; repeated charge and discharge cycles, and high
depth of discharge significantly degrade batteries over time.

--
Manfred Bartz

And your sources? References

Hey ANY movement for microgravity research is bad news, even the crew moving
around.

Microgravity research should be done on a free flyer.

http://www.grc.nasa.gov/WWW/RT2001/6...0tyburski.html

I do admit I am surprised at how far they got on this. But I stand by my
statement any extra vibration degrades microgravity research.

Of course just how much actual research is really occuring?

(Hallerb) writes:

You cant build pwer supplying flywheels into ISS. Such large ones
would cause too much vibration. Heck its even a issue with the
treadmill.

I don't hink you have any idea what you're talking about.

Jeff
--
Remove "no" and "spam" from email address to reply.
If it says "This is not spam!", it's surely a lie.

rk writes:

Flywheel Energy Storage System Designed for the International Space
Station

http://www.grc.nasa.gov/WWW/RT2001/6...0tyburski.html

Don't tell Bob, you might shatter his delusion and send him over the
edge.

Jeff
--
Remove "no" and "spam" from email address to reply.
If it says "This is not spam!", it's surely a lie.

The greatest advantage of flywheels
over batteries accrues in low earth orbit where eclipse happens
more frequently and for larger fractions of an orbit than in
higher orbits; repeated charge and discharge cycles, and high
depth of discharge significantly degrade batteries over time.

Sounds like ISS, doesn't it?

Jeff
--
Remove "no" and "spam" from email address to reply.
If it says "This is not spam!", it's surely a lie.

(Hallerb) writes:

Hey ANY movement for microgravity research is bad news, even the crew moving
around.

Microgravity research should be done on a free flyer.

That's it, dodge again, never admitting that you're wrong about energy
storage using flywheels.

Why don't you look at how Hubble does attitude control. That's an
application where you can't tolerate any vibration, yet...

http://nssdc.gsfc.nasa.gov/database/...g?sc=1990-037B

I quote:

HST used an elaborate scheme for attitude control to improve the
stability of the spacecraft during observations. Maneuvering was
performed by four of six gyros, or reaction wheels.

So, you're claiming that the "vibration problem" caused by gyros is so
bad that they shouldn't be on space stations doing microgravity
research, yet they're clearly "good enough" that you can use them on
Hubble without screwing up long exposure pictures?

Jeff
--
Remove "no" and "spam" from email address to reply.
If it says "This is not spam!", it's surely a lie.

"Hallerb" wrote in message
...

And your sources? References

Hey ANY movement for microgravity research is bad news, even the crew
moving
around.

Microgravity research should be done on a free flyer.

You know, people would take you a little more seriously if you admitted an
error instead of getting shriller about this issue.

In news:Rick C typed:
"Hallerb" wrote in message
...

And your sources? References

Hey ANY movement for microgravity research is bad news, even the
crew moving around.

Microgravity research should be done on a free flyer.

You know, people would take you a little more seriously if you
admitted an error instead of getting shriller about this issue.

He acts more the troll day after day. And he's a coward when it
comes to confronting issues. Bob, not everything you read in the press
is completely accurate.
--
Mike
__________________________________________________ ______
"Colorado Ski Country, USA" Come often, Ski hard,
Spend *lots* of money, Then leave as quickly as you can.

Manfred Bartz wrote in message ...
rk wrote:

Manfred Bartz wrote:

I am thinking flywheels. Spin them up when you have excess energy
and used them to generate power when you need it. ...

Flywheel Energy Storage System Designed for the International Space
Station

http://www.grc.nasa.gov/WWW/RT2001/6...0tyburski.html

Thanks for this reference.

I had no idea how far those systems are along the development path.
Looks like a real possibility that flywheel systems might be flown
as battery replacements in the next decade.

With some more searching I found the NASA article TP-2003-212178
"Dynamics and Control of Attitude, Power, and Momentum for a
Spacecraft Using Flywheels and Control Moment Gyroscopes". It
suggests that combining flywheel energy storage with attitude
control will have even greater benefits.

The link to the original PDF does not work for me from Australia
(it seems that I can't look up certain hosts in the .gov domain
from here), but it might be ok for traffic originating from the US:

http://techreports.larc.nasa.gov/ltr...3-tp212178.pdf

http://techreports.larc.nasa.gov/ltr...09vol1rev1.pdf
http://techreports.larc.nasa.gov/ltr...09vol2rev1.pdf

These two documents contain NASA studies about possible enhancements
to the ISS. Vol 2 have a chapter dedicated to Flywheels. It seems that
both the study referred by RK and this one in vol 2 are the same.

Anyway, everybody is free to take its own conclusions.

---

Eduardo Tesheiner
Madrid - Spain