Dual Use? Gyromouse?( Segway Parts)

In sci.space.policy Craig Fink wrote:
On Sun, 23 Jul 2006 21:25:12 +0000, Ian Stirling wrote:

In sci.space.station Craig Fink wrote:

What is the meaning of "Duel Use"?

I would think all the mice running around the space station are gyromice?

* Pick it up and it moves the the pointer on the closest screen.

* Set it down and it's data is available for Navigation to determine
attitude (position,rates,acceleration)
snip
What kind of redundancy (2*Number_of_Mice/3) would that give you?

Almost irrelevant.
The gyros in these things are horribly noisy.

You mean the curse jumps all over the screen?

No.
I mean that - apart from the fact that they will probably clip low rates
in hardware to zero - the gyros and accellerometers in them work well at
the sorts of rates that are used in positioning - waving it around in
the air.

But, they use gyroscopes internally that get rapidly more noisy, as you
go down in rotational frequency, becoming almost useless for something
like ISS.

I suspect that ISS may almost fly apart before you get reasonable
outputs on the gyro that are distinguishable from noise.

On Thu, 27 Jul 2006 17:37:08 +0000, Ian Stirling wrote:

In sci.space.policy Craig Fink wrote:
On Sun, 23 Jul 2006 21:25:12 +0000, Ian Stirling wrote:

In sci.space.station Craig Fink wrote:

What is the meaning of "Duel Use"?

I would think all the mice running around the space station are
gyromice?

* Pick it up and it moves the the pointer on the closest screen.

* Set it down and it's data is available for Navigation to determine
attitude (position,rates,acceleration)
snip
What kind of redundancy (2*Number_of_Mice/3) would that give you?

Almost irrelevant.
The gyros in these things are horribly noisy.

You mean the cursors jumps all over the screen?

No.
I mean that - apart from the fact that they will probably clip low rates
in hardware to zero - the gyros and accelerometers in them work well at
the sorts of rates that are used in positioning - waving it around in
the air.
But, they use gyroscopes internally that get rapidly more noisy, as you
go down in rotational frequency, becoming almost useless for something
like ISS.
I suspect that ISS may almost fly apart before you get reasonable
outputs on the gyro that are distinguishable from noise.

Software? The hardware was is 32 bit (LSB). I realize most computers these
days have 64 bit hardware, but 32 bit software is fine for many people who
don't want to bother with upgrade their operating systems. Although,
Sixty-four bit hardware would be better. Filtering the noise for slow
rotating mice, like fine pointing of a cursors to select something would
be fine, wouldn't it? I haven't had to rotate the mouse wildly, shaking it
in my hand to move the cursor. I wonder how many of those LSBits are noise?

I would think, that if a middle ISS module failed (flew apart), a bunch of
dizzy mice would be a good thing for both Space Stations.

One space station into two,
http://en.wikipedia.org/wiki/Asexual_reproduction or,
http://en.wikipedia.org/wiki/Sexual_reproduction a mating of Russian space
station with United Statesian space station producing offspring. Hummm, I
feel some satire heading this way....

--
Craig Fink
Courtesy E-Mail Welcome @

In sci.space.policy Craig Fink wrote:
On Thu, 27 Jul 2006 17:37:08 +0000, Ian Stirling wrote:

In sci.space.policy Craig Fink wrote:
On Sun, 23 Jul 2006 21:25:12 +0000, Ian Stirling wrote:

In sci.space.station Craig Fink wrote:

What is the meaning of "Duel Use"?

I would think all the mice running around the space station are
gyromice?

* Pick it up and it moves the the pointer on the closest screen.

* Set it down and it's data is available for Navigation to determine
attitude (position,rates,acceleration)
snip
What kind of redundancy (2*Number_of_Mice/3) would that give you?

Almost irrelevant.
The gyros in these things are horribly noisy.

You mean the cursors jumps all over the screen?

No.
I mean that - apart from the fact that they will probably clip low rates
in hardware to zero - the gyros and accelerometers in them work well at
the sorts of rates that are used in positioning - waving it around in
the air.
snip
Software? The hardware was is 32 bit (LSB). I realize most computers these
days have 64 bit hardware, but 32 bit software is fine for many people who
don't want to bother with upgrade their operating systems. Although,

The 4 or 8 bit microcontroller in the mice running it.
I would expect them to clip low rates - say under a 1 degree a second -
to zero.
As this is usually drift in the gyros, and not a real effect, but would
lead to the cursor slowly moving if it was reported to the computer.

I would think, that if a middle ISS module failed (flew apart), a bunch of
dizzy mice would be a good thing for both Space Stations.

One space station into two,
http://en.wikipedia.org/wiki/Asexual_reproduction or,
http://en.wikipedia.org/wiki/Sexual_reproduction a mating of Russian space
station with United Statesian space station producing offspring. Hummm, I
feel some satire heading this way....


Or, not. But it does make me wonder about the design requirements of the
Space Station. Did the astronauts survive?

If you look at the development of Ocean going vessels, at some point
sinking became a real problem and water tight bulkheads were added. In the
movies, large atmospheric leaks cause automatic door to slowly close. But
the movies are wrong in this respect. Water leaks are generally much much
slower, than atmospheric leaks. How long would it take the atmospheric
pressure to drop to 3 psi at one end of the Space Station with a 15 foot
hole in the other? So an air tight bulkhead, even an automatic one, needs
to close much quicker. There probably isn't anything quicker than having
the door shut itself, blown by the wind.

Were these old concepts incorporated into the Space Station, or is that
the job of a review board? To incorporated old tried and true safety
concepts.

What was the design requirement for all the hatches between each module?
Was it a static design point, simply hold the pressure of the air behind
it when closed? Or, a dynamic design point, to slam shut driven by the
huge airflow caused by a massive structural failure of one model.

The dynamic design point would have to be stronger. In addition to holding
the pressure air, it has to stop the additional mass of the fast swinging
door and the apparent mass of all the moving air behind it. Or, include a
shock absorber in the hatch latch, to absorb the shock of a fast swinging
door.

As a space station gets larger and larger, the probability of a failure
in one of the many modules goes up too. So, a door that closes
automatically becomes more and more important. Are there any automatic
doors on the Space Station, that keep themselves partially closed, ready
to be blown closed by the wind? I would think it would be easy to design
an automatic door that remains 90% closed and automatically opens fully
when an astronaut approaches. Like at the grocery store.

Were any of these considerations taken into account in the Space Stations
design?

--
Craig Fink
Courtesy E-Mail Welcome @

Craig Fink wrote:
slower, than atmospheric leaks. How long would it take the atmospheric
pressure to drop to 3 psi at one end of the Space Station with a 15 foot
hole in the other?

There are actually a number of data points available. Most notably the
Progress vehicle crashing into Mir. And that gave the crew quite a bit
of time (minutes, not seconds). And it underlined the need for having a
hatch that is unencumbered with wires, ducts that have to be removed to
close the hatch. It wasn't a 15 foot gash.

To this end, the US side CBM is "perfect" since there are no wires,
ducts, cables that go through the hatch, so the hatches can be closed at
any time. I think on the russian side, they vastly improved their design
in terms of cabling, but there is still an air duct that must be removed
prior to hatch closure.



Were these old concepts incorporated into the Space Station, or is that
the job of a review board? To incorporated old tried and true safety
concepts.

None of the doors are automatic on the station. NASA didn't want to
hire Gene Rodenberry as creative consultant :-(

The CBM doors could conceivably be motorised with some pulley moving the
door down, and air pressure differential then pushing the door against
the seals until crews would lock it tight.


One thing to remember is that a large puncture in the pressure hull
wouldn't evacuate air "instantly" because all the equipment racks would
provide some resistance for air to flow between cabin and hole in the
pressure hull.

As a space station gets larger and larger, the probability of a failure
in one of the many modules goes up too. So, a door that closes
automatically becomes more and more important.

This is a double edge sword. You don't want to strand a crewmember on
the depressurizing side of the station.

In the ships, those automatic bulkheads still allowed crews down below
to climb to the top of the ship. Those bulkheads prevented water from
spreading horizontally. But on a station, close a hatch and people on
the damaged side cannot get to safety.

In sci.space.policy John Doe wrote:
Craig Fink wrote:
slower, than atmospheric leaks. How long would it take the atmospheric
pressure to drop to 3 psi at one end of the Space Station with a 15 foot
hole in the other?

There are actually a number of data points available. Most notably the
Progress vehicle crashing into Mir. And that gave the crew quite a bit
of time (minutes, not seconds). And it underlined the need for having a
hatch that is unencumbered with wires, ducts that have to be removed to
close the hatch. It wasn't a 15 foot gash.

To strictly answer the question - punch a hole in something in a
pressure vessel in vacuum, and the gas comes out at more or less the
speed of sound.
So - as a ballpark - with a meter square hole, you're going to get about
340m^3/s of flow out instantly.
I have no idea of the actual volume of the station - from pictures it
looks like the modules are maybe 15*4m - or maybe 150m^3... though a
quick google says total habitable volume is 425 cubic meters.

So, basically, with that size of hole, the air is gone before they have
any time to do anything about it.
A 30cm dia hole is probably at the very high end of reasonable reaction
time.
3cm, and you've got over a minute to deal with it.
3mm, and you can spend a few minutes in the module seeing if you can
localise the leak, before evacuating.

Craig Fink wrote:
slower, than atmospheric leaks. How long would it take the atmospheric
pressure to drop to 3 psi at one end of the Space Station with a 15
foot hole in the other?

With the airflow going supersonic into a large nozzle (15 ft diameter),
the end module.

There are actually a number of data points available. Most notably the
Progress vehicle crashing into Mir. And that gave the crew quite a bit
of time (minutes, not seconds). And it underlined the need for having a
hatch that is unencumbered with wires, ducts that have to be removed to
close the hatch. It wasn't a 15 foot gash.

To this end, the US side CBM is "perfect" since there are no wires,
ducts, cables that go through the hatch, so the hatches can be closed at
any time. I think on the Russian side, they vastly improved their design
in terms of cabling, but there is still an air duct that must be removed
prior to hatch closure.

I wouldn't say “perfect”. I think it would be “better” watching
(on NASA TV) the Astronaut floating towards the partially open hatches,
and the hatches silently open to let him pass through to the next module,
then closes

Were these old concepts incorporated into the Space Station, or is that
the job of a review board? To incorporated old tried and true safety
concepts.

None of the doors are automatic on the station. NASA didn't want to
hire Gene Roddenberry as creative consultant :-(

Who did they consult?

The CBM doors could conceivably be motorized with some pulley moving the
door down, and air pressure differential then pushing the door against
the seals until crews would lock it tight.

One thing to remember is that a large puncture in the pressure hull
wouldn't evacuate air "instantly" because all the equipment racks would
provide some resistance for air to flow between cabin and hole in the
pressure hull.

You did see the thread on the extra large hatches on the Space Station.
The equipment racks can even fit. These that would be the restriction that
causes the airflow to go supersonic.

As a space station gets larger and larger, the probability of a failure
in one of the many modules goes up too. So, a door that closes
automatically becomes more and more important.

This is a double edge sword. You don't want to strand a crew member on
the depressurizing side of the station.

In the ships, those automatic bulkheads still allowed crews down below
to climb to the top of the ship. Those bulkheads prevented water from
spreading horizontally. But on a station, close a hatch and people on
the damaged side cannot get to safety.

I agree, don't strand crew members in depressurized modules. On ships it's
happened before.

Is there a pressurized closet in each module, where the life preservers
(pressurized suits) are stored and donned? A minimal pressurized suit in
space would be the equivalent of a personal flotation device on the water.

In a "Space Hotel" that would be your bathroom/closet in your cabin,
wouldn't it.

Hey, Mr. Bigelow, do the cabins come with pressurized bathrooms, windows?

--
Craig Fink
Courtesy E-Mail Welcome @

On Sun, 30 Jul 2006 22:19:31 +0000, Ian Stirling wrote:

In sci.space.policy John Doe wrote:
Craig Fink wrote:
slower, than atmospheric leaks. How long would it take the atmospheric
pressure to drop to 3 psi at one end of the Space Station with a 15 foot
hole in the other?

There are actually a number of data points available. Most notably the
Progress vehicle crashing into Mir. And that gave the crew quite a bit
of time (minutes, not seconds). And it underlined the need for having a
hatch that is unencumbered with wires, ducts that have to be removed to
close the hatch. It wasn't a 15 foot gash.

To strictly answer the question - punch a hole in something in a
pressure vessel in vacuum, and the gas comes out at more or less the
speed of sound.
So - as a ballpark - with a meter square hole, you're going to get about
340m^3/s of flow out instantly.
I have no idea of the actual volume of the station - from pictures it
looks like the modules are maybe 15*4m - or maybe 150m^3... though a
quick google says total habitable volume is 425 cubic meters.

So, basically, with that size of hole, the air is gone before they have
any time to do anything about it.

Other, than watch the door slam shut blown by a strong breeze heading
towards hard vacuum.

A 30cm dia hole is probably at the very high end of reasonable reaction
time.
3cm, and you've got over a minute to deal with it.
3mm, and you can spend a few minutes in the module seeing if you can
localise the leak, before evacuating.


--
Craig Fink
Courtesy E-Mail Welcome @

On Sun, 30 Jul 2006 22:59:27 +0000, Craig Fink wrote:

On Sun, 30 Jul 2006 22:19:31 +0000, Ian Stirling wrote:
A 30cm dia hole is probably at the very high end of reasonable reaction
time.

A 50cm balloon driven by a strong breeze heading towards hard vacuum. Man,
I hope that balloon gets stuck in the hole.

3cm, and you've got over a minute to deal with it.

A 10cm balloon driven by a moderate breeze heading torard hard vacuum.
Where is that leak?

3mm, and you can spend a few minutes in the module seeing if you can

A very large noise emanating from behind some structure lining the wall of
the module? Oops.

--
Craig Fink
Courtesy E-Mail Welcome @

JRS: In article , dated Mon,
31 Jul 2006 00:01:40 remote, seen in news:sci.space.policy, Craig Fink
posted :
On Sun, 30 Jul 2006 22:59:27 +0000, Craig Fink wrote:

On Sun, 30 Jul 2006 22:19:31 +0000, Ian Stirling wrote:
A 30cm dia hole is probably at the very high end of reasonable reaction
time.

A 50cm balloon driven by a strong breeze heading towards hard vacuum. Man,
I hope that balloon gets stuck in the hole.

Atmospheric pressure is close to 1 kgf/cm^2; so, approximating pi by 3,
the balloon will need to sustain around 700 kgf, well over half of
whatever a US ton might be, while being supported by a possibly
irregular and/or sharpish edge.

I'm nor sure that even an FA-approved football would stand it.

--
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