| Topic: |
Science > Physics |
| User: |
"George" |
| Date: |
27 Jul 2004 06:11:12 PM |
| Object: |
Are there any Space Elevator experts here? |
Sorry if this has been discussed.
Every time I read an Arther C. Clarke novel with his Space Elevator
in it, this question comes to mind, but I've never seen it
specifically analyzed.
I'm talking about the change in orbital velocity which the object
being raised or lowered must experience. At the earth's surface on
the equator, an object at the bottom of the elevator has an
orbital velocity of about 1038 mph (3693mi * 2pi / 24hrs). But by
the time this object has been raised to geosynchronous orbit
directly above that point on the equator, it's orbital velocity must
have been increased to about 6859 mph (26200mi * 2pi /24hrs).
Something has to impart the needed "sideways" acceleration to
achieve a delta-V of about 5821mph. Otherwise, the elevator cable
or shaft will bow backward (Westward) as the payload climbs the
cable, and bow forward as it climbs back down to earth.
It may be that the bowing just happens, but isn't big enough to
matter. Of course that would depend on the size of the payload
going up or down the cable, and possibly on the speed of ascent or
descent. But I just wondered if anyone can point me to a source
where this problem has really been addressed. I assume this
problem isn't a fatal flaw in the concept, but I would like to see
where someone has run the numbers to prove that.
Arthur, are you out there?
---
Remove NOnnnSPAM to reply via email.
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| User: "stan" |
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| Title: Re: Are there any Space Elevator experts here? |
27 Jul 2004 10:05:53 PM |
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"George" <gh424NO824SPAM@cox.net> wrote in message
news:tiBNc.2497$zA4.368@lakeread04...
Sorry if this has been discussed.
Every time I read an Arther C. Clarke novel with his Space Elevator
in it, this question comes to mind, but I've never seen it
specifically analyzed.
I'm talking about the change in orbital velocity which the object
being raised or lowered must experience. At the earth's surface on
the equator, an object at the bottom of the elevator has an
orbital velocity of about 1038 mph (3693mi * 2pi / 24hrs). But by
the time this object has been raised to geosynchronous orbit
directly above that point on the equator, it's orbital velocity must
have been increased to about 6859 mph (26200mi * 2pi /24hrs).
Something has to impart the needed "sideways" acceleration to
achieve a delta-V of about 5821mph. Otherwise, the elevator cable
or shaft will bow backward (Westward) as the payload climbs the
cable, and bow forward as it climbs back down to earth.
It may be that the bowing just happens, but isn't big enough to
matter. Of course that would depend on the size of the payload
going up or down the cable, and possibly on the speed of ascent or
descent. But I just wondered if anyone can point me to a source
where this problem has really been addressed. I assume this
problem isn't a fatal flaw in the concept, but I would like to see
where someone has run the numbers to prove that.
Arthur, are you out there?
---
Remove NOnnnSPAM to reply via email.
Rather than a space elevator, how about a Space Smokesack? This way all the
smoke generated on earth can be put into outterspace. You could also
install tracks on the side for a side hung elevator car to go up and down.
.
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| User: "Ian Stirling" |
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| Title: Re: Are there any Space Elevator experts here? |
27 Jul 2004 08:29:04 PM |
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George <gh424NO824SPAM@cox.net> wrote:
Sorry if this has been discussed.
Not an expert, but interested.
Every time I read an Arther C. Clarke novel with his Space Elevator
in it, this question comes to mind, but I've never seen it
specifically analyzed.
I'm talking about the change in orbital velocity which the object
being raised or lowered must experience. At the earth's surface on
the equator, an object at the bottom of the elevator has an
orbital velocity of about 1038 mph (3693mi * 2pi / 24hrs). But by
It's not actually orbital, in the classical sense, as it's kept
up by the earth.
If it was in a true orbit (neglecting the earths volume) at that velocity,
and that point in space, then it would rapidly plunge towards the center
of the earth, in an elipse some few hundred Km by 12000Km.
the time this object has been raised to geosynchronous orbit
directly above that point on the equator, it's orbital velocity must
have been increased to about 6859 mph (26200mi * 2pi /24hrs).
Something has to impart the needed "sideways" acceleration to
achieve a delta-V of about 5821mph. Otherwise, the elevator cable
or shaft will bow backward (Westward) as the payload climbs the
cable, and bow forward as it climbs back down to earth.
It may be that the bowing just happens, but isn't big enough to
matter. Of course that would depend on the size of the payload
going up or down the cable, and possibly on the speed of ascent or
descent. But I just wondered if anyone can point me to a source
where this problem has really been addressed. I assume this
problem isn't a fatal flaw in the concept, but I would like to see
where someone has run the numbers to prove that.
The numbers work.
The cable and counterweight does indeed bow east or west as the elevator
rises or falls.
This has to be taken into account, and how much depends on the tether.
For a stronger tether, it'll be more pronounced, as the weight of the cars
will be a higher fraction, if there are cars going up and down, it'll be
less, though the cable will be a stranger shape.
The faster the cars are of course, the worse this is.
Google for the thread
beanstalks (was Re: Metallic hydrogen ...)
which I think discussed this a bit.
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| User: "Uncle Al" |
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| Title: Re: Are there any Space Elevator experts here? |
27 Jul 2004 07:53:18 PM |
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George wrote:
Sorry if this has been discussed.
Every time I read an Arther C. Clarke novel with his Space Elevator
in it, this question comes to mind, but I've never seen it
specifically analyzed.
I'm talking about the change in orbital velocity which the object
being raised or lowered must experience. At the earth's surface on
the equator, an object at the bottom of the elevator has an
orbital velocity of about 1038 mph (3693mi * 2pi / 24hrs). But by
the time this object has been raised to geosynchronous orbit
directly above that point on the equator, it's orbital velocity must
have been increased to about 6859 mph (26200mi * 2pi /24hrs).
Something has to impart the needed "sideways" acceleration to
achieve a delta-V of about 5821mph. Otherwise, the elevator cable
or shaft will bow backward (Westward) as the payload climbs the
cable, and bow forward as it climbs back down to earth.
It may be that the bowing just happens, but isn't big enough to
matter. Of course that would depend on the size of the payload
going up or down the cable, and possibly on the speed of ascent or
descent. But I just wondered if anyone can point me to a source
where this problem has really been addressed. I assume this
problem isn't a fatal flaw in the concept, but I would like to see
where someone has run the numbers to prove that.
Arthur, are you out there?
It won't work. The minimum energy curve from surface to
geosynchronous orbit is not a straight line. The added tensile
stress and length dooms a construct that cannot be built because
of its tensile stress and length. It must be constructed of
dielectrics or the Earth's billowing magnetosphere will roman
candle it by induction. If it is non-conductive, what powers the
gondola up and down? A funicular is asinine - the weight. The
stretch can only propagate at the speed of sound. 24,000 miles
is hours of delay. Cable inertia alone is damning.
NASA, "we will launch the Space Scuttle 5000 times to build the
Beanstalk."
Right. Uncle Al bets 2 and out.
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf
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| User: "" |
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| Title: Re: Are there any Space Elevator experts here? |
28 Jul 2004 09:04:56 AM |
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Uncle Al <UncleAl0@hate.spam.net> wrote in message news:<4106F8FE.FC859A7@hate.spam.net>...
[snip]
It won't work. The minimum energy curve from surface to
geosynchronous orbit is not a straight line.
Hey, Al. You've said this before, and I've asked about it before,
but if you answered I never saw it. What do you base this on?
Because I don't check you.
Socks
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| User: "" |
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| Title: Ping Uncle Al (was Re: Are there any Space Elevator experts here? |
05 Aug 2004 09:01:42 AM |
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wrote in message news:<c7976c46.0407280604.7a01f8c9@posting.google.com>...
Uncle Al <UncleAl0@hate.spam.net> wrote in message news:<4106F8FE.FC859A7@hate.spam.net>...
[snip]
It won't work. The minimum energy curve from surface to
geosynchronous orbit is not a straight line.
Hey, Al. You've said this before, and I've asked about it before,
but if you answered I never saw it. What do you base this on?
Because I don't check you.
Hey, Al. I still have not seen any answer.
Socks
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| User: "Uncle Al" |
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| Title: Re: Ping Uncle Al (was Re: Are there any Space Elevator experts here? |
05 Aug 2004 09:43:25 AM |
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wrote:
wrote in message news:<c7976c46.0407280604.7a01f8c9@posting.google.com>...
Uncle Al <UncleAl0@hate.spam.net> wrote in message news:<4106F8FE.FC859A7@hate.spam.net>...
[snip]
It won't work. The minimum energy curve from surface to
geosynchronous orbit is not a straight line.
Hey, Al. You've said this before, and I've asked about it before,
but if you answered I never saw it. What do you base this on?
Because I don't check you.
Hey, Al. I still have not seen any answer.
Socks
Only the distal end is in equilibrium orbit. Orbital period at
230 miles altitude is 1.5 hours (ISS) not 24 hrs. Don't trust
me, work the numbers yourself for balancing stress and strain.
It isn't anywhere near a straight line. With the distal end in
equilibrium orbit, all the distorting forces are concentrated at
lower altitudes. It won't be straight of its own and there will
be nothing up high pulling it straight.
http://www.mazepath.com/uncleal/sunshine.jpg
Ping puppet_sock
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf
.
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| User: "" |
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| Title: Re: Ping Uncle Al (was Re: Are there any Space Elevator experts here? |
05 Aug 2004 03:29:26 PM |
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Uncle Al <UncleAl0@hate.spam.net> wrote in message news:<4112478D.503DB6EB@hate.spam.net>...
puppet_sock@hotmail.com wrote:
puppet_sock@hotmail.com wrote in message news:<c7976c46.0407280604.7a01f8c9@posting.google.com>...
Uncle Al <UncleAl0@hate.spam.net> wrote in message news:<4106F8FE.FC859A7@hate.spam.net>...
[snip]
It won't work. The minimum energy curve from surface to
geosynchronous orbit is not a straight line.
Hey, Al. You've said this before, and I've asked about it before,
but if you answered I never saw it. What do you base this on?
Because I don't check you.
Hey, Al. I still have not seen any answer.
Socks
Only the distal end is in equilibrium orbit. Orbital period at
230 miles altitude is 1.5 hours (ISS) not 24 hrs. Don't trust
me, work the numbers yourself for balancing stress and strain.
It isn't anywhere near a straight line. With the distal end in
equilibrium orbit, all the distorting forces are concentrated at
lower altitudes. It won't be straight of its own and there will
be nothing up high pulling it straight.
Um. And the orbital period at the surface of the Earth is even
shorter. But I don't see the surface of the Earth getting
smeared out relative to the top of mountains. And I don't
see any huge systematic winds pushing all in the same direction
around the Earth due to the atmosphere being quite high.
An orbital tower would be undergoing rigid rotation. There are
no sideways acting forces when it's just rotating along. No more
than there are such forces causing different depths of the
Earth to rotate relative to eachother.
There will be plenty up high pulling it straight. The typical
design for an orbital tower requires a significant counterweight
past the 24 hour orbit distance.
It would be very different if we were talking about the structure
moving up and down, or when we start considering moving loads
up and down. But hanging a cable, there's no issue beyond the
brute tensile strenght. (Which, near as I can tell, is still
massively beyond any materials we can manufacture.)
I have "run the numbers." I get a vertical straight line. Can
you explain what it is you are calculating when you get other
than a straight line?
Socks
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| User: "Ian Stirling" |
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| Title: Re: Ping Uncle Al (was Re: Are there any Space Elevator experts here? |
05 Aug 2004 10:25:53 AM |
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Uncle Al <UncleAl0@hate.spam.net> wrote:
puppet_sock@hotmail.com wrote:
puppet_sock@hotmail.com wrote in message news:<c7976c46.0407280604.7a01f8c9@posting.google.com>...
Uncle Al <UncleAl0@hate.spam.net> wrote in message news:<4106F8FE.FC859A7@hate.spam.net>...
[snip]
It won't work. The minimum energy curve from surface to
geosynchronous orbit is not a straight line.
Hey, Al. You've said this before, and I've asked about it before,
but if you answered I never saw it. What do you base this on?
Because I don't check you.
Hey, Al. I still have not seen any answer.
Socks
Only the distal end is in equilibrium orbit. Orbital period at
230 miles altitude is 1.5 hours (ISS) not 24 hrs. Don't trust
me, work the numbers yourself for balancing stress and strain.
It isn't anywhere near a straight line. With the distal end in
equilibrium orbit, all the distorting forces are concentrated at
lower altitudes. It won't be straight of its own and there will
be nothing up high pulling it straight.
I could make exactly the same argument about why it's impossible
to clamber along a loose horizontal rope.
The accelleration along the plane of the orbit comes from displacement
of the anchor backwards in its 'orbit' (the center of gravity is of
course above GEO).
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| User: "Uncle Al" |
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| Title: Re: Ping Uncle Al (was Re: Are there any Space Elevator experts here? |
05 Aug 2004 11:50:16 AM |
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Ian Stirling wrote:
Uncle Al <UncleAl0@hate.spam.net> wrote:
puppet_sock@hotmail.com wrote:
puppet_sock@hotmail.com wrote in message news:<c7976c46.0407280604.7a01f8c9@posting.google.com>...
Uncle Al <UncleAl0@hate.spam.net> wrote in message news:<4106F8FE.FC859A7@hate.spam.net>...
[snip]
It won't work. The minimum energy curve from surface to
geosynchronous orbit is not a straight line.
Hey, Al. You've said this before, and I've asked about it before,
but if you answered I never saw it. What do you base this on?
Because I don't check you.
Hey, Al. I still have not seen any answer.
Socks
Only the distal end is in equilibrium orbit. Orbital period at
230 miles altitude is 1.5 hours (ISS) not 24 hrs. Don't trust
me, work the numbers yourself for balancing stress and strain.
It isn't anywhere near a straight line. With the distal end in
equilibrium orbit, all the distorting forces are concentrated at
lower altitudes. It won't be straight of its own and there will
be nothing up high pulling it straight.
I could make exactly the same argument about why it's impossible
to clamber along a loose horizontal rope.
The accelleration along the plane of the orbit comes from displacement
of the anchor backwards in its 'orbit' (the center of gravity is of
course above GEO).
Placing the center of gravity above GEO requires a huge amount of
additional mass - that also won't be in equilibrium orbit. A
beanstalk is damned by weight vs. tensile strength. Pulling it
taut on the distal end simply snaps it.
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf
.
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| User: "Skybuck Flying" |
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| Title: Re: Ping Uncle Al (was Re: Are there any Space Elevator experts here? |
05 Aug 2004 12:45:12 PM |
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It doesn't have to be straight...
Just climb the fricking rope :D
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| User: "Uncle Al" |
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| Title: Re: Ping Uncle Al (was Re: Are there any Space Elevator experts here? |
05 Aug 2004 01:20:46 PM |
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Skybuck Flying wrote:
It doesn't have to be straight...
Just climb the fricking rope :D
It won't work. Adding a trivial 1% to the length (remember
thermal expansion, boy - it goes in and out of raw sunlight
continuously) is 2000 miles. That's a whole lot of wunga-wunga
for something, at very beast extrapolated, hard by its maximum
tensile strength
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf
.
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| User: "Dale Trynor" |
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| Title: Re: Ping Uncle Al (was Re: Are there any Space Elevator experts here? |
06 Aug 2004 12:51:29 AM |
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Uncle Al wrote:
Skybuck Flying wrote:
It doesn't have to be straight...
Just climb the fricking rope :D
It won't work. Adding a trivial 1% to the length (remember
thermal expansion, boy - it goes in and out of raw sunlight
continuously) is 2000 miles. That's a whole lot of wunga-wunga
for something, at very beast extrapolated, hard by its maximum
tensile strength
Dale Trynor wrote:
Don't know about carbon nanotubes but I do remember reading that the
thermal expansion of carbon fiber was very near zero.
Dale
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf
.
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| User: "Ian Stirling" |
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| Title: Re: Ping Uncle Al (was Re: Are there any Space Elevator experts here? |
05 Aug 2004 12:50:54 PM |
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Uncle Al <UncleAl0@hate.spam.net> wrote:
Ian Stirling wrote:
Uncle Al <UncleAl0@hate.spam.net> wrote:
puppet_sock@hotmail.com wrote:
puppet_sock@hotmail.com wrote in message news:<c7976c46.0407280604.7a01f8c9@posting.google.com>...
Uncle Al <UncleAl0@hate.spam.net> wrote in message news:<4106F8FE.FC859A7@hate.spam.net>...
[snip]
It won't work. The minimum energy curve from surface to
geosynchronous orbit is not a straight line.
Hey, Al. You've said this before, and I've asked about it before,
but if you answered I never saw it. What do you base this on?
Because I don't check you.
Hey, Al. I still have not seen any answer.
Socks
Only the distal end is in equilibrium orbit. Orbital period at
230 miles altitude is 1.5 hours (ISS) not 24 hrs. Don't trust
me, work the numbers yourself for balancing stress and strain.
It isn't anywhere near a straight line. With the distal end in
equilibrium orbit, all the distorting forces are concentrated at
lower altitudes. It won't be straight of its own and there will
be nothing up high pulling it straight.
I could make exactly the same argument about why it's impossible
to clamber along a loose horizontal rope.
The accelleration along the plane of the orbit comes from displacement
of the anchor backwards in its 'orbit' (the center of gravity is of
course above GEO).
Placing the center of gravity above GEO requires a huge amount of
additional mass - that also won't be in equilibrium orbit. A
It's slightly above GEO, not much.
The lowest payload/total mass ratio is actually gotten by simply extending
the tether.
beanstalk is damned by weight vs. tensile strength. Pulling it
taut on the distal end simply snaps it.
Given a suitable material (say 50GPa), why should it snap it?
There is tension at the base, equal to the weight of the car and a little
bit more.
Putting the car on the tether just reduces the tension on the base, and
does not impose shock loads.
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| User: "John Sefton" |
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| Title: Re: Are there any Space Elevator experts here? |
31 Jul 2004 10:49:54 AM |
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Uncle Al wrote:
George wrote:
Sorry if this has been discussed.
Every time I read an Arther C. Clarke novel with his Space Elevator
in it, this question comes to mind, but I've never seen it
specifically analyzed.
I'm talking about the change in orbital velocity which the object
being raised or lowered must experience. At the earth's surface on
the equator, an object at the bottom of the elevator has an
orbital velocity of about 1038 mph (3693mi * 2pi / 24hrs). But by
the time this object has been raised to geosynchronous orbit
directly above that point on the equator, it's orbital velocity must
have been increased to about 6859 mph (26200mi * 2pi /24hrs).
Something has to impart the needed "sideways" acceleration to
achieve a delta-V of about 5821mph. Otherwise, the elevator cable
or shaft will bow backward (Westward) as the payload climbs the
cable, and bow forward as it climbs back down to earth.
It may be that the bowing just happens, but isn't big enough to
matter. Of course that would depend on the size of the payload
going up or down the cable, and possibly on the speed of ascent or
descent. But I just wondered if anyone can point me to a source
where this problem has really been addressed. I assume this
problem isn't a fatal flaw in the concept, but I would like to see
where someone has run the numbers to prove that.
Arthur, are you out there?
It won't work. The minimum energy curve from surface to
geosynchronous orbit is not a straight line. The added tensile
stress and length dooms a construct that cannot be built because
of its tensile stress and length. It must be constructed of
dielectrics or the Earth's billowing magnetosphere will roman
candle it by induction. If it is non-conductive, what powers the
gondola up and down? A funicular is asinine - the weight. The
stretch can only propagate at the speed of sound. 24,000 miles
is hours of delay. Cable inertia alone is damning.
NASA, "we will launch the Space Scuttle 5000 times to build the
Beanstalk."
Right. Uncle Al bets 2 and out.
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf
This is one area where I agree with Al.
He can't see how stupid a BH is, but a
Space Elevator is even stupider, and
somehow he senses that.
John
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| User: "Uncle Al" |
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| Title: Re: Are there any Space Elevator experts here? |
31 Jul 2004 11:06:51 AM |
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John Sefton wrote:
Uncle Al wrote:
George wrote:
Sorry if this has been discussed.
Every time I read an Arther C. Clarke novel with his Space Elevator
in it, this question comes to mind, but I've never seen it
specifically analyzed.
I'm talking about the change in orbital velocity which the object
being raised or lowered must experience. At the earth's surface on
the equator, an object at the bottom of the elevator has an
orbital velocity of about 1038 mph (3693mi * 2pi / 24hrs). But by
the time this object has been raised to geosynchronous orbit
directly above that point on the equator, it's orbital velocity must
have been increased to about 6859 mph (26200mi * 2pi /24hrs).
Something has to impart the needed "sideways" acceleration to
achieve a delta-V of about 5821mph. Otherwise, the elevator cable
or shaft will bow backward (Westward) as the payload climbs the
cable, and bow forward as it climbs back down to earth.
It may be that the bowing just happens, but isn't big enough to
matter. Of course that would depend on the size of the payload
going up or down the cable, and possibly on the speed of ascent or
descent. But I just wondered if anyone can point me to a source
where this problem has really been addressed. I assume this
problem isn't a fatal flaw in the concept, but I would like to see
where someone has run the numbers to prove that.
Arthur, are you out there?
It won't work. The minimum energy curve from surface to
geosynchronous orbit is not a straight line. The added tensile
stress and length dooms a construct that cannot be built because
of its tensile stress and length. It must be constructed of
dielectrics or the Earth's billowing magnetosphere will roman
candle it by induction. If it is non-conductive, what powers the
gondola up and down? A funicular is asinine - the weight. The
stretch can only propagate at the speed of sound. 24,000 miles
is hours of delay. Cable inertia alone is damning.
NASA, "we will launch the Space Scuttle 5000 times to build the
Beanstalk."
Right. Uncle Al bets 2 and out.
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf
This is one area where I agree with Al.
He can't see how stupid a BH is, but a
Space Elevator is even stupider, and
somehow he senses that.
Idiot. I don't care if you agree with me or take time out to
wash your socks. The first is of no value whatsover; the second
won't obtain.
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf
.
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| User: "MorituriMax" |
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| Title: Re: Are there any Space Elevator experts here? |
27 Jul 2004 11:30:49 PM |
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Uncle Al wrote:
It won't work. The minimum energy curve from surface to
geosynchronous orbit is not a straight line. The added tensile
stress and length dooms a construct that cannot be built because
of its tensile stress and length. It must be constructed of
dielectrics or the Earth's billowing magnetosphere will roman
candle it by induction. If it is non-conductive, what powers the
gondola up and down? A funicular is asinine - the weight. The
stretch can only propagate at the speed of sound. 24,000 miles
is hours of delay. Cable inertia alone is damning.
Plus according to that loon elsewhere, you'd have hurricane force winds in it if
it was hollow.. snicker.
.
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