--- In spacesettlers@egroups.com, Ian Woollard
>
> Coil guns can do about 2.5 km/s which is enough for the
> moon (or punching though armour plate), but I think it runs
> out of 'steam' after that. The inductance of the coils gets
> to be a huge problem.

Actually, I've heard pessimists proclaim that coil guns can't even
get up to 1 km/s, which would mean that they couldn't even be used as
a lunar launcher. But as I remarked in "Making Dreams from
Moondust", I'm not sure a direct comparison can be drawn between the
kind of coil gun that the DoD funded, and the kind of mass driver
O'Neill was experimenting with. I know I did get a reply from Dr.
Les Snively, who worked with O'Neill on Mass Driver 3. He said that
the coil rise time the critics were pointing to as an insuperable
problem was an implicit part of their models.

I still consider it within the realm of possibility that those who
built that coilgun for the military simply erred in some fundamental
way, and that the mass driver may still work as anticipated.

And as you say later, the erosure problem rail guns have may be a
show stopper there.

Regards,
Mike Combs

The inductance will limit the acceleration not the velocity. The DOD
were building high acceleration devices (>100 g). I had did the
calculations about a decade ago, and came up with a safe acceleration
to escape velocity of about 70 m/s^2. I'll try to dig up my old notes
and transcribe it for everyone and you can try to find problems with
the physics.

Bill

--- In spacesettlers@egroups.com, "Mike Combs" wrote:
> --- In spacesettlers@egroups.com, Ian Woollard
> wrote:
> >
> > Coil guns can do about 2.5 km/s which is enough for the
> > moon (or punching though armour plate), but I think it runs
> > out of 'steam' after that. The inductance of the coils gets
> > to be a huge problem.
>
> Actually, I've heard pessimists proclaim that coil guns can't even
> get up to 1 km/s, which would mean that they couldn't even be used
as

Mike,

A magnetically suspended payload propelled via a rail using a linear motor has to work if the rail is of sufficient length and if the payload is not too heavy for the linear motor. I predict that this will be the primary mode of launching from the moon.

Cheers,

Tom
From: Mike Combs
To: spacesettlers@egroups.com
Sent: Wednesday, December 27, 2000 1:38 PM
Subject: [spacesettlers] Coil guns vs. mass drivers

--- In spacesettlers@egroups.com, Ian Woollard
wrote:
>
> Coil guns can do about 2.5 km/s which is enough for the
> moon (or punching though armour plate), but I think it runs
> out of 'steam' after that. The inductance of the coils gets
> to be a huge problem.

Actually, I've heard pessimists proclaim that coil guns can't even
get up to 1 km/s, which would mean that they couldn't even be used as
a lunar launcher. But as I remarked in "Making Dreams from
Moondust", I'm not sure a direct comparison can be drawn between the
kind of coil gun that the DoD funded, and the kind of mass driver
O'Neill was experimenting with. I know I did get a reply from Dr.
Les Snively, who worked with O'Neill on Mass Driver 3. He said that
the coil rise time the critics were pointing to as an insuperable
problem was an implicit part of their models.

I still consider it within the realm of possibility that those who
built that coilgun for the military simply erred in some fundamental
way, and that the mass driver may still work as anticipated.

And as you say later, the erosure problem rail guns have may be a
show stopper there.

Regards,
Mike Combs

A magnetically suspended payload propelled via a rail using a linear motor has to work if the rail is of sufficient length and if the payload is not too heavy for the linear motor. I predict that this will be the primary mode of launching from the moon.

Cheers,

Tom
From:
Mike Combs
To:
spacesettlers@egroups.com
Sent:
Wednesday, December 27, 2000 1:38 PM
Subject:
[spacesettlers] Coil guns vs. mass drivers
--- In
spacesettlers@egroups.com
, Ian Woollard <
ian.woollard@t
...>
>
> Coil guns can do about 2.5 km/s which is enough for the
> moon (or punching though armour plate), but I think it runs
> out of 'steam' after that. The inductance of the coils gets
> to be a huge problem.
Actually, I've heard pessimists proclaim that coil guns can't even
get up to 1 km/s, which would mean that they couldn't even be used as
a lunar launcher. But as I remarked in "Making Dreams from
Moondust", I'm not sure a direct comparison can be drawn between the
kind of coil gun that the DoD funded, and the kind of mass driver
O'Neill was experimenting with. I know I did get a reply from Dr.
Les Snively, who worked with O'Neill on Mass Driver 3. He said that
the coil rise time the critics were pointing to as an insuperable
problem was an implicit part of their models.
I still consider it within the realm of possibility that those who
built that coilgun for the military simply erred in some fundamental
way, and that the mass driver may still work as anticipated.
And as you say later, the erosure problem rail guns have may be a
show stopper there.
Regards,
Mike Combs

Bill,

It would be helpful to see a sketch of the design being considered. If the acceleration is similar to the linear motor concept being used for maglev trains, then I don't understand the design limitation. At the higher velocity sections, the propulsion magnets could be spaced further apart if timing becomes an issue. In a vacuum, the only constraint I am aware of is the ability to construct the magnetic support rails exceedingly straight. The structure might be blown around by the solar wind :-)

Tom
From: bill t
To: spacesettlers@egroups.com
Sent: Wednesday, December 27, 2000 7:36 PM
Subject: [spacesettlers] Re: Coil guns vs. mass drivers

The inductance will limit the acceleration not the velocity. The DOD
were building high acceleration devices (>100 g). I had did the
calculations about a decade ago, and came up with a safe acceleration
to escape velocity of about 70 m/s^2. I'll try to dig up my old notes
and transcribe it for everyone and you can try to find problems with
the physics.

Bill

--- In spacesettlers@egroups.com, "Mike Combs" wrote:
> --- In spacesettlers@egroups.com, Ian Woollard
> wrote:
> >
> > Coil guns can do about 2.5 km/s which is enough for the
> > moon (or punching though armour plate), but I think it runs
> > out of 'steam' after that. The inductance of the coils gets
> > to be a huge problem.
>
> Actually, I've heard pessimists proclaim that coil guns can't even
> get up to 1 km/s, which would mean that they couldn't even be used
as
> a lunar launcher. But as I remarked in "Making Dreams from
> Moondust", I'm not sure a direct comparison can be drawn between the
> kind of coil gun that the DoD funded, and the kind of mass driver
> O'Neill was experimenting with. I know I did get a reply from Dr.
> Les Snively, who worked with O'Neill on Mass Driver 3. He said that
> the coil rise time the critics were pointing to as an insuperable
> problem was an implicit part of their models.
>
> I still consider it within the realm of possibility that those who
> built that coilgun for the military simply erred in some fundamental
> way, and that the mass driver may still work as anticipated.
>
> And as you say later, the erosure problem rail guns have may be a
> show stopper there.
>
> Regards,
> Mike Combs

It would be helpful to see a sketch of the design being considered. If the acceleration is similar to the linear motor concept being used for maglev trains, then I don't understand the design limitation. At the higher velocity sections, the propulsion magnets could be spaced further apart if timing becomes an issue. In a vacuum, the only constraint I am aware of is the ability to construct the magnetic support rails exceedingly straight. The structure might be blown around by the solar wind :-)

Tom
From:
bill t
To:
spacesettlers@egroups.com
Sent:
Wednesday, December 27, 2000 7:36 PM
Subject:
[spacesettlers] Re: Coil guns vs. mass drivers
The inductance will limit the acceleration not the velocity. The DOD
were building high acceleration devices (>100 g). I had did the
calculations about a decade ago, and came up with a safe acceleration
to escape velocity of about 70 m/s^2. I'll try to dig up my old notes
and transcribe it for everyone and you can try to find problems with
the physics.
Bill
--- In spacesettlers@egroups.com, "Mike Combs"
> --- In spacesettlers@egroups.com, Ian Woollard
> wrote:
> >
> > Coil guns can do about 2.5 km/s which is enough for the
> > moon (or punching though armour plate), but I think it runs
> > out of 'steam' after that. The inductance of the coils gets
> > to be a huge problem.
>
> Actually, I've heard pessimists proclaim that coil guns can't even
> get up to 1 km/s, which would mean that they couldn't even be used
as

A diagram would be great if had a scanner to scan it in.

I think you are looking at it from the wrong point of view. The moving
magnetic field will cause induction in the stationary coils. This
induction will cause a decrese in current flow. The capsule acts like
a linear generator. It is acedemic though. For long induction motors
(which is what this is) this doesn't become a problem.

Being straight is not a real prblem. In fact the structure will be
curved since it is on a planet.

This post was to answer that the maximum speed was limited to about 2
km/s. This is true only for short high acceleration coil guns. For
longer guns the induction problem is still there but the maximum
velocity is much higher for longer (1000 km length) designs.

Bill

--- In spacesettlers@egroups.com, "Tom Tucker (Olympia)"
wrote:
> Bill,
>
> It would be helpful to see a sketch of the design being considered.
If the acceleration is similar to the linear motor concept being used
for maglev trains, then I don't understand the design limitation. At
the higher velocity sections, the propulsion magnets could be spaced
further apart if timing becomes an issue. In a vacuum, the only
constraint I am aware of is the ability to construct the magnetic
support rails exceedingly straight. The structure might be blown
around by the solar wind :-)
>
> Tom
> From: bill t
> To: spacesettlers@egroups.com
> Sent: Wednesday, December 27, 2000 7:36 PM
> Subject: [spacesettlers] Re: Coil guns vs. mass drivers
>
> The inductance will limit the acceleration not the velocity. The
DOD
> were building high acceleration devices (>100 g). I had did the
> calculations about a decade ago, and came up with a safe
acceleration
> to escape velocity of about 70 m/s^2. I'll try to dig up my old
notes
> and transcribe it for everyone and you can try to find problems
with
> the physics.
>
> Bill
>
> --- In spacesettlers@egroups.com, "Mike Combs"
> > --- In spacesettlers@egroups.com, Ian Woollard

> > wrote:
> > >
> > > Coil guns can do about 2.5 km/s which is enough for the
> > > moon (or punching though armour plate), but I think it runs
> > > out of 'steam' after that. The inductance of the coils gets
> > > to be a huge problem.
> >
> > Actually, I've heard pessimists proclaim that coil guns can't
even
> > get up to 1 km/s, which would mean that they couldn't even be
used
> as
> > a lunar launcher. But as I remarked in "Making Dreams from
> > Moondust", I'm not sure a direct comparison can be drawn between
the
> > kind of coil gun that the DoD funded, and the kind of mass
driver
> > O'Neill was experimenting with. I know I did get a reply from
Dr.
> > Les Snively, who worked with O'Neill on Mass Driver 3. He said
that
> > the coil rise time the critics were pointing to as an
insuperable
> > problem was an implicit part of their models.
> >
> > I still consider it within the realm of possibility that those
who
> > built that coilgun for the military simply erred in some
fundamental
> > way, and that the mass driver may still work as anticipated.
> >
> > And as you say later, the erosure problem rail guns have may be
a

--- In spacesettlers@egroups.com, "bill t" wrote:
>
> The inductance will limit the acceleration not the velocity. The DOD
> were building high acceleration devices (>100 g). I had did the
> calculations about a decade ago, and came up with a safe
acceleration
> to escape velocity of about 70 m/s^2. I'll try to dig up my old
notes
> and transcribe it for everyone and you can try to find problems with
> the physics.
show stopper there.

The actual argument made was that the rise/fall time of each coil
limited the maximum velocity to below the km/sec range. Like I said,
whether this was right or wrong, I'm unsure.

Dr. Snively said that one thing O'Neill's mass driver did to solve
the coil rise/fall time problem was that at the high speed end of the
mass driver, you went from fewer coils with multiple turns to greater
numbers of single-turn coils. I've never heard anyone say whether or
not the DoD funded coil gun team ever tried this approach.

O'Neill assumed (and achieved with models) an acceleration of 1,800
G's.

Regards,
Mike Combs

Bill,

The timing circuit must apply a magnetic field to "pull" the payload until it is centered with the magnetic coil at which time the power is dropped. It is after this point that the passing magnetic will induce their voltage. Hence, if there is a way to transfer the magnetic field/current to the next magnetic coil and to open the circuit up so that it does not conduct electricity, then there will be no induced current to impede the payload.

Tom
From: bill t
To: spacesettlers@egroups.com
Sent: Sunday, December 31, 2000 9:03 AM
Subject: [spacesettlers] Re: Coil guns vs. mass drivers

A diagram would be great if had a scanner to scan it in.

I think you are looking at it from the wrong point of view. The moving
magnetic field will cause induction in the stationary coils. This
induction will cause a decrese in current flow. The capsule acts like
a linear generator. It is acedemic though. For long induction motors
(which is what this is) this doesn't become a problem.

Being straight is not a real prblem. In fact the structure will be
curved since it is on a planet.

This post was to answer that the maximum speed was limited to about 2
km/s. This is true only for short high acceleration coil guns. For
longer guns the induction problem is still there but the maximum
velocity is much higher for longer (1000 km length) designs.

Bill

--- In spacesettlers@egroups.com, "Tom Tucker (Olympia)"
wrote:
> Bill,
>
> It would be helpful to see a sketch of the design being considered.
If the acceleration is similar to the linear motor concept being used
for maglev trains, then I don't understand the design limitation. At
the higher velocity sections, the propulsion magnets could be spaced
further apart if timing becomes an issue. In a vacuum, the only
constraint I am aware of is the ability to construct the magnetic
support rails exceedingly straight. The structure might be blown
around by the solar wind :-)
>
> Tom
> From: bill t
> To: spacesettlers@egroups.com
> Sent: Wednesday, December 27, 2000 7:36 PM
> Subject: [spacesettlers] Re: Coil guns vs. mass drivers
>
> The inductance will limit the acceleration not the velocity. The
DOD
> were building high acceleration devices (>100 g). I had did the
> calculations about a decade ago, and came up with a safe
acceleration
> to escape velocity of about 70 m/s^2. I'll try to dig up my old
notes
> and transcribe it for everyone and you can try to find problems
with
> the physics.
>
> Bill
>
> --- In spacesettlers@egroups.com, "Mike Combs"
wrote:
> > --- In spacesettlers@egroups.com, Ian Woollard

> > wrote:
> > >
> > > Coil guns can do about 2.5 km/s which is enough for the
> > > moon (or punching though armour plate), but I think it runs
> > > out of 'steam' after that. The inductance of the coils gets
> > > to be a huge problem.
> >
> > Actually, I've heard pessimists proclaim that coil guns can't
even
> > get up to 1 km/s, which would mean that they couldn't even be
used
> as
> > a lunar launcher. But as I remarked in "Making Dreams from
> > Moondust", I'm not sure a direct comparison can be drawn between
the
> > kind of coil gun that the DoD funded, and the kind of mass
driver
> > O'Neill was experimenting with. I know I did get a reply from
Dr.
> > Les Snively, who worked with O'Neill on Mass Driver 3. He said
that
> > the coil rise time the critics were pointing to as an
insuperable
> > problem was an implicit part of their models.
> >
> > I still consider it within the realm of possibility that those
who
> > built that coilgun for the military simply erred in some
fundamental
> > way, and that the mass driver may still work as anticipated.
> >
> > And as you say later, the erosure problem rail guns have may be
a
> > show stopper there.
> >
> > Regards,
> > Mike Combs
>

The timing circuit must apply a magnetic field to "pull" the payload until it is centered with the magnetic coil at which time the power is dropped. It is after this point that the passing magnetic will induce their voltage. Hence, if there is a way to transfer the magnetic field/current to the next magnetic coil and to open the circuit up so that it does not conduct electricity, then there will be no induced current to impede the payload.

Tom
From:
bill t
To:
spacesettlers@...m
Sent:
Sunday, December 31, 2000 9:03 AM
Subject:
[spacesettlers] Re: Coil guns vs. mass drivers
A diagram would be great if had a scanner to scan it in.
I think you are looking at it from the wrong point of view. The moving
magnetic field will cause induction in the stationary coils. This
induction will cause a decrese in current flow. The capsule acts like
a linear generator. It is acedemic though. For long induction motors
(which is what this is) this doesn't become a problem.
Being straight is not a real prblem. In fact the structure will be
curved since it is on a planet.
This post was to answer that the maximum speed was limited to about 2
km/s. This is true only for short high acceleration coil guns. For
longer guns the induction problem is still there but the maximum
velocity is much higher for longer (1000 km length) designs.
Bill
--- In spacesettlers@egroups.com, "Tom Tucker (Olympia)"
> Bill,
>
It would be helpful to see a sketch of the design being considered.
If the acceleration is similar to the linear motor concept being used
for maglev trains, then I don't understand the design limitation. At
the higher velocity sections, the propulsion magnets could be spaced
further apart if timing becomes an issue. In a vacuum, the only
constraint I am aware of is the ability to construct the magnetic
support rails exceedingly straight. The structure might be blown
around by the solar wind :-)
>
> Tom
> From: bill t
To: spacesettlers@egroups.com
> Sent: Wednesday, December 27, 2000 7:36 PM
> Subject: [spacesettlers] Re: Coil guns vs. mass drivers
>
The inductance will limit the acceleration not the velocity. The
DOD
> were building high acceleration devices (>100 g). I had did the
> calculations about a decade ago, and came up with a safe
acceleration
> to escape velocity of about 70 m/s^2. I'll try to dig up my old
notes
> and transcribe it for everyone and you can try to find problems
with
> the physics.
>
> Bill
>
> --- In spacesettlers@egroups.com, "Mike Combs"
> > --- In spacesettlers@egroups.com, Ian Woollard
> > wrote:
> > >
> > > Coil guns can do about 2.5 km/s which is enough for the
> > > moon (or punching though armour plate), but I think it runs
> > > out of 'steam' after that. The inductance of the coils gets
> > > to be a huge problem.
>
> > Actually, I've heard pessimists proclaim that coil guns can't
even
> > get up to 1 km/s, which would mean that they couldn't even be
used
> as
> > a lunar launcher. But as I remarked in "Making Dreams from
> > Moondust", I'm not sure a direct comparison can be drawn between
the
> > kind of coil gun that the DoD funded, and the kind of mass
driver
> > O'Neill was experimenting with. I know I did get a reply from
Dr.
> > Les Snively, who worked with O'Neill on Mass Driver 3. He said
that
> > the coil rise time the critics were pointing to as an
insuperable
> > problem was an implicit part of their models.
> >
> > I still consider it within the realm of possibility that those
who
> built that coilgun for the military simply erred in some
fundamental
> > way, and that the mass driver may still work as anticipated.
> >
> > And as you say later, the erosure problem rail guns have may be
a

--- In spacesettlers@egroups.com, "Tom Tucker (Olympia)"
wrote:
> Mike,
>
> A magnetically suspended payload propelled via a rail using a
> linear motor has to work if the rail is of sufficient length and if
> the payload is not too heavy for the linear motor. I predict that
> this will be the primary mode of launching from the moon.

The argument that the pessimists were making to me was that above a
certain speed, an accelerating coil would not be able to switch on
and off fast enough to contribute any further acceleration. That no
matter to what extent you extended the length of the accelerator, you
wouldn't get any further acceleration regardless.

But like I said in my article, I'm skeptical, if for no other reason
than the implication that Prof. Gerard O'Neill, who was with
Princeton's Institute of Advanced Study, absent-mindedly neglected a
principle of electricity which I learned in my first or second year
of college.

Regards,
Mike Combs

--- In spacesettlers@egroups.com, "bill t" wrote:
>
> A diagram would be great if had a scanner to scan it in.
>
> I think you are looking at it from the wrong point of view. The
moving
> magnetic field will cause induction in the stationary coils. This
> induction will cause a decrese in current flow. The capsule acts
like
> a linear generator. It is acedemic though. For long induction motors
> (which is what this is) this doesn't become a problem.
>
> Being straight is not a real prblem. In fact the structure will be
> curved since it is on a planet.
>
> This post was to answer that the maximum speed was limited to about
2
> km/s. This is true only for short high acceleration coil guns. For
> longer guns the induction problem is still there but the maximum
> velocity is much higher for longer (1000 km length) designs.
>
> Bill
>

Bill,

I've just cleaned my glasses but the numbers didn't change so I
have to assume that something else is wrong. Tell me are you really
suggesting a magnetic launch system with a coil or sections 1000,
that's one thousand kilometres long (1500 in an earlier post), that
is 620+ miles or did you miss a decimal place? Now I could sit down
with paper and pencil to work out what the exit velocity of a trip of
1000 Km at 5G works out to but it seems a little, .... overdone. On
the other hand putting aside how fast you are going, where on Earth
would you put it, pardon the pun. I'm an admitted space nut but even
I wouldn't want to live anywhere near to it and I can just imagine
what Ned Ludds green commandos would think about it. Is this a case
of sitting back and seeing how crazy you can get or are you serious?

Darren

Instead of pulling, you can "push". The capsule would 'surf' on an
accelerating electromagnetic wave.

Most coilguns try to use both the push and pull. Pull until the
capsule is centered, then push. This scenerio is limited by the coil
induction, and the permability of the wire.

Even if there is some fundemental limit on coil guns they still would
be advantageous. It would allow to get the first 2-3 km/s at the
lowest possible cost where it is most expensive to use a chemical
rocket. Then use a second stage chemical rocket to LEO. At LEO you
tranfer to a big, low acceleration ship that is in a long ellipitcal
orbit to begin with.

Bill

--- In spacesettlers@egroups.com, "Tom Tucker (Olympia)"
wrote:
> Bill,
>
> The timing circuit must apply a magnetic field to "pull" the payload
until it is centered with the magnetic coil at which time the power is
dropped. It is after this point that the passing magnetic will induce
their voltage. Hence, if there is a way to transfer the magnetic
field/current to the next magnetic coil and to open the circuit up so
that it does not conduct electricity, then there will be no induced
current to impede the payload.
>
> Tom
> From: bill t
> To: spacesettlers@egroups.com
> Sent: Sunday, December 31, 2000 9:03 AM
> Subject: [spacesettlers] Re: Coil guns vs. mass drivers
>
> A diagram would be great if had a scanner to scan it in.
>
> I think you are looking at it from the wrong point of view. The
moving
> magnetic field will cause induction in the stationary coils. This
> induction will cause a decrese in current flow. The capsule acts
like
> a linear generator. It is acedemic though. For long induction
motors
> (which is what this is) this doesn't become a problem.
>
> Being straight is not a real prblem. In fact the structure will be
> curved since it is on a planet.
>
> This post was to answer that the maximum speed was limited to
about 2
> km/s. This is true only for short high acceleration coil guns. For
> longer guns the induction problem is still there but the maximum
> velocity is much higher for longer (1000 km length) designs.
>
> Bill
>
> --- In spacesettlers@egroups.com, "Tom Tucker (Olympia)"
> wrote:
> > Bill,
> >
> > It would be helpful to see a sketch of the design being
considered.
> If the acceleration is similar to the linear motor concept being
used
> for maglev trains, then I don't understand the design limitation.
At
> the higher velocity sections, the propulsion magnets could be
spaced
> further apart if timing becomes an issue. In a vacuum, the only
> constraint I am aware of is the ability to construct the magnetic
> support rails exceedingly straight. The structure might be blown
> around by the solar wind :-)
> >
> > Tom
> > From: bill t
> > To: spacesettlers@egroups.com
> > Sent: Wednesday, December 27, 2000 7:36 PM
> > Subject: [spacesettlers] Re: Coil guns vs. mass drivers
> >
> >
> >
> > The inductance will limit the acceleration not the velocity.
The
> DOD
> > were building high acceleration devices (>100 g). I had did
the
> > calculations about a decade ago, and came up with a safe
> acceleration
> > to escape velocity of about 70 m/s^2. I'll try to dig up my
old
> notes
> > and transcribe it for everyone and you can try to find
problems
> with
> > the physics.
> >
> > Bill
> >
> >
> >
> > --- In spacesettlers@egroups.com, "Mike Combs"

> wrote:
> > > --- In spacesettlers@egroups.com, Ian Woollard
>
> > > wrote:
> > > >
> > > > Coil guns can do about 2.5 km/s which is enough for the
> > > > moon (or punching though armour plate), but I think it
runs
> > > > out of 'steam' after that. The inductance of the coils
gets
> > > > to be a huge problem.
> > >
> > > Actually, I've heard pessimists proclaim that coil guns
can't
> even
> > > get up to 1 km/s, which would mean that they couldn't even
be
> used
> > as
> > > a lunar launcher. But as I remarked in "Making Dreams from
> > > Moondust", I'm not sure a direct comparison can be drawn
between
> the
> > > kind of coil gun that the DoD funded, and the kind of mass
> driver
> > > O'Neill was experimenting with. I know I did get a reply
from
> Dr.
> > > Les Snively, who worked with O'Neill on Mass Driver 3. He
said
> that
> > > the coil rise time the critics were pointing to as an
> insuperable
> > > problem was an implicit part of their models.
> > >
> > > I still consider it within the realm of possibility that
those
> who
> > > built that coilgun for the military simply erred in some
> fundamental
> > > way, and that the mass driver may still work as anticipated.
> > >
> > > And as you say later, the erosure problem rail guns have may
be

From: bill t [mailto:qwerty172@...]

Instead of pulling, you can "push". The capsule would 'surf' on an
accelerating electromagnetic wave.

Most coilguns try to use both the push and pull. Pull until the
capsule is centered, then push. This scenerio is limited by the coil
induction, and the permability of the wire.

I happen to know that O'Neill's mass driver 3 model used pull-only. They
had decided that the strong centering forces of the pull-only strategy
eliminated the need for guidance strips in the high-acceleration portion of
the driver, which improved coupling and hence efficiency.

If Bill Kowan's gun was pull/push, then that's yet one more reason to
consider it a different animal from O'Neill's mass driver.

Regards,

Mike Combs

From:
bill t [mailto:qwerty172@...]
Instead of pulling, you can "push". The capsule would 'surf' on an
accelerating electromagnetic wave.
Most coilguns try to use both the push and pull. Pull until the
capsule is centered, then push. This scenerio is limited by the coil
induction, and the permability of the wire.

I happen to know that O'Neill's mass driver 3 model used pull-only. They had decided that the strong centering forces of the pull-only strategy eliminated the need for guidance strips in the high-acceleration portion of the driver, which improved coupling and hence efficiency.

If Bill Kowan's gun was pull/push, then that's yet one more reason to consider it a different animal from O'Neill's mass driver.

Regards,
Mike Combs

escape velocity = 11.2 km/s

ad = 1/2 (v0^2 - v1^2 ) v1=0 (stationary)

a= 5m/s^2
5d=1/2(11 200^2)
d= 1.254x10^7 m ~ 1250 km

Where to put it? Australian desert, Sahara desert, Canadian praries.
Siberia? I personally like floating on kilometer wide balloons.

Why would you care if you live beside it? Realistially most of it
would probably be buried anyway. If it to be built, what I imagine is
a strip of land 1 km long by 1500 km wide restricted area, possibly
with overpasses for highways. People live beside railway tracks.

Its a hard sell for the US because there is little uninhabited areas.

You can literally drive a 1000 km along the Canadian praries between
winnipeg and regina without ever seeing signs of life. It is one big
wheat field. Becoming the space hub of the planet would be a fairly
easy sell to Sasketchwan.

Bill

--- In spacesettlers@egroups.com, "Darren Brown" wrote:
> --- In spacesettlers@egroups.com, "bill t" wrote:
> >
> > A diagram would be great if had a scanner to scan it in.
> >
> > I think you are looking at it from the wrong point of view. The
> moving
> > magnetic field will cause induction in the stationary coils. This
> > induction will cause a decrese in current flow. The capsule acts
> like
> > a linear generator. It is acedemic though. For long induction
motors
> > (which is what this is) this doesn't become a problem.
> >
> > Being straight is not a real prblem. In fact the structure will be
> > curved since it is on a planet.
> >
> > This post was to answer that the maximum speed was limited to
about
> 2
> > km/s. This is true only for short high acceleration coil guns. For
> > longer guns the induction problem is still there but the maximum
> > velocity is much higher for longer (1000 km length) designs.
> >
> > Bill
> >
> Bill,
>
> I've just cleaned my glasses but the numbers didn't change so I
> have to assume that something else is wrong. Tell me are you really
> suggesting a magnetic launch system with a coil or sections 1000,
> that's one thousand kilometres long (1500 in an earlier post), that
> is 620+ miles or did you miss a decimal place? Now I could sit down
> with paper and pencil to work out what the exit velocity of a trip
of
> 1000 Km at 5G works out to but it seems a little, .... overdone. On
> the other hand putting aside how fast you are going, where on Earth
> would you put it, pardon the pun. I'm an admitted space nut but
even

--- In spacesettlers@egroups.com, "bill t" wrote:
>
> escape velocity = 11.2 km/s
>
> ad = 1/2 (v0^2 - v1^2 ) v1=0 (stationary)
>
> a= 5m/s^2
> 5d=1/2(11 200^2)
> d= 1.254x10^7 m ~ 1250 km
>
> Where to put it? Australian desert, Sahara desert, Canadian praries.
> Siberia? I personally like floating on kilometer wide balloons.
>
> Why would you care if you live beside it? Realistially most of it
> would probably be buried anyway. If it to be built, what I imagine
is
> a strip of land 1 km long by 1500 km wide restricted area, possibly
> with overpasses for highways. People live beside railway tracks.
>
> Its a hard sell for the US because there is little uninhabited
areas.
>
> You can literally drive a 1000 km along the Canadian praries between
> winnipeg and regina without ever seeing signs of life. It is one big
> wheat field. Becoming the space hub of the planet would be a fairly
> easy sell to Sasketchwan.
>
> Bill
>

Bill,

Right now I'm really pressed for time but something still seems out
of wack to me, so when I get a few seconds, I'll drag out my
reference book from under the house, blow off the decades of dust and
see if the misty dim equation I'm remembering is even near right.
But a few points first, I now see that this is in reference to the
file you uploaded and I've only just opened, so I'll read the rest of
that before getting back to you. Next, let me tell you, the local
concerned citizens groups would set up a gibbet in the town square
with a noose just your size if you mentioned building something like
that, even out where the only one to notice are frill necked lizards
and goannas. The Federal government is trying to build a new airport
for Sydney and are finding the political price way too high, plus
changes to the laws here a while back means that you would need to
get the governments, federal/state/local on side as well as any
aboriginal land councils + groups with an histroical connection to
the area and any property owners on side and anybody with mineral
rights (not always the property owner), a big ask, very big, also you
couldn't put any part near the old testing grounds or rocket ranges
or the joint defence stations or anything underground near the
artesian basin , that cut out a big area, in fact I'm not sure you
could get 1500 km in a line without running foul of one of the above
but I could be wrong. Then you would need to overcome a major
problem that has always plagued us in Australia, take a look at a
good map and see how many roads there are near the centre and then
look how far it is from us to anywhere else in the world,
infrastructure and distance are killers. And just before I go a
quick calculation gives me a speed about 6 time more that you need to
get to LEO from your 1500 Km long coil gun, ~11 Km/sec for escape ~5-
7 for orbit your coil comes around 38.3 Km/sec. I'll check that but
maybe somebody else out there might take a look because I admit I
will need to look in the reference books to see if what I have in
front of me is right. Anybody else got an exit speed for 15 million
metres at 49 metres per second squared?

Darren

I would love to see the length being wrong.

The problems you mentioned for Australia are also true for Canada.
Transportation in Canadian Praries might be slightly better, but its
not the interstate system the U.S has.

It may not be as big a political nightmare here, because the area is
mostly private property, but is very sparsely populated.

In reality it becomes a question of how much is space based technology
worth to the planet?

Bill

--- In spacesettlers@egroups.com, "Darren Brown" wrote:
> --- In spacesettlers@egroups.com, "bill t" wrote:
> >
> > escape velocity = 11.2 km/s
> >
> > ad = 1/2 (v0^2 - v1^2 ) v1=0 (stationary)
> >
> > a= 5m/s^2
> > 5d=1/2(11 200^2)
> > d= 1.254x10^7 m ~ 1250 km
> >
> > Where to put it? Australian desert, Sahara desert, Canadian
praries.
> > Siberia? I personally like floating on kilometer wide balloons.
> >
> > Why would you care if you live beside it? Realistially most of it
> > would probably be buried anyway. If it to be built, what I imagine
> is
> > a strip of land 1 km long by 1500 km wide restricted area,
possibly
> > with overpasses for highways. People live beside railway tracks.
> >
> > Its a hard sell for the US because there is little uninhabited
> areas.
> >
> > You can literally drive a 1000 km along the Canadian praries
between
> > winnipeg and regina without ever seeing signs of life. It is one
big
> > wheat field. Becoming the space hub of the planet would be a
fairly
> > easy sell to Sasketchwan.
> >
> > Bill
> >
> Bill,
>
> Right now I'm really pressed for time but something still seems out
> of wack to me, so when I get a few seconds, I'll drag out my
> reference book from under the house, blow off the decades of dust
and
> see if the misty dim equation I'm remembering is even near right.
> But a few points first, I now see that this is in reference to the
> file you uploaded and I've only just opened, so I'll read the rest
of
> that before getting back to you. Next, let me tell you, the local
> concerned citizens groups would set up a gibbet in the town square
> with a noose just your size if you mentioned building something like
> that, even out where the only one to notice are frill necked lizards
> and goannas. The Federal government is trying to build a new
airport
> for Sydney and are finding the political price way too high, plus
> changes to the laws here a while back means that you would need to
> get the governments, federal/state/local on side as well as any
> aboriginal land councils + groups with an histroical connection to
> the area and any property owners on side and anybody with mineral
> rights (not always the property owner), a big ask, very big, also
you
> couldn't put any part near the old testing grounds or rocket ranges
> or the joint defence stations or anything underground near the
> artesian basin , that cut out a big area, in fact I'm not sure you
> could get 1500 km in a line without running foul of one of the above
> but I could be wrong. Then you would need to overcome a major
> problem that has always plagued us in Australia, take a look at a
> good map and see how many roads there are near the centre and then
> look how far it is from us to anywhere else in the world,
> infrastructure and distance are killers. And just before I go a
> quick calculation gives me a speed about 6 time more that you need
to
> get to LEO from your 1500 Km long coil gun, ~11 Km/sec for escape
~5-

--- In spacesettlers@egroups.com, "bill t" wrote:
>
> I would love to see the length being wrong.
>
> The problems you mentioned for Australia are also true for Canada.
> Transportation in Canadian Praries might be slightly better, but its
> not the interstate system the U.S has.
>
> It may not be as big a political nightmare here, because the area is
> mostly private property, but is very sparsely populated.
>
> In reality it becomes a question of how much is space based
technology
> worth to the planet?
>
> Bill
>

Bill,

A very unexpected change to my timetable, completely ruining
everything I've set-up for the next week, not that they care, has
given me the chance to look at my books and numbers and I've got good
news and bad news.

First the bad news, due to declining mental faculties, failing
eyesight, overwork and general stress, environmental factors and
other external events beyond my control, as well as a decimal point
that jumped into the wrong place, all by itself (well that's my story
and I'm sticking to it). I'm forced to admit that 1500 Kms is only
1.5 million metres not 15 million (sound of a person muttering under
his breath, while looking at the ground and shifting his feet in an
embarrassed manner) but the rest of the calculations were right or so
my text books tell me. Now the good news, your length is still not
quite right, in a way. I'm uploading an Excel spreadsheet to give
you the basic numbers (a very quick and dirty sheet so don't expect
bells and whistles). If you are going to get a load up to escape
velocity, ~11 Kms/sec then you will need a launch system only 12,124
Kms long, not 1500, not much of a gain really. Better news is why
that fast? All you really need is to get to orbit and then you can
use low thrust/ high impulse engines to get you higher or even
tethers or some other way, in that case you only need a launch unit,
say 350 Kms long. Still big but much better than 1500 Kms. Which
brings up a point, why use it at all? I read the rest of your upload
and it changes a few things. These are in no particular order;

Given that you are really looking at an end of the world situation
then any objections about environmental damage are nonsense. That
being the case you are thinking much too small and at the same time
too big. Why take so many people? Certainly you don't want to leave
anybody behind but given the time line you are looking at most of the
population today will be dead before anything happen so if you had
good population control you would only have to move a fraction of the
people you first had. This is also a problem for you as a lot of
people will not want to work to solve a problem that isn't going to
happen until after they and their children are gone, they will try to
put it off to later.

Next you will need a lot of infrastructure in space to do this and
fast, so I'd be going over and digging out the plans for Orion. The
Australian desert would be just about perfect for building and
launching something like old bang-bang and it would just about put a
fully built and working base into orbit. Fallout, I hear you say, so
what, soon it is going to a lot hotter than that.

Massive mining of the solar system will give you all the raw
materials you need so you shouldn't need to lift from deep gravity
wells. That just leaves people to get from Earth. I'd be using a
large Lightcraft and it's cousin that uses microwaves from orbit.
Also do you need to take the whole person or just the eggs and
sperm. Move as many people as you can and then germ plasm from as
many others as possible to give you the maximum genetic variation.

Bottom line, if you are evacuating then why bother to use a launch
system as clean as a coil gun, you're not coming back and what is
left is soon going to be toast, do whatever it takes.

Of course if you are not in that situation you might want to consider
looking at laser launch systems for people and maybe
magnet/chemical/plasma launch for cargo that isn't so fragile.

Darren

Actually, I came up with 1244 km, using 11.2km/s. The lowest I could
convince myself was 500km.

My scenerio moves less than 30% of the population, and it does assume
a rather stringent population control.

The putting it off for tommorrow was a basic assumption I said would
not happen.

The reason to move as many people off is more pyschological. If you
start picking and choosing, those that know they will be left behind
won't co-operate. Also I am trusting sheer numbers rather than the
technological fix.

Very few people know that 90% of all the colonists leaving England in
the 17Th century never made it to their destination.

The orions may be used to move a small initial population. But my
scenerio is to evacuate the planet. To do that you need 75 launchers
launching 1 capsule with 200 people in it every 20 minutes for 150
years straight. There s no rocket system in the world that can compete
with a launch system.

If we were looking at today. To justify the cost of building the
launcher you would need a project that needs to launch something daily
or hourly. Lowering the final velocity is probably acceptable, and
with your system we could get down to 350km. Depending on what you are
launching you could increase the acceleration by a factor of 10, so we
need 35km.

The actual launcher would be sections of tube, so I could see the
whole length being mass produced in a factory once the design is
established and transported to its final position and hooked up. Then
buried after the fact.

I can't even think of putting together a construction cost for a
minimal system, but launch costs as low as $10 a kg should be normal.

What's a Lightcraft?

Bill

--- In spacesettlers@egroups.com, "Darren Brown" wrote:
> --- In spacesettlers@egroups.com, "bill t" wrote:
> >
> > I would love to see the length being wrong.
> >
> > The problems you mentioned for Australia are also true for Canada.
> > Transportation in Canadian Praries might be slightly better, but
its
> > not the interstate system the U.S has.
> >
> > It may not be as big a political nightmare here, because the area
is
> > mostly private property, but is very sparsely populated.
> >
> > In reality it becomes a question of how much is space based
> technology
> > worth to the planet?
> >
> > Bill
> >
> Bill,
>
> A very unexpected change to my timetable, completely ruining
> everything I've set-up for the next week, not that they care, has
> given me the chance to look at my books and numbers and I've got
good
> news and bad news.
>
> First the bad news, due to declining mental faculties, failing
> eyesight, overwork and general stress, environmental factors and
> other external events beyond my control, as well as a decimal point
> that jumped into the wrong place, all by itself (well that's my
story
> and I'm sticking to it). I'm forced to admit that 1500 Kms is only
> 1.5 million metres not 15 million (sound of a person muttering under
> his breath, while looking at the ground and shifting his feet in an
> embarrassed manner) but the rest of the calculations were right or
so
> my text books tell me. Now the good news, your length is still not
> quite right, in a way. I'm uploading an Excel spreadsheet to give
> you the basic numbers (a very quick and dirty sheet so don't expect
> bells and whistles). If you are going to get a load up to escape
> velocity, ~11 Kms/sec then you will need a launch system only 12,124
> Kms long, not 1500, not much of a gain really. Better news is why
> that fast? All you really need is to get to orbit and then you can
> use low thrust/ high impulse engines to get you higher or even
> tethers or some other way, in that case you only need a launch unit,
> say 350 Kms long. Still big but much better than 1500 Kms. Which
> brings up a point, why use it at all? I read the rest of your
upload
> and it changes a few things. These are in no particular order;
>
> Given that you are really looking at an end of the world situation
> then any objections about environmental damage are nonsense. That
> being the case you are thinking much too small and at the same time
> too big. Why take so many people? Certainly you don't want to
leave
> anybody behind but given the time line you are looking at most of
the
> population today will be dead before anything happen so if you had
> good population control you would only have to move a fraction of
the
> people you first had. This is also a problem for you as a lot of
> people will not want to work to solve a problem that isn't going to
> happen until after they and their children are gone, they will try
to
> put it off to later.
>
> Next you will need a lot of infrastructure in space to do this and
> fast, so I'd be going over and digging out the plans for Orion. The
> Australian desert would be just about perfect for building and
> launching something like old bang-bang and it would just about put a
> fully built and working base into orbit. Fallout, I hear you say,
so
> what, soon it is going to a lot hotter than that.
>
> Massive mining of the solar system will give you all the raw
> materials you need so you shouldn't need to lift from deep gravity
> wells. That just leaves people to get from Earth. I'd be using a
> large Lightcraft and it's cousin that uses microwaves from orbit.
> Also do you need to take the whole person or just the eggs and
> sperm. Move as many people as you can and then germ plasm from as
> many others as possible to give you the maximum genetic variation.
>
> Bottom line, if you are evacuating then why bother to use a launch
> system as clean as a coil gun, you're not coming back and what is
> left is soon going to be toast, do whatever it takes.
>
> Of course if you are not in that situation you might want to
consider

bill t wrote:

>
> Actually, I came up with 1244 km, using 11.2km/s. The lowest I could
> convince myself was 500km.
>
> My scenerio moves less than 30% of the population, and it does assume
> a rather stringent population control.
>
> The putting it off for tommorrow was a basic assumption I said would
> not happen.
>
> The reason to move as many people off is more pyschological. If you
> start picking and choosing, those that know they will be left behind
> won't co-operate. Also I am trusting sheer numbers rather than the
> technological fix.
>
> Very few people know that 90% of all the colonists leaving England in
> the 17Th century never made it to their destination.
>
> The orions may be used to move a small initial population. But my
> scenerio is to evacuate the planet. To do that you need 75 launchers
> launching 1 capsule with 200 people in it every 20 minutes for 150
> years straight. There s no rocket system in the world that can compete
>
> with a launch system.
>
> If we were looking at today. To justify the cost of building the
> launcher you would need a project that needs to launch something daily
>
> or hourly. Lowering the final velocity is probably acceptable, and
> with your system we could get down to 350km. Depending on what you are
>
> launching you could increase the acceleration by a factor of 10, so we
>
> need 35km.
>
> The actual launcher would be sections of tube, so I could see the
> whole length being mass produced in a factory once the design is
> established and transported to its final position and hooked up. Then
> buried after the fact.
>
> I can't even think of putting together a construction cost for a
> minimal system, but launch costs as low as $10 a kg should be normal.
>
> What's a Lightcraft?
>
> Bill
>

Bill,

It's getting close to 1.00am so I'll make this short for now and give
you a more detailed post later. A lightcraft and it's cousin are
basically a simple idea. You take a really big laser and point it at
the base of your craft, the beam reflects from the base to heat the air
in a chamber, expands and pushes the capsule, repeat the cycle until you
run out of air and then if you still need thrust you let reaction mass
into the chamber which will keep pushing you. The microwave version
works with a power plant in orbit to beam power to you and reaction with
the craft and air gives you lift. The lightcraft (as a model) has flown
and an article in Scientific American (and others) provides detail. The
lightcraft could have a duty cycle that would rival a mass driver
(coilgun). Have a look at these links.

http://www-aero.meche.rpi.edu/curriculum/tavd/
http://www-aero.meche.rpi.edu/

Darren

bill t wrote:

Actually, I came up with 1244 km, using 11.2km/s. The lowest Icould
convince myself was 500km.
My scenerio moves less than 30% of the population, and it does assume
a rather stringent population control.
The putting it off for tommorrow was a basic assumption I said would
not happen.
The reason to move as many people off is more pyschological. Ifyou
start picking and choosing, those that know they will be left behind
won't co-operate. Also I am trusting sheer numbers rather thanthe
technological fix.
Very few people know that 90% of all the colonists leaving Englandin
the 17Th century never made it to their destination.
The orions may be used to move a small initial population. But my
scenerio is to evacuate the planet. To do that you need 75 launchers
launching 1 capsule with 200 people in it every 20 minutes for150
years straight. There s no rocket system in the world that cancompete
with a launch system.
If we were looking at today. To justify the cost of building the
launcher you would need a project that needs to launch somethingdaily
or hourly. Lowering the final velocity is probably acceptable,and
with your system we could get down to 350km. Depending on whatyou are
launching you could increase the acceleration by a factor of 10,so we
need 35km.
The actual launcher would be sections of tube, so I could see the
whole length being mass produced in a factory once the design is
established and transported to its final position and hooked up.Then
buried after the fact.
I can't even think of putting together a construction cost for a
minimal system, but launch costs as low as $10 a kg should be normal.
What's a Lightcraft?
Bill

Bill,
It's getting close to 1.00am so I'll make this short for nowand give you a more detailed post later. A lightcraft and it's cousinare basically a simple idea. You take a really big laser and pointit at the base of your craft, the beam reflects from the base to heat theair in a chamber, expands and pushes the capsule, repeat the cycle untilyou run out of air and then if you still need thrust you let reaction massinto the chamber which will keep pushing you. The microwave versionworks with a power plant in orbit to beam power to you and reaction withthe craft and air gives you lift. The lightcraft (as a model) hasflown and an article in Scientific American (and others) provides detail. The lightcraft could have a duty cycle that would rival a mass driver (coilgun). Have a look at these links.
http://www-aero.meche.rpi.edu/curriculum/tavd/
http://www-aero.meche.rpi.edu/

Darren