Coil guns vs. mass drivers

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