# [ExI] keith's article at the oll drum

spike spike66 at att.net
Tue Jun 16 05:57:01 UTC 2009

```

> -----Original Message-----
> From: extropy-chat-bounces at lists.extropy.org
> [mailto:extropy-chat-bounces at lists.extropy.org] On Behalf Of spike
> Sent: Monday, June 15, 2009 7:36 AM
> To: 'ExI chat list'
> Subject: [ExI] keith's article at the oll drum
>
>
> Check it out:
>
> http://www.theoildrum.com/node/5485#more
>
> spike

Hey Keith, that is a really good article.  Thanks man, you have me thinking
again!  This motivates me to get with the program on those calculations for
getting a whole bunch of stuff to orbit.  I have been thinking of Jeff's
inflatable tower notion set on a mountain top with a linear induction motor
to get the payload to orbit.  The best I have been able to do so far is a
craft that is accelerated to perhaps a few hundred m/sec on a tower, then a
kerosene/lox winged first stage carries it to about 2500 meters per second,
releasing the payload at about 60 km altitude, at which time the lasers
start pushing like crazy.

The concept might be worth putting together a paper for SAWE.  If we need to
carry a whoooole buuunch of mass to orbit, then the tower and the laser
system are worth doing.  The task ahead is to calculate where is the break
even point.  I see the numbers in your article for mass, but it isn't clear
to me what size the panels can be.  For instance, can we launch them in two
meter  radius hexagons?  If so, can we get them to withstand about 5 G
launch load?  If so, how much weight would we add in holding them in place?
If we can get 5 G launch load, the tower goes to a reasonable height, and
material stresses down to modern capability.

Final word on linear induction motors.  There is a roller coaster at
Disneyland California Adventure that starts under linear induction.  It has
been a long time since I have been down there, but as I recall, the track
accelerates about 40 proles horizontally at about 1.5 G.  The part I vaguely
recall is that the track is water cooled, and after a launch steam was
coming off the track.  I might hafta look up the numbers on that.

spike

```