Re: Mass Drivers and Cheap Space Access: Limits

From: Michael S. Lorrey (
Date: Sun Apr 16 2000 - 19:44:32 MDT

Spike Jones wrote:
> Robert J. Bradbury wrote:
> > >From this URL:
> >
> >
> > It goes on to discuss how you could engineer methods to allow humans
> > to tolerate higher G forces.
> Robert Im thinking we could emerse the astronauts for a half a minute
> in water during launch, at which time they could take 40 g for 12 seconds
> plus about 15 negative g for about another few seconds as they decelerated
> out of the atmosphere. The track length would need to be about 29 km
> and the velocity left over after atmopheric deceleration would still
> amount to ~4 km/sec at which time rockets would need to take
> over to accelerate to orbital velocity.
> The emersion technique would probably not be comfortable but
> I think it would be survivable. spike

These are possible systems. A local company, Creare, is doing
hyperoxidized fluid breathing system research (as seen in the movie _The
Abyss_) for the Air Force. The difficulty with this technology is
getting people to be at all useful once they've 'drowned'. It typically
requires some serious training to keep the people from having serious
panic attacks that retain some PTSD effects afterward. Now, the G limits
are definitely something that is only necessary if your occupants are
going to be actively involved in the piloting of the vehicle, which is
not necessary. The I think 13 g limits the Air Force uses are measures
of intermittent g tolerance to retain conciousness. Automated piloting
obviates the need for concious occupants.

If you are using rockets after exiting the tube, are you not countering
the negative 15 g's somewhat? Additionally, could you not use the laser
propulsion system to fire some bursts ahead of the vehicle prior to
exiting the tube to cause the air to expand outward due to thermal
shock, temporarily creating a bit of a vacuum tube in the air? If this
were possible you'd get less drag induced decelleration, though I'm sure
you'd need some good 3d thermal imaging to plot it out to prevent it
from adding to turbulence...

This archive was generated by hypermail 2b29 : Thu Jul 27 2000 - 14:09:23 MDT