> At 04:34 4/18/98 EDT, you wrote:
> >
> >The tubes could have gills in them, like in front of the craft the gills are
> >open, so it wont create compressed air in front of it (or not as much), since
> >it will escape into the outside air, and as the craft passes over the gills
> >they become temporarily sealed to hold the seal-tight air bursts behind the
> >craft, then they would have to be opened again for the next craft after the
> >first craft passes the next charging station.
> >The gills would have to be like super thin and lightweight (but still able to
> >be sealed), so it wont create very much friction for the craft. Where and
> >when to get out have to be worked out, like perhaps the tubes split, and they
> >are diverted in a station, so it wont hold up the crafts behind it as they
> >pass through.
> >
> >danny
>
> This sounds like something that could be tried with a fairly low investment
> = a couple of big shop vacuums and some large tubing. Perhaps we could build
> a scale model for experimenting??
>
> As far as shunting aside - there are existing diverter valves for pneumatic
> mail delivery systems that could be tried...
>
> I still am worried about frictional losses. All pneumatic systems lose a
> good deal of energy due to compression heating of the working fluid..
Yes, however using electromagnetically actuated cylinders along the route to
evacuate ahead of the projectile and pump right behind the projectile will help
alleviate this by a goodly amount. Using this method, you not only reduce drag,
but you use it to generate thrust. Another measure would be to use ionization
effects to minimize shock wave formation along the boundary between the projectile
and the tube wall.
Of course, any tube system IMHO is not economically cost effective unless you have
a really high population density along the corridor being served, with large
population centers at each end. While Japan might be a good place to develop
these, the US doesn't currently have the need, as there is still plenty of air
capacity to be used, especially with decentralized GPS navigation beign phased in.
Mass transit, at this point in time and in the near future is not a cost effective
investment of resources. Current mass transit projects here in the US average an
investment of $300,000.00-750,000.00 per new mass transit system user. They are
subsidized by large numbers of people who live very far from the systems and never
or rarely use them, or even need them. In comparison, any public agency can
reduce transit/highway system use (thus reducing pollution, energy consumption,
and road traffic) by investing in home workstations and training for unemployed
people who are dislocated by economic shifts, often for less than $10,000 per
person. Mass transit requires the construction of very dense communities at
selected stations to be of any use for large areas on long routes (a long route is
the only situation where an vacuum tube system would be of any use.) The trend in
the US here is in less dense communities...
The Seattle Rail Transit system proposed several years ago, for example, proposed
spending $9 billion to increase mass transit ridership by a mere 34,000 people.
In the same time period, they projected that as much as 8 percent of the total
workforce in the area would shift to telecommuting at a cost to the taxpayer of
$0.00. Hmmmmm, which is the more useful thing to promote???
-- TANSTAAFL!!! Michael Lorrey ------------------------------------------------------------ mailto:retroman@together.net Inventor of the Lorrey Drive MikeySoft: Graphic Design/Animation/Publishing/Engineering ------------------------------------------------------------ How many fnords did you see before breakfast today?