>The guy described a system of using a 100 Mw
>laser (cost: around $1 billion, dropping at 30% per year >in price
>currently) used to point at hydrogen >monopropellent vehicle the vehicle
>uses a heat exchanger >to boil the LH upto a relatively low temperature
>1000C >and then chucks it out through a conventional or aerospike nozzle.<<
>
>Am I correct that each launch throws away a billion
>dollar lasar? It seems like the laser should be made
>part of the returnable craft.
thinking of the same project that the speaker was describing.
I didn't realize though that the craft used liquid hydrogen, but not in
combustion. That at least is novel.
Still it's a little disappointing that, at the current yield, a $1 billion
laser can barely move two people to LEO.
--- In spacesettlers@y..., "Brad Walsh" wrote:
>
> >The guy described a system of using a 100 Mw
> >laser (cost: around $1 billion, dropping at 30% per year >in price
> >currently) used to point at hydrogen >monopropellent vehicle the
vehicle
> >uses a heat exchanger >to boil the LH upto a relatively low
temperature
> >1000C >and then chucks it out through a conventional or aerospike
nozzle.<<
> >
> >Am I correct that each launch throws away a billion
> >dollar lasar? It seems like the laser should be made
> >part of the returnable craft.
>
> No, the laser stays on the ground and fires up at the spacecraft,
if I'm
> thinking of the same project that the speaker was describing.
>
> I didn't realize though that the craft used liquid hydrogen, but
not in
> combustion. That at least is novel.
rich atmosphere, I can't imagine that combustion would _not_ occur;
whether that combustion would be controlled is a different matter
altogether.
:) ed
I seem to recall successful launches using a laser that heated normal air and the expansion of that air creating the thrust. The "vehicle looks like a thrust nozzle super polished on the interior and the laser aimed up inside.
Curious
Bob
SLF
-----
The Lightcraft Technology Incorporated site (c.f.,
http://www.lightcrafttechnologies.com/) may interest you.
******
"panamabob"
05/02/02 08:34 AM
Please respond to spacesettlers
To:
cc:
Subject: Re: [spacesettlers] Re: laser propulsion
I seem to recall successful launches using a laser that heated normal air
and the expansion of that air creating the thrust. The "vehicle looks like
a thrust nozzle super polished on the interior and the laser aimed up
inside.
As I said it already has launched successfully. Why complicate with
additional hydrogen? It would seem to defeat the concept of not requiring
the weight of fuel to be added to payload and hence additional costs.
Curious
Bob
SLF
-----
Yes the lightcraft folks are one and the same as I was writing about. Its seems at this point somewhat doable, why go for the hydrogen addition?
SLF
-----
The Lightcraft Technology Incorporated site (c.f.,
http://www.lightcrafttechnologies.com/) may interest you.
Ron
******
When launching a laser-heated craft using ambient air as propulsion, it
would seem that once you're out of the atmosphere, continued use of the
laser would only result in a hot man-made meteorite, unless the craft has a
gas of some sort stored on board to continue its thrust. And in the absence
of ambient air, the hydrogen would have no O2 to combust with.
>Subject: Re: [spacesettlers] Re: laser propulsion
>
>I seem to recall successful launches using a laser that heated normal air
>and the expansion of that air creating the thrust. The "vehicle looks like
>a thrust nozzle super polished on the interior and the laser aimed up
>inside.
>
>As I said it already has launched successfully. Why complicate with
>additional hydrogen? It would seem to defeat the concept of not requiring
>the weight of fuel to be added to payload and hence additional costs.
>
>Curious
>
>Bob
>SLF
> -----
>
http://www.hotmail.com
Hmm.? But to escape the atmosphere you will probably have been going pretty
and have built up decent momentum, yes? Also as atmosphere diminishes,
friction that slows you down will minimize as well, so perhaps the net
effect will be positive.
To:
Sent: Thursday, May 02, 2002 10:18 AM
Subject: Re: [spacesettlers] Re: laser propulsion
> When launching a laser-heated craft using ambient air as propulsion, it
> would seem that once you're out of the atmosphere, continued use of the
> laser would only result in a hot man-made meteorite, unless the craft has
a
> gas of some sort stored on board to continue its thrust. And in the
absence
> of ambient air, the hydrogen would have no O2 to combust with.
>
> Dad Astra
>
> >Subject: Re: [spacesettlers] Re: laser propulsion
> >
> >I seem to recall successful launches using a laser that heated normal air
> >and the expansion of that air creating the thrust. The "vehicle looks
like
> >a thrust nozzle super polished on the interior and the laser aimed up
> >inside.
> >
> >As I said it already has launched successfully. Why complicate with
> >additional hydrogen? It would seem to defeat the concept of not
requiring
Pure airbreathing vehicles cannot enter orbit. That particular
design is airbreathing, and as such is no use for that
application. The reason is due to orbital mechanics- orbits
necessarily intersect the last point where thrust occured.
For pure airbreathing vehicles this is within the atmosphere.
with it in some way.
Secondly, that design requires a pulsed laser. Pulsed lasers of
the relevant power are very expensive. The heat exchanger idea
does not require pulsed lasers. Cheap semiconductor lasers can
be ganged up and shone through telescopes at the vehicle from
several different locations.
Thirdly, with the system that was demoed the laser was shone
from below. To make orbit you must go sideways very fast, and
just a bit upwards. The angles are quite awkward- you have to
supply enough velocity before it goes over the horizon.
panamabob wrote:
> I seem to recall successful launches using a laser that heated normal air and the expansion of that air creating the thrust. The "vehicle looks like a thrust nozzle super polished on the interior and the laser aimed up inside.
>
> As I said it already has launched successfully. Why complicate with additional hydrogen? It would seem to defeat the concept of not requiring the weight of fuel to be added to payload and hence additional costs.
>
> Curious
>
> Bob
> SLF
> -----
>
--
- Ian Woollard (ian.woollard@...)
"Is a planetary surface the right place for an expanding
technological civilization?"
- Gerard O'Neill