Space Solar Power – Recent Conceptual Progress
Keith Henson
About Skylon and laser propulsion to get the cost to GEO down.
http://www.theoildrum.com/node/7898
Keith Henson
Matt
classic SSTO problem: when you get into building actual hardware and
the design gets toward CDR, the payload mass faction drops rapidly to
zero. There has to be some technological breakthrough to make this
succeed in SSTO while being affordable to build, and I don't see it.
Matt Bille
www.mattwriter.com
======================================= MODERATOR'S COMMENT:
Permitted, but not sure actual goal of message?
Sylvia Else
> Skylon, cool as it is, has shown nothing to indicate it has solved the
> classic SSTO problem: when you get into building actual hardware and
> the design gets toward CDR, the payload mass faction drops rapidly to
> zero. There has to be some technological breakthrough to make this
> succeed in SSTO while being affordable to build, and I don't see it.
The breakthrough is the SABRE engine.
Sylvia.
neilzero
surface and/or in LEO to send lots of mass to GEO for space solar power.
These would worry a lot of people that they might be used for war etc.
The energy consumed by the laser stations would not be trivial. Perhaps
closer solar synchronous orbits are better as the rectennas or laser
light receiving sites could be much smaller and any where on Earth's
surface instead of only near the equator, and in the temperate zones.
Neil
--
neilzero
Jeff Findley
In article <328ad86a-128d-46d7-87ca-200c24fddd13
@k16g2000yqm.googlegroups.com>, MattW...@AOL.com says...
>
> Skylon, cool as it is, has shown nothing to indicate it has solved the
> classic SSTO problem: when you get into building actual hardware and
> the design gets toward CDR, the payload mass faction drops rapidly to
> zero. There has to be some technological breakthrough to make this
> succeed in SSTO while being affordable to build, and I don't see it.
To be fair, there have been some launch vehicle stages which have the
proper thrust and mass fraction. What they lack is the ability to
throttle their engines down to minimize G-loads and to make orbit before
they run out of fuel.
Henry Spencer has posted specific stages which meet the above criteria
in postings to these newsgroups. A Google search of these newsgroups
ought to turn up these postings. Of course, these stages were all
expendable. Making a reusable SSTO is quite a bit more difficult.
Jeff
--
" Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry
Spencer 1/28/2011
Jeff Findley
In article <96adhd...@mid.individual.net>, syl...@not.here.invalid
says...
>
>
Which has yet to be proven to work and has yet to fly on an operational
SSTO vehicle. Designing a vehicle to use SABRE could very well be more
difficult and expensive than developing the engine.
Steve Hix
Sylvia Else <syl...@not.here.invalid> wrote:
Has it gone past conceptualizing in any way at all?
Keith Henson
> Skylon, cool as it is, has shown nothing to indicate it has solved the
> classic SSTO problem: when you get into building actual hardware and
> the design gets toward CDR, the payload mass faction drops rapidly to
> zero. There has to be some technological breakthrough to make this
> succeed in SSTO while being affordable to build, and I don't see it.
>
> Matt Billewww.mattwriter.com
>
> Permitted, but not sure actual goal of message?
Matt, you missed the point of the article in The Oil Drum. It was not
about using the Skylon as a SSTO, but in suborbital mode to loft a 30
t second stage that gets to GEO using 9.8 km/s hydrogen heated by half
a GW of laser power.
And Sylvia got it right, the SABRE engine is a breakthrough. At best
rockets give 4.5 km/s exhaust velocity. If you back calculate the
Skylon at the end of atmospheric flight, it has the equivalent
performance of a rocket with a 10.5 km/s exhaust velocity.
The name of the game to get SSTO is high exhaust velocity. And since
you can't get that from chemical fuel, external heating is the only
game left.
Fortunately, high power laser diodes and very short microwaves have
recently come way down in cost and way up in power so it's possible to
start thinking about 6-10 km/s exhaust velocity.
Keith Henson
Sylvia Else
>
>
> In article<96adhd...@mid.individual.net>, syl...@not.here.invalid
>
> says...
>
>>
>
>> On 21/06/2011 7:55 AM, Matt wrote:
>
>>> Skylon, cool as it is, has shown nothing to indicate it has solved the
>
>>> classic SSTO problem: when you get into building actual hardware and
>
>>> the design gets toward CDR, the payload mass faction drops rapidly to
>
>>> zero. There has to be some technological breakthrough to make this
>
>>> succeed in SSTO while being affordable to build, and I don't see it.
>
>>
>
>> The breakthrough is the SABRE engine.
>
>
>
> Which has yet to be proven to work and has yet to fly on an operational
>
> SSTO vehicle. Designing a vehicle to use SABRE could very well be more
>
> difficult and expensive than developing the engine.
Nothing would ever get built if nothing was ever built before it had
been built.
On paper, Sabre has the characteristics required for an SSTO, and Skylon
itself isn't designed around unobtanium. So far no show stoppers have
been identified.
Sylvia.
Sylvia Else
Yes. Amongst other things, they're in the process of building a
prototype heat exchanger. They've developed and proved their frost
control technology. They've also been testing rocket nozzles.
Sylvia.
Keith Henson
> Keith Henson;1158169 Wrote:> About Skylon and laser propulsion to get the
cost to GEO down.
>
> >http://www.theoildrum.com/node/7898
>
> > Keith Henson
>
> A very large number of very powerful lasers are needed on Earth's
> surface and/or in LEO to send lots of mass to GEO for space solar power.
500 MW. 500 one MW lasers for a flow of 60 t/h starting from a
suborbital Skylon.
> These would worry a lot of people that they might be used for war etc.
That's correct. The particular design in that article has the lasers
going up to GEO to redirection/tracking mirrors that track the
accelerating vehicle along 7500 km of the equator. They point to
about a meter of accuracy.
If people still want to do wars, it is going to take new tactics when
there is a FOG (finger of God) overhead. Long as you don't have more
than one set of lasers and mirrors, then they are fixed in GEO and can
only hit targets on the half of the earth visible from a fixed spot at
GEO.
And, of course, anything in orbit.
> The energy consumed by the laser stations would not be trivial.
That's true, but all the transport energy is repaid in under two
months.
> Perhaps
> closer solar synchronous orbits are better as the rectennas or laser
> light receiving sites could be much smaller and any where on Earth's
> surface instead of only near the equator, and in the temperate zones.
I looked into this. The delta V needed to get to SSO is almost the
same as you need for GEO because of the plane change.
Keith Henson
> Neil
>
> --
> neilzero
Keith Henson
> In article <96adhdF91...@mid.individual.net>,
> Sylvia Else <syl...@not.here.invalid> wrote:
snip
> > The breakthrough is the SABRE engine.
>
> > Sylvia.
>
> Has it gone past conceptualizing in any way at all?
The hard part is the 2 GW heat exchanger. They have built and tested
sections of it.
Keith Henson
Jeff Findley
In article <sehix-CE5CD9....@5ad64b5e.bb.sky.com>,
se...@NOSPAMmac.comINVALID says...
>
> In article <96adhd...@mid.individual.net>,
> Sylvia Else <syl...@not.here.invalid> wrote:
>
> >
> >
> > Sylvia.
>
They've started building and testing pieces in the lab, but that's about
it. It's going to be a multi-billion dollar research and development
program for sure.
Keith Henson
snip
>
> Henry Spencer has posted specific stages which meet the above criteria
>
> in postings to these newsgroups. A Google search of these newsgroups
>
> ought to turn up these postings. Of course, these stages were all
>
> expendable. Making a reusable SSTO is quite a bit more difficult.
>
> Jeff
Taking "orbit" as 9,000 m/s and SSME as 4,500 m/s, the mass fraction
is 1/7.4 or 13.5%
Gary Hudson has informally said that a mass fraction of 15% is about
as low as you can go for "reusable."
Skylon C1 design was 17.8% structure, (and ~4% payload) but they
cheat. Counting the rotation of the earth, they get to 1/4 of orbital
speed with an equivalent exhaust velocity of 10.5 km/s.
I have a graph of beamed energy exhaust velocity vs cost if I can
figure out how to make it into something I can put on a wiki.
Keith
Jeff Findley
In article <96d8gu...@mid.individual.net>, syl...@not.here.invalid
says...
>
> Nothing would ever get built if nothing was ever built before it had
> been built.
>
> On paper, Sabre has the characteristics required for an SSTO, and Skylon
> itself isn't designed around unobtanium. So far no show stoppers have
> been identified.
On paper.
The show stoppers are the flight rate and reliability of bleeding edge
technologies. In order to make a profit (and pay off development
costs), Skylon will have to fly quite often and have an extremely high
reliability (hardware losses will be very expensive for such a complex
engine/vehicle).
A more conventional approach to reusable SSTO using VTVL and plain old
liquid fueled rocket engines would be a far more sane approach when you
take into account economics. That said, even SpaceX didn't use this
approach, instead choosing to build an expendable in order to minimize
development costs and time.
There are no existing markets which would require the high flight rates
needed to justify the development costs for Sabre and Skylon. It's a
research project which belongs in Popular Science magazine.
Keith Henson
> In article <96d8guF11...@mid.individual.net>, syl...@not.here.invalid
>
> says...
>
>
>
> > Nothing would ever get built if nothing was ever built before it had
> > been built.
>
> > On paper, Sabre has the characteristics required for an SSTO, and Skylo
n
> > itself isn't designed around unobtanium. So far no show stoppers have
> > been identified.
>
> On paper.
>
> The show stoppers are the flight rate and reliability of bleeding edge
>
> technologies. In order to make a profit (and pay off development
>
> costs), Skylon will have to fly quite often and have an extremely high
>
> reliability (hardware losses will be very expensive for such a complex
>
> engine/vehicle).
The engine doesn't have any more moving parts than a conventional
aircraft turbine. True, the vehicle is big, but not as heavy as a
747.
> A more conventional approach to reusable SSTO using VTVL and plain old
>
> liquid fueled rocket engines would be a far more sane approach when you
>
> take into account economics.
How do you get it back? If you put wings on it and land, then the
structure mass eats the whole mass budget.
> That said, even SpaceX didn't use this
>
> approach, instead choosing to build an expendable in order to minimize
>
> development costs and time.
>
> There are no existing markets which would require the high flight rates
>
> needed to justify the development costs for Sabre and Skylon.
I agree entirely with you statement. There is only one projected
market I know about where Skylon makes sense (SBSP) and even for that
market it takes something extreme for the second stage.
Power satellites really need $100/kg to GEO to make economic sense.
Keith
Jeff Findley
In article <01609aef-2c20-43b4-a553-9c84cb346892
@m3g2000pre.googlegroups.com>, hkeith...@gmail.com says...
>
> On Jul 12, 7:59 pm, Jeff Findley <jeff.find...@ugs.nojunk.com> wrote:
> > In article <96d8guF11...@mid.individual.net>, syl...@not.here.invalid
> >
> > says...
> >
> >
> >
> > > Nothing would ever get built if nothing was ever built before it had
> > > been built.
> >
> > > On paper, Sabre has the characteristics required for an SSTO, and Skylo
> n
> > > itself isn't designed around unobtanium. So far no show stoppers have
> > > been identified.
> >
> > On paper.
> >
> > The show stoppers are the flight rate and reliability of bleeding edge
> >
> > technologies. In order to make a profit (and pay off development
> >
> > costs), Skylon will have to fly quite often and have an extremely high
> >
> > reliability (hardware losses will be very expensive for such a complex
> >
> > engine/vehicle).
>
> The engine doesn't have any more moving parts than a conventional
> aircraft turbine. True, the vehicle is big, but not as heavy as a
> 747.
Development costs are still high and it's very unlikely that a Skylon
would have the high flight rate of a 747. The 747 needs that high
flight rate in order to justify the high development and operational
costs of its engines.
> > A more conventional approach to reusable SSTO using VTVL and plain old
> >
> > liquid fueled rocket engines would be a far more sane approach when you
> >
> > take into account economics.
>
> How do you get it back? If you put wings on it and land, then the
> structure mass eats the whole mass budget.
I said VTVL: vertical take off and vertical landing.
In other words, land the thing like DC-X on liquid fueled rocket engine
power and on vertical landing gear. This approach is simple (no wings
needed) and has been proven to work "in the real world".
> > That said, even SpaceX didn't use this
> >
> > approach, instead choosing to build an expendable in order to minimize
> >
> > development costs and time.
> >
> > There are no existing markets which would require the high flight rates
> >
> > needed to justify the development costs for Sabre and Skylon.
>
> I agree entirely with you statement. There is only one projected
> market I know about where Skylon makes sense (SBSP) and even for that
> market it takes something extreme for the second stage.
>
> Power satellites really need $100/kg to GEO to make economic sense.
Even then I'm not sure they make sense. They've got to compete with all
other alternative sources of terrestrial power. As fossil fuel prices
continue to rise, terrestrial alternatives become more attractive and
investment in them may yield reductions in cost such that space based
power never makes economic sense.
Keith Henson
> In article <01609aef-2c20-43b4-a553-9c84cb346892
>
> @m3g2000pre.googlegroups.com>, hkeithhen...@gmail.com says...
That's not entirely true. Nobody has ever gone to orbit with a DC-X
approach. It's possible new materials like carbon nanotubes or
graphene would get the structure fraction down far enough to have some
payload.
>
> > > That said, even SpaceX didn't use this
>
> > > approach, instead choosing to build an expendable in order to minimiz
e
>
> > > development costs and time.
>
> > > There are no existing markets which would require the high flight rat
es
>
> > > needed to justify the development costs for Sabre and Skylon.
>
> > I agree entirely with you statement. There is only one projected
> > market I know about where Skylon makes sense (SBSP) and even for that
> > market it takes something extreme for the second stage.
>
> > Power satellites really need $100/kg to GEO to make economic sense.
>
> Even then I'm not sure they make sense. They've got to compete with al
l
>
> other alternative sources of terrestrial power. As fossil fuel prices
>
> continue to rise, terrestrial alternatives become more attractive and
>
> investment in them may yield reductions in cost such that space based
>
> power never makes economic sense.
That's possible. But it will take a conceptually different approach,
like solar collectors that grow themselves like Kudzu. It seems
unlikely that earth based solar power will ever get down to 2 cents
per kWh, and that's the target I set for power satellites.
(StratoSolar might be an exception.)
Keith
Jeff Findley
In article <41f2ea4f-47ee-4f68-b980-399f7e714df0
@j14g2000prn.googlegroups.com>, hkeith...@gmail.com says...
>
> On Jul 14, 7:26 pm, Jeff Findley <jeff.find...@ugs.nojunk.com> wrote:
> > In article <01609aef-2c20-43b4-a553-9c84cb346892
> >
> > Even then I'm not sure they make sense. They've got to compete with
> > all other alternative sources of terrestrial power. As fossil fuel
> > prices continue to rise, terrestrial alternatives become more
> > attractive and investment in them may yield reductions in cost such
> > that space based power never makes economic sense.
>
> That's possible. But it will take a conceptually different approach,
> like solar collectors that grow themselves like Kudzu. It seems
> unlikely that earth based solar power will ever get down to 2 cents
> per kWh, and that's the target I set for power satellites.
> (StratoSolar might be an exception.)
Perhaps advances similar to this?
Photovoltaic Breakthroughs Brighten Outlook for Cheap Solar Power
Novel materials might make harvesting sunlight for electricity
affordable
http://www.scientificamerican.com/article.cfm?id=photovoltaic-
breakthroughs-brighten-outlook-for-cheap-solar-power
And there are always other renewable sources, like wind, wave,
hydroelectric, thermal, and etc.
Keith Henson
> In article <41f2ea4f-47ee-4f68-b980-399f7e714df0
>
> @j14g2000prn.googlegroups.com>, hkeithhen...@gmail.com says...
>
>
>
> > On Jul 14, 7:26 pm, Jeff Findley <jeff.find...@ugs.nojunk.com> wrote:
> > > In article <01609aef-2c20-43b4-a553-9c84cb346892
>
> > > Even then I'm not sure they make sense. They've got to compete wit
h
> > > all other alternative sources of terrestrial power. As fossil fuel
> > > prices continue to rise, terrestrial alternatives become more
> > > attractive and investment in them may yield reductions in cost such
> > > that space based power never makes economic sense.
>
> > That's possible. But it will take a conceptually different approach,
> > like solar collectors that grow themselves like Kudzu. It seems
> > unlikely that earth based solar power will ever get down to 2 cents
> > per kWh, and that's the target I set for power satellites.
> > (StratoSolar might be an exception.)
>
> Perhaps advances similar to this?
>
> Photovoltaic Breakthroughs Brighten Outlook for Cheap Solar Power
>
> Novel materials might make harvesting sunlight for electricity
>
> affordable
>
>
> breakthroughs-brighten-outlook-for-cheap-solar-power
Frankly, no. This is not particularly reliable information. Shame
too, I grew up on Scientific American, started reading it in 1957,
read back issues to 1948 and read every issue till the editorial
policy changed and it got "fluffy."
> And there are always other renewable sources, like wind, wave,
>
> hydroelectric, thermal, and etc.
Wind will not scale large enough, wave is much worse. Hydroelectric
is mostly exploited. Geothermal isn't large enough either.
You might want to look here: Sustainable Energy — Without the Hot
Air. http://en.wikipedia.org/wiki/David_J._C._MacKay It's available
online.
Keith