Less difficult than Skylon - Spacebus?

Einar wrote:
Sylvia Else wrote:
wrote:
There has been some talk on the Skylon SSTO proposal. But there
exchist some potential alternatives, like this airlaunch sceme:

http://www.bristolspaceplanes.com/pr...spacebus.shtml


At least nothing sounds impossible. Fewer expensive to develope new
technologies than in the Skylon proposal.

Cheers, Einar

The orbiter looks as if it would have a higher ballistic coefficient
than Skylon, which means that its skin will reach a higher temperature
during reentry, which in turn impacts on the skin material. The space
shuttle's skin is so fragile that it has to be inspected in detail after
every flight, which is a significant part of the time and cost of
turning it around.

I'm unclear as to why the orbiter has a delta wing if it's not itself
going to be flying during launch. An orbiter that does not fly during
reentry until reaching subsonic speed is perfectly feasible.

Turning around the space bus looks like it would involve using a crane
to put the orbiter back onto the first stage.

Sylvia.

For Skylon the big uncertain technology appears to be the engine. That
one will probably take years of development. After all, it will be
pretty groundbraking if it works the way they hope it will.

A good description of the project on Wiki: http://en.wikipedia.org/wiki/Skylon

Cheers, Einar


There's much more detail on Reaction Engines' own site.

http://www.reactionengines.co.uk/

Sylvia Else wrote:
wrote:
There has been some talk on the Skylon SSTO proposal. But there
exchist some potential alternatives, like this airlaunch sceme:

http://www.bristolspaceplanes.com/pr...spacebus.shtml


At least nothing sounds impossible. Fewer expensive to develope new
technologies than in the Skylon proposal.

Cheers, Einar


There appears to be nothing there but a few numbers and an artist's
impression.

Sylvia.

That is true, at the moment they are developing the ascender, that is
if what is said on that page can be trusted. Mind you, the Skylon is
perhaps being computer modelled, and they are trying to develope the
engine. That alone may take several years, after all that engine
really sounds a bit challenging. After all it intends to use a fan,
but fanblades tend to melt beyond mac 2.5, which they appear to be
trying to solve by cooling the airflow. It might work, then it might
not. They appear though to have built a prototype of that airflow
cooling device.

If the engine doesn´t work, that´s a project killer.

By the way, thanks for posting theyr site. I´ll bookmark it for future
study.

Cheers, Einar

Einar wrote:
Sylvia Else wrote:
wrote:
There has been some talk on the Skylon SSTO proposal. But there
exchist some potential alternatives, like this airlaunch sceme:

http://www.bristolspaceplanes.com/pr...spacebus.shtml


At least nothing sounds impossible. Fewer expensive to develope new
technologies than in the Skylon proposal.

Cheers, Einar

There appears to be nothing there but a few numbers and an artist's
impression.

Sylvia.

That is true, at the moment they are developing the ascender, that is
if what is said on that page can be trusted. Mind you, the Skylon is
perhaps being computer modelled, and they are trying to develope the
engine. That alone may take several years, after all that engine
really sounds a bit challenging. After all it intends to use a fan,
but fanblades tend to melt beyond mac 2.5, which they appear to be
trying to solve by cooling the airflow. It might work, then it might
not. They appear though to have built a prototype of that airflow
cooling device.

I think the motivation for cooling the airflow is to get it into a state
that's suitable for use as the oxidiser in a rocket engine, rather than
to avoid having the turbocompressor melt, though the latter is obviously
a plus.


If the engine doesn´t work, that´s a project killer.

That's true, and I'm sure that's the reason they're working intially on
the engine.

Sylvia.

Derek Lyons wrote:
wrote:

There has been some talk on the Skylon SSTO proposal. But there
exchist some potential alternatives, like this airlaunch sceme:

Let's just put it this way; air launch is a solution in search of a
problem.

D.
--
Touch-twice life. Eat. Drink. Laugh.

-Resolved: To be more temperate in my postings.
Oct 5th, 2004 JDL

The specific problem they have in mind solving with that idea is
passenger flight into space. I don´t know about you, but I find it
likelly that well off passengers would be put off by the idea to climb
into something which is sitting vertically on a launchpad.

Cheers, Einar

"Derek Lyons" wrote in message
...
wrote:

There has been some talk on the Skylon SSTO proposal. But there
exchist some potential alternatives, like this airlaunch sceme:

Let's just put it this way; air launch is a solution in search of a
problem.

Eh, I have to disagree. I think they have their place. They allow you to
launch at a favorable lattitude and azimuth.

It's not a win for every case, but I think it has its place.



D.
--
Touch-twice life. Eat. Drink. Laugh.

-Resolved: To be more temperate in my postings.
Oct 5th, 2004 JDL

--
Greg Moore
SQL Server DBA Consulting Remote and Onsite available!
Email: sql (at) greenms.com http://www.greenms.com/sqlserver.html

Sylvia Else wrote:

Derek Lyons wrote:
wrote:

There has been some talk on the Skylon SSTO proposal. But there
exchist some potential alternatives, like this airlaunch sceme:

Let's just put it this way; air launch is a solution in search of a
problem.

D.

That's not reasonable. We have the problem identified - getting into
space cheaply.

Why is it not reasonable? Air launched spacecraft have nothing to do
with getting to orbit cheaply.

D.
--
Touch-twice life. Eat. Drink. Laugh.

-Resolved: To be more temperate in my postings.
Oct 5th, 2004 JDL

Derek Lyons wrote:
Sylvia Else wrote:

Derek Lyons wrote:
wrote:

There has been some talk on the Skylon SSTO proposal. But there
exchist some potential alternatives, like this airlaunch sceme:
Let's just put it this way; air launch is a solution in search of a
problem.

D.
That's not reasonable. We have the problem identified - getting into
space cheaply.

Why is it not reasonable? Air launched spacecraft have nothing to do
with getting to orbit cheaply.

D.

You may have doubts about whether they can do so, but that doesn't make
them a solution looking for a problem. They might be a proposed solution
that doesn't work, but that's something else entirely.

Sylvia.

Derek Lyons wrote:
Sylvia Else wrote:


Why is it not reasonable? Air launched spacecraft have nothing to do
with getting to orbit cheaply.

D.
--
Touch-twice life. Eat. Drink. Laugh.

-Resolved: To be more temperate in my postings.
Oct 5th, 2004 JDL


That´s an assertion without obvious reasoning behind it.

Mind you, the carrier plane ought to able to ensure that there is
allways a launch in fair weather. In addition, nossle designs of the
orbiter can be optimized as there will be no reason to design them to
be efficient beneath the highaltitude environment.

The carryer plane probably will be more expensive to operate than a
conventional aeroplana. The orbiter undoubtedly will have some
operational expenses too. In this case the carryer plane is probably
the greatest uncertainty, as it´s something which has never so far
exchisted a large hypersonic plane. However, if this particular plane
is too difficult they may fall back to the less ambitious plane that
was only planned to do mac 4, mac 2 on jets over to rocket powered mac
4, with a smaller orbiter carrying smaller paload to orbit. There is
no reason whatsoever to believe that the less ambitious version wouldn
´t work. The more ambitious would be then perhaps be for later
development when the other has proven to work.


Cheers, Einar

"Sylvia Else" wrote in message
...
Derek Lyons wrote:
Sylvia Else wrote:

Derek Lyons wrote:
wrote:

There has been some talk on the Skylon SSTO proposal. But there
exchist some potential alternatives, like this airlaunch sceme:
Let's just put it this way; air launch is a solution in search of a
problem.

D.
That's not reasonable. We have the problem identified - getting into
space cheaply.

Why is it not reasonable? Air launched spacecraft have nothing to do
with getting to orbit cheaply.

D.

You may have doubts about whether they can do so, but that doesn't make
them a solution looking for a problem. They might be a proposed solution
that doesn't work, but that's something else entirely.

We have doubts because air breathing launch vehicle stages such as these
won't be cheap and easy to build. Hypersonic aircraft are still bleeding
edge technology.

These things are roughly reminiscent of the XB-70, and it's been a long time
since anyone flew something as big and fast as an XB-70. That and the XB-70
didn't fly anywhere near Mach 6 or demonstrate successful separation of an
upper stage at that speed. Look up info on the D-21/M-21 crash and you'll
find one more reason why such an approach isn't as easy as it seems.

http://www.designation-systems.net/dusrm/app4/d-21.html

Jeff
--
"They that can give up essential liberty to obtain a
little temporary safety deserve neither liberty nor
safety"
- B. Franklin, Bartlett's Familiar Quotations (1919)

"Einar" wrote in message
ups.com...

The carryer plane probably will be more expensive to operate than a
conventional aeroplana. The orbiter undoubtedly will have some
operational expenses too. In this case the carryer plane is probably
the greatest uncertainty, as it´s something which has never so far
exchisted a large hypersonic plane. However, if this particular plane
is too difficult they may fall back to the less ambitious plane that
was only planned to do mac 4, mac 2 on jets over to rocket powered mac
4, with a smaller orbiter carrying smaller paload to orbit. There is
no reason whatsoever to believe that the less ambitious version wouldn
´t work. The more ambitious would be then perhaps be for later
development when the other has proven to work.

I can think of one good reason:

http://www.designation-systems.net/dusrm/app4/d-21.html

Jeff
--
"They that can give up essential liberty to obtain a
little temporary safety deserve neither liberty nor
safety"
- B. Franklin, Bartlett's Familiar Quotations (1919)