"SpaceShipTwo could be single stage to SUBorbit"

On 5/11/2010 10:42 AM, Robert Clark wrote:

On May 10, 3:24 pm, Bob Myers wrote:



On 5/10/2010 12:47 PM, Robert Clark wrote:



If you also filled up the passenger compartment with fuel leaving only a pilot's cabin could it even become orbital?



Even if it could, the next question would be how you'd plan on DE-orbiting in a survivable manner... Bob M.



True you would also have to add on the weight of thermal protection for reentry from orbital speeds.


Or just add on another whole heapin' helpin' of fuel....;-)

Damn, people, this IS the 21st century now, after all - aren't we supposed
to have, by now, the equivalent of the Star Trek shuttlecraft, that can basically
thumb its nose at gravity and come down as quickly or slowly as you want?
I'm even more disappointed that I can't yet go out and buy a Jetsons-type
Rosie the Robot or a flying car that folds up into a briefcase once I get to
work.

Bob M.


Bob M.

On Tue, 11 May 2010 09:23:45 -0700, Robert Clark wrote:

On May 10, 2:47Â*pm, Robert Clark wrote:
Â*Interesting article he

snip


If Virgin Galactic really is serious about this then I foresee
passenger orbital flights proceeding quite apace!

a) You're replying to your own post?

b) Space ship 2 goes about 4,200 km/hour * 1 hour/3600 sec = 1.2 km/s(1).
LEO is about 9.3-10 km/s. Energy wise, the ratio of spaceship 2 to a LEO
capable vehicle would be (1.2/9.3)^2 = 0.017. From there, it gets worse
once you consider re-entry (need a way to dissipate 60x the energy), the
rocket equation (the faster your delta V, the worse your rocket mass
ratio) and so on.

These plastic things are toys of the pompously named "Virgin Galactic"
are meant to look impressive, but they are very far away from LEO. Very
far. Their appeal is to give much undeserved astronauts wings to rich
people who don't have anything better to do with their money.


(1) http://en.wikipedia.org/wiki/SpaceShipTwo
(2) http://en.wikipedia.org/wiki/Delta_v

In sci.space.history Marvin the Martian wrote:
These plastic things are toys of the pompously named "Virgin
Galactic" are meant to look impressive, but they are very far away
from LEO. Very far. Their appeal is to give much undeserved
astronauts wings to rich people who don't have anything better to do
with their money.

I take it you aren't all that impressed with barnstorming either?

rick jones
--
The glass is neither half-empty nor half-full. The glass has a leak.
The real question is "Can it be patched?"
these opinions are mine, all mine; HP might not want them anyway...
feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH...

On May 12, 4:41*am, Pat Flannery wrote:
On 5/11/2010 4:57 AM, Jeff Findley wrote:



SpaceShipTwo is designed to fly high, not fast. *You need both to make it
into orbit.

One gets the feeling with SpaceShipTwo that if they could have kept the
fight upwards subsonic, they would have gone for it.
I still like that loopy idea to shoot the X-15 into orbit atop some sort
of rocket booster, and have it reenter and crash into the Gulf of
Mexico, with the pilot ejecting on the way down:http://www.astronautix.com/craft/x15b.htm

Thanks for that. Hadn't heard of that one before.

Bob Clark

On 5/11/2010 4:57 AM, Jeff Findley wrote:


SpaceShipTwo is designed to fly high, not fast. You need both to make it
into orbit.

One gets the feeling with SpaceShipTwo that if they could have kept the
fight upwards subsonic, they would have gone for it.
I still like that loopy idea to shoot the X-15 into orbit atop some sort
of rocket booster, and have it reenter and crash into the Gulf of
Mexico, with the pilot ejecting on the way down:
http://www.astronautix.com/craft/x15b.htm
I'm sure a lot of pilots would have lined up for that mission.
"Pressure suit?"
"Check."
"Space helmet?"
"Check".
"Parachute?"
"Check."
"Shark repellent?"
"Uh, now wait a minute." ;-)

Pat

On 5/11/2010 12:17 PM, Bob Myers wrote:
On 5/11/2010 6:57 AM, Jeff Findley wrote:

Actually, ignorant can be fixed. Stupid can't. In most cases, it's easy
enough to explain that orbital velocity is so fast that you really do
need a
huge amount of fuel and oxidizer to get into orbit. The X-15 example
helps
somewhat too. The X-15 could fly high or fast, but could not do both
on the
same mission. And even the X-15's high speed flights only achieved a
small
fraction of orbital velocity.

It would seem we need an explanation akin to something Douglas Adams
might have written - you know, comparable to "Space is big. You just won't
believe how vastly, hugely, mind- bogglingly big it is. I mean, you may
think
it's a long way down the road to the chemist's, but that's just peanuts
to space."

However, I seem to recall that there was an idea, part of the old Air
Force "Man In Space, Soonest" proposals, that did involve basically
strapping on some additional boost to an X-15 and getting the thing into
orbit, no? Not sure how they were planning on dealing with the "getting
it back down" problem, either...


They did one X-15 test flight with a spray-on ablative TPS coating that
was supposed to be easily cleaned off and replaced after the flight.
What the pilots thought of this, as the aircraft was now pink*, has not
been recorded.
After the flight they found the ablative coating had cooked itself right
on to the skin of the aircraft and was almost impossible to remove, so
the concept was dropped.

* I keep picturing it covered in pencil eraser rubber:
http://www.dfrc.nasa.gov/gallery/pho...l/ECN-1736.jpg

Pat

On 5/11/2010 12:20 PM, Bob Myers wrote:

thumb its nose at gravity and come down as quickly or slowly as you want?
I'm even more disappointed that I can't yet go out and buy a Jetsons-type
Rosie the Robot or a flying car that folds up into a briefcase once I get to
work.

But things are much more futuristic for cats, as Scott Lowther found on
YouTube: http://www.youtube.com/watch?v=LQ-jv8g1YVI
You just know that sooner or later the tail is going to go under the
Roomba, and then the cat will never try that again.
Here kittens find out about inertia:
http://www.youtube.com/watch?v=GTxW3...eature=related
That must be some fun house - kittens, toddler, robot, dog.
It's like some sort of bachelor's nightmare coming true. :-)

Pat

On 5/12/2010 5:13 AM, Pat Flannery wrote:
On 5/11/2010 12:17 PM, Bob Myers wrote:
On 5/11/2010 6:57 AM, Jeff Findley wrote:

Actually, ignorant can be fixed. Stupid can't. In most cases, it's easy
enough to explain that orbital velocity is so fast that you really do
need a
huge amount of fuel and oxidizer to get into orbit. The X-15 example
helps
somewhat too. The X-15 could fly high or fast, but could not do both
on the
same mission. And even the X-15's high speed flights only achieved a
small
fraction of orbital velocity.

It would seem we need an explanation akin to something Douglas Adams
might have written - you know, comparable to "Space is big. You just
won't
believe how vastly, hugely, mind- bogglingly big it is. I mean, you may
think
it's a long way down the road to the chemist's, but that's just peanuts
to space."

However, I seem to recall that there was an idea, part of the old Air
Force "Man In Space, Soonest" proposals, that did involve basically
strapping on some additional boost to an X-15 and getting the thing into
orbit, no? Not sure how they were planning on dealing with the "getting
it back down" problem, either...


They did one X-15 test flight with a spray-on ablative TPS coating that
was supposed to be easily cleaned off and replaced after the flight.
What the pilots thought of this, as the aircraft was now pink*, has not
been recorded.
After the flight they found the ablative coating had cooked itself right
on to the skin of the aircraft and was almost impossible to remove, so
the concept was dropped.

* I keep picturing it covered in pencil eraser rubber:
http://www.dfrc.nasa.gov/gallery/pho...l/ECN-1736.jpg

That X-15 is in the Air Force Museum, with ablative coating still in
place. The best laid plans . . .

But that's why they flew such things on X-planes instead of just putting
them in service without a flight test. Now if they'd done that for the
Shuttle's thermal tiles . . .

There was indeed a plan to strap a bunch of solid rockets to an X-15 and
put it in orbit, with a heat shield. The Powers That Be decided that
humans couldn't function under the stresses of space flight though and
went with a fully automated "capsule". Would be a different world if
the X-15B had been flown and worked.

On May 10, 2:47*pm, Robert Clark wrote:
*Interesting article he

SpaceShipTwo could be single stage to suborbit says ESA firm.
By Rob Coppinger
on April 29, 2010 4:24 PM
"Virgin Galactic's SpaceShipTwo could be a single stage to suborbit
vehicle using liquid chemical propulsion according to independent
research carried out by a company that has been contracted by the
European Space Agency for suborbital and hypersonic transport
studies."
"... the UK firm came to the conclusion that the volume within which
SS2 carries its solid rocket motor and nitrous oxide supply could
equally hold a liquid chemical propulsion system capable of providing
enough thrust for long enough for a horizontal take-off and ascent to
50,000ft and above without the need for WK2."http://www.flightglobal.com/blogs/hyperbola/2010/04/spaceshiptwo-coul...

If you also filled up the passenger compartment with fuel leaving only
a pilot's cabin could it even become orbital?


The usefulness of just using a single stage for the suborbital flights
is to save on costs. Using two vehicles would cost twice as much to
develop and twice as much in per flight costs.
Note that XCOR is the leading suborbital tourism venture after Virgin
Galactic. They plan to take off with a single craft from the ground
rather than using a two-stage system. The reason they can do this is
because they are using a higher performance liquid-fueled engine
rather than VG's hybrids. Note, also they will charge $100,000 for the
suborbital flight, half of what VG is charging.

Bob Clark

XCOR Lynx suborbital vehicle animation.
http://www.youtube.com/watch?v=3a-l1tb1rPg

On May 10, 2:47*pm, Robert Clark wrote:
*Interesting article he

SpaceShipTwo could be single stage to suborbit says ESA firm.
By Rob Coppinger
on April 29, 2010 4:24 PM
"Virgin Galactic's SpaceShipTwo could be a single stage to suborbit
vehicle using liquid chemical propulsion according to independent
research carried out by a company that has been contracted by the
European Space Agency for suborbital and hypersonic transport
studies."
"... the UK firm came to the conclusion that the volume within which
SS2 carries its solid rocket motor and nitrous oxide supply could
equally hold a liquid chemical propulsion system capable of providing
enough thrust for long enough for a horizontal take-off and ascent to
50,000ft and above without the need for WK2."http://www.flightglobal.com/blogs/hyperbola/2010/04/spaceshiptwo-coul...

If you also filled up the passenger compartment with fuel leaving only
a pilot's cabin could it even become orbital?


Take a look at this diagram to get an idea of the volume you could
fill with propellant for SS2:

SpaceShipOne and SpaceShipTwo comparison.
http://a52.g.akamaitech.net/f/52/827...shiptwo_02.jpg

It's a roughly cylindrical space about 40 feet long. Divide this by
3.28 to get the length in meters, 12.2 meters. You could estimate the
diameter also from this diagram but this page gives the fuselage
diameter as 2.28 meters:

SpaceShipTwo - Wikipedia, the free encyclopedia.
http://en.wikipedia.org/wiki/SpaceShipTwo

Then the cylindrical volume is PI*(radius^2)*length =
(3.1416)*(1.14^2)*12.2 = 49.8 m^3. Take the overall density of kero/
LOX propellant as 1030 kg/m^3. Then this amounts to a propellant mass
of 51,300 kg.
The fuselage does taper off towards the end so you should get a more
accurate estimate by modeling this volume as a conical frustum:

Conical Frustum.
http://mathworld.wolfram.com/ConicalFrustum.html

The question is what is the dry mass of SpaceShipTwo?


Bob Clark