Why is a LOX/Kero SSTO not rather easy?

[Larry Gales]

I am not a particular fan of SSTO, but it appears to me that SSTO has
long been within our grasp.

The best figures that I could get for the Titan II 1st stage
(based on Rusty Barton's reply to my earlier post) are a
GLOW 0f 258000 lbs, and a dry weight of 10900, giving it a mass ratio of
23.7. Now comparing it to a LOX/kero vehicle powered by something like
the Russian NK-33, I see the following plus and minus factors affecting
its mass ratio (I am not including a payload in these calculations):

On the minus side, the Titan II 1st stage is not a complete vehicle. It:

(a) lacks a nose cone
(b) lacks most avionics
(c) lacks a cargo bay
(d) has 6% denser fuel so a slightly smaller fuel tank

On the plus side:
(a) the NK-33 is 420 lbs lighter than the Titan II engine
yet it is sufficient for a vehicle nearly 10% heavier
(b) the structure does not have to support the 32 ton 2nd stage
and so can be significantly lighter.

My guess is that those factors mostly cancel out. I also assume that
making a vehicle reusable adds about 40% to its dry weight:
Wings add 7%
Landing gear add 3%
TPS add 15%
Other add 15%

So if we crank those factors in:
Dry weight = 10900*1.4 = 15300 lbs
Glow = 258000 + (15300 - 10900) = 262400
MR = GLOW/(GLOW-Dry weight) = 262400/15300 = 17.15

Now for the NK-33 we have an average Isp of 331, and given a required
dV of 9200 m/s (300 m/s less than a LH2/LOX rocket due to less air
resistance, lower back pressure losses, and earlier peak acceleration)
we get a required MR of 17.01, which is slightly less than what we
can achieve. So we can make orbit with a single stage using very old
technology.

Of course, this is without payload, but given the fact that the Titan II
1st stage was not optimized for weight (you would not normally optimize a
1st stage) and we have lighter materials today, such as aluminum-lithium
and carbon fiber, I would think we would have the necessary margin
for a significant payload.

We also might fly with a wet wing and eliminate the kerosene tank
altogether. And of course if we scaled it up by a factor of 3
we would gain a substantial economy of scale.

So it appears to me that we have had reusable SSTO capability for
dense fuel vehicles for a long time.

-- Larry

[Robert Kitzmüller]

Hi Larry!

Well, I'd like to add a few nitpicks. I removed a lot of the text where
I do not disagree.

Larry Gales wrote:
[...]
> My guess is that those factors mostly cancel out. I also assume that
> making a vehicle reusable adds about 40% to its dry weight:
> Wings add 7%
> Landing gear add 3%
> TPS add 15%
> Other add 15%

I do not think wings could be done for only 7% of the weight, especially
if one takes into account the added structure needed for a winged
vehicle. However I am partial to wingless vehicle and I did the following
calculations: The spaceship has in the earth a terminal velocity of
50...100 m/s (example: cw=1, 10 m diameter, 50t weight => 60m/s)
Say you want 200m/s fuel including reserves, so you would need 6-7%
mass depending on Isp - and the engines and structure needed are already
there.

Question: which items do you include among "other"? I see only
restfuel and a bit more avionics, but this should not amount to 15%.
However, I might easily miss something...

> So if we crank those factors in:
> Dry weight = 10900*1.4 = 15300 lbs
> Glow = 258000 + (15300 - 10900) = 262400
> MR = GLOW/(GLOW-Dry weight) = 262400/15300 = 17.15
>
> Now for the NK-33 we have an average Isp of 331, and given a required
> dV of 9200 m/s (300 m/s less than a LH2/LOX rocket due to less air
> resistance, lower back pressure losses, and earlier peak acceleration)
> we get a required MR of 17.01, which is slightly less than what we
> can achieve. So we can make orbit with a single stage using very old
> technology.

I notice most modern rockets are more "fat" than Titan. However, I am
not sure how much weight could be saved if the tanks have more diameter
and less length, and there is some delta-V loss due to additional air
resistance. Additional advantage to the fat version: I want a lot of
drag for breaking during descend.

> Of course, this is without payload, but given the fact that the Titan
> II 1st stage was not optimized for weight (you would not normally
> optimize a 1st stage) and we have lighter materials today, such as
> aluminum-lithium and carbon fiber, I would think we would have the
> necessary margin for a significant payload.

You can optimize a RLV a bit more than a ELV: increased construction
costs for the airframe would be spread over a high number of flights.
However, initially you would *have* to keep down development costs,
so this might not be possible for the first generation.

> We also might fly with a wet wing and eliminate the kerosene tank
> altogether. And of course if we scaled it up by a factor of 3
> we would gain a substantial economy of scale.

As before: I think you underestimate the weight of a wing.

> So it appears to me that we have had reusable SSTO capability for
> dense fuel vehicles for a long time.

Well, I agree. I just do not think a winged vehicle would be the way to
go.

Robert Kitzmueller

[Larry Gales]

On Tue, 2 Sep 2003, Robert Kitzm=FCller wrote:

> Date: Tue, 02 Sep 2003 18:49:47 +0200
> From: "Robert [ISO-8859-1] Kitzm=FCller" >
> Newsgroups: sci.space.policy, sci.space.tech
> Followup-To: sci.space.policy
> Subject: Re: Why is a LOX/Kero SSTO not rather easy?
>
> Hi Larry!
>
> Well, I'd like to add a few nitpicks. I removed a lot of the text where
> I do not disagree.
>
> Larry Gales wrote:
> [...][i]
> > My guess is that those factors mostly cancel out. I also assume that
> > making a vehicle reusable adds about 40% to its dry weight:
> > Wings add 7%
> > Landing gear add 3%
> > TPS add 15%
> > Other add 15%
>
> I do not think wings could be done for only 7% of the weight, especially
> if one takes into account the added structure needed for a winged
> vehicle. However I am partial to wingless vehicle and I did the following
> calculations: The spaceship has in the earth a terminal velocity of
> 50...100 m/s (example: cw=3D1, 10 m diameter, 50t weight =3D> 60m/s)
> Say you want 200m/s fuel including reserves, so you would need 6-7%
> mass depending on Isp - and the engines and structure needed are already
> there.
>
> Question: which items do you include among "other"? I see only
> restfuel and a bit more avionics, but this should not amount to 15%.
> However, I might easily miss something...

--------------------------------------------------

I am not wedded to the idea of a winged vehicle, and Henry Spencer also
thought that wings would be more than 7%.

What I would like to see is an annular aerospike for the engine for it
not only provides superior ISP but would also act as a heat shield and
would simpilfy landing as you could use but a few nozzles rather than
having to throttle large engines down.

Also all the stresses would be along the same line and in the same
direction throughout the flight making strucutre easier and lighter.

-- Larry

[Robert Kitzmüller]

Larry Gales wrote:
> What I would like to see is an annular aerospike for the engine for it
> not only provides superior ISP but would also act as a heat shield and
> would simpilfy landing as you could use but a few nozzles rather than
> having to throttle large engines down.

It certainly looks like a workable concept. However, aerospikes were
never used for propulsion, neither for ELV nor RLV, so there might be
unknown problems. I see possible problems also in the aerospike
exhaust flow if there are only a few chambers (of a whole lot)
used: It will spread to the sides, and it might become turbulent.
(I say might, since I am not to sure about this. Has anybody ever looked
at this closely?)

> Also all the stresses would be along the same line and in the same
> direction throughout the flight making strucutre easier and lighter.
>
This would be the main attraction of a base-reentry base-landing RLV.

[Earl Colby Pottinger]

Larry Gales > :

> Yes. The only useful thing that might have come out of the X33 was
> whether or not aerospikes would work throughout the flight path -- but we
> never did learn that. In fact did we learn *anything* from the X33 other
> than that the approach was a big mistake?

As far as I can tell, zero useful information was learnt from X-33 while over
a billion dollars was spent.

A cheap aluminium rocket could have been built to test the aerospikes - it
was not done because it was not a high tech enough way to doing the test.

A cheap solid fuel rocket (Orbital?) could have been used to test the
metallic TPS - again it was not done because it was not a high tech enough
way to doing the test.

A small scale tank could have been built and tested a hundred times with fill
and empty cycle and the problem found, or they could have given the contract
to someone who does know something about composite tanks like Scaled
Composite - but thier ego demanded building full scale tanks before they did
all the needed tests.

Doing it the low tech way probably would have cost less money than was spent
and would have given us good test data on two of the three techonologies.

Earl Colby Pottinger

--
I make public email sent to me! Hydrogen Peroxide Rockets, OpenBeos,
SerialTransfer 3.0, RAMDISK, BoatBuilding, DIY TabletPC. What happened to
the time? http://webhome.idirect.com/~earlcp

[Joann Evans]

Larry Gales wrote:
>
> On Fri, 5 Sep 2003, Robert Kitzmüller wrote:
>
> > Date: Fri, 05 Sep 2003 17:48:06 +0200
> > From: "Robert [ISO-8859-1] Kitzmüller" >
> > Newsgroups: sci.space.policy
> > Subject: Re: Why is a LOX/Kero SSTO not rather easy?
> >
> > Larry Gales wrote:[i]
> > > What I would like to see is an annular aerospike for the engine for it
> > > not only provides superior ISP but would also act as a heat shield and
> > > would simpilfy landing as you could use but a few nozzles rather than
> > > having to throttle large engines down.
> >
> > It certainly looks like a workable concept. However, aerospikes were
> > never used for propulsion, neither for ELV nor RLV, so there might be
> > unknown problems. I see possible problems also in the aerospike
> > exhaust flow if there are only a few chambers (of a whole lot)
> > used: It will spread to the sides, and it might become turbulent.
> > (I say might, since I am not to sure about this. Has anybody ever looked
> > at this closely?)
> -------------------------
> Yes. The only useful thing that might have come out of the X33 was
> whether or not aerospikes would work throughout the flight path -- but we
> never did learn that. In fact did we learn *anything* from the X33 other
> than that the approach was a big mistake?
> ----------------------------------
>
> -- Larry
>
> >
> > > Also all the stresses would be along the same line and in the same
> > > direction throughout the flight making strucutre easier and lighter.
> > >
> > This would be the main attraction of a base-reentry base-landing RLV.
> >


There was some *cold* flow data on the SR-71 mounted scaled-down
engine (the H2 leaked too much to fire LASRE in flight, if I understand
correctly), and plenty of hot firings of a static engine. Also, some
good work on more robust, weather-resistant (from samples tested on an
F-15 flying under various conditions) thermal protective materials.

But yeah, that, and how *not* to make a composite tank, were about
all we really got out of it....

[Rusty B]

Earl Colby Pottinger > wrote in message >...
> Larry Gales > :
>
> > Yes. The only useful thing that might have come out of the X33 was
> > whether or not aerospikes would work throughout the flight path -- but we
> > never did learn that. In fact did we learn *anything* from the X33 other
> > than that the approach was a big mistake?
>
> As far as I can tell, zero useful information was learnt from X-33 while over
> a billion dollars was spent.
>


Are you trying to tell us that something stinks at the Skunkworks? ;-)



-Rusty

[Len]

(Rusty B) wrote in message >...
> Earl Colby Pottinger > wrote in message >...
> > Larry Gales > :
> >
> > > Yes. The only useful thing that might have come out of the X33 was
> > > whether or not aerospikes would work throughout the flight path -- but we
> > > never did learn that. In fact did we learn *anything* from the X33 other
> > > than that the approach was a big mistake?
> >
> > As far as I can tell, zero useful information was learnt from X-33 while over
> > a billion dollars was spent.
> >
>
>
> Are you trying to tell us that something stinks at the Skunkworks? ;-)
>
If it's a high profile, high-cost program like the X-33,
then it ain't a skunkworks. The Skunkworks--when it
existed--was not a place, it was a way of doing business.
As Norm Nelson (Kelly's succesor) used to say: "You have
to get the project done, before the hyenas find out about
it."

Best regards,
Len (Cormier)
PanAero, Inc. and Third Millennium Aerospace, Inc.
( http://www.tour2space.com )
>
>
> -Rusty

[Michael Walsh]

Len wrote:

> (Rusty B) wrote in message >...
> > Earl Colby Pottinger > wrote in message >...
> > > Larry Gales > :
> > >
> > > > Yes. The only useful thing that might have come out of the X33 was
> > > > whether or not aerospikes would work throughout the flight path -- but we
> > > > never did learn that. In fact did we learn *anything* from the X33 other
> > > > than that the approach was a big mistake?
> > >
> > > As far as I can tell, zero useful information was learnt from X-33 while over
> > > a billion dollars was spent.
> > >
> >
> >
> > Are you trying to tell us that something stinks at the Skunkworks? ;-)
> >
> If it's a high profile, high-cost program like the X-33,
> then it ain't a skunkworks. The Skunkworks--when it
> existed--was not a place, it was a way of doing business.
> As Norm Nelson (Kelly's succesor) used to say: "You have
> to get the project done, before the hyenas find out about
> it."
>
> Best regards,
> Len (Cormier)
> PanAero, Inc. and Third Millennium Aerospace, Inc.
> ( http://www.tour2space.com )
> >
> >
> > -Rusty

From everything I have read lately, the only relationship that
the recent Lockheed-Martin "Skunkworks" has with the old
one formed by Kelly Johnson is the name.

The demise of the X-33 is much more a result of bad
management than either technical failure
(composite LH2 tanks) or even a bad selection of
the winning X-33 concept.

Mike Walsh

[Rand Simberg]

On Mon, 15 Sep 2003 00:39:01 GMT, in a place far, far away, Michael
Walsh > made the phosphor on my monitor glow in
such a way as to indicate that:

>The demise of the X-33 is much more a result of bad
>management than either technical failure
>(composite LH2 tanks) or even a bad selection of
>the winning X-33 concept.

I disagree. The selection was awful, on a number of counts as (I
don't hesitate to point out) I pointed out at the time.

--
simberg.interglobal.org * 310 372-7963 (CA) 307 739-1296 (Jackson Hole)
interglobal space lines * 307 733-1715 (Fax) http://www.interglobal.org

"Extraordinary launch vehicles require extraordinary markets..."
Swap the first . and @ and throw out the ".trash" to email me.
Here's my email address for autospammers:

[jeff findley]

(Rand Simberg) writes:
>
> On Mon, 15 Sep 2003 00:39:01 GMT, in a place far, far away, Michael
> Walsh > made the phosphor on my monitor glow in
> such a way as to indicate that:
>
> >The demise of the X-33 is much more a result of bad
> >management than either technical failure
> >(composite LH2 tanks) or even a bad selection of
> >the winning X-33 concept.
>
> I disagree. The selection was awful, on a number of counts as (I
> don't hesitate to point out) I pointed out at the time.

I remember those times. There was a lot of disgust that NASA picked
the winner with the coolest new technology to explore. Instead, it
would have been nice to pick the winner based on which was most likely
to successfully fly, which would have meant picking the winner with
the least amount of new technology.

Case in point, there was little to no new technology in DC-X. It's
point was to prove that you could design, build, and fly a
"spacecraft" for far less than NASA cost models. On top of that, it
was to show rapid turn-around for LH2/LOX engines and vertical takeoff
and landings without requiring a huge ground infrastructure
(e.g. purpose built launch and landing pads).

Jeff
--
Remove "no" and "spam" from email address to reply.
If it says "This is not spam!", it's surely a lie.

[Rand Simberg]

On 15 Sep 2003 11:08:58 -0400, in a place far, far away, jeff findley
> made the phosphor on my monitor glow
in such a way as to indicate that:

(Rand Simberg) writes:
>>
>> On Mon, 15 Sep 2003 00:39:01 GMT, in a place far, far away, Michael
>> Walsh > made the phosphor on my monitor glow in
>> such a way as to indicate that:
>>
>> >The demise of the X-33 is much more a result of bad
>> >management than either technical failure
>> >(composite LH2 tanks) or even a bad selection of
>> >the winning X-33 concept.
>>
>> I disagree. The selection was awful, on a number of counts as (I
>> don't hesitate to point out) I pointed out at the time.
>
>I remember those times. There was a lot of disgust that NASA picked
>the winner with the coolest new technology to explore. Instead, it
>would have been nice to pick the winner based on which was most likely
>to successfully fly, which would have meant picking the winner with
>the least amount of new technology.

They also picked a contractor that clearly had no intention whatsoever
of building a commercial launch system with its own money.

--
simberg.interglobal.org * 310 372-7963 (CA) 307 739-1296 (Jackson Hole)
interglobal space lines * 307 733-1715 (Fax) http://www.interglobal.org

"Extraordinary launch vehicles require extraordinary markets..."
Swap the first . and @ and throw out the ".trash" to email me.
Here's my email address for autospammers:

[Michael Walsh]

Rand Simberg wrote:

> On Mon, 15 Sep 2003 00:39:01 GMT, in a place far, far away, Michael
> Walsh > made the phosphor on my monitor glow in
> such a way as to indicate that:
>
> >The demise of the X-33 is much more a result of bad
> >management than either technical failure
> >(composite LH2 tanks) or even a bad selection of
> >the winning X-33 concept.
>
> I disagree. The selection was awful, on a number of counts as (I
> don't hesitate to point out) I pointed out at the time.

I would have preferred the then McDonnell-Douglas concept myself
and the North American design would have been a lower risk concept.

However, when a contractor identifies something as the highest
risk part of the program (the conformal, composite LH2 tanks) and
then marches on to failure then I have to feel that type of management
would have resulted in failure with any selected concept.

Of course, since any other selected concept would have had different
management that is an argument for the importance of the concept
selection.

Mike Walsh

[Michael Walsh]

Rand Simberg wrote:

> On 15 Sep 2003 11:08:58 -0400, in a place far, far away, jeff findley
> > made the phosphor on my monitor glow
> in such a way as to indicate that:
>
> (Rand Simberg) writes:
> >>
> >> On Mon, 15 Sep 2003 00:39:01 GMT, in a place far, far away, Michael
> >> Walsh > made the phosphor on my monitor glow in
> >> such a way as to indicate that:
> >>
> >> >The demise of the X-33 is much more a result of bad
> >> >management than either technical failure
> >> >(composite LH2 tanks) or even a bad selection of
> >> >the winning X-33 concept.
> >>
> >> I disagree. The selection was awful, on a number of counts as (I
> >> don't hesitate to point out) I pointed out at the time.
> >
> >I remember those times. There was a lot of disgust that NASA picked
> >the winner with the coolest new technology to explore. Instead, it
> >would have been nice to pick the winner based on which was most likely
> >to successfully fly, which would have meant picking the winner with
> >the least amount of new technology.
>
> They also picked a contractor that clearly had no intention whatsoever
> of building a commercial launch system with its own money.

I believe that was true of all of the contractors.

I can also make an argument that the way NASA structured the
competition there was no possible way this could have been
accomplished.

Mike Walsh

[Rand Simberg]

On Tue, 16 Sep 2003 01:11:26 GMT, in a place far, far away, Michael
Walsh > made the phosphor on my monitor glow in
such a way as to indicate that:

>> They also picked a contractor that clearly had no intention whatsoever
>> of building a commercial launch system with its own money.
>
>I believe that was true of all of the contractors.

It may have been, but it was *obviously* true of Lockmart, simply
based on their joke of a business plan.

>I can also make an argument that the way NASA structured the
>competition there was no possible way this could have been
>accomplished.

That may be true as well.

--
simberg.interglobal.org * 310 372-7963 (CA) 307 739-1296 (Jackson Hole)
interglobal space lines * 307 733-1715 (Fax) http://www.interglobal.org

"Extraordinary launch vehicles require extraordinary markets..."
Swap the first . and @ and throw out the ".trash" to email me.
Here's my email address for autospammers:

[Allen Thomson]

(Rand Simberg) wrote


> It may have been, but it was *obviously* true of Lockmart, simply based on their joke of a business plan.

Are any details about that plan available yet? Last I heard, a couple
of years ago, NASA and LockMart were being reticent when asked for it.

[Rand Simberg]

On 16 Sep 2003 10:42:03 -0700, in a place far, far away,
(Allen Thomson) made the phosphor on my monitor
glow in such a way as to indicate that:

(Rand Simberg) wrote
>
>> It may have been, but it was *obviously* true of Lockmart, simply based on their joke of a business plan.
>
>Are any details about that plan available yet? Last I heard, a couple
>of years ago, NASA and LockMart were being reticent when asked for it.

I've never seen details, but unless it differed a great deal from the
general presentations that I saw from people like Jerry Rising, it was
a joke, and not a funny one. Only someone unfamiliar with credible
business plans (e.g., NASA) would have been fooled by it.

--
simberg.interglobal.org * 310 372-7963 (CA) 307 739-1296 (Jackson Hole)
interglobal space lines * 307 733-1715 (Fax) http://www.interglobal.org

"Extraordinary launch vehicles require extraordinary markets..."
Swap the first . and @ and throw out the ".trash" to email me.
Here's my email address for autospammers:

[Allen Thomson]

(Rand Simberg) wrote

> I've never seen details, but unless it differed a great deal from the
> general presentations that I saw from people like Jerry Rising, it was
> a joke, and not a funny one. Only someone unfamiliar with credible
> business plans (e.g., NASA) would have been fooled by it.

Not that I have much sympathy for LockMart, but the mind-boggling
thing was that NASA made having a "business plan" a requirement
for the bid on what started out as an available-technology SSTO
RLV demonstrator and wound up as a technology development sandbox.

[Rand Simberg]

On 16 Sep 2003 18:54:46 -0700, in a place far, far away,
(Allen Thomson) made the phosphor on my monitor
glow in such a way as to indicate that:

(Rand Simberg) wrote
>
>> I've never seen details, but unless it differed a great deal from the
>> general presentations that I saw from people like Jerry Rising, it was
>> a joke, and not a funny one. Only someone unfamiliar with credible
>> business plans (e.g., NASA) would have been fooled by it.
>
>Not that I have much sympathy for LockMart, but the mind-boggling
>thing was that NASA made having a "business plan" a requirement
>for the bid on what started out as an available-technology SSTO
>RLV demonstrator and wound up as a technology development sandbox.

Yes, the whole program was mind boggling.

--
simberg.interglobal.org * 310 372-7963 (CA) 307 739-1296 (Jackson Hole)
interglobal space lines * 307 733-1715 (Fax) http://www.interglobal.org

"Extraordinary launch vehicles require extraordinary markets..."
Swap the first . and @ and throw out the ".trash" to email me.
Here's my email address for autospammers: