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The 100/10/1 Rule.



 
 
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  #141  
Old March 19th 07, 01:05 AM posted to sci.space.history,sci.space.policy,sci.space.station,sci.space.shuttle
Henry Spencer
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Posts: 2,170
Default fun with expendable SSTOs (was The 100/10/1 Rule.)

In article ,
Rand Simberg wrote:
Unfortunately, I'm not going to make Space Access this year, to my great
annoyance, so the talk won't appear. Deadline problems.


We'll be sorry to miss you, Henry. Is this unprecedented?


Yep, first time I've missed one, and I'm sorry about it too. I really
thought I could make it -- had hotel and plane reservations -- but I've
been ill lately (nothing dire but it's really slowed me down), and a big
hard deadline is coming up. In theory I could attend and still make the
deadline... if nothing goes wrong... but my colleagues on this project
have been very patient with me, and I owe it to them to leave a reasonable
safety margin, and it just wasn't there. Rats.

And I think you're wasting your time with Craig. He's got the true
religion.


Once in a while I'll sally forth against the heathens :-) just to make
sure that their claims don't go unchallenged in public. A few of the
worst cases I just don't bother with any more, in the interests of my
blood pressure :-), but Craig hasn't reached that point, yet.
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |
  #143  
Old March 19th 07, 03:35 AM posted to sci.space.history,sci.space.policy,sci.space.station,sci.space.shuttle
Henry Spencer
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Posts: 2,170
Default fun with expendable SSTOs (was The 100/10/1 Rule.)

In article ,
john hare wrote:
If I ever get started again, I have business reasons for a continuing
interest in some airbreathing cruise. If my business model matches
reality closely enough, The mass penalties will be acceptable. If
I get money, it will most likely come from pilot/businessmen. If
we ever fly, it will probably have to be from airports that have not
done the paperwork to become spaceports.


If you have reason for wanting a period of low-speed cruise after takeoff
or before landing, *then* airbreathing can make considerable sense, since
cruise (as opposed to acceleration) is something rockets are not good at.
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |
  #144  
Old March 19th 07, 06:12 AM posted to sci.space.history,sci.space.policy,sci.space.station,sci.space.shuttle
Pat Flannery
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Default fun with expendable SSTOs (was The 100/10/1 Rule.)



John Schilling wrote:

Propane may be slightly better as a launcher fuel, but it's a cryogen
(albiet a soft one), which makes it much worse as a missile fuel. As
most everyone who has ever built a space launch vehicle has also been
in the missile-building business as well, they've understandably gone
and standardized on kerosene as their hydrocarbon fuel of choice.


How about butane?
It stays liquid at ambient temperature at far lower pressures than propane.
Refill butane for lighters comes in pressure vessels not much
thicker-skinned than beer cans.

Pat

  #145  
Old March 19th 07, 06:24 AM posted to sci.space.history,sci.space.policy,sci.space.station,sci.space.shuttle
Henry Spencer
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Posts: 2,170
Default fun with expendable SSTOs (was The 100/10/1 Rule.)

In article ,
Pat Flannery wrote:
Propane may be slightly better as a launcher fuel, but it's a cryogen
(albiet a soft one), which makes it much worse as a missile fuel...


How about butane?
It stays liquid at ambient temperature at far lower pressures than propane.


Pure butane in fact has a vapor pressure of about 31psi, which is perhaps
a bit higher than you'd like but not too bad. However, at room
temperature it may not have much of an advantage over kerosene, which is
certainly easier yet to handle. And unlike propane, it doesn't stay
liquid at LOX temperatures, a property that has some appeal. (Note that,
as John said, for *launchers*, the fact that propane is a soft cryogen is
not a significant problem.)
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |
  #146  
Old March 19th 07, 01:41 PM posted to sci.space.history,sci.space.policy,sci.space.station,sci.space.shuttle
[email protected]
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Posts: 1,516
Default fun with expendable SSTOs (was The 100/10/1 Rule.)

On Mar 19, 12:12�am, Pat Flannery wrote:
John Schilling wrote:

Propane may be slightly better as a launcher fuel, but it's a cryogen
(albiet a soft one), which makes it much worse as a missile fuel. *As
most everyone who has ever built a space launch vehicle has also been
in the missile-building business as well, they've understandably gone
and standardized on kerosene as their hydrocarbon fuel of choice.


How about butane?
It stays liquid at ambient temperature at far lower pressures than propane.
Refill butane for lighters comes in pressure vessels not much
thicker-skinned than beer cans.

Pat



  #147  
Old March 19th 07, 03:22 PM posted to sci.space.history,sci.space.policy,sci.space.station,sci.space.shuttle
Craig Fink
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Posts: 1,858
Default fun with expendable SSTOs (was The 100/10/1 Rule.)

Yeah, water might be acceptable, but adding energy too is probably better.

From your posting, you still don't get it yet. Extrapolating results of
studies between this and than to a third thing can lead to false
conclusions. It's dangerous to extrapolate outside the useful range of some
trade study and the thumb rule may not apply. Is it the Hydrogen or the
fact that the Saturn V tank must support the payload above, big tank
supporting big payload weighs more than small tank supporting big payload.
Better take that into account, OK, don't support any weight with the big
tank. Well, that's good for exo-atmospheric SSTOs with rockets, they don't
have any payload, problem solved.

Reaction time, Hydrogen shines here too.

Time in nozzle, you didn't notice I said plug somewhere in there. A plug
after the throat keeps the flow in the nozzle at a much slower supersonic
speed. Therefore, just past the throat the jerk isn't so large. The Mach
number and pressure where the bypass (not so high pressure) hydrogen or
oxygen is added is also chosen. The flow is manipulated to keep it slow,
giving more reaction time.

Pipe, the pipe is just to deliver the not so high pressure liquids past the
throat. The input end is very near the turbines too, nice. The Christmas
Tree attached to the pipe is non-trivial, hence all the fun Trade Studies
to figure out the how to do it right. A Trade Study of how to optimize it,
with lots of variable.

I've been giving you and everybody else hints the whole time. Hydrogen, so
much energy in such a small package?

Hydrogen, 1, fuel
Oxygen, 16, oxidizer
Carbon, 12, dense liquid fuel
Aluminum, 27, even more dense typical solid type fuel
Iron, 56, and even more dense

Opportunity missed, yeah I started talking about dumping in denser fuels
then switched over to lighter fuels. Even hit return before noticing (a
little bit later) I forgot to switch the rich mixtures. Which rich mixture
is exiting the throat. Surprise, no I it didn't just discover that the rich
mixtures should have been switch. Fixed the backflow, but not the Thrust,
instead of fixing both. You could have simply done that too, opportunity
missed.

Hard to beat a Mixture Ratio range of 16 for Hydrogen and Oxygen. Allowing
for widest variation along the Thrust/ISP curve. High Thrust/Low ISP on the
Oxygen side, Low Thrust/High ISP on the Hydrogen side. Just what an SSTO
needs, High Thrust Early with ISP continously climbing as best it can, all
the way to the Space Station. Oxygen/Carbon is only 1.33, Iron/Oxygen 3.5.
Not even close to the potential of Oxygen/Hydrogen.

So much energy at the optimal mixture ratio it's just too hot to burn
completely. Premixed, half burnt, Oxygen/Hydrogen exiting the throat, some
of it combining in the nozzle and some wasted, exiting the nozzle unburnt.
Yeah, so adding water isn't that bad an idea to make sure all the Hydrogen
and Oxygen are also water before exiting the nozzle.

Water, 18, propellent
Argon, 40, heavier propellent
Xenon, 131, even heavier propellent

Wow, exhaust propellent mass ratio range of 7.2 Xenon/Water. Hello ... Air
Liquide ... Hi, how are you today ... Yes, I'd like to order a half million
gallons of Xenon per month, and could you give me a price on that ...
Ahhh ... Ahhh ... Ahhh, better make that Argon(2.2) ... Hold on, let me
think about it ... Nitrogen(1.5) ... Oxygen(1.78) ... Carbon
Dioxide(2.44) ... Ahhh, yes that will do, and how much are the delivery
charges to Mars ... What? ... Ahhh, thanks for your help but, I think I'll
just liquefy my own when I get there.

HOTOL???, How not to fly in the Atmosphere to Orbit, yeah, yeah, I agree.
This and that, negative outcome, yep. Only reason to build HOTOL is to do
it, gain experience, fine tune models, spark imagination, research
platform, improve the state of the art, find the next step, walk a little
further. Just studying it just isn't quite the same.

I still think it's better to take some payload with an SSTO in the
Atmosphere. ;-)
--
Craig Fink
Courtesy E-Mail Welcome @
--

Henry Spencer wrote:

In article nk.net,
Craig Fink wrote:
What should the mass be? Well, since the engine is already running on the
extreme Oxygen rich side, probably any old heavy dense liquid that reacts
well with Oxygen would do. Since pressures are lower in the bell, maybe
even a pressure fed tank might work...


If you're injecting into the supersonic flow, you might as well just use
water. There won't be *time* for any significant reaction; the exhaust is
moving *fast* at that point, and accelerating fiercely, and it just
doesn't stay in the nozzle for long. The usual rule of thumb is that
reaction rates even in the already-mixed combustion gases are effectively
zero after the throat.

Even just reasonable mixing -- which is what's needed if you want to bulk
out the exhaust this way -- is doubtful with just a straight pipe. You
need some kind of atomization, even if it's only plugging the end of the
pipe and drilling a bunch of holes in its side just above the end.

Some kind of non-trivial injector discharging into the chamber will work a
lot better. At which point, of course, you can start thinking about how
much hydrogen and how much dense fuel is appropriate. Interestingly
enough, you might find that the percentage of hydrogen keeps going down as
you analyze more carefully. Surprise, you've just discovered that dense
fuels are better for SSTOs than hydrogen...

I still think Atmospheric Flight to Orbit is the way to go, I kind of like
the extra payload to Orbit.


Odd that people who actually study this in detail quite consistently find
that it gives less payload to orbit. (E.g., the HOTOL team found that
going all-rocket, with other assumptions left unchanged, would more than
double their payload. Same story as dense fuels vs. hydrogen: lower Isp,
but also much lighter hardware bringing the mass ratio way up.)



  #148  
Old March 19th 07, 06:11 PM posted to sci.space.history,sci.space.policy,sci.space.station,sci.space.shuttle
Craig Fink
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Posts: 1,858
Default fun with expendable SSTOs (was The 100/10/1 Rule.)

john hare wrote:

"Henry Spencer" wrote in message
...
In article . net,
Craig Fink wrote:

...I bring up "Fluid
Variable Intakes" which fits nicely with his engine and invalidating
certain assumptions of his trade study. His study just swung in a
different
direction.


I don't believe you explained what "Fluid Variable Intakes" are. *It's
not a term I'm familiar with either, although I don't keep up with the
current fads :-) on the airbreathing side.


I don't keep up with the fads to much either. To be honest, I just made the
term up. I thought it best described what it was, a "Fluid Variable
Intake", sounds good to me. If it's not really a physical cooler (cooling
really just a bonus) and not really a physical inlet, and it's variable,
what is it? The concept, I made that up too. It also sounded good to me, it
would essentially let a slightly modified jet aircraft fly straight up exit
the atmosphere at Mach 5, winning the X-Prize. But, like I said, it's hard
to find a good used engine/supersonic "non-government developed" aircraft
these days.

If you have a better name, or know of a different name that it goes by, let
me know. It would be fun reading about it.

It would have needed negative mass to counteract the engine weight
to a degree necessary to match pure rocket stage performance.
I lost interest somewhat in supersonic intakes when it became
clear that there could not be a cost advantage to them.


Someone's selling tickets for short zero gee trips in a modified commercial
airliner for probably $1000, someone else is selling tickets in supersonic
aircraft for $10,000-$20,000, and someone else will soon be selling long
zero gee trips in custom designed rocket planes for $200,000. There is a
whole lot of room between $1000-$20,000 and $200,000 to sell tickets for
long zero gee trips in turbojet/rocket powered aircraft.
  #149  
Old March 20th 07, 01:15 PM posted to sci.space.history,sci.space.policy,sci.space.station,sci.space.shuttle
Craig Fink
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Posts: 1,858
Default Fluid Variable Intakes ( fun with expendable SSTOs ...)

Fluid Variable Intakes

For Acceleration type mission profiles with Turbojet, Ramjet, and Scramjet.
Fluid Variable Intakes fix many of the difficult problems associated with
these engines, making it possible to use a single fixed inlets or a much
less complex inlet. As the aircraft passes the maximum design Mach Number
for the inlet, a fluid is used to compensate for the changing area ratio
between the beginning of the inlet and the sonic throat. Cryogenic Oxygen /
Gaseous Oxygen being the fluid, also enriches the air taken in by the
engine with Oxygen, enhancing the performance when it is needed to continue
to accelerating.

It reduces the complexity of the associated inlet hardware, replace complex
mechanical moving aerodynamic surfaces with a fluid distribution system.
It's also possible to preheat the Cryogenic Oxygen to gasify it at a
relatively high pressure to dynamically bring throat to sonic conditions,
reducing the Oxygen flow rate. This allows the Oxygen flow rate to be
regulated to maintain engine operating conditions, statically added mass
(dumping) vs dynamically added mass (thrusting) Oxygen in the inlet.

It cools the air, radically reducing compressor inlet temperatures.

Since Oxygen flow rate is related to Mach number, performance is maintained
as the aircraft continues to climb and accelerate. Essentially, it slowly
converts the engine from an airbreather into a rocket smoothly varying the
performance during acceleration from an Specific Fuel Consumption (ISP in
rocket terms) greater than 2000 down to something less than 500 at the end
of the acceleration.

Normally for turbojets the added Oxygen would be a problem for turbine inlet
temperatures. But this can be compensated for by changing the mixture ratio
in the combustion chamber. Switching from a fuel lean mixture ratio
combustion usually used for endurance/range type missions, to a fuel rich
mixture. Essentially going over the high temperature hump, to an extremely
fuel rich condition. This also adds mass flow through the turbine, spinning
the compressor and turbine up.

The fuel rich turbine exhaust can then be mixed with the bypass air as an
afterburner. The bypass air also enriched with Oxygen. Hydrogen, with
double the energy per weight of any other fuel would probably be the best
fuel for such an acceleration type mission. It also would simplify
combustion, ensuring complete combustion.

Fluid Variable Intakes smoothly transition an airbreathing engine into a
rocket engine and allows an aircraft continue accelerating quite a bit
past what would normally be considered it's maximum speed.

Probably not very useful for endurance/range type mission, but extremely
useful for acceleration type mission, and going to Orbit in the Atmosphere.

--
Craig Fink
Courtesy E-Mail Welcome @
--

Henry Spencer wrote:

I don't believe you explained what "Fluid Variable Intakes" are. *It's not
a term I'm familiar with either,



  #150  
Old March 21st 07, 01:11 PM posted to sci.space.policy,sci.space.shuttle,sci.space.history,sci.space.station
Craig Fink
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Posts: 1,858
Default Fluid Variable Intakes ( fun with expendable SSTOs ...)

Hi Derek,

I have a choice, how to respond to your post. The response can be negative
or positive. Which shall it be. Hummm, lets go with positive.

From my point of view: ;-) Interesting how in these threads, Henry invokes
religion as an argument for non-Atmospheric Flight to Orbit. The
connotation of "religion" negative and with a negative rate of change right
now. Then another, and another, till the choirs joins in. You should really
check before chiming in about God and another Man's religious belief. If
you must know, I'm Christian, of the variety that believes Physics is
simply Man's description of God's work. Math being the language that it's
spoken in. To understand Physics is to understand God's work, and therefore
it is the duty of Man to try the best he can to relieve himself of his own
ignorance.

Ignorance, also has a bad connotation, when it really shouldn't. For we are
all born ignorant, not knowing, and begin our own personal journey to
relieve ourselves of our own ignorance. No one can do this for us.

If there is something you don't understand (ignorance) about the concept of
Fluid Variable Intakes, just ask. Your more likely to get a response if you
ask nicely, positive than negative.

Jeff Findley, is just making comments about one example of an application of
Fluid Variable Intakes, not all applications. His comments are for the most
part true. In an application with compressors and turbines, a complicated
device that required a large effort to perfect, it's most likely true. Is
it more, or less. I don't know.

His comments about the lack of papers is most likely true, as Henry and John
have both made similar comments. But, not surprising, all new concepts
start out this way. Maybe Jeff, if he has the knowledge and background,
might write one of the dozens of AIAA papers to come. That is, if it truely
is a good concept/technique.

Looking at a much simpler application that would require much less work than
incorporating it with compressors and turbines would be a ramjet. A much
simpler engine, pure fluid manipulation, just adding a little bit more
fluid manipulation. Anywhere from trivial to massive, depending on the
approach and who's doing it.

Surely you've clicked and gone here by now
http://www.grc.nasa.gov/WWW/BGH/shorth.html
here,
http://exploration.grc.nasa.gov/educ...et/shortr.html
and here,
http://www.grc.nasa.gov/WWW/K-12/airplane/shortp.html
Looking for Ramjets, problems with, and when the region of usefulness ends
and why. Ah, here;
http://www.grc.nasa.gov/WWW/K-12/airplane/lowhyper.html
.... For aircraft speeds which are much greater than the speed of sound, the
aircraft is said to be hypersonic. Typical speeds for hypersonic aircraft
are greater than 3000 mph and Mach number M greater than five, M 5. We
are going to define a high hypersonic regime at M 10 to account for
re-entry aerodynamics. The chief characteristic of hypersonic aerodynamics
is that the temperature of the flow is so great that the chemistry of the
diatomic molecules of the air must be considered. At low hypersonic speeds,
the molecular bonds vibrate, which changes the magnitude of the forces
generated by the air on the aircraft. At high hypersonic speeds, the
molecules break apart ... Because of the pressure losses associated with
the terminal shock of the inlet, a ramjet has very limited performance
beyond Mach 5 ...

High temperatures, vibrating bonds of diatomic molecules breaking apart.
Ramjets are limited to Mach 5. So this is the point where the first ounce
of LOX needs to be added, to go past Mach 5 with a ramjet. Super-cold
liquid Oxygen, a huge heat sink, better use it wisely and add just enough
to keep the vibrating bonds from vibrating too much or breaking apart. Add
a little more Mdot (Mass flow rate) at Mach 6, even more Mdot at Mach 7,
quite a bit more at Mach 10, all to keep vibrating bonds of diatomic
molecules from vibrating too much and/or breaking apart. Extending the
useful range of a simple ramjet well past Mach 5 and probably past Mach 10.
Just how far? Sounds like a fun Trade Study.

Acceleration mission requirements are significantly different than
Range/Endurance mission requirements, which can lead to a significantly
different solution. Almost all in the atmospheric hypersonic flight studies
and research has been for Range/Endurance mission type profile. Even the
X-43A hypersonic research aircraft, they were very proud to have used only
fuel.

Adding the Oxidizer into the equations adds a whole new dimension that is
well suited for the Acceleration mission profile for many many reasons,
making Atmospheric Flight to Orbit not only possible, but with superior
performance over exo-Atmospheric Ascent.

The fun part to me, is the challenge of how to fit all the pieces of the
puzzle to do this.

--
Craig Fink
Courtesy E-Mail Welcome @
--

Derek Lyons wrote:

"Jeff Findley" wrote:

This isn't the sort of thing you can do with out *a lot* of detailed
aerodynamic, combustion, and thermal analysis. Not to mention how much
wind
tunnel time this sort of research would consume. This is the sort of
thing that can easily burn a billion dollars worth of research grants and
never
fly real hardware. Remember NASP?


Yes, I remember NASP. I worked on the NASP program and developed a closed
loop first stage guidance for the Space Shuttle. Really neat algorithm :-)
What a closed loop first stage guidance for the Space Shuttle and NASP have
in common, ????, your going to have to ask a manager about the convoluted
logic. I was young, and really just happy to have the opportunity to
develop it. The algorithm I named BIG, which used a small (2 pages of code)
3-dof trajectory simulation called SIMP, written by a coworker.

And NASP was easier than an
accelerator since it would have been optimized for supersonic cruise.


Not only that, but it takes the sole 'advantage' of an airbreather
(that one need not pack along the excess mass of oxidizer) - and
tosses it into the crapper.

So, where's the papers? Certainly someone who's done the work has
produced
a few dozen AIAA papers, right? I'm sure we'd all be interested in the
detailed analysis. Until then, liquid fueled rocket engines are the
preferred off the shelf solution to getting to orbit.


Such a stunning triumph of religious fervor needs not such mundane
things as actual proof.

D.



 




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