Re: Heavy Lift Design for Mining/Cargo Propulsion

On Apr 19, 7:30 pm, Willie.Moo...@xxxxxxxxx wrote:

: Rocket engineering is a little more sophistticated, even in
: mthe basics, than you put forth here;

: Check out these articles

: http://www.engineeringatboeing.com/articles/turbopump.htm

Yes, I can see the complexity there, which is why I'm not us-
ing "turbopumps" in the design. There's no "jet" being produced
for "thrust" here - just a magnetohydrodynamic injector for each
pellet blasted into the thrust dome.

No doubt that you've heard of thermoelectric electromagnetic
pumps that pump molten lithium liquid through a heat transport
system. That's the primary heat loop. A virtual slide show of the
heat loop system and control system can be downloaded here:

http://home.comcast.net/~samuel_ransom/pre.zip

INSTALLATION INSTRUCTIONS:

1) unzip pre.zip file in folder you create as "pre".
2) Go to DOS.
3) Go to /pre folder.
4) Type "PRESENTS".
5) Arrow down to "Display Presentation". Press <ENTER>.
6) Press the <F1> key and select with the arrow keys "T2.pre".
7) Press <ENTER>.
8) Press <ENTER> again and answer "Y" to loop presentation.
9) <ESC> to exit program.
10) After <ESC>, press X to exit back to DOS.

These are heat loops that center on the actual feed lines
that are able to magnetically blast the pellets at a rate of
120 per second into the thruster, where they become ignited
by the lasers (The fusion technology for applying laser ignition
uses 96 lasers per thruster (3 thrusters in all) that are
capable of focusing relativistic electrons with P-b gas into
magnetic confinement.

: http://space.au.af.mil/primer/rocket_theory.pdf

: These are chemical engines, there are similar articles for
: nuclear thermal rockets. Then, there are nuclear pulse rockets,
: where the mechanisms and numbers re way way different.

I believe it's the magnetohydrodynamic effect of the injection
mechanism that you're referring to, w.r.t. the pellet injector
design that uses a magnetic gun for the injectors (3 in all,
that are fed by feed lines, which are themselves charged
by coils. Grouping numbers of charging units into a single
fuel cell would require the length of the fuel cell to be a
multiple of the length of a single charging unit, that contains
a few hundred coils each - 360 to be exact.)

: Basically if you run an engine continuously, you've got to
: inject propellant against the chamber pressure, and that takes
: a certain rather large percentage (around 3% iirc) of the
: power of the jet. Which becomes MONUMENTALLY huge when
: you are talking about very hish performance high thrust engines.

I gave up the idea of arcjet propulsion when I noticed the
dependency on LOX and LH2 systems resplendent with design
problems such as impeller cavitation in the hydrodynamic
bearings, flow rate instabilities, and high temperature
inefficiencies - the SSME utilizes a design based on a 400
bar combustion chamber of the MBB engine CS50K-H, and
I don't believe that the sophistication of these systems is all
that warranted.

: Furthermore, most regeneratively cooled engines, recycle
: about 1% or more of the thermal energy to keep the throat
: from burning out. This doesn't work so well when you move
: beyond nuclear thermal or chemical engines. In fact the throat
: of a nuclear thermal rocket is cooler than a chemical rocket.
: The major improvement in performance comes from the use of
: liquid hydrogen - which is 1/9th the mass of hydrogen enriched
: steam the next highest performing genreally available rocket
: (when you burn hydrogen and oxygen in a 6:1 ratio)

Not much has been researched w.r.t. magnetic entrainment
in conjunction with coil-induced magnetohydrodynamics. This
is a whole different science - we're talking about coil injection
of the nuclear pellets into the combustion chamber, which is
itself open-space propulsion. Sure, there are electromagnetic
disturbances felt over 100 miles away - so by default this type
of propulsion doesn't require a launch zone within or near popu-
lated areas - a much needed safety and security precaution if
you're trying to stay incognito of surveilance by the compe-
tition anyway.

I'm envisioning an independent launch facility stationed com-
pletely outside the continental U.S., but close enough to be
reached by sea - such as an offshore platform - it's only a
matter of minutes before radio communication could be
restored to a rocket of this magnitude.


: When you talk nuclear gas core rockets with a continuous
: burning - fuhgetaboutit. You're just too hot, and too ener-
: getic to use these sorts of deals. That's what makes nuclear
: pulse so cool.

The feed lines of a magnetohydrodynamic injector can support
a ten minute charge or 600 second total specific impulse. This
would require a total of 111,672 inches of feed line packed
with pellets back-to-back. 75 lines @ 1,489 inches/line can
provide a maximum pellet repetition rate of 120 pellets/sec
for a ten minute specific impulse.

: First when you have really really fast pulses of energy in-
: teracting with things, you have very little spread of heat
: energy. The classic example is an ember from a burning fire
: falling on your carpet. You try to pick it up, and you get
: burned. You flick it back into the fire and you are safe.
: Why is that?

: Heat transfer is a diffusive process
: Momentum transfer is not

A device employing the utilization of charge entrainment in
an electrohydrodynamic device such as a magnetic injector
requires that the turbulent flow characteristics are calculated
for the fluid in question. A little research I've done yielded an
excellent mathematical model that described flow rate in terms
of both hydrodynamic viscosity, letter "v" (pronounced 'vue')
and (p - p_c), as the hydrodynamic pressure approached critical,
used an eigenvalue equation to solve for the dimensionless flow
rate at critical pressure.

Most of this stuff never got developed beyond theory - its just
waiting for an entrepreneur to come along and validate what's
never been done before - and that is putting it to practice.

: So, that's the answer to dealing with really really high
: energies - you hit something with energy fast enough, all
: the kinetic stuff takes place before heat gets a chance to
: diffuse away. That's why they can use ultra-fast laser
: pulses to machine C4 and not worry about an explsion

: I've calculated

: http://www.galasers.com/pdf/double_pulse_machining.pdf

So the two halves of a sphere of similar stuff are all that's
needed to "wick" the rest of the pulse unit. The core charges
could be mechanically assembled underground, under the close
inspection of the facility by IAEA inspectors to make their
independent judgements, and/or to install security cameras and
recording devices inside a facility for surveillance purposes.

: There is a cool drawing in my rocket text book back in the day,
: which is in my attic in a box, and I don't want to go find it to
: even check the title - anyway - it is a flow diagram showing
: the percentages of energy that are generated in a thrust
: chamber and how they flow around.

If the energy distribution on the surface of a pellet remains
constant for different size pellets, then 3.6 x 10^6 Joules re-
quires a pellet of radius 0.3265 cm. to achieve an equal energy
distribution of 2.685 x 10^6 J/cm^2. D3_He pellets require an
energy density of 1.847 x 10^9 J/cm^2. This is actually 261
times the energy currently provided by state-of-the-art 'silicon
wedge' lasers. We can increase the power to the pellet by in-
creasing the number of lasers, and increasing the power from
each laser, yielding a minimum power input of 2.25 X 10^13
Joules per second per dome, for three domes total. A 3.94 cm.
diameter pellet @ 250 hz meets the requirement for power input
to achieve subluminal velocity.

: Now, when heat is not being flicked away through ablation,
: or carried away through evaporation, into the vacuum, the only
: thing you've got to cool things down, is radiation. Stephan
: Boltzman is your friend in that case.

: P = 5.67e-8 J/m2/K/s * Area * Temp ^ 4

That's for a constant density profile.

I'm looking at a user guide for modeling a radiative blast
wave in Fortran that differs from the Sedov-Taylor blast wave
because the effects of radiation are included. The evolution
of the blast wave is followed by using an adaptive grid.
The grid parameters mass, density, and radiative energy in
logarithmic, the velocity (1000 km/sec), and other terms
(alpha, radius, and theta) are used to model a blast wave
that reaches a surface in 700 time steps.

: Now, I did a calculation this morning showring that if you
: had a 150 meter diameter plate, you'd have something like
: 35,342 sq m of radiative area (both sides of a circular disc)
: and you absorbed just 1/2 percent 0.5% of the jet energy
: INTO the plate (a really high number btw for nuclear pulse,
: really low number for steady state engines) - you'd have to
: be at the melting point of Boron to radiate away the energy
: produced by a 70,000 metric ton force thrust jet to acceler-
: ate a handy class space freighter (20,000 tons payload and
: 15,000 ton empty vehicle at two gees. So, your plate would
: be tungsten or carbon composite. Thrust to weight would be
: something like 14 to 1.(5,000 ton mass)

I stated earlier that I did a STUDY on ablation. This, I felt
needed to be established in order to prove the validity of
also using a high strength steel for the inside surface to
the ablation material.

The domes I'm using are (3) 100 foot diameter molybdenum -
so I guess for heat and strength purposes, ablation to the pro-
pulsion chamber surface is negligible, considering the fact
that each chamber is large enough in diameter, hemispherically
shaped, and the radiation distribution is handled quite
effectively through the use of the TZM alloy*, using an
ablative surface like carbonized metal or asbestos.

* Saleh, T. "Sputtering of Molybdenum" SNS Tech Note
FE-ME-011, August 1999

The only problem then becomes the heat transfer, which be-
comes readily handled and utilized effectively by the heat
loops - hull-internal steam powered electrical generation, etc.

: Having a large copper body doesn't change this. Look at the
: size of the sun, its the temperature it is at because the
: surface area and energy release are such that it rises to the
: temperature it needs to be for those two things to balance -
: there's also an effect of temperature on the SIZE of the sun
: - which is a whole otehr topic.

: Most nuclear pulse spacecraft coat the active area with mat-
: erial that gets ablated away by the rapid pulse. A flash
: bulb type blast is better than a long duration blast for this
: reason. Not only is ablated stuff potentially higher per-
: forming - more energy per unit mass - but less material car-
: ries away more heat than if you relied on evaporation rather
: than ablation processes. Check it out, flashing a ton of
: water into a ton of steam each second absorbs something
: like: 2.7 billion watts of energy, and flashing a ton of liquid
: ammonia into a ton of gaseous ammonia, absorbs 1.1 billion
: watts of energy. The Handy size ship at 70,000 tons of
: thrust, uses 14,000 kg/sec of propellant (of which 70 grams
: per second is the atomic charge, and the jet generates 17
: TRILLION watts of power and 0.5% of that is 82.5 billion
: watts - which radiated from a 150 meter diameter pusher
: plate heat it up to 2,900 K.

The primary heat loop calculation that I'm looking to engineer
involves the perimeter of the molybdenum dome, where 2297
Rankin converts to 1276 Kelvin, which is about 1700 degrees
colder than your pusher plate design - so according to your
figures, you're running a bit hotter. But I don't see how that
would be a problem, considering melting point of molybdenum
- 2615 centigrade, or 2888 Kelvin, which is just about 2900,
except that we're also coating the surface with a high temper-
ature ablative material with something carbonized, in order to
minimize the melt-out performance of the structure. How the
heat transfer would distribute through the blast surface
depends on the thickness of the metal itself - so IMO there's
nothing much left here, pending any problems with the method
of manufacture, assembly, facilities, etc.

: Like I said I worked it all out in detail, but mu computer
: froze up and I had more important stuff to do until now,
: I'm just recounting the numbers I got - I worked it out
: on a napkin at a coffee shop I had breakfast at, and threw
: the source materials away! lol.

Amazing how the some of the most "potential" issues of the
day get such passing notice, like a whim or afterthought of
something that happened nearly 60 years ago - that being the
magnificent Orion Project of yesteryear...

American
.

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