Re: Heavy Lift Design for Mining/Cargo Propulsion

On Apr 21, 8:59 am, "Martha Adams" <mh...@xxxxxxxxxxx> wrote:
"American" <samuelran...@xxxxxxxxxxx> wrote in message

news:33e9a8e6-fc25-4ad4-825d-f8ea965324a5@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
On Apr 20, 7:49 pm, Willie.Moo...@xxxxxxxxx wrote:





On Apr 20, 4:24 pm, American <samuelran...@xxxxxxxxxxx> wrote:

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

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.

[snip]

You are truly clueless. The magnetohydrodynamic injector is a pump
that injects the propellant, in this case the pellet you describe, and
the thrust dome as you call it is indeed the jet. If the jet is well
collimated your rocket is fairly efficient, if the jet is not well
collimated, it is less efficient.

| It's useless to argue semantics. Is there a magnetohydrodynamic
| injector that is patented as a pump? (Probably not, because
| I've already "invented" one!) The "jet" is more like controlled

<snip>

"You are truly clueless."  I don't see how that advances this
(to me) serious discussion.  It brings to mind the hot little
disputes that arise among small children, and it's off topic.

Mookie's numbers say we've got a problem here about practical
aspects of riding on a string of nuclear explosions.  This is
one of those things you use technology to find a solution.  The
easy solution, of course, is to space the explosions more far
apart in time until hardware buildable with (almost) existing
technology can cope with the nukes exploding nearby.

The interesting question to me here, is, what is the system that
fires those little nukes, what is its design, how much power does
it want, is there an existing proof of principle from which one
reasonably would commit some billions of dollars to build it?  ??

Titeotwawki -- mha  [sci.space.policy 2008 Apr 21]- Hide quoted text -

- Show quoted text -

I gave a lot of detailed information and it seems to have
disappeared.

But I will repeat briefly;

Its not semantics its physics. That you think its semantics shows
that you are STILL clueless despite my efforts.

Also, Martha, please understand that before you build the technology
you must first understand the physics. Otherwise you waste a lot of
time and effort learning the physics all over again.

As far as the comments about patents. The patent office assigns
rights to ideas so one may have a limited lifetime right to use a new
idea. This has little to do with physics - though the office won't
give you rights to things that don't comport with physical laws if
they can help it.

Please note that I'm making a point about the physics of a rocket
engine not what you call things (semantics) or what the patent office
says or how it classifies things.

Here is what happens in all rockets;

You have a reaction - be it chemical, nuclear, matter-anti-matter
annihilation -

it is sustained by energetic propellants - chemicals, nuclear
materials, antiprotons -which are fed into the reaction - this takes
energy and equipment to achieve.

those propellants react to produce reaction products - which exert
pressure in the reaction volume

those reaction products are collimated into a stream - which produce
thrust in a direction opposite the stream.

This is a rocket.- there are variations that are more complicated than
this, but lets get the basics first.

Lets look at some examples of your basic rocket...

Hydrogen and oxygen combust in a chamber that is then exhausted
through a nozzle to produce a jet of steam and hydrogen to produce
thrust.

Plutonium fission reactions in a magnetic chamber produce actinide
series products which are exhausted through a magnetic nozzle at high
speed.

Hydrogen fusion reactions in a more powerful magnetic chamber produces
helium which is exhausted through a more powerful magnetic nozzle at
higher speed.

Hydrogen and anti-hydrogen annihilates in a magnetic chamber and
produces gamma rays which are reflected by a powerful mirror to
produce thrust.


Type: Chemical reaction
Propellant: Hydrogen and Oxygen
Exhaust: Steam and hydrogen
Jet Speed: 4.5 km/sec

Type: Fission reaction
Propellant: Plutonium
Exhaust: Actinide Series Products, neutrons, working fluid
Jet Speed: 10,000 km/sec - 30,000 km/sec

Type: Fusion reaction
Propellant Hydrogen
Exhaust: Helium, hydrogen, working fluid
Jet Speed 30,000 km/sec - 90,000 km/sec

Type: Anti-matter annihilation
Propellant: Hydrogen anti-hydrogen
Exhaust: gamma rays
Jet Speed: 300,000 km/sec

Now in all cases, you've got to feed the reaction.

Pump hydrogen and oxygen against the chamber pressure into the
reaction chamber to maintain the reaction.

Insert plutonium against the pressure inside the magnetic chamber to
maintain the reaction.

Insert hydrogen against the pressure inside the magnetic chamber to
maintain the reaction.

Insert anti-matter against the pressure inside the annihilation
chamber to maintain the reaction.


Force times distance equals work. It takes energy to lift water up a
hill. Pump liquids against a head. Inject ions against a force.

Momentum is conserved - the momentum imparted to a rocket is equal and
opposite to the momentum imparted to ejected propellant;

MV = mv

So if you have a rocket, you also have a stream of ejecta collimated
in some direction.

Now moving objects contain kinetic energy. Operating a mechanism to
insert unreacted propellants in a reaction chamber under thrust, takes
energy.

the energy it takes to operate the insertion mechanism is a small but
constant fraction of the energy contained in the collimated ejecta.

Whether you call this process of feeding the reaction chamber a pump
or an injector doesn't matter. The physics doesn't change.

The amount of energy, hence the weight and cost, used by the 'pumps'
or 'injectors' or 'insertion mechansm' rises with the power of the
engine.

There are also heat transfer relations - which you asked about - but
until we get the basics right - I have no hope that you'll get those
any less hosed up than you get this.

Now, my only point is that by using a PULSE approach - allows you to
dispense with this relationship - with 'pumps' as well as with heat
transfer..

That is, you can build a tiny device that's self contained. Insert it
in a non-operating engine with minimal energy. Then detonate the
device to produce a pulse of thrust. Wait for the engine to clear,
and do it again.

The only trouble here is you're not as efficient as a continuous
system of thrust, but it solves a lot of problems of very high
performing engines.

We can build these high performing engines today. They only have a 10
to 1 thrust to weight, whereas a contnuously operating engine has a 70
to 1 thrust to weight - but their performance more than makes up for
this loss.

Just because we can build nuclear pulse engines today doesn't mean we
stop working on continuous thrust versions of the same thing.

.

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