Microwave beamed power

In article . com,
wrote:

Joe Strout wrote:

And here I've been giving my kids helium balloons that last only a week
or two. Where can I get some of this lighter-than-air aerogel?

lighter-than-air aerogel? sounds like a good material to build aircraft
from but it could become a very difficult to clean up form of litter. I
wonder how pieces of it might affect jet engines or how it might feel
on a windy day to have to dodge chunks of the stuff.

I was being sarcastic. No such material exists.

Best,
- Joe

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Peter Fairbrother :

bob wrote:

zoltan wrote:
I have an experimental air breathing engine that generates about 1 MW
of power in terms of
the heat output of the propane burnt. This engine has a 7 inch nozzle
and an Isp of 4000.

Jet engines are not rated in ISP, but fuel consumed per hour per unit
thrust. They need air.

Isp is the same quantity as specific consumption, but inverted, except that
it's usually measured in seconds rather than 1/hours.

Eg one pound of fuel per pound of thrust per hour is the same as an Isp of
one hour or 3600 seconds.

And 4,000 s Isp is 0.9 pound of fuel per pound of thrust per hour specific
consumption.

The presence of air doesn't affect that (although it's absence might

Well the first problem is drag losses while the engine is breathing air. And
so far Zoltan has refused to do any tests of his design where drag will be a
factor.

Second problem, is what happens inside the engine when air speeds at the
intake reach Mach 1 and above. Zoltan again glosses over this.

The problem with Zoltan's claims is he seems to refuse to do any tests off a
workbench. For all I know the German V1 pulse engine rates an ISP over 1000,
but I know for sure that it can't operate near or above Mach 1.

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

A closed cell aerogel is nothing but an impermeable membrane! Lots and
lots of gas filled cells stuck together with each cell's membrane
impermeable to the gases. No mixing of gases within the stick, no
stratification of gases, no explosion risk while floating.

Detonation occurs when the cells are mechanically burst by the passing
of a vehicle which are mixed and heated by the shock effects.

The building you imagine would be along the ground track of the vehicle
under boost. It would not orient to the wind.

The building wouldn't be a building either. It would be four pipelines
in parallel. Two propellant pipelines, one aerogel precursor pipeline,
and one mixing line - that opened along its length. Propellant and
aerogel would be mixed in the mixing line - and the mixing line would
then be opened. The effects of local winds over the length of the
pipeline would largely cancel due to the immense drag of a miles long
stick of material you already mention.


The stick would take up the desired trajectory above the pipeline by
simply changing the density of the aerogel along the length of the
stick so that it came to rest at the appropriate density altitude. So,
denser parts of the stick would hover lower in the sky than less dense
parts of the stick. The angle of ascent would merely be a fuction of
the difference in density along the sticks length.

No helicpoters or other aircrat are needed to control it. Its immense
size means that it will be little affected by light winds and by
accurately controlling the density along its length - the altitude of
the stick along its length will be accurately controlled - creating a
precisely controlled trajectory for the vehicle powered by this
propelant stick.

Peter Fairbrother wrote:
Isp is the same quantity as specific consumption, but inverted, except
that it's usually measured in seconds rather than 1/hours.

The reaction mass in a jet engine is *not* the same as in a rocket. They are
apples and oranges. You don't buy jet engines rated in Isp. You don't buy
rocket engines rated in specific fuel consumption.

And lets face it. Jet engines don't work to well at 250,000 feet.

Don't just compare on units. Its really a different measure.

Greg

On 9 Aug 2005, William Mook wrote:

[snip]
The building wouldn't be a building either. It would be four pipelines
in parallel. Two propellant pipelines, one aerogel precursor pipeline,
and one mixing line - that opened along its length. Propellant and
aerogel would be mixed in the mixing line - and the mixing line would
then be opened. The effects of local winds over the length of the
pipeline would largely cancel due to the immense drag of a miles long
stick of material you already mention.
[snip]

Large Blimps and Zeppelins certainly care about winds...

But you are probably just writng those off as "too small" and "local"...

Ok, What about regional wind patterns. Say a low pressure center driving
a circulation pattern several hundred miles across...

What about coriolis? Since you are talking about making a thing that big,
coriolis forces *are* going to be a problem.

Since you are writing off "local" wind effects, then mesoscale effects
must matter... how about pressure differentials between weather systems of
several millibars... That will certainly mess up your nice smooth
bouyancy curve. And my experience with hot air ballooning suggests that
temperature will matter a *lot*...

The very concept of these free flying bouyant "propellant sticks" that are
supposed to be gobbled up by an ascending spacecraft is so full of obvious
problems as to resemble a large swiss cheese.

Gene P.
Slidell LA

--
Alcore Nilth - The Mad Alchemist of Gevbeck

The reason why we cannot use jet engines is because they are heavy.
They are more of a burden because of their weight than they are worth.
They also cannot be used over a wide speed range. At relatively modest
velocities the intake compressors become useless.

What I am working on is an engine that has the potential of overcoming
these problems. I do the intake compression by a ventury effect and my
engine can be very light because it is just an empty tube, similar to
an ejector ramjet. It gives thrust over a range of velocities from zero
to mach 6. Over mach 6 the same engine works as a decent hydrocarbon
rocket engine with both fuel and oxidizer injection. see
http://vtol.net/air.htm the diagram here shows approximate expected
induction jet performance.

As a useful thought experiment imagine what would happen if you simply
took a conventional rocket and surrounded it with a large tube. Shortly
after takeoff the rocket could turn off the oxidizer and fly on fuel
only, to the point where either the velocity is too high or the
altitude is too high and air breathing is no longer feasible.

In the induction jet the engine generates thrust on fuel only at sea
level at zero velocity.

The intake system is only a drag in a conventional ramjet. In the
induction jet the intake system contributes to the thrust.

Zoltan

"zoltan" :

The reason why we cannot use jet engines is because they are heavy.
They are more of a burden because of their weight than they are worth.
They also cannot be used over a wide speed range. At relatively modest
velocities the intake compressors become useless.

What I am working on is an engine that has the potential of overcoming
these problems. I do the intake compression by a ventury effect and my
engine can be very light because it is just an empty tube, similar to
an ejector ramjet. It gives thrust over a range of velocities from zero
to mach 6. Over mach 6 the same engine works as a decent hydrocarbon
rocket engine with both fuel and oxidizer injection. see
http://vtol.net/air.htm the diagram here shows approximate expected
induction jet performance.

As a useful thought experiment imagine what would happen if you simply
took a conventional rocket and surrounded it with a large tube. Shortly
after takeoff the rocket could turn off the oxidizer and fly on fuel
only, to the point where either the velocity is too high or the
altitude is too high and air breathing is no longer feasible.

In the induction jet the engine generates thrust on fuel only at sea
level at zero velocity.

The intake system is only a drag in a conventional ramjet. In the
induction jet the intake system contributes to the thrust.

What a lot of BS. You to date have not even run a test unit strapped to a
car at 100 KM/H much less tried to get to Mach 1. There is no such thing as
a dragless design and the fact that once you get pass the speed of sound in
your air flow it is impossible not to get shock/compression fronts. And what
about the body of your engine? 100% frictionaless material? There will be
drag - lots of drag.

Basicly, you are pushing a false claim because at no time do you have the
guts to trying running a model of your engine at any speed above ZERO (0)
KM/H.

When do we see some real tests being done?

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

zoltan wrote:

The reason why we cannot use jet engines is because they are heavy

And they need *air*, which you don't have for the last and most important
part of the flight profile.

Even a magical jet engine, that you claim to have *without* flight testing
is still not going to help much.

Put that engine on a RC plane and see how fast it goes.

Greg

I actually don't have to run my engine at high speeds. There is plenty
of data from Navajo and the Bomark ramjet engines. There is of course
friction and drag losses. That is the reason why I would switch to a
rocket mode of operation around mach 6.

The big deal is that I can run a ramjet at zero velocity without
oxidizer injection.

Zoltan

"zoltan" wrote:

...
The big deal is that I can run a ramjet at zero velocity without
oxidizer injection.

One can't help but note, however, that zero velocity is of limited
practical value.

/kenw
Ken Wallewein
K&M Systems Integration
Phone (403)274-7848
Fax (403)275-4535

www.kmsi.net